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[ [ "understanding the basic concepts in memory organisation and applying those effectively in solving questions\n(well, actually proceeding to the question, I want to confess that this is a homework question, please do consider it and help me in improving my understanding a bit more.)\nI have recently started learning computer organisation and architecture. I have gained fair understanding for how caches are organised, how mapping between cache and main memory takes place (direct , fully and set-associative mapping), what is a page table(what are pages, blocks etc.), i can that say I have basic knowledge of segmentation , paging, virtual address and physical addresses.( at the basic level ofcourse).\nwell I have come across this question:\nA computer has 46-bit virtual address ,32- bit physical address, and a three level page table organisation. The page table base-register stores the base address of the first level table(t1), which occupies exactly one page.Each entry of t1 stores the base address of the page of second level table t2. Each entry of t2 stores the base address of the page of the third level table t3. Each entry of t3 stores a page table entry (PTE). The PTE is 32 bit in size.", "705" ], [ "The processor used in the computer has a 1MB 16-way set associative virtually indexed physically tagged cache. The cache block size is 64 Bytes.\nFirst of all I am facing difficulty in just imagining such type of a virtual computer. can any one help me by giving a simple steps on How to realize such a virtual computer on paper, or just how to understand what is given in the question. What is really asked?? How would one represent a computer having a 46-bit virtual address and having three level page table.\nwhat is virtually indexed and physically tagged cache.\nAfter reading what is given above , I feel that I just know the terms but I am unable to relate them together to solve problems. I will be glad If someone tries to explain how my thought process should be understand and apply these concepts practically to solve such types of problems.\nsome questions based on the above paragraph:\n1) What is the size of a page in KB in this computer?\n2) what is the minimum number of page colours needed to guarantee that no\ntwo synonyms map to different sets in the processor cache of this computer?\nA good resource where such problems are actually taught to solve will a appreciated. Good articles and views are most welcome.\nThankyou in advance !!", "705" ], [ "Can someone help me understand cache conscience radix sort? (excerpt from journal article attached)\nArticle:\nCC-Radix: a Cache Conscious Sorting Based on Radix sort\n============================================================================== (IEEE 2003)\nI'm trying to figure out what the author means by this section:\nExplanation of CC-Radix For clarity reasons, we explain the recursive version of CC-Radix sort as shown in Figure 3. However, we use the iterative implementation of CC-Radix for the evaluations in this paper because it is more efficient. The parameters of CC-Radix are bucket, which is the data set to be sorted, and b, which is the number of bits of the key that still have to be sorted. Constant b is explained below.\nCC-Radix(bucket, b)\nif fits in cache (bucket) then\nRadix sort(bucket, b )\nelse\nsub-buckets = Reverse sorting(bucket, )\nfor each sub-bucket in sub-buckets\nCC-Radix(sub-bucket, )\nendfor\nendif\nend\nFigure 3. Pseudocode of CC-Radix The algorithm starts by checking whether the data struc- tures to sort bucket fit in cache level Li. Those data struc- tures are vectors S and D and the counter vectors C, one for each of the digits of the key. If so, CC-Radix calls Radix sort. If the data structures do not fit in cache level , the algorithm partitions that bucket into sub-buckets by sorting the bucket by the most significant digit using the counting algorithm (explained above).", "603" ], [ "Here, we call this process of partitioning, Reverse Sorting, and it takes into account the computer architecture of the machine. For each sub-bucket, the CC-Radix sort is called again. Note that the first call to the routine processes the com- plete data set. Further calls to the routine process sub- buckets. Note also that certain subsets of the data may need more Reverse sorting calls than others depending on the data skew.\nNow, we explain the details of Reverse sorting and the sizing of the parameters of Radix sort. Reverse sorting. After each call of Reverse sorting, the number of digits that remain to be sorted for a specific sub- bucket is decremented by one.\nI don't understand the \"Reverse Sorting\" part of this - how is that supposed to work?\nI know this is a long shot, but I'm really stuck on what they mean. Any help is appreciated!", "705" ], [ "If I am correct about your query then there are some of the links which I mentioned below that may help you to understand the procedure. But to make better understanding approach should not be how it is working the approach should be how it could possibly work.\nLets check with the first approach.\nIf you read some open documents of MCH you will see the PCI works on separate clock and FSB works on separate clock. Think of all the components working in the system works on different clock rate, the word synchronized doesnt mean that \"If I say yes, at the same time you also say Yes\", indeed it means things happenning at the rising edge of the clock. Now all the components such as circuits deal with busses like PCI, circuits deal with interrupt system and control unit itself has different clocks. One approach is in order to intercommunicate between the components the approach should be based on the handshaking signals.", "7" ], [ "Lets suppose components X1 is the main component that deal with internal processing and component X2 is the component that deals with only ISA or I2C bus. Now data recieved by X2 should go to processing through X1, what handshaking signals required. The hypothetical approach is:-\n1 X2 notification that he has the data to X1 2 X1 acknowledge and ask to share the data 3 X2 start sending the data by keeping another signal ON to tell the X1 that data is on the bus (Just like in RAM we have the concept of RAS and CAS signals) 4 Once the data is completed by X2 it sends complete signal 5. And X1 acknowledge\nSecond approach I read on the MP book for x86, based on my understanding.\nThere is separate clock generated circuit in the computer that sends the clock to the processor and to the system, This circuit is tunned by a variable for example 2Y is the clock frequency on which the computer processor work and processor and clock generator is designed in such a way that 2Y gives to the processor and processor is made aware that it receives the multiple of Y clock frequency like \"2\" in this case and the board designer (An important person) should know that Y is enough frequency for the operation of every component mentioned on the board, thats why when he send the board for selling in the Market he mentioned the list of specifications for the compatibility.\nThird approach is my own idea where the system components have one controller and each controller has two clocks one that is running its part and the other for which it is communicating upstream with the single reference clock\nMoreover if we study pentium structure there is one pin which is known as cache miss and also if you study X86 you will see one pin known as Data ready, such kind of implementation is done that if an environment comes where sync-synchronized (The idea of perfect matching) not be the option (Board designer person decision) then create the wait states until the data is reliably received.\nBelow are some links that might help you. Also search clock domain crossing protocols\nhttps://en.wikipedia.org/wiki/Clock_synchronization http://paginas.fe.up.pt/~ee12248/Dissertation/wp-content/uploads/2015/03/PDI_ee12248.pdf", "552" ], [ "Please HELP me understand how the ISA works and how it is implemented with the microarchitecture\nHow is an ISA written? Is it just a bunch of binary combination encoding presets that is stored onto RAM? In other words, is it basically a “dictionary” of binary being defined as an instruction ‘word’ such as add? Once the instruction ‘word’ is recognized, does that mean an action is defined/assigned in that ‘word’? For example, let’s say 101010 is some encoding in x86 that = add, but then add = 111000, which is some electrical signal of add, then 111000 = action, then action = using ALU take register 1 and 2 and adds them? Also, is storing the result part of that action of add or is it it’s own separate thing? My guess is that it’s part of the action of add.\nFrom my understanding and using my analogy of a dictionary , I’ve thought about it in this way. Instead of thinking of it as one complicated dictionary with meanings on meanings on meanings, I’ve split it into two dictionaries: one dictionary for the encoding of your ISA (the opcodes/instruction format) and the other dictionary for what that encoding means, meaning it’s actions. There’s a microcontroller unit with a ROM aspect that is the dictionary for my so called “action”, which are the electrical signals that correlate to decoded instruction. Then there’s your ISA, set of instructions, that’s located on your RAM which is a dictionary for the instructions when the opcode being called. Am I correct? Please tell me I am.", "705" ], [ "Follow up, how is the ISA loaded into RAM to begin with? What tells it to do that? Is it the microcontroller unit? Also, how does an ISA even go about naming and defining certain registers to have a certain roles and functionalities? I’m genuinely confused. Is the ISA like an OS where as soon as the computer boots, the instructions get stored into RAM (if so, how?) and these registers immediately recognize their names and roles? I definitely feel like I have some sort of misconceptions and misunderstandings here.\nThen there's also the instruction cycle which I learned about separately. It's fetch, decode, execute. What is making it do that? How is the cycle being executed? Is that programmed through the ISA? Is it some kind of hardwired thing at the microarchitecture level? If so, please explain.\nLastly, how exactly does the implementation process of the ISA and microarchitecture work? Do you create the ISA first then implement that onto the microarchitecture level? Or is it created by working hand and hand with each other? By that I mean, does Intel have two teams: one dedicated on creating the ISA and one on creating the design of the microarchitecture(hardware)? If the answer is two separate teams, I do not understand how you can go about creating your digital logic(hardware) efficiently without working close together with the ISA team. Even after creating and finishing their product, how do they implement it with one another? Please help me understand the implementation process :(", "705" ], [ "This all deals with one of the major, and complex tasks in any processor. Namely decoding instructions. On a simple conceptual level, this may be viewed as taking the contents of the instruction register and translating this into logic commands to the various functional units of the processor to perform the desired action and then fetch the next instruction into the instruction register and repeat.\nTraditionally there are two competing camps called Random Logic and Microcode.\nThe random logic camp tends to look at the task as a sort of huge logic problem. Given an input (the instruction set), what outputs are needed (the instruction implementation). The result tends to look like a huge array of gates, flip-flops etc arranged in a non-intuitive (looking random, but no actual randomness here). Needless to say, for any non-trivial processor, this can be really complex.\nThe microcode camp on the other hand, maps each instruction to a stored program for a very simple but fast processor. Often, the microcode program is stored in very wide memory so that many program units can be simply connected to fields in the microcode with little or no additional decoding. In a sense, the microcode is implementing the random logic's output by table lookup.\nThese views are a gross simplification. Almost all random logic designs have small memory elements in them to simplify the state machines that are part of all processors, like the instruction fetch, operand decoding, or responding to interrupts.", "125" ], [ "Likewise, almost all microcode machines employ some logic to speed up the decoding of the microcode to avoid needing insanely wide microcode memory. In addition, logic is often employed to allow the microcode to loop or branch to create more complex behaviour.\nWhile microcode is extremely difficult to write, when an error is found, the code \"simply\" needs to be updated (assuming that you don't run out of microcode space, then well, problems) When a bug is found in the random logic decoder, it is not uncommon for the whole logic formulation to be affected. This can make random logic designs very hard to get right. The Z-8000 used random logic and its design was plagued by bugs in the instruction decoder. On the other hand, the simpler MC6809 also used random logic decoding and was highly successful.\nThe advantage of random logic is that it avoids the overhead of fetching the microcode from it's storage. In simpler processors avoiding this overhead can result in savings of silicon (that is money) and clock cycles (that is time).\nRISC computers have much simpler instruction sets than CISC machines. This is a major reason why the random logic decoder is so often associated with RISC chips. CISC chips have intricate, complex instruction sets, so microcode is highly favoured for those designs.\nI understand that most modern processors use a hybrid approach. Random logic for the simple and/or highly time critical stuff and microcode for the more complex behaviour and/or exception handling.", "125" ], [ "How fast is this Division Algorithm\nI wrote an algorithm for integer division. I'm wondering how fast it is asymptotically. I used RAM model myself to asymptotically analyse it, but I found out that:\nElementary CPU instructions like shifting and adding, are not constant as the integers grow arbitrarily large.\nSo it seems my analysis is wrong. I'd like to know how fast the algorithm is. I'll leave in my original analysis using RAM model of computation.\nI think I've found a linear time algorithm to solve this problem. I will attempt to calculate it's time complexity. I hope someone in the community, can point me to where I may have made a mistake. I am assuming the RAM model of computation. In particular, I am making these assumptions.\n(1) Addition and subtraction take one primitive operation.\n(2) Boolean shifting takes one primitive operation.\n(3) Reading from memory takes one primitive operation.\n(4) Writing to memory, takes another primitive operation.\n(5) Logical comparison takes one primitive operation.\n(6) Returning a value takes one primitive operation.\n(7) Creating a variable or an array takes one primitive operation.(Irrespective of size of Array)\n(8) Assignment takes one primitive operation.\nPlease correct me if I made any wrong assumptions. I will try to determine the run time complexity of this algorithm. I will use $+i$ to denote a particular piece of code takes $i$ primitive operations and $+k \\cdot i$ to denote $ki$ primitive operations.", "143" ], [ "I will attempt to total all the primitive operations. (I will keep a tally at each 'block' of code of total expenditure of that block in the form $T = k$ where $k$ is the total so far)\nThe section below outlines the algorithm for those who may want to fix, improve, understand, etc.\nThe Idea of this algorithm, is that $\\log_2(2^n) = n$ (Initial growth of the quotient using powers of two.) It attempts to reduce time-complexity of the algorithm, at the expense of space complexity.\nMultiplication as far as this algorithm is concerned, will be replaced by use of the binary \"<<\" operator.\nWe Know that the rest of the quotient is between $0$ and the previous value of $k$(Because b was lower than k*a). So we run a binary search between 0*a and previous k*a. An array of all powers of two up to the current value of k(That produced k*a > b) are kept. This array is then used to perform a binary search.\n$\\log_2(2^n-1) = n-1$\n$n + n-1 = 2n$ $$f(n) = \\Theta(n)$$\ncompare(x, y) A comparison function, that shall be used to aid binary search.\n{\nif(x == y) return 0$+1$\nelse if(x > y) return -1$+1$\nelse if(y > x) return 1$+1$\n}$+1$(for return)\n$T = 4$(Whenever this function is called, 4 primitive operations take place.)\na = divisor, b = dividend, q = quotient, r = remainder $+4$ (Creating 4 variables) m = Array size. Set it to whatever you want. Ideally it should be $\\ge$ maximum size of input $n$\n$state = 1 If the numbers have the same sign 0 otherwise. $+3$(Creating a variable, Logical comparison and assignment)\ndivide(a, b, &q, &r) q and r are passed to the function by reference. So that both may be returned.\n{\nconvert a and b to unsigned integer types. $+2$ q = 0$+1$\nk = 1 This will be the multiplier by which bwill be tested.$+1$\nm = 100 (m should be $\\ge \\log_2(b)$ or n. I'm just arbitrarily picking $100$ Array[m] Initialise all elements with 0 (If it increases time complexity of algorithm, initialise only the first element to 0. $+1$ (Or $+m$ it doesn't matter this is a constant and has no bearing on the asymptotic complexity.)\nArray[0] = {0} $+1$\ni A variable to be used as a control variable for the array.$+1$\nfor(i = 0 ; b >= (a << i) ; i++) $+3$(One logical comparison, One increment of $i$ each time loop is executed.", "743" ], [ "General question about how CPUs send and receive data/bytes to hardware?\nRealize I didn't mention x86 or any more details to make this non-specific to any platform, but to just get a general idea of how this is done(this is also a long question with a lot of details).\nI know most PC motherboards for desktop (if not all) computers have two sections; north and south bridge, and a chipset connects them together between the CPU's implementation and the buses carrying data around the board.\nThe x86 CPU has a register, I think, called the accumulator, which has eight bit AL, sixteen bit AX, and thirty-two bit EAX. Data for these registers are typically used for arithmetic operations, general purpose machine instruction, etc.\nAlso, supposedly for I/O access, such as with Port I/O. There is Port I/O and MMIO (memory-mapped input/output), which are two methods of accessing data outside the CPU.\nI have inspected memory maps, but I'm still unclear on whether or not it's part of an instruction fetched from memory (i.e., MOV AL, 0FF) or from some other instruction to actually access hardware.\nMy basic question is, what specific instructions are used to write and read data from hardware, from a bare machine perspective; no device drivers, no operating system, and no firmware interrupts. This is the very essence of how system software must be made, and there's little complete coverage on how this works from the CPU's register to the hardware itself.", "798" ], [ "I have seen BIOS interrupts, but that abstracts away details. Also, the developer had no idea what happens beyond INT 13.\nSo, despite my broad question, is there some specific way this is accomplished, either by instruction, correct value set in a register, etc.?\nExample: Say I want to make a few beep noises. The sound hardware is responsible for making any noise at all, so I would, from a bare machine perspective, once again, have to directly access the hardware and its components, circuitry, or otherwise internal hardware registers or such to make noise. Is there a complimentary way of doing this that is specifically outlined or guidelined per-platform, or does it vary based on every specific piece of hardware and CPU?\nIf so, what would help me unravel that mystery to program for it this way? Would the card be, let's say, mapped a special address you write to? Then I would just set a register and the CPU will just send it there with whatever value it contains?\nI am confused, and nothing makes clarity of this, because abstractions exist even at the low-level that create a barrier of the unknown.", "705" ], [ "While all current CPU's appear to use an iterative approach as aterrel suggests, there has been some work done on non-iterative approaches. Variable Precision Floating Point Division and Square Root talks about a non-iterative implementation of floating point division and square root in an FPGA, using lookup tables and taylor series expansion.\nI suspect that the same techniques may make it possible to get these operations down to a single cycle (throughput, if not latency), but you are likely to need huge lookup tables, and thus infeasibly large areas of silicon real-estate to do it.\nWhy would it not be feasible?\nIn designing CPU's there are many trade-offs to make. Functionality, complexity (number of transistors), speed and power consumption are all interrelated and the decisions made during design can make a huge impact on performance.\nA modern processor probably could have a main floating point unit which dedicates enough transistors on the silicon to perform a floating point division in a single cycle, but it would be unlikely to be an efficient use of those transistors.\nThe floating point multiply made this transition from iterative to non-iterative a decade ago. These days, single cycle multiply and even multiply-accumulate are commonplace, even in mobile processors.\nBefore it became an efficient use of transistor budget, multiply, like division, was often performed by an iterative method.", "129" ], [ "Back then, dedicated DSP processors might dedicate most of their silicon to a single fast multiply accumulate (MAC) unit. A Core2duo CPU has a floating point multiply latency of 3 (the value comes out of the pipeline 3 cycle after it went in), but can have 3 multiplies in flight at once, resulting in a single-cycle throughput, meanwhile it's SSE2 unit can pump out multiple FP multiplies in a single cycle.\nInstead of dedicating huge areas of silicon to a single-cycle divide unit, modern CPU's have multiple units, each of which can perform operations in parallel, but are optimised for their own specific situations. In fact, once you take into account SIMD instructions such as SSE or the CPU integrated graphics of the Sandy Bridge or later CPU's, there may be many such floating-point divide units on your CPU.\nIf generic floating point division were more important to modern CPU's then it might make sense to dedicate enough silicon area to make it single cycle, however most chip makers have obviously decided that they can make better use of that silicon by using those gates for other things. Thus one operation is slower, but overall (for typical usage scenarios) the CPU is faster and/or consumes less power.", "129" ] ]

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[ [ "The Legendary Blue Crystal Microphone\nIntroduction: The Legendary Blue Crystal Microphone\nAfter reading a great comment to one of the most popular video of my channel, I got driven in one of the most positive way to push the limit of my knowledge and tackle my first ''Chemical'' project.\nTo make a short story out of a big story:\n1. I made a video on how to create a Piezo disk microphone years ago.\n2. It was basically just me showing how to solder 2 wires to a piezo disk element\n3. 2 years later, someone made a comment, you can read it here:\nSo, you're another person NOT making a piezo mic, but repurposing an existing one. The closest I have found is the Colin's Lab where he grows piezo crystals. I can't find any videos of people actually making a piezo mic.\n4. Instead of bursting in tears or getting angry, I decided to accept the challenge\n5. I did my research and 2 weeks later, I had harvested my own Rochelle Salt Crystal...\n6. Another week later, I manage to 'manufacture' these crystal and create my own microphone with it.\nToday, I present you the recipe of my hard work and also, the Legendary Blue Crystal Microphone.\nSupplies\nTo harvest the Rochelle Salt Crystal you will need the following.", "51" ], [ "Fortunately, everything can be found at the grocery store, if you live in the same city I live, it is possible that the cream of tartar is out of stock, sorry! ;)\n* 250ml of Distilled Water\n* 150g of Cream of Tartar (Potassium bitartrate)\n* 500ml of Baking Soda (Sodium Bicarbonate)\nTo manufacture or house the Crystal and create a 'usable' microphone, you will need the following or so:\n* Patience\n* Dexterity\n* A small clamp\n* Epoxy or transparent silicon\n* Wires to connect to the mic\nStep 1: Create the Sodium Carbonate\nWait, I thought you said Sodium Bicarbonate which is baking soda!\nYou will need to create Sodium Carbonate out of the Baking Soda which is Sodium Bicarbonate. Fortunately for us, the process is fairly simple, you only need to pour the Baking soda in a pot on the oven and put the heat to high.\nStir the powder until you see some bubbles, this is the CO2 and the water evaporating.\nWhen there are no more bubbles, reduce heat and put aside.\n***BE REALLY CAREFUL SINCE THE POWDER WILL GETS HOT***\nIf you don't feel comfortable with this process, watch that video since it was also my first time doing so and was fairly easy:\nStep 2: Hot Bath\nPour 250ml of Distilled Water inside a Pyrex measuring cup and add 150g of Cream of Tartar. Prepare a hot bath with a pot and regular water (1/3 of the pot should do) and make sure the measurement cup will fit in there.\nStir the distilled water with the cream of tartar to ensure that it’s well mixed and put the measurement cup inside the hot bath. (Make sure it is not boiling but just near boiling)The goal here is to heat the solution as much as possible.\nStep 3: Chemical Reaction\nTake half of a tea spoon of your Sodium Carbonate and mix it with the solution which is getting hot. You will see a lot of bubbles forming, this is the chemical reaction and I hope your measuring cup is big enough, at least twice the size of your solution. (500ml is fine)\nProgressively and slowly add the Sodium Carbonate to the mixture and wait between each reaction. Stir Often! When the solution gets from a milky tone to a clear yellowish tone, this mean that the solution is ready.\nStep 4: Filtering\nAdd a last half tea spoon of Sodium Carbonate to make sure there is no more reaction in the solution. Crank the heat of the hot bath and make sure the solution comes to a point of ‘near’ boiling. Once it’s there, carefully remove from the hot bath (use oven glove or special tool) and make sure the solution doesn’t cool down as you will have to pour it inside a Coffee Filter and collect the liquid into another container.\nThe liquid is hot as well as the container so be really careful when manipulating it!\nNote that this step is crucial. If the solution cools down before you filter it, most of the crystal will get stuck inside the coffee filter and your solution will be sterile, which means, No Crystal.\nStep 5: Collecting the Liquid\nTransfer this liquid into your desired container and put to the fridge.", "440" ], [ "Neko Punk Synth V2\nIntroduction: Neko Punk Synth V2\nHey guys and welcome back, this is my Neko Punk Synth Version 2 which is a cat-themed Synth powered by an Arduino Nano and Mozzi Library.\nBy Changing the position of 5 sliding pots, Mozzi can produce much more complex and interesting growls, sweeps, and chorusing sounds. These sounds can be quickly and easily constructed from familiar synthesis units like oscillators, delays, and filters.\nYou can check out Mozzi Library from here- https://www.instructables.com/Arduino-Based-Synth-...\nSupplies\nThese were the things used in this built-\n* Arduino Nano\n* PAM8403 Audio AMP\n* Custom PCB which was provided by PCBWAY\n* Li-ion 5V Boost Module\n* 3.7V Li-ion Cell\n* 3D Printed Enclosure\n* 4Ohm Speaker\n* Slider Pots\nStep 1: Previous Edition - Stepped Tone Generator AKA Atari Punk Console\nThe Previous edition that I made a few weeks ago was based on the original Atari Punk Console was first made by <PERSON> in 1980.", "485" ], [ "It utilizes an astable multivibrator setup which triggers a monostable setup. by combining these two setups, we get a Stepped Tone Generator or an atari punk synth.\nThis was easy to make but I was not pleased with its result.\nA year ago, I've made a similar synth with Mozzi Library which worked quite nicely so I thought why not use Mozzi in the V2 of Neko Punk Synth, to make things super cool, I used sliding pots which gives this synth its cyberpunk-ish looks.\nStep 2: Circuit Designing\nV2 PCB was probably the simplest Circuit board that I have ever made.\nIt uses an Arduino Nano as a base Microcontroller, five slider pots are connected with Arduino nano.\nD9 goes into the input of the PAM8403 Audio AMP Module and the output of PAM8403 is connected with two CON2 Pins so we can add Speaker with it.\nI prepared the PCB in my OrCad PCB Suite and added a few graphics to increase the aesthetic of the Board.\nStep 3: Boost Module\nThis whole setup requires 5V to work.\nTo Power this setup, I have to use this Li-ion Cell Boost module that you can find online, these modules are very inexpensive and work pretty well.\nIt Boosts 3.7V of Li-ion Cell to constant 5V 1A or 2A for our MCU setup to work.\nStep 4: Getting the Board From PCBWAY\nI used PCBWAY PCB Service for this project. I uploaded the Gerber file of this project on PCBWAY's quote page.\nFor this Synth Board, I choose white solder mask color as I have added Quite a few round graphics and custom art on the TOP side of the Board.\nBlack silkscreen looks awesome with white soldermask color.\nI received the PCBs in a week and the PCB quality was pretty great, This PCB is Huge and I like how the quality of these PCBs was not compromised because of size.\nCheckout PCBWAY from here- https://www.pcbway.com/\nStep 5: PCB ASSEMBLY\nNow this Board doesn't have any SMD Componenets so we only had to place everything on this board manually and solder them with a soldering iron.\n* I first gather all the materials and started the assembly process with Slide Potentiometers.\n* I then put all the Pots in their place from the top side and solder their pads from the bottom side of the PCB.\n* After this, I added Arduino Nano and PAM8403 modules in their place, and the assembly was pretty much completed.\nStep 6: Uploading Code\nthe main sketch of this project is based on Mozzi Library.\n/*\nExample using 2 light dependent resistors (LDRs) to change\nFM synthesis parameters, and a knob for fundamental frequency,\nusing Mozzi sonification library.\nDemonstrates analog input, audio and control oscillators, phase modulation\nand smoothing a control signal at audio rate to avoid clicks.\nAlso demonstrates AutoMap, which maps unpredictable inputs to a set range.\nThis example goes with a tutorial on the Mozzi site:\nhttp://sensorium.github.io/Mozzi/learn/Mozzi_Intr...\nThe circuit:\nAudio output on digital pin 9 (on a Uno or similar), or\ncheck the README or http://sensorium.github.io/Mozzi/learn/Mozzi_Intr...\nPotentiometer connected to analog pin 0.\nCenter pin of the potentiometer goes to the analog pin.", "472" ], [ "DIY Studio Light/ Light Box\nIntroduction: DIY Studio Light/ Light Box\nHey Everyone what's up.\nThis is my DIY Studio Light Project\nWhich basically is a do-it-yourself studio light that is made from a custom 3D Printed body and a custom PCB which were both provided by PCBWay.\nQuestion\nIs it better to Buy an expensive Studio Light or Make your own DIY Studio Light with custom 3D Printed parts and PCB?\nWell, the goal for making this project was just that, I wanted to make a DIY Studio Light for my current \"Maker Setup\" as the lighting in my lab bench is not very great.\nCommercially available light costs above 50$ (good ones) but why spend money on them when you can make your own Studio Light, Body can be made from a 3D Printer and the circuit can be manufactured by a PCB manufacturer.\nIn this Instructables, I'm gonna show you guys how I made this DIY Studio Light in few easy steps.\nLet's Get started!\nSupplies\nThese are the things that I used for this built\n* LEDs (NICHIA JK3030 3V .2W LED)\n* 1.5 Ohms Resistance 1206 Package\n* 0.47 Ohms Resistance 1206 Package\n* 100uf Capacitor\n* 63uH Indictor\n* SS34 Diode SMA\n* DC Barrel Jack\n* Custom PCB (which was provided by PCBWAY)\n* Custom 3D Printed body (which was also provided by PCBWAY)\n* SIC9301A led driver IC x2\n* 12V DC FAN (Generic small one)\n* 12V SMPS Power Supply\nStep 1: Basic Structure\nMy goal was to make a DIY Studio Light completely from scratch to compete with existing light available in the market.\nThe reason for starting this project was the cost of the existing setup, Commercial Studio Light isn't exactly cheap and I need at least 2-3 Lights which would cost a lot so I made an easy-to-make Studio Light with custom PCB and 3D Printed Body.\nAlso, I'm using a generic FR4 PCB here. these LEDs produce a lot of heat so why I'm not using MCPCB (metalcore) instead of FR4 (fiberglass) for making a better-LED PCB that can disperse heat better than FR4 Board?\nYou see, I have added lots and lots of Via in this PCB, these Via will conduct heat from the top side and transfer that heat to the bottom portion which will result in Heat getting Disperse equally. Then at the backside, there's a 12V Mini DC FAN which cools down the PCB heat.\nApparently, Metal PCBs or MCPCBs are not $$$ wallet-friendly and if I have used a metal PCB in this project, I also have to use another FR4 board for LED Driver IC setup.", "982" ], [ "So I saved a lot by making a single PCB that contains the LEDs and Driver IC setup.\nAlso, the Body of this light is made from PET-G which is quite a durable plastic so overall, this DIY Studio Light can sustain heat.\nStep 2: Schematic\nThe main schematic of this project is attached above and as you can see, it's not very complex. it contains two LED Driver IC setups both with their LOAD (LEDs) connected separately.\nTheir Input side is connected with each other which is the common Input VCC and GND. we will supply 12V to these two terminals to run this board.\n(yes, I haven't used any Microcontroller or any Switching IC in this Circuit)\nStep 3: PCB Designing\nWith the above Schematic, I prepared the PCB in my CAD software.\nThe board outlines were already designed in the Fusion360, I used its measurements as a reference to make the PCB.\nI placed LEDs at the center of the board and maintained an equal distance between them, to keep things symmetrically accurate.\nAnd as you can see, I've placed lots of Vias in this PCB. Vias cover almost 70% of this PCB and they are here for Conducting heat as well as connecting one side with another side of the board.\nAnyways, after finishing the PCB, I exported its Gerber data and send it to PCBWay for samples.\nI Received the PCB in 7 days which is pretty fast, and it also came with a PCB Scale which was pretty cool (I have used my beans to get that scale though)\nI have to say, PCBs that I've received were great as expected, PCBWay, you guys rocks.\nCheck out PCBWay for getting great PCB Service for less cost!\nNext is the PCB Assembly Process.", "472" ], [ "Atari Punk Synth, Neko Edition\nIntroduction: Atari Punk Synth, Neko Edition\nHey Guys how you doing!\nThis is the NEKO PUNK Synth which is a cat-themed Atari Punk Console based around two-timer ICs.\nThis circuit utilizes an astable multivibrator setup which triggers a monostable setup.\nBy combining these two setups, we get a Stepped Tone Generator or an atari punk synth.\nAPC or the Atari Punk Console was first made by <PERSON> in 1980 and it was called sound synth back then. Also, it is not made by Atari at all, the only reason for calling this sound synth APC is the resemblance of sound produced by synth is somewhat similar to the early atari games, beeps hums, and other stuff.\nAnyways, this version of mine follows the same old two-timer ic circuit, only twist here is the cat-themed box and the addition of a sound AMP between speaker and APC.\nSupplies\nthese are the materials used in this project-\n* 555 Timer IC (both THT and SMD)\n* 10uf capacitor\n* 0.1uf capacitors (SMD and THT Both)\n* 1K Resistor\n* FR4 PCB Copper Clad Board\n* 10K POT\n* 500K POT\n* PAM8406 Module\n* Breadboard\n* Power Source (in my case, a Lipo Cell with a Boost module 5V)\n* 4 Ohms Speaker\n* 3D Printed Parts\nStep 1: PROLOGUE\nSo the idea here was to make an APC, a completely DIY APC which will have an inbuilt power source and it should be portable so anyone can carry it from one plate to another.\nPreviously, I've made a similar APC with an Atmega328PU microcontroller connected with a PAM8406 Module.", "485" ], [ "It uses Mozzie Library to modulate sound with 5 potentiometers.\nhttps://www.instructables.com/Arduino-Based-Synth-...\nThat setup worked flawlessly without any issue, but the problem was its cost. I wanted to make a similar synth without using any Microcontroller in this project to overcomplicate things, so instead of relying on a library, I used the good old-timer IC Tone generator setup which utilizes two 555 timer ic connected in an astable multivibrator and monostable setup.\nthis significantly reduces the cost of the overall project and anyone can remake this without utilizing any code.\nStep 2: Getting Materials From ALLCHIPS\nAs for the Source from where I get most of these components, I got the Timer ICs, Resistors, and capacitors from ALLCHIPS.\nALLCHIPS is a well-known Platform For Electronic Components Supply, they have everything that you need for any type of project.\nThey are an all-in-one procurement department of hardware manufacturers as all components I used in this project were provided by ALLCHIPS which was a cool and helpful thing!\nAlso, they have this BOM IN ONE BOX thing which is such a helpful thing, we provide them a BOM List and they procure all the components and deliver them \"IN ONE BOX\" which is an efficient way of purchasing components for any project!\nCheck out ALLCHIPS for more info.\nStep 3: GETTING STARTED\nFor getting started, I first prepared a breadboard version to check if the circuit is working properly or not.\nafter making sure that the schematic was working, I prepared a PCB Version.\nStep 4: Breadboard Edition\nTo prepare the breadboard edition first, I used the Tone generator Circuit (which is attached above) that consists of two separate Timer ICs connected in both an astable multivibrator and monostable multivibrator. their output goes into a PAM8406 Module and the whole setup is powered by a lithium battery boost module.\nSound can be modulated via Pots connected with Timer IC 1,2 and between the Timer IC output and speaker input.\nStep 5: PCB Edition\nFor the PCB Edition, I first prepared the schematic of the board by following the same breadboard layout but the only difference here would be that I have used SMD Version of 555 timer ic which is in the SOIC8 Package.\nAlso, for this version, I will be using a completely DIY PCB instead of a proper one because this project is still in its early phase and I will add a bunch of stuff in it later on so for now, this design has three pots.\nStep 6: STEPS\n* After finalizing the schematic and making the PCB, I printed its bottom layer on a glossy sheet in the real size.", "485" ], [ "Make Your Own Arduino AC Dimmer | Drive Motors & Lights\nIntroduction: Make Your Own Arduino AC Dimmer | Drive Motors & Lights\nHi every one, here <PERSON>, and I want to show you how I made my own Arduino AC dimmer that can control AC loads such as motors and lights easily. It has the power to handle 1200+ Watts and It's a very nice project for domotics and home automation because the microcontroller I used is the ESP8266 that has WiFi capabilities and the code could be adapted with few changes.\nHere I leave you a tutorial with all the information so you can make your own version.If you are a visual learner I know that a video worth more than 1000 words, so here is a Tutorial video. (I am a Spanish speaker, so please consider turning on English subtitles):\nStep 1: Skills Required:\nThis project may seem difficult or very complex, but it is definitely not completely, since you will have all the guidance for the construction, it was difficult for me to design it to make life a little easier for you.", "382" ], [ "Any conceptual doubt, you are free to ask it without problems.\n* You should have an understanding of:\n* 3D Printing (Optional for the case).\n* Arduino programming (I give you the code).\n* Soldering through hole components.\nWarning: In this project we will handle main power, so please be careful\nStep 2: Components and Parts List\nThe Electronics discrete components as resistors and transistors will be attached in a BOM file in the PCB Step.\n* Here is the list of what you will need for the whole process:\n* -10kohm Potentiometer.\n* -2 Double Terminal blocks.\n* -AC motor of your preference (single phase).\n* -Dimmable Lightbulb.\n* -Small 5 volts cellphone power supply.\n* -Measuring tools: multimeters, clamp meters (optional).\n* -Micro USB SMD connector.\n* -1.3 inch OLED Display.\n* Wire.\nBOM list of PCB components attached.\nGreat, cheap and awesome Graphical Multimeter to watch the Sinusoidal AC wave form\nStep 3: Circuit Diagram\nHere is the Circuit Diagram of our project:\nIt has all the internal conections of the circuit that will us allow to create the PCB design later.\nI also attached the PDF of the Schematics so you can see it better.\nStep 4: PCB Design and Ordering\nFor the implementation of a good project we need a reliable assembly for the circuit that makes it up, and there is no better way to do it than with a good PCB.\nHere you can download the Gerber, BOM and Pick & Place Files, the ones you need to order your PCB on your PCB manufacturing company.\nI suggest JLCPCB:\n$2 for 1-4 Layer PCBs⚡, Get SMT Coupons🎫\nUnZip the .rar file with a software like WinRar or any other.\nStep 5: 3D Parts (Housing + Motor Holder)\nHere you have the STL files for the 3D parts of the project.\n* Housing.\n* Cover\n* Potentiometer Knob and nut.\n* Button cap.\n* Motor holder.\nStep 6: Programming the ESP8266 Microcontroller\n1- To program the ESP-12s we need to connect it directly to our PC through the USB cable, open the Code \"ACControl\", install the libraries that I also attached and click on upload.\nIf the current measurements are wrong on your display, or you want to improve them, you can tune experimentally this parameters in the code:\n* float Sensibilidad = 0.066; //sensitivity of the 30Amps sensor (see datasheet of ACS712 if use 20A or 5A version).\n* float intercept = 35952.685; // Change this until you got closer as posible to the real current.\n* float slope = 273; // Change this until you got closer as posible to the real current.\n* float testFrequency = 60; // frequency of your circuit (Hz)\n* float windowLength = 40.0 / testFrequency; // num of cycles that will be test.\nCODE, LIBS, EVERYTHING, DOWNLOAD FOR FREE HERE\nStep 7: Wiring Up\nFollow this few steps carefully:\n1. Insert the OLED Display in the case slot.\n2. Wire the Display and make shure the connections are right between the PCB and OLED (Pinout may vary).\n3. Connect the motor or light wires (Black and Red) to the output terminal block, it doesn't matter the polarity.\n4.", "472" ], [ "Bi Flasher With and Without Microcontroller\nIntroduction: Bi Flasher With and Without Microcontroller\nHey Everyone Whazzup!\nSo you want to make a PCB Badge and in that badge, you want to add a simple Two LED Flasher circuit in which Two LEDs will turn HIGH and LOW simultaneously.\nThis task can be done quite easily with or without a microcontroller.\nUsing a Microcontroller is good but for such a minimal task, a timer ic could also be used here which would save a lot of costs.\nIn this Instructables, I'm gonna show you guys how you can use a Microcontroller (Arduino Nano and Attiny13A) and a simple Timer IC Setup to make a Bi Flasher with minimal stuff and Low cost.\nLet's get started\nSupplies\nI will use two types of setups in this project so the following are stuff required in both setups.\nMicrocontroller Setup\n* Attiny13A\n* LED Red and Green\n* Power Source (can be anything, coin cell, 3.7V battery, Bench Power supply)\n* Arduino as ISP Programmer setup\n* Breadboard\n* jumper wires etc\n555 Timer IC Setup\n* 555 Timer IC\n* LED Red and Green\n* 22uf Capacitor\n* Power Source (can be anything, coin cell, 3.7V battery, Bench Power supply)\n* 68k ohms 1/W Resistor\n* 1K Ohms 1/W Resistors\nStep 1: Procuring Materials\nAs for the Source from where I get most of these components, I got the Timer ICs, Attiny13, LEDs, Resistors, and capacitors from ALLCHIPS.\nALLCHIPS is a well-known Platform For Electronic Components Supply, they have everything that you need for any type of project. They are an all-in-one procurement department of hardware manufacturers as all components I used in this project were provided by ALLCHIPS which was a cool and helpful thing!\nAlso, they have this BOM IN ONE BOX thing which is such a helpful thing, we provide them a BOM List and they procure all the components and deliver them \"IN ONE BOX\" which is an efficient way of purchasing components for any project!\nCheck out ALLCHIPS for more info.\nStep 2: Getting Started\nBefore Setting up both versions of a Bi Flasher circuit, let first see where and how we can use Bi Flasher setup.\nI've been making some PCB Badges recently, these PCB Badges are a combination of Art and Electronics in which we add some artistic elements on a PCB like a character from anime or movie or just a few patterns.", "982" ], [ "we also add LEDs on these badges to illuminate certain aspects of that added character or pattern.\nFor example, I made a C3PO PCB Badge from Starwars.\nI've placed LEDs in his eyes and to control these LEDs, I have used the Bi-Flasher setup which is based on 555 timer IC in the SOIC package.\nWhat I'm trying to say here is, this LED Flashing-Blinking setup increases the impact of the whole Circuit and it also looks pretty awesome. If you want to see the whole Badge making process, check this post of mine-\nhttps://www.instructables.com/Obito-Uchiha-PCB-Bad...\nStep 3: Microcontroller Setup\nLet's first start with the easiest method in the Book which is to utilize a microcontroller to control LEDs.\nThe first choice here would be an Arduino board connected with two or more LEDs. This one is by far the easiest set up to make such projects.\nWire the LEDs with Arduino Nano in this way.\n* D3 to VCC of GREEN LED\n* D2 to VCC of RED LED\n* GND of Both LEDs to GND of Arduino\nStep 4: ​Here's the Code for Chasing/Bi Flashing of Two LEDs.", "854" ], [ "<PERSON>\nIntroduction: <PERSON>\nHey everyone what's up!\nSo this is the Jack O'Speaker which is a Bluetooth Speaker crammed into a Jack O'Lantern.\nIn this case, the Jack O'Lantern is 3D Printed and made out of Orange PLA instead of Pumpkin.\nI could make this out of an actual Pumpkin but it won't last long so a better idea is to make the whole thing from Plastic.\nInside this Jack O' speaker, there's a 40W Stereo Bluetooth Amplifier Board connected with a 4 Ohms speaker powered by a 12V Lithium-Ion battery pack.\nThe goal or motivation for making this Speaker was to prepare a Halloween-themed BT device that can be kept anywhere at the home, and we can play creepy music on it to add some ghostly vibe in the air.\nAlso, this setup is loud because of the higher wattage the speaker draws as I'm using a super kool speaker which has been salvaged from an old Home theatre system.\nIn this Instructables, I'm gonna show you guys how I made this project in few easy ways.\nSo let's get started!\nSupplies\nStuff I used in this built-\n3D Printed parts\n* Pumpkin Model made from Orange PLA\n* Pumpkin Upper part made from Green PLA\nOther Stuff\n* Audio Module\n* Battery Pack 12V 5.2Ah (with BMS attached)\n* 3mm LED\n* 10K Resistor\n* Diode IN5399\n* DC barrel jack\n* Rocker Switch SPST\n* Wires\n* M3 Screw x4\n* Speaker 8Ohms\nStep 1: Prologue\nAudio Module\nNow the Heart of this project is the Audio Bluetooth Amplifier module which is this \"XY-P40W\".\nThisModule can work between the Voltage of 5V and 24V but I will be using a 12V Lithium-Ion battery pack to powering this module.\nThis module runs Bluetooth 5.0 and has dual speaker output.\nAlso, the output power of the setup I'm using is around 20W which is with a 4 Ohms speaker at a 12V Power source.\nIt comes with a Volume Adjusting knob but I won't be using that in this project.\nI got this module from PCBWAY's Giftshop, link is here- https://www.pcbway.com/project/gifts_detail/Stereo...\nSpeaker\nAs for the Speaker, I'm salvaging a great speaker from my old home theater set.\nThe Speaker I'm using is a 4 ohms woofer and its built quality is just awesome. I have a total of 10 speakers with me so i will be making a bunch of these Pumpkin speakers I guess. (image is attached of the whole home theater system which I bought in 2010)\nAnyway, a normal 4 Ohms speaker will work as well, if you want to make this project then you need to edit the mounting holes for the replacement speaker.\nStep 2: PLAN\nThe plan here is simple, Jack O'Lantern shape will contain or house the Speaker, Audio Module, and Battery Pack.\nI will be adding a switch between the battery and the Audio module for turning the setup ON\\OFF.\nAlso, for charging the battery pack, I will add a DC Barrel Jack with an IN5399 Diode in series and an indicator LED that will indicator the charger Plugged IN.\nAs for the 3D Printed part, I will be using the generic pumpkin shape and modify it for BT Speaker conversion.\nStep 3: CAD Design\nTo start this project which involves a Pumpkin Model, I have to model a pumpkin.\nUnfortunately, Modeling a pumpkin is a very long process but you know what's easy and really a good tool for this kind of stuff, Tinkercad.\n* From the Tinkercad's Part library, I selected the Jack O'Lantern Model and then set its dimensions as required.\n* Then I exported the Pumpkin Model from Tinkercad to Fusion360 Directly as both of them are Autodesk products and hence they are connected so we can send any file made in Tinkercad to Fusion360 which is a cool feature.\n* In Fusion360, I first cut down the Top side of Pumpkin so I could add a speaker inside it.\n* For Elevating speaker position a little bit I added a part between Base Pumpkin Speaker. (later I made this part from green PLA which gives this project nice dual-color contrast)\n* AfterFinalizing the Model, I exported its 3mf file for 3D Printing.\nStep 4: 3D Printed Parts\nAs for the 3D Printing settings and color profiles, I used two kinds of PLA in this project.", "485" ], [ "PALPi Retro Game Console\nIntroduction: PALPi Retro Game Console\nHey everyone what's up!\nSo this is my RecalBox based handheld gaming console aka the PALPi\nIts name is PALPi because it uses a composite PAL Display.\nWhen I was little I love playing games like Pokemon, contra, super Mario, Final Fantasy, and other games mostly on Gameboy advance and that game console that we hooked up with our CRT TVs to run great old stuff.\nWell, nowadays we can just download the retro game ROM and open it up in an emulator and play that game on our laptop and mobile devices.\nBut as a maker, I wanted to do something different, so I prepared this handheld retro gaming console setup which is powered by a Raspberry pi zero, the OS that I'm using here is the Recalbox os. It's a decent Emulator OS that also comes with few preloaded games.\nThis whole setup is powered by an IP5306 IC which is a 5V 2A Constant Boost IC. It's used in a power bank circuit which is ideal for powering a Raspberry Pi zero.\nIn this Instructables, I'm gonna show you guys how you can set up this gaming console and make a Complete handheld Gameboy that can emulate any retro game that you can imagine.\n(Also, the First Half of this project contains the breadboard version and the second half contains the PCB Edition)\nSupplies\nMaterial Required\nThese are the things that we need for this build\n* Raspberry pi zero\n* 16GB memory card (8GB will work as well but I wanted to add many games in it so I choose this instead)\n* TV\n* HDMI to micro HDMI adaptor\n* 5V 2 A Charger/ PowerBank that can output stable 2A\n* keyboard\n* USB to micro USB adaptor\n* RecalBox os image file/ Raspberry Pi Image Flasher\n* Regular Pushbuttons\n* Custom PCB\n* IP5306 IC\n* 10uf 0805 Capacitors\n* USB Port\n* USB Micro Port\n* Li-ion Battery with CON2 Connector wire\n* CON2 Connector\n* 10k 0603 Resistance\n* 2R 0805 Resistance\n* Vertical Push Button\nStep 1: Basic Setup\nThis is what I want to make, a cliche Gameboy layout.\nI'm using a 4.3-inch display in this setup which is pretty huge if compared with a regular Gameboy screen so this setup size will be around 135mm x 140mm. On the front side, there's a display and buttons and on the bottom side, raspberry pi zero along with a boost converter circuit and a Li-Ion Cell will be placed.", "848" ], [ "This Setup is a combination of PCB and 3D Printed Body which will be connected together via screws through the given mounting holes in the PCB.\nStep 2: Setting UP the RecalBox\nIf Raspberry Pi is the Brain of this Project, then the RecalBox is the Heart.\nI'm just making Hardware for this setup, there are already a bunch of other similar Gameboy stations based around Recalbox OS. The reason for that is simple, setting up RecalBox is a pretty easy thing to do and we only have to tweak few things in the OS to make certain things run. Here's how you can install the Recalbox for your raspberry pi!\n* Download the Raspberry Pi imager.\n* Select the right OS for your device, which would be RecalBox\n* select your system which is Rpi0\n* Raspberry pi imager will do your work of downloading and installing the RecalBox on the memory card.\nAfter installing the RecalBox os, you need to plug your Raspberry pi setup with a TV and a Keyboard.\nAfter booting the whole setup, our RecalBox works like a normal emulator.\nStep 3: Schematic for Basic GPIO Wiring\nThis is the schematic that we have to use for GPIO Buttons. The buttons work when we pull down any GPIO Pin to GND.\nStep 4: Display and GPIO Controls\nLet's talk about external display now, because this project apparently has 2 hearts, the second heart is the display.\nwhen it comes to displays, we can find a bunch of them, both for HDMI ports and the ribbon cable one. they all work perfectly well but for this project, a 30$ display is not ideal so I bought a cheap car monitor which has a composite PAL Port.\nYes, I'm using a composite PAL Port here, I'm making a retro gaming console and the FPS is not really an issue here so composite is now my best friend, friendship ended with HDMI Port.\nBefore Hooking up the Car Monitor with Rpi, there was a small problem.\nCar Monitor works with 12V and we require a 5V or 3.3V Display.", "848" ] ]

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[ [ "‘Who Has the Most Selfies?’ Council of Bloggers Meets for First Time in Russian Parliament · Global Voices\n<PERSON> speaks at the first meeting of the Council of Bloggers in Russia's lower house of parliament. Source: YouTube.\nWithin days of announcing the creation of a “Council of Bloggers” in Russia's lower house of parliament, State Duma MP <PERSON> had put together an impressive guest list for the first meeting: <PERSON> extended invitations to 25 influential writers and videobloggers, including opposition leader <PERSON>, <PERSON> (<PERSON>), <PERSON> (<PERSON>), kamikadze_d (<PERSON>), and <PERSON> — it was a veritable who's who of the Russian blogosphere.\nThe only problem was that all of them RSVP'd “no” to the June 19 meeting. Indeed, none of the influential or controversial bloggers invited actually showed up to the meeting, which was instead attended by pro-regime or apolitical bloggers. (Watch the full meeting here.) The bloggers who did attend included <PERSON>, the author of the “Lisa Drives” car testing videoblog; firebrand Liberal Democratic Party of Russia leader <PERSON>; and <PERSON> (the daughter of Kremlin Press Secretary <PERSON>), whose online presence quite limited outside of her Instagram feed, which features glam shots of her taken across Western Europe.\nUnsurprisingly, <PERSON> made sure to ‘gram from the Duma:\nНакануне, в прямом эфире РБК шла дискуссия о том, что власть не слышит молодежь, а несколько недель ранее я писала о том, что не понимаю, что наша Московская мэрия делает с тротуарами и с организацией движения в центре Москвы. Пускай, не со всем можно согласиться, но сам факт, что мне ответили меня поразил. Я хочу сказать СПАСИБО за ответ.", "880" ], [ "Все действительно зависит от нас и нашей способности вести диалог.\nA post shared by nomade. Elizaveta. me cool (@stpellegrino) on Jun 19, 2017 at 7:48am PDT\nWithout opposition voices, the meeting's conversation frequently veered into the absurd: Instead of discussing popular blogosphere topics like corruption or nepotism, <PERSON>, for example, asked <PERSON>, the co-founder of the magazine “Selfie,” who in the room had posted the most selfies online. <PERSON> replied, “probably Elizaveta,” which <PERSON> objected to. “I generally take selfies only rarely. Two or three weeks ago I posed my first selfie in half a year.” Not to be outdone, <PERSON> joked: “I have more than ten thousand. Who has more than me? No one!”\n<PERSON>, a popular blogger who declined to attend the event, speculated that the Kremlin had arranged the Council of Bloggers in response to the anti-corruption protests that have swept across Russia over the last three months, in part powered by influential bloggers posting on social media.", "880" ], [ "Russian Media and Internet Users Debate the Ethics of Reporting on Teenage Suicide · Global Voices\nThe investigation of mysterious groups on VKontakte full of images of whales and butterflies that Novaya Gazeta claims drive teenagers to take their own lives has met with public criticism. Image from VKontakte.\nWhales. Butterflies. Rina. f57. These words, images, and names have been circulating on the Russian media and social networking sites this past week after independent newspaper Novaya Gazeta published an article exposing groups on VKontakte that allegedly promote suicide. Since May 16, the Russian Internet has been buzzing with what media website Slon.ru called the “most important newspaper text of 2016.” But not everyone is thrilled with the investigation, with users questioning its ethics, its conclusions, and its methods.\nOn May 16, Novaya Gazeta reported on an investigation into 130 alleged teenage suicides that occurred between November 2015 and April 2016 in Russia. All of the victims, Novaya reporters said, were members of the same groups on Russian social network VKontakte, dedicated to themes of suicide or self-harm, and often posting shocking content.\nNovaya Gazeta's investigation, titled “Groups of Death,” warned parents to read the findings “so that they could save their children from risk” and so that they could learn to identify the slightest details of looming tragedy and teach it to other parents. Some RuNet users found the reporters’ stance biased and their tone as bordering on the cusp of hysteria.\n“Groups of Death 18+”\nSecret, private groups on social media that entice teenagers to take their own lives. Sounds like the plot of a bizarre horror movie. And yet hundreds of these groups are allegedly active and thriving on VKontakte.", "534" ], [ "“Who are these people?” asked Novaya Gazeta. “Spiritual freaks, maniacs, Satanists, fascists?”\nAs the investigation, now picked up by other news outlets and Internet users, continues, the administrators of these groups emerge as seemingly regular members of society. <PERSON>, the main administrator of the most popular group “f57” , is a 21-year-old sound engineer living in the greater Moscow area. At this point in the investigation, he is hailed as the main orchestrator of content allegedly meant to incite suicide, including videos of his own (obviously fake) suicide, images of self-mutilation, and poems lamenting the bitter cruelty of being alone in the world.\nТебя бросил парень?\nУстала от учёбы?\nЧасто сидишь в Вк?\nНикто не пишет?\nЗагляни в Темная сторона меня, там кое-что есть для тебя\nBoyfriend broke up with you?\nTired of studying?\nAlways hanging out on VKonakte?\nNo one writing to you?\nTake a look at My dark side [page], maybe there is something for you there\nOn the surface, this looks like a disturbed individual (or individuals) trying to lure a bunch of teenagers into a weird Internet cult. But what precisely about these groups caused so many teenagers to join and then, allegedly, take their own lives? That's where <PERSON> comes in.\n<PERSON> is a 16-year-old girl from Russia's Far East who took her own life in November 2015. The community administrators circulated her last selfie before her death captioned “Meow. Goodbye,” as well as her postmortem pictures and screenshots of her text messages. As a cult of personality started around <PERSON>, teenagers across the country began stalking her VKontakte page, reposting her statuses, music, pictures. “<PERSON>, you are the best,” users scrawled on her wall. “It's such a shame that I never knew you. You're my hero, I love you, you have the most incredible eyes, like you just appeared to us out of an anime.”\nIn addition to encouraging the cult of personality, administrators circulated pictures of whales and butterflies, allegedly claiming that these symbols represented anguish and loneliness. Whales are the only animals known to die by suicide by beaching themselves when they are “in despair.” Many butterflies only live for a day.", "880" ], [ "‘Buy a New SIM Card’ and Await Further Interrogation: Russia’s Security Services Detain and Question a Reporter · Global Voices\n<PERSON>, a member of the independent Journalists’ and Media Workers’ Union, pickets the headquarters of Russia's domestic security agency FSB, to protest against a colleague's detention. Photo by <PERSON>, used with permission.\nWhen state security officers arrived at his home early in the morning of January 31, Russian journalist <PERSON> learned firsthand that punishment is not always timely.\n<PERSON>, a co-chair of the Journalists and Media Workers Union in Russia, was visited by members of the FSB, one of Russia’s security services, who searched his apartment and seized several of <PERSON>'s possessions including laptops, documents and copies of his independent magazine, Moloko Plus.\nPosting on his channel on Telegram, a widely-used messenger service in Russia, <PERSON> told his subscribers that the search was related to Article 205.3 of Russia's criminal code, a statute that deals with “undergoing training for the purpose of committing terrorist activity.” This was confirmed by a lawyer from Open Russia, an organization dedicated to the promotion of democracy and human rights in the Russian Federation.\n<PERSON> also took to Twitter to tell everyone the reason for the visit:\nУ меня обыск. Доброе утро. В рамках текста в The new times. Телефон отбирают.\n— паша никулин (@mrzff) 31 января 2018 г.\nThey’re searching my apartment.", "880" ], [ "Good morning. For my article in The New Times. They’re taking away the phone.\nThe article in question, “From Kaluga With Jihad”, drew on an interview <PERSON> had conducted with a Russian national from the Kaluga region, who went to Syria to fight for the Al-Nusra Front, a splinter faction of al-Qaeda. When it was published in March of 2017 in The New Times, the interview immediately drew the attention of the Russian authorities.\nRoskomnadzor, Russia's media regulator, issued a warning to The New Times for “signs of justifying terrorism” in the interview. The piece was later removed from The New Times’ website.\nAs The New Times’ chief editor later wrote on Facebook:\nПутин публично говорит о том, что тысячи россиян воюют за ИГ, а писать о мотивах, почему русский парень из Калуги принимает ислам и уезжает воевать в Сирию — это „признаки оправдания терроризма“! По мне так это классическая цензура, которая запрещена Конституцией.\n<PERSON> publicly says that thousands of Russians are fighting for the Islamic State, but writing about motives, why a Russian guy from Kaluga accepts Islam and goes off to fight in Syria is “signs of justifying terrorism”! I feel this classic censorship, which is banned by the Constitution.", "880" ], [ "Saying Goodbye to <PERSON>, Godfather of the Russian Internet · Global Voices\n<PERSON>. Source: Facebook.\n<PERSON>, a founding father of the Russian Internet, successful media entrepreneur, and popular blogger, died of a heart attack on July 9 while staying at a friend's summer house outside Moscow. He was 51 years old.\nOften referred to as the “Godfather of the Russian Internet,” <PERSON> founded or led influential news websites Lenta.ru, Gazeta.ru, Vesti.ru, and NTV.ru (now NewsRu.com), and helped popularize blogging in Russia.\n<PERSON>, who described himself as the “planet's first Russian blogger,” helped sound the alarm as the <PERSON> regime began to crack down on the RuNet after allowing the Internet to operate relatively freely during the first 13 years of his tenure.\nHe was a tireless advocate for free speech in Russia, sometimes getting himself in trouble for his own firebrand politics: Last year, <PERSON> was fined 500,000 rubles, or $8,000 for calling for Syria to be “wiped from the face of the earth.”\nIn the hours since his death, Russian bloggers, journalists, and media personalities have shared their memories of <PERSON>, whom they remember as a dogged worker who built the RuNet from the ground up, helping turn it into, in his own words, “Russia’s only territory of unlimited free speech.”\n<PERSON>, the founder of VKontakte and Telegram, wrote in a post on VKontakte on Sunday that <PERSON> had “until his last days, stood in defense of the Internet and common sense in his precise and vivid posts on LiveJournal,” where <PERSON> blogged. He continued:\nАнтона будет не хватать.", "880" ], [ "Он был одним из тех редких людей, кто ясно мыслил, ясно излагал, охотно делился своими знаниями и оставался оптимистом. Он всегда поддерживал меня и многих других, а мы часто забывали поддержать его в ответ.\nК сожалению, мы уже не сможем вернуть Антону ту теплоту, которой он делился с нами. Но мы можем хранить память о нем и защищать те принципы, которые он защищал, и следовать его примеру – поддерживать друзей, делиться знаниями, сохранять оптимизм и здравомыслие.\n<PERSON> will not be forgotten. He was one of those rare people who thought clearly, expressed himself clearly, and willingly shared his knowledge and remained an optimist. He always supported me and many friends, but we regularly forgot to support him in return.\nUnfortunately, we can't give back that warmth that <PERSON> gave to us.", "417" ], [ "Who’s Paying for the Meme War Against <PERSON>? · Global Voices\nA paid-for meme critical of opposition leader <PERSON>.\nOn May 5, the administrators of multiple major public groups on the Russian social media website VKontakte began receiving offers of payment to post memes criticizing opposition leader and political blogger <PERSON>.\nThe meme scheme became public when a VKontakte community called “Abstract Memes for Elites of All Sorts” published a post that included screenshots of the pay-to-play offer. The person —or people — responsible for promoting the content identified themselves only as representatives of an “advertising agency,” and had ready-made memes available for distribution. They asked the VKontakte group administrators to write text to accompany the memes, and promised to pay between 700 and 900 rubles ($12-15) per post per day.\nThough it remains unclear who is behind the memes, the scheme comes on the heels of an April 18 report by television station Dozhd about a major mudslingling campaign that the Kremlin was reportedly planning against <PERSON>. Just days later, an anonymous user published a video on YouTube comparing <PERSON> to <PERSON>, which many interpreted as being part of a larger attack against the opposition presidential candidate.\nIn a series of messages exchanged with the administrators of “Abstract Memes,” the alleged advertising agency representatives confessed that they disliked “Nashism,” or the kind of political tactics that the now-defunct pro-Kremlin youth movement “Nashi” used to employ, and that they were only doing it for the money.", "534" ], [ "They also said that two other groups, “Borscht” and “iFeed” had already agreed to distribute the memes, though no anti-Navalny material has appeared on their feeds in recent days.\n“Is <PERSON> a Kremlin Agent?” Source: https://vk.com/nauka_magik.\nThe administrators of several groups ultimately did post several of the anti-Navalny memes that had been sent to “Abstract Memes.” The group “The Illusionist,” which has more than 2.2 million followers on VKontakte, posted a meme on the evening of May 5 that looked like a magazine cover and read: “Is <PERSON> a Kremlin Agent?”\nAnother group, “Cool Science, Tricks, and Magic,” which has only 4,800 members, posted the same image the following morning.\nOne meme proposed by the advertising agency depicts <PERSON> as a magician impressing a group of hamsters by turning “speculation” and “falsehood” into grapes. The VKontakte community “You Won't Believe It,” which has more than 6.7 million subscribers, initially posted the meme but had deleted it by May 7.\nThe website Meduza reported that other VKontakte groups, including “Evil Chaplin” and “Decaying Europe,” had also published anti-Navalny memes, though they have likewise been deleted.\nThe brief anti-Navalny meme offensive seems to have hurt VKontakte groups more than it helped them: Roughly 1,600 users unsubscribed from “Decaying Europe,” and around 1,400 left “The Illusionist,” according to Meduza.\nСтатистика одного из таких сообществ. Кажется, народу не понравилось pic.twitter.com/lqD6mLHwtt\n— Лентач (@oldLentach) May 6, 2017\nStatistics [showing the number of unsubscribers] from one of these online communities. It seems that the people didn't like [the memes].", "880" ], [ "Russia: Retired Tennis Star <PERSON> to Run for Parliament · Global Voices\nThis post is part of our special coverage Russia Elections 2011.\nRussian tennis phenomenon, <PERSON>, has announced that he will run for the Russian State Duma in the December 4 elections. Born in Moscow in 1980, Mr. <PERSON> began his professional tennis career in 1997. In 2000 he became the number 1 ranked player in the world when he defeated <PERSON> in order to win the US Open. He won the Australian Open in 2005 and helped lead the Russian team to Davis Cup victories in 2002 and 2006.\nCertainly, Mr. <PERSON> is a talented athlete. However, his public image, as illustrated by citizen media outlets, has until now not been focused on public service.\nRussian Politics for Dummies Blog announced Mr. <PERSON>'s campaign in a post on October 28:\n<PERSON>, the 2000 US Open winner and 2005 Australian Open champion, said he was serious about his political ambitions.\n“I am running for Federal Parliament in Russia,” <PERSON> told the ATP Champions Tour website.\n“The elections are on December 4th so I will find out soon. It’s a new challenge. I think I am an intelligent guy and I have a lot to bring and a lot of ideas about things and what to do. I am very committed to it.”\n<PERSON> added: “I could be the best looking guy in the Duma, but that’s only because all the other guys are over 60.”\n<PERSON> at the XV International ATP tennis tournament St. Petersburg Open 2009. Photo by <PERSON>, copyright © <PERSON> (27/10/2009).\nRussian blogger, <PERSON>, contrasted his admiration [ru] for Mr. <PERSON>'s athletic ability to his distaste for Mr. <PERSON>'s antics in an August 2011 post:\n[…] I must say that I play tennis a bit myself, and for a long time <PERSON> was a man I admired. His graceful game sometimes reminded me of a tiger. However, I was always annoyed by his antics with the smashing of rackets, etc.", "880" ], [ "Honestly I do not know what he needs politics for. Maybe just because it's trendy. […]\n<PERSON>, GlobalPost blog's senior correspondent in Moscow, placed Mr. <PERSON>'s State Duma run into political and geographical context in her July post:\nWhat does somebody like <PERSON> do after retiring from tennis? There are plenty of options: he could model, he could act, he could marry me, I mean, somebody.\nBut this is Russia and if you want to stay on top here, best to link up with United Russia. And guess what – that’s what <PERSON> is doing.\nAccording to the United Russia website, <PERSON> is taking part in the election primaries currently being held in consort with the People’s Front (I wrote about them this weekend). The idea is to formulate United Russia’s candidate list for the December elections. <PERSON> is standing for the Nizhny Novgorod region, which is weird, considering he was born in Moscow, to ethnic Tatar parents, and Nizhny has nothing to do with either one or the other. […]\nMr. <PERSON>'s own 2006 blog – which is hosted in Russian here and translated into English on the ATP World Tour site – offers insight into his life as a tennis player. In one blog entry, he discussed his relationship with his parents:\n[…] Last night my father called me at around 1am and asked me to use one of my cars to take my grandfather to a medical check this morning. Since I am a good son, I told him to come to the apartment in the morning and pick up the keys. When he arrived, I gave him some laundry as a present for my mum…\nFor some reason, after a certain age our lovable parents enjoy doing things for their kids, like laundry, looking after your flat when you are not around. They are just happy to do anything, anytime for their kids. But when you are young, you have to do all these things, laundry, doing the dishes, cleaning the apartment and all the c—p you hate doing, when the only thing you want to do is go out, hang out with your friends and do whatever is on your mind. Every age has its good parts and bad parts, it is important that you enjoy both of them. […]\nAnd here are Mr. <PERSON>'s thoughts about what it is like to participate in a tennis tournament:\n[…] The day was long, the ladies took over on court and they took forever to decide who wanted to win and lose.", "148" ], [ "The Kremlin Is Worried Attacks on Opposition Leaders Are Making Them More Popular · Global Voices\nSource: <PERSON>, Twitter\nDays after opposition leader and presidential candidate <PERSON> was again doused with green antiseptic on his way to an event in Moscow, the news website Gazeta.ru reported that the Kremlin had instructed regional authorities to crack down such attacks in the future.\nGazeta.ru quoted a source in the Kremlin as saying that attacks on <PERSON> and other oppositioners with “brilliant green” antiseptic— known as “zelyonka” in Russian —are giving the opposition free press and helping to raise its profile across the country. “In fact, attacks are only increasing their popularity.” Law enforcement authorities will be encouraged to crack down on the attacks and punish perpetrators, the source said.\nA campaign ad for <PERSON>\n<PERSON> was hospitalized on Thursday after an attacker poured zelyonka on him outside his office in Moscow. On Sunday, he wrote on his website that he is still treating his right eye, which was sprayed during the attack, and that he is worried that he may lose some vision.\nZelyonka attacks have become so frequent in recent months that bright green has become the unofficial color of <PERSON>'s 2018 presidential campaign and the broader <PERSON> opposition. <PERSON>'s supporters have painted their faces green in solidarity and tried to use the attacks as a way to mobilize volunteers.\nAccording to one of Gazeta.ru's sources, a recent attack on the popular blogger <PERSON> in the southern city of Stavropol on April 26 was the “last straw.” In the days since the attack, law enforcement authorities have rounded up five attackers—though <PERSON> says that ten people were involved.\nВсем привет pic.twitter.com/tyUNBzatQV\n— Илья Варламов (@varlamov) April 26, 2017\nHey, everyone!\nStill, the attacks don't appear to be slowing down.", "880" ], [ "Yesterday, the popular blogger <PERSON> was attacked by men in the city of Samara.\nYesterday in Yekaterinburg, some thugs followed @itema_Tv after he left an <PERSON> protest, cornered him, & sprayed him with antiseptic. pic.twitter.com/Cnyg5jbKpb\n— <PERSON> (@KevinRothrock) April 30, 2017\n<PERSON> wrote on his blog on Sunday that the Kremlin was behind the attacks on him, an accusation one of Gazeta.ru's sources flatly denied. Gazeta.ru's report calls into question the notion that the attackers are acting on instructions from local or regional authorities, however. In particular, one source called attention to the fact that many of the perpetrators who have been identified come from regions neighboring where they carry out the attacks, suggesting that they are centrally coordinated.\nAnother source, meanwhile, said he believed the attackers were acting independently and out of a sincere belief that <PERSON> and other members of the opposition are harmful to the state.\nВ Администрации президента не знают кто плеснул зеленкой Навальному в глаза pic.twitter.com/r4J5Capz24\n— <PERSON> (<PERSON>) April 30, 2017\nThe Presidential Administration has no idea who sprayed green antiseptic in <PERSON>'s eyes.\nThe Kremlin's concern that the attacks are raising the opposition's profile comes amidst a surge in <PERSON>'s popularity: nearly 100,000 volunteers have signed up to work on <PERSON>'s presidential campaign, suggesting that his political movement may be more popular than many initially thought.\nParty Membership:\nUnited #Russia: ~2 mln\nCommunists ~150K\nLDPR ~180K\nJust Russia ~410K\nYabloko: ~50K\nRegistered @navalny volunteers: ~95K\n— <PERSON> (@fa_burkhardt) April 30, 2017\nAnd indeed, <PERSON>'s anti-corruption message seems to have increasing purchase with Russians. On March 26, tens of thousands people joined nationwide anti-corruption protests organized by <PERSON>, the largest anti-government demonstrations in Russia since 2011-12.", "880" ], [ "Russia: <PERSON>, the Quintessential ‘New Russian’ · Global Voices\nBillionaire <PERSON> serves as an example of the quintessential ‘New Russian’ through his controversial activities during the Yeltsin Era, his modern business practices, and his extravagant international spending – he has just purchased the most expensive New York City apartment to date.\nGlobal Voices placed Russia's ‘oligarchs’ in their historical and economic context in a November 2011 post entitled, “FC Anzhi and the Yeltsin Era Money”:\nEver since the fall of the Soviet Union 20 years ago, the world has watched Russia's transition into capitalism with great interest. The <PERSON> era of the 1990s was characterized by a struggle over who would emerge from the transition with holdings of Russia's major sources of wealth, such as its natural resources. The victors in that struggle are known as the ‘oligarchs’ because they possess a degree of wealth that surpasses most people's ability to conceptualize.\nAnother term for those who emerged from the process of privatization with vast amounts of wealth is ‘New Russians.’ While the term ‘Oligarchs’ focuses more on the political power of these individuals, ‘New Russians’ emphasizes the economic component of their influence.\nToperJokes Blog – a site that translates Russian and Ukrainian jokes into English – devotes an entire folder to jokes about New Russians. Here is one:\nA New Russian asks the priest:\n– Father, my cat has died. I want you to read the burial service!\n– No, we may not do this in Orthodox Church.\n– What should I do then?\n– Across the road there is a sectarian church, they will do anything for money.\n– Will 4000 dollars be enough?\n– My son, why didn't you tell from the start that you had a baptized cat?!\nAs this joke suggests, New Russians are also characterized by an often unspoken assumption that their wealth was acquired through the use of irregular methods. During any governmental transition there will invariably be periods of time when laws are vague or non-existent. Russia has yet to develop a comprehensive land registry, and so it is little surprise that the Moscow News estimated last fall that 90 percent of Moscow apartments are rented illegally.\nAnalyseman Blog discussed [ru] Mr. <PERSON>'s activities during the <PERSON> era, including the 11 months he spent in prison accused of murdering a factory executive:\n“In the early 1990s, <PERSON> was one of the most active participants in privatization in his region. Mr. <PERSON> then headed Perm Credit Bank FD and bought shares mainly in the chemical plants.", "880" ], [ "In 1992-1993, first deputy chairman of the Perm region's Property Fund, <PERSON>, helped him to privatize a major stake in Uralkali and became his partner. In 1996, both were accused of organizing the murder of the director of the Perm factory Neftekhimik. Mr. <PERSON> spent 11 months in pre-trial detention and was released on 1-billion bail.” – a little bit of background on how the money [spent on the New York City apartment] had been made.\nOther casualties of regime change are issues of safety regulations and infrastructure. The Russian-language MCINC LiveJournal blog discussed [ru] last week how Russian factory owners are not held accountable for accidents, but rather they continue to receive monetary benefits from the state.\nSuch practices were exemplified by a major accident that occurred in Mr. <PERSON>'s Uralkali factory in 2006. UralKali.com released the Russian government's official findings on the cause of the accident along with the company's legal obligations regarding paying damages to the victims:\nUralkali (Berezniki, Perm region) has received the report of the re-opened investigation into the causes of the accident that occurred at Uralkali Mine 1 in October 2006. As stated previously, the second investigation was conducted by a commission established by Russia’s mining safety watchdog, Rostekhnadzor, on November 11, 2008, by order of the Russian Deputy Prime Minister <PERSON>. […]\nThere has to date been no judicial decision requiring Uralkali to reimburse the expenses listed in the report. However, the company cannot give any assurance that claims will not arise for such reimbursements, which could exceed 3.1 billion rubles.\nSo then the question becomes – What do New Russians do with the money?\nThe aforementioned Global Voices article about <PERSON> FC Anzhi, along with one pertaining to <PERSON> New Jersey Nets, discuss how many New Russians buy international sports teams.\nCoincidentally, it was to Mr. <PERSON> that Mr.", "704" ] ]

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[ [ "Farradays law or lorenzt force\nA student in my physics class posted, in a group, a wrong answer to a question.\nThe situation was: A plane has a wire extended between the tips of its wings and flies through a magnetic field, perpendicularly, while accelerating.\nThe question was: What will be the induced current?\nHis answer was 0, and he explained that as the plane was flying through a uniform field, there would be no change in Magnetic flux density, so no change in flux linkage and ultimately no induced current.\nI stated, after clarifying with a question on here earlier today, that instead of consulting <PERSON>'s laws, he should think about <PERSON>'s left hand rule.\nMy teacher told me I was wrong, and said as the plane is accelerating, it cuts the field lines at a greater rate, so according to <PERSON>'s law, a voltage will be induced, but he also says this voltage will be increasing.... Even if it was <PERSON>'s laws, as this acceleration was constant, wouldn't the voltage be constant?\nMy next response is a lengthy one:\n<PERSON>'s law dictates proportionality between an induced EMF and rate of change of flux linkage. The rule of a wire cutting through fields lines is contrarily a result of <PERSON>'s left hand rule, where a magnetic force is exerted on the electrons inside the wire that is cutting the field, in the direction of the wire; this leads to a potential difference between both sides of a wire, or induced current for a closed circuit.", "780" ], [ "Also, flux linkage, and thus <PERSON>'s law, refer to solenoids, don't they? Ultimately, the induced voltage will indeed increase due to the increase in the rate at which the wire cuts the field, but this isn't to due with <PERSON>'s law which relates the change in flux linkage on a 2-dimensional conductor. the students understandable reasoning for his answer of an induced EMF of 0 came from him observing that the flux linkage is of constant magnitude, so will have 0 rate of change, no matter the acceleration. Using the left hand rule, and the fact that magnetic force, F, is the sum of the BQv, it can be seen that the electrons will be moved by a greater force, making for a greater potential difference, EMF or current, as the wire accelerates.\nI also realised that with constant acceleration the voltage would be constant, if this was to do with <PERSON>'s law, and will add that to what I have say.\nI'm asking as I want to help this person, while not feeding them false information, wrongfully undermining my teacher and ultimately embarrassing myself.", "780" ], [ "Equation of motion for a coil around a mass, attached with a spring driven by magnetic field?\nFirst of all, thanks for reading and hello! First time poster on Physics Stack Exchange. I'm an electronics engineer (so forgive my poor maths below!) and tend to hang out there.\nI have a questions that's been killing me for a few days.\nI need to design some electronics to control a system which I think looks like the above. It is a linear motor connected to a spring. The motor is of type \"moving coil\", that is, the mass has a coil wrapped around it, within a permeant magnetic field. Some electronics (that I will design) will drive AC current through the coil to make it oscillate at it's resonant frequency.\nI understand how to model the electronic side (a coil in an inductor, with a series resistance and a back EMF).", "780" ], [ "Now, the mass spring is not too hard, there's lots of literature. But, this (I believe) is different - it has an additional 'friction' which is the back EMF generated from <PERSON>'s law (negative of rate of change of flux).\nSo, I tried to model this system (a coil driving a mass spring system). For me, my end goal is a transfer function, in the laplace domain, that is the input (IE, current through the coil, or the voltage across it). As a side note, this is the reason for the modelling, I'd like to see the implications, if any, about controlling this via a sinusoidal voltage (much easier in electronics to deal with) or a sinusoidal current; this can still be done but the electronics is a little more involved.\nEquations of motion\nSo, I think I start of with the <PERSON>'s second law (assuming there's no resistance in the system, other than the back EMF):\n$ \\sum F_x = m \\cdot a_x $\n$ \\sum F_x = F_{spring} + F_{BEMF} - F_{Motor} $\n$ \\sum F_x = -k \\cdot x(t) + \\frac{\\delta \\phi}{\\delta t} - B \\cdot i_{coil}(t) \\cdot L $\nI think the back emf term can be rewritten using the systems coord frame (x pointing right and y point up):\n$ \\frac{\\delta \\phi}{\\delta t} = \\frac{\\delta B \\cdot A}{\\delta t} = B \\cdot \\frac{\\delta ( x \\cdot y)}{\\delta t}$\nSince the magnetic flux is constant, and so is the area of flux enclosed by the coil in the y coordinate, I took these out of the differential. That leaves us with the x coordinate. Lets put a constraint on the system whereby the coil/mass will never be displaced by more than it's full length, $l_x$.", "780" ], [ "confused by explanation of electromagnetic wave in physics textbook\nI'm kind of confused by the proof used in my physics textbook to explain an electromagnetic field using Faraday's law.\nThe text book uses Faraday's law to try to explain why a uniform electric field pointing in the y direction while moving in the x direction must have a uniform magnetic field perpendicular to it pointing in the z direction. The images provided are:\nThe explanation goes on to say that since the application of Faraday's law to the change in size by dA of the imaginary boundary \"efgh\" as the uniform electric field moves in the x direction at the speed of light c for time dt provides a value of $$\\oint {efgh}\\overline{E}\\cdot d\\overline{l}=-Ea$$ for the lefthand side of <PERSON>'s law (since a is the distance from g to h in the image provided and E is parallel to and exists within only that side of the imaginary boundary and in the opposite direction) which is a nonzero value, it must mean that the righthand side of <PERSON>'s law $$-\\frac{d\\phi {B}}{dt}$$ must be nonzero as well.", "903" ], [ "This basically tells us that there must be a uniform magnetic field pointing in the z direction perpendicular to the uniform electric field pointing in the y direction.\nWhile I do understand this explanation, I'm kind of confused because what if the boundary \"efgh\" was drawn like this instead?\nIf this was the case, from my understanding the lefthand side of <PERSON>'s law $$\\oint {efgh}\\overline{E}\\cdot d\\overline{l}=0$$ because the electric field is parallel and exists on (g to h) and (e to f) of the imaginary boundary \"efgh,\" but since it is opposite in direction to the (g to h) side and in the same direction as the (e to f) side, they should cancel out one another. But wouldn't there still be a change in the magnetic flux through the area dA? So it should mean that the righthand side of <PERSON>'s law $$-\\frac{d\\phi {B}}{dt} \\neq 0$$ But this seems to contradict <PERSON>'s law since $$\\oint {efgh}\\overline{E}\\cdot d\\overline{l}=0=-\\frac{d\\phi {B}}{dt} \\neq 0$$ I'm sure there must be something wrong with this approach. What is it that I'm missing? Any ideas?", "903" ], [ "Electromagnetism problem: where does the magnetic field come from?\nConsider the following problem:\nConsider a plane with uniform charge density $\\sigma$. Above the said plane, there is a system of conducting wires made up of an U-shaped circuit on which a linear conductor of lenght $d$ can slide with constant velocity $v$. The system as a whole has a rectangular shape and is parallel to the plane. (See the picture). Calculate the line integral of the magnetic field $\\bf B$ along the perimeter $L(t)$ of said rectangle as a function of time.\nMy professor solves this problem using <PERSON>'s fourth equation in integral form, assuming that the current density $\\bf {J} $ is everywhere null, and that the electric field $\\bf E$ is the one generated by a uniformly charged plane, i.e.", "903" ], [ "perpendicular to the the plane and of norm $E=\\frac{\\sigma}{2\\epsilon_0}$; thus yielding $$\\oint_{L(t)} {\\bf B}\\cdot dl=\\mu_0\\epsilon_0\\frac{d}{dt}\\int_{S(t)} {\\bf E}\\cdot dS=\\mu_0\\epsilon_0Edv=0.5\\mu_0\\sigma dv$$\nI think there are some things wrong both with this solution:\n1. There should be no magnetic field at all! A uniformly charged plane only produces an electrostatic field. (I know there could be a magnetic field generated by the current inside the wires, but then you couldn't assume that $\\bf J$ is null everywhere as my professor did!)\n2. <PERSON>'s fourth equation does not hold in that form if the domains of integration are allowed to vary with time. In fact, by resorting to the differential forms, we find that plugging ${\\bf J}=\\vec 0$ and $\\frac{\\partial {\\bf E}}{\\partial t}=0$, as my professor assumed, yields $rot{\\bf B}=0$, and thus the line integral of the magnetic field over any closed curve, at any istant, should be zero by <PERSON>' theorem!\nTherefore, my question is the following.\nAre the my professor's assumption ($\\bf J$ $=\\vec 0$, $\\frac{\\partial{\\bf E}}{\\partial t}=\\vec 0$) correct, or do both $\\bf J$ and $\\bf E$ need be modified so as to account for the charges present in the circuit? Is there a current in the circuit at all?", "903" ], [ "Why does induced current depend on the area of a loop of wire?\nMy year 12 physics textbook teaches the concept of electromagnetic induction in a rather unintuitive way. Perhaps it is not being thorough. Perhaps I am not being thorough in reading it. Here is my problem:\nThe strength of a magnetic field has so far been described by the Magnetic Flux Density B: the force experienced by a length of current running perpendicular to the field lines. A few right hand rules make this concept grokable.\nBefore proceeding to teach induction, Magnetic Flux is defined as the Magnetic Flux Density multiplied by the area of effect: (|) = B*A. This is already muddying the water: We learn that, in fact, B is an odd kind of density, in that it is measured within an area, not a volume. The word 'Density' usually describes an amount per volume. Even so, the concept of Magnetic Flux is still not hugely difficult to understand.\nThe real problem arises when one starts to speak about induction of current in a loop of wire. \"The induced current in a conducting loop is proportional to the rate of change of flux\". The difficulty is that the amount of flux affecting the wire loop depends on neither the thickness nor (directly) the length of the wire in question, but the area enclosed by the wire: The flux used to decide how much current is induced is that the wire wraps around, rather than some other quantity measured through the region of space that the wire also occupies.\nIt seems odd to me that the space that the wire does not pass through has anything to do with the current induced in the wire.", "780" ], [ "I present a couple of thought experiments that cause me trouble:\n1. The calculation of induced current apparently only works on closed loops: What of half loops? What of straight wires? They cannot be prescribed an \"area\" yet I am sure that they can induct.\n2. Imagine a bar magnet attached to a dart. The dart is thrown through loop of wire the size of a watch face, and the current in the loop is recorded. The experiment is repeated, but with a loop the size of a planet. It is not immediately obvious that a wire that is half a world away should induct more current than one in the same room. The magnet in question hardly produces a uniform magnetic field when stationary; is such a uniform field assumed?\n3. Circular wires have greater loop-areas than equivalently long square wires, Yet the calculation is unaffected by the shape of the loop.\nThe textbook makes no argument as to why the loop's enclosed area is considered. I do not have access to the equipment necessary to test the claims. I am afraid I am missing some bigger picture. So, my question is, why does the area of a loop of wire have anything to do with the induced current (and voltage)? Is there no other, more general, or more intuitive calculation for induction? Perhaps the loop-of-wire calculation is just a special case of this.", "395" ], [ "How do I understand Electromagnetism\nEarlier today I asked about the differences and connections between electric fields and magnetic fields explained to me intuitively, and I was given the answer \"It's complicated and you need to study on your own\", with a link to a wikipedia page on tensors (I hardly understood any of it) and a video of <PERSON> being a condescending jackass. This is not enough of a response for me.\nI want to clear up, first of all, that when I ask for an intuitive explanation, I do not mean \"explain it with a clever analogy\", which is always what physicists assume I mean. An example of an intuitive explanation of an electric field is the following:\n\"Some particles have an electric charge, either + or -. When there are 2 particles with the same charge, they repel each other. Opposite charges attract. However, since there are lots of charged particles in the world, any one charge is effected by multiple other charges at once.", "359" ], [ "Because of this, we use a model called an electric field, which describes the net force a charge will experience at any point in space due to the electric charges of particles in its surroundings. We can also describe a single particle or group of particles as having an electric field. This electric field is the effect that the particle or group of particles has on other charges in its surroundings.\"\nSee? No rubber band analogies, but also no equations with variables and symbols you don't learn about in an intro to physics course. And whenever a vocab word is introduced (like electric field), it is defined, instead of me providing a link to a wikipedia article that uses such cryptic lingo that I would need a bachelor's degree in physics in order to follow in the first place.\nYes, I am bitter.\nAnd I understand that there are questions that can't be easily answered like this. I understand I may need to due research on my own. But where the hell do I start? I've been linked to Wikipedia a couple of times, and that just made things more confusing. And I don't have any intentions of shelling out the money to get a second degree just so I can get an answer.\nWhat do I do? Where do I go to understand it? Are there any sites for this? Any books?", "359" ], [ "Relation between resistance to the flow of fluid, pressure and radius of the vessel\nI just need a clarification, that may seem absurdly easy to some, fair enough, but I am not a physicist and would be glad to hear some answers.\nRegarding blood floow, or any flow through a tube for that matter, it is intuitive that decreasing the diameter or radius of the vessel increases the pressure (since pressure is the force of the particles exterted upon a certain surface area of the vessel wall, F/S). However, we then have resistance that is of course, using analogy with Ohm's law, inversely proportional to flow; Q (flow) = Pressure gradient /R. Bigger the resistance, smaller the flow. However from that same equation Pressure difference is directly proportional to resistance, meaning bigger the resistance bigger the pressure difference - bigger the decline in pressure is. The pressure difference is driving pressure, though, and that is a \"force\" that drives fluid from one end of the vessel to the other. So am I right if I say that, when resistance is increased, the flow decreases but the velocity of the flow increases because of bigger pressure difference (also, conservation of mass and smaller radius since usually resistance increases with smaller radius)? I just need a confirmation of that one, however my real question is as follows.\nResistance according to <PERSON> is inversely proportional to the fourth power radius.", "439" ], [ "So smaller the radius much bigger the resistance, much more decline in pressure. But I also said in the beginning that the pressure increases with decreased radius because of more collisions between particles and vessel walls. This seems like a bit of a paradox to me so I would need a bit explanation for it. I see the same \"contradiction\" in <PERSON>'s equation, where because of total energy conservation, pressure is decreased when velocity is increased (when there is a decrease in radius of the vessel). From a conservation of energy's standpoint that is completely logical however, I cannot imagine pressure decreasing with smaller radius from a \"molecular\" point of view. Thank you in advance.", "439" ], [ "Newtonian Mechanics - How does something like a car wheel roll?\nOk so please bare with me here and what is almost certainly a really stupid question, partly because I don't quite know how to ask it.\nWhen you have a wheel such as one attached to a car, a torque is applied to it from the engine. It's my understanding that the wheel would slide over the road and the car would not move if it were not for static friction which is of course the concept of rolling without slipping.\nThe problems I am having is when I consider what the magnitude of the force exerted on the road from the wheel would be, or specifically the equal and opposite force exerted back onto the wheel from the road via static friction. The reason for this is because I want to say that it is just the torque exerted on the wheel by the engine divided by the radius of the wheel but that seems to lead to a ridiculous conclusion.", "544" ], [ "If I follow that logic, then the equal and opposite force exerted on the wheel by the road, multiplied by the radius of the wheel to get the counter-torque, is equal to the torque exerted on the wheel by the engine but in the opposite direction. That of course would mean that there is no net torque and the wheels would never move (unless the force were greater than that available from static friction but then it would just slip) which means that the car would never be able to move! So simply put, what am I missing that is almost certainly staring me in the face (again)? Clearly things roll and cars move so I know i'm going horribly and embarrassingly wrong somewhere.\nAlso, I often hear people say that static friction is the force responsible for propelling a car forward. How is that the case when it acts in the direction opposite to the direction that the wheels are trying to roll? That's sort of the same question but I think it may help highlight my misunderstandings of rotational motion in this area.\nI never knew wheels could be so complicated! At least for me anyway.", "544" ] ]

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[ [ "There are some assumptions behind Communism that doom it. One assumption is about knowing the world enough to be able to manage things. Another assumption is on human nature and the wanting to be equal.\nThe biggest reason that Communism fails is a lack of knowledge. The communist system is built on assuming that the central authority can know fully. This is a false assumption. A centralized economic planning system fails because it cannot know all the local factors that affect the local economy. Workers cannot properly manage a factory because they don't know all the needs of their customers. And on and on.\nIt is not possible to know all the local issues and how to solve them and know what the future changes will be.", "852" ], [ "Most importantly, it is not possible to know where we need to be investing in order to meet tomorrow's needs.\nThe Marxist vision of workers running the factories and farm hands running the farms is based on an assumption of slowly changing conditions - changing so slowly that workers and farm hands could know the conditions and needs. However, this assumption massively fails in today's world.\nWhat happens is that in a changing environment, some people will learn about situations before others do and will be able to profit from that knowledge. The most extreme cases today include setting up computers where the information about stock trade requests hit those computers before it hits other computers and being able to change prices and / or initiate other trades based on that knowledge.\nThe more centralized the planning, the slower it responds to conditions in the world. (For example, there was a study on emergency response teams for cities / states / countries. The more centralized the control, the more people died in the emergencies.)\nEconomic equality is a noble goal, but it has as an assumption that people want others to be equal with them. That works in some families and fails in others. It works in some tribal groups. But it fails miserably in societies where people do not feel like the rest of society is \"like them\". It fails when some people feel as if they are not part of society.", "998" ], [ "You have a fundamental economic mistake going on here:\n\"The coins contain precious metals and weigh too much to carry more than a few, and the banknotes, while lighter, are big and unwieldy and don't handle folding too well.\"\nYou are basically mixing gold-backed currency with government-backed currency. Today we have government-backed currency. Which means that none of our currency - even the penny - is worth in precious metal value what it's face value us. But you are saying the coinage is \"precious metals\" that is the actual metal of the coin currency has value - while the banknote value of the paper the banknote is on is zero.\nFor currency to exist that has no actual value of the currency itself, you have to have a government around that will back it. This is why coins were used in ancient times - because for example the government of one city would have given zero value to the government of another city. You could, for example, take a wagonload of wheat to 1 city where it was worth maybe 1 gold coin, then take that coin to another city and buy maybe 2 wagonloads of wheat (because in that other city, wheat was more common) and then spend time going back and forth transporting wheat and amassing a large stack of gold coins.", "130" ], [ "(and there were people that did just that)\nBut a scheme like that could not exist if you took a banknote in trade for the wagonload of wheat because when you got to the other city, the banknote would be worthless.\nYou have to either completely dispense with government-backed currency (which means coins and gems only) or dispense with gold-backed currency (coins where the value of the metal is equal to the value of the coin). If you mix the two you will have people melting down coins for the metal and thus destroying the economic system because they will be affecting the money supply.\nIf you go with gold backed currency then the fairies can carry precious gems pretty easily (small ones, obviously)\nIf you go with government-backed currency then that solves the problem because the \"fairy government\" will back whatever tiny banknote is printed that is easy for the fairies to carry so the merchant will happily accept it because at the end of the week he can take the thimble full of fairy banknotes to the fairy government and get it exchanged for \"big people\" banknotes.\nIn Fantasy stories people often like to dispense with the simple fact that currency is mainly tied to governments. Governments are annoying things to have around since they introduce politics and politics complicates a simplistic idea of Good and Evil. So you have lines like from Lord of the Rings where <PERSON> compensates for stolen horses with \"12 silver pennies\" with zero mention of what government minted these pennies, where the silver came from, whether the pennies will be even of any value the moment they leave Bree, or if 12 silver pennies can buy the same number of horses anywhere else in Middle Earth (most likely, they can't) and are thus even a fair compensation at all.\nIn summary, the moment you said \"established currency system\" you are bringing in a whole set of things you are not considering that makes the problem you think exists, not exist at all. Any sort of established currency system will be only on ONE standard - gold or government - and either of those can easily handle this problem. You just need to pick which one it is.", "130" ], [ "Most of these answers are found in the questions mentioned as possible duplicates, but I think that the following discussion still has some value.\nFirst of all, trade requires different goods that can be exchanged. So instead of asking \"What good would they trade?\", the question should be \"What goods or services would they bring, and what goods or services would we give to them in exchange?\"\nThe simplest commodity for this situation is Energy. To quote the Hitchhikers Guide to the Galaxy, \"Space is big, really big...\" and to get from one place to another in a reasonable amount of time requires a lot of energy. If visitors were to come to our solar system with certain things we want (<PERSON> gives some good examples), they would come asking for energy. If they were able to load up with materials like hydrogen and uranium when they visited us, it would make a good stop, especially if they didn't have to mine those things themselves. The reason they would prefer to trade as opposed to mining themselves is that mining requires equipment, which means they have to bring that equipment, making space travel much more expensive.\nThere is also another advantage that Energy has; namely the fact that it is both exclusive and rivalrous. This means that it can be treated as private property and that when one person consumes it, others cannot.", "159" ], [ "These are almost essential to using them as trade. The issue with using information as a trading good is that it is neither of these. There is no way to control it as private property (without some higher governmental enforcement agency), and the fact that you had an idea does not keep me from having an identical idea on my own. Wikipedia has a good discussion of the topic, and you might be interested in doing some further research on the topic.\nAs a result it might not be that people trade knowledge per se, but instead basic resources (energy and materials to repair ships) and technology, or implementations of ideas. Maybe everyone knows that splitting water makes two hydrogen atoms and an oxygen, but if one species has figured out a way to split them with as little energy as possible, that is technology. That is something people might trade for.\nIn summary I would suggest that you study the following economic principles: Exclusivity, Rivalry, the economic concept of Utility, Opportunity Cost, and Comparative Advantage. These are the fundamental principles that modern international trade is based on, and intergalactic trade is just a much bigger version of the same set of problems and solutions.", "207" ], [ "Technology is highly dependent on the supply chain. A technology that can use local materials can be transplanted to a new area and be kept. For example, pottery spreads quickly because it uses local clays. Cell phones are highly dependent on the current supply chain and would not be usable on another world without importing huge amounts of supplies. Imports will be hugely expensive and prohibitive for nearly anyone. A museum might have a cell phone to show people what is done elsewhere.\nVictorian Britain had a lot of technology: steam engines, steel working, automated looms for weaving, coal mining, ship building, brick making, construction, beer brewing, Scotch distilling, barrel making, to name a few. Most of these were built upon centuries of saved up knowledge kept by specialized people.", "658" ], [ "Not every village had knowledge of how to do more than a few of these. The empire traded around the world so that a village didn't need to know how to make most stuff. They traded for the stuff they didn't know how to make.\nSo, if you were thinking of people taking technology and moving to another planet, the technology they can use would have to be stuff that can use whatever materials are locally available. Think of stone tools, pottery, and any plant materials that might be there. If you took only a village, you are taking at random a very select bit of technology knowledge.\nThe process of moving a group of people to a new location is by nature, a bottleneck on the transmission of knowledge. A lot of knowledge will be lost when the first generation of people die as most of what they know will not fit the new location and it will not be passed on to the next generation.\nAttempts to preserve the old ways will doom the village to a death as most of the old ways will not work well or will be extremely expensive.\nThe best you can hope for is to catch a rare general purpose genius who knows how to teach learning skills to the next generation. Instead of keeping the old technology, through trial and error, they will learn and develop the technology that works best in the new environment.", "998" ], [ "My answer is to apply monetary economics. I shall assume that technological or bio-technological solutions to increase the ability of the planet to dispose of significantly more waste heat than it does today are not feasible or desirable.\nSecondly, with all that MF power, lets get people making use of it to develop a spacefaring civilisation!\nSo my recommendation to the commission is roughly as follows:\n1. The (world) government shall establish a currency for which one unit can be redeemed against the rights to operate a MF that produces one unit of waste heat. This is similar to todays money which is redeemable against future consumption - now we explicitly tie money to entropy production. This currency replaces the current fiat system. Money based on energy usage has been quite widely discussed in the context of peak oil. This situation is essentially the same.\n2. The quantity of currency is fixed according to the capacity of the earth to dispose safely of the waste heat, so its different to todays money in which the economy is not energy constrained is is more constrained by supply and demand of finished goods.\n3. The government mandates that FI with their fantasticly secure technology that cannot be reverse engineered add a 'waste meter' to each MF that is loaded with the credits/money and will refuse to produce power when the credits run out.\n4.", "852" ], [ "These constraints do not apply for MFs used off-world, and this stimulates movement of power hungry manufacturing processes, and in time, residential establishments to move off world. Asteroids and comets are fetched to power the off world MFs. Since the off-world economy is not energy constrained, it uses its own forms of private currency similar to modern bank created money/credit. These currencies float against the terrestrial currency.\n5. Because the rights to production of waste heat on earth cannot increase, those trying to save money in terrestrial heat-currency may be subject to a negative interest rate or inflation in the terrestrial currency if he actual quantity of waste heat that can be safely disposed of by the planet declines due to government decree. When the global heat production limit is increased the terrestrial currency appreciates versus the off world ones, and vice versa when the terrestrial limit decreases.\n6. The 10% remaining on earth must spend their terrestrial currency on power production to maintain their standard of living, but also on importing finished goods from off world manufacturies (the data centres may also be off world). The off-worlders selling goods to earth get in return terrestrial currency that they can only redeem by either coming to earth an living for a while (many off world workers probably don't live off world all the time), and by importing stuff which cannot easily be manufactured in space - mainly stuff like quality food and drink, works of art, things like that. Ultimately to work, there has to be an equilibrium in which neither the off world nor terrestrial economies run a persistent trade surplus.", "130" ], [ "To be able to control earthquakes and volcanoes, we have to first understand them. We do not fully understand either. Actually, we know very little about both of them.\nOur current understanding of earthquakes involves several mechanisms. The most common are due to plate tectonics where either plates are moving apart, squishing into each other, or moving past each other. Unfortunately, there are earthquakes in places where none of those mechanisms fit (such as the New Madrid fault zone).\nOur understanding of most earthquakes is that they happen where some fault zone has stopped moving and the underlying plate is still moving. At some point, the movement of the underlying plate puts enough stress on the point that isn't moving to break the rock that is holding the fault stuck and the fault moves. It can move fast enough to actually melt the rock by friction.\nSo, for these earthquakes, you would need to invent a technology that can:\n1. find where the fault is building up stress\n2. Get down to that point (10-80 km below the surface)\n3.", "208" ], [ "Perform some action to start the fault moving again\nThere have been man caused earthquakes. Most of these have been caused by injecting waste water deep into a fracture zone at high pressure. We do not know how that fluid moved to the earthquake epicenter nor what the mechanism that triggered those earthquakes. All we know is that when we pumped that stuff down, more earthquakes happened nearby.\nAlso, we are still experiencing earthquakes on faults we didn't know were there.\nLikewise, with volcanoes, we would need to know how to predict them, how to measure the signals that something is happening, and then need to invent some technology that can harness that huge amount of energy release. It has been only in the last few decades that we have been able to do any prediction of volcano activity. Yet, with all the tools we have today, an Alaskan volcano gave less than 24 hours notice before erupting.\nTo simply harvest some of the energy of a volcano, think of how much heat is produced by one. Volcanoes are driven by mantle heat and the eruptions are partly due to water and CO2 changing from super pressured liquids into gas. Some estimates are that we could take a trillion watts of power from Yellowstone but the water requirements would be huge.\nFrankly, we would not want to cause eruptions, we would want to stop them. Pulling the heat out would slow them down significantly.", "912" ], [ "I suggest the following ingredients to make Feudalism more believable:\n* a very depopulated world\n* loss of agricultural productivity.\nLoss of agricultural productivity\nYou need loss of agricultural productivity and a tie-in to land for agricultural produce. More on that later.\nYou can have a loss of agricultural productivity by climate reasons. Or by loss of modern technologies, including any and all that make food supply ample. But low agricultural output and low productivity in general, even combined, do not require the foregoing of all post-industrial technologies and know-hows.\nFor example, say 90% of the remaining population on earth is required to produce sufficient food in aggregate. But a highly automated factory complex produce radios with few human input -- sure you always have upstream input but you can certainly have designs that suit simplified inputs. Said factory may be able to produce enough radios for 5% of the earth's population annually -- allowing some to always have new ones and the rest to only work with old radio sets that may become faulty in some way due to age. In this scenario, you could say a lot of technological advancement is included in the production of radio, so much so that very little input is enough to produce for the whole world. Yet overall productivity of the world is low because food is required and food is being a bottleneck for greater economical development.\nLoss of agricultural productivity can be important for Feudalism. Feudalism was a land-based social order where\n1) workers were tied to the same parcels of land all-year-long\n2) nobles had the authority and ability to tax production from (larger) land parcels\n3) a hierarchy existed to combine tax over large geographical areas and thus support things such as a military that can provide stability and order and some luxury items that helped people feel that the authority was deserved and proper.\nIf people can move around freely and still be a part of a productive process, then they won't be willing to stay under some abstract contract that bind them to some designated noble -- however relatively un-educated they may be.\nSo for the sake of Feudalism, you should tie 90%+ of earth's remaining population to daily working over the same pieces of land.\nNote that low variability in agricultural productivity is also needed. ie. You shouldn't have a single place that is highly productive and nowhere else that can produce food. If the only place that can produce starch based food is in the UN headquarter building in a city named New York. You can have whatever social order that makes sense at UN.", "222" ], [ "Outside of it, people are not tied with land anymore.\nThat said, a generally unproductive world but a few pockets of productivity -- even within agriculture -- can make for interesting dynamics. Like 0 everywhere vs 100 at one place wouldn't work. 1 vs 2 on the other hand could be interesting.\nA depopulated world\nA depopulated world does a number of things in Feudalism's favor, including:\n* difficulty to maintain law and order over vast areas (and the consummate incentive to banditry)\n* difficulty to maintain education\n* even more difficulty with aggregate output that feeds into everything above\n* the same sequence of events could have destroyed the social/national institutions in our real world in the same stroke\nThe implications are self-evident. Without the large population the modern earth has and supports, the historical benefits Feudalism was supposed to provide are not easily replaced via alternatives. They included social cohesion and stability of life. The key is to take away alternatives.\nWhat loss of agricultural productivity achieves is that people are unable to move around and be productive other than being peasants of their specific pieces of land. Depopulation takes away plausible alternatives by not permitting individuals with free time. For 90%+ of population, you work your field for 8 hours a day or your starve. Otherwise, when people have free time, they will try to do things that break the current order. Say there is no difference between a republic where a government imposes tax and a monarchy where nobles do in term's of people's daily experience. If you give people free time, given the communication technology, they may still rebel against a Feudal system and put a republic in place out of preference. That's why free time should also be difficult to come by.\nPerhaps you can also introduce other factors that accentuates the lack of free time. Perhaps, to make agriculture work in that post-apocalyptic world, farming is very complex -- you need recurring efforts to deal with certain side-effects from radiation, maybe add some new micro-organism that people have to work against -- while being unproductive relative to our real world.\nAnd there you go, I think with some details, Feudalism can become realistic enough.\nYet at the same time, you are not restricted in having modern transportation, modern communications, modern entertainment, etc.", "222" ], [ "The answer depends almost entirely on the exact nature of the political and economic system.\n1. Who controls the robots? Do people have equal shares of robotic resources? To what level can they perform business and advance their resources?\n2. Who checks violation of the law? How does one pay for mistakes? The robots?\n3. Who makes laws? Can laws be changed? By the international authority? Or are the permanent? Who keeps them permanent?\n4. Who forms this international survey you talk of? Robots? People who are considered moral (but could be deceptive)? Elected representatives?\n5. Is there a motive to even have currency?\nIt is nearly impossible to create a perfectly equal society. If you are hypothetically making one, please specify so.\nEdit\nI am answering keeping the OP's reply in mind....\nAs long as people can advance their resources legally (in other words, perform business), capitalism is inevitable. It will be quite similar to our world economically, where the smartest people will eventually earn the most amount of money, along with a few lucky people.", "207" ], [ "Terrorism will be a major problem, assuming that nuclear weapons have been thoroughly researched by then.\nYou mentioned that those who developed robots are responsible for them. I assume that it is legal for individuals to develop robots. Each country will use robots for the army (if we still require manpower in futuristic military).\nCorruption will still exist. People with money will get away more lightly.\nThey have the same possible judgement. If I am to take that literally, every human has the same opinion on every issue, eliminating the need for such a body. Further, it is fundamentally against human nature, so the humans become kind-of robots themselves.\nIf difference of opinion is still possible though, it depends on who is in power. Democracy will work as well in the future as it does now, some countries will have really good systems, some will not. If the international system is really good, they will soon let out total control to the robots (as long as the First Law of the robots, of not harming humans and not having an individualistic greed, cannot be broken). This will completely revolutionise the society (in which case, ignore the above answer).", "207" ] ]

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[ [ "What does be back in 10 minutes mean??\nWhat does be back in 10 minutes mean for your customers?\nWhat does Be back in 10 minutes mean?.\nit means to knock on the door as loud as possible.\nYell out hello through the window if it’s open.\nCall the office as you stare into an empty chair thinking someone will magically appear if you do so. You know because you are outside walking back to the office. Staring at them as they are dumbfounded confused.\nBoth call the office while knocking on the door.\nOr the trifecta, call the office while knocking on the door/window and yelling hello.\nBoy do we love it!\nIt’s the best when you are directly staring at the sign!", "1015" ], [ "<PERSON> who asked if the ice was cold came back…\nHe came back for a business meeting. He got there first. (1st on a 6 top) he ordered for everyone. We have big portions so ordering family style is normal in a group. But he did not even wait for 3 minutes before he ordered enough for like 10 people. I even said that’s a lot of food, wanna just start with having apps on the table? Nope, <PERSON> wanted to ORDER. OK sir, I gotchu.\nBusiness lunch went great. Everyone was happy, want some of the dudes were happy to take food home to their kids. Lovely.\nBut. I.", "406" ], [ "Shit. You. Not. It fucking happened again…but even more awkward.\nDude next to <PERSON>: Can I get a refill please? Pepsi no ice. Thanks.\nFucking <PERSON>: hey can I get more water?\nMe: absolutely, be right back!\nFucking <PERSON>: wait he said no ice. I don’t think I want ice. Is your ice cold??????\nMe: (prepared this time) the coldest we got. (Feeling good about that quip)\nFucking <PERSON>: that doesn’t actually answer my question.\nMe: angry server stare/laugh and then walk away\nFUCKING <PERSON>: I guess no ice then.\nThis mans face will haunt my goddamn dreams FOREVER. What do you mean when you ask is the ice cold?????? I’m so fucking confused. What do you want from me!?!?\nHe is either working on another level of dad jokes or the biggest idiot I’ve ever met. And it drives me absolutely insane that I’ll never be able to know which it is.", "406" ], [ "Discounted vs Discontinued\nI used to work at a pet store (not anymore thank god) and I randomly remembered a ridiculous interaction that repeated what more times than it should. If an item in the store was not going to be manufactured anymore, or wouldn’t be sold there the store would mark the last of their stock of that item “Discontinued” so customers would know it wouldn’t come back.\nMultiple times, customers would come back to yell at me because their product was not discounted on the receipt.\nI would say to them “that product is not discounted.", "866" ], [ "“\nthey would say “YES IT IS!! I SAW it on that sign!!!”\nI would say “can you show me the sign?”\nshows me the sign that says “discontinued”\ni would then relish greatly saying “ma’am/sir, that sign says “discontinued” that isn’t the same thing as “discounted””\nespecially after they got an attitude with me about me being stupid and “forgetting their discount”. Never failed to humble them. 😂😂😂", "423" ], [ "Why buy that many of you're just gonna leave it?\n3 people bought a total of 200 of the cheapest bags my store sells. I even had one of my supervisors look for an unopened box as I had not a lot under the register.\nAfter a lot of scanning later (their total bill came close to £300), they paid, loaded the cart up and left. They were completely rude the entire interaction and they didn't thank me once. Even left me a lot of items they didn't want.\nThe funniest thing is, after wanting the 200 bags, they left the box of them behind.", "866" ], [ "Like how can you leave a heavy box of bags?\nThey even went to load their car up and came back in for other items (they paid at another register). Not once did they come to my register for their bags.... So they wasted money on something they left behind. Karma at it's finest", "866" ], [ "Is your ice cold?\nI’ve been in the industry for over 15 years. I’ve heard some shit. But a few months ago I was waiting on a couple, probably in their early 40’s, the wife asked for an iced tea without ice. The husband asked for a water, and then said “I’m not sure if I want ice. Is your ice cold?” We had been having a good interaction so I thought he was making a dad joke and kind of chuckled (so did his wife).", "640" ], [ "But no. He just stared at me and said “why are you laughing”. I kinda stumbled a bit but couldn’t think of a response and finally said “I’m confused by your question sir”. Thankfully his wonderful wife just side eyed him and said “are you fucking serious? Are you ok?” Which lead to this exchange…\nHusband:”yes, I want to know if their ice is cold?!”\nWife: “ <PERSON> what are you doing?”\nHusband to me: “Answer my question please”\nMe: “umm, it’s frozen water, so yea…it’s cold??”\n<PERSON>: “then I don’t want ice”\nMe: “gotcha”\nAs I walk away I hear his wife ask if he’s having a stroke. Which he responds with “don’t belittle me” and then asking for my manager because he needed clarification on whether ice is cold or closer to room temperature.\nI’m still thinking about it 4 months later.", "201" ], [ "You Are So Hard To Find, We've Been Looking All Over For You!!!\nI love it when people come to the store and the first thing uttered is an outburst \" you are so hard to find, we've been looking all over for you, no one knows where you are\" and then rage about parking which is a topic I honestly don't give a fuck about. All this and they have actually arrived on time.\nMy regular reply is: \"We are right here.", "866" ], [ "In this room. It's always hard to find somewhere the first time\". Sometimes I go to stage 2: \" the whole front of the building is plasti-wrapped with our name and logo and there is a 4 meter (15') sign out the front\".\nWhat they are really saying is how unorganized they are and that they don't know how to access information services, check Google information in advance.", "1015" ], [ "Server blunder days\nI was 21 years old gal (looked like I was a teen) and was fairly new to the place and at a restaurant job. It was the first time being the only server/ host scheduled since we were so slow. I could multi-task (act as host/server/food runner/busser and side work). But I struggled to handle small talk and food/drinks at the same time\nI go to refill coffee, this lady in her 50s/60s asked “are you the only one here? How come?” As I’m processing how to answer, I overfill the mug and coffee pours out onto my hand.", "828" ], [ "I have a high tolerance for heat and I was distracted so I didn’t feel hot coffee. None spilled on her thank goodness but now she’s freaking out. She’s pulling napkins and icing my hand. I was calm and assured her I was ok. I felt bad that she was genuinely asking a question and that happened\nDoes anyone have blunders from their early restaurant/food days?", "201" ], [ "Other-Office Team Members\nIn my department, about two thirds of my team live overseas in the Philippines (they even all teamed up to try to teach me Tagalog on slow nights when they heard I liked languages... how cool is that?!)\nWe're pretty close and when it's not super busy, we play question games to get to know each other via Teams (whats your go-to karaoke song? if you could have any pet, knowing it would behave itself...", "1015" ], [ "mythical, extinct or other, what would you have? A genie gave you one wish, but you have to use it on yourself. What do you wish for?.... stuff like that)\nDo you guys have a not-in-building team that you work closely with as well? What is your relationship like? Where are they located?", "630" ] ]

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[ [ "How can an Existing Centralized Finance System Defeat a Crypto-currency?\nPremise\n(-clears throat-)\nI'm imagining a world where financial systems are considerably centralized and the wealthy top few percent hold much sway, so to speak. In this world, it's not inconceivable for money to influence politics or for the special governmental / financial relationships to exhibit rent-seeking behavior.\nThis kind of institution frustrated some groups of people and some experimenting was carried out. A crypto-currency was developed (at least in part) to decentralize the finance system by taking the central banks out of the equation and allowing users to interact with each other comparatively freely. A limit of the number of the crypto-currency was set, to create scarcity and not allow for rent-seeking behavior or infinite money printing. While this crypto-currency had a modest adoption rate in terms of its user base, it's net-worth has already eclipsed some of the major investment-banks and other inner sanctum constituents of the financial elite. However the value of this crypto-currency is very volatile, ranging wildly, sometimes even from month to month. Still, some think this crypto-currency represents the future of finance, and to an extent the world as a whole. As this world has followed a trajectory of increasing decentralization with the advents of newer technologies.", "205" ], [ "In the past this world had kings and emperors and religious elite, now democratic institutions are gaining momentum (or that's the rumor anyway).\nThe problem is, the powers that be in the existing financial system would surely not relinquish their grip on the financial system lightly. Maybe they leverage their political clout to ban it outright, or they launch a smear campaign to legitimize it. Or perhaps they could acquire enough stake in it so that they could embrace it. Whatever the existing financial elite do, it would have to benefit them both economically and strategically/politically. The financial system elite are mindful of how fine a line must be walked to avoid creating a \"martyr\" out of the currency. That is to say, can it be banned outright or would that create its own set of problems (over regulation, control state, suspicion, ect)? That is the crux of it.\nTo narrow the scope a bit, let's say diplomacy has failed and the two financial systems are at odds with each other. Even if the existing finance elite hold a large stake of the crypto-currency, the intrinsic scarcity of the crypto-currency will make it too challenging for the financial system elite to conduct rent-seeking that they look rather fondly on.\nQuesion\nWhat is the best (for the finance system) strategy for the financial system decision makers to defeat the afore-described crypto-currency?\nClarifications\n* Setting: Near future\n* Success metric: stop the rising adoption of the crypto-currency and keep the it on the fringe or completely non-existant\n* Acquiring the crypto-currency is allowed (e.g. acquire and freeze), but it must not be used\n* Must imagine you are on the panel of the finance system (what's best for the finance system, might not be best for mankind as a whole, ect)\n* Timeframe: The faster the better\n* Ethics: little to no concern (don't pull any punches)\n* Doomsday scenarios: Ideally, the world would be left in-tact, nuclear war would be avoided and so forth, but if it really, really, truly calls for a doomsday solution, so be it, just explain why", "207" ], [ "Why would an immortal make good on his loan?\nPremise\nMy world that has undergone a transformative breakthrough in biology and genetics. It's not just the ultra-rich who have it; rather, everyone is immortal. However, this world's understanding of economics is roughly that of Earth's. The public finance tools available to this world is also the same as Earth's. This creates a rather perplexing finance-related challenge for the society.\nOn Earth, it's not unheard of for countries to go into debt and take a long time to pay it off. Strictly theoretically speaking, countries don't ever have to pay off 100% of their debt. There are a few reasons for this, but one of the most chief of which is: countries do not have a finite lifespan.\n[ EDIT: As per the suggestions in the answers/comments, I might reconsider my word choice. Instead of saying countries have no finite lifespan, let's just say they have no predetermined lifespan, or even better a lifespan with no upper ceiling ]\nCreditor countries take this into consideration. Yet, the same does not hold true for Earthlings; most Earthlings are presumed to have a finite life span and cannot incur debt indefinitely without some form of punishment along the way.\nSimilarly, in my world, the immortals also do not have a finite lifespan; creditors get peace of mind that said immortal has all of eternity to pay up. This line of logic became the official policy in my world -- there is no explicit loan payment date.\nAssume the immortals go into debt for the following financial incentives:\n* Driving growth of investments: it would be risky, but ultimately more profitable to borrow money into debt in order to get higher returns from investments (real estate, stock market, ect)\n* Inflation: assuming inflation increases over time; it's always going to be cheaper to pay off debt at a later date.\nGiven there are sufficient financial incentives for immortals to incur debt, and creditors allot an infinite amount of time to pay back the loan, everyone stands to make profit.", "590" ], [ "It seems too good to be true... In such a scenario where money can be borrowed and spent indefinitely, the immortals could drive up inflation infinitely. The world doesn't want hyper inflation. Yet the world is also not budging on their ethos:\nEthos: \"you have eternity to pay back the loan.\"\nQuestion\nIf there is no explicit due date, the immortals could abuse the world's ethos/policy as articulated above. Essentially, the question then becomes why bother paying the loan back at all? The immortals could say to their creditors: \"I'll pay you back later.\" for all eternity.\nAssumptions:\n* the world ideally wants a functioning/healthy financial system (hyper-inflation is undesirable for this world)\n* the percentage of the population in debt is anywhere from 80% to 99.99%\n* over-population and other non-finance related notions are out of scope for this question\nImmortality Details\n* limb regrowth, starvation, disease, trauma\nSo as not to invalidate any existing answers, I will leave this as optional. To keep the logic used thus far as consistent as possible, we can assume these afflictions have minimal effects on the individuals. Assume immortals are impervious to all afflictions. Side Note: I originally considered a more humble form of immortality by which they have a full recovery in 48 hours or less, but I thought that could have a loop-hole where creditors could cut off a limb at regular intervals. Again, this isn't mandatory for the answer, but if the answerers feel so inclined to include a note about this, that's fine. However, I have included these details mostly in the interest of elevating the general discussion.\nSuccess Metric: incentivize as many immortals as possible to make good on their loans without imposing a due date\n<PERSON>: \"In the long run, we're all dead.\"\nImmortal: \"Wrong.\"", "590" ], [ "How can a malign government suppress life-saving technology?\nPremise\nThis is meant to be a dark corollary of the cliche \"demographics are destiny.\" The premise is a hegemonic-like state with persistent drawdowns in fiscal income. Meanwhile unfunded liabilities, to a large extent includes social security, are growing too fast for this state. They've already invoked all the financial voodoo they could in terms of tenor of debt issuance and letting inflation run higher (to pay back less to bondholders in real terms). But it was not to be enough. Faced with a run on their currency (which the state needs to acquire goods and commodities it needs but can't produce), the decision was made to start pulling levers on human lifespans -- indirectly and quietly via suppressing things like cures to cancer.\nIn today's world of interconnected and peer-reviewed medical research, the above scenario seems a bit unrealistic. This is the crux of my dilemma. I'd imagine that facilities with the manpower and equipment to develop major life-saving technologies would be from prominent biotech companies. Much of these would have public floats and be subject to shareholder interests, board of directors and transparent financial reporting.", "824" ], [ "Granted there are still information asymmetries and insider trading opportunities, but let's assume the market has grown savvy to blatant market abuse.\nBut simply put, these are companies with very public profiles and a very interconnected web of medical professionals. I see the interconnectedness of all these scientists (nodes) as well as a more transparent form of corporate governance as major obstacles for the government to prevent something like 'the cure for cancer' from making it to market.\nA comically stylized script might read:\nDeep state man: Here's the deal. That trial was not a success, it was a failure. And I was never here.\nResearch director: Whatever you say. But I have 300 researchers under me that will need convincing. Some might be willing to play ball, but others have a moral conscience.\nCEO: This miracle drug is virtually a mandate for us. We have decades long correspondence with our shareholders and bondholders and now is the big moment. If the trial is a failure again, we can stall for time but in a few years we're going to be in big trouble.\nQuestion\nHow can a malign government to suppress a life-saving technology altogether or at least reduce as many points of failure in this plan as possible?", "824" ], [ "A monad is just a monoid in the category of endofunctors, what's the enlightenment?\nPardon the word play. I'm a little confused about the implication of the claim and hence the question.\nBackground: I ventured into Category Theory to understand the theoretical underpinnings of various categorical constructs and their relevance to functional programming (FP). It seems (to me) that one of the \"crowning gems\" at the intersection of Cat and FP is this statement:\nA monad is just a monoid in the category of endofunctors\nWhat is the big deal about this observation and what are its programmatic/design implications? Sources like sigfpe and many texts on FP seem to imply the mindblowingness of this concept but perhaps I'm unable to see the subtlety that's being alluded to.\nHere's how I understand it:\nKnowing something is a monoid allows us to extrapolate the fact that we can work within a map-reduce setting where the associativity of the operations allows us to split/combine the computation in arbitrary order i.e., (a1+a2)+a3 == a1+(a2+a3). It can also allow one to distribute this across machines and achieve high parallelization.", "154" ], [ "(Thus, I could mentally go from a theoretical construct -> computer science understanding -> practical problem solving.)\nFor me it was obvious (as a result of studying Cat) to see that monads have a monoidal structure in the category of endofunctors. However, what is the implication one can draw from this and what is its programmatic/design/engineering impact when we're coding with such a mental model?\nHere's my interpretation:\n* Theoretical Implication: All computable problems at their heart are monoidal in a sense.\n* Is this correct? If so, I can understand the enlightenment. It's a different perspective on understanding the notion/structure of computable problems that wouldn't be obvious if coming from only a <PERSON>/<PERSON> model of computation and I can be at peace.\n* Is there more to it?\n* Practical Implication: Is it simply to provide a case for the do-notation style of programming? That is, if things are monoidal we can better appreciate the existence of the do/for constructs in Haskell/Scala. Is that it? Even if we didn't know about the monoidal underpinnings, we needn't invoke the monoidalness to make this claim since bind >>= and flatMap constructs are defined to be associative. So what gives? Or is it more to do with the foldability of monadic constructs and that is the indirect enlightenment that is being alluded to?\nQuestion(s): What am I missing here? Is it simply the recognition of the fact that monads are generalized monoids and that they can be combined in any order similar to map-reduce operations like monoids? How does knowing about the monoidal property help improve the code/design in any way? What's a good example of before/after to show this difference (before knowing about monads/monoidality and after)?", "603" ], [ "In my world one of the branches of magic is Sight; foresight, farsight and hindsight.\nThe challenges of hindsight should not any different than of foresight. While the timeline is fixed, there is significantly more information to parse, and requires intensive focus and energy to filter out the important from the mundane. Hindsight would not be like watching a movie or a video, but comes in patches (fragments of compressed and extended time) and requires the intelligence of the seer to identify what they are seeing. Imagine that time is like glass that is more substantial the closer it is to the present, but disintegrates as time goes by, with spikes surrounding strong emotional/spiritual periods (such as a murder, but not a theft by someone in control of their emotions).\nAlso figure out the magic ability that would block sight. While Lords are hiring Seers, criminals are hiring the \"smokers\" to obscure things from the magic sight (even to the point of kidnapping and human trafficking). There might be a separate magic type to obscure distance (\"farsmoker\") and require a \"timesmoker\" to obscure hindsight and/or foresight. Naturally the practice of \"smoking\" would be outlawed. (Personally there should be just as many smokers as there are seers to balance the magic...", "917" ], [ "children of seers could be smokers or vice versa).\nOne possibility is that a Foreseer committing a crime could probably obscure their actions from a Hindseer (countering the future actions). On the other hand, it would be possible for a Hindseer to influence the timeline so that it is also obscured to other Hindseers by the very act of viewing the past. So in a way, the Foresight and Hindsight Seers are their own \"time smokers\" because a scene can usually only read a few times before static and other corruptive influences start to degrade the vision (fragments shatter). Basically all that is required to corrupt the scene is a Foreseer (before the crime) or <PERSON> (after the crime) to read the scene one or more times. Obviously, the strength and power of the seer can affect the outcome with a weaker seer corrupting the scene and a strong user still able to pluck what they need. But it would be obvious to any <PERSON> that the timeline was corrupted. (NOTE: it would be the time+space with a limited sphere of influence that would be corrupted/static, and no obliteration of everything that happened in the past in that space.)\nBTW, it might be also interesting to have the polar of farsight... tinysight/microsight, which may also have a different method of solving crimes.\nWhile your original question was how to make the Hindsight less powerful so that crime was not wiped out, the premise of a crime novel based on this magic would be very interesting.", "45" ], [ "Social implication of economics based on brain processing power\nI'm working on a future cyberpunk setting in which I would like to explore posthumanism as a main theme. Among some of the ideas I have I want to use the very well explored \"decking\" trope.\nThe idea is that at some point in time humanity managed to create a crude brain-computer interface, that allowed not only access to silicone machines, but also running programs using brain's terrifying processing power. Hence, Technological Singularity followed, with wealth represented by physical production facilities becoming obsolete, as with the excess processing power brute-forcing trade and political forecasts became feasible. Finally, technology demands caught up with the supply and humanity's most relevant stock is now carefully traded processing power. Countless people have been contracted to trade in the power of their brains in exchange for remuneration and it just so happened, that average level of intelligence turned out to be the easiest and most efficient to utilise.\nNow, most people work by plugging in to the data processing cloud for a set amount of time. The contracts vary, with a significant amount of people enjoying games etc. while being plugged in and trading in a set percentage of their brain activity, some having only passive reception of data with minimal amount of interactivity left to the brains posessor. The most extreme (and well paid) employees would lay comatose while nearly 100% of their brains are being devoted to stock trading or running AIs. Of course, majority of the population would unplug for at least a couple hours every day to enjoy real life. That also assumes that entertainment and similar services moved on to the new medium, Neuromancer style.\nThat would leave only the misfits living mostly in the physical world - the geniuses, the morons, the weird and strange minds that are too different to be a mass resource.", "205" ], [ "They would too be able to plug in, but extracting processing power would be too inefficient for them to provide a reliable source of income.\nWhat would be the social and economical implications of such a world? Keeping in mind that <PERSON> literally sells his brain time to someone else and his mediocrity and predictability is prized and promoted, what sort of man would he be? What sort of values would he hold, what would he believe in, what would he want in his life? How would he spend his time off and how would he spend his time? I'm looking for a kind of stereotypical Everyman definition, the same way we recognise the idea of \"mid-range corporate employee\" or \"middle-class big city dweller\".\nIn response to comments: I imagined the transition to processing power as an after effect of general transition towards virtual life. Of course main expenditures would still be rent, utilities, food etc. However, a person might forgo all earthly things and basically occupy a coffin rigged with life support gear, while living his life in virtual environment. Now to create such an immersive environment power of brains of others would need to be utilised, effectively balancing the processing power budget. The excess would be utilised towards human advancement - even if that just means more sophisticated virtual goods (experiences). Generally, it would seem, that at any given point participants in this \"cloud brain\" structure would be divided into suppliers and consumers, with one creating processing power for the others. Apart from human consumption I would imagine there are AIs who require immense number of brains, but enabling technological singularity and - being sentient - having an attitude towards human suppliers. Of course, different variations are possible, such as Matrix scenario where AIs would harvest power by oppression or a more caring one, where proliferation of brains is actually achieved by AIs genuinely forging a better future for humanity.\nI would imagine in a world that derives wealth from processing power, other resources such as food, construction materials and energy would be harvested automatically - using AIs and self-sustaining plants. Work for the incompatible geniuses would be most likely centred on frontier areas - where network is not sufficient to sustain automatic AI or it is not feasible - such as space exploration, colonisation. I would imagine that such a civilisation would be probably halfway to becoming a Type II, according to <PERSON> scale.", "693" ], [ "How to keep a country rigorous when not at war?\nI'm trying to create a world that has a strong military and good citizenship even in times of peace. I'm kind of stuck at the moment, but I have done some research already, so here is a brief case study I have been putting together. I used evidence from a world called: \"Earth.\"\nCase Study: Earth\nA famous Earthling named <PERSON> once said:\nWar should be the only study of a prince. He should consider peace only as a breathing-time, which gives him leisure to contrive, and furnishes as ability to execute, military plans.\n<PERSON> puts it so eloquently that it sounds self-evident. However, <PERSON>, a political columnist of Time Magazine, submits that even a country as economically developed and militarily powerful as the US actually falls short of the mark:\nSince WWII, yes we have had some problems, but [America] has not had any existential wars in which all of our young people have to go out and fight. In the interim, I think that we have lost a lot of the habits of citizenship. In contrast to the men and women in the military, we do not feel as if we are part of something that is larger than ourselves. We have re-tribalized our society.\nWhat is good citizenship?\nWhat exactly constitutes \"good citizenship\" is subjective to a degree. Whether you agree or not, to keep the scope of the question within reason, consider \"good citizenship\" & \"rigorousness\" here to mean:\n* sense of basic unity. Putting the good of the government over the good of the tribe (to use <PERSON>'s framework).", "714" ], [ "Thus creating a \"rigorous\" state, in which citizens weight heavily how their actions impact the government, because of a presumed sense of basic unity.\nOptional Musings\nNotably, in the post-Vietnam era, it has become fashionable to be skeptic of the government. Hollywood often portrays government or deep-state villains. There is an anti-establishment vibe that pervades everywhere from off-shore banking on wall street to the Malthusian moral hazards of exploiting welfare.\nQuestion\nIf America fails to keep society from being fragmented and tribalized, as per the earlier definition of \"good citizenship\", how can a fictional state that is similar to America learn from any potential mistakes and do better? Or would any such state be doomed to fail to stay \"rigorous\" in times of peace? Why or why not?\nFurther Clarifications and Assumptions:\n* You do not need to encompass all the definitions of good citizenship in your answer. That is to say you can make it as broad or as narrow as you feel comfortable with. Just state which one(s) you choose and how it factors in to your answer. For example, maybe your solution focuses on political literacy and voter turn out. Or maybe you approach things from the military/veteran care angle.\n* For the sake of simplicity, all solutions should adopt the organic view of government -- the individual only has significance as part of the community. Mechanistic (where government is for the benefit of the people) views I feel will distract answers from the heart of my question.\n* I do not wish to create a state of brain-washed people who all drink the koolaid. Rather, I want a healthy degree of skepticism that does not take away from the good of the country.\n* Not that we could every truly have such knowledge, but just for robustness, assume the government is relatively benevolent. Maybe there are inefficiencies or cases of corruption, but the government is not trying to murder its own people or something extreme like that.", "207" ], [ "War in a dystopian setting\nIn a world where there is ever-declining population due to a phenomenon that has no satisfactory explanation, what could cause war or large-scale armed confrontations between countries or sections of the society?\nAssumptions:\n* No births have happened for a while. No new pregnancies are happening.\n* The cause for this population decline is unknown and there is no apparent cure/solution.\n* The decline is unstoppable; humanity will soon be extinct.\nGiven that humans realize they will soon be gone for good, what could create a situation where human lives are intentionally harmed?\nEDIT:\nI noticed that I need to word my question better, so I'll add here what I posted in a comment.\nMost of the answers so far assume the worst of humanity; stuff like \"Might as well do anything I want, since I'll die one day\". The thing is, that is true for all humans even now. Why would the possibility of there being zero humans a few decades from now foment conflict today?\nFor additional clarity, consider the following:\n* The realization that there are more humans dying that those being born sinks in slowly.", "934" ], [ "This isn't a T-virus/asteroid/alien invasion scenario, where humanity is given a few weeks till extinction.\n* For most people, news about economic indicators like labor costs or population decline isn't worth a lot of attention. So it's conceivable they carry on with their lives (for what I assume will be quite a while) until this starts affecting them personally. By then, governments & society are likely to grasp the fact that every human life is \"precious\", much like tigers or pandas today.\nSo, I guess my question is, when governments are actively engaged in (however futile) efforts directed towards conservation of human life, what would cause war or any armed conflict between humans?\nEDIT 2:\nA lot of excellent answers. I'm going to have to pick out elements from each answer and cook up a cascading series of events that form the basis for some bitter resentment between the principal actors and a spark that starts the fire.\nIf only I could accept more than one answer...", "934" ] ]

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[ [ "Sea Navies are there to help monitor for rebel spaceship emergency landings, but also for non-rebel spaceships requiring a Splashdown landing\nOne thing about other countries on the planet that would likely cause an issue is landmass - if there's enough landspace for interplanetary travel via spaceships, which country houses which landing pads would be a contentious issue - since that could be farmland, or residential building lands, or mountains, or...\nThing is, other planets could be contacting via spaceships, and the landing pads sort of likely need to exist for communication, and supplies, or the transport of people between planets.\nWhich means you'll have a lot of details around immigration and exports/imports in the country, and you'll want to cut down on rebel smuggling attempts and such. If an unauthorized spaceship attempts entry, they could choose not to even land at your landing ports, and just land in any ocean, or on a deserted island, and stay hidden.", "199" ], [ "Not great for a world government. But since you'll have to check the oceans and seas anyways, that seems like a great place to put your official landing ports for official, authorized travel.\nSo, what you'll want to do is have your sea navy in charge of air traffic control essentially for interplanetary travel - when you attempt to land, the following happens:\n1.) You contact the local sea navy by planetary comms from outside atmosphere asking for an entry point, with maybe some guidance on which continent or city you want to depart at;\n2.) The sea navy gives you coordinates to land at sea near the departure point, and send their landing pad out to that coordinate.\n3.) You then enter the atmosphere, aiming for a targeted landing at that location.\n4.) You hopefully* land on the landing pad at sea.\n5.) You're transported by a ferry accompanied by the local navy ships and end up at your destination.\n6.) Your ship is docked such that, for takeoff, you can take a landing pad out to see and launch off of that once you're ready to leave.\n*This keeps the country from having to worry about mishaps in landing mistakes - instead of setting fire to a landing pad on land, and having to worry about their forests as much, if you do cause a fire explosion with a mistaken landing, they can just dunk the landing pad or your ship into the water to reduce the effects. Ideally, this doesn't happen, but if it does, that can be contained safely.\nAnyone attempting to land without these steps is probably a rebel, so you encounter them with the navy if they land in the sea - which is likely their easiest target anyways, because there's likely to be a lot more water that is safe to land at than land with cities, or farmland, or notorious parks.", "500" ], [ "When things go fine, they're essentially working at a button factory. The situations where they aren't are when things go bad.\nIn general, space traffic controllers would do a few things:\n1. Confirm someone's intending to land at the station, and verify peaceful intent on approach.\n2. Figure out which docking bay is free for that given ship to use, and indicate to the ship where it is, and provide a note to other air traffic controllers that said dock is being used.\n3. Confirm that ships leaving a docking area have clearance to leave/aren't on lockdown, and that the area is clear for them to leave.\n4. Keep track of when ships leave a dock and that dock opens up for another ship, and pass that information to other air traffic controllers so that they know that dock is now freed up.\n5. Confirm that the ships know where they're going, and that they are, in fact, going there.", "500" ], [ "And that they can, in fact, get there.\n5.) is where things become complicated; because things can go wrong on any of the other steps. Because most of the time, when you give a person a dock, they can get to that dock, or request a closer one. But emergencies, you run into issues of where they can dock in an emergency.\nIf, say, a stray micrometeorite destroys their engines, you might end up in a situation where they need to land, but specifically, can't land back at the dock they just left a few minutes ago because of their current momentum. If your lucky, you can find them another dock in short time - if you're unlucky, you get to prepare emergency recovery services for when they are \"Going to be in the Hudson\".\nWhich sort of gets to the core of why you wouldn't dedicate an A.I. to take on the initial steps of this - the Hudson River is not a runway, landing strip, or airplane docking port; your A.I. that tries to handle this is going to have an issue about this and be \"particular about it and make it a runway/dock.\".\nThese are rather stressful situations presumably, which is why it's great that those situations are usually rare, and the job is usually a button factory workplace job. You go into work everyday hoping that's the type of day it is; but you never know when it's going to be a \"Hudson\" day, so the docking station prepares for the case where it is, in fact, one of those days.", "500" ], [ "Frame Challenge\nIt's not a ship that would find a planet, it's an observatory.\nKeep Watching the Skies\nRight now, we've found 4 341 planets outside our solar system, and we've only barely sent one space ship outside of same. Even with many space ships, people wouldn't be sending ships to go find planets. Even in Star Trek, stellar cartography is mostly handled by enormous telescopes.\nSo that's what your planet would be hiding from. An enormous space telescope, probably built a long way from the star of its solar system, gradually cataloguing all the stars in the night sky. Watching for the dips in intensity that indicate a planet, and the spectral lines indicating what its atmosphere is made of. We can do that now with space and ground-based telescopes. Any civilization that has starships is going to have much, much better telescopes that are constantly on the lookout for where their next scouting team is going to be sent.\nSo then that's the challenge. The pirates happen to find a planet in an as-yet unmapped part of space...", "199" ], [ "but the cartographers aren't sitting still. So the question is - how good are the telescopes, and how many of them are there? There are approximately 200 billion stars in the Milky Way. Assuming a Cartographic Observatory can process ten a day, it would take fifty million years to work its way through them all, and 25 million to find a particular planet at random. But if it can work through ten thousand a day, and if there are a thousand such installations... the pirates' secret planet's days are numbered.\nSide Note: Space is Big\nIt would make sense to only fly through charted territories, so random asteroids and pirates are not as much of a problem, right?\nPirates may be a problem. Asteroids are not. Our solar system's asteroid belt is pretty dense as far as such things go in space. The average distance between any two objects in that belt is approximate 966 thousand kilometres.\nThere are not (indeed, cannot be) asteroid belts as dense as those pictured in Star Wars, because such a belt would aggregate into a planetoid or planet, unless it was a very, very recent phenomenon (Alderaan, for example).\nSo if you choose a direction at random in the sky, and fly your rocket in that direction for twenty lightyears, the odds that you hit anything of note once you leave the mess in Earth's orbit behind are astronomically (haha) low.\nIf you want a reason for people to take particular routes, it's best to have it associated with how you handle FTL - because asteroids, nebulae, and other space-borne objects are not a reasonable threat.", "921" ], [ "Many other people have pointed out the information paradox of black holes, which, based on our understanding of black holes today says that you could not input information into black holes and obtain meaningful results from any type of output (Hawking radiation) in this case.\nBut, we're talking about a black hole that sits inside a planet, so I would wager that whoever built this probably has a better understanding of black holes than we do. If you want to stay within the realms of our current understanding, I would put forward two possible scenarios (both from 30,000 ft so as not to get bogged down in the muck and mire of all the unknowns surrounding black holes):\nDecoding Hawking Radiation\nThe black hole was created (and permanently exists within) a larger planet aka. a closed system, unlike any black hole we know of. The circumstances surrounding the construction and implementation of this theoretical information-storing black hole are known. It is possible that under these circumstances all variables can be accounted for - all matter and energy that has ever entered the black hole is known - and an algorithm was developed based on this in order to obtain meaningful information.\nThis depends on the nature of your weapon though. If it is a physical device, you won't be able to put it into and out of a black hole like it's a box.", "43" ], [ "If it's some sort of cyber-weapon consisting of data alone, it's doable.\nBlack Hole is the Weapon\nIf you don't want to interpret the radiation that is coming from the black hole, perhaps the black hole itself is the weapon. When ready for use, the black hole could be expelled from the planet on a trajectory that sends it to the target destination - wiping out everything along the way - and eventually destroying the planet or solar system it is targeting. In the meantime, the planet is at work gathering resources to construct another black hole.\nGoing to destroy the weapon would be a suicide mission, as disabling the planet would cause it to implode and anything in the vicinity would be destroyed as well.\nThis is also the ultimate dead-hand weapon. Containing a black hole would require substantial energy and matter. Assuming you could contain a continuously growing black hole indefinitely, it would require an indefinite amount of resources - depleting the surrounding space in turn. If the weapon is never used, it sits until the heat-death of the universe or close to it, where it will be used regardless, ensuring that it wipes out", "99" ], [ "The Undead don't know when to hold 'em, don't know when to fold 'em, don't know when to walk way, and don't know when to run.\nHuman soldiers fleeing a battlefield is usually not a good idea, but there are situations where it might be useful for your human soldiers to flee a battlefield and let a commander know when a situation has changed dramatically not in their favor.\nTake, for example, sending some troops across a mountain range, over a plains biome, and across a bridge to try and attack a force on the opposite side (i.e. a city territory, a set military barracks, etc.).\nThe other side might setup a few troops on their side of the bridge as scouts, and when the Undead start to cross it, allow them to, in part - and then destroy the bridge.\nThe Undead on the other side of the bridge might then try to walk across or use undead bodies as a bridge to cross over, but they could be susceptible to Greek fire in the river between the bridge, or just being pelted with arrows as they attempt to do that.\nWhile a set of scouts try to also take on the undead that have successfully crossed the bridge, or just let the much smaller force try to take on the barracks or city. If they allow 10 Undead at a time to try and attack the barracks, it doesn't matter if you send 100 or 10000 Undead soldiers - 10 Undead at a time is presumably manageable for the opposing army, barring them automatically resurrecting on the site as they die.\nIf this was a human force of soldiers in the same situation, the soldiers crossing the bridge before it was destroyed may respond to the destroyed bridge by surrendering, or fleeing to the mountains, while the side that hasn't yet crossed the bridge may provide covering fire for them or begin fleeing themselves, perhaps back across the path to the commander to report on what happened. They may also setup camp outside of the river area while sending a smaller scouting party back to ask for reinforcements or bridge building capabilities, or additional orders. If they encountered the Greek fire and had no existing knowledge of it before, they would also want to relay that back.\nSimilarly, if they encountered Greek fire while on ships, humans would understand that not only are their lives important to get back, but so are the ships that were built - especially if it was followed up by catapults throwing rocks at them to try and sink them. Some orders are given with a bad understanding of the situation.\nAdditionally, you can give a human force - especially a human commander - enough information about their task that they might catch on to information that indicates that the information higher command has is incorrect, or a possible trap, and update them as necessary.", "164" ], [ "For example, if you send them to take on a large group of the enemy army force to keep them away from a castle you're planning to siege, and they show up and find only 90 soldiers holding up the outpost instead of the 900 you thought were going to be there, a human commander might fight the 90 soldiers quickly, but also send a messenger back to alert their high commanders that their information is presumably out of date; there's a discrepancy in the force they were told to attack and the force that was there. Useful information if you have a mole in your team providing false information.\nFinally, humans will likely retreat if they feel that the enemy army is starting to encircle them, or attempt to force them into a worse situation. The Undead may still want to fight the enemy force, because that was the order they were given, and they may not have gone to war with the enemy force if they weren't compelled to anyways.\nFurthermore, the Undead have no inclination to prevent the enemy forces from killing them and resurrecting them against you.\nIf your Undead fail to successfully defeat the enemy and instead get themselves routed, then now the enemy has a full group of soldiers they can resurrect and send back against you. As a bonus, they're already equipped with all the equipment they really need.\nYou did equip the Undead with armor and weapons, right?\nYour human soldiers, upon realizing they may be in a losing fight, and that they may be resurrected as Undead, and may deliberately either flee to make it harder for them to be resurrected, or get themselves stuck under crushing buildings or rocks, or deliberately try and break and destroy their lances, swords, and bows, such that they can't be used against their allies. At the minimum, they can start denting their weapons on purpose. Not ideal, but they can try and avoid giving an advantage to the enemy - maybe they cut off their sword arm just before dying, or their legs, or both legs and arms in a final act of defiance.", "164" ], [ "Nazi sasquatch vampires (And their thralls) guarding the perimeter keep people out.\nAdmittedly, this is a large border, but this'll become a bit easier once they start resurrecting the nuclear dead, or intercepting foreign aid groups.\nForeign aid groups might actually make it easier to uphold the charade - \"Oh, things are totally fine here, we're doing our best - they're even recovering!\" or \"Maybe send some more crew to the same port - we found plenty more needing help here.\". Letting the outside world think they're helping while not actually successfully helping.\nWorst case scenario - the bluff fails, and everyone knows their aid attempts fail spectacularly due to the vampires keeping them from succeeding, and if you succeed, well then the vampires can keep up the masquerade and effectively blindside everyone when they find out what actually is happening.\nOther, non-nuclear conflicts break out in the rest of the world\nThe U.S. has an often discussed and criticized policy of being able to fund their army to be able to run a two theatre war. Even at the largest funding it had there, they're looking at 2 major conflicts and one limited conflict.\nBut the map you're presenting isn't that large a portion of the world; give the U.S. three major conflicts that aren't Europe.", "164" ], [ "You've still got all of Asia, all of Africa, and all of South America to choose from, let alone a possible Civil War breakout making them have an additional local conflict.\nEven if Europe is a strong contender for foreign aid, you're indicating that civilization is basically dead in Europe - perhaps at a glance, the U.S. looks at that, goes \"Well, that's horrible; we have to intervene elsewhere and make sure nowhere else ends up like that.\". Basically containment of conflicts to keep them from having to aid another region is what's keeping them from aiding Europe at the moment. Especially if they're aware of the whole Nazi Sasquatch Vampire situation.\nFor bonus points - have the non-nuclear conflicts break out nearby nuclear countries. That can give you a potential read on the global news as Europe is hoping those conflicts don't go the way theirs did.", "454" ], [ "You can't hide the engines\nIf we're assuming hard science no-magic-warp engines and ships that go places in years, not millenia, then the most visible part of any ship is going to be it's exhaust. In most natural planetary environments, there is nothing that could be confused with it. Some answers here are arguing that you might make a ship so \"quiet\" that can be confused with an asteroid - but that can be done only while not maneuvering at all.\nEven our current technology allows us to make an exhaustive list of any ships firing their engines in our closest star systems - I mean, there aren't any; but if someone used any engine capable of moving a sizeable ship (as per the requirement of some people inside, not a tiny probe; plus a capability for maneuver not the current practice of a single burn and airbrake because we don't have enough fuel to stop) in story-meaningful time - say, no more than a few months for interplanetary distances or less than a century for interstellar distances - then we already would know it.\nIf you're seen, we know that you're not natural\nWe can't do it yet, but there should be no issues for a spacefaring civilization to have a detailed list of every asteroid of significant size (say, ship-size) in their planetary systems, in the same manner that we currently track every baseball-sized piece of junk in earth orbit. Yes, there are many of them, that's why we have computers. We don't frequently get any new asteroids, and when we do, we can observe the collision that made it.", "199" ], [ "If a ship that's otherwise indistinguishable from an asteroid arrived in some soft-science way, say, from hyperspace - then we'd still could get an immediate and automated warning from passive sensors that hey, we have a new asteroid that wasn't there yesterday.\nOnce you are detected, you stay detected forever\nLet's assume that some pirate successfully robs a ship, gets some loot, starts running away and has the quietest most hidden ship possible. Well, we still know where exactly it is, and and rather accurately where it will be in next month or next year. The only thing that a perfectly stealthy ship can do is float in a straight line, and the moment it wants to adjust it's course, then once again everyone will know where exactly it is and where it's going to now.\nThis also means that \"You never know when space pirates are going to strike\" is not really true - every space station would have an exhaustive list of every ship that is currently on route \"nearby\" (for very, very large values of \"nearby\" - passive detection of engines would work at longer ranges than ships with those engines will fly in a lifetime) as well as their exact routes, since you don't need their cooperation to obtain that, you just need to look. If you don't want to fly past anyone, then you don't. If someone fires up their engines to intercept you, then you notice that well in advance, and everyone else does as well, and is able to track the other ship to wherever it goes to.", "500" ], [ "There are several reasons that WW2 Naval / Aerial style combat isn't likely in a sci-fi space setting. There are a number of per-requisites that are necessary or likely before space travel is commonplace that would cause combat to be long periods of waiting followed by burst of action too fast for humans to comprehend.\nSpace combat would take place at ranges and speeds that make human interaction almost irrelevant, and humans become little more than payload.\nAdditionally, with the amount of kinetic energy projectiles traveling at orbital (much less near-relativistic) velocities armor is mostly meaningless and a larger ship just means a larger target.\nSo let's break down each of the things that make space combat happen this fast, and ways to ignore or invalidate them.\nSensors / Stealth - One key to any space combat is that, in space, there's nowhere to hide. It's a big empty place that making it hard for a camouflaged ship to hide itself and ambush another ship or fleet of ships.\nWhile a ship could possibly mask itself behind the other side of a planet, as soon as it comes into view it'll be quickly detected by the heat it gives off relative to the emptiness of space. Complicating matters even more is the potential for surveillance drones that scout ahead and around possible terrain - something we'll need to address later.\nPretty much right off the bat you'll need to find some reason to make ships invisible to one another until they are in close proximity. Some sort of countermeasures like ECM that makes radar / lidar / other active sensors ineffective, and some sort of 'cloaking device' (which could be as simple as coolant that lowers the temperature of ships skin to the cold of space) that makes passive IR sensors ineffective.\nOne additional thing is you can crib from submarine warfare where using active sensors gives away your own position. Of course, there's again little reason that drones / scout ship pickets couldn't do the sensing / jamming rather than the bulk of the combat fleet.\nDistance Space is vast. It could be days, weeks, months, even years after detection where two combat fleets would jockey for position in interplanetary combat. Cutting this down would require vastly improved propulsion systems - some sort of jump / warp / relativistic drive to cover large distances quickly. This becomes less of an issue if you're talking about combat around a single planet, but it still takes days for the most powerful rockets even get from the earth to the moon.\nOf course, if you're using vastly more powerful drives, you need a way to slow combat back down when the fleets close. I'd suggest jump drives aren't accurate enough (possibly imprecise, sensors blinded while jumping, etc) that forces fleets to jump near each other but regroup rather than jump directly into combat using slower drives.\nSpeed - The other side of the distance coin.\nStuff in space moves fast.", "898" ], [ "Super, almost incomprehensibly fast. A spacecraft in earth's orbit is moving an order of magnitude faster than a bullet fired by a powerful gun, making it nearly impossible for a human to identify and react to inbound missiles. Energy weapons move even faster.\nOnce you've used your jump drives to close into 'combat' range, you are still going to have fleets closing on one another at thousands of miles an hour. You aren't going to have dogfights, you're going to have bullets blasting past bullets.\nThe only thing possibly fast enough to react is going to be machines, basically missiles crashing into missiles. There needs to be some incentive to put people in these missiles rather than making them computer controlled fire-and-forget weapons.\nComputers - Computers can do everything people can do faster than people can do it. Why bother with people who take up space, need life support, and are little use in combat? There absolutely needs to be a reason that powerful computers don't work in combat, otherwise everything is robots fighting robots. Human reaction speeds need to be meaningful.\nArmor - Armor is meaningless when you're talking about the speeds above. A kinetic projectile fired impacting at the closing velocities above will have enough energy to devastate a capital ship. Even more importantly, that capital ship won't have any time or opportunity to maneuver and avoid that projectile.\nGotta have some sort of shield to absorb those projectiles and the high power energy of lasers.\nShields - There needs to be some sort of shielding to dissipate energy weapons. Of course, there can be consequences of this like only large ships can power shields, and powering shields either takes so much power or it renders the shielded ship impossible to maneuver.\nSo anyway, to sum this up:\nShips can't detect each other at great distance due to jamming / not wanting to reveal their positions. Stealth systems multiply this factor.", "898" ] ]

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[ [ "Chapter 26, Knights and squires, Moby Dick\nI am not a native English speaker. I am struggling with the last few paragraphs of chapter 26 of moby dick. I tried using a dictionary and even translating to my native language but the dots don't seem to connect. I am not able to get the intuitive feeling of these paragraphs. I tried reading it multiple times, but I don't feel satisfied.\nI don't want to skip any line of a book that plays such an important role in English Literature.\nBut were the coming narrative to reveal in any instance, the complete abasement of poor <PERSON>’s fortitude, scarce might I have the heart to write it; for it is a thing most sorrowful, nay shocking, to expose the fall of valour in the soul. Men may seem detestable as joint stock-companies and nations; knaves, fools, and murderers there may be; men may have mean and meagre faces; but man, in the ideal, is so noble and so sparkling, such a grand and glowing creature, that over any ignominious blemish in him all his fellows should run to throw their costliest robes.", "624" ], [ "That immaculate manliness we feel within ourselves, so far within us, that it remains intact though all the outer character seem gone; bleeds with keenest anguish at the undraped spectacle of a valor-ruined man. Nor can piety itself, at such a shameful sight, completely stifle her upbraidings against the permitting stars. But this august dignity I treat of, is not the dignity of kings and robes, but that abounding dignity which has no robed investiture. Thou shalt see it shining in the arm that wields a pick or drives a spike; that democratic dignity which, on all hands, radiates without end from God; Himself! The great God absolute! The centre and circumference of all democracy! His omnipresence, our divine equality! If, then, to meanest mariners, and renegades and castaways, I shall hereafter ascribe high qualities, though dark; weave round them tragic graces; if even the most mournful, perchance the most abased, among them all, shall at times lift himself to the exalted mounts; if I shall touch that workman’s arm with some ethereal light; if I shall spread a rainbow over his disastrous set of sun; then against all mortal critics bear me out in it, thou Just Spirit of Equality, which hast spread one royal mantle of humanity over all my kind! Bear me out in it, thou great democratic God! who didst not refuse to the swart convict, <PERSON>, the pale, poetic pearl; Thou who didst clothe with doubly hammered leaves of finest gold, the stumped and paupered arm of old <PERSON>; Thou who didst pick up <PERSON> from the pebbles; who didst hurl him upon a war-horse; who didst thunder him higher than a throne! Thou who, in all Thy mighty, earthly marchings, ever cullest Thy selectest champions from the kingly commons; bear me out in it, O <PERSON>!\nBefore this paragraph, the narrator was talking about the qualities of <PERSON>, and it was making sense. But then, he diverged. He went from <PERSON> to democratic God(what does that mean?) very abruptly.", "381" ], [ "What \"kind\" of writing is The Fixation of Belief essay by <PERSON>?\nI happened by this essay a couple of years ago, now. I've been trying to find things written in a similar style since. However, I'm not terribly familiar with writing analysis, terminology, categorizing, et cetera. So I haven't really been able to to describe the attributes that I like about the essay well enough to find similar writings.\nTo clarify, clearly this is non-fiction. That's not what I'm asking. Also, it's clear to me that the subject of the essay is primarily epistemology. What I mean by style is more like cadence, I guess, seemingly unusual use of many comas for expressing nested thoughts, tone, maybe, and how he talks to the reader. I'm also not entirely sure if it would be considered academic writing. Is it?\nFull text: Fixation of Belief\nPartial text:\nFew persons care to study logic, because everybody conceives himself to be proficient enough in the art of reasoning already. But I observe that this satisfaction is limited to one's own ratiocination, and does not extend to that of other men.\nWe come to the full possession of our power of drawing inferences, the last of all our faculties; for it is not so much a natural gift as a long and difficult art. The history of its practice would make a grand subject for a book.", "460" ], [ "The medieval schoolman, following the Romans, made logic the earliest of a boy's studies after grammar, as being very easy. So it was as they understood it. Its fundamental principle, according to them, was, that all knowledge rests either on authority or reason; but that whatever is deduced by reason depends ultimately on a premiss derived from authority. Accordingly, as soon as a boy was perfect in the syllogistic procedure, his intellectual kit of tools was held to be complete.\nTo <PERSON>, that remarkable mind who in the middle of the thirteenth century was almost a scientific man, the schoolmen's conception of reasoning appeared only an obstacle to truth. He saw that experience alone teaches anything -- a proposition which to us seems easy to understand, because a distinct conception of experience has been handed down to us from former generations; which to him likewise seemed perfectly clear, because its difficulties had not yet unfolded themselves. Of all kinds of experience, the best, he thought, was interior illumination, which teaches many things about Nature which the external senses could never discover, such as the transubstantiation of bread.\nFour centuries later, the more celebrated <PERSON>, in the first book of his Novum Organum, gave his clear account of experience as something which must be open to verification and reexamination. But, superior as Lord <PERSON>'s conception is to earlier notions, a modern reader who is not in awe of his grandiloquence is chiefly struck by the inadequacy of his view of scientific procedure. That we have only to make some crude experiments, to draw up briefs of the results in certain blank forms, to go through these by rule, checking off everything disproved and setting down the alternatives, and that thus in a few years physical science would be finished up -- what an idea! \"He wrote on science like a Lord Chancellor,\" indeed, as <PERSON>, a genuine man of science said.\nThe early scientists, <PERSON>, <PERSON>, <PERSON>, <PERSON>, <PERSON>, and <PERSON>, had methods more like those of their modern brethren. <PERSON> undertook to draw a curve through the places of Mars; and to state the times occupied by the planet in describing the different parts of that curve; but perhaps his greatest service to science was in impressing on men's minds that this was the thing to be done if they wished to improve astronomy; that they were not to content themselves with inquiring whether one system of epicycles was better than another but that they were to sit down to the figures and find out what the curve, in truth, was. He accomplished this by his incomparable energy and courage, blundering along in the most inconceivable way (to us), from one irrational hypothesis to another, until, after trying twenty-two of these, he fell, by the mere exhaustion of his invention, upon the orbit which a mind well furnished with the weapons of modern logic would have tried almost at the outset.\nIn the same way, every work of science great enough to be well remembered for a few generations affords some exemplification of the defective state of the art of reasoning of the time when it was written; and each chief step in science has been a lesson in logic. It was so when <PERSON> and his contemporaries took up the study of Chemistry. The old chemist's maxim had been, \"Lege, lege, lege, labora, ora, et relege.", "417" ], [ "What's meant by \"the illusion of the chapel ended\" in The Just Men of Cordova?\nIn chapter 17 of The Just Men of Cordova (1917) by <PERSON>, the author is describing a captured man who had been led to a building:\nThe sight he saw was a remarkable one. He was in a chapel; he saw the stained-glass windows, but in place of the altar there was a low platform which ran along one end of the building. It was draped with black and set with three desks. It reminded him of nothing so much as a judge's desk, save that the hangings were of purple, the desks of black oak, and the carpet that covered the dais of the same sombre hue.\nThree men sat at the desks. They were masked, and a diamond pin in the cravat of one glittered in the light of the huge electrolier which hung from the vaulted roof. <PERSON> had a weakness for jewels.\nThe remaining member of the Four was to the right of the prisoners.\nWith the stained-glass windows, the raftered roof, and the solemn character of the architecture, the illusion of the chapel ended.", "624" ], [ "There was no other furniture on the floor; it was tiled and bare of chair or pew.\n<PERSON> took all this in quickly. He noted a door behind the three, through which they came and apparently made their exit. He could see no means of escape save by the way he had come.\nThe central figure of the three at the desk spoke in a voice which was harsh and stern and uncompromising. \"<PERSON>,\" he said solemnly, \"what of <PERSON>?\"\n<PERSON> shrugged his shoulders and looked round as though weary of a question which he found it impossible to answer.\n\"What of <PERSON>, of <PERSON>, of a dozen men who have stood in your way and have died?\" asked the voice.\nStill <PERSON> was silent. His eye took in the situation. Behind him were two doors, and he observed that the key was in the lock. He could see that he was in an old Norman chapel which private enterprise had restored for a purpose.\nIt's already said at first the he was in a chapel, so does the author meant here that <PERSON> firstly guessed that he was in a chapel, then he became totally sure of that?", "573" ], [ "2 or 3 Things I Know About Her\n[...] Maybe an object is what serves as a link between subjects, allowing us to live in society, to be together. But since social relations are always ambiguous, since my thoughts divide as much as unite, and my words unite by what they express and isolate by what they omit, since a wide gulf separates my subjective certainty of myself from the objective truth others have of me, since I constantly end up guilty, even though I feel innocent, since every event changes my daily life, since I always fail to communicate, to understand, to love and be loved, and every failure deepens my solitude, since... Since... since I cannot escape the objectivity crushing me nor the subjectivity expelling me, since I cannot rise to a state of being nor collapse into nothingness... I have to listen, more than ever I have to look around me at the world, my fellow creature, my brother.\nThe world alone. Today, when revolutions are impossible and bloody wars loom, when capitalism is unsure of its rights and the working class is in retreat, when the lightning progress of science makes future centuries hauntingly present, when the future is more present than the present, when distant galaxies are on my doorstep.", "283" ], [ "My fellow creature, my brother.\nWhere do we start? But start what? God created heaven and earth, sure, but that's too easy. We should put it better: Say that the limits of language are the world's limits, that the limits of my language are my world's limits, and that when I speak, I limit the world, I finish it. And one inevitable and mysterious day, death will come and abolish these limits, and there will be no questions nor answers. It will all be a blur. But if by chance things come into focus again, it may only be with the advent of conscience. Everything will follow from there.\nA primeira tentativa de ensaio de Godard e o começo da sua segunda modernidade. Se a linguagem é a casa onde o homem habita, <PERSON> lar.", "660" ], [ "I think the assumption is that <PERSON>'s songs are an expression of something more complicated than power.\n<PERSON> has this to say on <PERSON> in letter 144:\n<PERSON> is not an important person – to the narrative. I suppose he has some importance as a ‘comment’. I mean, I do not really write like that: he is just an invention, and he represents something that I feel important, though I would not be prepared to analyze the feeling precisely. I would not, however, have left him in, if he did not have some kind of function. I might put it this way. The story is cast in terms of a good side, and a bad side, beauty against ruthless ugliness, tyranny against kingship, moderated freedom with consent against compulsion that has long lost any object save mere power, and so on; but both sides in some degree, conservative or destructive, want a measure of control.", "417" ], [ "But if you have, as it were taken ‘a vow of poverty’, renounced control, and take your delight in things for themselves without reference to yourself, watching, observing, and to some extent knowing, then the question of the rights and wrongs of power and control might become utterly meaningless to you, and the means of power quite valueless. It is a natural pacifist view, which arises in the mind when there is a war.\nAs an embodiment of a pacifist position, he can't be said to have \"power\" at all, and neither can his songs.\nPolitical power, martial power, magical power, the power of the rings, are all inherently \"corrupt\" in that their aim is to alter the tide of affairs, to change the world as <PERSON> made it, in order to serve the aims of those who wield power (even if they intend to do something good with it). The ring, as the physical manifestation of the will to power, represents this inherent corruption.\n<PERSON>'s songs, like those of <PERSON>, are linked to the creation of the world, to the perfect condition of things before they are corrupted by greed, or pride, or the other failings of beings. <PERSON>'s \"power\" if he has it, is to be of a world untouched by these failings and not to want to exercise power at all, but rather to be imbued with what remains of a world untouched by it. <PERSON> is so untouched by power, so immune to its influence, that even the ring has no effect on him. His essential essence is effective in Middle Earth (against corrupt wights and tree spirits, etc.) because it is part of the perfect state of the world close to its creation, something that is, in itself, effective. This state is something shared by his land, and his songs are essentially conservative - they reassert the original condition of the world by repeating the process by which <PERSON> created it.", "72" ], [ "What does \"hard pushed in argument\" mean in this context?\nIn \"In the Midst of Alarms\" (1894) by <PERSON>, a blacksmith, <PERSON>, did an embarrassing trick to break the conceit of his New Yorker client in front of the crowd in his smithy, but he failed\n<PERSON> saw there was no triumph over him among his crowd, for they all evidently felt as much involved in the failure of <PERSON>’s trick as he did himself; but he was sure that in future some man, hard pushed in argument, would fling the New Yorker at him. In the crisis he showed the instinct of a <PERSON>.\n“Well, boys,” he cried, “fun’s fun, but I’ve got to work. I have to earn my living, anyhow.”\n<PERSON> enjoyed his victory; they wouldn’t try “getting at” him again, he said to himself.\n<PERSON> strode to the forge and took out the bar of white-hot iron. He gave a scarcely perceptible nod to <PERSON>, who, ever ready with tobacco juice, spat with great directness on the top of the anvil. <PERSON> placed the hot iron on the spot, and quickly smote it a stalwart blow with the heavy hammer. The result was appalling. An instantaneous spreading fan of apparently molten iron lit up the place as if it were a flash of lightning. There was a crash like the bursting of a cannon. The shop was filled for a moment with a shower of brilliant sparks, that flew like meteors to every corner of the place.", "624" ], [ "Everyone was prepared for the explosion except <PERSON>. He sprang back with a cry, tripped, and, without having time to get the use of his hands to ease his fall, tumbled and rolled to the horses’ heels. The animals, frightened by the report, stamped around; and <PERSON> had to hustle on his hands and knees to safer quarters, exhibiting more celerity than dignity. The blacksmith never smiled, but everyone else roared. The reputation of the country was safe. <PERSON> doubled himself up in his boisterous mirth.\n“There’s no one like the old man!” he shouted. “Oh, lordy! lordy! He’s all wool, and a yard wide.”\n<PERSON> picked himself up and dusted himself off, laughing with the rest of them.\n“If I ever knew that trick before, I had forgotten it. That’s one on me, as this youth in spasms said a moment ago. <PERSON>, shake! I’ll treat the crowd, if there’s a place handy.”\n1- I found that \"hard pushed\" means \"face a great difficulty in doing something\", but I can't get the whole meaning of this phrase in this context.\n2- What did he exactly mean by \"I’ll treat the crowd, if there’s a place handy\".\nThanks in advance.", "417" ], [ "Lady <PERSON> received <PERSON>'s letter about witches' prophesy and became ambitious, immoral and a tempter. She did say\nUnsex me here\nBut this has nothing to do with her gender, a lot of times it has happened in history that women have played deceitfully, immorally and cruelly for example you can take <PERSON>, wife of <PERSON> and daughter of <PERSON>'s General <PERSON>, was cruel and ambitious too.\nThe only way for Lady <PERSON> to gain power is through <PERSON> using her rhetoric.\nThat was true, she rewired the brain of <PERSON> (which was already fighting with the ambitious Devil) and made him to do what he feared. But not only she used rhetoric but also showed masculinity by taking the blooded daggers from <PERSON> and placing it there. But again this rhetoric persuasion should not be related with gender, as we find in <PERSON>; <PERSON> persuaded <PERSON> with murderous thoughts.\nDo you think that the tragedy of Macbeth is the consequence of <PERSON> is being too sensitive to masculinity? What does Masculinity mean for <PERSON>?\n<PERSON> was not less masculine, in Act 1 Scene 2 he is depicted as:\nfor brave <PERSON> – well he deserves that name\nand he is considered violent too:\nHe unseamed him from the nave to th’chops\nbut it is unjust to think of his pure conscience as a sensitive masculine character, he after murdering the king <PERSON> expresses his inner voice as:\nI am afraid to think what I have done; Look on't again I dare not.\nSo, considering the above saying of <PERSON> and comparing it with \"He unseamed him from the nave to th’chops\" it doesn't seem that <PERSON> was afraid of blood, he was afraid of himself and Higher Self, even at his death his last words were\n.", "247" ], [ ". .my soul is clog’d with blood—\nI cannot rise! I dare not ask for mercy—\nIt is too late, he drags me down; I sink,\nI sink, — my soul is lost forever! — Oh! — Oh!\nHe thinks and worries about his soul, his feeling of guilt was overtaking him. The hallucination of <PERSON> was just another portrayal of how deeply <PERSON> was aware of his murderous sin.\nThere are some of the lines in Macbeth that do demonstrate gender hierarchy, <PERSON> said to Lady <PERSON>\nBring forth men-children only;\nFor thy undaunted mettle should compose nothing but males\nand Witches warned <PERSON>\n<PERSON>! be bloody, bold and resolute;\nlaugh to scorn the power of man;\nfor none of woman born shall harm <PERSON>.\nTo re-quote your question\nWhat does Masculinity mean for <PERSON>?\n<PERSON> was valor, and respected by whole men of <PERSON>. <PERSON> knew what sins always bring to the sinners at last, his extreme feeling of guilt and consequential hallucination was because of the transparency of his heart.", "773" ], [ "How powerful <PERSON> is in the beginning of \"An Outcast of the Islands\"?\nI'm first time reading a novel of <PERSON>, I was inspired and revered him since I saw Apocalypse Now. But as <PERSON><PERSON> is regarded as a very skillful, detailful and prolific writer so I must admit that my knowledge is a little low to fully understand him, therefore confusion arises and I have to come here for clearing up a doubt.\nIn the first chapter of An Outcast of the Islands, <PERSON> (the main character of the novel) is described as very powerful and somewhat as sophomaniac. To quote from the book:\n[...] he kept them(Da Souza tribe) singing his praises in the midst of their laziness, of their dirt, of their immense and hopeless squalor: he was greatly delighted.\nThey lived (Da Souza tribe) now by the grace of his will. This was power. <PERSON> loved it.\nAnd he depicted him as intelligent by\n<PERSON> knew all about himself. On the day when, with many misgivings, he ran away from a Dutch East-Indiaman in Samarang roads, he had commenced that study of himself, of his own ways, of his own abilities, of those fate-compelling qualities of which led him toward that lucrative position which he now filled.\nSo, these remarks suggest that <PERSON> was very powerful and law himself, and more importantly he himself made him. But a little later in the same chapter, when <PERSON> is going home the book writes\nLeaning against one of the brick pillars, Mr. <PERSON>, the cashier of Hudig & Co., smoked the last cheroot of the evening. Amongst the shadows of the trimmed bushes Mrs.", "381" ], [ "<PERSON> crunched slowly, with measured steps, the gravel of the circular path before the house. \"There's <PERSON> going home on foot- and drunk I fancy,\" said Mr. <PERSON> over his shoulder. \"I saw him jump and wave his hat\".\nIt's been mentioned in the first chapter that <PERSON> is a clerk for Hudig & co., and at the same time his prowess is talked about. The confusion is that in my society and as far as I have seen, clerks are the ones who give receipts for something, to be a bit direct: they are employees of comparingly low power. So, given that <PERSON> is the head of the whole Da Souza tribe and everyone lives by his grace, how come Mr. <PERSON> makes such remarks on him? And how could he be just a clerk of a company when he got such powers (whole army of that tribe) which hardly anyone in that company have?\nKindly explain me the situation of <PERSON> as can be deduced from the first and second chapter of An Outacst of the Islands.\nUPDATE: In the third chapter it is written that\nHe had married her [<PERSON>] to please <PERSON>, and the greatness of his sacrifice ought to have made her happy without any further exertion on his part.\nI’m lost even more here as to who <PERSON> was and how marrying <PERSON> would have pleased him? <PERSON> & co. can be imagined as a company which transports its products over the whole Europe and these Asian countries like Malaysia, Indonesia. I’m unable to understand how Da Souza tribe is related to Hudig & co.", "950" ] ]

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[ [ "The Batman\nnow, now. wow! this one was a really solid film! i wasn't expecting to like it the way i did since i'm not really into the dc universe, i'm more of a marvel guy, but i actually enjoyed it very much! i'm not even really fond of marvel movies too, i don't really expect too much on superhero movies actually, but this one was something else. it had a lot of strengths, the score and the acting, for example. that score! insanely good. that acting! are y'all crazy? every single person ate! the pacing was pretty good too. it was gripping. i wanted to get into the batman universe more.", "583" ], [ "the portrayal of batman in this was really interesting and amazing. the movie was long but it didn't feel long. i really thought i would just thirst over zoë & robert but i was fully invested. this is how i like my superhero movies, i suppose. it can be the best one out there, even. not cheesy, not bait-y? it had this story to tell and it told that pretty well. its biggest and maybe the only flaw was that one “not all cops” kind of moment, gives you the ticklish feelings, but i guess we can interpret that in different ways. deserves a rewatch.", "583" ], [ "tick, tick...<PERSON>!\nfinally watched rent at least the film, for this one. of course tick, tick... BOOM! is on my watchlist but it was not at all what i expected. after hearing his songs and a perspective into his life through this film, <PERSON> seems like a lovely and creative soul, which the dreamers can easily sympathise with.", "657" ], [ "♡ going back to the film, this was so great and executed well and i wish i can say <PERSON> works do not reach me as well as they do but now evidently more, it does. anyways i could not wait to bring him up, oh my god... <PERSON>! what a man how is he so phenomenal and why have i not been following his career more? i did not even know he could sing, im soso impressed by his performance and he truly made this film. again what a man.", "410" ], [ "Avengers: Endgame\ni saw this film 24 hours ago and i still feel emotionally and physically drained.\ni don't know how im gonna process after seeing THAT, but i'm ecstatic to see what the MCU has planned for the future films. this was amazing in every way possible, ending in a very satisfying note that the previous mcu films failed to make me feel. it felt like it was really the conclusion for some heroes that was beloved by many for the past decade and paving the way for the new ones to start a fresh. cinematic history is being made right before our eyes.", "457" ], [ "i'm glad to be a small part of it, as a fan who cares about these characters probably waaay too much. i'm beyond grateful for this wonderful franchise. thank you <PERSON>, <PERSON>, <PERSON>, <PERSON>, <PERSON>, <PERSON>, to the producers, directors, and to everyone who helped on creating the MCU.\nand of course to <PERSON>, the man, the myth, the legend. The Marvel Cinematic Universe wouldn't be the same without you.", "19" ], [ "Black Mirror: USS Callister\ndear <PERSON>,\ni am writing an apology to you because, no matter how much your physique or age changes, no matter how nice you can act and how you are in real life, i will forever dislike you for the sole reason of <PERSON>. im sorry thats just how it is and it is not your fault.\nthe only black mirror yet where i want to actually share my thoughts but i dont like doing that so i’ll just say yeah so good it could’ve just been a feature length film.", "1009" ], [ "pairs so well with white christmas which i loved. but also how the hell did they get <PERSON> at the end as a toxic gamer without the inclusion of a ‘yeah bitch’. still a bomb ass cameo but cmon <PERSON> you cowards", "585" ], [ "Edge of Tomorrow\n“come find me when you wake up.”\n<PERSON> is truly the king of action. i mean this with no disregard to any older hollywood legends, but he has just got it down to a t. the comedic time, the stunts, the pure fun of this film and the suspense.", "217" ], [ "holy fuck. i’m an absolute sucker for action and this is up there with one of my new favourite action films. i watched this when i was like 13/14 but i didn’t remember it well and im so glad i gave it another shot.", "462" ], [ "Iron Man\n“you are a man who has everything and nothing”\nrevisiting this film after several years was a spur of the moment decision. i was craving a film with action but also with a lot of emotios + stakes. so i traveled back in time to when the mcu actually gave a shit about the work they were putting out into cinemas.\niron man is truly the best & most fantastic introduction film to an entire franchise universe. the tone in the beginning was one of serious accords, keeping you on your toes with just the right amount of dark humor to balance things out.\ni mourn the loss of phase 1 mcu films.", "457" ], [ "were they perfect ? absolutely not but they had heart, soul and actually made you think, should i give a fuck about this billionaire playboy with daddy issues? it presented us with the reality that life is never so black and white. it’s the grey areas that hold the most weight.\niron man depicts <PERSON> for exactly who he is. they present him to us in a way that you’ve formed any opinion only being 5 minutes into the film. but when you keep watching, you see a man who is conflicted, struggling with his beliefs that his father instilled in him and questioning if it’s something he truly believes. by the end of the film you get your answer in <PERSON>’s way reminding you that he’s still him but with a new outlook on life and tech.", "80" ], [ "The Five Devils\nundeniably an interesting movie with a fascinating premise; i can’t help but feel something was missing, though. it didn’t grab me like i’d hoped it would. i also cannot exactly look past how this was very much a movie made by white french people that didn’t quite know how to center its black characters, particularly the black queer woman who is supposed to be so formative to the story.", "236" ], [ "however!! i am definitely not the individual to be delving into that and there are surely better criticisms of that on this app—i have no interest in sounding like a white knight of film criticisms. my criticisms don’t take away from the fact that it was really strong performances all around (<PERSON> is always a gem, i love how much acting she does with her face) and some really beautiful interior and exterior shots. the mood of this whole movie was pretty well crafted, too.", "657" ], [ "The Lord of the Rings: The Fellowship of the Ring\n(extended edition)\ni love how some films, particularly fantasy, just transports you into a completely different world and it’s like you’re right there with the characters, and in some way it is comforting even though the things you are witnessing aren’t very comforting to watch. the beautiful visuals of the worlds and the scores just do something to you.\nanyway i watched this many many years ago and then ago a few years ago so it was time for a rewatch cause as i was quite young i didn’t remember what i even thought of the film, and then i decided to watch the extended version instead and it didn’t even feel that long and it was quite wonderful.", "462" ] ]

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[ [ "Aggregate Data\nSince you're only given aggregate data, and not individual examples, machine learning techniques like decision trees won't really help you much. Those algorithms gain a lot of traction by looking at correlations within a single example. For instance, the increase in risk from being both obese and over 40 might be much higher than the sum of the individual risks of being obese or over 40 (i.e. the effect is greater than the sum of its parts). Aggregate data loses this information.\nThe Bayesian Approach\nOn the bright side, though, using aggregate data like this is fairly straightforward, but requires some probability theory.", "57" ], [ "If $D$ is whether the person has diabetes and $F_1,\\ldots,F_n$ are the factors from that link you provided, and if I'm doing my math correctly, we can use the formula: $$ \\text{Prob}(D\\ |\\ F_1,\\ldots,F_n) \\propto \\frac{\\prod_{k=1}^n \\text{Prob}(D\\ |\\ F_k)}{\\text{Prob}(D)^{n-1}} $$ (The proof for this is an extension of the one found here). This assumes that the factors $F_1,\\ldots,F_n$ are conditionally independent given $D$, though that's usually reasonable. To calculate the probabilities, compute the outputs for $D=\\text{Diabetes}$ and $\\neg D=\\text{No diabetes}$ and divide them both by their sum so that they add to 1.\nExample\nSuppose we had a married, 48-year-old male. Looking at the 2010-2012 data, 0.73% of all people get diabetes ($\\text{Prob}(D) = 0.73\\%$), 0.77% of married people get diabetes ($\\text{Prob}(D\\ |\\ F_1)$$= 0.77\\%$), 1.02% of people age 45-54 get diabetes ($\\text{Prob}(D\\ |\\ F_2) = 1.02\\%$), and 0.70% of males get diabetes ($\\text{Prob}(D\\ |\\ F_3) = 0.70\\%$). This gives us the unnormalized probabilities: $$ \\begin{align} P(D\\ |\\ F_1,F_2,F_3) &= \\frac{(0.77\\%)(1.02\\%)(0.70\\%)}{(0.73\\%)^2} &= 0.0103 \\ P(\\neg D\\ |\\ F_1,F_2,F_3) &= \\frac{(99.23\\%)(98.98\\%)(99.30\\%)}{(99.27\\%)^2} &= 0.9897 \\end{align}$$ After normalizing these to add to one (which they already do in this case), we get a 1.03% chance of this person getting diabetes, and a 98.97% chance for them not getting diabetes.", "945" ], [ "Before you do anything, it's good to assess which of the following three categories your NaN rows fall into:\n1. Missing Completely at Random (MCAR),\n2. Missing at Random (MAR),\n3. Missing Not at Random (MNAR).\nMCAR\nIf they're MCAR that means the \"missing data\" (i.e., the data that would have been there if it had been entered correctly or received in the first place) has the same distribution of values as the non-missing data. For example, if there's a categorical column with four categories A, B, C, D, which have a combined ratio a:b:c:d in the non-missing data, then any missing data will have the same ratio a:b:c:d. In this case it's possible to impute the missing values using the distribution of the non-missing values.\nMAR\nIf the missing data is MAR then there is a possibility that the distribution of the missing data and the non-missing data is different. This can occur, for example, in medical tests, where a test that is often performed on older people, who get worse test results, is less likely to be performed on younger people, who get better test results. In this case, it's not possible to impute the missing values with the distribution of the non-missing values.", "964" ], [ "However, if a variable in your model is largely responsible for the change in distribution, in this case age, you can stratify your data by that variable, so that within your chosen strata the distribution for the missing and non-missing data are basically the same. That means that within your strata you can still use imputation to predict the missing values.\nMNAR\nFinally, if your data are MNAR then there is a possibility that the distribution of the missing data and the non-missing data is different, but your model doesn't contain another variable that can explain that difference and stratify your data. This situation can occur when the chance of recording a variables value is dependent on the value of that variable and that variable alone. For example, alcoholics may decline to answer a question on alcohol consumption out of embarrassment, whereas T-Totallers would have no issue answering. In this case, you have to come up with some sort of model that explains why the data might be missing and use that to impute values for the missing data.\nIf you'd like to know more about the above three definitions read this article, and this web page: MNAR,\nOnce you know NaN Category\nOnce you know what category your missing data falls into, you can make a decision about whether or not to delete the rows or impute the data. In your specific case, I would find out if your data is either MCAR or MAR and, if it is, delete it. This data is known as \"ignorable data\" and, as it's only 2.6% of all data, its exclusion shouldn't make an appreciable difference to the effectiveness of your model.\nIf it's MNAR then you need to figure out what the pattern behind its exclusion is and use that to impute the data. For more information on the various methods of imputing data look at the following article from Towards Data Science.", "964" ], [ "Well, sometimes the features simply do not provide enough information to get 100% accuracy (like in your case), even with a model a flexible as the Decision Tree.\nThe Decision Tree works by trying to split the data using condition statements (e.g. A < 1), but how does it choose which conditional statement is best? Well, we want the splits (conditional statements split the data in two, so we call it a \"split\") to split the data so that the target variable is separated into it's different classes, that way when we get a new instance and use the tree to classify it, we can say \"This instance is 100% this class\", because the leaf node only includes instances of this class. In other words, we want the conditional statements to split the data so that the nodes only include instances of one class. This is what impurity measures, how impure a node is (so the less impure the better).\nSo, now that we can measure the impurity of the data at a node, we can score conditional statements. All we have to do is simply get the weighted sum of impurity on both sides of the split:\n$$\\frac{m_{left}}{m}I_{left} + \\frac{m_{right}}{m}I_{right}$$\nwhere:\n* $I_{left/right} = $ The impurity of the data on the left/right side.\n* $m_{left/right} = $ The amount of data on the left/right side.\n* $m = $ The total amount of data.\nWe can call this the cost function of a split, the split with the lowest cost is considered the best.\nSo, when the Decision Tree is searching for the best split, it will consider every feature, splitting it at every value we see that feature take in the data, and assign every combination a cost.", "964" ], [ "Once it has gone through all possible combinations, it'll simply choose the conditional statement with the lowest cost.\nHowever, if the lowest cost found is no better than the impurity of the current node, that means there's nothing it can do to make the data here more pure, and so it'll stop trying to do so and just make the next node a leaf node.\nLet's manually go through your toy dataset together to see this algorithm in action: ``` A B C | D\n1 1 1 | 0 1 1 0 | 0 1 1 0 | 1 1 0 1 | 1 ``` The first thing we have to establish is what impurity measure we'll use. A good default is \"Gini Impurity\", so I'll be using that one:\n$$G_i = 1 - \\sum_{k=1}^{n}p_{i,k}^2$$ where:\n* $G_i = $ The gini impurity at the $i^{th}$ node.\n* $p_{i,k} = $ The ratio of target class $k$ instances among all instances in the $i^{th}$ node.\nNow, let's begin building the tree:\nThe first thing we have to do is find every combination of feature and value:\n(A,0), (A,1), (B,0), (B,1), (C,0), (C,1),\nthen, we split the data using every combination and measure it's cost. Since all the features are binary here, splitting at (A,0) and (A,1) is the same thing, so we just need to measure one of the two, making us not need to specify what value we're splitting at.\nLet's measure the cost of B:\nFirst, we measure the impurity where B = 0, there's only one instance, so the gini impurity is $$1 - (\\frac{0}{1})^2 - (\\frac{1}{1})^2 = 1-1 = 0$$So it's completely pure. Then, for B = 1, the impurity is $$1 - (\\frac{2}{3})^2 - (\\frac{1}{3})^2 = 1 - \\frac{5}{9} = \\frac{4}{9}$$Finally, to get the cost, we just need to get the weighted sum of $0$ and $\\frac{4}{9}$: $$\\frac{1}{4}0 + \\frac{3}{4}\\frac{4}{9} = \\frac{1}{3}$$ There we have it! The cost of using B as the first split is $\\frac{1}{3}$. As it turns out, this is the lowest cost we can get (A and C have a cost of $0.5$), so that will be our first node in our tree. ``` Left = 0 Right = 1\nB / \\ ? ?", "743" ], [ "Well, there are a few ways to do the job. Here are some I thought of: 1. Scatterplots with noise:\nNormally, if you try to use a scatter plot to plot two categorical features, you would just get a few points, each one containing a lot of instances from the data.", "964" ], [ "So, to get a sense of how many there really are in each point, we can add some random noise to each instance: ```python import numpy as np import seaborn as sns import matplotlib.pyplot as plt %matplotlib inline\nThis is to encode the data into numbers that can be used in our scatterplot\nfrom sklearn.preprocessing import OrdinalEncoder ord_enc = OrdinalEncoder() enc_df = pd.DataFrame(ord_enc.fit_transform(df), columns=list(df.columns)) categories = pd.DataFrame(np.array(ord_enc.categories_).transpose(), columns=list(df.columns))\nGenerate the random noise\nxnoise, ynoise = np.random.random(len(df))/2, np.random.random(len(df))/2 # The noise is in the range 0 to 0.5\nPlot the scatterplot\nplt.scatter(enc_df[\"Playing_Role\"]+xnoise, enc_df[\"Bought_By\"]+ynoise, alpha=0.5)\nYou can also set xticks and yticks to be your category names:\nplt.xticks([0.25, 1.25, 2.25], categories[\"Playing_Role\"]) # The reason the xticks start at 0.25\nand go up in increments of 1 is because the center of the noise will be around 0.25 and ordinal\nencoded labels go up in increments of 1.\nplt.yticks([0.25, 1.25, 2.25], categories[\"Bought_By\"]) # This has the same reason explained for xticks\nExtra unnecessary styling...\nplt.grid() sns.despine(left=True, bottom=True) [![Scatterplot with noise][1]][1]<br><br> 2. **Scatterplots with noise and hues:**<br> Instead of having both axis being feature we can have the $x$ axis be one feature and the $y$ axis be random noise. Then, to incorporate the other feature, we can \"colour in\" instances based on the other feature:python import numpy as np import seaborn as sns import matplotlib.pyplot as plt %matplotlib inline\nExplained in approach 1\nfrom sklearn.preprocessing import OrdinalEncoder ord_enc = OrdinalEncoder() enc_df = pd.DataFrame(ord_enc.fit_transform(df), columns=list(df.columns)) categories = pd.DataFrame(np.array(ord_enc.categories_).transpose(), columns=list(df.columns))\nxnoise, ynoise = np.random.random(len(df))/2, np.random.random(len(df))/2\nsns.relplot(x=enc_df[\"Playing_Role\"]+xnoise, y=ynoise, hue=df[\"Bought_By\"]) # Notice how for hue\nwe use the original dataframe with labels instead of numbers.\nWe can also set the x axis to be our categories\nplt.xticks([0.25, 1.25, 2.25], categories[\"Playing_Role\"]) # Explained in approach 1\nExtra unnecessary styling...\nplt.yticks([]) sns.despine(left=True) ```\n1. Catplots with hues:\nFinally, we can use catplots, and colour in fractions of it based on the other feature: ```python import seaborn as sns import matplotlib.pyplot as plt %matplotlib inline\nsns.histplot(binwidth=0.5, x=\"Playing_Role\", hue=\"Bought_By\", data=df, stat=\"count\", multiple=\"stack\") ```", "988" ], [ "Do you have some kind of outcome associated with the dataset? By 'top 10 most important features', do you mean most important in achieving a specific goal? If you have some kind of outcome column (a score or pass/fail) you can solve this through a good old fashioned regression technique. If you don't, you might have to redefine what importance means and use a technique like PCA to find the most variable features.\nA worked example: What is most important for students to pass a test?\nFor this made up example, we are tracking 30 students and seeing what is more important for passing a test, intelligence (IQ) or study time (in hours). The code below is in R, but I'm just using it to illustrate the process.\n# Generating some sample data\nset.seed(300)\nIQ <- as.integer(rnorm(30,mean=100,sd=10))\nstudy_hours <- as.integer(rlnorm(30,mean=1.5,sd=0.75))\nscore <- as.integer(100*tanh( 0.0012*(6*IQ + 20*study_hours\n+rnorm(30,mean=150,sd=10))))\nIQ study_hours score\n1 113 3 78\n2 108 5 80\n3 104 2 75\n4 107 3 76\n5 99 8 80\n6 115 5 80\n7 108 2 77\n8 103 4 76\n9 112 3 78\n10 103 1 73\n11 122 8 84\n12 99 2 72\n13 86 3 69\n14 100 6 77\n15 105 12 84\n16 100 12 83\n17 114 9 84\n18 87 7 74\n19 97 6 76\n20 102 5 77\n21 96 9 79\n22 106 15 86\n23 96 1 71\n24 101 4 76\n25 88 4 71\n26 96 4 75\n27 102 2 74\n28 113 4 79\n29 99 2 73\n30 110 2 77\nBoth IQ and study time seem to have a positive effect on exam score. But how do you tell which one is more important? Linear regression will give you an equation that fits a straight line to the data, and the slope of the line in each direction gives the relative importance of that feature.\nBut first you have to standardise the numbers, otherwise the bigger set of numbers (IQ) is going to throw things out of whack.\n# Standardising the variables.\n# (You take the number, subtract the mean and divide by the standard deviation)\nstandardisedIQ <- (IQ-mean(IQ))/sd(IQ)\nstandardised_study_time <- (study_hours-mean(study_hours))/sd(study_hours)\n# Perform linear regression. Output variable is score and input variables are\nstandardised IQ and standardised study time\nL <- lm(score ~ standardisedIQ + standardised_study_time)\nL\nThe output is:\nCoefficients:\n(Intercept) standardisedIQ standardised_study_time\n77.133 2.507 3.182\nwhich can be read as: Everything else being equal, the average score is 77.1, and IQ has an 'effect' of 2.5 and study time an 'effect' of 3.2. Since the study time number is larger, study time has more of an effect than IQ in this particular exam.\nHow does this translate to your problem? In your case, you have 100 variables.", "650" ], [ "Just standardise them, set up the appropriate regression on those 100 variables and the outcome variable, and choose the top ten variables with the highest (absolute value) scores.\nThe specific type of you use will depend on what outcome variable you have. If it's a pass/fail rather than a score, you want to use logistic regression.\nAs far as I can tell, doing things this way isn't completely statistically sound. However, if your client is non-mathematical and only wants 'an idea' of what the different features are doing, that shouldn't matter.\nIf you do not have any usable outcome variables, using PCA (principal component analysis) may help. It will highlight the 'variability' or 'salience' of the various features, but not necessary their importance towards any goal. Keep in mind that there are a bunch of caveats with using PCA, and doing some sort of data standardisation is necessary if you're using units of measurement (i.e. one feature is measured in metres, another in seconds, etc.).", "964" ], [ "When you say\n\"...how various aspects of a movie contribute to its gross revenue.\"\nI'm assuming you want\n\"If I were to change $A_1$ of a movie, how would it's gross revenue be affected?\"\nWhich is a causal statement. With this assumption in mind, I will rewrite Approach 1 and 2;\nApproach 1 - Don't control for anything, and measure the effect $A_1$ has on revenue\nApproach 2 - Control for everything, and measure the effect $A_1$ has on revenue.\nBoth have fundamental problems, stemming from how the data was generated, and how attributes affect each other;\nApproach 1's problem is confounders, attributes that affect both $A_1$ and revenue.\nHere's a good example of a confounder:\nIt has been seen that children with a larger shoe size have a better reading ability. The trick is that age affects both reading ability and shoe size, the older you get, the larger your shoe size, as well as (generally) better reading ability. That make age here a confounder of shoe size and reading ability.\nSo, for the movie example, genre might affect runtime as well as revenue, making it a confounder of runtime and revenue.\nApproach 2's problem is colliders (and potentially mediators). A collider is an attribute that $A_1$ and revenue affect.\nFor example if we say that both talent and beauty contribute to an actor's success, then, if we look at successful actors, we will see a negative correlation between beauty and talent (basically saying being beautiful makes you less talented). The reason for this is because, if we see an actor is unattractive, that increases our belief that the successful actor is very talented instead. Here, success was the collider, and when we controlled for it, it warped our connection between talent and beauty.\nAn example in the movies might be that the number of reruns of a movie is affected by revenue and runtime, making number of reruns a collider of the two, thus, if we control for it, it will warp the relationship between runtime and revenue in ways we don't want.\nAnother potential problem with Approach 2 is mediators, attributes that affect revenue and are affected by $A_1$\nAn example of a mediator would be Fire → Smoke → Fire Alarm.", "57" ], [ "Fire creates Smoke which triggers the Fire Alarm. If we were to control for Smoke, we would be removing the mechanism Fire uses to trigger Fire Alarm, which would lead us to believe that Fire can't trigger Fire Alarm (which is technically true, fire itself doesn't trigger the Fire Alarm, fire doesn't have a direct effect on Fire Alarm).\nWe have to be aware of the mediators and that controlling for them turns the total effect of $A_1$ on revenue into the direct effect $A_1$ has on revenue.\nSo, If you're looking for the total effect, then Approach 2 falls victim to mediators as well, if you want the direct effect, that would make Approach 1 falls victim instead.\nThese are the fundamental flaws with Approaches 1 and 2, but there's also the problem of too small bin sizes, that would just be mostly noise (nicely explained in <PERSON> answer). You can fix this by either getting more data or making more assumptions (e.g. assuming 10 minutes in a movie's runtime won't make a difference, and binning runtime into 10 minute wide bins).\nSo, in conclusion (for Approach 1 and 2), If you want to do something like Approach 1 and 2, you need to do a mix of the two. Find out what attributes are confounding and control for them, then, you can safely measure how revenue changes as $A_1$ changes, and rank the attributes based on that. Of course, to find the confounders, you need to know the model from which your attributes were generated from (known as a \"Causal Model\"), which can be tough to find.\nThere's a great book on of this, \"The Book of Why\" by <PERSON>. I highly recommend it, if you're interested in this sort of thing.\nNow, let's talk about Approach 3, the more volatile approach I would say;\nThe thing is, many algorithms can measure \"feature importance\", and it's hard to say what exactly the algorithm looks for when it says \"important\" (one thing is for certain though, it won't measure \"If I were to change $A_1$ of a movie, how would it's gross revenue be affected?\").\nBut if you want an answer, Random Forests don't make any assumptions about the data, and have a nice way of measuring feature importance. However of course, they are highly parametric, and will just memorize (i.e.", "57" ], [ "I'll start with a brief introduction of the statistics before addressing the specific questions posed.\nLet's say you have conducted an experiment, and from it obtained a data distribution. However, raw data by itself is not exactly interesting; instead, you want to be able to extract some meaningful (i.e. statistical) result from the data.\nThe process by which this is done is known as statistical inference: given some set of data, $\\boldsymbol{X}$, one wishes to test how well it can be described by a model, $M(\\boldsymbol{X};\\boldsymbol{\\Theta})$, where $\\boldsymbol\\Theta$ are the parameters of the model, whose true values are unknown a priori. To extract likely values of the model parameters given the observed data, one defines the likelihood function: \\begin{equation} L(\\boldsymbol{\\Theta};\\boldsymbol{X}) \\equiv M(\\boldsymbol{X};\\boldsymbol{\\Theta}), \\end{equation} which differs from the model in that the data is fixed, while model parameters are treated as random variables.\nA common method of inference is that of maximum likelihood estimation (MLE), which states that the set of parameter values, $\\boldsymbol{\\hat\\Theta}$, that result in maximisation of the likelihood function provides an estimate of the true parameter values.", "915" ], [ "Confidence regions can then be constructed around the $\\boldsymbol{\\hat\\Theta}$ using the likelihood ratio test.\nAnother method is known as Bayesian inference, which makes use of <PERSON>' theorem: \\begin{equation} P(\\boldsymbol{\\Theta}|\\boldsymbol{X},M) = \\frac{P(\\boldsymbol{X}|\\boldsymbol{\\Theta},M) P(\\boldsymbol{\\Theta}|M)}{P(\\boldsymbol{X}|M)}\\,, \\end{equation} where $P(\\boldsymbol{\\Theta}|\\boldsymbol{X},M)$ is the posterior probability distribution, $P(\\boldsymbol{X}|\\boldsymbol{\\Theta},M)=L(\\boldsymbol{\\Theta};\\boldsymbol{X})$ is the likelihood function, $P(\\boldsymbol{\\Theta}|M)=\\pi(\\boldsymbol{\\Theta})$ is the prior probability distribution, and $P(\\boldsymbol{X}|M)=\\mathcal{Z}$ is the Bayesian evidence, which normalizes the posterior distribution. Maximum a posteriori (MAP) estimation prescribes a method of estimating model parameters through maximisation of the posterior probability. However, note that it is equivalent to just maximise the likelihood times prior, \\begin{equation} L(\\boldsymbol{\\Theta})\\pi(\\boldsymbol{\\Theta}), \\end{equation} since constant factors (such as the evidence) do not shift the location of the maximum in parameter space. So in a practical application of MAP for parameter estimation purposes, one only needs to define the likelihood function and prior distributions: the former according to whichever theoretical model under test, and the latter defining the search region in parameter space.\nwhat do authors mean by \"prior\"? Does this term \"prior\" refer to the bayesian formula...So, if this is the case, the prior of parameter $\\theta_i$ would represent the probability $p(\\theta_i)$, wouldn't it ?\nYes, they are referring to the prior that appears in <PERSON>' theorem, though note that this is a probability distribution.\nIn this case, what they seem to mean is that they have chosen $\\delta$-distributions as priors for the $\\omega_b$, $\\omega_{cdm}$, $h$, $A_s$, $n_s$ and $\\tau_{reio}$ parameters. Put more simply, what they show here is the model distribution when all parameters are fixed to certain values.\nGiven Likelihood is proportional to posterior (is it right from above equation (1) ?), I have to know the theorical model to compute Likelihood ?\nYes, you need to have a theoretical model before the likelihood function can be defined.\nI mean, to get $p(\\theta|d)$, I have to generate the probability $p(d|\\theta)$ assuming I know the value of $\\theta$ parameters, don't I ?\nThere seems here a paradox : I compute the posterior $p(\\theta|d)$ to estimate $\\theta$ parameter on one side but I have to know precisely the probability $p(\\theta)$ on the other side.", "915" ], [ "The first thing to do is to treat the bias ($\\rho$) as a weight on an extra input whose activity is always 1 so that you won't need a separate learning rule for the bias and then the decision for your binary threshold outputs a 1 iff $\\sum\\limits_{i=1}^{3} w_i x_i \\geq 0$\nTo learn the weights of perceptrons, you are right to start with random weights. The remainder of the procedure is to do the following: if for an input your weights correctly classify an output, you leave the weights alone. If, however, you incorrectly output a zero, add the input vector to the weight vector. And on the other hand, if you incorrectly output a 1, subtract the input vector from the weight vector. I would be able to show you an example run with your inputs and random weights above but you're missing the outputs which map to the inputs in order to correct the weights.\nAlso, note that the above procedure gives you a correct set of weights iff one exists.", "964" ], [ "Otherwise, the learning procedure will fail and you will eventually find it impossible to classify one of the inputs.\nEDIT: Here's another example to try and explain things. Let's use initial weights where $w = (w_1, w_2, w_3) = (1, 0, -2)$, letting $\\rho = 0$, with:\nTarget: $t_1 = 1$, $t_2 = 1$, $t_3 = 0$, $t_4 = 1$, $t_5 = 0$\nInput: $x_1 = (1,0,1)$, $x_2 = (0,1,1)$, $x_3 = (1, 0, 0)$, $x_4 = (1,0,1)$, $x_5 = (1, 0, 0)$\n$y_1 = wx_1 = 1\\times 1 + 0\\times 0 + -2\\times1 =-1 \\leq \\rho$ --> outputs a 0, which does not equal $t_1$. In this case, we add the input to the weight vector so $w\\prime = w + x_1 = (1+1,0+0,-2+1) = (2,0,-1)$, $w = w\\prime$\n$y_2 = wx_2 = 0\\times 2 + 1 \\times 0 + 1\\times -1 = -1 \\leq \\rho $ --> outputs a 0, which does not equal $t_2$. In this case, we add the input to the weight vector so $w\\prime = w + x_2 = (2,1,0)$, $w = w\\prime$\n$y_3 = wx_3 = 1\\times 2 + 0\\times 1 + 0\\times 0 = 2 > \\rho$ --> outputs a 1, which does not equal $t_3$. In this case, we subtract the input from the weight vector so $w\\prime = w - x_3 = (2-1,1-0,0-0) = (1,1,0)$, $w = w\\prime$\n$y_4 = wx_4 = 1\\times 1 + 0\\times 1 + 1\\times 0 = 1 > \\rho$ --> outputs a 1, which equals $t_4$ so the weight vector remains unchanged.\n$y_5 = wx_5 = 1\\times 1 + 0\\times 1 + 0\\times 0 = 1 > \\rho$ --> outputs a 1, which does not equal $t_5$. In this case, we subtract the input from the weight vector so $w\\prime = w - x_5 = (1-1,1-0,0-0) = (0,1,0)$, $w = w\\prime$\nFinal weight vector $w= (0,1,0)$", "945" ] ]

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[ [ "These are to the best of my knowledge, the physics of super human strength related to punching (if there is such a thing):\nTo start, when a human being punches, he/she generates force by one of the following:\nTorque - generate centripetal force by swinging the weight of the arm\nLeverage - pushing off the ground slightly and/or against one's own weight or speed\nIn order to generate escape velocity, a human being would not be able to use those means because:\nTorque - The person would have to anchor the centripetal force with their body somehow, so unless they have super-human obesity (or density) or super-human physics, they're not really going to be able to aim using torque.\nLeverage - The person's feet and body would sink into the ground like a bullet and their punch would miss (which would be funny)\nSo basically you need to answer this question: Where does the super force come from and when does it work?\nWhere does it come from?\nIf the force comes ex nihilo or in another way that does not obey the laws of physics, then all bets are off, but then you can have someone get punched into the atmosphere (totally worth suspending physics).\nA Dilemma\nLet EV = <PERSON>'s required to generate escape velocity\nYou are stuck in a catch-22 I like to call the super-cancelling dilemma. If a person can punch with super human force, they can also absorb that amount of force (dissipating it \"into the universe\" or whatever) otherwise they have to break the laws of physics. So the puncher generates EV newtons by creating and simultaneously absorbing that force in his/her own body thus reaching the punchee with the force and transferring it. But here's the catch 22...\nIf BOTH brawlers can absorb that amount of energy, they will not be able to force each other at all (EV - EV = 0), and the fight wouldn't appear to be super human unless a regular object or person got in the way in which case it would be obliterated.\nThe one brawler would need superhuman means, so the ball is back in your court since you got them into this predicament to begin with - now you have to get them out.\nThe fight would look normal if they could absorb exactly the same amount as they could dish out, so if one is slightly stronger than the other but multiplied by hundreds of thousands of Newtons, you're talking about guys flying through the atmosphere again, but that means the one person must be roughly twice as strong as a super-human who can generate EV or more force (2EV - EV).", "621" ], [ "If there is some fluctuation (as there is in a real fight), and that fluctuation can be in the thousands of Newtons, now you're talking about a one punch fight. One guy punches punches with EV + 1 Ns and the other guy absorbs Ev - 1 Ns of force. Well, if they are immutable, now you've got that guy flying with ~2000 Ns in whatever direction he was struck.\nFurther considerations\nIf a punch misses, can that puncher \"reabsorb\" the force even though they absorbed it once already to create it, or will that person go flying in the direction of their swing?\nCan the super-human body absorb at the same ratio as a regular human? if so, it will appear like a normal fight. If not, they'll obliterate one another at the first punch with a only a tiny variation relative to the normal godly force.\nIf there is an angle, deflection, speed, or interference at all, you need to recalculate (in other words, you are facing a myriad of variables)\nSo No, that's not possible based only on the parameters you gave. They would need a way to create and absorb the force at the same time.", "621" ], [ "We can do some simple math here to see what our constraints really look like.\nLet's assume the meteor is mostly made of iron, because I heard that's a common composition in a museum somewhere. Assuming spherical shape, it would be around 3.3 * 10^16 kg. The kinetic energy of the meteor would therefore be 5.3 * 10^24 Joules. We'll assume this is the Kinetic energy at contact with zero gravitational potential energy left. Out of curiosity though, since the escape velocity of Earth is 11.2 km/s, 11.2^2 = 125 and 18^2 = 324, and so gravitational potential energy accounts for at maximum 38% of the total meteor energy.\nNow the one fundamental thing you have to keep in mind here is this: If you really really really want to stop the meteor instead of deflect it, then that is the raw amount of energy you have to deal with. You can dissipate it, you can reflect it, you can eat it (destruction), but no matter what, that is your the raw quantity of your challenge. This is a lot of energy. It is equivalent to 25 million Tsar Bombas. How do you absorb the energy of 25 million Tsar Bombas with a net? <PERSON> even describes this amount of energy as 11 times the estimated energy of the Chicxulub meteor impact that destroyed the dinosaurs (granted, our calculations are very rudimentary, e.g. sphere of iron). How do we stop 11 Chicxulub asteroids with a net? This is the question you may as well be asking.\nThankfully though, you have a very accommodating budget. So let's think of a solution!\nAgain, to emphasize, we have to dissipate energy. When you catch a baseball in a glove, or hit a tennis ball with a racket, the energy is dissipated through sound waves, stress, strain, and friction heat of the catching device. In more extreme catching scenarios, the catching device is specifically designed to break in intentional ways, in order to dissipate large amounts of energy (like table saws with flesh sensors or crumple zones in vehicles).", "921" ], [ "Probably our best approach for a net is to make it out of something really strong, but not so we can hold the meteor in the sky, rather so the meteor has to spend a ton of energy when it breaks the net.\nHere is how I envision it\nYou make a net out of tons of carbon nanotubes. You dissipate the energy by planning on the carbon nanotubes breaking. I'm no mechanical engineer, but I'll see what I can do with rough calculating. Apparently researchers have developed high-strength carbon nanotube films with up to 9.6 GPa of tensile strength before breaking. Say in the next 50 years we get that to 10 GPa (being conservative). It looks like carbon nanotubes usually survive about 15% to 20% stretching before they break. So if we have a net that is carbon nanotubes in one single direction, in a 10km by 10km square, then if force is applied down on the net evenly (such that tension is the main force at play, and we ignore shear forces), we can find out how much energy it costs to break the net at any given net thickness.\n* Pressure when net breaks = 10 GigaNewtons / meter ^ 2\n* Force when net breaks = net thickness * net width * pressure when net breaks\n* Energy when net breaks = force when net breaks * distance over which the force is applied\nSo\n* Energy when net breaks = (15% * 10km) * (10 km) * thickness * (10 GigaNewtons / meter^2), or in other words...\n* Energy when net breaks / thickness = 1.5 * 10 ^ 17 Newtons\nAnd so if we want to stop a 5.3*10^24 Joule projectile, we need a carbon nanotube net 10 Km long, 10 Km wide, and........\n36.... MILLION meters thick!\nSee here\nI'm actually impressed!! My first edit of this answer was so incredibly hilariously wrong! at 18 m/s we need 3.8 meters thick nanotube...... but at 18 km/s we need a 36 million meter thick net! Again, at 10 km wide and 10 km long.... 36 million meters is 5.6 times the radius of the Earth.\nYou can also fine tune it, if you look at the formulas. If you increase the stretch distance, you don't need as thick a material. But it will simply never compensate for that raw amount of energy. This meteor catching exercise is basically futile. but fun in any case!\nThe way the terms work out, you can squint your eyes and make a different net depending on how you interpret it.", "921" ], [ "Jumping on <PERSON>'s answer, this is physically difficult (but not impossible) and what most suggestions have said so far is somewhat incorrect realistically. This is because of <PERSON>'s Laws (Specifically the Third here)\n1. For every action, there is an equal and opposite re-action\nThis means in our example two things:\n1) When a mass moves linearly, as in \"rocket-firing\" it, it also creates an equal force in the opposite direction. So look at the ground here:\nThat air and fuel is moving with a lot of force! Neglecting the exhaust problem of a steam rocket, a human weight (~62 kilo says google) hammer hitting forwards at fast velocities would hit a human forwards with an imparted force, but the imparted force is equally applied to the wielder backwards, including joints and bones, and in the opposite direction. So hitting forwards with some force would push you backwards with the same force. Breaking concrete? Not useful for a human wielder bluntly, unless you had some sort of intricate counter weight.\n2) When a mass moves from a \"tether\" like a handle, it exerts an opposite rotation force. For example, <PERSON> has some interesting ways of killing megafauna, swinging them by the tail!\nHe's got some strong legs! Suppose my hammer \"jerks\" forward from my arm by rotation. Something has to counter-balance that, and it's not going to be my wrist if the force could break bones.", "621" ], [ "Maybe my muscles, but probably not from an arm all the way down...\nMy conclusion is that a blunt \"warhammer\" would not work for this with a human wielder holding the force. And about that concrete: it's a fun fact that a human femur, the largest bone in the human body, is about as strong as concrete. Not stronger: you won't do it bluntly.\nNeeds to be effective in hurting and killing humans, mega-fauna, and break through concrete and steel.\nThe more gears, the better.\nBut of course, I neglected two thirds of the important laws.\n1. Force is equal to the change in momentum per change in time: Force is equal to mass times acceleration\nAre you familiar with flywheels? You could use a flywheel churned by a steam engine and TONS of gears to do a torque differential - then impart its momentum by having it strike something or \"gear stop\" suddenly. Say the flywheel is ~150-200lbs, the bullet-shaped hammer head is ~30lbs, that's a lot for the rest of the contraption - but it would be more like a siege weapon.\nSomething that would break concrete could be sharp, but not steel. The steel would bend under mass but jackhammers are no good, even if it was ultra-hard like Tungsten. It would need to be blunt because steel doesn't chip away to my knowledge, and steam isn't hot enough to do something heat wise to steel (It's at least 212 F, but steel melts > 1000 F, that steam would cut out of pipes and slice people but even water has a hard time cutting steel under pressure - unless they found and rigged up a water-jet).\nAnother idea is two hammers on a pivot that rev up and hit, maybe on some sort of tank. But that would be a lot bigger, I should think - maybe something you could put on trained mega-fauna or a tank of some sort.\nAnyways, this is my mostly realistic answer. But this isn't the Physics SE.", "621" ], [ "Everyone seems to be going fairly high tech or require some special requirements of the environment such as low gravity for such a system to work. But there are real-world options.\nSo you want a slow moving ballistic (= unpowered) projectile weapon with a range of at least 50 meters that can inflict fatal wounds. Let's explore some options.\nThe Math\nI'm using [this tool][1] to calculate distances, angles and timing.\nYou said that at 20 meters, a human should be able to dodge. Let's say it takes about 1 second to recognize the projectile and move out of the way. Let's also assume that the humanoid aliens are about our size and fire their weapons from about 1.7 meters in height.\nIf you were to fire straight at the target - so at a 0 degree angle in respect to the ground, to reach a distance of about 20 meters you would need to fire the projectile at 35 meters per second and you would hit the targets ankle at 0.58 seconds after firing.\nThrough googling, we know that to maximize distance we need to fire at 45 degrees and we can then calculate that the slowest projectile that can hit at 20 meters needs to travel at about 14 meters per second. This takes 2.177 seconds and since the projectile is coming from above, it might hit more than just the ankle.\nFor 50 meters, we need at least 22 m/s and it takes 3.3 seconds. So just to be safe, let's say the maximum firing velocity is 25 m/s, giving us a maximum range of 65 meters. Since the aliens are out for blood, they always throw at this velocity and adjust the angle for closer targets.\nSo at 50 meters with a 25 m/s projectile the aliens can fire at an angle of 24 degrees and it takes 2.23 seconds to reach the target. At 20 meters distance the alien can fire at 5 degrees with a flight time of 0.85 seconds. 0.85 seconds might not be enough to reliably dodge, but someone with fast reflexes can probably still do it.\nRegular arrows at about 70 or more m/s are too fast, hitting something at 20 meters away in 0.25 seconds.", "347" ], [ "A baseball thrown by hand by a professional player can travel at 40 m/s giving us 0.58 seconds to dodge at 20 meters (incidentally, the batter is standing even closer and can react well enough to hit the ball with his bat. That's a good sign that your humans can dodge within 1 second).\nA baseball isn't very deadly, but it shows that the speeds necessary can be achieved even without having assisting tools. For example, a throwing knife, while not being the deadliest weapon, already fulfills your requirements, although they loses effectiveness at range.\nDeadliness\nTo make a projectile deadly you need force, if there's enough force it will even penetrate the target. A bullet gets its force from its speed, a thrown rock gets its force from it's mass. Something like an arrow is neither very fast (at 70 m/s) nor massive, but by using a pointy arrow head, most of the force can be focused on the very tip of the arrowhead which can then penetrate the target. If you use something like a blunt arrowhead, it won't be able to do much damage.\nSince you don't want speed, as long as it's more than 25 m/s, we have to focus on mass and being pointy.\nA Javelin, or throwing spear, is a weapon that fits your demands perfectly. The current world record in javelin throw is 98 meters. Using the previously calculated formulas, we can guess that this was thrown at about 31 m/s. These javelins are optimized for throwing distance, weight 800 grams and are only pointy enough to stick in the ground on landing. Even unoptimized, they occasionally hit one of the judges (as searchable on youtube), and occasionally penetrate and stick in them - deaths happen. Incidentally, apparently it's considered save enough for judges to stand on the field - I assume a testament to their dodgeability.\nIf they're made more pointy and their weight is increased, they should become both more deadly and even slower, so they better fit in your dodgeable at 20 meter criterion again.", "347" ], [ "Quantum Tunnelling\nWith the quantum tunnelling effect, you could tunnel through a barrier that it classically cannot surmount. This effect could be explained using the Heisenberg uncertainty principle. Here I will do a basic explanation: We have a green ball, two valleys (one below the another) and a mountain.\nWe push a little the green ball, it moves and falls in the first valley turning some of its potential energy into kinetic energy (light green line), then, the ball tries to climb the mountain using all its kinetic energy (yellow line), but sadly there isn't enough to climb the \"barrier\", and finally it falls in the metastable valley (red line and ball), a zone with some energy (not rest state) but not enough to climb the wall.\nBut if we think about energy, the ball can be in any place below the brown line because it doesn't need more kinetic energy to archive it, even more, reaching that states can turn potential energy into kinetic energy.", "621" ], [ "So, if we close the eyes, the uncertain principle said that this ball can be anywhere below the line, even inside the mountain! Using this principle and not looking elsewhere, the ball can do some tricky physics and move through the quantum tunnel in order to archive the real stable valley, where it doesn't have more potential energy.\nYour character can use this quantum tunnel in order to move instantly into zones below its brown line, which would be something like its chemical energy (stamina?) or maybe potential energy (can't teleport outside gravity wells), I don't know, that is your problem, not mine ;).\nOther ways could be:\nWarp Drive (Alcubierre drive)\nThere is a way to move faster than light without becoming pure energy, disintegrate or move through quantum and weird tunnels.\nIn soft sci-fi it's called warp drive, but in hard science it's usually referred to it as <PERSON> drive.\nIt collapses (make smaller) space towards it and expanses (make larger) space behind it in order to move less distance to archive further destinations.\nAnd extremely collapse and expansion of space towards and behind the teleporter respectively in a fast way could be experienced as a \"teleportation\".\nThe most realistic way to archive this could be manipulating gravity wells but it doesn't matter much.\nWormholes\nA wormhole connects two points in space-time themselves making something that could be described as a \"bridge\" between the points. By this way, you could travel almost instantly shortening the distance between you and your destiny. Also, you don't need to disassemble into molecules.\nLightspeed\nIf you become energy and travel at speed light, then become matter and reassemble philosophically speaking is a bit difficult to tell you if you are still alive, but at least it would be instantly for you. A particle travelling to lightspeed will not experience the pass of time.", "337" ], [ "At an in-principle level, no, it doesn't change the laws of physics, but it could change how we write the equations we use to describe them.\nThe laws of physics depend on the dimension Time. Any given clock is simply an instrument to measure time. The standard scientific unit, which we measure in, for time is the second.\nThe second is currently defined based on the vibration of certain atoms, but was originally defined as a fraction of an minute which was in turn defined as a fraction of an hour and so on - ultimately the second was originally based on the rotation of the earth. This could be considered one \"clock\" in the way you mean, if i understand you correctly.\nChanging the definition to be based on atomic vibrations allowed a more accurate definition of the size of the unit, but didn't change any fundamental physics, which ultimately relate to the dimension, time. Choosing to define it based on the vibrations of a different atom wouldn't have changed anything except the ease/accuracy/reliability with which we could measure the unit.\nIf you mean choosing a different unit size, other than what we currently know as a second, that would either have resulted in different choices of other unit sizes, or different looking fundamental equations - but they would only have differed by the constants needed to make the units work.\nTake <PERSON>'s Second Law.", "432" ], [ "The fundamental law is that force is equal to the rate of change of momentum. Given constant mass, that results in the familiar $$ F = ma $$ This is given use of kg for mass and meters per second per second for acceleration. However, if we wanted to measure acceleration in miles per hour per hour we could. The equation would then be $$ F = Kma $$ Where K is a constant (approximately 8052.985) to make the units work. The fundamental physics is the same.\nIn this case, we pretty much define the unit of force (Newtons) so that this holds (i.e. so that the constant K = 1 and can be left out altogether)\nIn practice, it would probably have resulted in changes in some other units to make things nicer, rather than just shoving in a bunch of constants.", "131" ], [ "Let's make a bunch of assumptions:\n* The largest primary is about 3 times bigger than Jupiter.\n* To really be a parent, the barycenter of a parent-satellite system must be within the parent.\n* Everything has approximately the same density\n* Orbital stability will magically work itself out (this will give us an upper bound)\nLet's call the twice the distance between the barycenter of a parent satellite system and the farthest extent of that system $D_p$ then the corresponding diameter for the subsystem $D_s$\nNow if the mass of the parent is $M_p$ and the mass of all the sub satellites together sum to $M_s$ then the requirement that barycenter be inside the parent yields:\n$$\\frac{M_s}{M_P}(D_p-\\frac12D_s)<\\left(\\frac{3M_p}{4\\pi\\rho}\\right)^\\frac13$$\nNow we know that for each parent none of the satellites can pass within the roche limit of the parent (the limit would actually be farther out due to the fact that the satellite system isn't solid but this will get us an upper bound) Lets call the diameter of the satellite system $D_s$ and the diameter of the parent system $D_p$. The Roche Limit gives:\n$$\\frac12 D_p>2.4\\left(\\frac{3M_p}{4\\pi\\rho}\\right)^\\frac13+D_s$$\nIf we claim that each subsystem is proportionate to the parent system then we have:\n$$\\left(\\frac{D_s}{D_p}\\right)^3=\\frac{M_s}{M_P+M_s}$$\nNow if we're trying to maximize the ratio of satellite mass to parent mass both of these inequalities should be equalities.\nSolving the system yields:\n$$D_p \\approx 2.6 D_s$$\nWhich means each successive moon would weigh $17$ times as much as the previous one.\nNow to get from a single atom moon to something 3 times the size of Jupiter would take: $$\\frac{\\ln\\left(3\\frac{1.89813 × 10^{27} kg}{1.6726219 × 10^{-27} kg}\\right)}{\\ln(17)}=42$$\nSo a system could have a maximum of 42 layers if we stopped at planets as the primary body.", "24" ], [ "Note however, this doesn't consider orbital stability and I have no doubt that even a system with 10 layers would be unstable on the time scale of a century.\nBigger\nIf we went up larger and larger, we could eventually incorporate black holes and then relativity plays havoc with the equations. However, I think that at the extremely large end, the expansion of the universe would distort and pull apart any orbits with radii on the order of billions of light years. So if we said that was the limit, then you could nest about $85$ layers, which is a lot, but I would hardly call that infinite.", "801" ], [ "The first problem with things in space is that everything moves fast - REALLY fast. For example, when you're near a planet, it's not that gravity is just too weak to pull you in - it's that you're going really fast and are counteracting gravity. To put a number to it, the international space station is traveling at 17,000 MPH.\nWith today's bi-propellant technology, if your shield were in the ISS's orbit and 90% of it was fuel and a missile was coming in behind you, the best you could do is go roughly 6,000 MPH in the other direction. However, you wouldn't actually go 6,000 MPH in the other direction: you would instead start falling back to Earth irritatingly quickly.\nChanging orbits with today's technology is very difficult.\nFurthermore, missiles flying in space are limited in what they can do because they have to carry all their fuel with them and accelerate it as well. This is why ballistic missiles are just ballistic: it's hard to affect changes in your trajectory when you would also have to carry fuel... so they just don't carry fuel and fly. We then lob little things at them to get in their way (EKV: Exoatmospheric Kill Vehicle, which is literally a thing that gets in the way of incoming missiles and runs into them - sound familiar?). These are incredibly expensive and rely heavily on the other target being predictable (in this case, ballistic) so they can minimize fuel usage and cost.\nBut you asked about the future...\nWhy did I say everything above? Because, in the future, if you have interplanetary travel, you must have solved the engine inefficiency problem and made it trivial to produce engines that can just do whatever you want.", "199" ], [ "However, your space ships still have structural issues, so they can only maneuver so quickly (unless, I suppose, the entire hull is lined with small engines so it can perfectly distribute forces). Presumably they may have also created some sort of an inertial damper to let them maneuver more quickly.\nSo let's say the enemy missiles and you both have the technology to make everything maneuver exactly how you want: you still lose because you're still playing defense and defense is always reactionary. If you get your shield right in the way of the missile (because your technology lets you do this effectively), then their missile would just change its course (because their technology also lets them do that). So you figure out how their algorithm works and make your shield predict theirs, so they change theirs. (Note: this is exactly how defense works nowadays too).\nRegardless of your level of technology between now and then, you CAN put a shield (whether it be something already in space or something like EKV) between you and them, but you always have a disadvantage that they will have the same maneuverability abilities and they control the game (again, defense is always reactionary). Plus your [big metallic] shield tends to get destroyed when it gets hit. Plus yours has to be a lot more expensive because it has to be more capable than theirs, so they can always exhaust your resources by just firing lots of them at you.\nA shield like that really isn't any more effective than shooting their missile with your missile - except that your missile doesn't have to happen to be in the right spot [as much] as a shield does.\nThis, by the way, is the genesis of energy weapons.\nSome more related examples\nUsing some numbers from wikipedia...\nThe US's \"Minuteman\" ballistic missiles cost $7 Million and [technically] only take a few people to operate them from a single silo.\nThe US's EKV program is hard to estimate the cost of, but [1] says they cost about $90+ Million each. It costs more than 10 times as much to defend against a single ICBM as it does to launch one. But this isn't the whole story, because to be able to hit a flying thing, you first have to detect the flying thing (with radars, which have limited range and precision) and transmit that information (which can be jammed) and launch against it, so you have the cost of all of those pieces too.\nThis cost differential has always been and probably always will be so.\n[1] - http://mostlymissiledefense.com/2012/07/24/ballistic-missile-defense-how-much-does-a-gbi-interceptor-cost-july-24-2012/", "898" ] ]

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[ [ "DIY Gift Photo Album\nIntroduction: DIY Gift Photo Album\nGood afternoon, dear viewers and readers! In today's instruction, I will show you how to make a gift photo album with your own hands. The photos used in this instruction were taken by me in the summer in Riga, Latvia, where I live.\nSupplies\nTo create a gift photo album, we need:\n* Photos square shape.\n* Coloured cardboard.\nEssential Equipment:\n* Scissors.\n* Ruler.\n* Pencil.\n* PVA glue stick.\nStep 1:\nLet's start creating a gift photo album. First you need to take a sheet of colored cardboard and mark it with a pencil and a ruler. In my case, colored cardboard has A4 format. We need to retreat 15 mm from the edge of the cardboard, then we need to mark 4 squares with dimensions of 103 by 103 mm. The remaining parts on the sheet will form the middle square when we glue everything together.\nStep 2:\nNext, with scissors, carefully and evenly cut a sheet of cardboard in half according to the markup.\nStep 3:\nThe resulting strips of cardboard need to be bent according to the markings. First, we bend the edge of the cardboard with dimensions of 15 mm in width. Then we bend all the other parts of the strip forming squares.\nStep 4:\nNext, glue two strips of cardboard together to form five squares. To create a long strip, you can use cardboard larger than A4 format.\nCardboard set includes two sheets of each color of the rainbow.", "294" ], [ "Thus, from two colored sheets, we form two long strips.\nStep 5:\nThen we coat the edge of one of the strips with glue and glue it in the middle of the second strip of cardboard. This process is repeated four times forming the shape of a cross.\nThe whole process of making cardboard strips is repeated for each color used.\nStep 6:\nThen we prepare the photos. The most important thing in the creation process is photos of the right size. In my case, the photographs are in the form of a square with dimensions of 100 by 100 mm.\nTrim off the extra white parts around the edges of the photo.\nThen we glue the photos to the resulting cardboard cross on all sides except for the middle part.\nThe whole process is repeated for each color used in the project.\nStep 7:\nNow let's prepare the photo box. The box must be formed according to the size of the resulting crosses with photographs approximately 350 mm in size. Cross length 309 mm + 40 mm to form the edges of the box.\nWith the help of a ruler and a pencil, we make markings along the edges of the cardboard, indent 20 mm on each side.\nThen we cut out the top and bottom part of the future box from cardboard.\nStep 8:\nNext, you need to bend the sides of the resulting parts of the box and then glue the curved edges together.\nStep 9:\nNext, inside the resulting box, you need to glue crosses with photographs. Crosses are glued to each other.\nStep 10:\nThen you can enjoy the finished result. For a more aesthetic and beautiful appearance of the box, it can be decorated with a gift bow.This gift photo album will delight you and your loved ones!\nThank you all for watching and reading the article. Don’t forget to like it and subscribe!", "163" ], [ "How to Make a Yarn Dog\nIntroduction: How to Make a Yarn Dog\nGood afternoon, dear viewers and readers! In today's instruction, I will show you how to make a dog from yarn threads.\nSupplies\nTo create a dog, we need:\n* Yarn.\n* Sock.\n* cotton pads.\n* Cardboard.\n* Metal cover.\nEssential Equipment:\n* Scissors.\n* Fine needle.\n* Dark thread.\n* Hot glue gun.\nStep 1:\nLet's start making a dog! First you need to take a sock and cut off the top with scissors.\nStep 2:\nNext, insert a metal cover inside the sock. The metal cover will be used as a bottom support.\nStep 3:\nAfter installing the metal cover, we insert cotton pads and sew everything with threads at the top of the sock.\nCotton pads should be stuffed to a distance of 13 cm long.\nStep 4:\nNext, we take a prepared cardboard 13 cm long, on which we wind the yarn. We need to make 20 turns around the cardboard. Then you need to tie all the threads of yarn together.\nAfter we remove the wound yarn and cut it in half in the middle. The whole process must be repeated 9 times.\nStep 5:\nAfter we need to take a prepared cardboard 16 cm long and make 80 turns around, after that everything needs to be tied and cut in half. This process needs to be done once.\nStep 6:\nNext, we wind 60 turns of yarn onto a prepared cardboard 4 cm long. We repeat this process three times, after we tie the yarn in the middle and cut it in half with scissors.\nUsing scissors, you need to cut the yarn and form it into balls.\nStep 7:\nUsing a hot glue gun, glue the prepared yarn around the body.", "879" ], [ "We also glue the yarn on top.\nStep 8:\nComb the threads of yarn up from the edge and pull them together with an elastic band, then cut off all excess.\nStep 9:\nNext, glue the remaining yarn to give the shape of the dog's muzzle. Then, using scissors, you need to cut out the nose, eyes and tongue from cardboard.\nStep 10:\nAt the end of the work, our yarn product needs to be given a more aesthetic appearance. herefore, on the resulting muzzle and head of the dog, we cut off the excess thread of yarn. Then glue the legs and tail in the form of balls in front and behind the body of the dog. The head of the dog can be decorated with a beautiful bow.\nStep 11:\nThen you can enjoy the finished result. This yarn dog will delight you and your loved ones!\nThank you all for watching and reading the article. Don’t forget to like it and subscribe!", "879" ], [ "Diy Origami Organizer Box Without Glue\nIntroduction: Diy Origami Organizer Box Without Glue\nHi Friends! In this project, I made an amazing, easy origami organizer box. This is really so easy and without glue. I made a desk organizer box.\nStep 1: Cut:\nFirst I cut a square sheet of paper from A4 size paper.\nStep 2: Fold:\nFold the corners of the paper. (1 and 2 edges overlap) It will be in the form of a triangle.\nStep 3: Rotate:\nRotate the triangular paper 45 degrees. You can determine the direction according to the numbers in the photo.\nStep 4: Fold 2:\nFold the sides of the triangle to the middle. So you will get a square shape. You can follow the numbers.\nStep 5: Turn and Fold:\nTurn over the back of the new square paper. Then fold only 2 layers of paper (at the bottom corner of the square) upwards.\nStep 6: Unfold\nUnfold all the parts you have folded and make the triangle in step 3 again.\nStep 7: Triangles:\nYou need 3 of these triangle. I did it in different colors.", "966" ], [ "But you can also use paper of the same colors.\nStep 8: Numbers:\nI wrote numbers on the left and right sides of the triangles. These are very important. This stage will create the organizer.\nStep 9: Inside and Outside:\nThe number 2 side of each triangle will go inside the corner number 1 of the paper on the left side (according to the photo).\nStep 10: Inside 2:\nThis rule applies to all edges. \"The number 2 side of each triangle will go inside the corner number 1 of the paper on the left side (according to the photo).\"\nStep 11: Fold All:\nThe organizer will look like a bowl. Turn the bottom. Interlace the corners of the paper to form the bottom of the bowl. For example: fold the yellow paper, then the blue, then the green, then the yellow, and again the blue and green paper.\nStep 12: Ready:\nOrganizer is ready. You can do it by using colorful, or just one color paper.\nStep 13: Finish:\nI made a bowl-shaped organizer without using any glue, tape, etc. Although it may seem difficult, you will find that it is very easy when you start doing it.\nStep 14: My Video:\nThis is my video about this project. You can also see all steps and all important details in this video.", "636" ], [ "Kawaii Mini Notebook Diy\nIntroduction: Kawaii Mini Notebook Diy\nHi Friends. I made a kawaii mini notebook in this video. There are so cute. I made easy kawaii mini notebooks in this video.\nStep 1: Materials:\nFoam (eva) or felt, A4 paper, glue, rubber rope (for crafts), scissors, ruler, markers.\nStep 2: From A4 to A5:\nCut the A4 size white paper into 2. We need half of A4, that is, an A5 sized paper.\nStep 3: A5 Size\nCut the A5 size paper into 2. Set one of the papers aside. It will be needed later.\nStep 4: Follow Numbers:\nFold the paper sequentially according to the numbers in the photo. Fold the dark red lines in the photos and then unfold them. 8 small boxes will be formed in 2 rows on the paper. You can see this clearly in photo number 8.\nStep 5: Cut:\nLeave 1 box from each of the 2 rows on the left and cut the paper right in the middle. You need to cut the part in the photo from the lines.\nStep 6: Fold:\nFold the boxes in every 2 rows in a zigzag pattern.\nStep 7: Glue:\nGlue the top 2 sides together with glue after folding.", "294" ], [ "(it looks like A and B in the photo)\nStep 8: Zigzag Snake:\nOpen the paper after the glue has dried. It looks like a zigzag-shaped snake as seen in the photo. Turn the middle part of the paper downwards (it should be towards you)\nStep 9: Cut 2:\nIn the same way, make another snake. (we reserved a paper for this before). Glue the zigzag snake-shaped papers together at the ends. (it looks like A and B in the photo)\nStep 10: Foam:\nCut a rectangle from the foam. Glue the white paper sheets (we just made) right in the center of the foam. If the foam is large, you can cut it with scissors.\nStep 11: Rubber Rope:\nGlue the 2 ends of the rubber rope to the inside of the foam.\nStep 12: Looks Clean:\nGlue the last of the paper sheets to the foam. So the mini notebook looks clean.\nStep 13: Decorating:\nWith markes, you can draw any patterns and shapes you want on the foam. It will look great without drawing any shape if you use glitter foam. You can draw with acrylic paints instead of markers.\nStep 14: Video Step:\nThis is my video about this kawaii mini notebooks. You can also see all details on my video.", "6" ], [ "Pattern Beaded Bracelet\nIntroduction: Pattern Beaded Bracelet\nGood afternoon, dear viewers and readers! Today I will show you how to make a pattern beaded bracelet.\nSupplies\nTo create a bracelet, we need:\n* Frosted opaque capri blue beads.\n* Opaque bisque white.\n* Opaque yellow beads.\n* Opaque orange beads.\n* Matte opaque orange beads.\n* Frosted opaque red beads.\n* Matte black beads.\n* Clasp for bracelet 20 mm long.\n* Carabiner clasp.\n* Extension chain.\nEssential Equipment:\n* Scissors.\n* Fine needle.\n* White thread\n* Loom for beads\nStep 1: Bracelet Pattern\nTo create a pattern for a bracelet, you can use specialized programs for beading. For my bracelet, I used the program Bead Tool 4. This program can be used for free without a save function or you can buy a paid service package.\nProgram download link https://www.beadtool.net/\nStep 2: Preparing the Loom\nFor the base, we collect the required number of threads on the loom, we pull it like strings. The number of these threads must correspond to the number of beads along the width of the product + 1 thread. There are 11 beads in our bracelet, which means we collect 12 threads. They are located at a width sufficient for a convenient location of the beads.\nStep 3: Start of Weaving\nNow we thread a long thread into the needle. At the end of the thread we fix the thread with a knot. We place it from the side of the extreme warp thread.\nAccording to the drawing scheme, we collect the required number of beads on the needle for the first row of weaving, move them to the knot and press them under the stretched warp threads from below so that each bead falls between two threads.\nWe unfold the needle and pass it through all the beads so that the needle passes over the warp threads.", "673" ], [ "Now tighten the thread, but not too tight.\nThus, two threads, below and above, will hold the beads on the warp threads. Fastening the first row is the most difficult moment in loom weaving. When you have completed the first row, align all the beads in a horizontal line.\nThen string on the beads for the second row. Pass it under the warp threads from below. Press the beads into the gaps between the strands.\nPass the needle through the beads in the opposite direction over the warp threads. In the same way, weave to the end.\nStep 4: Pattern Formation Process\nAfter a while, you can observe the formation of a bead pattern according to the original pattern.\nStep 5: Removing the Bracelet From the Loom\nAfter you have finished weaving a beaded bracelet, you need to remove it from the loom. From each end of the bracelet, cut all the threads.\nThen every two threads in turn need to be knitted with several knots and cut off.\nStep 6: Clasp Installation\nWhen we finished the bracelet at the ends on both sides, you need to install clasps.\nStep 7: The Result of the Work Done\nThen you can enjoy the finished result. This jewelry will delight you and your family ones!\nThank you all for watching and reading the article. Don’t forget to like it and subscribe!", "748" ], [ "DIY Tabletop Easel and Wall Decor From Cardboard\nIntroduction: DIY Tabletop Easel and Wall Decor From Cardboard\nWhen making a paper quilling project, I often feel uncomfortable and back pain that may be caused by my flat table. I think I should get an easel to get my posture right, but the easel on market are quite pricey for me. So I decided to make my own easel from cardboard, it's easy to make, low cost, and multifunction (I used it as a wall decoration as well to save some space).\nSupplies\n1. cardboard\n2. cutter\n3. scissors\n4. hot glue/super glue\n5. vinyl sticker (for decoration)\n6. 2 (two) sticks (wooden stick or cut from a plastic hanger)\nStep 1: Mainboard\nI make the mainboard in the size of 32 x 27 x 5.5 cm and because my cardboard is quite thin, I double the board. Then use tape to connect the edges. Make 4 holes for the easel's legs on the edge as you can see in the picture.\nStep 2: Easel's Upper Legs\nI cut the cardboard in the size of 30x2.5 cm for the upper leg, and make it double.", "294" ], [ "I covered the leg with brown shipping tape to make them neater and don't forget to make some holes on the legs.\nPrepare a wooden stick or stick from the hanger, insert it to the hole in the mainboard and insert the upper leg as you can see in the picture. Glue the stick on the outer part of the mainboard to make it stay in place (use hot glue and super glue). Give some space between the side of the mainboard and the upper leg (space is for the lower legs). Cut some short strips of cardboard and glue them to the stick to make the upper leg stay in place.\nInsert another stick to the lower hole of the legs (no need to glue or secure this stick).\nStep 3: Easel's Lower Legs\nI cut the cardboard in the size of 27x2.5 cm for the lower leg, and make it double. I also covered them with brown shipping tape.\nCut two short sticks from wooden/plastic hanger, insert them into the lower hole of the mainboard. Glue the stick on the outer part of the mainboard to make it stay in place (use hot glue and super glue). Attach the lower leg to the stick and secure them by gluing a little piece of cardboard to the tip of the short stick.\nnow the easel is almost ready. When you want to use it, insert the stick of the upper leg into the free hole of the lower legs.\nStep 4: Decorating the Easel\nAs I mention before, I want to make this easel as a wall decoration as well, so I need to make it looks pretty. So I decided to print a design on a vinyl sticker and apply it on a duplex board (the surface of the cardboard that I used is quite wrinkly and might affect the appearance of the vinyl sticker)\nCut some rectangles from the cardboard and stack them together to make the barrier of the easel (red mark on the 4th picture). Glue it on the mainboard, and then glue the decorative duplex board above it. I used a super glue to make sure they are strongly attached to the mainboard.\nStep 5: Hang the Tabletop Easel\nNow you have your own tabletop easel that you can turn into a wall decoration! Honestly it's such a space saver, I don't need to make space to store the easel, I just need to hang it on my wall. Super easy!\nIf you also make this project, let me know! :D", "959" ], [ "How to Make MINI PAPER CUP ?\nIntroduction: How to Make MINI PAPER CUP ?\nHow to make MINI PAPER CUP?\nA mini paper cup is a good option for joint creativity for children and parents. In children, the process of making a mini paper cup develops creativity, artistic taste, and fine motor skills. And the production time will take no more than 30 minutes.\nWatch a video on how to make mini paper cup\nMaterials and tools for making mini paper cup:\n● A sheet of colored paper;\n● Felt-tip pen;\n● Scissors;\n● Glue stick.\nSupplies\nВзаимодействие с другими людьми\nStep 1:\nВырежьте из цветной бумаги квадрат размером 15 на 15 см. Взаимодействие с другими людьми.\nStep 2:\nFold the sheet in half back (away from yourself) so\nthat one part is flat against the other.\nStep 3:\nFlatten the sheet. As a result, a fold line should remain. Fold the bottom side to the fold line.\nStep 4:\nFold the top side to the fold line.\nStep 5:\nFold the right side to the left to form a square.\nThis should leave a center fold line. Turn the square with the fold line towards you.\nStep 6:\nBend the square towards you.", "163" ], [ "Fold the bottom of the rectangle to the center fold and flatten, fold the top of the rectangle to the center fold and flatten. As a result, there should be 2 more fold lines.\nStep 7:\nFold the bottom of the rectangle towards the top fold line and flatten. Fold the top side of the rectangle towards the bottom fold line and flatten. After that, 5 fold lines were obtained. Bend the bottom side of the rectangle again to the bottom fold line, and the top side of the rectangle to the top fold line and flatten. As a result, 7 fold lines should remain.\nPeel back the right side of the rectangle and cut it.\nStep 8:\nRotate the resulting rectangle horizontally away from you.\nStep 9:\nMake cuts along the 7 bottom vertical folds (up to the horizontal fold line).\nStep 10:\nCut off the last detail.\nStep 11:\nTurn the model over. Draw the eyes.\nStep 12:\nDraw the mouth and cheeks.\nStep 13:\nApply glue to the far right side of the craft.\nStep 14:\nGlue the extreme edges together.\nStep 15:\nTo make the bottom of the mini paper cup , fold and glue the protruding ponytails.\nStep 16:\nIt turned out the bottom of the mini paper cup.\nStep 17:\nCut out a 5 cm by 3 cm rectangle from the remains of colored paper - this will be a pen.\nStep 18:\nBend it in half along the long side and glue it.\nStep 19:\nBend the resulting rectangle in half again and glue it again.\nStep 20:\nBend one edge of the handle.\nStep 21:\nBend the second edge of the handle.\nStep 22:\nApply glue to these parts and glue to the mini paper cup.\nStep 23:\nThe mini paper cup is ready !!!", "636" ], [ "Paper Lotus Flower\nIntroduction: Paper Lotus Flower\nGood afternoon, dear viewers and readers! In today's instruction, I will show you how to make a DIY paper lotus flower.\nSupplies\nTo create a lotus flower out of paper, we need:\n* Coloured paper.\nEssential Equipment:\n* Scissors.\n* Ruler.\n* Pencil.\n* PVA glue stick.\nStep 1: Cutting Paper Into Pieces\nFirst you need to mark the paper with a ruler and a pencil. From a sheet of A4 paper, we need to get 6 squares with dimensions of 9 cm by 9 cm, we will need the remaining strips after cutting out to complete the formation of a lotus flower.\nIn total, we need 8 pink squares and 8 green squares.\nStep 2: Fold the Sheet in Half\nNext, proceed to the formation of a lotus flower. Take a square piece of paper and fold it in half. Then fold the sides in half again.\nStep 3: Corner Bending\nThen we spread the sheet of paper so that we get a rectangle. After we begin to bend the corners in the form of triangles, first on the side where there is a solid fold.\nThen we need to fold the corners on the side where there is no solid paper seam. Next, we bend this part of the paper and turn the blank over to the other side and bend the corners. We should get a blank in the form of a boat.\nStep 4: Petal Formation\nThen the sides of the resulting shape need to be moved apart and one edge bent inward. In this way we get a flower petal.\nStep 5: Flower Formation\nNext, we need to insert the resulting petals into each other. Previously, the sides of the petals must be greased with glue stick for better retention.\nStep 6: Preparing the Bottom\nNext, on the green square, you need to step back 3 cm from the side and make a mark. Then we need to bend the sides so that we get three identical folds.\nStep 7: Folding Corners at the Bottom\nThen on each side you need to bend the edges to the middle.", "6" ], [ "Then all once again you need to bend exactly in the middle.\nThen we need to fold the corners on the side where there is no solid paper seam. Next, we bend the other part of the paper and turn the blank over to the other side and bend the corners again. We should get a blank in the form of a boat as described before.\nStep 8: Bottom Formation\nNext, the resulting parts must be inserted into each other and glued as in the first case.\nStep 9: Preparation of a Long Strip\nNext, prepare the middle part. We will use the remaining strips 3 cm wide and about 60 cm long. On the blanks along the length, you need to make many small cuts in the form of small strips. Then everything needs to be twisted into a tube and glued on the edges.\nStep 10: Gluing Parts\nThen we begin to glue all the details together. Glue the lotus flower to the bottom first. Then we glue the part in the form of a fleecy tube in the middle of the flower.\nStep 11: Finished Result\nThen you can enjoy the finished result. This paper lotus flower will delight you and your loved ones!\nThank you all for watching and reading the article. Don’t forget to like it and subscribe!", "6" ] ]

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[ [ "1. what are the rows before the first red row? I thought it may be the combinations of parameters but that doesn't make a lot of sense because those are not enough\nParameters, which are the candidates of the CV are printed\n2. What is the meaning of the row between the red rows? Why those parameters are there? is this after one CV?\nIt is printed after the completion of the 3rd(as defined in your code) fold for a parameter Candidate\n3. \"Done one task\" - what is the task? one CV?\nThis is from the joblib I believe. It's the completion of one fold i.e. one out of 36.\n4. Why do I get a score only for some of the parameters?\nThe score is printed after the completion of 3(as defined in your code) fold of each parameter candidate\nIn a multi-thread setup, we can't rely on the sequence of the messages as it will depend on the Thread allocation.\nMy answer is based on this small setup. ```python from sklearn.datasets import load_iris from sklearn.linear_model import LogisticRegression from sklearn.model_selection import RandomizedSearchCV iris = load_iris() logistic = LogisticRegression(solver='saga', tol=1e-2, random_state=0)\ndistributions = dict(C=[0.1,0.5,1.0], penalty=['l2', 'l1'], max_iter=[50,100]) clf = RandomizedSearchCV(logistic, distributions, random_state=0,n_iter = 5, cv = 2, verbose=10)\nfrom joblib import Parallel, delayed, parallel_backend with parallel_backend('threading',n_jobs=12): search = clf.fit(iris.data, iris.target) ```\nOutput\nFitting 2 folds for each of 5 candidates, totalling 10 fits\n[CV] penalty=l2, max_iter=100, C=0.5 .................................\n[CV] penalty=l2, max_iter=100, C=0.5 .................................\n[CV] penalty=l1, max_iter=100, C=1.0 .................................\n[CV] penalty=l1, max_iter=100, C=1.0 .................................\n[CV] penalty=l2, max_iter=50, C=0.5 ..................................\n[CV] penalty=l2, max_iter=50, C=0.5 ..................................\n[CV] penalty=l2, max_iter=100, C=1.0 .................................\n[CV] penalty=l2, max_iter=100, C=1.0 .................................\n[CV] penalty=l2, max_iter=100, C=0.1 .................................\n[CV] penalty=l2, max_iter=100, C=0.1 .................................\n[CV] ..... penalty=l2, max_iter=100, C=1.0, score=0.960, total= 0.0s\n[CV] .....", "392" ], [ "penalty=l2, max_iter=100, C=0.5, score=0.973, total= 0.0s\n[CV] ..... penalty=l2, max_iter=100, C=0.1, score=0.947, total= 0.0s\n[CV] ..... penalty=l1, max_iter=100, C=1.0, score=0.973, total= 0.0s\n[CV] ..... penalty=l2, max_iter=100, C=1.0, score=0.973, total= 0.0s\n[CV] ...... penalty=l2, max_iter=50, C=0.5, score=0.973, total= 0.0s\n[CV] ..... penalty=l2, max_iter=100, C=0.1, score=0.893, total= 0.0s\n[CV] ..... penalty=l2, max_iter=100, C=0.5, score=0.960, total= 0.0s\n[CV] ...... penalty=l2, max_iter=50, C=0.5, score=0.960, total= 0.0s\n[CV] ..... penalty=l1, max_iter=100, C=1.0, score=0.987, total= 0.", "60" ], [ "Why are the regions/decision boundaries overlapping with multi-class classification using SVM in sci-kit?\nI am using the SVM in scikit-learn library for doing multiclass classification. I am wondering why these regions (decision boundaries) are overlapping (as seen in the picture below)?\nCould someone please explain the difference between whether I do one-vs-one or one-vs-all in terms of the regions overlapping? I assumed one-vs-one would have clearly delineated regions with no overlap since it's maximizing the margin against each other class and that one-vs-all could have regions overlapping, but perhaps this is inaccurate because 3 of the 4 models I am training are one-vs-one, and they show overlapping regions.\nI've considered maybe it's a plotting issue as well, but could not determine any issues.", "392" ], [ "If the alpha is 1, then the regions no longer overlap, but I assume this is expected since it's just covering up the other regions it overlays (which is to be expected and doesn't solve the problem).\nHere is the function which creates, trains, and plots 4 different SVM models #(3 different kernels using SVC and 1 with LinearSVC).\ndef createSVMandPlot(X,y,x_name,y_name):\nh = .02 # step size in the mesh\n# we create an instance of SVM and fit out data. We do not scale our\n# data since we want to plot the support vectors\nC = 1.0 # SVM regularization parameter\nsvc = svm.SVC(kernel='linear', C=C).fit(X, y) #1 vs 1\nrbf_svc = svm.SVC(kernel='rbf', gamma='scale', C=C).fit(X, y) #1v1\npoly_svc = svm.SVC(kernel='poly', degree=3, gamma='scale',C=C).fit(X, y) #1v1\nlin_svc = svm.LinearSVC(C=C).fit(X, y) #1 vs rest\nprint(str(x_name)+' vs. '+str(y_name))\nfor i, clf in enumerate((svc, lin_svc, rbf_svc, poly_svc)):\nX_pred=clf.predict(X)\nX_pred1=np.asarray(X_pred).reshape(len(X_pred),1)\nA=confusion_matrix(X_pred1, y)\nprint(A)\nc=0\nfor r in range(len(X_pred)):\nif X_pred[r]==y[r]:\nc+=1\nprint(str(c)+' out of 34 predicted correctly (true positives)')\n=============================================================================\nwith warnings.catch_warnings():\nwarnings.filterwarnings(\"ignore\")\n=============================================================================\nx_min, x_max = X[:, 0].min() - 1, X[:, 0].max() + 1\ny_min, y_max = X[:, 1].min() - 1, X[:, 1].max() + 1\nxx, yy = np.meshgrid(np.arange(x_min, x_max, h),\nnp.arange(y_min, y_max, h))\n# title for the plots\ntitles = ['SVC w/ linear kernel',\n'LinearSVC (w/ linear kernel)',\n'SVM w/ RBF kernel',\n'SVM w/ poly(degree 3) kernel']\nplt.pause(7)\nfor i, clf in enumerate((svc, lin_svc, rbf_svc, poly_svc)):\n# point in the mesh [x_min, x_max]x[y_min, y_max].\nplt.subplot(2, 2, i + 1)\nplt.subplots_adjust(wspace=0.4, hspace=0.4)\nZ = clf.predict(np.c_[xx.ravel(), yy.ravel()])\n# Put the result into a color plot\nZ = Z.reshape(xx.shape)\nplt.contourf(xx, yy, Z, alpha=.5)\n# Plot also the training points\nplt.scatter(X[:, 0], X[:, 1], s=13,c=y)\nplt.xlabel(x_name)\nplt.ylabel(y_name)\nplt.", "392" ], [ "My model is predicting values ​for only two labels (instead of 9) how to fix it?\nMy goal is to predict the count (variable y) based on various features (variable x). My y is most of the time (98.4%) equal to 0, so this data is inflated by 0.\nBased on this premise, I thought that using the Zero Inflated Model with SVC could be an asset, given the characteristics of my data.\nSo I found a code on the internet and i'm trying to apply it to my problem (i'm very new to this)\nfrom sklego.meta import ZeroInflatedRegressor\nzir = ZeroInflatedRegressor(\nclassifier=SVC(),\nregressor=LinearRegression()\n)\nzir.fit(scaled_train, y_train.values.ravel())\npredictions = zir.predict(scaled_test)\nI believe my problem is exactly in this part of the code below, where I am appending only 0s and 1s. However, how do I make predictions for the other counts? This is what I'm not able to understand.\ntrashold = .5\npreds =[]\nfor val in predictions:\nif val>trashold:\npreds.append(1)\nelse:\npreds.append(0)\naccuracy_score(y_test,preds)\n0.9976208095270875\nEven in my classification_report I have an alert precisely because I don't have samples for the other labels.", "392" ], [ "How to fix such a problem?\nprint(classification_report(y_test,preds))\nPrecision and F-score are ill-defined and being set to 0.0 in labels with no predicted samples. Use `zero_division` parameter to control this behavior.\nprecision recall f1-score support\n0.0 1.00 1.00 1.00 916493\n1.0 0.86 0.97 0.91 11398\n2.0 0.00 0.00 0.00 1498\n3.0 0.00 0.00 0.00 231\n4.0 0.00 0.00 0.00 73\n5.0 0.00 0.00 0.00 22\n6.0 0.00 0.00 0.00 5\n7.0 0.00 0.00 0.00 5\n8.0 0.00 0.00 0.00 2\n9.0 0.00 0.00 0.00 1\naccuracy 1.00 929728\nmacro avg 0.19 0.20 0.19 929728\nweighted avg 1.00 1.00 1.00 929728\nTo illustrate my problem, I have the following image. Which shows that 0 values ​​are reasonably well predicted, but from 1 I don't have any predictions anymore.\nplt.clf()\nplt.hist([y_train.values, preds], log=True)\nplt.legend(('orig','pred'))\nplt.show()\nAny idea how I can improve this model and have predictions for all classes? Thank you very much in advance.", "392" ], [ "Both are within one-vs-all scheme when there is a classification task.\nLabelBinarizer it turn every variable into binary within a matrix where that variable is indicated as a column. In other words, it will turn a list into a matrix, where the number of columns in the target matrix is exactly as many as unique value in the input set. If your input labels look like [1, 4, 5] the resulting matrix, is a 3 column matrix and each 1, 4, 5 are a column. then if your instances (observations) are either of 1,4,5, it is gonna be indicated (binary) whether that instance correspond to label 1 or 4 or 5.\nyou use LabelBinarizer to build regular classifier, for example to train a logistic regression and create the response variable you can use\nfrom sklearn.preprocessing import LabelBinarizer\nlb = LabelBinarizer()\nlb.fit_transform(['yes', 'no', 'no', 'yes'])\nthe output is\narray([[1],\n[0],\n[0],\n[1]])\nor if your feature column is ['red', 'red', 'green', 'blue', 'blue']\narray([[1, 0, 0],\n[1, 0, 0],\n[0, 1, 0],\n[0, 0, 1],\n[0, 0, 1]])\nMultiLabelBinarizer - does the similar thing but when you have multiple lables.", "392" ], [ "when do you have multiple labels ? for example when you are doing mu multiple label classification. Say, you are building a classifier to predict tags for Questions on StackoverFlow. Your data looks like this\nqId Tag\n0 1 c#\n1 2 python\n2 2 machine_learning\n3 2 pandas\n4 2 nlp\nbut you have to convert it in a format where you can do machine learning (one row per observation)\n| qId | c# | python | machine_learning | pandas | nlp | |----|------|--------|------------------|--------|-----| | 1 | 1 | 0 | 0 | 0 | 0 | | 2 | 0 | 1 | 1 | 1 | 1 |\nand you will use\nimport pandas as pd\nfrom sklearn.preprocessing import MultiLabelBinarizer\nquestion_tags = pd.read_csv(\"question_tags.csv\")\nprint(question_tags.head())\nmlb = MultiLabelBinarizer()\nprint(mlb.fit_transform(question_tags))\nI hope this clear out the differences when it comes to the practice\nUPDATE on your case\nhow do you parse your 15K unique role to get those 3 category or combination ? is it like, seniority, department, role ? if so, shouldn't you make it like\nquestion_tags = [{'Senior', 'Android', 'Engineer'}, {'Senior', 'Asset', 'Manager'}, {'Senior', 'Billing', 'Manager'}]\nand then pass it to the\nmlb = MultiLabelBinarizer()\nres = pd.DataFrame(mlb.fit_transform(question_tags), columns=mlb.classes_)\nand you will end up with\nwhich shows all three are senior, number 2 and 3 are managers and so on ?\nUPDATE 2\nif you don't have it parse and basically just need to encode each of 15K unique label, you go with binary. For example you have four observation where two of them are senior android engieers.\nquestion_tags = ['Senior Android Engineer','Senior Android Engineer', 'Senior Asset Manager', 'Senior Billing Manager']\nlb = LabelBinarizer()\npd.DataFrame(lb.fit_transform(question_tags), columns = lb.classes_)", "422" ], [ "We don't use Pipeline so we needed to just save the OneHotEncoder state for use in a different process. pickle is frowned up due to security and backward compatibility issues and hence by extension joblib is frowned upon, too. To be more precise, we were hoping to find a better/different way to save the encoder state from training and use it during scoring later. We ended up doing the following:\n1. Fit/transform during training as usual\n2. Harvest the ordered categories from the training-time encoder and save it as json/yaml.\n3. During production run, read the ordered categories and use those to hydrate a new encoded. It needs a bit of kick to get going (see example below).\n4.", "242" ], [ "The kicker is that it allows us to alter the behavior of the encoder during production, e.g. make it resilient to hitherto unknown categories.\nFollowing is an example code to demonstrate the approach:\nimport pandas as pd\nimport numpy as np\nfrom sklearn.preprocessing import OneHotEncoder\nds = pd.DataFrame(\n{\n\"colors\": [\"red\", \"red\", \"white\", \"blue\"],\n\"fruits\": [\"apple\", \"orange\", \"apple\", \"orange\"],\n}\n)\nThis is our sample dataset\ncolors fruits\n0 red apple\n1 red orange\n2 white apple\n3 blue orange\nLet's encode the data:\nencoder_training = OneHotEncoder(sparse=False)\nencoded_colors = encoder_training.fit_transform(np.array(ds.colors).reshape(-1, 1))\nencoded_colors\nThe encoding is as follows:\narray([[0., 1., 0.],\n[0., 1., 0.],\n[0., 0., 1.],\n[1., 0., 0.]])\nAs expected this one isn't tolerant to unknown categories.\nencoder_training.transform(np.array(\"black\").reshape(-1, 1))\nThis will give the following error.\nValueError: Found unknown categories ['black'] in column 0 during transform\nAfter the fit, however, the encoder contains ordered list of categories that were used by the encoded to generate the encoding (and hence that are being used by the model)\ncolor_categories = encoder_training.categories_\nHere are its contents\ncolor_categories\n[array(['blue', 'red', 'white'], dtype=object)]\nNow let's create another encoded for production/scoring. Note, however, that this one needs to have a different behavior for handling unknown values. Why? Because often the needs (and some times even the people responsible) for production might be different from that doing training. For example, if encoder is run on the entire training dataset including the test/holdout set then it would never have to deal with unknown categories.\nencoder_production = OneHotEncoder(\nhandle_unknown=\"ignore\", sparse=False, categories=color_categories\n)\nWe have supplied it the ordered categories array that we had harvested from the training encoder. In practice this would be serialized as json/yaml during training and be loaded back in the production python process. Note: I'm using sparse=False only to make it easy to see the encoding in the example.\nOddly, though, we can't use this directly, first we need to bootstrap it! This can be anything. To avoid any type mismatch issues we simply use the 1st item from the categories list\nencoder_production.fit(np.array(color_categories[0][0]).reshape(-1, 1))\nNow our encoder it's ready for prime time!\nencoder_production.transform(np.array(\"red\").reshape(-1, 1))\nThis prints:\narray([[0., 1., 0.]])\nUnlike the training instance, this one is tolerant to unknown values\nencoder_production.transform(np.array(\"black\").reshape(-1, 1))\nThis prints:\narray([[0., 0., 0.]])", "422" ], [ "I think there are several points to take into account:\n* First, it is possible that, in this case, the default XGBoost hyperparameters are a better combination that the ones your are passing through your params__grid combinations, you could check for it\n* Although it does not explain your case, keep in mind that the best_score given by the GridSearchCV object is the Mean cross-validated score of the best_estimator (source), it is, the mean test score across the k trainings over the k-folds, so it can maybe give you a more reliable score value (including also the standard deviation of the k scores)\nConsider also that you do not need to retrain your model with the best params fron the grid search CV, since you can access the best model via search.best_model\nLastly, I would also recommend other hyperparameter tuning methods like the bayesian tuning, below a sample code gist using hyperopt (info about bayesian optimization here):\nfrom hyperopt import hp\nfrom sklearn.model_selection import StratifiedKFold\nfrom hyperopt import fmin, tpe, hp, STATUS_OK, Trials\nfrom sklearn.model_selection import cross_val_score\ndef return_model_scores(params, dataX, dataY, n_folds=5):\nimport numpy as np\ndefined_model, edp_cost_scores, histories =\nevaluate_model_cost(dataX = dataX, dataY = dataY)\nreturn np.array(edp_cost_scores).mean()\nparam_space = {'max_depth' : hp.choice('max_depth', range(5, 30, 1)),\n'learning_rate' : hp.quniform('learning_rate', 0.01, 0.5, 0.01),\n'n_estimators' : hp.choice('n_estimators', range(20, 205, 5)),\n'gamma' : hp.quniform('gamma', 0, 0.50, 0.01),\n'min_child_weight' : hp.quniform('min_child_weight', 1, 10, 1),\n'subsample' : hp.quniform('subsample', 0.1, 1, 0.01),\n'colsample_bytree' : hp.quniform('colsample_bytree', 0.1, 1.0, 0.01),\n'scale_pos_weight': hp.uniform('scale_pos_weight', 0.2, 0.8)}\n# Some variable\ndataX = X_train\ndataY = y_train\nassert len(X_train)==len(y_train)\nn_folds=5\nglobal best # global variable defined for convenience of this use case\nbest = 0\ni = 0\ndef f(params):\ncost = return_model_scores(params, dataX, dataY, n_folds=5)\nif i == 0:\nbest = cost\nif cost < best:\nbest = cost\nprint('new best:', best, params)\nreturn {'loss': cost, 'status': STATUS_OK}\ntrials = Trials()\nbest = fmin(f, param_space, algo=tpe.suggest, max_evals=10, trials=trials)\nprint ('best:')\nprint (best)\nwhere evaluate_model_cost is the function you build for getting the cost values after evaluation:\ndef evaluate_model_cost(dataX, dataY):\nfrom tqdm import tqdm\nfrom sklearn.model_selection import KFold\nscores, histories = list(), list()\n# prepare cross validation\nkfold = KFold(10, shuffle=True, random_state=1)\n# enumerate splits\nk = 0\nfor train_ix, test_ix in tqdm(kfold.split(dataX)):\nprint('kfold {}'.format(k))\n# select rows for train and test\ntrainX, trainY, testX, testY = dataX.iloc[train_ix],\ndataY.iloc[train_ix], dataX.iloc[test_ix], dataY.iloc[test_ix]\n# fit model\nhistory = defined_model.fit(trainX, trainY,\neval_metric= 'auc',\neval_set=[(testX, testY)])\n# evaluate model\ny_preds = defined_model.", "392" ], [ "Multiclass ROC Curve using DecisionTreeClassifier\nI built a DecisionTreeClassifier with custom parameters to try to understand what happens modifying them and how the final model classifies the instances of the iris dataset. Now My task is to create a ROC curve taking by turn each classes as positive (this means I need to create 3 curves in my final graph).", "506" ], [ "To do this I need to instantiate a OnevsRestClassifier and passing the previous classifier as parameter, so it automatically recognize the parameters I modified (such as the weights of the class). This is my current code:\nfrom sklearn.datasets import load_iris\nfrom sklearn.metrics import accuracy_score\nfrom sklearn.metrics import f1_score\nfrom sklearn.metrics import roc_curve, auc\nfrom sklearn.model_selection import cross_val_score\nfrom sklearn.preprocessing import label_binarize\nfrom sklearn.model_selection import train_test_split\nfrom sklearn import tree\nfrom sklearn.multiclass import OneVsRestClassifier\nfrom sklearn.metrics import roc_auc_score\nfrom sklearn.metrics import confusion_matrix\nimport numpy as np\nimport graphviz\niris = load_iris()\nX = iris.data\ny = iris.target\n# Binarize the output\ny = label_binarize(y, classes=[0, 1, 2])\nn_classes = y.shape[1]\n# My DecisionTreeClassifier\nclf = tree.DecisionTreeClassifier(criterion=\"entropy\",random_state=300,min_samples_leaf=5,\nclass_weight={0:1,1:10,2:10})\nnp.random.seed(0)\nindices = np.random.permutation(len(iris.data))\nindices_training=indices[:-10]\nindices_test=indices[-10:]\niris_X_train = iris.data[indices_training]\niris_y_train = iris.target[indices_training]\niris_X_test = iris.data[indices_test]\niris_y_test = iris.target[indices_test]\n# Training\nclf = clf.fit(iris_X_train, iris_y_train)\n# Test\npredicted_y_test = clf.predict(iris_X_test)\nprint(confusion_matrix(iris_y_test, predicted_y_test))\nprint(\"Predictions:\")\nprint(predicted_y_test)\nprint(\"True classes:\")\nprint(iris_y_test)\n# Learn to predict each class against the other\nclassifier = OneVsRestClassifier(clf)\n# Train\nclassifier = classifier.fit(iris_X_train, iris_y_train)\n# Test\ny_score = classifier.predict_proba(iris_X_test)\n# Compute ROC curve and ROC area for each class\nfpr = dict()\ntpr = dict()\nroc_auc = dict()\nfor i in range(n_classes):\nfpr[i], tpr[i], _ = roc_curve(iris_y_test, y_score)\nroc_auc[i] = auc(fpr[i], tpr[i])\nMy problem is that I get the error:\nClass label 2 not present.\nAt the line: classifier = classifier.fit(iris_X_train, iris_y_train)\nThis is when I train the new classifier and I do not understand why. I checked on the iris dataset and there are three classes, so the label 2 should correspond to virginica, right?", "422" ], [ "Cross Validation of Random Forest results in two different score based on when the test set is created\nI have a dataset where I dont have label for 70% of data. So, my target is to train a model on 30% data that has label and then apply this model to get the label for the rest 70% of data. But, it is highly imbalanced and no single model performs well on this.", "392" ], [ "So, I took the following approach :\nMethod 1 ````python missing_df = df[df.label.isna()] nomissing_df = df[~df.label.isna()]\nsplit the labeled dataset into 80-20 parts for train and validation\n...... = train_test_split(nomissing_df)\nwhile new samples are added : #train a 5 Fold Random Forest on the train set clf = RandomForest(....) # code for training\n#evaluate the missing data label = clf.predict_proba(missing_df)\nif label > 0.75 for all fold : add to positive training samples if label < 0.25 for all fold : add to negative training samples\n**Method 2**python missing_df = df[df.label.isna()] nomissing_df = df[~df.label.isna()]\nNOOOOOOOOOOOOOOOOOOOOOOOO SPLIT HERE\nwhile new samples are added : #train a 5 Fold Random Forest on the train set clf = RandomForest(....) # code for training\n#evaluate the missing data label = clf.predict_proba(missing_df)\nif label > 0.75 for all fold : add to positive training samples if label < 0.25 for all fold : add to negative training samples\nsplit the full label dataset ( original + by the above process)\n...... = train_test_split(final_train_df)\ntrain final model\nclf = RandomForest().train(....)\nevaluate on validation set\n```` Result\nAs our dataset is highly skewed, I used precision as my evaluation metric. For method 1, training precision is around 80% but when evaluated at the held-out validation set (at the beginning), the score is 33%.\nBut for method 2, the precision score for both train and validation is 80%.\nMy question is why is a discrepancy in validation accuracy? Is method 2 is wrong or any chance of data leakage here? Or any suggestion to improve the precision of method 1 as I think method 1 more correct way to do this? Finally, is this approach of labeling data is correct or there is any other way to do this better?", "392" ] ]

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[ [ "What changed for the Macedonian people after the country changed its name to Republic of North Macedonia · Global Voices\nThe ceremony of raising the NATO flag in front of the Government of the Republic of North Macedonia on February 12, 2019. In the background: The old name of the institution was removed from the facade a day before. Photo by the Government of the Republic of North Macedonia, public domain.\nOn January 11, 2019, the parliament of North Macedonia approved the constitutional amendments that changed the country's name to Republic of North Macedonia, at last ending a 27-year-old dispute with Greece, which has its own region called Macedonia.\nThe amendment enshrined in national law the UN-brokered Prespa Agreement, signed in June 2018 between Greece's Prime Minister <PERSON> and his Macedonian counterpart <PERSON>. They were both nominated to this year's Nobel Peace Prize for ending one of the oldest active ‘cold’ conflicts in Europe.\nThe change was a crucial step on the Republic of North Macedonia's path towards joining the European Union and NATO, as that had been vetoed beforehand by Greece because of the name issue.\nHowever, that didn't just transform the Balkan country's international relations: it also introduced many changes that affect the everyday lives of its people.\nThe names of government bodies, websites, road signs, and inscriptions on public buildings have either been replaced, or are slated to be replaced, since the new name became official on February 12.\nSymbolically, the road sign on the Greek border was the first to be amended with the new name. Some others will incur in significant costs and are still pending. That includes the plaque on the government's main building.", "739" ], [ "The original sign, with the words “Government of Republic of Macedonia,” was removed on February 11 and a new one hasn't yet arrived.\nFor citizens on both sides of the border, one benefit of improved neighborly relations is the reinstatement of a flight connection between Skopje and Athens after more than ten years. The flight began on November 1, 2018.\nBefore: On February 10, the government seat's building displayed the words “Government of Republic of Macedonia,” in Macedonian Cyrillic. They were removed the next day to be replaced with the new constitutional name of the country. Photo by Global Voices, CC-BY\nChange of personal documents and car stickers\nThe Prespa Agreement stipulates that the personal documents of the citizens of the Republic of North Macedonia will be changed over the next five years.\nDocuments such as passports, ID cards, or car license plates, will be valid over this period, and replacement will be gradual. Citizens whose documents bearing the old name expire before that deadline will get new ones, with the new name, whenever they renew them.\nMeanwhile, the police officers on all border crossings started adding a stamp onto Macedonian passports that says: “This passport is the property of Republic of North Macedonia.” This is a temporary measure while passports with the old name are still valid.\nNorth Macedonia's codes for license plates will also change from MK to NM or NMK, and border authorities have started putting “NMK” stickers on plates over the old MK field.\nOne concession made by the Prespa agreement is the country's code for purposes other than license plates, like the top level internet domain, which will remain MK and MKD, as officially assigned by the International Organization for Standardization (ISO).\nThe inside front cover of a Macedonian passport with a stamp designating the new name of the country in three languages (Macedonian, English, and French). Underneath it, a now-obsolete sheet that Greek authorities used to stamp entry and exit of Macedonian visitors in place of their passports. Photo by Global Voices, CC-BY\nChanges in Greece\nGreece has also introduced a few changes since the agreement's signature, including recognizing North Macedonia's passports.\nUntil February 2019, Macedonian visitors in Greece had to fill in a separate piece of paper in Greek and English which served as a kind of surrogate passport — a document that border police would stamp so that they didn't have to deal with passports bearing the name “Republic of Macedonia.” While on Greek soil, travelers had to keep that piece of paper with them at all times.\nSince the Prespa agreement, Greek authorities have also stopped putting stickers on the cars of Macedonian citizens entering Greece that read, in Greek and English, that the country was “recognized by Greece as FYROM.” The acronym stands for “former Yugoslav Republic of Macedonia,” which was how the UN referred to North Macedonia since the 1990s while a solution to the dispute was pending.\nIn 2012, this was considered a humiliating provocation by Macedonian authorities, as well as by Macedonian tourists visiting Greece who saw it as unnecessary political harassment while they put money into the Greek economy.\nNothing changed for the Greek citizens traveling to North Macedonia.", "363" ], [ "Serbian nationalists want to build an extravagant Triumphal Arch in a Belgrade park · Global Voices\nThe Triumphal Arc in Skopje, North Macedonia, in December 2019. Photo by Global Voices, CC-BY.\nThe nationalist political party Serbian Renewal Movement (SPO), a member of the ruling coalition in Serbia, is pushing for the construction of a massive Triumphal Arch in the center of Belgrade to commemorate military victories achieved in the Balkan Wars and the First World War. The arch would be flanked by statues of King <PERSON> and King <PERSON> of Serbia.\nSerbia's ruling Serbian Progressive Party (SNS), lead by President <PERSON>, has launched other controversial (and costly) urban projects since it came to power in 2012. Those including the Belgrade Waterfront, a musical fountain, a giant flag pole, and a cable-car in the Belgrade Fortress — the latter has been recently put on pause by a court ruling.\nThe SNS enjoys the support of the SPO, a small right-wing party that used to be influential in the 1990s — it even had its own paramilitary wing, the Serbian Guard — but that has since shrunk in size and importance. Writing for Serbian newspaper Danas, political analyst <PERSON> said that the Triumphal Arch proposal was “a way for them to show they still exist.”\nThe SPO proposal, put forward in the Belgrade City Assembly on December 6 without a cost estimate or a funding plan, drew comparisons with similar architectural shenanigans by authoritarian regimes in the Balkans.\nIn neighboring North Macedonia, the “Skopje 2014” project erected over 130 neoclassical structures — among them monuments, statues, government buildings, and museums — in the capital to the cost of at least 763 million USD between 2010 and 2014.", "739" ], [ "The single most expensive structure was a Triumphal Arc called Porta Macedonia, which came to over 7 million dollars. The entire initiative was marred by corruption benefiting cronies of <PERSON> VMRO-DPNME party, who ruled North Macedonia from 2006 to 2017.\nBoth SNS and VMRO-DPNME are members of the conservative European People's Party and have cultivated a strong bilateral cooperation at that time when VMRO was in power in North Macedonia. The two populist regimes have often been implicated in backsliding of democracy and degradation of human rights standards in their respective countries.\nA 2011 cartoon picturing <PERSON>, former Macedonian PM who built a Triumphal Arc in Skopje. Cartoon by <PERSON> AKA Dar-Mar, via Citizens for European Macedonia. Used with permission.\nIn a statement, the SPO argues that Serbia needs such “monumental memorial” in order to “remind us of the glorious moments of our history, inspiring present and future generations to love and defend their homeland.” Party Vice President <PERSON> said:\nПредлажемо да Тријумфална капија буде подигнута у некадашњем Краљевом, данас Пионирском парку између здања Скупштине Србије и Новог двора, односно садашњег Председништва.", "260" ], [ "North Macedonia’s <PERSON>, the prime minister who ‘has done the most to serve his country’ · Global Voices\n<PERSON> leaving the official building of the government of the Republic of North Macedonia. Photo by Government of Republic of North Macedonia, Public Domain.\nAfter having announced his decision on October 31, <PERSON> submitted his resignation as North Macedonia’s prime minister on December 22, thus triggering the constitutional procedures for the resignation of the prime minister and government, and assignment of the mandate to form a new government. A day later, the parliament confirmed his resignation at a plenary session.\nIn the text of his resignation published on the government website, <PERSON> noted he undertook this “logical step” as a way to “accept responsibility” for his party's poor results at the local elections in October. He also resigned as leader of the ruling party, announcing his retirement from politics. After <PERSON>'s resignation, President <PERSON> gave the mandate to the new representative of the established parliamentary majority to form a government.\nWhile we are looking at the constitutional procedures and assessing the leadership of <PERSON>, it is worthwhile mentioning that he is the first prime minister in the history of North Macedonia to resign while his party was still in power (Actually, <PERSON>, another Social Democrat, resigned as party leader and prime minister in 2004, but this was to allow him to seek election as president of the country.)\n<PERSON> was a very interesting politician and one who had attracted the public eye. He was first elected as party leader eight years ago as a part of a team. He was the candidate for leader, while the current minister of defense, <PERSON>, was the candidate to be his deputy. The duo led the party during the political crisis of the wiretapping revelations, the negotiations of the Przhino Accords and the early parliamentary elections in 2016. <PERSON>'s election promises were to restore democracy and freedom, bring the country into NATO and the EU, and improve the quality of life of its people.\n<PERSON> and his VMRO-DPMNE had a strong hold on the government and institutions; it was an authoritarian regime that the European Commission described as a captured state.", "363" ], [ "For every citizen who had lived a day in such fear, or the nearly 20,000 whose phones were wiretapped, bringing back democracy and freedom was of utmost importance. On this, his primary promise to make North Macedonia more democratic and freer, he delivered the most.\nAfter it became clear, in January 2017, that <PERSON> was unable to form a government, his party orchestrated persecution against civil society and activists, with a long list for “execution” containing up to 170 most prominent political and civic leaders and opinion-makers. He disallowed any transfer of power and supported the storming of parliament on April 27, 2017. The angry mob attacked and beat scores of people, effectively making <PERSON> pay with his own blood to be elected as prime minister.\nHaving witnessed how <PERSON> used ethnic tensions to raise the fear of ethnic Macedonians, <PERSON> realized that this fear could only be decreased with further unification in society and if the country’s safety and security were guaranteed. The best guarantee for that was unification under the same goals as NATO and EU Accession, and genuine inter-ethnic integration, which led to the new government policy of “One Society for All.” He further supported this by speaking to all citizens and ethnic groups, presenting candidates for mayors in traditionally Albanian municipalities, while promoting politicians, Social Democrats, representing minority ethnic groups to high posts in the party and in the government. It was in many aspects a pioneering approach for North Macedonia and showed <PERSON>'s ability to see the bigger picture.\nHis political instinct as opposition leader to establish friendships and build alliances was successfully transformed into a vision to which he dedicated his first three years as prime minister, resolving the open issues of the country. It was lucky for him that this vision was met halfway by former Greek Prime Minister <PERSON>. The Prespa Accord was an effective resolution of the name issue with Greece, but it was also the foundation for North Macedonia to accede to NATO and fulfill one of its national priorities almost three decades after its independence.\n<PERSON>'s first attempt at friendship building was with Bulgaria and produced the treaty on friendship, good neighborliness and cooperation, which he signed with his Bulgarian counterpart <PERSON> on August 1, 2017. The Friendship Agreement speeded up the strengthening of bilateral relations in the period from the signing of the agreement until mid-2019 and facilitated trade, but it has yet to bear fruit, as Bulgaria is currently blocking the EU Accession of North Macedonia.\nOne final attempt at friendship building was tied to his faith and religious background.", "409" ], [ "Pope <PERSON> will visit North Macedonia in May, shortly after presidential elections · Global Voices\nScreenshot of the website papa.mk, set up by the Government of Republic of North Macedonia on occasion of the Pope's visit on 7 May 2019.\nPope <PERSON> will visit North Macedonia in May 2019, just two days after the second round of presidential elections.\nIt will be the first time a pope visits North Macedonia. The visit is part of a three-day regional tour which will also include a stop in Bulgaria.\nThe government of North Macedonia has set up a website, papa.mk to facilitate the visit. In line with the multicultural character of the country, the website contents are available in three languages: Macedonian, Albanian and English.\nSome citizens have questioned the government's ownership of the website, claiming that it contradicts the country's secular character.\nMacedonian citizens can apply for tickets to the Pontiff's Holy Mass, which are free of charge, through local churches, while foreigners must secure their places through the website. The Mass will take place at the main square of the capital Skopje on May 7.\nCatholics make up less than one percent of the population of North Macedonia, where about 65 percent have professed faith for Orthodox Christianity and about 33 percent are Muslim. Despite its small size, the local Catholic community is considerably diverse as it includes ethnic Macedonians, Albanians, Croats, Slovenes, and Poles.\nOn the other hand, the country has religious significance for Catholicism because the capital Skopje is the birthplace of Mother <PERSON> (1910-1997), officially honored as Saint Theresa of Calcutta.", "363" ], [ "One of the most popular missionaries of the 20th century, and a recipient of the Nobel Peace Prize, she was born in an ethnic Albanian family whose house was situated precisely on what is now the main town square.\nThe political aspect of the visit surpasses its religious significance. As a head of state, the pontiff is scheduled to meet the prime minister and the outgoing president, whose mandate will end five days afterward.\nThe Macedonian public appears to see the visit as a sign of recognition by the West, and a boost to the government's efforts to bring the country closer to membership of NATO and the European Union. Such sentiment is apparent in a tweet from retired police general <PERSON>, who commented on the preparatory visit by the chief of Macedonian Public Safety Bureau to the Vatican.\nБлагодарение на мудрата, храбра и одлучна меѓународна политика на оваа Влада, нашата мала држава со големи чекори оди напред!\nДиректорот на БЈБ Сашо Тасевски подготвува највисоко ниво на безбедност за престојот на Папата Франциск во Скопје.\nСтево за Претседател! pic.twitter.com/zF2m2lvzL3\n— <PERSON> (@StojanceAngelov) April 17, 2019\nThanks to the wise, brave and determined international politics of this government, our small state moves forward with great strides! The Director of PSB <PERSON> prepares the highest security level for the Pope <PERSON>’ stay in Skopje.\n<PERSON> [Pendarovski] for president!\nA month ahead of Pope's journey, Vatican News, the information system of the Holy See, added Macedonian language to its repertoire. It is the 34th language available on the portal. Skopje Bishop <PERSON> said this is “a first-fruit of Pope <PERSON>’ Apostolic Visit.”\nAhead of <PERSON> Journey to #NorthMacedonia on 7 May, @VaticanNews adds a page dedicated to the Macedonian language. https://t.", "260" ], [ "Poland’s artistic and architectural contributions remembered in 2019 commemoration of the 1963 Skopje earthquake · Global Voices\nMonument to the victims of the 1963 earthquake in Skopje. Photo by GV, CC BY.\nEvery July 26, citizens of Skopje, the capital of North Macedonia, remember the earthquake that shook the city in 1963, and express gratitude for the international action that helped rebuild the city. The 6.1-magnitude earthquake reduced much of the city to rubble, killing 1,100 people, leaving over 200,000 homeless and thousands suffering from serious injuries. At the time, Skopje was the capital of the Socialist Republic of Macedonia, a constituent state within federative Yugoslavia.\nA massive humanitarian effort to help the survivors and rebuild the city mobilized all the republics of the Yugoslav federation as well as the international community, which at the time was otherwise divided due to the Cold War. US President <PERSON> personally intervened to cut through the red tape and expedite US humanitarian aid, while USSR PM <PERSON> visited the ruined city with Yugoslav leader <PERSON>. Within days of the disaster, American and Soviet soldiers flew in to work side by side to provide humanitarian aid.\nArchitects, engineers, and construction workers from across the world worked under auspices of UN to rebuild the city into a model modernist metropolis. As a result, Skopje was nicknamed ‘the city of international solidarity.’ The UN's plan for the city was only partially implemented, but many of the brutalist-style buildings from the era remain today, and many streets still carry the names of the countries, cities or individuals who helped, including Algiers, Mexico and Prague.\nRediscovering Poland's artistic contribution\nThis year's commemoration of the earthquake is enhanced by an exhibition in Krakow, Poland that displays the artworks donated by Polish artists at the time as part of the relief effort.\nPoland was a major contributor to the disaster recovery efforts, harnessing the experience gained through the reconstruction of cities like Warsaw which were devastated during World War II. Top Polish architects helped build the iconic Museum of Modern Art, and there's still a street bearing the name of architect <PERSON>.\nAfter Ambassador <PERSON> arrived in Skopje in 2014 as Poland's highest diplomatic representative, he and his wife <PERSON> researched the Polish legacy and discovered, at Skopje's Museum of Modern Art, a unique collection of 20th-century Polish art donated by the artists after the earthquake as a gesture of solidarity. This ‘time capsule’ had been virtually forgotten in Poland. Over time, the couple uncovered many other cultural links, leading to further public discourse through exhibitions and publishing of books and other works. Some of that work is documented in the short film “Skopje. The Art of Solidarity.”\nIn an email to Global Voices, Mrs.", "739" ], [ "<PERSON> and Ambassador <PERSON> explained the drive behind their efforts that have connected countries and time periods:\n<PERSON> and <PERSON> during his tenure as Polish ambassador to Macedonia. Courtesy photo, used with permission.\nSkopje must look familiar to people who have lived or spent some time in Warsaw. Destroyed and rebuilt. The same mix of styles, a similar urban space. And, on top of that, scattered around the two cities are the “islands” of modernist architecture, which we, Poles, began to rediscover just a few years ago. Post-war architecture (after 1945) has become a fashionable topic in Poland – redefined, mainly by young people. Today, some of these buildings, until recently abandoned and neglected, are considered examples of functionality and elegance. They are receiving a second life, and with that comes their new function: cafes, galleries, centers of culture and urban activity.\nThe 1963 earthquake that destroyed Skopje moved the whole world, including Poles, whose great engagement should not be surprising. Only 18 years before WWII had ended, leaving Warsaw totally destroyed. The rebuilding of the Polish capital started immediately, with great devotion and enthusiasm.\nWe are too young to remember the emotions accompanying the gestures of solidarity shown by Poles in Skopje, but we met people who told us about it. In their memories Skopje, the city that attracted professionals from all around the world, was cosmopolitan, open and modern. And it was in that spirit that the city was created anew after the earthquake.\nWe, thanks to our Warsaw experience, have been able to find this spirit in today's Skopje.", "739" ], [ "Will a new US TV series on the ‘Macedonian teens who helped elect <PERSON>’ perpetuate a tired cliché? · Global Voices\nThe book “How we elected an American president” was sold at Skopje Book Fair in September 2020. Photo by <PERSON>, CC BY.\nThe so-called “Macedonian teenagers” who set up networks of fake news sites in the lead-up to the 2016 United States election continue to turn a profit — not so much for themselves anymore, but for producers looking to capitalize on the exaggerated trope.\nTo recap: In 2016, a group of Macedonians from the city of Veles set up various sensationalist websites that peddled disinformation catering to the tastes of <PERSON> voters, including baseless conspiracy theories. The links were marketed via social media, and their basic goal was economic: To get as many clicks as possible in order to generate ad revenue.\nWhile such networks exist around the world, the high concentration of owners of those sites in a small Macedonian city, which was first identified by Buzzfeed, attracted a lot of media attention, resulting in coverage by Channel 4, CNN, Wired, NBC, and others.\nCut to four years later, streaming platform Quibi is said to be preparing a TV series, working title “Clickbait,” that tells “the true story of a group of Macedonian teenagers who made a fortune creating fake news in the run-up to the 2016 election,” according to United States magazine Variety.\nThe series will star British actor <PERSON>, who played the lead role in the historical feature-length “Dunkirk.” He will play a “Macedonian teenage ringleader” named <PERSON>, described as “a young man desperate to escape his circumstances, who discovers that publishing fake news could be his golden ticket,” says Variety.\nActor <PERSON> attending the World Premiere of <PERSON> “Dunkirk” in London in 2017. Photo by Wikipedia user <PERSON>, CC BY-SA 4.0.\nThe series executive producers include US filmmaker <PERSON> (famous for “Cloverfield” and sequels to “Planet of the Apes”) and <PERSON> (“Boy Erased”).\nBut the idea that those fake news sites were run by kids was grossly exaggerated by Western mainstream media. In 2018, Investigative Reporting Lab Macedonia revealed that those networks were not just gigs by teenage “hackers,” but that many of them were run by adults, including a Macedonian lawyer with ties to American conservatives.\nMacedonian outlet SakamDaKazam.mk followed up on the Variety story by interviewing sources from Veles, who confirmed that a team of producers visited the town in the summer of 2019.\nOne of the people they interviewed, who did not wish to be identified, was a man who had run such a website in 2016 but was not approached by the series’ producers.", "363" ], [ "He voiced reservations to SakamDaKazam.mk that the series would provide an objective view of the events. In his opinion, the series will most likely reproduce the clichés of “boys who don't speak English, but write news, teenagers wearing worn-out sneakers forming the public opinion.”\nAccording to the SakamDaKazam.mk article, the filming of the series was taking place during the summer in Bucharest, Romania, due to similarities of the architecture.\nPrior to the series, a lesser-known commercial venture related to the <PERSON> affair was a 2019 fiction book by <PERSON>, a writer from Veles itself.\n“How we elected an American president” (Како избравме американски претседател) is a spy thriller set in Veles and its surroundings. It combines historical references about the <PERSON>, who indeed lived in the Veles area in the Middle Ages, with Nazis hiding stolen art treasures in nearby tunnels during World War II. The main plot features Russian, Israeli, and Balkan spy characters fighting over the fake news industry influencing U.S. politics.\nIn an April 2020 interview with local website Veles365, <PERSON> said he never met any of the “Veles teenagers” personally, and that they are just supporting characters in his novel. He added that the teenagers “poked the entire world in the eye… Those lads don't need to be justified, but need to be respected.” In the same interview, <PERSON> also claimed he didn't receive an award for the novel of the year for 2019 ‘due to political reasons.", "278" ], [ "A Win for Citizen Activism After UNESCO Asks Macedonia to Stop All Construction Projects on Lake Ohrid · Global Voices\nOhrid Lake swans. Photo by <PERSON>, CC-BY.\nThe latest UNESCO mission to the Ohrid region in Macedonia discovered a Natural and Cultural Heritage site threatened by increased traffic and tourism pressure, inappropriate infrastructure projects and uncoordinated urban developments. It immediately released a report requesting the Macedonian government to halt construction projects in the area.\nExisting for over 3 million years, Lake Ohrid in Macedonia is the oldest lake in the European continent holding valuable information on evolution aside from being the home of unique and rare species. In 2016, this lake was put in danger when the Macedonian government started plans to urbanize the lake shore and Galichica mountain and turn both biodiversity hotspots into mega resorts.\nCitizen activists, civil society organizations, and scientists warned about the possible catastrophic impact of these projects on Lake Ohrid and demanded a moratorium on all construction activities in the Ohrid region.\nIn March this year, the UNESCO mission to the Ohrid region validated the concerns of citizens and experts about the projects around the lake. It asked the government to halt the projects to protect Lake Ohrid and instead develop alternative ecotourism programs in the area:\nThe mission strongly recommended to completely abandon the Galičica ski centre project, keep the internal national park zoning as is, and consider developing ecotourism options that would not negatively impact the property. Therefore, it is recommended that the Committee request the State Party to halt the construction projects of the Galičica ski resort, as well as the sub-sections (a) and (e) of the A3 road. – says latest decision by UNESCO World Heritage Committee\nThe Ohrid SOS group has been on the frontlines fighting to save Lake Ohrid from the very beginning. It published the UNESCO decision urging the Macedonian government and European Bank for Reconstruction and Development (EBRD) to stop the further destruction of Lake Ohrid.\n.@UNESCO #recommends “to completely abandon the #Galičica ski centre project, keep the internal national park zoning as it is”. #UNESCOSays pic.twitter.com/YmrehT5SQJ\n— OhridSOS (@OhridSOS) June 9, 2017\nMeanwhile, the Center for Environmental Research and Information Eko-svest from Skopje worked on alternatives to the planned infrastructure project that will not destroy precious nature.", "739" ], [ "A feasibility study for a sustainable transport solution is scheduled to be presented in the Ohrid municipality this year.\nНие сакаме да го одбележиме #ДенотНаЕзерото со нашата визија за велосипедска патека која ќе кружи околу Охридското Езеро. Преубаво! pic.twitter.com/0eY7hvkCKO\n— Eko-svest (@Eko_svest) June 21, 2017\nWe want to mark #TheDayOfTheLake by sharing our vision for a bike trail that would encircle the Ohrid Lake. Beautiful!\nInstead of a new highway that would cut through the national park forests and block access to the water, the group is proposing a combination of transport alternatives that would not interfere with the ecosystem.\nPhoto shows Smart Ohrid transport solution with routes for cycling, solar boats and solar buses arround the lake. Photo by <PERSON>, used with permission.\nTo commemorate 21 June, Lake Ohrid day, the newly elected Macedonian government opened its doors to civil society and held an event in parliament where the president of the Assembly addressed the guests.\nI am especially glad that today in the Assembly of the Republic of Macedonia there is an event related to the initiative of the civil sector for the protection of the Ohrid region as the only region in the Republic of Macedonia protected by UNESCO. – said The President of the Assembly, Mr. <PERSON>\nThe parliament speaker stressed the readiness of the government to discuss and support citizen initiatives for the protection of the environment. An informal group of Members of Parliament from different parties was also formed named “Friends of UNESCO.”\n#Macedonia CSOs present parliament speaker, minister with citizen request to preserve #Ohrid lake and region. Parliament opens to citizens. pic.twitter.", "363" ], [ "Why Did the Giant Ears Cross the Road? To Protest State Surveillance in Macedonia · Global Voices\nThree activists from Metamorphosis Foundation cross the street to the Macedonian government building in Skopje, wearing eyeball and ears costumes to symbolize the illegal surveillance that civic society organizations and journalists have been subjected to. Photo by <PERSON>, used with permission.\nA human-sized eyeball sandwiched between two giant ears cross the street before a government building in Skopje, Macedonia. The trio performed a larger-than-life act of eavesdropping to protest mass state surveillance of journalists and civic groups, an activity that leaked recordings of illegal wiretaps have proven the Macedonian government has been engaged in for years.\nBehind the eye and ears (and the distinct reference to the Beatles’ Abbey Road album cover) were activists from the digital rights non-profit Metamorphosis Foundation and the informal coalition Citizen for Macedonia, who staged the demonstration to honor Freedom Not Fear, an EU-based campaign against mass state surveillance.\nThe big eye pretending to read a newspaper while spying on the municipality of Centar and the mayor, <PERSON>. Photo by <PERSON>, used with permission.\nA massive trove of audio files and archives (known locally as “bombshells”) released by opposition leader <PERSON> almost one year ago revealed that the communications of more than 20,000 individuals in Macedonia had been secretly recorded illegally, including more than a 100 journalists and civil society activists.\nThe big eye and ears took a stroll on 16 October from the government and the headquarters of the ruling VMRO-DPMNE party to the Helsinki Committee for Human Rights, the municipality of Centar, the European Union delegation's building, the weekly magazine Fokus and the Metamorphosis Foundation, where the Meta news agency and Portalb news portal are situated.\nThe big eye and ears in front of the EU delegation's building in Skopje. Photo by <PERSON>, used with permission.\n<PERSON> party claims to have obtained these records from whistleblowers within the Ministry of Interior and has since used them to expose the wrongdoing of the ruling party and, most likely, to draw more supporters into their own ranks. These corrupt behaviors were not news to anyone in Macedonia, but the hard evidence was welcomed by rights advocates who have worked for years to improve transparency and increase public accountability for spending and policymaking by the ruling government.\n<PERSON> (left) from the Directorate for Personal Data Protection and <PERSON>, founder of cybersecurity.mk took part in the debate on “Safety of communications and threats from monitoring and surveillance of communications” (Photo: Metamorphosis)\nAlong with the activists’ public demonstration, on 19 October Metamorphosis hosted a debate on the safety of communications and threats from monitoring and surveillance of communications.\n<PERSON> from Macedonia's Directorate for Personal Data Protection participated as a speaker in the debate.", "739" ], [ "She addressed the role of telecom operators in the process of eavesdropping, collecting and processing data from telephone conversations:\nThere are standards according to which communications can be monitored and personal data can be collected, and every violation [of these standards] is actually a violation of privacy. Telecom operators and [Internet service providers] should have mechanisms for guaranteeing their user’s privacy, and providing safety and confidentiality of their data and communications. They need to take technical measures to secure the data, and destroy the data if the purpose for their collection has been fulfilled.\nRecent reforms require telecommunications operators to build “back doors” into their technologies so that the Security and Counterintelligence Service, known as UBK, can listen to the conversations of just about anyone it chooses. Although the Constitution requires that the UBK obtain a court order before doing so, the new policy and practice disregards this requirement altogether.\nIt seems that the telecom operators have been compliant in this illegal surveillance scheme all along. According to <PERSON>, telecom operators in Macedonia collect and store all telephone metadata for 12 months. European Union regulations would prohibit such a lengthy storage period, an important detail as Macedonia is currently seeking accession to the EU.\n<PERSON> also confirmed that the directorate has not initiated proceedings on behalf of citizens affected by what the wiretaps revealed, and explained that this is because none of the individuals who were wiretapped had submitted a complaints about their cases thus far. This is not surprising, given rapidly declining levels of citizens’ trust in their government.\nBesides the debate, a workshop on the safe use of mobile phones was held in Skopje (Photo: Metamorphosis)\n<PERSON> from Internet Hotline Provider – Macedonia, a local civil society organization that works on the protection of digital rights, spoke on instances of online harassment in which wiretap recordings have been used to embarrass or shame political elites.", "409" ] ]

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[ [ "Unsure of what to do exactly\n(Please tell me if this belongs in another sub I wasn’t really sure where to post this)\nI rescued a baby sparrow today while at a friend’s house. It got a minor injury from a cat. I’m caring for it since I have experience raising baby birds. Once it’s made recovery and becomes an adult should I release it or have it remain as a pet? Since I’m hand feeding it now and such I’m worried it wouldn’t know how to search for food if I released it back into the wild.", "176" ], [ "Saved a really small kitten from an attack, it has an injury (help)\nI was on my way home from work this morning (4:30AM) and heard a loud cat mewing/agitated noise, I’m familiar with the cats in the area so I went to go check it out.\nI found a male cat batting around a small kitten (maybe around 3-4weeks old) and managed to chase it away, I picked up the kitten in my work apron and I have it with me but upon inspection, it has a broken back leg.\nThe vet does not open for another several hours, I don’t know if I can make a splint for something this small but upon doing research vets won’t fix something for a kitten this small\nDoes anyone know if this is true? I don’t want the kitten to keep limping and walking on it and don’t know what to do.\nThanks in advance.", "176" ], [ "Best beginner birds?\nHey! I’m not currently looking for a bird, but it’s on my list of pets I’d want. Ideally a bird that’s good with handling, and not a Budgie (something a bit bigger such as a Pigeon).", "894" ], [ "A pigeon would be great but I’m unsure how cuddly they can be even with lots of handling and training. I’ve had a Diamond dove but he hated everyone.\nAlso no farm birds (I already have a list of ducks and chooks), indoor birdies only. Willing to pay up to 300 for the bird itself, but obviously I’ll pay anything for the birds care.", "661" ], [ "I can’t get this kitten to pee or poop.\nI have this kitten that was abandoned. He’s no more then 2 weeks old, and in the 36 hours I’ve had him he hasn’t pooped or peed once. (If you want a little more context on this I made a post about it yesterday, you can find it in my profile.) But he hardly drank any KMR milk yesterday, he’s drank some more today, and has been ok for the most part, but I can’t get him to poop or pee. I’ve tried all the tricks people say, rub his lower belly with a warm towel to simulate the mother licking him but nothing comes out. Is it just that he’s not getting enough milk in him? Is he constipated? I have no idea how to take care of a kitten this young, I’ve been stressing all day, and no, the vet is closed, no vets on call, no nothing.", "833" ], [ "I live in a rural area and it’s thanksgiving weekend in my country. It’s currently about 9:00 Sunday night, and I won’t be able to get him to a vet by Tuesday morning. When I do try and make him go to the bathroom he feels panicked, and starts meowing like crazy. Is there any tricks I can use to get him to go to the bathroom. Cause the standard ones aren’t working.", "833" ], [ "Am I too late to vaccinate my cat?\n6 months ago, I found a kitten near trash dumpster. I gave him some food and he started to follow me back so I took him in. I am not a cat person and I was in no way financially fit to even vaccinate that kitten.", "176" ], [ "I just managed to skip my lunch few times a week to get his cat food and litter. Infact, I hid him from landlord because I couldn’t pay for him. I did post on facebook so someone could adopt him but I haven’t had any", "940" ], [ "Found a freezing kitten outside\nEarlier today at the store I work at someone found a freezing kitten in the parking lot. She brought the kitten in, and he was very cold and shivering, its been around +5 Celsius today, so it’s quite cold. I wrapped him up good and he warmed up, did a little bit of research online so I bought some corn syrup, eggs and canned evaporated milk from where I work. I left work for lunch with the kitten and mixed the evaporated milk, 1 egg yolk, and 2 tablespoons corn syrup, along with an equal amount of boiling water. He drank a little from a syringe but he doesn’t want anymore.", "940" ], [ "I’m not sure how recently he was properly fed though. He was moving around a bit more and had some energy, but he’s having a nap right now, and is good and warm. It’s currently Saturday, and I won’t be able to go to the vet until Tuesday and get him the proper milk, as it’s thanksgiving weekend and most places are closed. Until then what should I do? I have 4 cats at home, but they are all fully grown now and I've never had one this young, I would say he’s only 1-2 weeks old. I’ll keep warming up the milk I made him, but what else do you recommend I do to help this kitten? I also should mention, the lady that brought him into the store thinks someone just abandoned the kitten there. Cause there’s no way that kitten could have wound up in the parking lot all by himself.", "176" ], [ "Found stray kitten at work\nAs the title says, I found a stray kitten at my job Saterday, May 13th, and took it home. However, I already have 2 pets, and this kitten has a rather sick eye. I already gave her a bath both in dawn for flee removal and any other mites that I may not have been able to see and washed her in baby shampoo. I have cleaned out her ears, and I am trying to keep her eye clean as much as possible. It seems the tear duct is swollen and produces a lot of water. She is also fed with water and roughly around 3 to 6 weeks old. My dog is curious while my cat, who is 10 months old, wants absolutely nothing to do with the kitten.", "664" ], [ "Because of the odd relationship cycle between the animals and financial standings, we do not plan on keeping the baby and am only fostering until her eye gets better. She also has not shown signs of using the bathroom. Any advice?\nUpdate: she has started using the bathroom, but the eye is still sick, still trying to keep it clean as much as possible. I have called multiple local pet clinics, and only 1 was able to give me a full estimate of the price of antibiotics and possible treatment. The highest would be anywhere to 95$ to over 100$. My husband and I have decided to name her tŭdy. Would really like any advice.", "881" ], [ "Moving out\nI’m moving out of my parents home for the first time in the upcoming weeks. The problem is my little kitty <PERSON>. I went and got <PERSON> a little after COVID for the family with my mom at an animal shelter. Ever since we first met her she had such a loving and different personality that we had to take her home that day. She’s almost 2 now and is truly a one of a kind kitty. She’s never hissed at us unless in a really stressful situation nor does she do things maliciously.", "679" ], [ "She is very vocal and likes to do things like fetch and stuff. I like to think of her as half dog half cat. Anyways whenever I think about having to leave and not bring her with me I get very upset. My mom and older brother are also very attached to the cat and I don’t want to take her away from a place where she has more company and people. She is also very close to my mother so I know she would get the company she needs. I guess I’m asking for peoples personal experiences or if I should get another kitty etc etc. Thank you :))", "679" ] ]

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[ [ "This is my first review on BGG. Which isn't my way of asking you to be kind. Take it more as my way of an introduction.\nI played the demo at Gencon and bought the game - actually the truth is I bought the game at Gencon then played the Demo. I then played the full game about 6 more times with about an equal mix of 2 and 4 player games.\nFor simplicity if I say TM it's the Blood Bowl Team Manger game BB is traditional Blood Bowl. I'll note now - I'm a huge BB Fan (and now a huge TM fan).\nThe basics are already covered pretty well in other threads or by just going to the info on FFG's site. I personally haven't played all the teams yet myself, but I've either played or played against them in various combinations.\nYou pick a race and their corresponding 12 starting cards. These cover the typical BB starting player teams. For example the starting players for Orc's have several line men, some black orcs, some blizters, some throwers and a troll (I don't have the game at hand for an exact count).\nThe races in TM are built around similar concepts to how they are built in BB. (just 3 examples)\nOrcs play slower, speed in this case relates to how fast you can cycle through your deck, But they are tough, block a lot, cheat a bit regularly and can handle the ball.\nWood Elves by contrast are quick (lots of deck cycling) really good at getting the ball but aren't as good at blocking and don't have as many strong players and don't cheat.\nSkaven are kind of like Wood Elves in that they are really fast, good at getting the ball, not so tough but they cheat a lot.\nThe other teams all have similar balances to their BB heritage. Personally I've played Orcs x3 , Skaven x2 and Chaos. I found that each team felt very different and each required their own strategy. I also had to adapt different strategies depending on who I was playing. Much like you would in BB.\nYou play cards from your hand to try and have the most star power on a given highlight. Whoever has the most wins the highlight reward and whoever still has players involved gets the side line bonus. If you manage to win a highlight and no other team is involved, perhaps because no one did or you injured all their players you get all the rewards (rare in 4 player games more common in 2).\nIt's kind of a hybrid bidding/area control kind of balance. You are committing your players, which really are your only resource, to capture the highlights - which are the area's of play.", "366" ], [ "But unlike most bidding games you can actually attack other players. I really like the strategy here and there is a very interesting shift between being able to play first in a given round or last. Playing first gives you the first pick of choice, but last card can be as powerful if not more in the right circumstances.\nIn terms of complexity there are more rules to it then Dominion for example, but it's by no mean a steep learning curve and the rule book reads well. However I have to caveat that by saying I had the luxury of playing the demo first. But after the fact when we ran into some situations not covered in the demo (like setting up the game or playing with 2 players) it was easy enough to find the answers in the book.\nThere is a good amount of strategic decisions going on in this game. Such as which highlights to go after, which players to use and which bonus cards to get when you have a choice. But also like in a good card game you also need to really keep track of what your opponents are doing.\nIt's not enough to just play your cards. A good player needs to try and think of what cards other people have played and may have left to play. Not only during the current round, but also what they have played in the past rounds. All these choices could create some AP for some players. But it hasn't been my experience yet. Also each turn within a season your options reduce as you start with 6 cards, then down to 5 - 4...1 so by the last turn you really are just picking where you want to play. It also has a similar flow to BB where you first are looking at what to do with your whole team and need to decide do I go for a safe action or a needed action. Then as you move each player your number of choices reduces.\nIn terms of strategy you will probably have an overall goal for the round. Typically based on which highlights and/or tournaments you want to win or just take part of. However just planning that isn't enough because you will need to shift your plan around based on the actions of others. I never found my turns to feel empty and I was definitely paying attention to what all the other players were doing, again much like BB.", "884" ], [ "Been playing a lot of Swords and Sorcery since it came in. There are some things I really like, and some things I wish were different. My list to follow, but what are your Pros and Cons for the game? If you would rather listen to my thoughts (along with my design partner <PERSON>) here is a link to our podcast: https://soundcloud.com/user-318456537/co-op-cast-episode-4-s...\nPros:\nMap Setup - Don't get me wrong this is no walk in the park. But compared to other games of it's ilk (Descent, Gloomhaven, Imperial Assault, etc) it is pretty easy. There are only 20 double sided tokens and they are all numbered (I am looking at you Gloomhaven and Mansions of Madness). Also when you build the maps they show the printed number in the correct corner of the map. This seems line such a simple thing, but I don't remember it in other games. Or maybe to keep the emersion they make the numbers small in other games. Either way it is easy to see how to orient the tile. You don't have to guess based on clues in the art. Also, there aren't 100 overlays, the amount of stuff you add isn't that bad for the amount of variety the game provides.\nVariety - The heroes feel different. The weapons feel different. The enemies feel different. Even if you get the same enemy they may have a power which will make them play/ feel different. Maybe two dexterity characters will eventually end up feeling similar if you level up the same, but that is your choice.\nFeeling of Progress - Everything you kill is giving you soul gems and gold. Gold can buy you all kinds if things including temporary boosts like upgrading your items for one mission or getting consumable potions. In most games I don't buy these things, but this game throws enough money at you that it feels cool to get those temporary boosts and I can still buy all I want/ need. Leveling up is fun and I always look forward to it, and because you share soul gems it feels line the team is always leveling even if it isn't you personally. And I want to see what cool things my buddies can do too.\nCool/ Powerful Items - Right from the very start we were upgrading our weapons. But even your early weapons are pretty cool/ effective. Maybe you need to temporary boost them for the next mission to make them better until you find a better weapon so you can spend your coin on something else, but all weapons and equipment seems good, just different. Even the legendary items aren't that much better than stuff you find in the wild.", "366" ], [ "But they are all different in the skills they possess. So if your skills knock them down, you don't need the weapon that also knocks them down. Cool choices without someone becoming way more powerful than their teammates (looking at you Zombicide and Gloomhaven).\nDifficulty Scaling - The difficulty and complexity ramp up and you play along. Nothing really telly you that, but they introduce it slowly and steadily. You only learn a few new enemies at a time so that is good too. And there aren't that many enemies in the board that it is hard to keep track of what is going on. Although you will miss things as noted below.\nCons:\nFiddly - With all the variety there comes a cost. Every enemy has lots of special powers and text. Lots if modifiers to your attacks. You will miss something. You will probably miss a lot of powers/ modifiers throughout the game. In 2 player there aren't a lot of enemies on the board, so it isn't that big a deal, bit I can imagine it would be very hard to keep track if everything in higher player count game.\nSetup - While they made the map setup very clean compared to other similar games setup still takes a while. The cost of variety here is that you have to pull out different enemies for to add to the enemy deck. Then get their big cards to reference them. You also need to set up the story deck and find the correct enemy tokens and other tokens to add to the board. It isn't as overwhelming as other, similar games, but it still is long and tedious.\nSkill Power Levels - This is a problem with almost every one of these games, and is true here too. Maybe even more so in some cases. When you level up there is almost always a \"best choice\". If you build a character, there isn't a whole lot pushing you to build them differently the next time you play. There are 5 characters, so you have choices to play something different, but you will probably build them similarly to everyone else building that character.\nBoth:\nStory - the story is good and is keeping me wanting more. There are a lot of references in there though which breaks immersion a bit. Feels like I am watching a cheesy B movie.", "884" ], [ "Please check out my Geeklist at:\nhttps://boardgamegeek.com/geeklist/145695/purge-reviews-reco...\nMy video reviews can be found here:\nwww.youtube.com/purgereviewsboardgames\nConclusion:\nLong Shot was my favorite horse racing game and one of my go to party games. It accommodates a lot of players and everyone understands the concept of horse racing. It was and is an easy sell so when the Dice Version was released promising to be smaller, quicker, and just as good I have to admit I was intrigued.\nLong Shot the Dice Game improves on the original in almost every way. I will list a few pros and cons to this game:\n1. The game is short. It usually takes about 30 minutes to play the game. It doesn't over stay its welcome and plays in about the perfect amount of time. The original was more like 60-90 minutes so this is an improvement but you will need another game to play on the same night where the original was a game to center the night around.\n2. While I really like the look of the game, the original is larger and fills up a table better. A lot of people are going to like the compact nature of this game, but it is a tad small for 8 people. I may be in the minority, but I would like a Jumbo version of this game. Larger cards, bigger horses, etc.\n3. The game is easy to teach. You roll some dice and everything works off the dice. People understand instantly the roll and move mechanic and betting on the horses. It takes just a couple of minutes to teach the game and most people will be able to play without any questions.\n4. The game is full of luck. That's the game. It is all about profiting off that luck and pressing your luck to generate more and more cash. The horses are going to move on their own, but you can start to add marks to the horse to influence the horses you want to move. I guess that is the best way to comment on it: you are trying to influence the horses and the outcome. Some people are going to like this and others hate it.\nOverall, I have to admit I love this game.", "581" ], [ "I've been playing the solo game over and over trying to beat that <PERSON> character. I've played this with a lot of different player counts and it does a good job of keeping you invested when it isn't your turn. The game mitigates this by letting you take an action on other players turns. That's a great fix.\nI can highly recommend this game for people who want a horse racing game and like to have fun. This is a dice rolling, horse betting, take out your opponents good time and one I'm willing to play anytime.\nKeeper.\nComponents:\nThe components are top notch for a roll and write and a light filler. The horses are silk screened on both sides and fit the smaller board perfectly. The dice are a tad on the cheaper side, but they do get the job done. You get plenty of dry erase markers which are pretty standard for this sort of game. Everything has a great look to it and I like the choice of sillier art work. The package is very, very good for the price point.\nRule Book:\nThe rule book takes about 15 minutes to read. The rules are full of color and has plenty of pictures and examples. This is a very easy to read rule book and everything seems to flow perfectly as you read through the rules. The book is easy to digest and to use as a reference while playing.\nFlow of the Game:\nThis is a horse racing game. The race is over when 3 horses finish the race. Each horses is awarded a place (1st, 2nd, 3rd).\nPlayer Turn:\n1. Roll both dice\n2. One die is the horse to move; the other die is how many spaces to move (1-3 spaces); then move all the horses listed on the card 1 space only\n3. Then, each player takes an action in turn order based on the die identifying the horse:\na. Bet on the horse rolled\nb. There is a chart where if you finish a line you get money, free bets, move the horses, etc\nc. Add a helmet - this allows you to bet after the horse crosses the no more bets line\nd. Add a jersey - this allows you to mark for another horse to move when this horse is activated\ne. Purchase a horse (each horse as a power that is activated when the number is rolled)\nYou score points if a horse you own places, each helmet/jersey combo is worth 5 points, gain money for bets plus any money left over.\nMost points/money is the winner of the game.\nShould I buy this game?", "629" ], [ "This review continues my series of detailed reviews that attempt to be part review, part resource for anyone not totally familiar with the game. For this reason I expect readers to skip to the sections that are of most interest.\nImage Courtesy of <PERSON>\nSummary\nGame Type – Dice Game\nPlay Time: 20-40 Minutes\nNumber of Players: 2-5\nMechanics – Dice Rolling, Dice Management\nDifficulty – Pick-Up and Play (Can be learned in about 10 minutes)\nComponents – Good\nRelease - 2012\nDesigner – <PERSON> (All things Bohnanza, Agricola, At the Gates of Loyang, Babel, Le Havre, Ora et Labora)\nOverview\nWhen I started my journey into the new age of gaming around 2000-2001, Bohnanza was one of the first games I played and I loved it.\nThat still rings true today despite the fact that I play it far less than I used to. So when I heard that the <PERSON> family finally had its inevitable dice game conversion, I knew I had to try it. I prepared myself however for the worst and despite my love of dice games in general, I am getting pretty tired of the current trend to turn almost any successful game or franchise into a cheap and easy dice spin-off version.\nDespite being a dice game, the theme found here holds largely true to the original card game. Players are trying to roll dice in order to plant beans (lock them in), which can then be harvested once a harvest order is completed in full. The more harvest orders that are completed, the greater the payoff when a player decides to cash-in.\nSo how do the old beans fair when they are on dice? Is this a cynical money making exercise or a gaming experience worth your hard earned? Let's find out.\nThe Components\nLike any good filler dice game the components required are fairly minimal...\nDice – The stars of the show are the 7 dice that feature a total of 7 different bean types. Most are common to the card game.\nWhat requires mention is that the dice are split into 2 distinct dice types or sets, a group of 4 like dice and a group of 3 like dice. Both sets differ in the types of beans they offer and how many of each.\nStraight away it becomes evident that the game may require some dice management to maximise your results and this is certainly true.\nThe group of 4 like dice feature a white background, whilst the set of 3 like dice feature a beige background. At best this colouring is not highly evident and at worst it is very hard to see under poor lighting, which is a shame but not a game breaker.\nMost of the time it is not an issue but something could have been done to rectify it in production.\nThe faces themselves are painted on rather than etched but mine are yet to show any serious wear.\nPlease note that in the image below the orange looking dice has been coloured by the owner to help better identify the beige from the white dice. I have not felt the need to do this.\nImage Courtesy of Liumas\nHarvest Cards – The other major component is the Harvest Cards, which the players are trying to fulfill with their rolls.", "581" ], [ "Each card features a total of 6 different orders and the criteria for each order is listed using icons that are easy to understand.\nThe other feature worth noting is that coins/gold or (in Bohnanza speak) Beantalers are listed on the top half of the card. These BEantalers (1-4) are the rewards on offer for completing 3 or more orders.\nThe backs of the cards feature the same classic image of the golden Beantaler, that every Bohnanza game tends to use. These are used to keep track of a player's score as they complete orders and collect their gold.\nThe cards are a nice bit of design. It isn't necessarily impressive but it does the job, is easily understand and allows the game to flow quickly and easily. The cards also feature a matte or linen finish, which is in keeping with the European quality standards that companies like Amigo tend to uphold. Bravo!\nOne element I do like about the Harvest Cards though is that there is much variety in the orders that you need to complete. In all there are a total of 64 cards and 9 different types of orders (with many variations within those types) that need completing. This variety helps the game to feel varied.\nImage Courtesy of Artax\nBean Field Template - A box-sized Bean Field Template is also provided. This is an important feature as it serves as a location for the players to move their 'locked-in' beans to and helps avoid having rolled dice hitting 'locked-in' dice. It also helps to easily identify which dice are still active and which are not.", "872" ], [ "Image Courtesy of <PERSON>\nThis review continues my series of detailed reviews that attempt to be part review, part resource for anyone not totally familiar with the game. For this reason I expect readers to skip to the sections that are of most interest.\nIf you liked the review please thumb the top of the article so others have a better chance of seeing it and I know you stopped by. If you thumb the bottom as well, I consider that a bonus. Thanks for reading.\nSummary\nGame Type – Roll and Write (Dice) Game\nPlay Time: 30-50 minutes\nNumber of Players: 1-4\nMechanics – Dice Rolling, Paper and Pencil\nDifficulty – Pick-Up & Play (Can be learned in under 10 minutes)\nComponents – Very Good\nRelease – 2018\nDesigner – <PERSON> -( Brikks, Fuji, The Mind, The Quacks of Quedlinburg)\nOverview and Theme\n2018 was a big year for Roll and Write game designs with this title nominated for the Kennerspiel des Jahres, Welcome To...was also released and two Kickstarted titles in Roll to the Topand On Tourlaunched. And I have left off a few more that spring to mind immediately.\nFor those not aware of the genre, Roll ‘n’ WriteGames have been around for decades because Yahtzeewas perhaps the first of its kind. It simply means that you must roll some dice and record one or more results on a scoring sheet of some kind. Now don't be turned off by the Yahtzee reference because this is the 21st century and the genre is getting a little more gamer-fied. I should also probably mention that the genre is being pushed in some diverse directions and the popular Welcome To... is actually a draw and write (as in you draw cards as opposed to rolling dice).\nSo is Ganz schon clever as good as all the cool kids are making it out to be? Where does it sit among the numerous titles that this genre has spawned over the last 3-5 years?\nLet's go into the sitting room to find out. Oh grab that silver platter will you...we will be needing that.\nThe Components\nTwo elements that define a Roll ‘n’ Write game are the fact that they tend to be fairly small in terms of their footprint and the game play is usually directed by the options on the scoresheet itself.", "470" ], [ "This is certainly the case for Ganz shon clever.\nScore Sheets – The scoresheet that each player receives consists of 5 scoring areas in the colours yellow, blue, green, orange and purple. I will outline the function of these in the body of the review.\nAbove those 5 scoring areas is a round track, 2 horizontal rows to record some additional bonuses that can be earned and 3 vertical white spaces, which serve as locations to assign taken dice.\nBefore learning the game it might look a little confusing with all the various icons, arrows and values all over the place. But once you learn the game it all makes total sense and is highly functional.\nImage Courtesy of <PERSON>\nDice – The game comes with 6 wooden dice that are standard six-sided affairs (values 1-6). Five of these dice come in the colours of the 5 scoring areas - I'll let you make your own assumptions as to the connection for now. The last dice comes in white.\nThese are about as standard as they come. I don't know how random the assortment of dice is in the various editions around the world but I have a copy (German Language Edition) that features pips in black and another with pips in gold. I can't see any logical purpose for this as the dice colours with gold pips do not have any special connection to one another (they are the purple, green and blue dice in my copy). I would imagine they were just randomly grabbed at production.\nImage Courtesy of <PERSON> & Rules – The game comes with 4 small black markers that can also work on dry erase boards in other games.\nOf course they only last so long before you need to get some better quality ones.\nThe rules are where the production errs a little. The English translation (from the original German release) is a bit confusing in places but I've even seen some German gamers comment on the forum pages that the English translations weren't where the problems started...that some of the rules written in German are a little ambiguous also.\nThankfully we are Geeks and can find the solutions we need. Hopefully the English edition\\later printings can spell things out more clearly.\nImage Courtesy of Alice87\nPackaging – I really like the small packaging that most Roll ‘n’ Writes allow. But I'm really mentioning this point because inside the box is artwork that represents a Silver Platter.", "872" ], [ "My friend's store did the order x amount and get a demo version (think x was 8). Came in yesterday in time for game night (normally EDH, multiplayer Magic) and we were hungry to dive in. This whole review is based off a 5 player deathmatch that we played.\nIt's his store's copy so I do not have it in front of me to help with the review. This is being done from memory so I apologize if I mess up anything.\nInitial impressions:\nWe opened the box and oh my gosh look at all the chrome.\n5 pre-painted Planeswalker figures that were reasonably well done.\n6 Creatures of two types for each planeswalker/color in colored plastic of the planeswalker/color (eg: 3 Kor Hook masters and 3 Rhox for Gideon/White).\nFor each creature type there was a matching card with stats and abilities. Also a card for the planeswalkers with their stats and abilities.\nThere were 10 white heroscape dice (swords/shields/blanks) and black D-20 for first player and various abilities.\nA Deck of Spells (I think 60 total, 12 in each color).\nThe printed terrain boards with planeswalker story/fluff on the backside of each one. 4 Runes to activate on the board for bonuses (I think 4, we only played with 4 of them). 2 large cardboard stand up that interlocked to stand on the battle field and provide cover. Several Heroscape tiles to form a mini hill.\nRead through of the rules:\nIt's Heroscape...OK there are some extra's but it's Heroscape. This was one of my biggest gripes...the rulebook. It did a very good job of covering all of the existing Heroscape aspects, moving up levels of terrain, line of sight for attacking with creatures, falling damage, etc. What it didn't cover well was the added things. Casting spells, summoning creatures, spell targeting. It had the basics of those things but when we got into the game we were constantly trying to look up answers to questions and coming away frustrated (Hasbro,START BUILDING A FAQ).\nBasic turn structure:\n1) Draw a spell card (S)\n2) Declare an active Squad/Planeswalker card for the turn (S)\n3) Move active Squad/Planeswalker figure(s)\n4) Attack with active Squad/Planeswalker\n5) sorry can't remember the name of this step but it allowed (S)\nSo you have your Planeswalker on the board. For the first turn that's the only card you can declare as active and move with. Now the rules stated that between steps 2 and 3 your Planeswalker can summon \"up to two squads\" worth of creatures.", "386" ], [ "Once those creatures are summoned their cards are considered active and you can activate them for turns as long as the figures are on the board.\nThe summon paragraph is thrown in there like it's an afterthought though. A big part of the game is to summon creatures to fight for you and you can do it on an unofficial step wedged in to an existing system.\nThe other big part of the game here is the spell cards. There are only two types currently, Sorceries and Enchants. Spells can only be played on your turn and only in certain steps (1,2,5 where I put a (S)) at least that was our understanding from the rules. While this got more than a paragraph it did not get a full page. Whenever unanswered questions came up we applied MTG logic to the spell and it seemed to work.\nThere is no spell cost and you can cast up to three a turn.\nPlaying the game:\nIt was 5 player Heroscape. Once we got our squads summoned on the board it was exactly like previous Heroscape games except for the ability to only activate one character/squad and to be able to choose each time my turn came around. The spells were a nice touch and added a nice twist on the game. Each color had cards that looked or were named after MTG cards and did much the same thing as the named card. Blue even had counter-spells.\nBiggest Gripe here was the turn counter. They give you an impossibly small counter and you have to use the rule book to track turns (with the small counter on the page in the appropriate circle).\nFinal Thoughts\nIt may sound like I was not happy with the game but that's not true.\nI was mostly frustrated with the rule book. Hasbro has made an effort here to make Fantasy Flight look like the <PERSON> of rulebook writing. I honestly gave up looking about an hour in. It covers almost any Heroscape-esqe query excellently. All of the additional material feels severely bolted on.", "386" ], [ "Image Courtesy of vittorioso\nThis review continues my series of detailed reviews that attempt to be part review, part resource for anyone not totally familiar with the game. For this reason I expect readers to skip to the sections that are of most interest.\nIf you liked the review please thumb the top of the article so others have a better chance of seeing it and I know you stopped by. Thanks for reading.\nSummary\nGame Type - Euro Game\nPlay Time: 75-100 minutes\nNumber of Players: 2-4\nMechanics - Set Collection, Worker Placement, Meeple Management\nDifficulty - Moderate (Takes a few plays to get a good grip on the moving parts)\nComponents - Excellent\nRelease - 2011\nDesigner(s) - <PERSON> <PERSON>( A Castle for All Seasons, Guatemala Cafe, La Boca, Saint Malo)\nOverview and Theme\nWelcome to generic-ville. It could be a village anywhere in the middle ages, Medieval times or the times of <PERSON>. It has a church, council chambers, farmland, a marketplace and a whole raft of skilled craftsman. It’s a place where dudes wear feathers in their hats, writing is done with ink and quill and getting from here to there is done with horse and cart. The ladies wear dresses covering them from neck to toe and life passes from one season to the next.\nThis is Village, a worker placement Euro with a twist that has helped it stand out from the pack and had many a Euro-phile excited over the past few years.\nAdding to the buzz, Village picked up the Deutscher Spiele Preis - Best Family/Adult Game in 2012 as well as the Spiel des Jahres - Kennerspiel des Jahres (Special mention) in the same year. This award would suggest that Village was considered just a little too heavy for the SdJ. Games Magazine then honoured it with their Best New Advanced Strategy Game award in 2013.\nSo get your ‘townsfolk’ on and take a walk down the quaint cobbled road with me as we take a look at what all the fuss is about.\nThe Components\nVillage isn't trying to beat around the bush...it's a Euro and it wants you to know it. The good news here is that the game offers up top notch production values and the artwork helps the theme to shine through the mechanics.\nBoard – Village offers up a nice square board that depicts, not surprisingly, a village. It is made up of various buildings and notable features. In the distance a series of towns and cities can be seen to entice the intrepid traveller.", "470" ], [ "Like any good Euro there are icons plastered all over the place but they are not overwhelming at all.\nSurrounding the board is a score track, which tracks each player's VPs, which the game refers to as Prestige. Rather than using just simple numbers the track uses the image of a scroll page, which is a nice thematic addition.\nOverall the artwork is really well done without quite being up to the standard of a . But hats off to <PERSON> all the same. I suspect we will be seeing more of his work in the future.\nImage Courtesy of <PERSON>\nFarm/Player Boards – Each player is given a mid-sized Farmyard Board to depict the family holdings. Each is a different colour and a farm complete with a barn and a house is featured. Around the border a time-track is present, which makes use of the iconic hourglass motif.\nThe boards offer a lovely thickness that screams 'I'm a quality production!'\nImage Courtesy of EndersGame\nVillager Meeple - No worker placement game is complete without meeple and Village offers each player no less than 11. Before any game can be played each set of meeple must be stickered on the front and back so that each one features a number.\nEach player will have four meeple with a 1, three with a 2, two with a 3 and two with a 4. These numbers represent the generation that each meeple comes from within a given family, which I will elaborate on later.\nThe game also comes with 4 black meeple, which represent Monks. These are owned by no player but they also require a sticker, although there sticker features no number. The reason for which will become apparent as I outline the game.\nImage Courtesy of EndersGame\nPlayer Markers - The other wooden component in the game comes in the form of wooden discs. These are used to keep track of a player's score, their time track and also to record where they travel to in the course of the game.\nImage Courtesy of EndersGame\nGoods Tiles – In the game the players can create 5 different types of goods. These take the form of smaller oblong shaped tiles.", "84" ], [ "Like many others I recently had a chance to attend a preview session of Mansion of Madness. I thought people might like a comparison to Arkham Horror. So instead of your typical review that many have already posted I will breakdown these two <PERSON> theme games and point out the differences and similarities. So here we go...\nComponents:\nAnyone familiar with Fantasy Flight already knows if there is one thing they do well it’s definitely the \"What’s in the box!\" factor. That being said they really stepped it up in Mansion. In Arkham the player pieces were flat images on a stand which gave the game a classic retro feel. Also the monsters were all represented by cardboard tiles. In Mansion the player pieces are fully modeled plastic pieces. However it’s the monsters in Mansion that really steal the show. Some of the figures are quite large and detailed. One of the folks I had a chance to play with during the demo mentioned that he planned on painting his figures when he got his copy. There are still tiles that list information for the monsters in Mansions but they are inserted into the base of the creature’s figure which I thought was a nice touch.\nSetup:\nIf I were keeping score Arkham would definitely win this category. The setup is huge in Mansion taking close to 30 minutes and that was with someone that had already played the game the previous night. I suspect a little better organization and some familiarity will cut this down but some things will just be unavoidable such as the keeper’s detailed setup. Having the investigators setup the board and pick out their own characters and such will definitely speed things along. Arkham’s setup was basically pick out the main baddie, pick your investigators (and give them their items), plop a gate down and dump the monsters in the monster cup. Due to the story element in Mansion there is a more tedious setup by the keeper in order to preserve the story element of the game.\nPlaying Time:\nOver the years I found the playing time of Arkham Horror to vary greatly. Mostly this was dependent on the familiarity of the game with the players. Obviously the more familiar folks were the faster the game went but it wasn’t the simplest game for newcomers so it was common to deal with a slower player. Another factor that makes it hard to pinpoint a game length for Arkham was the unpredictability of the board.", "386" ], [ "I have personally played games that have lasted 30 min (lucky draws) to some that have taken upwards to 3 hours (not so lucky draws). As for Mansion of Madness once the setup is done it’s some smooth sailing after that. The keeper turns will undoubtedly take the longest but if you have a good one (like any good DM) then things will run along at a nice pace. Any newcomers will likely take the role of an investigator which is quite simple to play. In my first game were able to get through a whole game in about 90 min which I thought was perfect.\nGameplay:\nArkham is a pure co-operative game while Mansion is co-operative amongst the investigators but obviously the player playing the part of the keeper is certainly not co-operating with the investigators. I believe the use of a Keeper (DM like) player really makes the gameplay in Mansion more satisfying. As innovative as the mechanics in Arkham are the game can’t adjust to your strategy and anticipate moves like a human player can.\nAnother issue I was never fond of in Arkham was the use of dice and I mean lots of dice to the point where you had to reuse some dice because you needed to roll so many. This is a thing of the past in Mansion as there is only one die in the box. Yep, you read correctly only one single lonely lovely die. It’s a 10 sided die to be more concise and it is used to make various stat checks during the game. If your roll is equal to or less of your required skill (i.e. Willpower, Dexterity), than you made a successful roll. It’s that simple.\nInvestigator turns are actually quite similar between both games. In Arkham you were able to move up to your speed and then perform one of several possible actions. In Mansion you get to move to an adjacent location up to two times and perform one of several possible actions. However these actions can be broken up meaning you can move, perform an action and then make your last move OR action first then move twice and so on... What is nice in Mansion though is that there is much less to keep track of than in Arkham which keeps the turns nice and simple. Arkham horror required you to always keep a track of several things that to be honest with you often got overlooked in some of our games. Things like how many gates are open right now (end game varies by players), how many monsters are in the streets (again monster surge varies with number of players) and don’t forget the monsters in the outskirts. What’s the current horror level at?", "884" ] ]

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[ [ "It seems that there are eukaryotes that can live above 45 C. There is a nice review article life in extreme environments that has charts out the upper temperature limits for each taxa, at least as known in 2001. This paper claims ~60 $^o$C and a different paper without a reference for it claimed the world record was 62$^o$C. So it seems that even with real organisms there may be a little more wiggle room for higher temperatures for your story purposes.\nreducing chemolithoautotroph, capable of growing at the highest temperatures of up to 113 $^o$C (ref. 15). Hyperthermophile enzymes can have an even higher temperature optimum; for example, activity up to 142 $^o$C for amylopullulanase 16. There are thermophiles among the phototrophic bacteria (cyanobacteria, purple and green bacteria), eubacteria (Bacillus, Clostridium, Thiobacillus, Desulfotomaculum, Thermus, lactic acid bacteria, actinomycetes, spirochetes and numerous other genera) and the archaea (Pyrococcus, Thermococcus, Thermoplasma, Sulfolobus and the methanogens). In contrast, the upper limit for eukaryotes is ~60 $^o$C, a temperature suitable for some protozoa, algae and fungi. The maximum temperature for mosses is lower by another 10 $^o$C, for vascular plants it is about 48 $^o$C, and for fish it is 40 $^o$C, possibly owing to the low solubility of oxygen at high temperatures (Fig.", "3" ], [ "3).\nI think the bottom up approach to adaptations, is interesting. But it seems like there are adaptations before a sharp temperature cut off. For example, DNA denatures in the lab ~ 95 $^o$C when doing PCR. I would have assumed that would be a hard cutoff, but apparently DNA in a hyperthemophile grows optimally at 100$^o$C. So the conditions inside the cell are more important than the stability of the molecule in isolation.\nIt seems that after cell membranes that the flexibility and stability of proteins is probably really important. I think the protein structures would need to be stiffer and less floppy at higher temperatures.\nIf I read you original goal correctly, the goal was to have a large animal and you wanted to avoid overheating in the center of the animal. Making the cells survivable to temperature I think is one thing, but another think to think about is how oxygen gets transported to the cell. I think with increased temperature that oxygen binding to hemoglobin decreases. Also in general the percentage disolved gasses in a fluid decreases with increased temperature.", "279" ], [ "We breath oxygen primarily because it's highly electronegative and hence works as an electron attractor in the electron transport chain system of atp production. This is a rather specific metabolic system and it's far from foundational, tons and tons of bacteria don't have this type of energy system, (in fact even humans have several others in addition to this one!)\nIn fact, there are really existing earth bacteria that use metals in their metabolic systems, and frequently absorb environmental sulfur or oxygen (or probably other things, maybe not hydrogen though, H2 is very stable) as a way of breaking down metals into more usable forms.\nReally you've just got to decide how detailed you want to get with this. Fully describing the chemistry of a totally novel metabolic cycle seems like it would be pretty hard, certainly it's above my pay grade. At the same time, I wouldn't doubt for a second the plausibility of \"a Bacteria which metabolizes [some metal] by absorbing [some gas] in a low oxygen atmosphere\". Hell, there's probably one on Earth that fits the bill.\nTo fill out this response with some more specific information, you can look at a couple of the following things:\n1: Sulfate Reducing Microorganisms: https://en.wikipedia.org/wiki/Sulfate-reducing_microorganisms -- these are examples of bacteria that \"breath\" sulfates instead of oxygen to power their respiration. In other words, they use sulfates as the final electron acceptor in their electron transport chain.", "938" ], [ "These are prokaryotes however. Some of these are called Chemolithoheterotrophs, which is the class of bacteria here that reduces inorganic material rather than organic material, which is kind of the thing you are looking for. 2. https://microbewiki.kenyon.edu/index.php/Dissimilatory_metal_reduction Here is a short article talking about how microbes can \"consume\" metals to produce energy. In your post you said you wanted the microbe to consume metals to gain mass, but keep in mind that for the most part the mass of a single microbe is naturally limited by scaling factor difference between volume (~mass) and surface area (~max \"eating\" rate), so for a colony of bacteria to gain mass by consuming metals you just need a metal to be \"consumed\" (usually this means corroded or oxidized) as part of the colony's metabolic process.\nI'd hoped to find an example of a specific Earth bacteria fitting your criterion, but I wasn't able. However, nothing about what you're asking for is too 'out of this world' (yuk-yuk) certainly the individual elements you're asking for are well represented and pretty well understood.", "561" ], [ "1) The authors propose that this is a distinct species based on a number of physiological and genetic tests. To quote the summary of your linked paper\nIn summary, the phylogenetic and genetic distinctiveness and differential phenotypic properties were sufficient to categorize these three ISS strains as members of a species distinct from other recognized Methylobacterium species. Therefore, on the basis of the data presented, strains IF7SW-B2T, IIF1SW-B5, and IIF4SW-B5 represent a novel species of the genus Methylobacterium, for which the name Methylobacterium ajmalii sp. nov. is proposed.\nThis indicates (emphasis mine) that they think that these isolates are distinct enough from species that we have found on Earth to make the isolates a species. This is a species that we haven't found on Earth, but unsurprisingly it is closely related to species from the same genus that have been found on Earth and on the ISS\n2) The authors make no statements about how the species came to be there that I could see, only that it is a novel species from the ISS, which has not been found on Earth.", "3" ], [ "No mechanisms for arisal are postulated, and the authors wisely did not speculate on this at all (speculation on results is frowned upon in science). One of the reasons they did not speculate on this will be that testing mechanisms whereby speciation has occurred is very difficult, especially as they would need to mimic in the lab the conditions in the ISS and show which conditions were important for the speciation. These experiments would be technically challenging and very time consuming.\nIt is worth noting that we don't really know the rate of species differentiation on Earth, let alone in space, partly because Earth is so covered in bacteria that proving that one evolved in the environment is difficult as it is hard to prove that you didn't just miss it last time you looked. To quote the paper I linked above:\nFor example, a single gram of soil can harbour up to 1010 bacterial cells and an estimated species diversity of between 4·103 to 5·104 species .\nHowever, the ISS is one environment where it might be easier to see these sorts of events because it is relatively micro-organism free, and we have prior samples to go back and compare to. For some comparison of the numbers, I turn to the second paper you linked, which found:\nOf the total bacterial and fungal isolates that grew, 133 bacterial isolates and 81 fungal isolates were identified by <PERSON> sequencing... ...When the ASVs were summarized to the genus level, 121 taxa were detected, 77 of which could be assigned to known genera\nand\nOverall, the number of bacteria (combination of R2A and BA growth) isolated from the ISS from all 24 samples ranged from 6.7 × 103 to 7.8 × 1010 CFU/m2\nSo quite high numbers of cultivatable bacteria (CFU = colony forming units, a measure of how many bacteria will grow per sampling), indeed as high as those found in a gram of soil, but very low species diversity compared to the soil.\nIt is still difficult to prove that this is a new species evolved strictly on the ISS, but it does seem logically likely that evolution will happen on the ISS, as it does anywhere that life is present (as far as we know).", "3" ], [ "There are several interesting components in soil:\n* The carbon content, mostly in the form of humic acids - a proxy for how well the soil an store nutrients and water and for wether there's a living soil microbiome (earthwormes etc.). Soil carbon is also removed by biological processes outside of special circumstances like peat foramtion. Carbon is added by decaying plant matter and other organic matter, like faeces of animal (wether natural or manure applied as fertilizer)\n* The macronutrient content, what we think of as fertilizer - usually N, P, K, (and to a lesser extent) S are considered macronutrients that plants need. There is also the question on how available those nutrients are. Macronutrients are added as fertilizer. Macronutrients that come as part of organic matter (e.g. N in proteines) must first be digested by something. This is why earthworms and the like are important. Macronutrients can be washed out and aer used by plants.\n* Micronutrients - trace elements, salts etc.", "1022" ], [ "that plants need. Again, it is important to understand that not so much the total amount in a given volume of earth is interesting but the amount actually available to a plant (Mg tied up in the middle of some rock won't help). I think these cycle like macronutrients, but the slow breakdown of sand and rock is also an important source. But this is a slow process. On intensivly used fields, these will be added in addition to fertilizer. This gives you a hint that the processes supplying micronutrients happen slowly.\nSo if you think of soil as the sum of these three categories you can look at how fast or slow each is replenished and used. FArmers will watch for the nutrient balances as well as for the carbon balance of their fields.\nHowever all of these influence each other, soil is really complex. While you can argue that soil is renewable since in some cases all three broad categories of stuff will be replenished eventually, IMO this misses the point how slowly this happens. It also misses the more important point that soil is not simply a mixture of stuff but ideally a living system where things happen.", "1022" ], [ "In short, being haploid or polyploid should not protect you from Selfish Genetic Elements (SGES).\nAlmost all eukaryotes are polyploid. Plants are the oft-cited example. Wheat, I believe, is hexaploid for example. Polyploid bacteria are the exceptions typically (if we consider ploidy to be of the whole genome). However, even in truly haploid bacteria, the genome in any given cell is usually actively being replicated, so some of the genes are actually present more than once.\nRegardless, replication and repair is an enormously well controlled and regulated process: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1479556/\nSGEs can take many forms depending on your definition and are ubiquitous in nature as far as we can tell.", "667" ], [ "Plasmids which harbour addiction factors, insertion elements, transposons, prophages etc are all technically SGEs. See here for a review: https://www.ncbi.nlm.nih.gov/pubmed/21227262\nI can't find any literature on SGEs in polyploidy directly, but it is well documented that bacteria harbour a considerable amount of selfish DNA - it seems likely that this will be the same if not worse in polyploidy. Plasmid detection is a difficult computational and experimental process (http://bioinformatics.oxfordjournals.org/content/early/2016/11/18/bioinformatics.btw651.full) but one of the hallmarks of plasmid sequences are typically addiction factors (a gene that the host cell must maintain in order to survive - usually an anti-toxin to neutralise a toxin present on a different DNA molecule) as well as phage genes.\nTo address a couple of things specifically:\nAs each copy replicates separately it would seem likely that spontaneous mutations would arise and over time\nThis is somewhat true, there is always minor variation in a population (else evolution wouldnt work!). Sometimes you'll find this is also the case in a single cell - but less often. All cells we have found so far have DNA replication and repair mechanisms - https://en.wikipedia.org/wiki/DNA_repair. The frequency of mutation in the genome is not directly linked to the amount of selfish elements though, making your second point contentious:\nThis seems like an ideal place for selfish copies to arise\nI agree with the premise of polyploidy probably inviting more SGEs (thinking specifically of IS elements and transposons here really), but not because of mutation - rather, just because there are more DNA molecules and sites present for those elements to incorporate into.", "667" ], [ "I can only offer a partial answer on the theoretical aspects. I don't know if you are familiar with the mid-90s papers by <PERSON> et al. (Otto & Goldstein,1992, Otto & Marks, 1996), but these are definately relevant to your question. They deal with the \"masking hypothesis\" of diploidy, i.e. that deleterious mutations can be masked by \"healthy\" alleles, and the trade-offs between diploidy (ploidy level), recombination rate and purging of deleterious alleles. Otto & Goldstein (1992) shows that recombination is essential for the evolution of diploidy, and without recombination haploids will \"win\" over diploids.\nOtto & Marks (1996) is a fairly comprehensive paper that builds on the previous one, and looks at how different mating systems interacts with recombination and purging to influence the evolution of ploidy levels. As a general results they predict a correlation between mating system and ploidy level, with sexual reproduction favoring diploidy while asexual reproduction favors haploidy. However, from what I can see after a quick re-read, there is nothing that prohibits asexually reproducing species to be diploid (and vice-versa) - see e.g. page 206 - and the paper includes a condition that must hold for diploids to invade in asexually reproducing or selfing populations. I have not followed this literature closely though, and I imagine that tracing recent papers that cite Otto & Marks (1996) can be useful to find further relevant studies.\nYou should also consider that ploidy levels can differ between sexes (e.g.", "882" ], [ "bees), which can lead to antagonistic selection which can influence ploidy evolution (see e.g. <PERSON> & <PERSON>, 2014).\nAs for the empirical evidence part, I do not have any good examples. However, I imagine that it can be extremely difficult to prove that a lineage have only reproduced asexually (or never asexually), since these things are hard to track in fossils. Also consider that it is common to have both sexual and asexual stages, and many species can have a long asexual diploid stage followed by a shorter sexual haploid stage. From what I know, this is the norm in e.g. algae (arguably a group of fairly \"basal\" taxa). However, I don't know what the ancestral state of algae was (i.e. if they became diploid before having a sexual stage).\nAs for the ancestral state of eukaryotes, there seems to be evidence that the ancestral state was in fact facultatively sexual (Dacks & Roger, 1999), which would invalidate your assumption. However, this is only based on a couple of quick literature searches on my part, and I am in no way an expert in this area. There are probably more recent studies on this topic as well. However, it is clear that you cannot blindly assume that eukaryotic haploid is ancestral.", "3" ], [ "The h2co3 content of unadulterated rain is 15 micromoles of H+/Kg at room temp. The pHBC of average field soil from a 3000km transect in asia varied from 10 to 188 - mmol-kg-ph unit... from 40 localities. This other research found soil values of 45-1000 pHBC.", "362" ], [ "https://www.science.gov/topicpages/s/spiked+soil+samples.html\nThat means that H2CO3 would affect arid meadow soil by 0.08 to 1.0 pH points if 1kg of water reacted completely with 1kg soil in a sealed environment. And 0.33 to 0.015 pH points for the referenced research.\nHowever, if you boil the water, the gases expand and leave the water even prior to boiling point, which can be seen as bubbles previous to 100'C, boiled water error becomes 0.2 to 0.003 pH points. This is the only ref i can find:\nhttps://www.engineeringtoolbox.com/docs/documents/1000/solubility_CO_water.png\nttps://www-engineeringtoolbox-com.cdn.ampproject.org/ii/w1200/s/www.engineeringtoolbox.com/docs/documents/1148/solubility-co2-water.png\nThat means that if you have unadulterated rainwater at pH 5.5, and you boil it and jar it, you will have water with a pH near 7 after sealing and cooling.\nPure water is not natural or biological and it is aggressive to get to equilibrium. Upon contact with the atmosphere, it will immediately begin absorbing CO2 and the pH will drop and settle in at about 5.5 after about two hours.\nCarbonic acidification is a background effect of the athmosphere aerated soil and rain to similar degrees.\nStrong acid - pKa < 2 Weak acid - 7 > pKa > 2 Weak base - 10 >pKa > 7 Strong base- pKa > 10\noxalic acid and citric acid have a pKa in the range of 1 to 3, they are fairly strong, whereas CO2 has a pKa of about 6.4.\nIf your rainwater has a pH below 5.3, something is wrong with it and if the rainwater is around 5.5, it's nearly the same as distilled water.\nI micromole of HCl rects completely and gives distilled water a pH of 6, whereas 1 umol of CO2 causes [a pH of 6,997][6], because only 0.3% of it converts to H2CO3.\n[6]: https://books.google.fr/books?id=yRMgYc-8mTIC&pg=PA124&lpg=PA124&dq=hcl%20micromole%20co2%20distilled%20water%20concentration&source=bl&ots=OFKb4CB3MI&sig=ACfU3U0a1XQ_GSIZ5E-nj7JgPsaeDv7SbA&hl=en&sa=X&ved=2ahUKEwib-vuMkc_hAhVEThoKHYIcDtQQ6AEwCXoECFAQAQ#v=onepage&q=hcl%20micromole%20co2%20distilled%20water%20concentrationhcl&f=false", "979" ], [ "Life organisms\nEarth examples and liquid water\nFirst of all within the ranges given, at temperatures lower than 150 °C and pressures greater than 10 bar water is liquid. Which also means that there is no runaway greenhouse effect under those conditions. Among the living organisms that live and reproduce in those conditions there are the following:\n* Methanopyrus kandleri lives optimally at 105 °C (up to 122°C) and it was found also underwater at 200 bar. It can consume CO2 and H2 to produce methane(CH4).\n* Pyrobaculum islandicum lives best at 100 °C (up to 103°C). It can survive with only elemental sulfur, CO2 and H2 while acting as the producer of organic matter that the other living being may need.\n* Pyrolobus fumari lives best at 106°C (up to 113°C) and was also found underwater at 370 bar. Among the many ways, it can live by consuming O2 and H2.\n* Geogemma barossii aka. Strain 121 lives best at 103°C (up to 130°C) and it was found also underwater at 243 bar. It survives by using iron instead of oxygen.\n* Pyrococcus furiosus lives best at 100°C (up to 103°C-105°C). It can generate H2, but O2 is toxic to it. In its presence it tries to convert it into water.\nCarbon cycle and ozone\nAssuming a way of producing O2 from water (which will be discussed later) the presence of O2 in the air would transform the CH4 produced by the Methanopyrus kandleri in formaldehyde(HCHO). This would react with O2 to produce formic acid, which readily decomposes into H2O + CO in the presence of sulfuric acid, which is present in the upper clouds of Venus.\nFor the ozone you mostly need only O2 due to the ozone-oxygen cycle.\nOxygen cycle\nAs per the missing production O2, this would be what plants usually do.", "279" ], [ "This wikipedia paragraph shows how increasing the temperature is either indifferent or improves the photosynthesis, but this may not apply to temperatures a bit over 100°C.\nThere are some like the Chloroflexus aurantiacus that are able to do photosynthesis using bacteriochlorophyll instead of chlorophyll and grow at 70°C, but they don't produce O2 (this due to using bacteriochlorophyll). Others like Cab. thermophilum are able to use chlorophyll at 66°C, but they consumes O2 instead of producing it.\nEven if I didn't found any O2 producing organism that lives at over 100°C, it's important to notice how such an environment is rather scarce on earth, which makes the few known cases have a rather low statistical relevance. There could be an alternative and possible evolution path where those exist, but it just didn't happen. From the data riported the existence of such a being seems plausible. On the other hand if there isn't such a being then the requested planet can't exist (no oxygen-producing airborne life at those temperatures).\nEnvironment planet-wise\nRequired differences from Venus\nFirst of all that planet should have a magnetic field like earth to reduce the loss of oxygen and hydrogen due to the solar wind, as they are both needed for life. Having a thermosphere is not a problem as both Earth and Venus have it.\nAdditionally a day duration more similar to the one on earth would allow for a more even temperature which helps (together with the CO2 that on the surface is a supercritical fluid with a good heat conduction) the organisms have the temperatures more near the mean of 100°C (131°C and they all die). This would have the effect of changing the wind circulation into one more earth-like.\nConsequences on sulfur\nIn a planet with an atmosphere composition like the one of Venus, the surface pressure would be around 90 bar, which is perfectly within range. As per the temperature, it'd surely be higher than the one of a planet like earth, but that would still depend on its distance from the sun. Just put it much further away and you'd get the desired surface temperature. This has also the effect of preventing the formation of the clouds as the sulfuric acid cycle needs a surface temperature of at least 300°C (which is not there) to regenerate the clouds from the acid rain like on Venus.\nThe result would make all the sulfuric acid stay mostly on the surface and a big reduction in SO2 content in the atmosphere, with clouds being created through evaporation like on earth. It's also worth notice how the surface temperature of 100°C is at 33% between the melting and boiling point of sulfuric acid, while the earth average of the surface sea is 16.", "943" ] ]

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[ [ "I'm wondering how you expect a Giant to be as well armored as a battleship. The Giant would barely be able to move around if only because having a meter of armor around their joints would impede them too much. Also Naval Guns tend to be long, the Iowa class guns were 20m in length so they would have to use a shorter version which would limit their projectile velocity and thus effectiveness. Even tank guns are a sizeable portion of the Giant's length, making these guns unwieldly. Even if you assume a Giant can somehow carry all that despite the square-cube law he's going to be rather burdened by that. It's far more likely he's carrying tank armor and tank guns, although I would think they would be more like AFV's than tanks.\nAnyways, reasons to use infantry next to your Giants with the unlikely armor+armaments:\n* Scouts\n* Communication (with radio's and such)\n* Repairing and maintaining gear of the Giant\n* Anti-armor support with missiles and such. Tanks would still be a threat despite battleship armor because of the squishy Giant inside.", "347" ], [ "A HESH shell would do squat to a battleship, but a shockwave going through the brain/lung/bloodvessles is going to wreak havoc on the Giant and probably kill him.\n* Anti-Giant support. Whether using armor-piercing or a superheated jet of a HEAT round or just HESH weapons, the use of infantry-based AT weapons are going to be effective against the joints of the Giant where the material has to move with the joints and can't be as thick. This can incapacitate Giants if not kill them with a shot to the neck for example.\n* Soft terrain traversal/terrain scouts. These Giants even without armor will weigh well over 100 tons, with armor it's likely they'll exceed 500 tons (because that armor is going to weigh more than the Giant). This isn't going to be nice travel when you hit soft ground where they'll likely sag into the ground, get stuck and starve unless some heavy-duty cranes get brought in. Cranes that just like the Giant need to be careful with what ground they stand on even before they lift a 16m Giant in full battleship armor.\n* Building capture. You can't capture buildings with tanks, and you can't capture buildings with Giants.", "347" ], [ "You Don't Want Walls, You Want Bait\nSure you want to have a 20ft high steel wall with a 100ft wide 40ft deep trench facing the exclusion zone to keep out the low-grade Kaiju. Or at least a fence to ward off humans who accidentally stray to far west. You might even want some strategically placed strongpoints for specialist troops/machines to sally from in the event a mid-grade Kaiju gets frisky. But what you REALLY want (Given that Godzilla is essentially unkillable and the high-end kaiju probably only slightly less invulnerable) is a way to get the Tier 1 Kaiju to GO ANOTHER WAY.\nSo you want Bait. Tunnels under your lines that stretch deep into the exclusion zone that are far to small for any sort of Kaiju, but which on short notice can pop out something that interests the Kaiju. The Bait then heads screaming in the direction opposite of your walls/civilian centers. If you want added spice, maybe have it head towards another known Kaiju in the hopes the monsters will kill each other off. These Bait machines also need to have SOME sort of Kaiju nourishment, so they don't end up getting viewed as inedible and eventually ignored.\nWhy tunnel-deployed? You don't want the Kaiju to view the Wall/end of the zone as a source of food. Thus you need some sort of underground system where the Bait inevitably appears BEHIND any Kaiju that hits X location. You'd want literally thousands of such tunnels so the appearance of Bait could be deemed random and you don't just have Kaiju \"camping\" the tunnel exits. For the same reason they need to be as hidden as possible. This also means that there needs to be essentially wasteland between where the bait arrives and the wall. So the Kaiju thinks \"man that looks like a terrible place to find dinner\" and makes going towards the Wall as unappealing as possible. So they get to the edge of the wasteland, a tasty snack pops up behind them, and they think \"oh yeah, there's obviously better hunting in the West.\"\nWhat Nourishment? That depends on the type of Kaiju. Worst-case scenario is they're manned craft. And lets face it, they are because \"Kaiju bait pilot\" would be a HELL of a main character.", "121" ], [ "Plus who knows how good your radio/satellite comms are. I'm envisioning some sort of ATV/mech/skimmer (tech-level depending) that carries a human crewman or two and a couple cows or a few tons of meat or radioactive elements/whateverelse a Kaiju feeds on in your universe.\nThe Plan Ensign <PERSON> is a KRV (Kaiju Redirection Vehcile) pilot, and it's his shift at Bastion 12 when a Primary Level Kaiju crosses within 50 miles of The Wall. Bastion 12 goes to Alert and Ensign <PERSON> mans his KRV and prays. at 40 miles to the wall the Kaiju officially enters the Redirection Zone and Ensign <PERSON>'s KRV is launched. Tactical command has set up <PERSON>'s KRV to appear half a mile to the Northwest of the Kaiju. The KRV appears, and sends up various flares/sirens/look-at-me devices. The Kaiju, naturally, turns. It sees the KRV, senses the meat/radioactivity/whatever inside, and pursues. Ensign <PERSON> now plays the dangerous game of trying to stay in front of the Kaiju and unkilled for either A: as long as possible, or B: until he reaches some arbitrary distance from the Wall far enough away that the Kaiju won't just turn around and be back in an hour. The chase might last days, it might last hours. Hell it might take weeks! (No idea on your Kaiju speed.) Eventually though the jig is up. <PERSON> ejects. The pod punches him clear of the Kaiju, who pursues the KRV, kills it, and feeds. Ensign <PERSON> now must face the treacherous Exclusion Zone and potentially other Kaiju to return home, and/or <PERSON> is killed by the Kaiju and his family gets a \"Deeply Regrets\" telegram.\n(Sidenote: you could also have tunnels like 200 miles away where KRVs could dive into and escape Kaiju, but that's a whole other problem of \"do the Kaiju dig after it\" \"do the Kaiju now 'camp\" the escape holes\" etc. etc. running-hopefully-ejecting-hike-back seems like the best of bad options to me at this point.)\nYou could also have some sort of airborne recovery teams to rescue ejected KRV pilots.", "837" ], [ "Nothing Changes... if you go back far enough\nIn premodern battles strong formations, which don't break are what everyone wants. - This is not universally true by any means. Nor is it universally true that forces which fought in such a fashion were automatically superior to those that did not. (Looking at you, Vikings-in-North-America and Crassus' Legions)\nInstead what you traditionally had were raids, ambushes, and the occasional \"Pitched battle\" which involved warriors exchanging ranged fire (javelins, arrows, what-have-you) at roughly 2/3 the maximum distance of their chosen weapon in a loose formation. Close combat weapons were (again, usually) used only in pursuit of fleeing foes, most of whom got away. If you want the details of the whys and whyfores I suggest War Before Civilization but I think for your setting two reasons trump the others:\n1: Raids and Ambushes were more effective. It's WAAAAAY safer (for the attacker) to burn down a village at night and spear people fleeing burning houses/ambush a lone hunter than fight in a pitched battle.\n2: Pitched battles were un-sustainability lethal for population size.\nYour battle-mages will mean these two qualities, especially the second one, are still true even after your societies start being able to have larger populations.", "523" ], [ "Any attempt at \"ganging up\" can be countered by one wizard shooting one fireball, nobody'll risk it. So battles will stay at what you might call a \"large skirmish\" style fight. Because of the increased lethality, ambushes and raids will still be the preferred method of warfare. After all, 15 guys, 2 of them mages, can do as much or more damage sneaking around and launching a wall-breaking fireball followed by house-destroying fireballs in the middle of the night as 1,000 infantry and accouterments can besieging a place for a year.\nSo what you'd actually end up having is battle-mage societies adopting \"primitive\" style warfare as a matter of course, and only those non-magic-using \"Savages\" will be stupid enough to actually stand shoulder-to-shoulder in a fight. Your system makes mass-battles far less likely in any event, as small groups can do massive damage to societies on their own. So instead of one large army maneuvering against an opposing large army and finally a battle/siege takes place, you'll have dozens or hundreds of small groups raiding into enemy territory trying to annihilate similar groups in ambushes or destroy settlements.\nI should point out that the \"primitive\" style of warfare I described above is actually MORE deadly than modern war as a % of population, let alone other types of ancient warfare. By orders of magnitude. War Before Civilization did the math, and turns out you are more likely to die by warfare in any given year as, say, a Native American of almost any tribe we have a reliable record for (pre or post Europeans) than as a Russian OR German 1914-1945, or a Frenchman during the Napoleonic wars. So even though your \"pitched battles\" are rarer and might LOOK less deadly than two pike phalanxes crashing into each other, in reality the actual war will be wildly more devastating.", "523" ], [ "Would a warhorse allow its rider to approach a Dragon at all?\nWould a horse (trained or otherwise) not be wholly spooked by a Dragon merely flying overhead, even more so trying to enter combat with it or just trying to approach it under any circumstances?\nWhat I understand of predator and prey creatures suggests that something that massive and formidable would radiate major predator vibes which would cause most creatures to cower or flee. Yet, I have only seen knights and other heroic character types depicted as approaching and even fighting Dragons without regard for or consequence from their mount's will.\nMost particularly, I am wondering about after such a beast is slain. Wouldn't a horse, even a trained warhorse, refuse to approach something that huge/dangerous even after it's dead?\nI am trying to troubleshoot a scene where a unit of mounted characters need to approach a felled Dragon (one they did not battle) under a time constraint and I need to know if they would be forced to dismount and approach on foot (slowing them down) to get where they need to go. Of note: these horses, though battle capable, have not encountered Dragons before - they do not have either genetic or actual memory with which to comprehend this with.", "160" ], [ "I have considered that even if they had blinders on, this would not help keep them calm because during approach that giant form would be directly ahead of them and not to either side covered by blinders.\nIs it even possible to train a horse to keep its wits around a massive apex predator under any circumstances?\nSince Dragons imply magic exists in a setting they exist in, I can concede magic being one possible solution to maintain calm utilizable in a well-arranged military scenario. Magic-capable units could cast some sort of calming spell to keep mounts from panicking, but, that requires some of the best defensive/offensive resources to be rerouted when likely needed for offensive/defensive tasks. I also cannot reliably expect a magic-enabled individual specifically capable of casting such a calming spell to always be around. What happens to the horses of the local town guard during an unexpected Dragon attack?", "358" ], [ "Assuming WWI or 2-ish technology: just use the mechanisms they already used and had for these types of weapons:\nTrip Wires or Electronic fuses\nTrip wires were commonly used with mines as an activation mechanism. This concept works with a hoover craft as well. The disadvantage of trip wire was it was easier to see than a standard pressure sensor and as the location of the \"trip wire\" might need to be altered (raised) this disadvantage would increase. However, its still possible as one could disguise them in the barbed wire which littered the \"deadman's land\" fields that trench warefare used. I would also set this up as a daisy chain of mines to improve the chances of disabling or even just hitting this quick vehicle.\nOn a similar note, which would be more accurate but also more dangerous for troops.", "477" ], [ "You could set up a electronic fuse (think the old TNT \"plunger\") which a solider would trigger once the vehicle was over the mines.\nRadio Activated Mines\nThis became more of an issue in modern warefare (and with IDEs) but radio activated mines are a real thing. The radio technology of WWI required pretty big comm equipment which was usually transported by horse or mule1 but, as trench warefare was largely static, it is conceivable that a few stations could be setup which allow for activating a mine. The range and low development of radio technology would make these much less reliable than fuses but the ability to be farther away and not have to disguise wires themselves certainly makes this an interesting tactical option.\nMagnetic Mines\nThese were actually developed during WWI but did not see much action until WWII (and then only as a Naval weapon)2. However, if these hovercraft are seen as a potent threat and weapon it makes sense that this weapons development would be accelerated and a ground-based version developed.\n1: \"Golden Age of Radio in the US\", Radio on the Frontlines exhibition. Digital Public Library of America.\n2: <PERSON>, <PERSON>, \"Naval Weapons of World War Two\" (London, UK: Conway Maritime Press, 1985)", "477" ], [ "Depends on what \"Annex\" Means\nI think Denver would be the logical capital for a United States faced with the situation you describe. However I think if anything that grants impetus for it to NOT be the national capital for the USNA.\nHistorically both Washington D.C. (US Capital) and Canberra (Capital of Australia) were created out of whole cloth in part to unify the burgeoning nation they would be the capital of. Both were situated more-or-less in the geographical center of their nation at the time. Canberra was actually created on the exact midpoint between two competing claims (Melbourne and Sidney). Even given the destruction of the previous capitals and utter lawlessness in Canada, I can't imagine the Canadians would be thrilled by a Union. Likewise I can't imagine the US Army is actively conquering Canada when Kaiju are wrecking whole swaths of the US. So I'm imagining more of a \"mostly peaceful\" marriage-by-necessity USNA rather than some sort of US military campaign or active begging on the part of the Canadians.\nIf the above is true, there would be a LOT of pressure on the Canadians to be distinctive members of the USNA. I would imagine that if Denver became the New US Capital (and there are many reasons why it should be in your timeline) The USNA National Capital would NOT be Denver. It's far away from Canada, it's already the US Capital/a US State Capital, and Canadians are already going to be a minority.", "454" ], [ "Allow the nation to be ruled from the US Capital and Canada isn't a thing anymore in any respect. It just becomes a scarecly-populated backwater of the US, regardless of the name change. Likewise American pride/politics would likely shy away at ANY Canadian city being the USNA Capital.\nA compromise bet would be to found a city on the border that straddles the two nations (much like Canberra and to a lesser extend D.C.) to show \"unity\" and is something that doesn't have the baggage of already being a state/national capital. However, in the middle of fighting a massive Kaiju invasion with presumably millions dead that seems too difficult/wasteful even for politicians. So instead I would imagine some large town or minor city close to the border on the US side would be used as the official USNA capital. There are a ton of contenders like Sault Ste. Marie (A US AND Canadian town right across from each other in Michigan/Ontario), but without a map of your <PERSON>-devastated regions I can't comment on what town would be best. There are better choices but those are all on the east/west coast and I assume are destroyed in your timeline.\nTL/DR: Your choice of Denver makes perfect military and political sense for the US. But for the USNA Canada would likely have serious political problems with it. A city on/near the old border would be the likely compromise position.", "454" ], [ "Forging with Geothermal Heat: Possible Alternative to Fire in Alien Species' Technological Progression?\nA world idea I'm playing with for a sci-fi idea I'm working on has an atmosphere similar to the composition of Earth's Atmosphere during the Carboniferous Period: Lots of Oxygen, so while a Human or a creature with similar breathing needs could probably breathe fine, that also means everything is extremely flammable. As this world is also relatively similar to Carboniferous Earth in that a large percentage of its overall landmass is covered in fairly dense forests, and while it's fairly damp and even downright swampy in many of these places, the higher oxygen content means that even damp things can sometimes Ignite.\nThe major sapient species on this world, as a result, are obviously fairly wary of Fire Hazards and Fire In General; as a result, contrary to the evolution of technological progression in humans (which most sources say Began In Earnest with Early Man learning to harness fire), they likely wouldn't be able to harness and utilize Fire safely until much later in their civilization's development, when they would have a means to contain it and prevent its spread on a large scale. Even then, if they developed a means of harnessing fire At All after so long without it, it would probably be used sparingly and Very Carefully, limiting or at least slowing experimentation.\nI have worked out a potential alternative: natural hot springs and other Geothermal activity can be used in things like cooking and other complex food preparation, and the steam could probably be funneled or channeled to heat dwellings and power relatively simple machines, which in turn could probably open up new options for developing other technologies.", "922" ], [ "They also behave and structure themselves in a fashion similar to an ant colony, and as a result already practice various forms of agriculture (similar to the practice of many irl ant species that cultivate edible fungus and raise/\"pasture\" aphids for both nutrient-rich secretions and, eventually, meat) that would likely be aided by, and be an evolutionary pressure in favor of, the development of tools.\nThe one dilemma I have is this: while they can compensate for/find different paths to the development of various other technologies that seem to have shaped the development of human civilization, their aversion to/difficulty working with Fire is going to make things like Metallurgy difficult. While they were not initially a space-faring race, and only became aware of interplanetary travel when briefly invaded and occupied by a military power from another world before fighting them off and regaining independence later, they have likely seen the benefit of joining the intergalactic community on their own terms and are going to try and turn their hand to creating spacecraft, which will likely involve manufacturing things like metal and glass and plastic components (or, you know, rough equivalents) on a large scale. While it's possible that they borrowed new technology and ideas from their former oppressors, I was wondering how far along they could get in terms of Smelting Technology without outside influence, and how big of a jump that's going to be for them to make.\nSo, my question is this: if they have some means of funneling and redistributing steam for things like Heating Their Nests and warming water (probably by digging tunnels or boring out large tree trunks for makeshift piping), could they somehow... Collect that heat, and use it to heat up something akin to a Kiln or Forge in function? Or is this something that, as far as we know, can only be accomplished with fire? Alternatively, what methods could be used to control the spread of fire enough to allow them a little more experimentation, given the higher amount of oxygen and increased likelihood and danger of accidental fire-starting?", "197" ], [ "Could a Giant Earth planet have lower gravity than Earth?\nI'm writing a neo-pulp adventure and one of the planets that appears needs to have the following characteristics:\n* Is populated by giant non-sentient non-humanoid insect-like aliens, some from the sizes of cattle but some from the size of a Boeing 747. Some of the bigger creatures should be able to fly.\n* The atmosphere is very thick and most of the planet is very jungle-like like a rain forest.\n* The flora is not so Earth-like, there are no trees, but plants with flowers can grow taller than redwoods.\n* There will be one type of spider-like creature that creates something similar to a spider web but strong enough to capture a small flying vehicle. Thus this creature should be able climb plants.\nNow I was thinking that for many of these characteristics it should have lower gravity however I'm not sure if is physically possible for a rocky planet some N times Earth's size to have lower gravity.", "922" ], [ "I know that a planet's gravity has to do also with density and not only size, but again, not sure if a rocky planet can not be dense enough to have lower gravity than Earth. Another possibility is to make the opposite, a planet with high gravity with its fauna adapted to it, however in that case I doubt flight will be possible.\nKeep in mind that: * Earthlings (as I'm not using the term human) are not going to stay there for much longer, just a couple of days, weeks at most. * If Gravity is higher than Earth it should not crushed humans and human-size aliens that arrive there, but can cause some discomfort.\n* Technically is not necessary for it to be a super Earth, even an Earth-size planet is still huge but if possible to keep this will be more fun. * Is preferable that the atmosphere is human-breathable.\nThanks in advance.\nPD: Is a neo-Pulp novel so is certainly not hard sci-fi, science doesn't have to be rigorous (although some scientific accuracy doesn't hurt anyone) but the point is it's soft sci-fi as long as avoids magic or fantasy explanations will be enough.", "947" ] ]

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[ [ "Poland’s artistic and architectural contributions remembered in 2019 commemoration of the 1963 Skopje earthquake · Global Voices\nMonument to the victims of the 1963 earthquake in Skopje. Photo by GV, CC BY.\nEvery July 26, citizens of Skopje, the capital of North Macedonia, remember the earthquake that shook the city in 1963, and express gratitude for the international action that helped rebuild the city. The 6.1-magnitude earthquake reduced much of the city to rubble, killing 1,100 people, leaving over 200,000 homeless and thousands suffering from serious injuries. At the time, Skopje was the capital of the Socialist Republic of Macedonia, a constituent state within federative Yugoslavia.\nA massive humanitarian effort to help the survivors and rebuild the city mobilized all the republics of the Yugoslav federation as well as the international community, which at the time was otherwise divided due to the Cold War. US President <PERSON> personally intervened to cut through the red tape and expedite US humanitarian aid, while USSR PM <PERSON> visited the ruined city with Yugoslav leader <PERSON>. Within days of the disaster, American and Soviet soldiers flew in to work side by side to provide humanitarian aid.\nArchitects, engineers, and construction workers from across the world worked under auspices of UN to rebuild the city into a model modernist metropolis. As a result, Skopje was nicknamed ‘the city of international solidarity.’ The UN's plan for the city was only partially implemented, but many of the brutalist-style buildings from the era remain today, and many streets still carry the names of the countries, cities or individuals who helped, including Algiers, Mexico and Prague.\nRediscovering Poland's artistic contribution\nThis year's commemoration of the earthquake is enhanced by an exhibition in Krakow, Poland that displays the artworks donated by Polish artists at the time as part of the relief effort.\nPoland was a major contributor to the disaster recovery efforts, harnessing the experience gained through the reconstruction of cities like Warsaw which were devastated during World War II. Top Polish architects helped build the iconic Museum of Modern Art, and there's still a street bearing the name of architect <PERSON>.\nAfter Ambassador <PERSON> arrived in Skopje in 2014 as Poland's highest diplomatic representative, he and his wife <PERSON> researched the Polish legacy and discovered, at Skopje's Museum of Modern Art, a unique collection of 20th-century Polish art donated by the artists after the earthquake as a gesture of solidarity. This ‘time capsule’ had been virtually forgotten in Poland. Over time, the couple uncovered many other cultural links, leading to further public discourse through exhibitions and publishing of books and other works. Some of that work is documented in the short film “Skopje. The Art of Solidarity.”\nIn an email to Global Voices, Mrs.", "739" ], [ "<PERSON> and Ambassador <PERSON> explained the drive behind their efforts that have connected countries and time periods:\n<PERSON> and <PERSON> during his tenure as Polish ambassador to Macedonia. Courtesy photo, used with permission.\nSkopje must look familiar to people who have lived or spent some time in Warsaw. Destroyed and rebuilt. The same mix of styles, a similar urban space. And, on top of that, scattered around the two cities are the “islands” of modernist architecture, which we, Poles, began to rediscover just a few years ago. Post-war architecture (after 1945) has become a fashionable topic in Poland – redefined, mainly by young people. Today, some of these buildings, until recently abandoned and neglected, are considered examples of functionality and elegance. They are receiving a second life, and with that comes their new function: cafes, galleries, centers of culture and urban activity.\nThe 1963 earthquake that destroyed Skopje moved the whole world, including Poles, whose great engagement should not be surprising. Only 18 years before WWII had ended, leaving Warsaw totally destroyed. The rebuilding of the Polish capital started immediately, with great devotion and enthusiasm.\nWe are too young to remember the emotions accompanying the gestures of solidarity shown by Poles in Skopje, but we met people who told us about it. In their memories Skopje, the city that attracted professionals from all around the world, was cosmopolitan, open and modern. And it was in that spirit that the city was created anew after the earthquake.\nWe, thanks to our Warsaw experience, have been able to find this spirit in today's Skopje.", "739" ], [ "North Macedonia’s <PERSON>, the prime minister who ‘has done the most to serve his country’ · Global Voices\n<PERSON> leaving the official building of the government of the Republic of North Macedonia. Photo by Government of Republic of North Macedonia, Public Domain.\nAfter having announced his decision on October 31, <PERSON> submitted his resignation as North Macedonia’s prime minister on December 22, thus triggering the constitutional procedures for the resignation of the prime minister and government, and assignment of the mandate to form a new government. A day later, the parliament confirmed his resignation at a plenary session.\nIn the text of his resignation published on the government website, <PERSON> noted he undertook this “logical step” as a way to “accept responsibility” for his party's poor results at the local elections in October. He also resigned as leader of the ruling party, announcing his retirement from politics. After <PERSON>'s resignation, President <PERSON> gave the mandate to the new representative of the established parliamentary majority to form a government.\nWhile we are looking at the constitutional procedures and assessing the leadership of <PERSON>, it is worthwhile mentioning that he is the first prime minister in the history of North Macedonia to resign while his party was still in power (Actually, <PERSON>, another Social Democrat, resigned as party leader and prime minister in 2004, but this was to allow him to seek election as president of the country.)\n<PERSON> was a very interesting politician and one who had attracted the public eye. He was first elected as party leader eight years ago as a part of a team. He was the candidate for leader, while the current minister of defense, <PERSON>, was the candidate to be his deputy. The duo led the party during the political crisis of the wiretapping revelations, the negotiations of the Przhino Accords and the early parliamentary elections in 2016. <PERSON>'s election promises were to restore democracy and freedom, bring the country into NATO and the EU, and improve the quality of life of its people.\n<PERSON> and his VMRO-DPMNE had a strong hold on the government and institutions; it was an authoritarian regime that the European Commission described as a captured state.", "363" ], [ "For every citizen who had lived a day in such fear, or the nearly 20,000 whose phones were wiretapped, bringing back democracy and freedom was of utmost importance. On this, his primary promise to make North Macedonia more democratic and freer, he delivered the most.\nAfter it became clear, in January 2017, that <PERSON> was unable to form a government, his party orchestrated persecution against civil society and activists, with a long list for “execution” containing up to 170 most prominent political and civic leaders and opinion-makers. He disallowed any transfer of power and supported the storming of parliament on April 27, 2017. The angry mob attacked and beat scores of people, effectively making <PERSON> pay with his own blood to be elected as prime minister.\nHaving witnessed how <PERSON> used ethnic tensions to raise the fear of ethnic Macedonians, <PERSON> realized that this fear could only be decreased with further unification in society and if the country’s safety and security were guaranteed. The best guarantee for that was unification under the same goals as NATO and EU Accession, and genuine inter-ethnic integration, which led to the new government policy of “One Society for All.” He further supported this by speaking to all citizens and ethnic groups, presenting candidates for mayors in traditionally Albanian municipalities, while promoting politicians, Social Democrats, representing minority ethnic groups to high posts in the party and in the government. It was in many aspects a pioneering approach for North Macedonia and showed <PERSON>'s ability to see the bigger picture.\nHis political instinct as opposition leader to establish friendships and build alliances was successfully transformed into a vision to which he dedicated his first three years as prime minister, resolving the open issues of the country. It was lucky for him that this vision was met halfway by former Greek Prime Minister <PERSON>. The Prespa Accord was an effective resolution of the name issue with Greece, but it was also the foundation for North Macedonia to accede to NATO and fulfill one of its national priorities almost three decades after its independence.\n<PERSON>'s first attempt at friendship building was with Bulgaria and produced the treaty on friendship, good neighborliness and cooperation, which he signed with his Bulgarian counterpart <PERSON> on August 1, 2017. The Friendship Agreement speeded up the strengthening of bilateral relations in the period from the signing of the agreement until mid-2019 and facilitated trade, but it has yet to bear fruit, as Bulgaria is currently blocking the EU Accession of North Macedonia.\nOne final attempt at friendship building was tied to his faith and religious background.", "409" ], [ "Macedonian Students’ Photo Project Reveals Scenes From WWI, Then and Now · Global Voices\nPhoto of two children from 1917 Bitola and the same street along river Dragor in 2017. One of them is wearing a French army helmet. Used with permission.\nA group of high school students from the southern Macedonian town of Bitola is using photo collages to revive local memories of the First World War.\nA hundred years ago, Macedonia was part of the so-called Macedonian Front, also known as Salonica Front (after Thessaloniki) or Eastern Front in French (Front d'Orient), which is roughly along the current border with Greece. From March to October 1917, the Allied-held city of Bitola was devastated by 13 major artillery bombardments by the Central Powers, which included the use of poison gas.\nFast forward to 2017, high school students who participated in a project enabling kids from several cities to learn more about the period prepared an exhibition of photographs of Bitola then and now. They juxtaposed the photos of their city taken in 1917 or 1918 with the actual sites today.\nThe resulting photographs show how Bitola has changed in 100 years. They drew much social media attention after some of them were published on Bored Panda.\nBesides photographs, another type of “memento” from this historic period are unexploded ordnance – grenades, cannon shells and bombs which still litter the area. Residents continue to unearth such dangerous artifacts at least once a year.\nDisplaying of collages combining old photos in new context. Photo by ALDA – Skopje, used with permission.\nThe overall project included diverse student groups from Skopje, Tetovo, Strumica and <PERSON>, who together with their peers in Bitola participated in workshops based on peace-building methodology and explored the old battlegrounds through field visits. Each group then chose different methods to show what they've learned, making a short video, interactive map, and a diary of a soldier.\nTeaching young people about the horrors experienced by ordinary people in previous wars enables them to become active agents in preventing new conflicts. This is especially important at a time when nationalists continue to open the old wounds from recent Balkan wars, including those from the 2001 armed conflict in Macedonia, to mobilize political support.\nPhotograph showing Allied soldiers marching along Bitola main street a hundred years ago. Used with permission.\nGlobal Voices received permission to republish the photographs thanks to the Association of Local Democracy Agencies (ALDA) – Skopje, which implemented the project with the aid of the British Embassy in Skopje. The participants of the project include Professor <PERSON> and students <PERSON>, <PERSON>, <PERSON>, <PERSON>, <PERSON>, and <PERSON>.\nCitizens of Bitola are proud of preserving some of the old buildings, built during the time when their city was a provincial capital of the Ottoman Empire and seat of foreign consuls.", "739" ], [ "The pictured building serves as Primary Music School. Used with permission.\nThen and now. How the Army Club, built in 1911, looked in 1917 and today, through two photos. Used with permission.\nThe companion piece of the above photo, showing the other side of the street. Used with permission.\nSome of the damaged buildings during the 1917 bombardments had been repaired and are still standing today. Used with permission.\nA scene from the Bitola Old Bazaar. Used with permission.\nOfficers in British and Serbian uniforms walking on Shirok Sokak, the main shopping street in Bitola. Used with permission.\nA preserved house in Bitola. Used with permission.\nA house which brandished an UK flag a hundred years ago, possibly used by the army. Used with permission.\nChildren taking a photo in front of St. Dimitri church in Bitola. Used with permission.\nSerbian officers driving through Bitola centre alongside Dragor river. Used with permission.", "739" ], [ "By gathering knowledge, volunteers step in to save and revive the Macedonian music industry · Global Voices\n<PERSON>. Courtesy photo, used with permission.\nGathering over 30,000 songs published in the previous 69 years, a group of enthusiasts has created the VBU Music Registry, the biggest public record database documenting music production from North Macedonia and music published by local artists abroad.\nSo far, volunteers of this nonprofit initiative have created a digitized archive covering over 2000 albums, 1000 EPs and over 5000 singles by over 11,000 songwriters, composers and performers, creating free online portfolios for them. The registry was founded in 2013 by <PERSON>, IT developer and entrepreneur, who, in the 1990s, was a participant in the nascent electronic music scene in Skopje, as composer and producer.\nGlobal Voices spoke to <PERSON> about the challenges of digital activism in the area of culture in North Macedonia, the state of the music industry and the negative influence of COVID-19 on its business model.\nGlobal Voices (GV): Why did you create the VBU Music Registry?\n<PERSON> (VB): I started the VBU Music Registry because of my love of music, which is a wholly romantic notion. I was motivated by a kind of revolt against the generally demeaning attitude against domestic music when compared to imported products, declining societal values and the lack of media freedoms. During that period (2012-2013) I resented the fact that mainstream media only aired music deemed politically suitable, while artists who were not close to the then-government were ignored or censored.\nMy intent was to create a media that will show the domestic public that the music promoted by mainstream media is not the best, and most importantly, not the only music created in the country. I wanted to showcase its cultural treasures, channeling my anger against damaging and corruptive practices.\nGV: VBU Music Registry fills wide information gaps in the Macedonian public sphere, enabling citizens to access information unavailable via commercial or academic sources. What experiences can you single out?\nVB: Our biggest success is creating a community of individual enthusiasts united via self-governing model and creating new value by accumulating public knowledge about the music production in the country. At a broader level, this team provides services to a wide community of musicians and fans numbering around three thousand people. This results in a continuous, albeit slow, growth of public attention about domestic music.\nAt the moment, our biggest challenges are technical, from automating the data input about music publications to integration with online music streaming and download services.\nGeographically dispersed core team of VBU Music Registry rarely meets in face to face, and do all of their communication online (several team members are not in the photo). Courtesy photo, used with permission.\n<PERSON>: How has the experience of starting and leading this initiative affected your life?\n<PERSON>: I personally find the work on VBU Music Registry very fulfilling.", "363" ], [ "This inner feeling of doing something good positively affects both my personal and professional life. The biggest benefit of doing voluntary and nonprofit activity is enabling me to meet a lot of good people. This also brings future potential for new kinds of both nonprofit and business cooperation.\nVBU Music Registry documents track recordings and all involved participants, from authors to performers. Screenshot of data on the album “Simultaneous kiss” by Foltin.\n<PERSON>: How do you assess the state of Macedonian music industry at the moment?\nVB: The state of the Macedonian music industry can be compared to a person with severe COVID-19 symptoms gasping for air via a ventilator.\nIts predominant business model relies on income generated from live music events. Therefore, the restrictive measures limiting concerts, weddings and other live performances had a severe negative impact on most musicians. This also led to low demand for services of recording studios and producers. The events industry's losses have affected the whole supply chain.\nRoyalties are supposed to provide additional income to copyright holders — composers, songwriters and performers — proportionally to the number of times their recorded music is played in public via media or in hotels, restaurants and cafés. But musicians complain that a small group of well-placed individuals has been abusing this mechanism at the expense of the majority.\nMoreover, actual selling of music on CDs or online has been almost nonexistent, and musicians lack access to other forms of income present in countries with more developed music industries. In my opinion the situation is desperate.\nGV: Has this situation nudged musicians to use the opportunities provided by the internet, such as using digital services to sell their music?\nVB: For most Macedonian musicians, live performances are the primary, and often the only income source. Even before the COVID-19 pandemic some of them had established presences on streaming services and e-music shops. Mostly these are younger performers who have greater affinity for technology.", "363" ], [ "Serbian nationalists want to build an extravagant Triumphal Arch in a Belgrade park · Global Voices\nThe Triumphal Arc in Skopje, North Macedonia, in December 2019. Photo by Global Voices, CC-BY.\nThe nationalist political party Serbian Renewal Movement (SPO), a member of the ruling coalition in Serbia, is pushing for the construction of a massive Triumphal Arch in the center of Belgrade to commemorate military victories achieved in the Balkan Wars and the First World War. The arch would be flanked by statues of King <PERSON> and King <PERSON> of Serbia.\nSerbia's ruling Serbian Progressive Party (SNS), lead by President <PERSON>, has launched other controversial (and costly) urban projects since it came to power in 2012. Those including the Belgrade Waterfront, a musical fountain, a giant flag pole, and a cable-car in the Belgrade Fortress — the latter has been recently put on pause by a court ruling.\nThe SNS enjoys the support of the SPO, a small right-wing party that used to be influential in the 1990s — it even had its own paramilitary wing, the Serbian Guard — but that has since shrunk in size and importance. Writing for Serbian newspaper Danas, political analyst <PERSON> said that the Triumphal Arch proposal was “a way for them to show they still exist.”\nThe SPO proposal, put forward in the Belgrade City Assembly on December 6 without a cost estimate or a funding plan, drew comparisons with similar architectural shenanigans by authoritarian regimes in the Balkans.\nIn neighboring North Macedonia, the “Skopje 2014” project erected over 130 neoclassical structures — among them monuments, statues, government buildings, and museums — in the capital to the cost of at least 763 million USD between 2010 and 2014.", "739" ], [ "The single most expensive structure was a Triumphal Arc called Porta Macedonia, which came to over 7 million dollars. The entire initiative was marred by corruption benefiting cronies of <PERSON> VMRO-DPNME party, who ruled North Macedonia from 2006 to 2017.\nBoth SNS and VMRO-DPNME are members of the conservative European People's Party and have cultivated a strong bilateral cooperation at that time when VMRO was in power in North Macedonia. The two populist regimes have often been implicated in backsliding of democracy and degradation of human rights standards in their respective countries.\nA 2011 cartoon picturing <PERSON>, former Macedonian PM who built a Triumphal Arc in Skopje. Cartoon by <PERSON> AKA Dar-Mar, via Citizens for European Macedonia. Used with permission.\nIn a statement, the SPO argues that Serbia needs such “monumental memorial” in order to “remind us of the glorious moments of our history, inspiring present and future generations to love and defend their homeland.” Party Vice President <PERSON> said:\nПредлажемо да Тријумфална капија буде подигнута у некадашњем Краљевом, данас Пионирском парку између здања Скупштине Србије и Новог двора, односно садашњег Председништва.", "260" ], [ "Old Postcards Reveal Forgotten World War I Memories in Macedonia · Global Voices\nGerman World War I Postcard with a view of Ohrid, Macedonia. Photo from The New York Public Library Digital Collections.\nIn January 2016, the New York Public Library released more than 180,000 digitized items into the public domain. Many of these materials in the library are historical documents that can be referenced in academic studies, as well as downloaded and used or remixed for free since their copyright has expired.\nGlobal Voices already highlighted valuable vintage contents that the library released related to Vietnam, Japan and India. One resource of interest to Europe is the collection of German World War I Photographic Postcards. Made between 1914 and 1918, these photos not only document military aspects of the war, but also provide views of places and people caught within its maelstrom.\nThe writing on the postcard featured above reads:\nThe ancient fortress of Ohrid (Macedonia). A part of the rocky coast of Ohrid Lake. In the background, the Albanian snow mountains.\nIn fact, the Albanian mountains would have been to the back of the photographer and not in the photo. The mountain in the background is Galichica, which today is a national park under threat.\nUpdate Feb. 1, 2016: A photo taken from the same spot almost hundred years later, in January 2016, shows both constancy and change.\nKaneo Beach in Ohrid, Macedonia, January 2016.", "739" ], [ "Photo by <PERSON> (CC-BY).\nIn 2008 Panoramio user <PERSON> posted another recent “version” of this photo, taken from almost the same spot during the Summer. The rocky coast today serves as a beach during the summer months.\nWhile Macedonia was one of the big battlegrounds of World War I (the “Macedonian Front“), the histories and local stories related to this event are not common knowledge for recent generations. To counter this tendency, Open Society Foundation Macedonia published in 2008 a digitized collection of letters by soldiers from Macedonia who had been drafted by the armies of neighboring warring states of Bulgaria, Serbia, Greece. One of the letters from this collection, named “Revealed Testimonies”, reads:\n“We said to ourselves this war has no end. I had to write letters, so everyday I would beg a different person to write my letters. No one could write them as I wanted. I already knew some letters from the Alphabet and I learned how to write, so what's left from the wars was my ability to write letters, although with many mistakes.” – <PERSON>\nGerman troops quartered in the suburbs of Skopje in the houses of local ethnic Albanians. Photo from The New York Public Library Digital Collections.\nIn more recent years, in an effort to promote remembrance and reconciliation the French region of Lower Normandy and Macedonia together organized an exhibition marking the 100-year anniversary of World War I, as well as study visits and an exploration of cultural heritage remaining at the old front lines.\nThe New York Public Library's German postcards offer glimpses of the lives of ordinary people and serve as testimony to the characteristic ethnic diversity which graces Macedonia to this day. They might also give inspiration to researchers of various disciplines exploring the past, from ethnography to historiography.\nEthnic diversity displayed through various attires at the Skopje market during World War I. Photo from The New York Public Library Digital Collections.", "739" ], [ "What changed for the Macedonian people after the country changed its name to Republic of North Macedonia · Global Voices\nThe ceremony of raising the NATO flag in front of the Government of the Republic of North Macedonia on February 12, 2019. In the background: The old name of the institution was removed from the facade a day before. Photo by the Government of the Republic of North Macedonia, public domain.\nOn January 11, 2019, the parliament of North Macedonia approved the constitutional amendments that changed the country's name to Republic of North Macedonia, at last ending a 27-year-old dispute with Greece, which has its own region called Macedonia.\nThe amendment enshrined in national law the UN-brokered Prespa Agreement, signed in June 2018 between Greece's Prime Minister <PERSON> and his Macedonian counterpart <PERSON>. They were both nominated to this year's Nobel Peace Prize for ending one of the oldest active ‘cold’ conflicts in Europe.\nThe change was a crucial step on the Republic of North Macedonia's path towards joining the European Union and NATO, as that had been vetoed beforehand by Greece because of the name issue.\nHowever, that didn't just transform the Balkan country's international relations: it also introduced many changes that affect the everyday lives of its people.\nThe names of government bodies, websites, road signs, and inscriptions on public buildings have either been replaced, or are slated to be replaced, since the new name became official on February 12.\nSymbolically, the road sign on the Greek border was the first to be amended with the new name. Some others will incur in significant costs and are still pending. That includes the plaque on the government's main building.", "739" ], [ "The original sign, with the words “Government of Republic of Macedonia,” was removed on February 11 and a new one hasn't yet arrived.\nFor citizens on both sides of the border, one benefit of improved neighborly relations is the reinstatement of a flight connection between Skopje and Athens after more than ten years. The flight began on November 1, 2018.\nBefore: On February 10, the government seat's building displayed the words “Government of Republic of Macedonia,” in Macedonian Cyrillic. They were removed the next day to be replaced with the new constitutional name of the country. Photo by Global Voices, CC-BY\nChange of personal documents and car stickers\nThe Prespa Agreement stipulates that the personal documents of the citizens of the Republic of North Macedonia will be changed over the next five years.\nDocuments such as passports, ID cards, or car license plates, will be valid over this period, and replacement will be gradual. Citizens whose documents bearing the old name expire before that deadline will get new ones, with the new name, whenever they renew them.\nMeanwhile, the police officers on all border crossings started adding a stamp onto Macedonian passports that says: “This passport is the property of Republic of North Macedonia.” This is a temporary measure while passports with the old name are still valid.\nNorth Macedonia's codes for license plates will also change from MK to NM or NMK, and border authorities have started putting “NMK” stickers on plates over the old MK field.\nOne concession made by the Prespa agreement is the country's code for purposes other than license plates, like the top level internet domain, which will remain MK and MKD, as officially assigned by the International Organization for Standardization (ISO).\nThe inside front cover of a Macedonian passport with a stamp designating the new name of the country in three languages (Macedonian, English, and French). Underneath it, a now-obsolete sheet that Greek authorities used to stamp entry and exit of Macedonian visitors in place of their passports. Photo by Global Voices, CC-BY\nChanges in Greece\nGreece has also introduced a few changes since the agreement's signature, including recognizing North Macedonia's passports.\nUntil February 2019, Macedonian visitors in Greece had to fill in a separate piece of paper in Greek and English which served as a kind of surrogate passport — a document that border police would stamp so that they didn't have to deal with passports bearing the name “Republic of Macedonia.” While on Greek soil, travelers had to keep that piece of paper with them at all times.\nSince the Prespa agreement, Greek authorities have also stopped putting stickers on the cars of Macedonian citizens entering Greece that read, in Greek and English, that the country was “recognized by Greece as FYROM.” The acronym stands for “former Yugoslav Republic of Macedonia,” which was how the UN referred to North Macedonia since the 1990s while a solution to the dispute was pending.\nIn 2012, this was considered a humiliating provocation by Macedonian authorities, as well as by Macedonian tourists visiting Greece who saw it as unnecessary political harassment while they put money into the Greek economy.\nNothing changed for the Greek citizens traveling to North Macedonia.", "363" ], [ "UNESCO World Heritage Site at Risk: Bulgarian Government Allows Construction in Pirin, Citizens Protest · Global Voices\nGrazing chamois in Pirin National Park: a rare and distant view, as these high-mountain animals fear nearby human activity. Photo by <PERSON> (2017), used with permission.\nProtesters took to the streets in 29 international cities, accusing the Bulgarian government of corruption and violation of domestic and EU environmental law after it decided to allow further construction in Pirin National Park, a World Natural Heritage site.\nIn December 2017, the Cabinet passed a plan to allow construction activities in 48% of the park — a move that goes against legislation and is seen as a violation of its status as a protected space. After what many felt was the government's failed response to address the public outcry, environmentalists initiated an international outreach campaign in an effort to pressure authorities to uphold the law protecting the natural heritage site.\nPirin National Park was established to protect biodiversity in Bulgaria’s second highest mountain, an area considered to be one of the most well-preserved natural habitats in Europe. The park spans over 403 square kilometers (around 156 square miles) and contains breathtaking landscapes that range from rocky barren peaks to lush forests and glacier lakes to virgin rivers. It is home to numerous threatened flora and fauna species such as the golden eagle, brown bear and chamois. Locals tell stories that the Balkan lynx (an animal long thought to be extinct in the country) is still roaming in the park's territory.\nA tourist track within Pirin National Park. Old-growth forests in this pristine view are no longer protected from ski resort expansion. Photo by <PERSON> (2017), used with permission.\nDue to its precious natural wonders, Pirin was declared a World Heritage Site by UNESCO in 1983. This status added to its world fame as a tourist destination, a trait valuable to many small and medium-sized businesses in the surrounding area.", "739" ], [ "However, as the adjacent town of Bansko‘s ski resort began hosting winter sports competitions and attracting numerous foreign tourists with its low prices, the sporting complex started to rapidly expand in an unsustainable way.\nSince 2001, the Bansko resort has expanded way over its allowed territory, funneling droves of tourists to the small town. Hotels, ski tracks and their supporting facilities have already encroached into the nearby national park by over 160 hectares, causing soil erosion, biodiversity loss and pollution to sources of drinking water. In 2010, UNESCO excluded the tourist area, spanning 0.6% of the park, from the World Heritage Site to become its buffer zone and continues to express concerns over the ski resort's expansion.\nDue to the popularity of the area, Bansko ski resort has a huge accommodation base for a relatively small number of ski tracks and only a single gondola lift line, resulting in traffic jams and long queues of tourists waiting for their lift ticket. The unsustainable development of the ski resort has lead to a rapid increase and then drop in real estate prices. This financial bubble is growing as prospects of even more expansion become reality. In an effort to keep their prices up and sell more properties around Bansko, Ulen (the company that owns ski infrastructure) has spent years lobbying the Bulgarian government to expand concession areas in the national park and to lift restrictions on construction activities in the protected territory by amending its Management Plan (the ten-year framework of what is allowed within the park).\nBulgarian mainstream media, mostly owned by powerful oligarchs, downplayed the opposition from environmental NGOs by obscuring the issues of greatest concern by publishing stories which focus on issues that favor the resort such as the overloaded gondola lift line. Government officials backed this version by claiming the plan is being amended only to allow a second gondola line, although this is not actually mentioned in the actual legislation. The environmental minister unwittingly called the government's argument into question when he refused a change to the language which would specify that only one lift is allowed to be built, an amendment proposed by renowned altitude climber <PERSON>.\nMainstream media also focused on the economic benefits of development and income for the locals. Residents who members work in the concerned companies and their families expressed public support for the resort expansion, regardless of long-term effects on the environment.\nDespite advice from environmental experts who warned against the development of a large ski area due to climate change and the predicted shortened winter season, the decision makers pressed on. Every year, the ski facility increasingly relies on snow cannons using local water supplies rather than on actual snowfall.\nDespite the fact that new construction would downgrade the park's natural defenses against climate change, on its last session of 2017, the Bulgarian government expanded the territories open to construction from 0.6% to 48% of the park — including the zones set aside for the protection of forest ecosystems.", "112" ] ]

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[ [ "Optimising your code has to be done carefully. Let's also assume you have already debugged the code already. You can save a lot of time if you follow certain priorities, namely:\n1. Use highly optimised (or professionally optimised) libraries where possible. Some examples might include FFTW, OpenBlas, Intel MKL, NAG libraries, etc. Unless you are highly talented (like the developer of GotoBLAS), you probably can't beat the professionals.\n2. Use a profiler (quite a few in the following list have already been named in this thread--Intel Tune, valgrind, gprof, gcov, etc.) to find out what portions of your code take the most time. No point wasting time optimising portions of code that are rarely called.\n3. From the profiler results, look at the portion of your code that took the most time. Determine what the nature of your algorithm is--is it CPU bound or memory bound? Each requires a different set of optimisation techniques.", "242" ], [ "If you are getting a lot of cache misses, memory might be the bottleneck--the CPU is wasting clock cycles waiting for memory to become available. Think about whether the loop fits into the L1/L2/L3 cache of your system. If you have \"if\" statements in your loop, check if the profiler says anything about branch misprediction? What is the branch misprediction penalty of your system? By the way, you can get branch misprediction data from the Intel Optimisation Reference Manuals [1]. Note that the branch misprediction penalty is processor-specific, as you'll see in the Intel manual. The manual will also tell you things like how many clock cycles various instructions take (again, this is processor-specific).\n4. Lastly, address the problems identified by the profiler. A number of techniques have already been discussed here. A number of good, reliable, comprehensive resources on optimization are also available. To name just two, there is the Intel Optimization Reference Manual [1], and the five optimization manuals by <PERSON> [2]. Note that there are some things that you may not need to do, if the compiler does it already--for example, loop unrolling, aligning memory, etc. Read your compiler documentation carefully.\nReferences:\n[1] Intel 64 and IA-32 Architectures Optimization Reference Manual: http://www.intel.sg/content/dam/doc/manual/64-ia-32-architectures-optimization-manual.pdf\n[2] <PERSON>, \"Software Optimisation Resources\": http://www.agner.org/optimize/\n* \"Optimizing software in C++: An optimization guide for Windows, Linux and Mac platforms\"\n* \"Optimizing subroutines in assembly language: An optimization guide for x86 platforms\"\n* \"The microarchitecture of Intel, AMD and VIA CPUs: An optimization guide for assembly programmers and compiler makers\"\n* \"Instruction tables: Lists of instruction latencies, throughputs and micro-operation breakdowns for Intel, AMD and VIA CPUs\"\n* \"Calling conventions for different C++ compilers and operating systems\"", "242" ], [ "While all current CPU's appear to use an iterative approach as aterrel suggests, there has been some work done on non-iterative approaches. Variable Precision Floating Point Division and Square Root talks about a non-iterative implementation of floating point division and square root in an FPGA, using lookup tables and taylor series expansion.\nI suspect that the same techniques may make it possible to get these operations down to a single cycle (throughput, if not latency), but you are likely to need huge lookup tables, and thus infeasibly large areas of silicon real-estate to do it.\nWhy would it not be feasible?\nIn designing CPU's there are many trade-offs to make. Functionality, complexity (number of transistors), speed and power consumption are all interrelated and the decisions made during design can make a huge impact on performance.\nA modern processor probably could have a main floating point unit which dedicates enough transistors on the silicon to perform a floating point division in a single cycle, but it would be unlikely to be an efficient use of those transistors.\nThe floating point multiply made this transition from iterative to non-iterative a decade ago. These days, single cycle multiply and even multiply-accumulate are commonplace, even in mobile processors.\nBefore it became an efficient use of transistor budget, multiply, like division, was often performed by an iterative method.", "129" ], [ "Back then, dedicated DSP processors might dedicate most of their silicon to a single fast multiply accumulate (MAC) unit. A Core2duo CPU has a floating point multiply latency of 3 (the value comes out of the pipeline 3 cycle after it went in), but can have 3 multiplies in flight at once, resulting in a single-cycle throughput, meanwhile it's SSE2 unit can pump out multiple FP multiplies in a single cycle.\nInstead of dedicating huge areas of silicon to a single-cycle divide unit, modern CPU's have multiple units, each of which can perform operations in parallel, but are optimised for their own specific situations. In fact, once you take into account SIMD instructions such as SSE or the CPU integrated graphics of the Sandy Bridge or later CPU's, there may be many such floating-point divide units on your CPU.\nIf generic floating point division were more important to modern CPU's then it might make sense to dedicate enough silicon area to make it single cycle, however most chip makers have obviously decided that they can make better use of that silicon by using those gates for other things. Thus one operation is slower, but overall (for typical usage scenarios) the CPU is faster and/or consumes less power.", "129" ], [ "I think it's best to solve the individual 3 x 3 systems. The problems of doing such a large matrix, containing millions of 3 x 3 systems:\n1. computational cost of assembly: assembling such a large matrix could be take a substantial amount of time (even with a sparse solver).\n2. parallelization overheads: should there be a need to parallelize the code, the large matrix would have to be distributed over many processors and there would be communication overheads for passing information between processors. On the other hand, for individual 3 x 3 systems, the coefficients could easily be distributed over the various processors, after which it would be an \"embarrassingly parallel\" operation (i.e. no communication between processors would be necessary).", "946" ], [ "Furthermore, parallelization using OpenMP or MPI would not be too difficult. On the other hand, for the large matrix, it would probably be easier to make use of a library (such as PETSc: e.g. the example ex2.c is a nice start), rather than to write your own code.\nLastly, I would like to point out that for 3 x 3 systems, it's easy to work out an analytical formula using computer algebra systems (or using Wolfram Alpha). As an illustration, here's how it can be done with the Python package, sympy:\nfrom sympy import *\nx1,x2,x3=symbols('x1 x2 x3')\nb1,b2,b3=symbols('b1 b2 b3')\na11,a12,a13=symbols('a11 a12 a13')\na21,a22,a23=symbols('a21 a22 a23')\na31,a32,a33=symbols('a31 a32 a33')\neq1=Eq(a11*x1+a12*x2+a13*x3,b1)\neq2=Eq(a21*x1+a22*x2+a23*x3,b2)\neq3=Eq(a31*x1+a32*x2+a33*x3,b3)\nx=solve([eq1,eq2,eq3], [x1,x2,x3])\nx.get(x1)\nx.get(x2)\nx.get(x3)\nJust replace x1, x2, x3, b1, b2, b3, etc. with the actual variables in your existing code. If generation of C code is required:\n[(c_name, c_code), (h_name, c_header)] = codegen((\"x1\",x.get(x1)), \"C\", \"test\", header=False, empty=False)\nprint(c_code)\n[(c_name, c_code), (h_name, c_header)] = codegen((\"x2\",x.get(x2)), \"C\", \"test\", header=False, empty=False)\nprint(c_code)\n[(c_name, c_code), (h_name, c_header)] = codegen((\"x3\",x.get(x3)), \"C\", \"test\", header=False, empty=False)\nprint(c_code)\nSample output (for just x1):\n>>> print(c_code)\n#include \"test.h\"\n#include <math.h>\ndouble x1(double a11, double a12, double a13, double a21, double a22, double a23, double a31, double a32, double a33, double b1, double b2, double b3) {\nreturn (a12*a23*b3 - a12*a33*b2 - a13*a22*b3 + a13*a32*b2 + a22*a33*b1 - a23*a32*b1)/(a11*a22*a33 - a11*a23*a32 - a12*a21*a33 + a12*a23*a31 + a13*a21*a32 - a13*a22*a31);\n}\nAnd here it may make sense to pre-calculate the determinant to further reduce the computational cost, i.e.:\ndeterminant = (a11*a22*a33 - a11*a23*a32 - a12*a21*a33 + a12*a23*a31 + a13*a21*a32 - a13*a22*a31);", "904" ], [ "From the comments above, I understand that you want to avoid to copy the vector when you add more cells. The easiest approach is to reserve space for the maximum number of cells that you might want to have:\nstd::vector<YourCellType> myVectorOfCells;\nvectorOfCells.reserve(maxNoCells);\nYour vector has allocated space for creating maxNoCells cells but no cells have been created yet. You can now add maxNoCells to your vector, each operation in O(1) time, without the vector copying itself. However, the C++ Standard requires the push_back operation to be amortized O(1) time. If you add more than maxNoCells, the vector will copy itself, reserving space for k-times as many cells as it previously had (typical implementations choose a k between 1.4 and 2), so that you can keep adding cells to the vector in O(1) time. This resizing operation is not O(1).\nAn AMR strategy begs for a dynamic data structure, like a linked-list of cells that supports insertion/deletion in O(1). A linked-list is, however, much slower than a vector because traversing it requires to randomly jump in memory from cell to cell, generating a lot of cache misses: in modern processors it is faster to swap $n/2$ elements of a vector in order to insert an element than traverse $n/2$ elements of a linked list. So in practice, vectors are the way to go: they are customizable (you can supply them your own allocator), your cells are aligned in memory, you have random acces in O(1) time... as far as you reserve memory first, you can add elements in O(1) time too! As Prof. <PERSON><IP_ADDRESS>vector<YourCellType> myVectorOfCells;\nvectorOfCells.reserve(maxNoCells);\nYour vector has allocated space for creating maxNoCells cells but no cells have been created yet.", "318" ], [ "You can now add maxNoCells to your vector, each operation in O(1) time, without the vector copying itself. However, the C++ Standard requires the push_back operation to be amortized O(1) time. If you add more than maxNoCells, the vector will copy itself, reserving space for k-times as many cells as it previously had (typical implementations choose a k between 1.4 and 2), so that you can keep adding cells to the vector in O(1) time. This resizing operation is not O(1).\nAn AMR strategy begs for a dynamic data structure, like a linked-list of cells that supports insertion/deletion in O(1). A linked-list is, however, much slower than a vector because traversing it requires to randomly jump in memory from cell to cell, generating a lot of cache misses: in modern processors it is faster to swap $n/2$ elements of a vector in order to insert an element than traverse $n/2$ elements of a linked list. So in practice, vectors are the way to go: they are customizable (you can supply them your own allocator), your cells are aligned in memory, you have random acces in O(1) time... as far as you reserve memory first, you can add elements in O(1) time too! As Prof. Bangerth mentioned above, hierarchical data structures like trees also use vectors internally for storing their data.\nHowever, I think it is better practice to allocate memory at the beginning of the simulation. You have to know how many cells you can possibly need in order to check if you have enough memory available. You do not want your simulation in 200.000 processors having to reallocate your data structure or running out of memory and having to swap to disk. In case that happens my opinion is that your program should fail loudly because of an user input error.", "318" ], [ "Use of OS X in HPC and scientific computing is low and it has to do a lot with the pros and cons of OS X w.r.t. the alternative (Linux)\nOS X Pros:\n* Polished UI; still *nix\n* Desktop/Design app(s) such as MS Office, Adobe programs well supported\n* Multimedia very well supported\n* Some people like the Apple ecosystem (iPhone, iTunes etc.)\nOS X Cons:\n* Runs on expensive hardware and not everyone likes Macbooks, specially people used to Thinkpads (keyboard+trackpoint)\n* Cannot upgrade hardware (e.g. if you want to try the latest NVIDIA card with your CUDA app) on desktop/cluster\n* Bloated GUI that cannot be customized (in Linux you can use a minimalist window manager)\n* Package mgmt in Macports/Fink is sub par compared to Linux (Debian) distributions.", "81" ], [ "Most packages are not even actively maintained or are orphaned\n* Some useful tools/programs traditionally did not run or still dont run on OS X. For example ...\n* Sun Studio still doesnt work\n* Valgrind only started working recently and not all features are supported\n* Intel compilers have also been available in recent years\n* Apple doesnt even package a Fortran compiler and you have to rely on 3rd party (mostly individuals) to build binaries that work only on certain OS X versions (which the individual has). Support is rare or non-existant in such cases\n* Commericial scientific apps (ABAQUS, ANSYS, FLUENT and many more in industries such as oil/finance/engg etc.) do not run (natively) on OS X\nLinux (Debian) Pros:\n* First class package management i.e., installation of compilers, most numerical/scientific libraries etc. is a command away\n* Unlike Fink/Macports the packages are much better supported (in Debian you have the option of using bleeding edge/testing/stable versions)\n* Most cluster(s) run some version of Debian/Red Hat so less hassle in porting code(s)\nLinux (Debian) Cons:\n* No standard UI\n* Linux on desktop/laptop(s) may require some tweaking to get everything (suspend/resume, 3D video acceleration, sound etc.) working but this has improved a lot in recent years\nBaring some exceptions most users and cluster/system administrators find OS X easier for desktop productivity and NOT for scientific computing (compiling, using, developing stuff).\nOTOH most Linux users find the latter easier than former and this is reflected int the entire HPC/scientific computing ecosystem.", "81" ], [ "Unfortunately there aren't many textbooks on the topic. I think the best way to learn program analysis today is to survey different courses that are available, play with a few implementations and then look at a few research papers for your specific needs. What follows is a very small sampling of what's out there. Since you specifically mentioned compiler-oriented analyses were easy to find, I will not cover such material below.\nWeb-based resources These are articles that emphasise the use of static analysis outside a compilation context.\n1. A Reverse Engineering Reddit discussion on program analysis has many useful links.\n2. Mozilla Wiki on abstract interpretation.\n3. Deploying Static Analysis, a Dr. <PERSON> article by <PERSON>\n4. A Few Billion Lines of Code Later: Using Static Analysis to Find Bugs in the Real World, <PERSON>, <PERSON>, <PERSON>, <PERSON>, <PERSON>, <PERSON>, <PERSON>, <PERSON>, <PERSON>, <PERSON> in Communications of the ACM.\nUniversity courses on program analysis\n1. <PERSON> at Arhus University teaches a course that covers object-oriented and web technology.\n2. <PERSON> at University of Colorado Boulder has a foundational course that involves an OCaml implementation and a graduate course.\n3. <PERSON> at the University of California Santa Barbara used to have a great set of assignments, but they are no longer available online. Some students who took his course seem to have made a Python implementation available.\n4. <PERSON> has a graduate course on analysis of Android.\n5.", "904" ], [ "<PERSON> at the University of Sarbruecken teaches a graduate course that covers static analysis applications such as timing analysis, cache behaviour prediction, and some shape analysis.\n6. <PERSON> from MSR taught a nice course on statically estimating resource consumption of programs (time/memory) at the Oregon Summer School on Programming Languages.\n7. <PERSON> at the University of California at Berkeley teaches a course that focuses on bug finding and whose topics cover concolic execution and software model checking.\n8. <PERSON> at the University of Maryland teaches a course that covers type systems, model checking, alias analysis and a lot of the other usual material.\n9. <PERSON> spent a year at MIT and taught a comprehensive, foundational course on abstract interpretation. The assignments include an OCaml implementation which go from concrete collecting semantics to some algorithmically non-trivial ideas.\n10. A graduate course on abstract interpretation taught by some leaders in the field is a good place to catch up on even more theory.\n11. <PERSON> taught a short course on abstract interpretation at the Oregon Summer School on Programming Languages in 2009.\nTools to play with\nI am not listing a lot of research tools here. There are many of those but I have tried to list a few that you can download and play with to understand the area better.\n1. Interproc is a very educational tool to play with to learn about numerical static analysis.\n2. The Apron Numeric Abstraction library if you are really into numeric analysis.\n3. Slayer is a shape analysis tool from Microsoft Research.\n4. jStar is an analyzer for Java that is based on separation logic.\n5. Microsoft Research has numerous groups developing numerous tools, many of which are available for download or have web-demos. I cannot list everything here and suggest you play with them.\nThere is a lot more, but that's probably enough to keep you busy for a while.", "897" ], [ "Each stage of the pipeline is only as fast as the slowest stage. The calculation for the latency expresses this by taking the maximum delay (max(D1, D2, D3, D4)) and multiplying it by N, which is the number of stages. Thus: N*max(D1, D2, D3, D4).\nKeep in mind, N is the number of stages, not instructions. The formula measures the latency, not the total run time.\nYour chart demonstrates this, as you can see that there is more and more delay building up in the first and second stages as they finish faster than the next stage.", "7" ], [ "But there is a problem: where does the data from each stage go before it enters the next stage? The simple answer is nowhere: it is stuck in the current stage until the next stage is free. Your third stage is creating a traffic jam!\nConsider this chart, in which each stage has been slowed down to take 4 time units (the n represents that processing is done but the data must wait for the next stage to clear):\n1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28\nS1 n n n S2 S2 n n S3 S3 S3 S3 S4 n n n Done!\nS1 n n n S2 S2 n n S3 S3 S3 S3 S4 n n n Done!\nS1 n n n S2 S2 n n S3 S3 S3 S3 S4 n n n Done!\nS1 n n n S2 S2 n n S3 S3 S3 S3 S4 n n n Done!\nHere we can see that it takes each individual instruction 16 time units to make it through the pipeline (4 stages * max delay of 4). The total run time is only 28 time units. It takes 16 units for the first instruction to run, and 4 more time units for each additional instruction. So the run time formula is something like: N*max(D1, D2, D3, D4) + (IC - 1) * max(D1, D2, D3, D4) where N is the number of stages and IC is the number of instructions.", "242" ], [ "What roadblocks are there to HSA becoming standard, similar to floating point units becoming standard?\nI remember when my dad explained to me for the first time how a certain model of computer he had came with a \"math coprocessor\" which made certain math operations much faster than if they were done on the main CPU without it. That feels a lot like the situation we are in with GPUs today.\nIf I understand correctly, when Intel introduced the x87 architecture they added instructions to x86 that would shunt the floating point operation to the x87 coprocessor if present, or run some software version of the floating operation if it wasn't. Why isn't GPU compute programming like that? As I understand it, GPU compute is explicit, you have to program for it or for the CPU. You decide as a programmer, it isn't up to the compiler and runtime like Float used to be.\nNow that most consumers processors (Ryzen aside) across the board (including smartphone Arm chips and even consoles) are SoCs that include CPUs and GPUs on the same die with shared main memory, what is holding back the industry from adopting some standard form of addressing the GPU compute units built in to their SoCs, much like floating point operation support is now standard in every modern language/compiler?\nIn short, why can't I write something like the code below and expect a standard compiler to decide if it should compile it linearly for a CPU, with SIMD operations like AVX or NEON, or on the GPU if it is available? (Please forgive the terrible example, I'm no expert on what sort of code would normally go on a GPU matter, hence the question. Feel free to edit the example to be more obvious if you have an idea for better syntax.)\nfor (int i = 0; i < size; i += PLATFORM_WIDTH) { // + and = are aware of PLATFORM_WIDTH and adds operand2 to PLATFORM_WIDTH // number of elements of operand_arr starting at index i. // PLATFORM_WIDTH is a number determined by the compiler or maybe // at runtime after determining where the code will run.", "125" ], [ "result_arr[a] = operand_arr[i] + operand2; }\nI am aware of several ways to program for a GPU, including CUDA and OpenCL, that are aimed at working with dedicated GPUs that use memory separate from the CPU's memory. I'm not talking about that. I can imagine a few challenges with doing what I'm describing there due to the disconnected nature of that sort of GPU that require explicit programming. I'm referring solely to the SoCs with an integrated GPU like I described above.\nI also understand that GPU compute is very different than your standard CPU compute (being massively parallel), but floating point calculations are also very different from integer calculations and they were integrated in to the CPU (and GPU...). It just feels natural for certain operations to be pushed to the GPU where possible, like Floats were pushed to the 'Math coprocessor' of yore.\nSo why hasn't it happened? Lack of standardization? Lack of wide industry interest? Or are SoCs with both CPUs and GPUs still too new and is it just a matter of time? (I am aware of the HSA foundation and their efforts. Are they just too new and haven't caught on yet?)\n(To be fair, even SIMD doesn't seem to have reached the level of standard support in languages that Float has, so maybe a better question may be why SIMD in general hasn't reached that level of support yet, GPUs included.)", "82" ] ]

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[ [ "Canning Blueberry Pie Filling\nIntroduction: Canning Blueberry Pie Filling\nWelcome to making Pie Filling! While in this tutorial I'll be showing you how to make Blueberry Pie Filling, this same method is used to make various types of pie filling like Apple, Blackberry, Peach, and more. This is one of the easiest things to prepare for your food storage, plus you can use it for other things like tarts, dump cake, cobblers, and any other recipe that requies a filling like this.\nSupplies\n1. Water bath canner (with lid and wire rack)\n2. Canning jar lids (appropriate size for jars being used)\n3. Canning Jars (I used 8 quart jars - each jar holds one full pie filling. You may want to can this in smaller jars if you like.)\n4. Fresh picked fruit (6 quarts or 24 cups of blueberries in this case.)\n5. Paper towels\n6. 8 - 1 Quart glass canning jars (7 for canning, one for extra filling)\n7. Canning \"tool set\" - including tongs, jar grip, funnel, etc\n8. Measuring cups - for liquids and for powders / sugars\n9. Recipe - link here (Click the word \"here\" to get the Oregon State University pdf file I used.)\n10. Towel\n11.", "69" ], [ "Two pots - one for canning jar lids to strelize in and one stock pot for mixing the pie filling in.\nStep 1: Canning Blueberry Pie Filling - the Video\nThis is the full video of the process below.\nStep 2: Gather Supplies\nIn this process, having everything right on hand pre-measured, makes the process go so much easier. So I have given the items that I have used in this instructable in picture form with the measuring items I have have available to me, yours might be slightly different.\nOnce your supplies have been put all in the same location, start measuring your ingredients. For the Blueberry Pie Filling that I made, that would make 7 Quarts shelf stable Pie Filling, I used the following:\nIngredients:\n*6 Quarts (24 cups) Fresh picked blueberries\n* 6 Cups Granulated Sugar (make sure there are no clumps)\n* 9 1/3 cups cold water (or juice)\n* 2 1/4 Cup Clear Jel (This is NOT clear Jello - it is a refined cornstarch - not found in everyone's local grocery store. You may need to look to a community like the Amish or Menite who have a store near you, or look on Amazon for this product. The product I boiught was Hoosier Hill Farm Clear Jel, 1.5 Lbs.) ** This is an affiliate link, while you will not be obligated to buy, if you do click and/or purchase, I do get some credit from this link.)\n* 1/2 Cup Lemon Juice\n** You can also include Food Coloring if you want but I did not use it. The link to the full recipe, and other pie fillings is here.\nFull Pie Filling Recipe link.\nStep 3: My Outdoor Kitchen\nI've set up a \"cooking station\" outside to help keep heat from loitering in my house. So, I'm using a double burner propane stove to have my water bath canner on one burner while I use the other burner for both cooking the pie filling and sterilizing the two part lids for the jars.You will see in several pictures that I also have a table with the rest of my tools on it. I got a folding table at Wal-Mart for about $40, but you can also get a 4x8 folding table from Costco for about $50, both are good, I just lucked out with the one at Wal-Mart.\nStep 4: Pick Then Rinse the Blueberries.\nI went to a local farm called Blueberry Meadows and picked a total of 18 pounds of blueberries between two pickings. The second picking of 10 pounds of berries is what I used here. After picking through the berries dry, I rinsed them in water to get the stuff that I couldn't pick out dry. The last two images are the things that I tossed out - the stems, leaves and rotten berries.\nStep 5: Boiling Water and Start the Pie Filling\nStart one burner with the canner boiling water with jars upside down to keep sanitary. Then in the second pot, combine the sugar and Clear Jel and mix throughly. Remember that when measuring dry ingredients, not to just scoop the product out in the measuring cup - you need to level the measuring cup as indicated in the last picture, so you don't get too much in this case of the Clear Jel.", "491" ], [ "Our Family - Crab Seafood Boil\nIntroduction: Our Family - Crab Seafood Boil\nDo you have an upcoming \"Family & Friend\" gathering and you want to try something NEW? Then add a little FUN and GOOD Eating with this recipe \"Our Family - Crab Seafood Boil\".\nWith this recipe everyone gets to be a part of the fun. Our Crab Seafood Boils have been successful with groups up to 25 family members. Everyone brings something to throw in the pot!\nIt's been one of our all time favorite Family Gathering meals for over 10 years.\nGive it a try!\nBe CREATIVE and PERSONALIZE your Family Crab Boil & share it with us!\n* I am including how to adjust the amounts of ingredients to fit the size of your group. *\nSupplies\nIngredients for + 16 Adult Family Members\n* 10 lbs = crab legs - frozen\n* 4 lbs = large shrimp - frozen prefer peeled\n* 4 packages 12 -16 oz. = kielbasa / sauage\n* 8 lbs = potatoes\n* 2 - 8 piece pkg = corn on the cob - frozen\n* 5 lbs = carrots\n* 5 medium = onions\n* 2 bunches/bulbs = garlic\n* 2 - 3oz bag/pouch = \"Crab Boil in Bag\" Zatarian\n* 2 sticks = butter (1 to add to the pot & 1 for the table to butter the corn)\n* 4 gallons = water (optional - in place of one gallon of water you can use 12 cans -12oz beer)\nEquipment\n* burner\n* propane tank\n* lighter\n* large pot / (keg)\n* tongs - extra long\n* spoon - extra long\n* sharp cutting knives\n* cutting board\n* timer/watch\n* mitts or hot pads (2 minimum)\n* paper towels\n* plastic table cloth/shower curtain\n* newspaper /cardboard box\n* large table (area) for dumping crab boil with cooked\nStep 1: To Adjust the Ingredients to Fit Your Size Group\n1/2 - 1lb @ adult = crab legs - frozen\n1/4 lb @ adult = large shrimp peeled - frozen\n1 pkg @ 4 adults = kielbasa / sausage packages 12 -16 oz.\n1 lb medium potatoes @ 3 adult = potatoes - (3 med potatoes @ lb)\n1 small cob @ adult = corn on the cob - frozen (you can use fresh cobs)\n1 lb @3 adults = carrots\n1 medium @ gallon of water = onions\n1 bunch/bulb @ 2 gallons of water = garlic\n1 - 3 oz bag/pouch @ 2 gallons of water = \"Crab Boil in Bag\" Zatarian ( adjust to your taste)\n1 stick @ pot = butter\n+/- 1 gallons @ 4 adults= water (Make sure you can cover your ingredients)\n(optional - in place of one gallon of water you can use 12 cans -12oz beer)\nThese are estimates that we have used over the years. Remember to use your own judgement based on the appetites of your guest.", "265" ], [ "We are a hearty eating crew and we always have plenty to go around! These are photos from additional boils.\nStep 2: Start the Burner\n- Use a pot that is large enough to fill the pot 2/3 with water. There needs to be room to add the ingredients.\n* Add the \"Crab in Bag\" Pouches.\n* Bring to a boil BEFORE Adding the vegetables.\n- When using 4 gallons of water/beer mixture it takes approximately 40-45 minutes to bring to a boil. So we start the water heating up while we prep the ingredients. Once the water has started to boil then you will be adding the ingredients.\n- Tip - Secure your area for safety. With many toddlers, we choose to place a boundary around the pot with wooden stakes and a yellow rope.\n- As you see in the photos we use a keg for our boils. We have also used the pot many use to deep fry turkeys in.\nStep 3: Prepare & Cut Up Food\nKielbasa / Sausage = Cut into 2\" pieces.\nPotatoes = Cut into quarters.\nCarrots = Cut into 2\" pieces.\nOnion = Cut in half.\nGarlic = Separate the cloves, trim & peel and then cut cloves in half.\n**Keep Seafood & Meats on ice until ready to add to the boil.\nStep 4: Water Is Boiling So Time to Add Vegetables\nAdd the Potatoes, Onions, Garlic -\nCook for 20 minutes\n*Check that the potatoes are STARTING to get tender. If not, then add additional time now - NOT later.", "901" ], [ "Italian Grilled Cheese Sandwich\nIntroduction: Italian Grilled Cheese Sandwich\nThis is my simple take on an Italian Grilled Cheese Sandwich. What makes it Italian you ask? I use garlic butter on the bread and mozzarella cheese.\nSupplies\nBread\nButter\nGarlic\nMozerella Cheese\nMarinera Sauce\nOregeno\nKnife\nGarlic Press\nCutting Board\nStove top\nGriddle or Pan\nStep 1:\nI use French Bread from the local grocery store's Bakery. It's baked fresh daily and taste delicious. I cut two 3/4 inch slices of bread. It can be a thicker or thinner slice it doesn't really matter it will still be good.\nI make some garlic butter using 2 cloves of garlic that I squeeze through my garlic press in to a small bowl. I then add 2 tablespoons of room temperature salted butter to the minced garlic and stir it together.\n*I prefer salted butter but unsalted will also work.\nStep 2:\nThis, in my opinion is the main take away from this Instructable. Butter all 4 sides of the bread I recommend this for regular grilled cheese as well it just adds a really nice crispy-ness to the bread.\nStep 3:\nI don't measure the cheese I just put aside what I think will fit in between the bread. You can always add more when it comes time to grill it. I also like to use a bit of marinara sauce (about 2 tablespoons) to add a little bit of tomato-ey tang to the sandwich. The sauce in the pic is just leftover from our pasta night.\nStep 4:\nIn our house we have a dedicated pan for tortillas and grilled cheese, that's all that we make on that pan. I heat the pan to a medium low heat and place both slices down on the pan. You don't want it too hot because you will be leaving the bread on the pan for a while to make sure the cheese gets nice and melted.", "808" ], [ "So its better to error on the lower temperature side than the higher.\nStep 5:\nI listen to the butter sizzling when it stops sizzling then I check the bread to make sure it is nice and toasted. We are only toasting one side at this time this will be the inside of the sandwich. Once the bread is nice and golden brown remove them from the pan and place on a plate. Next add a smear of marinara sauce to both pieces of bread then add the cheese to one piece only. This is optional but I like to add a dash of dried Oregano to the cheese, I really love the mozzarella and Oregano combination so add it but you can leave it out.\nStep 6:\nNext place the loaded bread slice back on the pan and top with the other slice. Let it grill for a little while and then use a spatula to press down on the bread. You don't want to make it completely flat you just want it to compress the bread and get even browning. The pressing also results in a nice crispy crust on the bread which gives you a really nice bite. Once the first side is nice and golden brown flip the sandwich and press the other side as well. Once both sides are cooked to your satisfaction remove from the pan and let it cool for a minute or two, the cheese will be very hot so your patience will be rewarded.\nStep 7:\nOnce its cooled, enjoy it just like that or slice it and revel in the gooey-aucity of the mozerella cheese-ness. This is one of those sandwiches that can make a bad day just fade away. I hope you all will try making this sandwich I don't think you will be disappointed.", "692" ], [ "Tabletop Sand Grill\nIntroduction: Tabletop Sand Grill\nHaving a small open tabletop grill can be a great centerpiece for any outdoor setting. When looking at the sand it almost takes you back to camping on the beach with a small campfire. I think guests are even more surprised to see it work. I was inspired to make this after visiting a Korean BBQ chain for the first time. It's really cool how you and your friends can all grill on a small tabletop grill rather than having to use a full sized one that only one person gets to operate. I infused this idea of Korean BBQ and a Edo Style Hibachi grill to create a extremely stylish and easy to make tabletop grill that is guaranteed to wow your guests when they come over.\nSupplies\nHere is what you will need to create a successful Tabletop Sand Grill\n* All-purpose Sand\n* A terracotta pot or terracotta saucer\n* Charcoal (preferably Lump charcoal)\n* 4 Terracotta Pot Feet (Will need more to lift your grill off the table if it is shallow like mine)\nOptional Items\n* Extra Terracotta Pot Feet to lift your Grill off of the table (I used custom made concrete feet)\n* A grill grate\nStep 1: Pour Sand Into Your Desired Container and Smooth It Out\nOnce you have your desired Terracotta Pot, (I used a 16 inch Clay Saucer, and a 6 inch Standard Clay Pot), pour your sand in pot. Make sure that the sand is at least a half an inch from the top of your container. This is to prevent potentially hot sand from spilling over the pot.\nOnce you have poured your sand in your desired pot, its time to smooth it out and make any design in the sand that you want. I used my fingertips to create wavy divots in the sand. This is just purely for aesthetic.\nDo this for all of the containers that you will be using. If your pot have a draining hole in the bottom of it make sure that you plug it up somehow. For my 6 inch Standard Clay pot I just used a piece of aluminum foil to cover up the draining hole.\nOnce you have all of your pots filled place them in their respective spots.", "34" ], [ "For example I placed my 6 inch pot towards the edge of 16 inch clay saucer.\n**Note: If you are using Pot Feet to elevate your grill off of the table make sure that you put them on before placing the sand in your pot.**\nStep 2: Place Your Grilling Supports\nAt this point you can use some of those Terracotta Pot feet to use as grilling supports. I placed two of them besides each other so that I could have more grilling space. I used four in total. When placing the terracotta Pot Feet in the sand make sure that they are deep enough in the sand that they don't fall over at the slightest touch.\nFor this part you don't have to use Pot Feet you could shape a piece of metal if you have the tools to do so. Just make sure that the metal will be food grade safe. There are also lots of other options that you could explore too, get creative!\nStep 3: Light and Place Your Charcoal\nLike any other grill you need some type of heat source. Light your charcoals like you would any other grill. I would suggest not using lighter fluid though and instead opt to use a charcoal chimney with some crumpled up newspaper or wax Firestarter.\nI used Pok Pok Thaan Thai Style Charcoal Logs which burn for a long time.\nStep 4: Start Grilling\nThe final step is to find something to throw on the grill. I used some thin cut Sirloin pieces that were marinated in teriyaki sauce.\nRemember that it doesn't just have to be a grill. Charcoal is just like any other heat source and can heat up other things too. For example I placed my teapot on the upper portion of the grill. After a while I even added a grill grate so that I could put one of my mini cast iron pans on there.\nGet Creative!", "34" ], [ "Natira (Leftover) Fried Rice\nIntroduction: Natira (Leftover) Fried Rice\nHere is an easy meal to make in 30 mins or less. The components are Rice, Meat and Veggies.\nRice – The best rice for fried rice is day old rice. Cold rice will work if it was made in the morning, but it must be cold.\nMeat – You can use chicken, pork or steak, but chicken and pork taste the best.\nVeggies – Veggies are what you have in the fridge. I use what is cooked but raw celery and frozen onions are a tasty addition.\nThe Story:\nMany a night I have come home after work to be staring at an empty stove with 5 or 6 hungry people longingly looking at me. Immediately I would go to the fridge and pull out any leftovers, from those humble beginnings this meal started. During the pandemic this Natira Fried Rice is a weekly staple. It has become a comfort meal.\nThere is no MSG, no added Salt, just the explosion of flavor from each ingredient culminating prior to the empty bowl. Leaving the satisfaction of heightened senses and a full stomach.\nThis is a Healthy and Tasty meal. While cooking each ingredient a tantalizing aroma will be produced, which is the beginning of making a great meal. Each smell wafts through the air calling familiar memories. As new scents are added the complexity and anticipation builds.\nThe benefits of this meal are:\n1) Easy to make,\n2) Using precooked foods reduces time.\n3) A good use of small portions from former meals.\nStep 1: Ingredients\nThis meal will serve 4 people, increase amounts when feeding more guests.\nSkill Level:\nEasy\nTime to Complete:\n30 minutes +-\nTools:\nLarge Fry Pan,\nLarge Metal Spatula,\nVegetable Knife,\nCutting Surface and\nTeaspoon.\nIngredients:\nRice - 3+/- cups cooked,\nMeat - 3-5 pieces,\nVeggies - 1/2 cup,\nChopped Onions - 1/3 cup,\nMinced Garlic - 2-4 teaspoons,\nCelery - 1 stock,\nPine Nuts - 1/3 cup,\nToasted Sesame Oil - 1/4 cup and\nWater as needed (not shown).\nNot everyone has Minced Garlic, Pine Nuts or Sesame Oil. Substitute with what you have. I will add substitutions as needed.\nLet’s go make a Natira Fried Rice.\nStep 2: Veggies\nPrepare any uncooked veggies.\nIf you are using uncooked or frozen veggies, this is the time they can be \"steamed\" while you are cutting and searing the meat. In this step you will be \"cooking\" those veggies that need more time to heat. Some vegetables do not require much time to cook.", "277" ], [ "Onions are often overcooked and loose their flavor because they are added too soon into the cooking process. For this meal I didn't have any leftover veggies so I cut up and \"steamed\" some peppers.\n1) Cut the veggies into small pieces.\n2) Place into dish with small amount of water in microwave.\n3) Heat for 1 - 2 min depending on amount and type of veggies.\nNext step Meat\nStep 3: Meat\nHere you are searing the meat. The burner is set at Medium / High heat. After you cut your meat into cubed pieces sear the pieces for a couple of mins until the aroma permeates the kitchen. When meat is heated move the meat from the center of the pan to the edges. The meat has already been cooked and has the previous meal's flavor. No need to add more spices.\n1) Cut meat into cubes.\n2) Set to Medium / High heat.\n3) Sear meat 3 mins.\n4) Move meat to pan edges.\nNext step Vegetables\nStep 4: Vegtables\nIn this step you are adding the veggies to the seared meat. Most veggies need more time to heat add the cooked or \"steamed veggies\". Cook for a couple of mins until the aroma permeates the kitchen. When veggies are heated move the veggies from the center of the pan to the edges. Keep the heat on Medium / High. This is not the time to add the onions, onions do not require as much cooking time.\n1) Add 1/2 cup of veggies.\n2) Keep Medium / High heat.\n3) Heat veggies for 2 mins.\n4) Move veggies to pan edges.\nNext step Pine Nuts\nStep 5: Pine Nuts\nPine nuts have a nice aroma and flavor when cooked. Cook for a couple of mins until the aroma permeates the kitchen. When nuts are heated move the nuts from the center of the pan to the edges. Keep the heat on Medium / High.", "280" ], [ "Easy Challah Bread Recipe\nIntroduction: Easy Challah Bread Recipe\nMy family and I love bread and this bread is my favorite! It is an Easy, Simple, and DELICIOUS Challah Bread recipe. It is often gone in a day, costs about $7 and presents beautifully. The bread itself is very soft and goes great with butter and jam or even with ham and cheese. This Challah Bread is great for large groups because there is plenty to go around.\nStep 1: Gathering the Supplies\nIngredients:\n1 Tablespoon of Active Dry Yeast\n4 Cups of Flour\n7 Large Egg Yokes\n1 Large Beaten Egg\n1/4 Cup of Sugar\n2 Teaspoons of Kosher Salt\n6 Tablespoons of Olive Oil\n1 Tablespoons of Everything Seasoning (Sesame Seeds, Poppy Seeds, Granulated Garlic, Granulated Onion, and Salt)\n1 Cup of Warm Water\nStep 2: Mixing\nMix the Yeast and 1 Cup of Warm water into a small bowl and let it sit for 5 minutes.\nStep 3: Mixing Pt. 2\nUsing the bowl of a mixer; combine the bread flour, egg yolks, sugar, salt, and oil. Add the yeast mixture into the bowl. Kneed them together with a hook attachment at medium speed until the dough comes together and pulls away from the sides of the bowl, around 2 minutes. Scrape the dough off the sides if needed.\nStep 4: Resting\nCover the bowl with a towel until it has doubled in volume, 1-2 hours. Depending on the temperature of the kitchen it will be faster or slower.", "887" ], [ "(warmer = faster, cooler = slower)\nStep 5: Braiding\nPunch the dough down (literally punch it) and divided it into 3 pieces. On a floured surface, roll each piece into a rope around 20 inches in length. Braid them together to form a loaf.\nStep 6: Cooking\nPlace the bread on parchment or silicone mat lined baking sheet and cover it with a towel. Let it rise until it has doubled its' volume again which is about 30 minutes. Meanwhile preheat the oven to 350˚F. Brush the loaf with the beaten egg and sprinkle the everything seasoning. Bake the bread until golden brown, 20 to 25 minutes.\nStep 7: Eating\nLet it cool for a few minutes after baking before devouring it.\n*Highly recommend* Cut into the loaf and spread lots of butter on it. Eat it with pleasure.\nStore in a Plastic bag or wrap in cellophane if you don't each it in one sitting. ;)", "195" ], [ "Victorian Chocolate Eggs; a Different Take on a Sugar Egg\nIntroduction: Victorian Chocolate Eggs; a Different Take on a Sugar Egg\nAbout a month ago I stumbled upon this post \"My Grandma's Victorian Sugar Eggs and Royal Icing Decorations\" by <PERSON>. I thought they were so cute! I had never seen any before and I loved them.\nHowever, there was one thing that I didn't love about them. She has a tutorial on her blog there where she tells you how to make them, but when I read the ingredients I thought, \"That doesn't sound very yummy. I don't think I would want to eat that.\"\nVery cute, but practically inedible. Not my kind of thing. I think that food can be pretty or beautiful, but it should still be something you would actually want to eat. So I decided to try my own take on the sugar eggs and make them with chocolate instead.\nSupplies\n1. Latex water balloons, washed (just run them under the sink and dry them off on a towel)\n2. Balloon pump\n3. Milk chocolate chips\n4. Small bowl for mixing\n5. Spoon for mixing\n6. Scissors or a sewing pin\n7. Small knife\n8. Parchment paper\n9. Masking tape (optional, not pictured)\n10. Royal Icing*\n11. Piping tips (use whichever ones you want - I am using a small star tip and a small writing tip\n12. Piping bag with coupler OR you can use the old ziplock bag method\n13. Scribe tool. Not necessary, but nice for adjusting stray icing.\n14. Food coloring (optional; depends on design)\n15.", "305" ], [ "Small bowls for mixing\n16. Spoons for mixing\n17. Sprinkles, optional.\n* I am using <PERSON> royal icing recipe, which can be found here. I am not going to walk you through how to make royal icing because there are a bajillion tutorials out there on the internet or in books.\nStep 1: Royal Icing Transfers\nSo now we are gonna make royal icing transfers. These are actually really addicting to make and really fun.\nI spread out a length of parchment paper. How much you want depends on how many transfers you will be making; and I will be making a ton of them. I can't leave my transfers just sitting where I am working, so I have put my parchment paper inside a flat baking pan so I can move them without disturbing the icing.\nNext, I drew some little pictures of snowmen and Christmas trees. These will be my \"stencils\" that I will draw my icing over top of. I slide the sheet under the parchment paper. You can see the designs through the parchment paper so that you can draw with the icing using your original drawings as a guide. You can also freehand if you want to or draw your own designs, but if you don't, I have included a sheet you can printout with a few designs I made that you can use freely.\nI added masking tape to the corners to try to keep the sheet from sliding, but it didn't really end up being that necessary.\nWith the food coloring, I mix a bit of green icing for the Christmas trees. I am also going to use green icing for the snowmen hats, scarves, and faces.\nTIP: I am using a piping bag, but you could use a ziplock bag. Cut a small bit of one of the corners off, insert the piping tip and push it out of the bag about halfway. Take some masking tape and tape around where the cut edge of the bag meets the piping tip. This will reinforce the bag. Still be careful with it and keep an eye on it while you pipe because ziplock bags are notorious for splitting.\nWith the writing tip or a small round tip, simply trace the design onto the parchment paper with the icing. You can use the scribe tool to swirl the icing around and fill the design. Don't make your icing layer too thin - it will crack. Your royal icing should be around flood consistency, that is it will not hold peaks and will smooth itself out when piped.\nAfter I pipe the snowman's body, I switch to green to pipe the hat, scarf, and face. That snowmen looks a little evil, but the next ones were better.\nI do the same for the Christmas trees, but I added flat, round sprinkles on mine to be lights. You can skip that, or you could add edible glitter, or coarse sugar, whatever you want.\nLeave the transfers to dry for at least one day. When they are dry, they should easily pop off with the help of the scribe tool or a toothpick. Just get under the edge and carefully push/pop it up and it should come off easily.", "744" ], [ "How to Make Apple Cider on a Budget With Everyday Items\nIntroduction: How to Make Apple Cider on a Budget With Everyday Items\nOn a walk a few years ago, I found two apple trees on an abandoned property that were completely laden with apples; but, there was no one there to enjoy them (beside the insects and animals I guess)! There were so many apples, some of which were on the far side of ripe, that there was no way for me to eat or give away the apples fast enough. This prompted me to look into how to make apple cider, in order to preserve my unexpected bounty. After a quick search, I found that the tools required were fairly \"rudimentary\" in their action, but still way too expensive to justify maybe only one year of use. I looked around the house to find materials for a workaround, and this was my solution\nSupplies\n* 3 - 5 gallon buckets: https://amzn.to/2Qkxeup ... You can get buckets way cheaper at Lowes/Home Depot/Menards, but these are food grade if you're interested\n* 1- 5 gallon bucket lid: https://amzn.to/2EcTCn6 ... cheaper at hardware stores\n* Bottle Jack: https://amzn.to/3l9EWpo ... I purchased mine from Harbor Freight with a coupon for about $6 less than this one, but this should work.\n* Mesh laundry bag: https://amzn.to/3laQd9k\n* 2x4 cheapest you can find that's not warped: You'll use this to make your box frame ~17 inches x 20 inches (interior dimensions)\n* Scrap wood piece(s): that is roughly the size of the diameter of your bucket. You will place the bottle jack on top of this, and the bigger the piece of wood, the more surface area their will be pushing down to make the cider.\n* Paint Roller Tray (preferably aluminum): https://amzn.to/3hhA7rS ... you can get these way cheaper at a local hardware stores\n* Paint Stirrer: https://amzn.to/2FBTH47 ... you can find these way cheaper at a local hardware stores\n* Hammer Drill: https://amzn.to/2FGdXS9 ... wait for a coupon and get it from Harbor Freight, or just use a regular drill if you have one.\nStep 1: Prepping the Press Drainage Bucket\nIn ONE of your three buckets, drill ~3/8\" holes around the circumference of the bucket, about 1/2\" from the bottom. Make sure the drill bit does not puncture the bottom of the actual bucket, however.\nStep 2: Prep the Grinding Bucket\nIn the bucket lid, drill a ~1\" hole to accommodate the paint stirrer shaft. Run the paint stirrer through the hole and into your drill chuck.", "496" ], [ "Fill up a bucket (one with no holes at the bottom) about a half to 3/4 full of apples. Press the lid/drill combo into place at the top of the bucket and start grinding! You should chop/mash the apples up as best as you can to increase the cider yield. Just a heads up, this is the most time consuming part of the process so be patient in order to get smaller chunks of apple, and ultimately more cider. Or even better, come up with your own budget mashing solution that doesn't take as long. This is just what I had on hand. (The mash should be roughly the consistency of EXTRA chunky apple sauce)\nStep 3: Prepping the Press Frame\nBuild the press frame out of 2x4's. The interior dimensions should be ~17\"x20\" or big enough for your bucket to fit inside stood up. I advise putting at least 3 screws at each joint. You will be putting a lot of force against this frame shortly.\nStep 4: Prepping the Press Drainage Tray\nDrill 3-4 holes in the deepest well portion of the paint rolling tray. This is where the cider will ultimately seep into the catch bucket below.\nStep 5: Put the Mash Into the Press Bucket/bag\nTake your clean laundry bag and drape it into your drainage bucket with the holes at the bottom, like you're putting a trash bag into a trash can. Pour the mash apple mix into the bag in the bucket. The weight of apples themselves will already start producing a bit of cider, so make sure you have the bucket placed on your drainage tray, or in another bucket temporarily during the pour. Cinch up the laundry bag and place a piece of scrap wood on top of the bag and mash.\nStep 6: Start Pressing!\nAlright, this step is admittedly going to take a bit of coordination, or perhaps a partner.", "496" ] ]

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[ [ "An absolutely brilliant design from 1981 has been re-birthed in Modern trappings to astound, fluster, and magnify a new generation of gamer. The core game play found in this elegant box is pure and simple yet packs hours of entertainment as you and a group of friends take a puff from the pipe, pass the brandy, and pull on your ditto suits.\nOne must understand before diving into Sherlock Holmes Consulting Detective, that this is not Clue or even the excellent Mystery of the Abbey – this is a wholly unique experience you cannot find elsewhere. There’s no die rolling, no cards, and not even a board. Instead, you get a simple yet effective paper map of London, a short rules booklet, a small London Directory, and 10 case books and their accompanying London Times for the day.\nOne of the many beautiful elements of this game are that the rules can be summarized in less time than it takes to setup Hey, That’s My Fish! First you open the booklet for the case you wish to play and read the introduction aloud to the group. This will be a couple pages of flavor text (<PERSON> insulting <PERSON> or remarking on his own genius) which will result in a number of clues. Clues are not spelled out for the group but rather must be picked out and analyzed at the table’s discretion. You will typically have a couple names you wish to investigate further, maybe a location or two, and possibly one or more peculiar details.\nWhile peculiar details, such as the victim’s waistcoat bearing odd soot or a long lock of the cadaver’s hair missing, should be noted and logged, the majority of information consisting of people and places will require you to follow-up and dig deeper. What this means in standard practice is shouting at <PERSON> across the table to get off his phone and look up “Sir <PERSON>” in the London Directory. The Directory is a smaller book which lists names and places of business that you can visit. Next to the name will be a location which corresponds to the map (“37 SW”). You then take the Case Book and look underneath the section corresponding to the location to see if there is any information at that location. If so, there will be a paragraph or two and possibly a picture which will offer additional information and more places to go to.\nThis will continue as you discover additional seedy people you had no idea existed, uncover affairs fit for the best Soap Operas, and slowly formulate in your head who you think killed the victim and what their motives were.", "581" ], [ "The game ends a bit abruptly as you must decide when you wish to stop pursuing leads and flip to the back of the Case Book where a set of questions exist. There are two sets of questions, the first dealing specifically with the murder and the second set pertaining to extraneous details you may have uncovered (and which may have nothing to do with the murder).\nSo, besides following an interesting story and having a huge light bulb appear over your head, what’s the point? The rub is that you are competing with <PERSON> to solve the case and must do so in a quick and efficient manner. You gain points by answering questions correctly while losing them for following extra leads beyond what <PERSON> used. This adds a necessary element of tension as you grapple with 3 leads and agonize over which ones to prioritize but it also can add a large element of frustration. See, <PERSON> is a cheating whore that makes deductions only <PERSON> could justify. While it is possible to beat <PERSON>, the majority of the time you will lose horribly and this is something you will just have to deal with to enjoy the game. In the end, this minor flaw does not spoil a fantastic, riveting experience.\nWhile I’ve touched on the beauty of the pure distilled deduction this game offers without any extra chrome or fat, I have yet to really mention the single best element of this game – the glorious London Times. I noted that each case also has a partner issue of the London Times but I haven’t hammered home the pure awesomeness of this single sheet of thin paper that is printed double-sided. The newspaper is chock-full of delicious 19th century articles, obituaries, columns, and even company adds. Sometimes the format will be jarring and will make no sense and you can’t help but arch an eyebrow and show it to the group. Other times you will come across odd snippets of information clearly hiding something and intended for an audience other than yourself.\nThe idea is that hidden on this single page may be one or more clues pertaining to the case. We have a go-to London Times person in our group and she spends probably 70% of the game reading and re-reading the damn thing – and she loves every second of it.", "504" ], [ "Plastic tubs come with warning labels making sure you don’t place a baby inside and seal it. I had a hot water heater that had several warning images which read like a hilarious comic strip with the protagonist ending in fiery death. Likewise, the Emperors of Eternal Evil did their due diligence with the following caution:\n“Psycho Raiders is a very visceral experience and we have rated it X. Anyone under the age of 18 is NOT permitted to play. Pregnant or players with a fragile or nervous disposition are strongly encouraged NOT TO PLAY THIS GAME!”\nI’m afflicted with hyper-tension and have an innocuous heart murmur but I live life on the edge and toughed this one out for you guys; thank god I wasn’t pregnant.\nKill! Kill! Kill!\nSo up front, this thing is as crazy as that tongue in cheek warning label. It’s a hex and counter wargame simulation of a slasher horror flick and it’s physically packaged in a magazine format that screams low-fi and underground. It’s reminiscent of an early 90’s Metal Zine and it feels like you’ve come across something your parents have forbidden and you shouldn’t own. It has that special unique feeling like you’ve just discovered a band no one’s heard of and that sense of ownership and rebellion that’s deeply associated.\nThe magazine is chocked full of obscene, evocative, and hilarious artwork. There’s little comic strips that make you chuckle, large drawings featuring gore and nudity, and a constant sense of the perverse that has you wondering what’s going through these guys minds? That’s ultimately why we love this team as their designs come from so far out of left field that it can’t help but be a home run. The whole thing just reeks of care and passion that it rips through your chest and pulls viciously on all of your heartstrings.\nComponents here are even cruder than its predecessor Cave Evil. You get one counter sheet with plain but effective artwork, a paper map which is pretty solid and evocative, and several sheets of cards that you must cut out. You need to supply your own 6-siders and will need to photocopy small character sheets. The rules make up the bulk of the magazine, interspersed with a couple of drawings and a nice centerfold with a scantily clad woman in a gas mask. The rules themselves are simple and easy enough to grasp so you will be able to get playing this one pretty quickly.", "504" ], [ "There’s also a generous amount of optional rules found near the back that add some depth and additional bite.\nIf Psycho Raiders was released as a traditional game without the phenomenal package it would likely be uninspiring and a bit sub-par. The game is purposely unbalanced and seeks to simulate the horrific events that occurred in its 1978 story featuring a group of campers fleeing the Psycho Raiders. If the campers are caught early they will be cut down mercilessly by the hunters as death comes swift and without prejudice. Players can get eliminated right away and the game does not coddle you, grinding your broken skull into the mud as a reward for committing mistake or tactical error. However, it needs this overarching sense of punishment and execution to deliver upon its promise of intensity and terror – which it succeeds at admirably.\nAs the wall of fire cuts <PERSON> off, he finds himself surrounded and ready to fight like a cornered rat.\nThe tension and horrific nature of the game is the main selling point. This constant sense of danger and being up against the odds makes playing the campers a tense and harrowing experience. Your main weapon is hiding which features a neat and simple mechanic of allowing you to place down duplicate counters of your character and you write down the number corresponding to your actual position. From the perspective of playing a Psycho Raider you feel like this terrible god, hunting these filthy animals down so that you can hack them apart and feast on their remains.\nIn addition to the atmosphere the game is just packed with small clever touches. This is the same quality that endeared me to Cave Evil and it’s what these guys do exceptionally well. You have stuff like a blow torch which is relatively weak unless your target is being grappled by another player. The damage system is stellar in that each point of damage causes you to drop a stat by 1. The tough choice between reducing your fighting Strength or your Speed is painful. If a blow would reduce your stats to 0, you draw a KILL card. If the type of weapon used against you is present on the card (Fist, Melee, Gun, or Fire), you die instantly. The cards have a great illustration of a particularly gruesome death and work to elevate the experience in their own right.", "558" ], [ "That woman at the back of the room that you haven’t been able to take your eyes off of. The gorgeous and mysterious honey whose lit a fire in your guts and has you questioning everything you once thought was true. She’s not only a total knockout but she’s unequivocally brilliant, focused, and intellectually challenging. She’s perfection personified through overwrought genius. She’s Earth Reborn.\nIn 2010 <PERSON> bestowed a gift of epic proportions. This large box of finely sculpted plastic and multi-layered mounds of cardboard is not dripping in theme – it’s overflowing in bucket loads. This is a deep, overly thematic post-apocalyptic miniature game with enough sub-systems and multi-faceted rules to satisfy the most gluttonous of masochists. You can search rooms, torture prisoners, launch missiles from a silo, and put your buzz-saw fist through a mech’s face.\nLearning this game is a bear. It sets out to teach the rules through scenarios dedicated to each rules section so that participants may slowly build up their acumen and internalize the sub-systems. It’s a good way to teach but it’s not practical for most in the hobby. Earth Reborn requires dedication and work which will ultimately pay dividends like a broken slot machine, but you must put in the effort. It starts off explaining the core Order System, where you play a tile next to one of your characters and then spend some of your limited Command Points (CP) to take one of several actions on the tile. The Command tiles themselves are quite varied, and allow you to spend different amounts of CP to perform actions more effectively and increase the likelihood of success.\nMovement and shooting comes next and are pretty simple to grasp as everything is measured orthogonally and core concepts like line of sight are reminiscent of similar affairs many gamers would have experienced prior. Attack rolls are handled through custom dice that generate various amounts of hits that are needed to overcome the opponents own hits and armor in melee, or just their armor when firing a weapon at range.", "504" ], [ "It’s not altogether complicated but there is depth here, particularly once you start including equipment and weapons which modify rolls and perform differently. You also have added interaction from firing arcs and different amounts of damage depending on where the target is in relation to which way your character is facing. Some people would argue this is needlessly fiddly; I would argue it is simply awesome. When you look at <PERSON> melee arc, and realize he is just as effective on his left side as his front (due to having a huge buzz-saw left hand) you realize the amount of cleverness in the design is inordinately high.\nThe game is simply made of an extraordinarily large portion of these small touches of ingenuity as the attention to detail is phenomenal. The Search mechanic is a prominent example, as many games simply have you roll some dice and draw a card to claim your reward. <PERSON> says “hell no”, as Earth Reborn requires you to manipulate the Search deck with a sub-system that can only be described as brilliant. You roll dice which give you search points and allow you special actions such as shuffling the deck or flipping it over. You’re allowed to spend your search points to purchase the card on top as long as the icons on the card match the room you are searching – which means you can only pick up an Assault Rifle if you’re searching the armory or the Declaration of Independence if you’re searching a Command icon room. You can only buy the top card, so you must manipulate the deck to view additional cards and find an item to either accomplish your objective or aid in your ability to vanquish the enemy. Adding to the utterly high degree of awesomeness is the fact that the cards are double-sided and sometimes you’ll need to finagle the deck to flip cards over to find that needed piece of equipment. It’s just sheer joy and you’ll find yourself going out of your way to perform a Search simply to interact with this incredible mechanic. I’d almost go so far as to say it’s my favorite mechanic of any game I’ve ever played as it’s simply that damn good.\nRight behind Searching is the mind-blowing icon driven action system peppered throughout the game. The mechanic is dubbed the “Iconographic Phrasing System” (IPS) and typically consists of a single line of symbols that denote an action or effect you can trigger at the location. Fans of Race for the Galaxy will have no problem quickly digesting this common sense notation which is often highly logical and easily organized. This may, however, be a turn-off of significant proportions for some and is one of the contributing factors of the design’s difficulty in attracting a large popular audience.", "366" ], [ "In many ways Claustrophobia is the perfect two player game. It’s asymmetrical. It offers somewhat deep tactical choices yet is easy to digest. It boasts astounding variety through a multitude of scenarios and effects. If you would have asked me in 2010 how the game could possibly be improved I would have shot back – “Improved?”. Then De Profundis came out and my world was rocked. In 2014 it’s happened again with Furor Sanguinis, which has taken things in an altogether different direction.\nFuror Sanguinis includes a new unit, Kartikeya, 3 new tiles and a group of new tokens used across its 6 scenarios. Kartikeya is an enormous Demon-Sized bipedal lizard whose race is known as Squamata. He was born human and has been warped into the bestial monstrosity he is now while taking up residence in the tunnels below New Jerusalem. He is searching for freedom and evolution by consuming the essence of Demons as he works his way up the hierarchy of hell. It’s a compelling and bizarre narrative that unfolds across a half dozen scenarios that follow this horrific endeavor.\nKartikeya is first and foremost a beast. If you ever wanted to <PERSON> smash your way through the dungeon, tossing aside Troglodytes and Humans like discarded toys, then this is the expansion for you. Mechanically he functions like a cross between the Demon and Humans, rolling a dice pool to assign to areas that build up wounds as the game progresses. You are able to beef up his combat ability or boost his speed and cunning. He’s more flexibile than either previous faction and feels well bulked out as a single threat with a dynamic and nuanced play style that affords the ability to tackle many problems in creative fashion.\nThe Squamata’s Instinct board is similar to the Demon’s board but is divided up into sections corresponding to specific body parts.", "366" ], [ "The head has several abilities including one that offers Frantic, one that allows you to roll additional dice in the Instinct phase, and one that makes you Impressive. The body allows for Regeneration and Elusive. Arms control Combat ability and the Legs buff movement. It all works rather seamlessly, offering those juicy signature tactical dilemmas of whether you go all out offense, worry about speed and pushing towards the goal, or sit back and take things slow while you maintain a safer crawl.\nWhen you receive damage you must assign the damage to a specific body part. Each section can take 3 or 4 wounds and once a body part has taken its maximum number you can no longer assign dice to abilities in that area or heal wounds there. Because you can heal 1 wound a turn, the Demon or Human player can’t quite push for the death by a thousand cut strategy that works on the Humans. The enemy will want to pick and choose his offensive moments, looking to overwhelm and provide a torrent of damage to mitigate the slow drip of the Squamata’s healing powers. It’s an interesting pace that kind of mixes up the feel of the base game and really provides for a distinct combat experience.\nOne of my favorite elements of the previous expansion was the bevy of new scenarios that stretched the boundaries of the mechanics. Likewise, Furor Sanguinis features scenarios that are a touch more creative and interesting than the base game. You have opportunities to push through like a beast just slaughtering every foe in your path as you look to confront a tough new <PERSON>, you also have missions where you will be navigating a delicate maze looking to locate Troglodyte eggs, one scenario even has you fielding chained Human slaves that can’t venture more than a tile away from the <PERSON> (think <PERSON> but the Walkers actually have jaws). They’re varied, interesting, and leave you wanting to replay them to attempt different strategies and approaches.\nSome of the early buzz abounding this expansion in the rumor mill was that it would allow for the possibility of 3 players. This has always been a desire bandied about by a vocal group and it’s certainly not one I would begrudge. However, the initial talk is not altogether accurate as there is only a single scenario that features all three factions and supports a possible three participants. The mission itself never references three players though and it assumes the Squamata player will control the new lizard-beast as well as the Redeemer’s forces. It works fine with the full complement of three players but this is not at all an expansion geared towards adding a third player to the table, rather, that is an added benefit of a single scenario, albeit one that is very engaging and perhaps the most memorable of the six.\nWhat is quite fascinating about the three faction scenario and those that follow it is the winding narrative of <PERSON> and how he interacts with the previous two groups.", "884" ], [ "Everyone loves a good bar. Bottom-shelf shots, double-fisting beers, and countless hours of brawling while calculating THAC0.\nThis concept began as a re-working and modernization of the classic 1980 Yaquinto title Swashbuckler. <PERSON> and family eventually came to the realization that the result was a different animal altogether. The Dragon & Flagon was born and gamers worldwide-well, at least those who attend my game nights-rejoiced.\nThis is a mechanically solid programming game with a very light and inviting theme. Don’t let the cheery artwork and cutesy 3D scenery (seriously, have you seen those mugs and chairs?) hoodwink you into thinking this is a light gateway game though. The engine behind the body has a stable full of horsepower and the entire package is quite clever.\nThe Dragon & Flagon - where the only thing that's spilled more than beer is blood.\nThe goal is to amass the most fame by bashing each other over the head with scenery. Every blow you land steals fame from the target and the hostess with the mostest at the final bell is the lord of the barroom brawl. It’s a simple concept executed with a relatively straightforward action programming structure.\nPlayers have a large hand of cards with mostly common actions and a few unique ones only their character can perform. In between each time segment, effectively a round, you program a card face down into your first and second action spaces. When your turn pops up you flip your first card and execute it.\nAfterwards you slide your second card down to the first slot and program a new card in position two. Your character marker jumps forward a number of spaces on the time track depending on the maneuver you executed, and then you await your next action. The time track itself has a slight Red October vibe, but thankfully the execution is much more interesting here.\nA cast that actually represents the variety of everyday life.\nI will say that for a silly and over the top theme the mechanical weight is heavier than you’d expect. Filling empty action slots, maneuvering a large hand of cards, fiddling with the time track, and managing lingering status affects-all of these can come across as occasionally cumbersome and take you out of the action. It gives the game a procedural feel at times where the action is segmented out in small dollops.\nFortunately the action is worth the wait. You pick up chairs or mugs, hop atop tables, literally yank rugs out from under drunk bystanders, and swing from chandeliers.", "755" ], [ "Any game where I can climb a table, get pelted by a thrown stein, and then leap off to kick the Paladin in the head has my vote.\nThe trick is that the conclusion of each action can be extremely satisfying and dramatic. You can pull off interesting combos like boasting your superiority and then landing a risky flying kick. The points pour in and your enemies lay in a pool of tears and ale.\nAdding to the flair is the very powerful unique special card each character possesses. You can only unlock this card if you grab the magical dragon flagon located at the center of the room. You’ll have to dive across tables, duck a few blows, and produce some fancy footwork to grab the thing, but it will certainly be worth it.\nWhen you trigger those special action cards you feel like a super hero. You’ll blast up a part of the bar with a cannon shot, react with blazing speed and avoid programming, or bring the power of god down upon the patrons. The rest of your crew will wish they slipped out before last call.\nBeyond those awesome dramatic moments the design ultimately triumphs because it knows how to pull off action programming, at least in a 2016 sense. The key to this genre is producing moments of chaos without feeling punishing. You need to maintain the balance between effectiveness and incompetence which produces humorous outcomes. Serving both in even doses is as difficult as balancing on one foot while half the bar is pelting you with mugs.\nThe Dragon & Flagon succeeds in this aspect because it’s undeniably smart. It keeps the programming to only two action cards so that you can continually adjust. When dazed from an attack, or when profusely chugging beer if you’re the pirate, you have to fill a third action slot. That amount of severity is perfect as it’s a penalty to have to think and plan ahead amid a scene full of chaos. Yet you never are excluded from participating or affecting the playing field.\nEven when you script an action that is not allowed, such as a throw when you don’t have anything in your hands, the game never slaps you down. You merely discard the card and progress one space on the time track, ready to act immediately again in the next round. It’s clever and refined and just feels right.", "237" ], [ "Cave Evil is raw and brutal. It features exceptional black and white artwork fused with mechanics that bury the player in the dripping blood and ichor of theme. It’s the only game that has a trailer and an online radio stream dedicated to setting the atmosphere. It’s weird, obtuse, and unforgettable. It’s the type of game <PERSON> could have designed if he didn’t spend his entire day planning his next escape from his maximum security Norwegian prison.\nRight off the bat the unique and awe-inspiring tone is set when you get your dirty claws on the box. The large and eerie Black Metal-esque cover grabs your attention. When you tear the shrink and fondle the components you will quickly realize this is a labor of love, manufactured 100% in the United States with unparalleled attention to detail. The quality of the components is not on par with FFG, but they are solid and functional and overcome their minor deficiencies with unique presentation. Every single piece of artwork (including 300+ cards all bearing unique illustrations) morph into this whole that is greater than the sum of its parts. It’s really something and you must experience this game in person, as descriptions and images don’t do it justice.\nIn Cave Evil you will play a Necromancer, able to summon vile and hideous creations to send down the dark corridors of eternal darkness and root out your enemies. You collect resources of Metals, Gore, and Shadowflame so that you may invoke creatures, spells, or items from your hand of cards. These legions of hell form squads of several combatants which allow you to maneuver the tunnels and expand your dominance. Each squad is granted a single action in addition to moving each turn, and is typically utilized to either press the attack or excavate the cave system forming the board.", "728" ], [ "Squads will dig and carve out the malicious earth, opening new passageways which boast wandering monsters and abundant resources. They will bribe or fight the neutral beasts and gather these resources to return to the <PERSON> to feed the machine and fuel the process of bolstering your horde.\nThe game comes with a paper map, displaying the hex-grid which forms the foundation for the tunnel tiles to be placed. A wide array of tunnel shapes and sizes is featured, and you will never quite be able to predict what will appear when your <PERSON> and Bloated Worm tear down the wall and reveal a new discovery. It’s exciting and visceral as you draw an Excavation Card which will tell you the tile to place and often prod you to make a spawn roll – which often results in Metal/Gore/Shadowflame being placed but will occasionally provide for a draw of one of the four Conjuration Decks which could mean a wandering monster or even an ancient artifact is discovered. It is immensely satisfying to tear through the corrupt earth and come across a Demon Prince that you beat to the ground and force to join your war-band.\nThe game is bloated with these awesome, unpredictable moments and peppers you with a constant stream of surprises like a giddy child ripping through a stream of presents on Christmas morning. You are repeatedly presented with situations that bring back memories of that feeling of excitement laced with tension in your gut when you open a booster pack to your favorite CCG. Akin to that Glory To Rome quality of game-breaking combos, you will see new and wondrous creatures nearly every time you play, and you will work hard to pump out a wall of corpse eating machines to wreak havoc on your enemies. You will have games where you build a bomb and throw your Necromonk into your enemy’s defenses so that you can blow a hole and charge through with your Insanity Demon. You will see <PERSON> teleport his squad adjacent to <PERSON> in a suicide run of mass proportions. You will be charged by an Undead Dragon and then activate the Ice Dead Sorceress’ power to take control of the beast and force him to join your side. The narrative is consistently strong and is built upon this framework that pushes out memorable outcomes like a hen excreting golden eggs.\nOne of my favorite elements of Cave Evil is the Awakened Evil. As you summon creatures and eat through turns, the Blood Eye marker will move around the map, following a linear track. When it reaches the end of the track, the Awakened Evil will appear and your ferocious <PERSON> will be hurled to the wolves as one of several abominations of epic proportion tear up the cave system. The Awakened Evil is drawn from a deck of cards and consists of such glorious creations as the Darkest Evil Bitch which hunts down the weakest players first, the Eternal Evil Emperor who boasts stats twice as good as the best rare creatures in the game, and several more horrifying creations which will have you clenching your sphincter in anticipation for your oncoming downfall.", "728" ], [ "These days, it’s not uncommon to find card games that disguise themselves as something much more. They push the envelope and redefine how complex, strategic, and/or thematic a card game can be. Guillotine is the antithesis to these, a basic card game that makes no pretensions. Two decks of cards, a toy (non-working) head-chopper, and that’s all it needs to be a cut above your average filler.\nComponents: See above. The two decks of cards – the action deck and nobles deck - are colorfully designed (with tongue firmly in cheek) on decent quality stock and nicely coated. (Despite all the execution, there is no ‘die’ to roll). Not much more to say on that!\nTheme/Object of the game – You are one of the executioners during the French Revolution just trying to make a name for yourself by executing the highest ranking nobles (based on point value) in line. Of course, other executioners are also out for the fame and fortune you desire. Your job is simple: behead the first noble in line at the end of your turn. But playing the right action card at the right time can make all the difference in the world. The person with the most points at the end of three days of executions is the winner.\nRules: Dirt Simple. You start out with five action cards in your hand and 12 nobles in line to lose their head during day one of executions. You have the option of playing an action card at the beginning of your turn.", "237" ], [ "If so, you execute (pun intended) the action immediately. Whether you’ve played an action card or not, you then must behead the first noble in line, then take another action card from the deck. When there are no more nobles in line, lay out 12 more for the next day. The game is over after three days of executions. Any exceptions to these rules are printed on the cards themselves.\nGameplay: I’m not just sticking my neck out when I say that this is where the game shines. The action cards in your hand allow you to do a variety of things – rearrange the line (or prevent people from rearranging it), add or subtract nobles to the line, assess penalty points to other players, reverse the order of nobles, etc. While this may not be the most strategically challenging exercise, it is unpredictable and fun. Sure, there’s a hefty amount of luck involved, but having a few decisions on which is the best play at any one time is just enough to give you bragging rights when you win.\nGood Stuff – This is a card game that plays in about 15-20 minutes and is a great filler game. Selling for about $15, it’s also a pretty good deal. You can always play fewer hands (days) than prescribe, or reformat the game to make the game longer (but remember, there are only so many nobles cards). Having no small parts also makes this very portable.\nBad Stuff – The game can wear out its’ welcome if it’s played too much, and the theme might be a turn-off for those who are easily offended.\nFinal Words. Guillotine is a wonderful find – a multi-player filler game with a warped sense of humor and an air of unpredictably. It’s not very deep nor is it grandiose, but is a lot of fun. I can see myself picking up this game and keeping it in the car to play at coffee shops or wherever the opportunity presents itself.", "237" ], [ "This review was originally posted at Player Elimination, my weekly board game editorial site.\nYou couldn’t miss it. As I walked up to my front porch, slouched and tired from not enough sleep and more than enough work, the large package was sitting there. This isn’t an unusual sight as cardboard shipping boxes containing cardboard gaming boxes arrive weekly at my suburban dwelling. This one was different because it was unexpected.\nI hurried inside lifting with my legs instead of my back, and laid the thing out on my dining room table with a pietistic moment of silence.\nA careful slice of the knife and there it was, that sleek black and gold cover staring me in the eyes with all the atmosphere of an <PERSON> directed game of chess.\nThis happens often. I toss a wad of cash into the pot of a Kickstarter campaign and several years later a game arrives unexpectedly. It’s like a subscription box that delivers once a year and takes your arm as recompense.\nYou may have heard of the 7th Continent (cue church bells, doves, and <PERSON>). It raised eight million dollars over two crowdfunding campaigns and has received much acclaim. As an experience it abandons players on an island and has you working together to lift a cryptic curse. And everyone absolutely loves it.\nFor good reason too. In many respects this is the ultimate exploration game as you cut through jungle, stumble through snow, and snarl in the face of the weirdest of beings. It’s captivating and overwhelming in the sheer amount of content you can discover over the course of play. One could literally set fire to the rest of their collection and dedicate themselves to the 7th Continent for the rest of the year. Probably the rest of all of your years.\nAlthough I don’t actually recommend that.\n[record scratch]\nNever have I so thoroughly committed myself to a game and felt so conflicted. This monstrosity in a box has provided me with double digit hours of wonderful discovery and adventure. It’s provided some really standup moments of shock and it continually surprised me with the elegance of its core ‘push your luck’ mechanism. In short, it’s a beautiful piece of design and an unparalleled experience – for 12 hours or so.\nThe 7th Continent thematically exists as a sort of heartbreak simulator. It accomplishes what Fog of Love couldn’t in that it presents a genuine emotional journey of courtship, love, consummation of that love, comfort, annoyance, aggravation, hate, and eventually divorce.", "504" ], [ "Yeah, that’s quite a bit of steps to unpack and work through. Relationships are complicated, yo.\nThe problem with a design predicated on exploration is that you need something to explore, something that will eventually be fully discovered and lose its purpose. Think about that for a moment. When the premise of your creation’s fun is in the process of discovery, the lifespan is outright limited. You’re working towards something, and that something is likely an unsatisfied ending. The damn finish line is the knife that’s going to kill you, not the 20 mile long trek.\nPeople like to throw around that special phrase ‘it’s not about the destination, it’s about the journey’. Usually to sort of couch disappointment in a revelation that’s not up to snuff. I watched Lost, I know disappointment.\nThe 7th Continent’s solution for this problem of terminus is to throw it all at you. Not just the kitchen sink, but the loofah, the hand towel, the tiles, and even the blackened grout between them. What feels like the entire run of Dominion, Legendary, and Thunderstone is all crammed into a single box where you must meticulously curate and file each card so as to make retrieval during play minimally painful. By giving you so damn much to explore and wade through, you’ll never hit that unsatisfying end-of-the-line where you look back and question your life choices – at least that’s the theory. And while everything is fresh and exciting, that pain of leafing through cards and maintaining a perfectly organized library will be subdued and easily covered up. Eventually fresh and exciting turns to rote and monotonous, end of the journey or not.\nThe island feels enormous in the early days. You’ll push through alien territory and encounter bizarre vegetation and bizarre-er lifeforms. You’ll hit breathtaking pieces of geography and your mind will race with possibility. It all feels so damn wide open and refreshingly free. You can do whatever you want and go wherever you’d like.\nThat’s the premise at least.", "558" ] ]

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[ [ "Auto-Closing Stacking Drawers for 20mm V-Rail Framed 3D Printers\nIntroduction: Auto-Closing Stacking Drawers for 20mm V-Rail Framed 3D Printers\nUPDATE: 07 April 2021:\nSTL files posted, see last step.\nPROJECT SUMMARY:\nThis project was inspired by:\n1. Instructables Member <PERSON> and his Multicolored Organizer Project\n2. Thingiverse member <PERSON> and her Stacking Drawer Design\nMy mashup of those two ideas aims to create ample and organized space for small items all within easy to reach, easy to access, and easy to identify storage drawers intended for 3D printers using 20mm V-Rail as part of their frame like my Creality Ender 5 Pro.\nOnly two items must be purchased (skateboard wheel bearings and clear plastic rounds), while the rest of the parts are created by the 3D printer itself or should be on hand (like rubber bands). Auto-Closing is accomplished by a standard size rubber band and attachment to the V-Rail is through standard 5mm T-Nuts.\nThis Instructable is an entry in the Simple Machines Contest. Please vote if you like it.\n(This auto-closing drawer design is an example of a simple machine featuring Elastic Energy, Torque, and Rotational Work. It best aligns with a \"Wheel & Axle\" simple machine per the contest guidelines.)\nTABLE OF CONTENTS:\nProject Summary\nSupplies\nStep 1: Requirements & Desirements\nStep 2: Design\nStep 3: Illustrated Parts List & Features\nStep 4: 3D Printing\nStep 5: Post Processing the 3D Printed Parts\nStep 6: Build Step I: Gather all Parts\nStep 7: Build Step II: Install Windows\nStep 8: Build Step III: Mount Base to V-Rail\nStep 9: Build Step IV: Install Pivot Pin\nStep 10: Build Step V: Install First Bearing\nStep 11: Build Step VI: Install Drawer\nStep 12: Build Step VII: Install Second Bearing\nStep 13: Build Step VIII: Attach Rubber Band\nStep 14: Build Step XIV: Repeat Steps I-VIII for Next Level\nStep 15: Validation\nStep 16: FINISHED\nSupplies\nMATERIALS:\n1. Skateboard Bearings (608ZZ) (Quantity 2 Per Drawer)\n2. 40mm Clear Acrylic Rounds (Quantity 4 Per Drawer)\n3. 5mm Panhead Screws & T-Nuts (Quantity 2 EA Per Drawer)\n4. Rubber Bands (Size #32 - 3\" X 1/8\") (Quantity 1 Per Drawer)\nTOOLS:\n1. 3D Printer\n2. Allen Wrench For The 5mm Screws\n3. Standard Shop/Hand Tools For Post Processing The 3D Prints (Supports Are Required)\nSOFTWARE:\n1. Autodesk's Fusion 360 (Used To Create The Design)\n2. Ultimaker's Cura Or Other Slicer (For Slicing The Files To Your Specific Printer)\n3. Luxion's Keyshot (Used To Create Realistic Renders like the image with the Instructable Trademarked Logo)\n4.", "858" ], [ "Corel's Video Studio (Used to Create Short Time-Lapse Videos From Still Shots)\n5. Adobe's Photoshop (For Photo Editing)\n6. Microsoft's PowerPoint (For Image Labeling)\nStep 1: Requirements & Desirements\nHere's a list of requirements and desirements in no specific order:\n1. Drawers can not impede the operation of or normal access to the printer\n2. Drawers should have a feature to keep them closed\n3. Since they stack, having a feature to see what's inside would be desirable\n4. Minimize need for purchase parts\n5. Maximize number of 3D printed parts\n6. Minimize cost\n7. Use a variety of filament colors to maximize visual appeal (or use for categorization, ex. Blue Drawer = Q-Tips)\n8. Include a feature to temporarily hold a drawer in the open position\n9. Size the drawer such that the design can fit on a variety of printers (not be specific to only my printer)\n10. Size the drawer's internal space to fit some of the most common tools frequently needed while 3D printing\n11. Make the design compatible to be either Left or Right Handed\nStep 2: Design\nI continue to enjoy working with Autodesk's Fusion 360 for all my personal design projects. (I wish I could use it for work, but am still stuck with CREO). Even with the great value of the free hobbyist license, I use it so much and wanted some of the extra features that come with a full license I recently made the purchase.", "737" ], [ "Pinky - Cheap Computer for Remote Learning\nIntroduction: Pinky - Cheap Computer for Remote Learning\nPROJECT SUMMARY: Semi-portable (still needs wall power) cheap computer that's ideal for kids to use for remote learning at home. Its based on the Raspberry Pi computer and a specific small monitor by HP. It can easily be moved around your home to suit the needs of your family and then moved out of the way (like off the kitchen table) when not needed.\nThis project is an entry in the Anything Goes Contest. Please vote if you like it.\nSo this is one of those projects that just comes out of nowhere. This was entirely unplanned and unneeded, but a few things all fell into place with the right timing and thus \"<PERSON>\" was born. Here's the culminating list of things that led to the project:\n1. Got several rolls of pink PLA filament (3D printing material) super cheap. Nothing against pink (I actually like it), but I just figured I'd use it mostly for prototyping.\n2. Black Friday deal on a mechanical keyboard that I've always wanted to try, but the best deal was the pink model. (Turns out I do NOT like mechanical keyboards.)\n3. I had been trying to get Octoprint to work on my 3D printers, but gave up, so I had a Raspberry Pi computer just sitting unused\n4. My employer provided work from home kits that came with monitors, but in my home office I have a larger monitor. So this monitor was sitting unused as well.\nNOTE1: I realize if you purchased these exact items to replicate this project it would not be cheap, and the money could be much better used to simply buy a older used laptop computer. That said, my intention with this Instructable is to show how to piece together a usable computer with items you may already have on hand and how you can 3D print add-on parts to make it portable and tidy when not being used.\nNOTE2: I won't go into setting up the computer itself. There are tonnes of resources (primarily raspberrypi.org) and Instructables (there's even a few entered in this same contest) on setting up Raspberry Pi software.\nSupplies\n1. Small Computer Monitor. Shown here is Model Number 1JS09A4#ABB (HP 24\" LED WUXGA IPS Z24N G2)\n2. Raspberry Pi Computer. Shown here is the Model 4 with 8GB RAM and a clear case from Canakit Amazon Link\n3. Power Cord (This will power the Raspberry Pi directly from the monitor, no AC/DC converter needed)\n4.", "936" ], [ "Short Micro HDMI To Standard HDMI Cord Amazon Link\n5. M6 Allen Head Bolts and 1 Locking M6 Nut\n6. M3 Screws and Nuts\n7. Keyboard (wired or wireless)\n8. Mouse (wired or wireless) Amazon Link to one shown here\n9. Heavy Duty Double Sided Tape (Gorilla or 3M brand)\n10. IPA (For cleaning surfaces before applying the tape)\n11. OPTIONAL, USB Camera, and Wired or Bluetooth Speakers\nTOOLS:\n1. 3D printer with standard PLA filament\n2. Standard shop tools\nStep 1: Carry Handle Overview\nSo this monitor has a unique design for the center pedestal. They even sell a small form factor workstation that mounts directly to it (Last Image). I leveraged that in designing a two-piece assembly that clamps the upper portion. The long arm and its angle are designed to balance the weight of the monitor while lifted and also to allow the monitor to meet its full range of motion.\nStep 2: Carry Handle Design\nAll designs were done in Autodesk's Fusion 360 (First Image), sliced in Ultimaker's Cura (Second Image), and printed on Creality printers.\n3D prints were done at 0.2mm layers and 50% infill (this is high but you want a high value for the strength).\nSTL files below.\nStep 3: Carry Handle Installation\n1. Attach the handle to the upper arm part with a bolt and locking nut. Do not over-tighten. The handle should be free to rotate.\n2. Start the two bolts on the forward facing side of the upper arm part into the rear part, but leave loose (First Image)\n3. Bring the two parts together to engage the recessed features on the monitor's pedestal (Second Image)\n4. Install the remaining four bolts from the rear and secure all six bolts (Last Two Images)\nNOTE: The front two bolts require an L shaped allen wrench or ball-end driver since the monitor's panel is in the way. Or you can detach the monitor from the base and reattach later.", "116" ], [ "Designing a Simple 3D Printed Rubber Band Car Using FreeCAD\nIntroduction: Designing a Simple 3D Printed Rubber Band Car Using FreeCAD\nAs a retiree, I have designed and published 3D printable mechanisms for entertainment, educational and hobbyist purposes here and on other websites using Fusion 360, as well as have provided free consulting to local companies with their use of Fusion 360. Changes to the Fusion 360 \"Personal\" version I use have made it difficult to support local companies with the Fusion 360 \"Commercial\" version they use, so we decided to try FreeCAD.\nMy first foray into FreeCAD is a redesign of my Fusion project \"Designing a Simple 3D Printed Rubber Band Car Using Autodesk Fusion 360\". So if you're interested in designing with FreeCAD, stay tuned as I upgrade some of my previous designs from Fusion to FreeCAD, and create new designs as well! I just need to find a way to upload the FreeCAD files here, as they were rejected, even in zipped form.\nAs with any 3D printed mechanism, prior to assembly, I test fit and trim, file, drill, sand, etc. all parts as needed for smooth movement of moving surfaces, and tight fit for non moving surfaces.", "737" ], [ "Depending on you printer, your printer settings and the colors you chose, more or less trimming, filing, drilling and/or sanding may be required. Carefully file all edges that contacted the build plate to make absolutely certain that all build plate \"ooze\" is removed and that all edges are smooth. I used small jewelers files and plenty of patience to perform this step.\nAs usual, I probably forgot a file or two or who knows what else, so if you have any questions, please do not hesitate to ask as I do make plenty of mistakes.\nDesigned using FreeCAD, sliced using Ultimaker Cura 4.7.0, and 3D printed in PLA on Ultimaker S5s.\nSupplies\n* \"R20\" sized O-Rings (25mm ID, 3.5mm Section).\n* Thick cyanoacrylate glue.\nStep 1: Wheels.\nThis video illustrates how to use FreeCAD to design and extrude the wheels.\nStep 2: Axles.\nThis video illustrates how to use FreeCAD to design and extrude the axles.\nStep 3: Chassis Sides.\nThis video illustrates how to use FreeCAD to design and extrude the chassis side.\nStep 4: Assembly.\n3D printing and assembly of this model is quite easy.\nI printed two \"Chassis Side.stl\", two \"Axle.stl\" and four \"Wheel.stl\" at .15mm layer height with 20% infill.\nNext, I pressed the two \"Chassis Side.stl\" together and if loose applied small drops of thick cyanoacrylate glue.\nThen I stretched the O-Rings around the wheels, two O-Rings for each wheel.\nFinally, I positioned an axle in the chassis assembly then pressed two wheel assemblies onto the ends of the axle. If the wheels are loose on the axles, again apply small drops of thick cyanoacrylate glue, then repeated this process with the remaining axle and wheels.\nApply the rubber bands as presented in the original video, then off you go!\nAnd that is how I designed a simple 3D printed rubber band powered car using FreeCAD.\nI hope you enjoyed it!", "116" ], [ "3D Printed Bracket Accessory for Nite Ize HandleBand Universal Smartphone Mount\nIntroduction: 3D Printed Bracket Accessory for Nite Ize HandleBand Universal Smartphone Mount\nI purchased a Nite Ize Handleband Smartphone Bar Mount at REI. I found it to be simple, effective and very easy to use on my road bike. In fact, it was such a simple concept that I wanted to extend its application.\nThe problem is simple: although the Handleband works great, it's only designed to attach to a shaft or bar. Worse, it can only properly attach to shafts with a narrow range of circumferences. This is a limitation.\nInstead of being to be mounted to just a handlebar, I thought it would be cool to create a bracket for the handleband to slip on to and grip firmly. With bracket extensions, the handleband could attach to pretty much anything. In other words, this bracket is simply a translation from the Handleband form factor to any other surface.", "668" ], [ "For my purposes, I want to fasten the bracket to a flat surface and a tripod to take time-lapse videos of my 3D prints with my Pixel smartphone. Why purchase a new tripod phone holder when you can adapt the Nite Ize handleband to this application--and it'll work even better!\nSupplies\n* Nite Ize Handleband Universal Smartphone Bar Mount or some similar product\n* Access to a 3D printer\nStep 1: Download the STL File. Modify It, If You Want.\nI designed this bracket in TinkerCad (free online CAD program). You can download the file through this Instructable. You can take my file and modify it if you would like. For example, you may want to create a mounting bracket to attach the handleband (and therefore your phone!) to some outdoor recreation vehicle with a curved surface. The possibilities are endless!\nStep 2: Print the Bracket.\nOnce you download it, use your software package of choice to make any modifications (printer specific settings, infill, etc.) I used Cura and Dremel 3D Idea Builder, which are both available for free.\nStep 3: Enjoy! Use the Bracket to Mount Your Smartphone Anywhere!\nNow you can use the handleband and bracket to mount your camera anywhere and in any position--not just on the right sized bar! Yay!", "646" ], [ "A 3D Printed Animated Angel Christmas Tree Topper.\nIntroduction: A 3D Printed Animated Angel Christmas Tree Topper.\nI designed \"A 3D Printed Animated Angel Christmas Tree Topper.\" for our 2020 Christmas Tree.\nThe model may be assembled without motorization for a static tree topper or centerpiece, and may also be illuminated using an LED from a 3VDC \"flickering tea lamp\".\nAs usual I probably forgot a file or two or who knows what else, so if you have any questions, please do not hesitate to comment as I do make plenty of mistakes.\nDesigned using Autodesk Fusion 360, sliced using Ultimaker Cura 4.7.0, and 3D printed in PLA on Ultimaker S5s.\nSupplies\n* 28AWG Stranded Wire.\n* Soldering iron.\n* Solder.\n* Heat shrink tubing.\n* Thick cyanoacrylate glue.\nStep 1: Parts.\nI acquired the following parts:\n* One N20 6VDC 50RPM gear motor.\n* One 3VDC power supply.\n* One 3VDC flickering tea lamp LED and diffuser.\nI 3D printed the following parts:\n* One \"Arm, Left.stl\", .1mm layer height, 20% infill.\n* One \"Arm, Right.stl\", .1mm layer height, 20% infill.\n* Two \"Axle, Arm.stl\", .15mm layer height, 20% infill.\n* One \"Base.stl\", .15mm layer height, 20% infill.\n* One \"Body.stl\", .15mm layer height, 20% infill.\n* Two \"Bolt, Mount, Motor.stl\", .15mm layer height, 20% infill.\n* One \"Cam.stl\", .1mm layer height, 20% infill.\n* One \"Guide, Yoke.stl\", .15mm layer height, 20% infill.\n* One \"Mount, Tree.stl\", .15mm layer height, 20% infill.\n* One \"Mount, WIng, Left.stl\", .1mm layer height, 20% infill.\n* One \"Mount, WIng, Right.stl\", .1mm layer height, 20% infill.\n* One \"Retainer, Mount, Wing, Left.stl\", .1mm layer height, 20% infill.\n* One \"Retainer, Mount, Wing, Right.stl\", .1mm layer height, 20% infill.\n* One \"Wing, Left.stl\", .15mm layer height, 20% infill.\n* One \"Wing, Right.stl\", .15mm layer height, 20% infill.\n* One \"Yoke.stl\", .1mm layer height, 20% infill.\nThis mechanism is a high precision print and assembly using at times very small precision 3D printed parts in confined spaces with highly precise alignment. I printed parts using the Ultimaker Cura 4.7.0 \"Engineering Profile\" on my Ultimaker S5s, which provides a highly accurate tolerance requiring minimal if any trimming, filing, drilling or sanding. However, prior to assembly, I still test fitted and trimmed, filed, drilled, sanded, etc.", "654" ], [ "all parts as necessary for smooth movement of moving surfaces, and tight fit for non moving surfaces. Depending on your slicer, printer, printer settings and the colors you chose, more or less trimming, filing, drilling and/or sanding may be required to successfully recreate this model. I carefully filed all edges that contacted the build plate to make absolutely certain that all build plate \"ooze\" is removed and that all edges are smooth using small jewelers files and plenty of patience to perform this step.\nThis mechanism also uses threaded assembly, so I used a tap and die set (6mm by 1) if required for thread cleaning.\nStep 2: Base Assembly.\nTo assemble the base, I performed the following steps:\n* Soldered 60mm lengths of red and black wire to the motor.\n* Pressed the motor into the motor mount on \"Base.stl\".\n* Pressed \"Cam.stl\" onto the motor shaft.\n* Placed \"Guide, Yoke.stl\" onto the base assembly, then secured in place with two \"Bolt, Mount, Motor.stl\".\n* Positioned \"Yoke.stl\" into the base assembly.\n* Secured \"Arm, Right.stl\" onto the base assembly using one \"Axle, Arm.stl\".\n* Secured \"Arm, Left.stl\" onto the base assembly using the remaining \"Axle, Arm.stl\".", "784" ], [ "CR-6 SE 3D Printer Improvements\nIntroduction: CR-6 SE 3D Printer Improvements\nUPDATE 23 JULY 2022:\nAdded a few native files for spool holders.\n07 JAN 2022:\nI get a lot of requests for the native Fusion 360 files. So I just posted them here for all. See Step 16.\nUPDATE 18 JAN 2021:\nA member requested a modified filament housing sensor housing to pair with an upgraded extruder. File is at Step 15.\nUPDATE 31 DEC 2020:\nA new version of the bearing pulley wheels has been added. I found a problem where they were losing their grip on the metal bearing. The new version should be slightly tighter when first installing and it also has a small hole added to allow a drop of glue to help keep them in place better. File is at Step 14.\nUPDATE 12 DEC 2020:\nMade a new version of the spool holder. Its universal so no need to change the setup when you move to a different filament spool size. File is at Step 13.\nUPDATE 30 OCT 2020:\nAdded STL files for a 33mm diameter spool holder that was requested in the comments section.\nLet me know if anyone else needs a different size. Files are at Step 12.\n_____________________________________________________________________________\nPROJECT SUMMARY: I'll go through a few glaring problems (IMO) with Creality's newest printer, show you my redesigned components, and lastly how to install it all so you too can vastly improve the usability of your CR-6 SE printer.\nThis is an entry in the Make it Move Contest! Please vote if you like it.\nPROJECT HIGHLIGHTS:\n1. Absolutely no drastic changes or permanent modifications to the printer are needed for this project. In fact, once you print all the new parts, the only thing done to the printer is to remove two screws (and then those same two screws are reinstalled.)\n2. The printer itself is used to make the parts needed\n3. Purchased parts are only 6 bearings, 3 screws, and one LED* ($10)\n(* No soldering or wiring needed. We'll just be using the clear plastic head of the LED)\nFor reference, here's the Kick Starter link that Creality used to promote and do the initial sale of the printers:\nhttps://www.kickstarter.com/projects/1001939425/cr...\nSupplies\n1. (QTY1) M8 Allen Head Screw, 50-65mm Long\n2. (QTY 2) M4 Allen Head Screw, 10mm Long\n3. (QTY 6) Standard Skateboard Bearings (608ZZ).", "116" ], [ "I got These\n4. (QTY 1) Standard 5mm LED\nTOOLS:\n1. Allen Wrenches for the M4 & M8\n2. Wire Snips to cut the leads from the LED\nStep 1: Problem 1: Side Mounted Filament Holder\nThis was the biggest issue for me. By mounting the filament spool holder to the side; the footprint of the printer is unnecessarily huge. This position (and the \"fold-away\" feature) almost doubles the required width space for the printer!\nNow, if you have the room, this may not be an issue whatsoever. For me, it meant the printer sat on the kitchen table, then the kitchen counter, then in front of the TV, and finally out to the garage, until I was able to finish making these modifications. It now sits next to my other printers in my small cramped office space.\nWhile my issue is minor as far as Creality is concerned, something that should be a consideration for Creality to assess is Printer Farms. Small companies may consider this printer as the foundation of a Printer Farm (several printers under one roof cranking out parts for the business). By making these modifications the linear printer density can be increased drastically. (For example: 5 printers fit side by side using my configuration versus only 3 if left in the factory configuration on a standard 8 foot long work bench.)\nMy custom designed parts eliminate this issue (or in the least provide an alternative option).\nStep 2: Problem 2: Filament Sensor\nThe automatic filament sensor is a new addition and a great selling point for this level and price range of printer. (The sensor is the part in the right side of the first image above with two screws holding it in place.)\nHowever it has a serious flaw. The Filament Guides, which are metal (brass most likely), have sharp edges. See second image above. That should be a soft radius not a chamfer. Only a few small prints in and I noticed a pile of filament powder that these sharp edges scraped off. (This is a case where cheap plastic parts would actually work better than going to metal. Better yet would be if they were made of Teflon.", "116" ], [ "DIY Studio Light/ Light Box\nIntroduction: DIY Studio Light/ Light Box\nHey Everyone what's up.\nThis is my DIY Studio Light Project\nWhich basically is a do-it-yourself studio light that is made from a custom 3D Printed body and a custom PCB which were both provided by PCBWay.\nQuestion\nIs it better to Buy an expensive Studio Light or Make your own DIY Studio Light with custom 3D Printed parts and PCB?\nWell, the goal for making this project was just that, I wanted to make a DIY Studio Light for my current \"Maker Setup\" as the lighting in my lab bench is not very great.\nCommercially available light costs above 50$ (good ones) but why spend money on them when you can make your own Studio Light, Body can be made from a 3D Printer and the circuit can be manufactured by a PCB manufacturer.\nIn this Instructables, I'm gonna show you guys how I made this DIY Studio Light in few easy steps.\nLet's Get started!\nSupplies\nThese are the things that I used for this built\n* LEDs (NICHIA JK3030 3V .2W LED)\n* 1.5 Ohms Resistance 1206 Package\n* 0.47 Ohms Resistance 1206 Package\n* 100uf Capacitor\n* 63uH Indictor\n* SS34 Diode SMA\n* DC Barrel Jack\n* Custom PCB (which was provided by PCBWAY)\n* Custom 3D Printed body (which was also provided by PCBWAY)\n* SIC9301A led driver IC x2\n* 12V DC FAN (Generic small one)\n* 12V SMPS Power Supply\nStep 1: Basic Structure\nMy goal was to make a DIY Studio Light completely from scratch to compete with existing light available in the market.\nThe reason for starting this project was the cost of the existing setup, Commercial Studio Light isn't exactly cheap and I need at least 2-3 Lights which would cost a lot so I made an easy-to-make Studio Light with custom PCB and 3D Printed Body.\nAlso, I'm using a generic FR4 PCB here. these LEDs produce a lot of heat so why I'm not using MCPCB (metalcore) instead of FR4 (fiberglass) for making a better-LED PCB that can disperse heat better than FR4 Board?\nYou see, I have added lots and lots of Via in this PCB, these Via will conduct heat from the top side and transfer that heat to the bottom portion which will result in Heat getting Disperse equally. Then at the backside, there's a 12V Mini DC FAN which cools down the PCB heat.\nApparently, Metal PCBs or MCPCBs are not $$$ wallet-friendly and if I have used a metal PCB in this project, I also have to use another FR4 board for LED Driver IC setup.", "982" ], [ "So I saved a lot by making a single PCB that contains the LEDs and Driver IC setup.\nAlso, the Body of this light is made from PET-G which is quite a durable plastic so overall, this DIY Studio Light can sustain heat.\nStep 2: Schematic\nThe main schematic of this project is attached above and as you can see, it's not very complex. it contains two LED Driver IC setups both with their LOAD (LEDs) connected separately.\nTheir Input side is connected with each other which is the common Input VCC and GND. we will supply 12V to these two terminals to run this board.\n(yes, I haven't used any Microcontroller or any Switching IC in this Circuit)\nStep 3: PCB Designing\nWith the above Schematic, I prepared the PCB in my CAD software.\nThe board outlines were already designed in the Fusion360, I used its measurements as a reference to make the PCB.\nI placed LEDs at the center of the board and maintained an equal distance between them, to keep things symmetrically accurate.\nAnd as you can see, I've placed lots of Vias in this PCB. Vias cover almost 70% of this PCB and they are here for Conducting heat as well as connecting one side with another side of the board.\nAnyways, after finishing the PCB, I exported its Gerber data and send it to PCBWay for samples.\nI Received the PCB in 7 days which is pretty fast, and it also came with a PCB Scale which was pretty cool (I have used my beans to get that scale though)\nI have to say, PCBs that I've received were great as expected, PCBWay, you guys rocks.\nCheck out PCBWay for getting great PCB Service for less cost!\nNext is the PCB Assembly Process.", "472" ], [ "A Simple 3D Printed \"Walking\" Mechanism.\nIntroduction: A Simple 3D Printed \"Walking\" Mechanism.\nI truly enjoy mechanisms, thus when a recent YouTube video appeared in my YouTube suggested video feed of a CAD animation of a simple walking mechanism designed by <PERSON> (https://www.youtube.com/watch?v=1ht3nz4YgGY), I just had to try to recreate his mechanism for 3D printing.\n<PERSON>'s mechanism was designed to be powered by torsion springs or rubber bands, but I decided to design a motorized version. After a long afternoon of design, 3D printing and assembly, \"A Simple 3D Printed \"Walking\" Mechanism.\" was the result. And as indicated in his video, the mechanism indeed powers over \"rough\" terrain with ease. Since originally publishing this model, I modified \"Side.stl\" to include a \"sawtooth\" edge for better traction over rough terrain, the new file is \"Side, Sawtooth.stl\".\nMy implementation of his design consists of eight unique 3D printed parts (twenty six total 3D printed parts as there are numerous duplicates), a motor, battery and battery connector.\nFor those such as I who truly enjoy mechanisms, I highly recommend checking out thang010146s website, his work is outstanding!\nAs usual I probably forgot a file or two or who knows what else, so if you have any questions, please do not hesitate to ask as I do make plenty of mistakes.\nDesigned using Autodesk Fusion 360, sliced using Cura 4.7.0, and 3D printed in PLA on an Ultimaker 3 Extended and Ultimaker S5s.\nSupplies\n* Double sided tape.\n* Thick cyanoacrylate glue (if necessary).\n* Solder and soldering iron.\nStep 1: Parts.\nI acquired the following parts:\n* One 3.7vdc 100ma Lithium Battery (https://www.adafruit.com/product/1570).\n* One JST PH 2-Pin Cable (https://www.adafruit.com/product/3814).\n* One N20 6VDC 100RPM gear motor (on line).\nI 3D printed the following parts at .15mm layer height, 20% infill:\n* Six \"Arm.stl\".\n* Six \"Axle, Side.stl\".\n* Three \"Axle.stl\".\n* One \"Base.stl\".\n* Six \"Bolt, Axle.stl\".\n* One \"Gear, Axle.stl\".\n* One \"Gear, Motor.stl\".\n* Two \"Side.stl\" OR Two \"Side, Sawtooth.stl\".\nPrior to assembly, I test fit and trimmed, filed, drilled, sanded, etc.", "654" ], [ "all parts as necessary for smooth movement of moving surfaces, and tight fit for non moving surfaces. Depending on you printer, your printer settings and the colors you chose, more or less trimming, filing, drilling and/or sanding may be required. Carefully file all edges that contacted the build plate to make absolutely certain that all build plate \"ooze\" is removed and that all edges are smooth. I used small jewelers files and plenty of patience to perform this step.\nThe mechanism also uses threaded assembly, so I used a tap and die set (6mm by 1) for thread cleaning.\nStep 2: Assembly.\nTo assemble the mechanism, I performed the following steps:\n* Positioned \"Gear, Motor.stl\" into \"Base.stl\", then pressed the motor into the base and gear.\n* Soldered the JST connector to the motor.\n* Pressed \"Gear, Axle.stl\" onto one of \"Axle.stl\".\n* Positioned the axle assembly in the base assembly, then secured in place with two \"Arm.stl\" and two \"Bolt, Axle.stl\".\n* Positioned the second axle in the base assembly then secured in place with two \"Arm.stl\" and two \"Bolt.stl\".\n* Positioned the third axle in the base assembly then secured in place with two \"Arm.stl\" and two \"Bolt.stl\".\n* Attached one \"Side.stl\" or \"Side, Sawtooth.stl\" to the base assembly arms on one side using three \"Axle, Side.stl\".\n* Attached the remaining side (or sawtooth side) to the base assembly arms on the remaining side using three \"Axle, Side.stl\".\n* Secured the battery to the base assembly using double sided tape.", "784" ] ]

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[ [ "Sum of size of distinct set of descendants $d$ distance from a node $u$, over all $u$ and $d$ is $\\mathcal{O}(n\\sqrt{n})$\nLet's consider a rooted tree $T$ of $n$ nodes. For any node $u$ of the tree, define $L(u,d)$ to be the list of descendants of $u$ that are distance $d$ away from $u$. Let $|L(u,d)|$ denote the number of nodes that are present in the list $L(u,d)$.\nProve that the sum of $|L(u,d)|$ over all distinct lists $L(u,d)$ is bounded by $\\mathcal{O}(n\\sqrt{n})$.\nMy work\nConsider all $L(u,d)$ such that the left most node on the level $Level(u) + d$ is some node $v$.", "743" ], [ "The pairs $u, d$ for all such $L(u,d)$ must be distinct and the sum of all $d_i$ will correspond to the number of nodes $x$ in the tree with $Level(x) \\le Level(u) + d$.\nThis is because if some sequence of nodes $v_1, v_2, \\dots v_k$ corresponds to the descendants of some node $u$ at a distance $d$ and the sequence of nodes $v_1, v_2, \\dots v_{k'}$ where $k' > k$ corresponds to the descendants of some node $u'$ at a distance $d+1$, then there must also exist a node $u''$ such that $L(u'', d) = v_{k+1}, v_{k+2}, \\dots v_{k'}$. This would also mean that $u''$ is not in the subtree of $u$ and thus there are at least $d$ distinct nodes in the subtree of $u''$ upto a distance $d$ from $u''$.\nIf the distinct distances are $d_1, d_2, \\dots d_k$ then, $n \\ge \\sum_{i}d_i \\ge \\sum_{i=1}^{k}i \\ge \\frac{k(k+1)}{2}$. =\n$\\implies k \\le \\sqrt{n}$\nAfter this I tried to show that there can be only $\\mathcal{O}(\\sqrt{n})$ distinct lists $L(u,d)$ so that I can then trivially obtain the upper-boud of $n\\sqrt{n}$ but I could not make any more useful observations.\nThis link claims that such an upper bound does exist but has not provided the proof.\nAny ideas how we might proceed to prove this?", "532" ], [ "tl;dr I wrote some solution but realized it is not perfect. Since I didn't want all this typing to go waste I figured I might post my observations here rather than splitting them in the comments.\nI think that the problem can be solved for any arbitrary $s,t$ and $x$ in $\\mathcal{O}(V+ E)$. In fact we can extend the problem to answer $Q$ queries of the form $(s,t,x)$ with $\\mathcal{O}(V+E)$ pre processing and $\\mathcal{O}(1)$ per query. I am having trouble completing step 6, but I am pretty sure that it can be done. Someone in the comments may know.\n1. Find all strongly connected components (scc) of the graph using Kosarjau's or <PERSON> algorithm. This step will take $\\mathcal{O}(V+E)$ time.\n2. Using a hash table, you can check if two nodes belong to the same stongly connected component in $\\mathcal{O}(1)$ time.\n3. If two nodes $u$ and $v$ belong to the same strongly connected component, then there exists paths both from $u$ to $v$ and $v$ to $u$.\n4.", "835" ], [ "Now what remains to be checked is if two nodes $u$ and $v$ do not belong to the same strongly connected component, does there still exist a path from $u$ to $v$.\n5. We will modify the given graph $G$ to a new graph $G'$ which we shall call the strongly connected component graph or scc graph for short. In the scc graph, each node corresponds to one strongly connected component in the original graph i.e. we compress all nodes belonging to the same scc to a single node. It can be proven that the scc graph is a Directed Acyclic Graph (DAG for short).\n6. Now our task reduces to check if there exists a directed path between $u$ and $v$ in the DAG. Topological sort can give an ordering such that for any path from $u$ to $v$, $u$ will appear before $v$ in the ordering. Thus we can check if index of $u$ in the topologically sorted sequence of vertices is less than that of $v$ in $\\mathcal{O}(1)$ but this method also gives false positives and this is where I am stuck.\n7. I feel that we can augment step 6 with some additional data to complete the algo. One method I was thinking of was to maintain some constant $K$ number of random topological sorts and if the inequality $index(u) < index(v)$ is true for all $K$ sequences then we can conclude with high probability that there is a path from $u$ to $v$.", "433" ], [ "Optimizing coin splitting - Is this algorithm as fast as I think?\nIn a recent exam, I've been asked to solve the following problem:\nThe problem\nTwo players play the following game: Given a sequence of coin values $v_1,\\ldots,v_n (n \\vert 2)$ the players take turns in taking one coin from either \"end\" of the sequence. The value of that coin is added to their score.\nPlayer 1 always starts. What is the maximum score that Player 1 can reach if Player 2 plays optimally (always minimizing their potential score)? What is the time-complexity of your algorithm? Prove your result.\nExample:\nGiven the coin sequence $1,1,3,1,1,2$ one of the best playing sequence for player 1 is (scores denoted as the second tuple):\n$$(\\lbrack 1,1,3,1,1\\rbrack,(2,0)) \\rightarrow (\\lbrack 1,1,3,1\\rbrack,(2,1)) \\rightarrow (\\lbrack 1,3,1\\rbrack,(3,1)) \\rightarrow (\\lbrack 3,1\\rbrack, (3,2)) \\rightarrow (\\lbrack 1 \\rbrack, (6,2)) \\rightarrow (6,3)$$\nThe best score player 1 can reach is 6.\nMy solution\nI'm just going to roughly outline my proof here, the formal correctness is not the point of this question. I'm more interested in the correctness of my asserted upper bound of complexity.\nFor the following I will use tuples to denote ranges of values.", "180" ], [ "$(i,j)$ specifies the value range $v_i,\\ldots,v_j$.\nWe iteratively create a DAG $G = (V, E, \\gamma)$ as follows:\nCreate a vertex $v$ named $(1,n)$. Create or refer to the previously created vertices $v_1, v_2, v_3$, named $(2,n-1), (3,n), (1,n-2)$ respectively.\nCreate the edges $e_1 = (v,v_1), \\gamma(e_1) = v_1$ and $e_2 = (v,v_2), \\gamma(e_2) = max\\lbrace v_1, v_n \\rbrace$ and $e_3 = (v,v_3), \\gamma(e_3) = v_n$. Iterate through the vertices $v_{\\lbrace 1,2,3\\rbrace}$ using a queue or similar to repeat the process until the sequence of coins denoted by the $v$ we iterate over is empty.\nThe number of edges in the created graph is bounded as follows: $\\lvert E \\rvert \\leq 3\\lvert V \\rvert$.\nThe number of vertices is denoted by the following sum: $1 + \\sum_{i=0}^{\\frac{n}{2}} 2i + 1 \\leq n^2$\nWe can determine the maximum score for player 1 by \"backpropagating\" the edge weights through the graph, which takes $\\lvert V \\rvert * \\lvert E \\rvert$ steps.\nThis makes the overall algorithm asymptotically require $\\Theta(n^2)$ steps\nThe problem I have with my answer is the upper bound for the number of vertices. I just pull that number out of thin air and my gut-feeling tells me that it is correct, but I might just be completely wrong.\nAssuming that this is indeed a correct way to calculate the answer to the question, is my time-complexity argumentation sound?", "172" ], [ "If for each node of a tree, the longest path from it to a leaf node is no more than twice longer than the shortest one, the tree has a red-black coloring.\nHere's an algorithm to figure out the color of any node n\nif n is root,\nn.color = black\nn.black-quota = height n / 2, rounded up.\nelse if n.parent is red,\nn.color = black\nn.black-quota = n.parent.black-quota.\nelse (n.parent is black)\nif n.min-height < n.parent.black-quota, then\nerror \"shortest path was too short\"\nelse if n.min-height = n.parent.black-quota then\nn.color = black\nelse (n.min-height > n.parent.black-quota)\nn.color = red\neither way,\nn.black-quota = n.parent.black-quota - 1\nHere n.black-quota is the number of black nodes you expect to see going to a leaf, from node n and n.min-height is the distance to the nearest leaf.\nFor brevity of notation, let $b(n) = $ n.black-quota, $h(n) = $ n.height and $m(n) = $ n.min-height.\nTheorem: Fix a binary tree $T$. If for every node $n \\in T$, $h(n) \\leq 2m(n)$ and for node $r = \\text{root}(T)$, $b(r) \\in [\\frac{1}{2}h(r), m(r)]$ then $T$ has a red-black coloring with exactly $b(r)$ black nodes on every path from root to leaf.\nProof: Induction over $b(n)$.\nVerify that all four trees of height one or two satisfy the theorem with $b(n) = 1$.\nBy definition of red-black tree, root is black. Let $n$ be a node with a black parent $p$ such that $b(p) \\in [\\frac{1}{2}h(p), m(p)]$. Then $b(n) = b(p) -1$, $h(n) = h(p)-1$ and $h(n) \\geq m(n) \\geq m(p)-1$.\nAssume the theorem holds for all trees with root $r$, $b(r) < b(q)$.\nIf $b(n) = m(n)$, then $n$ can be red-black colored by the inductive assumption.\nIf $b(p) = \\frac{1}{2}h(p)$ then $b(n) = \\lceil \\frac{1}{2}h(n) \\rceil - 1$.", "953" ], [ "$n$ does not satisfy the inductive assumption and thus must be red. Let $c$ be a child of $n$. $h(c) = h(p)-2$ and $b(c) = b(p)-1 = \\frac{1}{2}h(p)-1 = \\frac{1}{2}h(c)$. Then $c$ can be red-black colored by the inductive assumption.\nNote that, by the same reasoning, if $b(n) \\in (\\frac{1}{2}h(r), m(r))$, then both $n$ and a child of $n$ satisfy the inductive assumption. Therefore $n$ could have any color.", "610" ], [ "Consider the following problem.\nFind $X''$ such that $|X''| = k$ and $|f(X'')| = m$\nIf it was P then so would set cover: fix $m = |Y|$ and iterate over all $k \\in {1, \\dots, |X|}$ to find a minimum.\nLet's call this problem $\\text{exact}(G, k, m)$ and let's call your problem $\\text{largest}(G)$.\nLet $G(X, Y, E)$ be any bipartite graph. Let $G^1$ be a graph with one additional vertex in $X$, not connected to anything. Let ${_1}G$ be a graph where for every vertex of $X$, a new vertex is added to $Y$ and the two are connected. Let ${^1}G$ be a graph where for every vertex of $Y$, a new vertex is added to $X$ and the two are connected. Let ${_k^l}G^i = ({_k}({^l}G))^i$ be these transformations applied repeatedly. Note the order.\n$G^i$ will be used to artificially raise $|X^+|$ and therefore $|f(X^+)|$.", "433" ], [ "${_k}G$ will be used to weight down vertices $v$, so we can control whether $v \\in X^+$ even if $f(v) \\subset f(X^+)$ in $G$. ${^l}G$ will be used to prioritize larger $|f(X^+)|$.\nSay $X^+ = \\text{largest}(G^i)$. This implies that $\\text{exact}(G, |X^+|-i, |f(X^+)|)$, because you know that the $i$ new vertices in $X$ will be used and thus $|X^+|$ old vertices have a neighborhood of $|f(X^+)|$ old vertices. Similarly $X^+ = \\text{largest}({_k}G)$ implies $\\text{exact}(G, |X^+|, |f(X^+)|-k|X^+|)$.\nTo find $\\text{exact}(G, k, m)$, let $X^+_i = \\text{largest}({_M^i}G^{(mi+k)M+(m-k)})$ for sufficiently large $M$ (say, $M = |X|+|Y|$).\n* If $|X^+_0| < kM + (m-k) + k$ then $\\text{exact}(G, k, m)$ is false.\n* If $|f(X^+_i)| = (mi+k)M+m$ then $\\text{exact}(G, k, m)$ is true. Note that if $\\text{exact}(G, k+ix, m-x)$, then $|f(X^+_i)|$ could also have the value $(mi+k)M+m-x$.\n* Raise $i$ until $\\forall x>0, \\neg \\text{exact}(G, k+ix, m-x)$ (you can jump directly to $i=|X|$). Then $|f(X^+_i)| = (mi+k)M+m$ if and only if $\\text{exact}(G, k, m)$.", "433" ], [ "This problem can be solved in polynomial time by a product construction. Construct the graph $G^\\prime$ as follows:\n* The vertices of $G^\\prime$ are $(V \\times M) \\cup {#}$, i.e. all pairs of a vertex of $G$ and a state of $M$, together with an extra vertex identified by the arbitrary symbol $#$.\n* For each edge in $e \\in E$ from $v_1$ to $v_2$, add an edge in $G^\\prime$ from $(v_1, m_1)$ to $(v_2, m_2)$ with weight $w(e)$ if and only if there is an edge in $M$ from $m_1$ to $m_2$ that is labeled $\\ell(e)$.\n* For each accepting state $m$ in $M$, add an edge in $G^\\prime$ from $(t, m)$ to $#$ with weight 0.\nThen the shortest path in $G^\\prime$ from $(s, m_0)$ to $#$ (where $m_0$ is the initial state of $M$) gives the shortest path in $G$ from $s$ to $t$ matching $L(M)$.", "433" ], [ "There cannot be a negative cycle in $G^\\prime$, since dropping the $m$ states from the vertex labels would give a negative cycle in $G$, which we are assuming does not exist.\nThis also answers the question if $M$ is a DFA or regular expression instead of an NFA, since these can be converted to an equivalent NFA in polynomial time. We can also directly handle NFAs with $\\varepsilon$-transitions: if $M$ contains an $\\varepsilon$-transition from $m_1$ to $m_2$, add an edge in $G^\\prime$ with weight 0 from $(v, m_1)$ to $(v, m_2)$ for each $v \\in V$.\nFor fixed $M$, the product graph $G^\\prime$ has only linearly more vertices and edges than the original graph $G$. This means that any fixed problem of the form \"find the shortest path that visits edges in such-and-such order\", such as the problems linked in the question, can be solved just as fast as the ordinary shortest path problem asymptotically.\nAs an implementation detail, note that there is no need to actually write down the whole product graph in memory. The vertices and edges can be generated dynamically while running the shortest path algorithm, which allows unused vertices to be skipped entirely.", "433" ], [ "$k$-Opt TSP Local Search is exact when $k = |V| - 1$\nI've been self-studying the book Algorithms by <PERSON>, <PERSON> and <PERSON>. I am having a hard time with a question about local search involving the traveling salesman problem (TSP).\nWe'll say a local search algorithm is exact if it always returns a globally optimal solution.\nConsider a local search algorithm for TSP that uses neighborhoods defined by $k$-change: two tours $T_0$ and $T_1$ are neighbors if one can delete $j \\leqslant k$ edges from $T_0$ and add back another $j$ edges to obtain $T_1$. This is known as the $k$-Opt algorithm.\nIt's easy to see and the book itself discusses how for low values of $k$ (relative to the number $n$ of vertices), $k$-Opt may get stuck on locally optimal solutions that are not globally optimal. In other words, $k$-Opt is not exact for these values of $k$.\nIn fact, in a previous question, it was shown $k$-Opt is not exact for $k = \\lceil n/2 \\rceil$. Now, I'd like to show that\n$k$-Opt is exact for $k = n-1$.\nI have a near solution which I describe below.\nGiven an optimal tour $T^$ , if some tour $T$ shares at least one edge with $T^$, then $(n-1)$-change can take $T$ directly to $T^*$.\nFor $n\\geqslant 5$, we can have a tour $T_0$ which shares no edge with a given optimal tour $T^$.\nSuppose there were intermediate tour $T_1$ that uses only edges from $T_0$ and $T^$, and at least one edge from each.\nIt's not too hard to see that in this situation, $T_1$ will have at least two edges from each of $T_0$ and $T^*$, though I couldn't make much use of this.\nNow, for such a tour $T_1$, there are three cases:\n* $\\text{cost}(T_1) < \\text{cost}(T_0)$.\nThis is the easiest. Either $\\text{cost}(T_1) = \\text{cost}(T^)$ and we're done, or else in another move we can take $T_1$ to $T^$ (since they now share at least one edge).\n* $\\text{cost}(T_1) = \\text{cost}(T_0)$\nIn this case, $\\text{cost}(T_1\\setminus T_0) = \\text{cost}(T_0\\setminus T_1)$.\nBy construction $T_1\\setminus T_0$ is a subset of the edges in $T^$, so we can remove those edges in $T^$ and replace them with $T_0\\setminus T_1$.", "180" ], [ "This replacement has no cost change, and hence leads to another globally optimal solution $T'$.\n$T'$ is then a globally optimal solution that shares at least one edge with $T_0$, and is hence reachable from $T_0$ in a single move.\n* $\\text{cost}(T_1) > \\text{cost}(T_0)$\nWe show this case is not possible. If it were, then $\\text{cost}(T_1\\setminus T_0) > \\text{cost}(T_0\\setminus T_1)$.\nLike above, we could then remove the edges $T_1\\setminus T_0$ from $T^$ and replace them with $T_0\\setminus T_1$. This time however, $\\text{cost}(T^)$ would decrease, contradicting the global optimality of $T^*$.\nThe only missing piece would be to show the existence of $T_1$. I could solve examples drawn by hand but have had trouble showing this formally.\nI would also like to add that the the existence of $T_1$ must be guaranteed (under the assumption that $(n-1)$-Opt is exact). Indeed, we can handcraft this scenario as follows.\nConsider a complete graph $G = (V, E)$ with $n = |V| ⩾ 5$. Let $T^$ and $T_0$ be edge-disjoint tours in $G$.", "433" ], [ "Packing sets to maximize overlap\nWe are given a set of $m$ elements ${e_1,...,e_m}$ that form our universe $\\mathcal{U}$. Each element of our universe is further associated with a positive weight $w(e_j)$ with $j\\in {1,...m}$. We are further given a collection $S={S_1,...S_n}$ of subsets of $\\mathcal{U}$ whose union equals the universe. The intersection of any two sets in $S$ may be non-empty (i.e. subsets may overlap with each other).\nFurthermore,\n1) we are given an infinite number of configurations; each configuration can host up to $k$ subsets from $S$. There is no cost for using a configuration.\n2) When assigning 2 or more subsets to one configuration and there is an overlap between the sets (i.e.", "690" ], [ "an element is part of more than one set) we pay the weight of that element only once. Obviously, there can be no overlap between subsets when considering different configurations.\nObjective:\nwe want to assign each subset of $S$ to exactly one configuration in such a way that the weighted sum of the elements over all configurations is minimized. Consider the following example:\n$\\mathcal{U}={a,b,c,d,e,f,g}$,\n$w(a)=2$\n$w(b)=2$\n$w(c)=3$\n$w(d)=4$\n$w(e)=1$\n$w(f)=2$\n$w(g)=2$\n$S={S_1, S_2, S_3},$\n$S_1={a,b,c}, S_2={c,d,e}, S_2={e,f,g}$\n$k=2$\nIn this case, since $k<|S|$, it is obvious that more than one configurations are needed. Moreover, $S_1$ and $S_2$ should be packed together in the same configuration because of their heavy overlap ($S_1 \\cap S_2$ gives the biggest overlap in our example - we pay 3 less cost units). So, the total cost of such an assignment is 12+5=17 and 2 configurations are needed.\nAny ideas on how to prove that the problem is indeed intractable? Any ideas on how to calculate a good bound on the number of configurations that are needed?\nThe unweighted version (when the weights of the elements are all 1) is also very interesting to me. However, I did not manage to find something so far in the literature also for this problem.\nThank you!", "690" ] ]

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[ [ "Packing sets to maximize overlap\nWe are given a set of $m$ elements ${e_1,...,e_m}$ that form our universe $\\mathcal{U}$. Each element of our universe is further associated with a positive weight $w(e_j)$ with $j\\in {1,...m}$. We are further given a collection $S={S_1,...S_n}$ of subsets of $\\mathcal{U}$ whose union equals the universe. The intersection of any two sets in $S$ may be non-empty (i.e. subsets may overlap with each other).\nFurthermore,\n1) we are given an infinite number of configurations; each configuration can host up to $k$ subsets from $S$. There is no cost for using a configuration.\n2) When assigning 2 or more subsets to one configuration and there is an overlap between the sets (i.e.", "690" ], [ "an element is part of more than one set) we pay the weight of that element only once. Obviously, there can be no overlap between subsets when considering different configurations.\nObjective:\nwe want to assign each subset of $S$ to exactly one configuration in such a way that the weighted sum of the elements over all configurations is minimized. Consider the following example:\n$\\mathcal{U}={a,b,c,d,e,f,g}$,\n$w(a)=2$\n$w(b)=2$\n$w(c)=3$\n$w(d)=4$\n$w(e)=1$\n$w(f)=2$\n$w(g)=2$\n$S={S_1, S_2, S_3},$\n$S_1={a,b,c}, S_2={c,d,e}, S_2={e,f,g}$\n$k=2$\nIn this case, since $k<|S|$, it is obvious that more than one configurations are needed. Moreover, $S_1$ and $S_2$ should be packed together in the same configuration because of their heavy overlap ($S_1 \\cap S_2$ gives the biggest overlap in our example - we pay 3 less cost units). So, the total cost of such an assignment is 12+5=17 and 2 configurations are needed.\nAny ideas on how to prove that the problem is indeed intractable? Any ideas on how to calculate a good bound on the number of configurations that are needed?\nThe unweighted version (when the weights of the elements are all 1) is also very interesting to me. However, I did not manage to find something so far in the literature also for this problem.\nThank you!", "690" ], [ "Optimizing coin splitting - Is this algorithm as fast as I think?\nIn a recent exam, I've been asked to solve the following problem:\nThe problem\nTwo players play the following game: Given a sequence of coin values $v_1,\\ldots,v_n (n \\vert 2)$ the players take turns in taking one coin from either \"end\" of the sequence. The value of that coin is added to their score.\nPlayer 1 always starts. What is the maximum score that Player 1 can reach if Player 2 plays optimally (always minimizing their potential score)? What is the time-complexity of your algorithm? Prove your result.\nExample:\nGiven the coin sequence $1,1,3,1,1,2$ one of the best playing sequence for player 1 is (scores denoted as the second tuple):\n$$(\\lbrack 1,1,3,1,1\\rbrack,(2,0)) \\rightarrow (\\lbrack 1,1,3,1\\rbrack,(2,1)) \\rightarrow (\\lbrack 1,3,1\\rbrack,(3,1)) \\rightarrow (\\lbrack 3,1\\rbrack, (3,2)) \\rightarrow (\\lbrack 1 \\rbrack, (6,2)) \\rightarrow (6,3)$$\nThe best score player 1 can reach is 6.\nMy solution\nI'm just going to roughly outline my proof here, the formal correctness is not the point of this question. I'm more interested in the correctness of my asserted upper bound of complexity.\nFor the following I will use tuples to denote ranges of values.", "180" ], [ "$(i,j)$ specifies the value range $v_i,\\ldots,v_j$.\nWe iteratively create a DAG $G = (V, E, \\gamma)$ as follows:\nCreate a vertex $v$ named $(1,n)$. Create or refer to the previously created vertices $v_1, v_2, v_3$, named $(2,n-1), (3,n), (1,n-2)$ respectively.\nCreate the edges $e_1 = (v,v_1), \\gamma(e_1) = v_1$ and $e_2 = (v,v_2), \\gamma(e_2) = max\\lbrace v_1, v_n \\rbrace$ and $e_3 = (v,v_3), \\gamma(e_3) = v_n$. Iterate through the vertices $v_{\\lbrace 1,2,3\\rbrace}$ using a queue or similar to repeat the process until the sequence of coins denoted by the $v$ we iterate over is empty.\nThe number of edges in the created graph is bounded as follows: $\\lvert E \\rvert \\leq 3\\lvert V \\rvert$.\nThe number of vertices is denoted by the following sum: $1 + \\sum_{i=0}^{\\frac{n}{2}} 2i + 1 \\leq n^2$\nWe can determine the maximum score for player 1 by \"backpropagating\" the edge weights through the graph, which takes $\\lvert V \\rvert * \\lvert E \\rvert$ steps.\nThis makes the overall algorithm asymptotically require $\\Theta(n^2)$ steps\nThe problem I have with my answer is the upper bound for the number of vertices. I just pull that number out of thin air and my gut-feeling tells me that it is correct, but I might just be completely wrong.\nAssuming that this is indeed a correct way to calculate the answer to the question, is my time-complexity argumentation sound?", "172" ], [ "What is the name of this logistic variant of TSP?\nI have a logistic problem that can be seen as a variant of $\\text{TSP}$. It is so natural, I'm sure it has been studied in Operations research or something similar. Here's one way of looking at the problem.\nI have $P$ warehouses on the Cartesian plane. There's a path from a warehouse to every other warehouse and the distance metric used is the Euclidean distance. In addition, there are $n$ different items. Each item $1 \\leq i \\leq n$ can be present in any number of warehouses. We have a collector and we are given a starting point $s$ for it, say the origin $(0,0)$. The collector is given an order, so a list of items. Here, we can assume that the list only contains distinct items and only one of each. We must determine the shortest tour starting at $s$ visiting some number of warehouses so that the we pick up every item on the order.\nHere's a visualization of a randomly generated instance with $P = 35$. Warehouses are represented with circles.", "180" ], [ "Red ones contain item $1$, blue ones item $2$ and green ones item $3$. Given some starting point $s$ and the order ($1,2,3$), we must pick one red, one blue and one green warehouse so the order can be completed. By accident, there are no multi-colored warehouses in this example so they all contain exactly one item. This particular instance is a case of set-TSP.\nI can show that the problem is indeed $\\mathcal{NP}$-hard. Consider an instance where each item $i$ is located in a different warehouse $P_i$. The order is such that it contains every item. Now we must visit every warehouse $P_i$ and find the shortest tour doing so. This is equivalent of solving an instance of $\\text{TSP}$.\nBeing so obviously useful at least in the context of logistic, routing and planning, I'm sure this has been studied before. I have two questions:\n1. What is the name of the problem?\n2. How well can one hope to approximate the problem (assuming $\\mathcal{P} \\neq \\mathcal{NP}$)?\nI'm quite happy with the name and/or reference(s) to the problem. Maybe the answer to the second point follows easily or I can find out that myself.", "835" ], [ "Sum of size of distinct set of descendants $d$ distance from a node $u$, over all $u$ and $d$ is $\\mathcal{O}(n\\sqrt{n})$\nLet's consider a rooted tree $T$ of $n$ nodes. For any node $u$ of the tree, define $L(u,d)$ to be the list of descendants of $u$ that are distance $d$ away from $u$. Let $|L(u,d)|$ denote the number of nodes that are present in the list $L(u,d)$.\nProve that the sum of $|L(u,d)|$ over all distinct lists $L(u,d)$ is bounded by $\\mathcal{O}(n\\sqrt{n})$.\nMy work\nConsider all $L(u,d)$ such that the left most node on the level $Level(u) + d$ is some node $v$.", "743" ], [ "The pairs $u, d$ for all such $L(u,d)$ must be distinct and the sum of all $d_i$ will correspond to the number of nodes $x$ in the tree with $Level(x) \\le Level(u) + d$.\nThis is because if some sequence of nodes $v_1, v_2, \\dots v_k$ corresponds to the descendants of some node $u$ at a distance $d$ and the sequence of nodes $v_1, v_2, \\dots v_{k'}$ where $k' > k$ corresponds to the descendants of some node $u'$ at a distance $d+1$, then there must also exist a node $u''$ such that $L(u'', d) = v_{k+1}, v_{k+2}, \\dots v_{k'}$. This would also mean that $u''$ is not in the subtree of $u$ and thus there are at least $d$ distinct nodes in the subtree of $u''$ upto a distance $d$ from $u''$.\nIf the distinct distances are $d_1, d_2, \\dots d_k$ then, $n \\ge \\sum_{i}d_i \\ge \\sum_{i=1}^{k}i \\ge \\frac{k(k+1)}{2}$. =\n$\\implies k \\le \\sqrt{n}$\nAfter this I tried to show that there can be only $\\mathcal{O}(\\sqrt{n})$ distinct lists $L(u,d)$ so that I can then trivially obtain the upper-boud of $n\\sqrt{n}$ but I could not make any more useful observations.\nThis link claims that such an upper bound does exist but has not provided the proof.\nAny ideas how we might proceed to prove this?", "532" ], [ "Sample a set of N numbers without replacement, each element taken from N different weighted sets\nHere's my problem: I have $N$ sets of integers $S_i$ where $|S_i| = n_i \\forall i \\in [1,N]$ each with non-uniform weights $W_i = {w_{i,1}, ..., w_{i,n_i}}$ such that $\\sum_{j}{w_{i,j}} = 1$. I want to sample $m$ unique lists $P_{k \\in [1,m]} = (p_{k,1}, ...,p_{k,i}, ...,p_{k,N})$ of $N$ integers (including duplicates, and ordering matters), with each element $p_{k,i} \\in S_i$.\nThe naive implementation I use as a proof of concept to generate a new unique list $P_k$: I pick an element from $S_1$ at random according to the weights $W_1$, then I pick an element from $S_2$ with weights $W_2$, etc... until I have $N$ elements to create a candidate list. If this list is not unique among exiting lists, I discard it and start again at the top, otherwise it becomes the list $P_k$.", "690" ], [ "This is repeated until I get $m$ unique lists.\nAlthough it works and gives me the correct result, this is very inefficient as I get more and more duplicate sets as $m$ increases, and as the weights $w_i$ diverge from a uniform distribution.\nHere's an example with disjoint sets: $N=3, n_1=4, n_2=3, n_3=5$ $$ S_1 = {1, 2, 3, 4}; S_2 = {11, 12, 13}; S_3 = {21, 22, 23, 24, 25}; $$ With $m=3$, a possible sampling would be: $$ P_1=(1, 11, 21), P_2=(1, 12, 24), P_3=(3, 12, 22) $$\nAll the sampling algorithms I have found either assume uniform distribution, or require \"flattening\" my problem from $N$ sets to one set of all possible combinations (and calculating the corresponding weights). Although the computation of the weight for a specific combination is trivial, it is not feasible for the size and number of sets I'm working with: $2 \\leq N \\leq 20$ and $2 \\leq n_i \\leq 50$. Typically $1 \\leq m \\leq 1000$ and $m \\leq \\prod_{i \\in [1,N]}{n_i}$.\nDoes anyone has an idea to replace my current naive solution? I am looking for an algorithm that would allow me to make that sampling without replacement a. directly from $S_i$ and $W_i$, or b. a 1D weighted sampling algorithm that does not require pre-computing all possible combinations and corresponding weights.", "690" ], [ "tl;dr I wrote some solution but realized it is not perfect. Since I didn't want all this typing to go waste I figured I might post my observations here rather than splitting them in the comments.\nI think that the problem can be solved for any arbitrary $s,t$ and $x$ in $\\mathcal{O}(V+ E)$. In fact we can extend the problem to answer $Q$ queries of the form $(s,t,x)$ with $\\mathcal{O}(V+E)$ pre processing and $\\mathcal{O}(1)$ per query. I am having trouble completing step 6, but I am pretty sure that it can be done. Someone in the comments may know.\n1. Find all strongly connected components (scc) of the graph using Kosarjau's or <PERSON> algorithm. This step will take $\\mathcal{O}(V+E)$ time.\n2. Using a hash table, you can check if two nodes belong to the same stongly connected component in $\\mathcal{O}(1)$ time.\n3. If two nodes $u$ and $v$ belong to the same strongly connected component, then there exists paths both from $u$ to $v$ and $v$ to $u$.\n4.", "835" ], [ "Now what remains to be checked is if two nodes $u$ and $v$ do not belong to the same strongly connected component, does there still exist a path from $u$ to $v$.\n5. We will modify the given graph $G$ to a new graph $G'$ which we shall call the strongly connected component graph or scc graph for short. In the scc graph, each node corresponds to one strongly connected component in the original graph i.e. we compress all nodes belonging to the same scc to a single node. It can be proven that the scc graph is a Directed Acyclic Graph (DAG for short).\n6. Now our task reduces to check if there exists a directed path between $u$ and $v$ in the DAG. Topological sort can give an ordering such that for any path from $u$ to $v$, $u$ will appear before $v$ in the ordering. Thus we can check if index of $u$ in the topologically sorted sequence of vertices is less than that of $v$ in $\\mathcal{O}(1)$ but this method also gives false positives and this is where I am stuck.\n7. I feel that we can augment step 6 with some additional data to complete the algo. One method I was thinking of was to maintain some constant $K$ number of random topological sorts and if the inequality $index(u) < index(v)$ is true for all $K$ sequences then we can conclude with high probability that there is a path from $u$ to $v$.", "433" ], [ "Is there an efficient algorithm for finding a minimal common subset of pairwise distinct bits in a set of bit strings?\nI am working on an efficient mapping function represented as a directed graph. In essence, it is a sort of radix trie. A path must be formed from a bit string [string hereon] efficiently. To do this, I decided on looking for and using an algorithm that finds a continuous, common subset of bits at a particular offset and length from a set of strings. I will describe the general algorithm that I seek formally as follows:\nGiven: $$S := \\left{s_y | s_y = B_y \\right}$$ $$B_y := \\left{b_x | b_x\\in \\left{0,1\\right}\\right}$$ and $$s_{y,x} = B_y[x]$$ we seek to find a common subset $s_{1...|S|,p...q}$ such that $\\forall\\left{p, q \\right}\\in\\Bbb{N}$, $\\nexists \\left{p', q' \\right}\\in\\Bbb{N} \\text{ s.t. } |p' - q'| < |p - q|$.\nFor the general case, the common subsets permit to find $s_{1...|S|, p_k...q_k}$. Some analysis shows that $\\lceil\\log_2(|S|)\\rceil \\leq |p - q| \\leq \\lfloor\\log_2(s_{largest} \\lor 1)\\rfloor + 1$ where $s_{largest}$ is the string whose magnitude $|B_y|$ is greater than all other $|B_y|$ in $S$.\nAs an example algorithm for demonstration, suppose we have the following four strings, each four elements in length: $$ s_1 = \\left{1, 0, 1, 1\\right}\\ s_2 = \\left{0, 1, 0, 1\\right}\\ s_3 = \\left{1, 1, 0, 1\\right}\\ s_4 = \\left{1, 1, 1, 1\\right} $$\nWe define a column thusly: $$c_{x} = s_{1...|S|,x}|x\\in\\Bbb{N}$$ with $c_1$ being the first column, right to left order convention, and $c_{|S|}$ being the last.\n1. $p_c\\leftarrow 1$. $q_c\\leftarrow 0$. Column offset and (horizontal) width variables, respectively.\n2. We see that the column $c_1$ is all ones, so we decide to skip it and go to $c_2$.", "180" ], [ "Increment $p_c$ and $q_c$.\n3. $c_2$ varies, but there are only two distinct values of the four in $c_{1..2}$ read by rows. Increment $q_c$.\n4. The column $c_3$ varies, and we see that there are three distinct values when read by rows, not four, so we move on to the next column. Increment $q_c$.\n5. $c_4$ varies. Increment $q_c$.\n6. We observe that all the columns we have, $c_{1...q_c}$, are now pairwise distinct when read by rows. Record $p_c$ and $q_c$. Terminate algorithm.\n(Proof: the values read by rows interpreted as binary integers and converted to base ten read as $[5, 2, 6, 7]$.)\nIt's quite obvious that there is a deterministic algorithm hidden somewhere in this process using some combination of Hamming weight and XOR: for any given column, the Hamming weight of the XOR of any two columns $c_a$ and $c_b$ tells us how many unique values are represented by the common subsequence given by offset $p$ and length $q$, but I haven't yet figured out how to generalize this just to create a deterministic algorithm for all columns.\nIf this algorithm already exists, I do not know what it is called. For my particular implementation it would be ideal if the whole set did not have to be analyzed each time a key is added to our map, but that previous information from previous computations can be used to quickly analyze a new key and determine whether or not we need to extend the sequence again, or can keep the existing index and sequence length.\nWhat already exists that can be implemented? If not already existing, are there any ideas on how best to proceed with an optimal algorithm as described here?", "603" ], [ "Imagine that we have an array $A$ of size $n$. Mergesort splits this array into two equal halves and sorts them individually. So in context of the paragraph you have provided, each node corresponds to some chunk of the original array that we want to sort. We divide a node $A[L,R]$ to two nodes $A[L,M]$ and $A[M+1,R]$ with $M = \\frac{L+R}{2}$\nThe splitting of a node $A[L,R]$ into two nodes takes $R-L+1$ time and then merging the two child nodes $A[L,M]$ and $A[M+1,R]$ again takes $A[R-L+1]$ time.", "743" ], [ "Thus for every node, the number of operations the algorithm performs is equal to twice the size of the array corresponding to that node.\nThus we have that on any particular level if we have an array of size $k$, splitting and merging of the array can be done in $k + 2\\times \\frac{k}{2} = 2k$ operations.\nNow note that we keep splitting the array till we have arrays of size $1$ since we can't split them further.\nDraw a binary tree with the root node corresponding to the array $A[1,N]$ and with each node having two children corresponding to its left and right halves and recursively draw the structure for each child till we have arrays of size $1$. Denote each node by the size of the array that it corresponds to. We will get something that looks like this\n(Taken from Khan Academy)\nThis is the recursion tree for merge sort.\nThe computation time spent by the algorithm on each of these nodes is simply two times the size of the array the node corresponds to. Therefore the total running time $S$ of mergesort is just the sum of all the sizes of the arrays that each node in the tree corresponds to i.e. $$S = 2 \\sum_{i=0}^k 2^i\\frac{n}{2^i}$$\n(How did we get this sum? There are $2^i$ nodes of size $\\frac{n}{2^i}$ in the tree and it takes $2k$ time to finish computation on an array of size $k$)\nObserve that when $i=k$, $\\frac{n}{2^k} = 1 \\implies n = 2^k \\implies k = \\lceil{\\log n}\\rceil$ Thus $S$ reduces to $$2 \\sum_{i=0}^{\\lceil{\\log n}\\rceil} n = 2n\\lceil{\\log n}\\rceil = \\mathcal{O}(n\\log n)$$", "743" ] ]

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[ [ "Cat litterbox situation\nCat rehoming issues\nIn August I moved into a home that had two other cats, a male (Zazu) and a female (<PERSON>) cat. The male cat does not like to be touched and came from a hoarding house where he was not treated well. He had been living there since January.\nI moved in with my male cat (<PERSON>, about 5 y.o) in August. <PERSON> had been raised with another male cat about 10 years older than him, and his mom. I moved across the United States two years ago with <PERSON> and his mom. We moved together two more times, and I eventually got a third cat (male kitten) with my now ex husband. I was only able to bring <PERSON> with me and had to give up the other two.\nI have never had any spraying or litterbox issues with any of my cats, especially <PERSON>. We tried to slowly introduce the cats, but it was difficult since I’m allergic to them and he couldn’t be in my room. <PERSON> got used to <PERSON> and now they love each other, but <PERSON> HATES <PERSON>, and now doesn’t get along with <PERSON> either. <PERSON> will get in <PERSON>’s space, not necessarily looking for a fight, and <PERSON> with hiss and growl at him.", "311" ], [ "It got to the point though that <PERSON> had <PERSON> cornered downstairs and <PERSON> was forced to use the restroom in that corner.\nAlso, during this time, I split the price on an automatic litter box that my previous three cats had used before with no issue. <PERSON> refused to use it or his own litter box, so we had to move it away from his. The litter box wouldn’t work where we moved it, so we eventually moved it back (especially because <PERSON> wouldn’t use it when <PERSON>’s litterbox was moved upstairs).\nWe finally just decided to keep <PERSON> upstairs in my roommates room when I caught <PERSON> peeing upstairs, and had cleaned up pee several times downstairs. I have caught Catan spraying downstairs as well.\nEverything was going better and I continued to use a no spray bottle downstairs. Until my roommate came home and noticed a really bad smell, and my roommate walked in on him peeing where the old litterbox was. We found out through the automatic litter that <PERSON> had stopped using his litterbox a week ago, even though after we moved it back he was still using it for awhile (so I’m not sure what changed).\nMy roommate says that the cement will have to be treated (carpet floors) and that I need to find a solution before the next roommate comes (one of our roommates is moving out). I have had <PERSON> since he was born, and he’s one of my close connections from my home on the other side of the country. I also really like where I live and am not ready to move out. We have feliway spray downstairs and it hasn’t done anything. I’m trying to be vigilant about the no spray spray, but idk if it’ll stop him from going #2. I’m desperate to keep him, but I also know there are not a lot of places to live at the price I pay, and my money situation is not the best.", "311" ], [ "Cat peeing next to litter box and in the house\nI have a 4 year old cat who has brain damage from seizures when he was young. He’s been perfectly fine with peeing in the litter box for years, even when we moved houses. Up until a couple months ago that it. He started peeing outside my bathroom door enough that we have water damage by the base boards from shampooing it and just started peeing next to the litter box as well.", "311" ], [ "It’s really frustrating and no one else in my house wants to try to help me fix it, they just keep saying we should put him down.\nWe have two cats and one litter box (I’ve tried to get another but my parents won’t budge on only having one). He isn’t showing any signs of urinary issues outside of this. He even uses the litter box often and if we catch him trying to pee where he shouldn’t, he runs to his litter box to go. I’ve taken the covering off his litter box in hopes that it will help but I don’t know what else to do. I’m worried my dads gonna put him down when I go away for a week if I can’t find a way to help him.\nAny advice?", "311" ], [ "Are cats more affectionate when recovering from something?\nOr maybe its because he is an outdoor cat. Anyway, I've been feeding and gaining the trust of 4 feral cats for over a year, since they were kittens. Prior to this, I had no care experience with cats, as all my pets have been dogs. I was able to gain their trust enough to pet all of them and pick up 3 of them (the other is a VERY flighty and sassy calico, so I rarely try to pick her up).\nThe other day one of them had half of his tail entirely degloved down to the bone. We don't know from what, but luckily the vets said it was a clean wound and not a bunch of torn ligaments.", "961" ], [ "They amputated it and told us to keep him in doors, which we were hesitant about as our home is not cat proof, but decided to keep him in a bathroom as I've seen people on YT do with newly adopted cats.\nHe usually is not that affectionate. Yes, he will let us pet him and likes his neck scratched but he doesn't seek us out that often. But as of now (its only been 2 or 3 days), he is on constant purr mode when I enter the room, pacing back and forth to get me to scratch his butt or neck. He also rolls over on the floor, like his brother (the most affectionate of them) does when telling us \"oh get this spot here\" (he is very spoiled lmao). This morning he climbed into my lap and laid down to go to sleep. When I tried with any of them before to put them in my lap, they'd immediately jump down.\nSo is this normal?", "311" ], [ "help, my roommate's cat keeps pissing on my bed\nI have lived with my roommate and her cat for over a year now. Last year, [2b1b] my roommate was in a single and her cat spent most of his time there. I shared a room with a different roommate and sometimes the cat would come in and pee on her bed (she had the lower bunk bed) but we fixed that problem by locking the door. Around the same time, he got diagnosed with a UTI as he was peeing some blood. Now, I live with the same roommate and her cat, we're in a 1 bedroom apartment sharing a room. We figured he wouldn't be pissing around as he's been eating his UTI cat food and has a clean litter box. Ever since we moved in May, he's been pissing on the walls (no blood though) and I've tried to clean it up (we don't have an enzyme spray).", "311" ], [ "Until maybe around 2 months ago, he started pissing on my bed and I've washed my sheets every time. Now, our plan is to buy an enzyme spray and keep washing my sheets.\nFor context, I'm gone almost every weekend as I go home to my boyfriend's. Lately, I've been coming back to my apartment to find my bed smelling. I figure that he likes to piss on it when I'm gone. Maybe it's because my boyfriend has cats? But that wouldn't explain why he pees when I'm gone.\nThe cat is fixed and around 3 years old. He has a food schedule & a clean litter box. He's the only cat in our apartment. The little box is in the living room and the litter type hasn't been changed since his UTI incident.\nWhat should I do? If he's known me for a while, why is he still pissing on my bed?", "311" ], [ "Hypersensitive cat help\nShould we get a 4th cat?\nWe have 3 cats and recently found a very friendly stray kitten (no chip, still waiting to hear back from posting to Facebook). 2 of our cats are male that get along relatively well, besides some rough playing every once in a while. The third is a declawed (previous owners fault) hypersensitive female and much smaller than the other 2, so she has to to be kept in our bedroom to avoid them picking on her.", "311" ], [ "We have neighbors who are interested in adopting a cat. We introduced them to the stray kitten we found and they seemed to really like her, but we were also wondering about introducing the hypersensitive female to them, since it seems like she would be happier as the only cat in the house. The only issue with that is that she takes a long time to warm up to people and I wouldn't want to \"burden\" my neighbors with a cat that wouldn't even want to be around them for 5+ months.", "679" ], [ "Putting a cat up for adoption\nI have 4 cats, 2 bonded, the others over time. The bonded ones I don’t believe are truly bonded, they don’t seem to care about each other at all.", "176" ], [ "One of them is very shy, terrified of any movement and of the other cats. She only comes out to eat and use the litter box and on occasion she wants to be petted but acts like she is terrified of me and the other cats are all times. Is it wrong for me to want to regime her in hopes that she would do better in a single quiet household? I’ve had her 1.5 years and she is 2.5 years old.", "679" ], [ "How soon is too soon to get another cat after your cat dies?\nMy beloved cat who was only 3 died suddenly (within a minute) traumatically due to an underlying heart condition. This happened a month ago. This was very shocking as he showed virtually no clinical signs. I was absolutely devastated. I loved that cat more than I have loved any animal. My boyfriend feels the same way. This happened a month ago. I cry intermittently about it. I have a memorial for him in my apartment. I will never forget him.\nHowever, I have always had animals in my life. They are very important to me.", "961" ], [ "I’m a vet student in an extremely rigorous and demanding program that chips away at my mental health. I also have mental health problems. Having an animal relieves just a little bit of that pain. I am feeling like I would like another cat. But I am worried. My last cat I loved so so much. He was aggressively affectionate, goofy, and never ever caused problems (no peeing outside litter box, no biting, etc.) im worried about another cat not being this way. I’m also worried it is much too soon to get another cat. My kitty died a month ago. I feel like I’m not honoring him by replacing him. I also feel like it isn’t fair to the other cat I’m bringing in to be a “replacement.” Also people may judge if I just replace my beloved cat.\nI guess what im asking is - when is it too soon to get another cat?", "961" ], [ "Should we get a 4th cat?\nWe have 3 cats and recently found a very friendly stray kitten (no chip, still waiting to hear back from posting to Facebook). 2 of our cats are male that get along relatively well, besides some rough playing every once in a while. The third is a declawed (previous owners fault) hypersensitive female and much smaller than the other 2, so she has to to be kept in our bedroom to avoid them picking on her.", "311" ], [ "We have neighbors who are interested in adopting a cat. We introduced them to the stray kitten we found and they seemed to really like her, but we were also wondering about introducing the hypersensitive female to them, since it seems like she would be happier as the only cat in the house. The only issue with that is that she takes a long time to warm up to people and I wouldn't want to \"burden\" my neighbors with a cat that wouldn't even want to be around them for 5+ months.", "679" ] ]

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[ [ "Intro:\nI've been a souls fan since Demon's Souls, having backed the Dark Souls Board Game and played it extensively despite its numerous shortcomings. With CMON helming Bloodborne, and the first bits shown of it looking like a far more fleshed out game than its steamforged brother, it was a no brainer that I go all in backing this game.\nHaving now received it, painted it, and dove into at least 10 campaigns, around 9 of which saw the final boss falling at the end of it, I can safely say this is my favorite co-op board game. However that is not to say there aren't small quirks, as well as some truly baffling and embarrassingly poor elements that stick out like a sore thumb that I can't turn a blind eye to even if they weren't dealbreakers for me- This review will be a sectioned look at all that, with a summary at the end if you want to skip to that.\nGameplay:\nThis is going to be a fairly quick summary, boiling things down to their essence for those totally unfamiliar with the game, feel free to skip ahead if that isn't you.\nThe game is played with 1-4 players, each choosing a unique hunter, boasting a double sided trick weapon card featuring up to three different attacks as well as an ability on each side. Players use a deck of 12 cards to perform every action in the game, be it moving, attacking, or interacting. This deck of cards can be upgraded over the course of the campaign, primarily by killing enemies over the three standard chapters of a campaign.\nWhile the overall themes and gameplay of chapters vary wildly, they boil down to trying to complete the Hunt Objective, which is nearly always advanced by completing insight missions, which will be revealed upon finding certain tiles as you explore Yarnham, revealing tiles from a shuffled deck of tiles in a \"Betrayal at house on the hill\" type manner- With the needed tiles being somewhere in the deck in addition to a limited number of random ones.\nAs rounds pass and players die or dream, the \"Hunt Track\" ticks up, reseting all enemies every 4th tick, which also resets bosses HP as well as certain mini boss type enemies spawned by the campaign. When the final spot on the track is reached you have that one round to complete the hunt. Fail and the campaign is over and you'll have to tackle it again from scratch.\nShould you reach the end of the campaign, the final hunt mission is always a showdown with a boss, each which has two phases and unique attack decks- Bring them down and all thats left is to read the conclusion!\nContents/Value:\nThe base game comes packed with 4 hunters, 4 campaigns and their respective bosses, and 7 different enemies each which has 4 figures.", "386" ], [ "For the price and considering the quality of the figures this is quite good bang for your buck, especially since each campaign has replay value and the average campaign seems to take 6 or so hours, meaning you are looking at about 24 hours of unique play experience. However, the one glaring shortcoming is that there are only 4 hunters to play with, meaning in a four player game there will be no team composition variety, and your choices are very narrow.\nThus in terms of content and improving play quality the Blood Moon Box which adds a whopping 6 hunters and the Chalice Dungeon Expansion which adds 4, with both adding a slew of enemies you can include in certain campaigns, and the entire chalice dungeon game mode, I would recommend them even to first time players unless you are more focused on campaigns over everything else in which case the Forbidden Woods and Cainhurst offer two full campaigns plus one mini chapter each, as well as much welcome new tile sets.\nThen that just leaves the small box expansions which offer a single boss, two unique enemies, a jumbo sized tile, and a campaign which utilizes all of them. While I have enjoyed the majority of these, they objectively offer far less content than any of the other expansions by a fair margin and they aren't worth grabbing if you aren't a huge Bloodborne fan or already totally sold on the game.\nAddressing the Hunt Track:\nI wanted to dedicate a distinct section to this since there is so much controversy over it, and it seems to be a dealbreaker for some. The gut reaction a lot of people have is that the hunt track feels off, with high player count games feeling limited on how often you can dream. In addition, fighting a boss that resets its HP can feel like a flavor fail, which if it sequences into a loss ultimately, can feel bad.\nMy playgroups first game was 4 players, and we felt very similarly to that general consensus. However to anyone in the same boat I strongly recommend playing another campaign. A first playthrough is naturally going to have more deaths from mistakes/inexperience, people dreaming excessively, as well as simply missing rules.", "884" ], [ "I am not intending for this to be an exhaustive review, as the expansion does play identically to the base game in a lot of ways. I really just want to let players like myself, that bought Elder Sign on day 1 and were very disappointed, know that it's safe to come back now. The game is fixed.\nFirstly I would like to share my thoughts briefly on Elder Sign as well as Fantasy Flight's Arkham games line, as they will provide necessary context for the positives and negatives I state later. My first real game eight years ago was Arkham Horror and I have been madly in love with it ever since. I have since bought everything from said games line and play them religiously, although lately it has been easier to get my wife to play Eldritch Horror than Arkham. When Elder Sign was first announced, I thanked the Ancient Ones for this gift. Arkham Horror the dice game with a fraction of the set up and rules complexity? I followed the game diligently, pre-ordered and broke it out immediately after receiving it.\nElder Sign was and remains my single greatest gaming disappointment since I started collecting. The game lacked flavor, and more importantly it lacked soul. I had no connection with my character, much less what was happening to them, and even worse I effortlessly laid a beat down on every beastie and nightmare to come out of <PERSON>'s glorious head. After ~10/10 wins the game sat on my shelf until Unseen Force came out. Hope sprung anew. I also bought it immediately and rushed home to play it. It felt like artificially inserted difficulty, which was still pretty easy, and the game still lacked soul. And so back to the shelf it went.....till a couple of days ago.\nGates of Arkham is less an expansion than a complete reworking of a base game. You still get to keep your investigators and ancient ones (in fact you get more). You get to keep your items, spells, and allies too (more of those as well). It is worth noting you get to keep your Other World Adventures. The core gameplay is also identical. Your regular Adventures are gone though. Don't worry you won't miss them. What really changes is your approach to Adventures.", "304" ], [ "The Arkham Adventures deck which replaces the Adventures deck is filled with two sided tarot cards. The front of the cards will be very familiar to anyone familiar with Elder Sign. The backs however, tell you the specific area of Arkham the Adventure takes place in, occasionally a special action that can be taken when you travel there, sometimes a Midnight effect, and the difficulty of the Adventure. With the exception of three cards at setup all of these Adventure cards enter play face down, meaning you know nothing of what will happen when you go there besides the location's special action. This is the game changer. Pun.\nYou can no longer perfectly plan out all of your moves. You can't be low on sanity and simply avoid Adventures with a sanity cost or sanity fail penalties. A lot of Adventures also have Event icons on them which will require you to draw an Event card as you resolve the Adventure, so even face up Adventures will often contain surprises.\nOther Worlds also function entirely differently now. They enter play face down like everything else, but they also enter play with a gate token. Every Other World Adventure card in play is linked with an Arkham Adventure card in play of your choice. You are unable to interact with the linked Arkham Adventure card while the linked Other World is still in play. This creates some interesting decisions, as usually I keep the gates off of the face down At Midnight effect Adventures, so I can resolve them when I need to, and instead opt to put them on easy cards like the Asylum Adventures. Problem is that now when I want to go to the Asylum to use the special action to regain sanity I can't. It is also worth noting that when you \"close the gate\" by solving the Other World Adventure, you place a seal token on the linked Arkham Adventure card so another gate cannot appear on that card. Which sounds great, but if you ever need to place a gate but can't because all of the cards have gates or seals on them already, a gate burst happens which removes all the seals and advances doom. This is a decently thematic feature, but I thought it served best to add more complicated strategic decisions to the game.\nAnother new feature is the addition of faction affiliations. Through several game effects you can join the Sheldon Gang or the infamous Silver Twilight Lodge. These will provide you with assistance on certain Adventures, additional rewards, and occasionally surprise penalties. This feature actually created my favorite moment with the expansion thus far. I had joined the Silver Twilight already and was completing an Adventure when an Event card required me to place a monster on the card. This turned out to be a Gug, which would have made it unbeatable for me, but the Gug got placed on a monster space I could ignore as a member of the Silver Twilight.", "558" ], [ "Sun of York\nA game for 2 players designed by <PERSON>, and published by GMT Games\n“Now is the winter of our discontent\nMade glorious summer by this son of <PERSON>;\nAnd all the clouds that low'r'd upon our house\nIn the deep bosom of the ocean buried.”\n― Richard The Third Act 1, scene 1, 1–4\nIntroduction\nThere was a time where collectible card games were a hot new thing. Magic the Gathering is still the complete king, nay, emperor, of that domain, but it also spawned not a few card games the include either a deck building or deck construction mechanic.\nI played a few of them. I tried and actually liked from Columbia, but as the ACW isn't a subject of great interest to me, it kind of came and went.\nI've always liked the idea of a card based wargame without a map having the forces and terrain deployed on a table top, and then resolving the action through the play of cards. There are lots of games in this general category. There's two series by Columbia, the aforementioned Dixie and their . can arguably be included. despite not being a card game has a similar idea of an abstracted terrain.\nSo how does the idea of an abstracted card version of the War of the Roses translate into game play? Let's find out.\nComponents, Rules, and Gameplay\nThe game comes with two deck of cards, one for the Lancastrians and one for the Yorkists.\nIt also comes with some dice, counters for marking specific kinds of information, the rules, and a pair of player aid cards.\nThe cards are nicely done and the information on them is nice and clear and easy to read.\nThe game includes 20 (!!) scenarios and a set of campaign rules for those who want to keep track of their progress (or lack thereof). There is also a nice simple rule for playing random scenarios.\nThe players set themselves up with a virtual field of play that has a left and right flank, and in the centre are three rows battle zones split into left, centre, and right.\nThis lovely custom playing mat from <PERSON> showcases it nicely:\nEach turn is split into four phases: morale checks, combat, movement, and a discard phase. To win the game, you need to capture the centre rear space of your opponent, or both the left and right rear positions.\nThe initial deployment has each player take out the leader and terrain cards specified from the scenario and into the spaces they're assigned to, and then draws 16 more cards from their remaining deck to be deployed as they see fit.", "92" ], [ "You then flip it all face up and have at it.\nThe rules are relatively straightforward and everything you need to know about moving, engaging, fighting, and flanking are all easily found and explained in the rulebook.\nConclusions\nSun of York was a game I really wanted to like, but ultimately it left me unsatisfied. The fault likes not with the game itself, but rather my likes and desires in a game. As I stated in the introduction, I like the idea of an abstracted card game of a battle, but the reality is that I really want to have a map with units and terrain.\nThe deck contains a random mix of units, terrain, and leaders. There are some special event cards that you can play as well. This means that no two scenarios will be alike, yes, but also means that you can get completely ahistorical results.\nI may be overly picky on this point. I'm no scholar of the War of the Roses, and I'm not going to be able to point expertly at how the way combat is resolved in this game is a poor simulation of how archers behaved in this era. However, I don't get a strong sense of time and place with this game, and I could just as easily be playing a generic card game with soldiers and archers and leaders.\nIt's clear then that my preference for having a map and units to help me conceptualize what's going on in front of me. And that's no indictment of Sun of York, it just doesn't make it a game for me.\nIf you like card games like this, and you like this era, it's a solid entry in the genre.\nThank you for reading this latest installment of Roger's Reviews. I've been an avid board gamer all my life and a wargamer for over thirty years. I have a strong preference for well designed games that allow players to focus on trying to make good decisions.\nAmong my favorites I include , the , the , , , , , and\nYou can subscribe to my reviews at this geeklist: and I also encourage you to purchase this very stylish microbadge:", "993" ], [ "Moonbase Alpha\nA game for 2 players designed by <PERSON>\n\"If you're gonna die, you might as well die on Alpha.\" Commander <PERSON>, Space: 1999\nIntroduction\nI grew up in the era of Star Trek in syndicated re-runs, the real Star Trek, with <PERSON> and <PERSON> and company, Space:1999, the original and oh so cheesy Battlestar Galactica, and the occasional episode of <PERSON>. I also saw the original Star Wars on the big screen, and a host of other sci-fi too. These were also the halcyon days of Metagaming and their Microgame series, which produced such classic titles as Ogre and G.E.V.\nThose original Microgames are ones I remember with a lot of nostalgic fondness as they were all interesting but perhaps most importantly, fun! This brings me to good old Victory Point Games. I love them, I really do. They produce games that have interesting ideas or themes in them, and I love the core philosophy that they're willing to put out interesting games.\nMoonbase Alpha is a small wargame set in a not too distant alternate future pitting two mining companies, Mond Bergbau and Luna Mining Corp, against one another in the harsh environment of the moon. Of course, in space, nobody can hear you scream, so the disputes over lunar stake claims are easily resolved through the use of private security forces, but the media may report on your failings on the lunar surface and drive down your stock price.\nWait a minute! Your stock price? Yes! Your stock price! For what gives Moonbase Alpha its beautiful and clever twist that you, as the CEO of one of our two lunar mining conglomerates, care about your options package, and so the victory conditions of the game revolve around getting your stock price to €1.600 before your rival does.\nComponents\nI bought the Gold Banner edition of Moonbase Alpha which comes in a box, with a laser cut mounted board that comes in a five piece puzzle board showing the lunar surface divided into areas. The game is also available in ziploc format that comes with a paper map (included in the boxed edition). Either edition comes with the thick laser cut counters. Also included is a deck of technology cards, and in the boxed edition, four high quality medium sized six sided dice.\nI have always appreciated the games produced by VPG for their interesting topics and fun game play.", "92" ], [ "Although the production values once spoke to their print-on-demand nature (never forgetting that their raison d'être is to be a games idea incubator and training ground, with an expectation and attendant philosophy that a game that only sold a couple hundred copies ever is perfect ok), the new Gold Banner standard components are of excellent quality.\nThe lunar surface provides a lovely high contrast backdrop for the counters.\nThe lunar surface isn't very exciting, being mostly shades of grey, but it produces a lovely and good contrast backdrop for the green and orange counters. The colours and artwork for the cards and counters are modern retro, by which I mean they are what one might have expected to see in those heady science fiction TV days of my youth, but with the three intervening decades of experience in graphic design and all the advantages that brings along being used. As a result, we have something that visually looks and feels like a pastiche of those bold shows from the past, but thoroughly modern in readability and usability.\nRules & Game Play\nMoonbase Alpha has as its core premise the idea that two mining companies on the moon are fighting it out, both literally and figuratively, for access to the best mining and resource sites on the lunar surface. There are three aspects of the game play that need to be paid attention to: the stock price of both companies; the lawsuit being fought back on earth; and the actual fighting on the moon. The rules for the game resonate strongly with the theme, and are not only well written and clear but also include plenty of examples. The start player is the last person to have walked on the moon, and from that statement alone you can infer just how fun the rest of this game is!\nThe players start in opposite corners of the board and have the same set of counters to begin - one media unit and three military units. In addition, each players is dealt five cards from the technology deck, which represents the R&D departments of either company. The rest of the cards are unused and set aside for the rest of the game.\nThe intervening spaces on the board are divided up into areas and movement can take place across area borders. Spaces with a mountain icon are cratered areas that cost extra movement to enter, and those with pickaxes are mining sites, and the little flasks represent areas of scientific interest. Areas are controlled individually by the side that has the largest number of units in it.", "336" ], [ "Introduction\nAll summer they drove us back through the Ukraine\nSmolyensk and Viyasma soon fell\nBy autumn we stood with our backs to the town of Orel\nCloser and closer to Moscow they come - riding the wind like a bell\n- <PERSON>, Roads to Moscow\nFighting Formations: Grossdeutschland Infantry Division is the first game in a new series from GMT Games. Much like the Series: Musket & Pike Battle (GMT/Vae Victis), each game in the series will share core rules and the playbook will have specific game exclusive rules.\nThis inaugural game covers action on the eastern front in WWII between the Germans and the Soviets between 1942 and 1943.\nThis is a two player game designed by <PERSON> of Combat Commander: Europe fame (among other titles). Scenarios run the gamut from approximately 2-3 hours for smaller scenarios to a large double map scenario that could fill an entire weekend.\nComponents\nGMT has recently set some impressive standards in wargame publishing. Mounted map boards for single map games like Washington's War and high quality paper maps for multi-scenario games and expansions such as the recent Combat Commander expansion. Beautiful counters that are both functional and nice to look at.\nIn this respect GMT has delivered the goods again.\nThe box however is of the old school thin cardboard style that GMT has not used in a long time. A small quibble is that they used a standard 2\" box rather than the thicker 3\" box; this is a mild disappointment as there is a lot packed inside. Everything does fit into the 2\" box even using two counter trays, but you'll need to split the card decks to make it even along the top. If and when expansions come to this module of the series, it might not fit.\nThe smaller box shouldn't be seen as a deterrent however. There will be more games in the series and those linear feet of shelf space fill up awfully quickly with the larger boxes. I should know, my closets overflow with games.\nThe maps are very attractive and functional, although I found the colour contrast to be muted when compared here with the Combat Commander maps; as you can in the photo here, the Combat Commander terrain features are more easily seen than with the Fighting Formations maps.\nComparing the maps in Fighting Formations (left) to Combat Commander\nWhat's also abundantly clear here is that the Fighting Formations' maps are larger than your typical Combat Commander scenario.", "993" ], [ "The introductory scenario in Fighting Formations uses a half sheet map like Combat Commander, but the other scenarios are all on full and in some cases even double map sheets.\nThe maps are historical depictions of parts of the eastern front. The scenarios all come with a nice long historical background to give the sense of the events about to unfold on the board.\nAnd... for those who felt they were missing from Combat Commander, yes folks, Fighting Formation comes with tanks!\nYes, it comes with tanks!\nRules\nThe rules span two volumes: the core rules and the playbook. The rules are not short, covering some 24 pages and the 64 page playbook adds about another dozen pages of game specific rules and some optional rules. The rest of the playbook is devoted to the 10 scenarios, designer and historical notes, orders of battle, and a detailed example of play.\nThe index is included at the back of the playbook, which can be a nuisance when you're looking for something that is actually in the rulebook, especially anything to do with the sequence of play, but a quick photocopy of the index page is a quick and easy remedy. What's important is clarity and ease of finding information, which are a hallmark of <PERSON> games.\nEven newcomers to wargaming would have little trouble learning the game from the rules, and veteran Combat Commander players will find a lot of familiar terminology.\nVictory is determined by victory points, which can be earned one of three ways:\n- eliminating enemy units\n- controlling certain objectives\n- exiting friendly units off the map\nThe player with the most victory points when the scenario ends is the winner.\nGame Play\nFighting Formations is a classic hex and counter game in many ways. We have the standard hexes, tanks and artillery pieces with facing and fire arcs, movement modified by terrain, and counters chock full of information. There are even rules for vehicles moving in reverse.\nAn interesting and deliberate omission are any stacking rules (except for vehicles moving in column). One could theoretically place every single unit in the same hex. It would be extremely foolish to do so, but you can if you really want to.\nThe lifeblood of Fighting Formations is the order matrix shown above. In order to do anything, you must select a cube from the order matrix, and the value of the cube limits which orders you can execute.", "993" ], [ "Pax Baltica: Great Northern War 1700-1721\nA game for 2 players designed by <PERSON> and <PERSON>, and published by GMT Games\n“Alas! I have civilized my own subjects; I have conquered other nations; yet I have not been able to civilize or to conquer myself.”\n― <PERSON> (attributed)\nIntroduction\nI first learned about this game back in 2009. I attended my first BGG.CON and had the chance to play an early revision of the introductory scenario with <PERSON>, he who brilliantly quipped that \"elephants are not panzers\" in his review of Chandragupta, guided by developer <PERSON> who currently has the really interesting looking Cataclysm: A Second World Waron the GMT P500 program.\nI have a long abiding love of block games. I suspect that it's in no small part due to my having been introduced to them early in my indoctrination into the wargame hobby. That and early exposure to the portfolio of block games from Columbia Games, the original creator of the genre as we know it, which was a Canadian company at the time. They're now just across the border from me in Blaine, WA, and I visit and play test their games far less often than I should. But I digress.\nBlock games are not universally loved, and certainly not in the same way that the hegemonic hex-and-counter-and-CRT model of wargames are, but I've always stuck by them and have been amply rewarded with many hours of pleasurable game play as a result.\nAll of which brings me to this game by two Swedish designers about another period of European history that I knew little about (and indeed, there are entire libraries of bits of history I know precious little about), covering the Great Northern War of 1700-1721, a conflict where a Russian led coalition challenged Sweden's established empire in continental Europe and the Baltic.\nComponents, Rules, and Gameplay\nThis game was originally printed in a very limited release by , and it should come to the surprise of nobody who's played it that the designers are big fans of the classic Columbia Games design ethos as the rules follow many of their classic elements, including blocks having letter coded combat ratings indicating both when they get to fire and how effective they are.\nThe rules are very easily absorbed, coming in at only 16 pages, and that includes the table of contents, the random events table, and several pages devoted to the different national factions and special rules for each. If you've ever played a Columbia Game before, especially the ones that began with Hammer of the Scots and beyond, the system will feel comfortable and familiar.\nPax Baltica comes with a really well designed and attractive map.\nPhoto by <PERSON>\nThe important information is easy to see, the colours provide nice contrast, and the iconography is clear.\nB{Image courtesy of <PERSON>\nThe 65 units are all nicely laid out and easy to read.", "92" ], [ "The unit strengths are noted by pips on the top edge.\nAs noted before, I'm a big fan of block games, but one area where I feel Columbia Games outdoes GMT is that their blocks are thicker and sturdier. There is of course the natural tradeoff that thicker blocks mean that stacks of four or more become somewhat unwieldy and need a lot of real estate on the board, but the thinner GMT blocks, especially when you only have one block in a region, are more easily knocked over.\nIn Pax Baltica you will have a limited number of activations each turn, and the number of those you receive for your turn will depend on a die roll. In a nod to speeding the game along, rather than giving you a hand of cards to choose from, you simply roll your d6. A 1 is one action, a 2-3 two, a 4-5 three, and if you roll a 6, an event happens for you instead and you get no activations at all! However, you can't have two events in a row, so if you roll a 6 again on your next turn, you get to re-roll.\nThe game is played in four phases. The aforementioned die roll for actions is the first phase, and the player with the higher die roll goes first.\nFor the second phase, the first player will complete all their activations, and then the second player.\nIf there are enemy units in a space, the third phase, battle, occurs. Battles use the well known Columbia \"A blocks go before B blocks ...\" and defender fires first model, and last a maximum of three rounds.\nFourth and lastly, units in a space must forage for supplies. Each space has a value showing how many forage points it can provide, and army blocks need 2FP each while regimental ones only need 1FP.", "50" ], [ "Unhappy King Charles!\nA game for 2 players designed by <PERSON> B ook of R ULES\nIntended to be\nA T RUE and E XACT\nRelation of\nHis Majesties\nW ARRE upon\nthe C OMMONS\nThis work perfected by\n<PERSON>, London”\n— From the front page of the Unhappy King Charles! rule book.\nIntroduction\nI usually review newer games, but every once in a while I feel compelled to pull out one of my favourites from the shelf and give it a fresh look. This one is still in print and in stock at GMT, and I feel that it's somewhat of an under appreciated gem in the card driven game genre.\nThe English Civil War is a topic that hasn't seen a huge number of games, and that's a shame because it came during an interesting transitional period in warfare. You can play some of the specific battles from this conflict in the first of the Musket & Pike series, .\nUnhappy King Charles! is a strategic level card driven game that takes you through the English Civil War, either as the Royalists or those pesky upstart Parliamentarians. You'll need to be crafty, clever, and perhaps most importantly, quick as your armies seem to not want to stay around.\nComponents\nUnhappy King Charles comes with a paper map of England (and Wales and Scotland) with areas connected by point to point movement. There is a separate rulebook and playbook, a deck of 110 cards divided into early, mid, and late war, player aid cards for both sides, and two sheets of counters.\nI have added two packs of bingo chips in blue and orange to my copy to place on towns rather than the included markers because my knowledge of British place names is limited to the major cities most people will be familiar with. The bingo markers let me read the city names more easily.\nPhoto credit: <PERSON>If I had the opportunity I'd get the map printed on canvas. It's one of the lovelier ones among the wargames in my collection. The cards, although completely fine, are on the thin side - not quite as thick as the ones that came with the first run of Combat Commander: Mediterranean for instance. However, they have a nice linen finish to them and have held up well for me over the years.\nRules and Game Play\nAs mentioned in the introduction, this is a card driven game, but unlike the most common model where you have to choose between operations and events, this deck is split between events and operations cards. Some of the events are playable by either side, but some can only be played by the owning player's faction, and if you end up with some of these in your hand you can only use them for a limited set of things. The deck is never reshuffled so if an event you really wanted doesn't get into your hand, then tant pis.", "92" ], [ "Or as the designer puts it himself, the event still happened, it just didn't have the same impact in the game as it did historically.\nSpeaking of history, this game is unusual in that it includes some so-called alternate history cards containing events that didn't actually happen but were entirely possible. For instance, there's a card featuring <PERSON> and his army that can enter the game on the Royalist side. I really feel this adds a nice nuance to the game as it inserts a little bit of \"what if?\" without really affecting the narrative flow of the game.\nThe game lasts until either the end of winter 1645 (the 11th and final turn of the game), or an automatic victory occurs. For the Parliament player, this means forcing King <PERSON><PHONE_NUMBER> (the 11th and final turn of the game), or an automatic victory occurs. For the Parliament player, this means forcing King Charles to surrender. For the King, it means seizing London and also controlling three areas on the map.\nThe map is split into five regions. The south, the Midlands, Wales, the north, and east. Each area has a number of towns, and these towns will need to be controlled as part of each player's political base. There are also some areas on the map that are designated as industrial areas, such as the Northumbrian Coal Field and the Forest of Dean. Having control of at least one area like this is necessary or else you will not be able to recruit any troops, and that can quickly send your side into a death spiral as troops are both hard to come by and harder to keep in the field.\nThe game is split into three phases - the early, mid, and late war. Each phase has a mandatory event card that kicks off that era. The early war will see posturing and build up by both sides on the first turn until someone plays Raising the Royal Standard marking the start of armed conflict.", "597" ], [ "1989: Dawn of Freedom\nA game for 2 players designed by <PERSON> (and <PERSON>)\n\"What we may be witnessing is not just the end of the Cold War, or the passing of a particular period of post-war history, but the end of history as such: that is, the end point of mankind's ideological evolution and the universalization of Western liberal democracy as the final form of human government.\"\n<PERSON>, The End of History\nIntroduction\nHello and welcome to the latest edition of Roger's Reviews. I've been playing board games since I was a wee lad and wargames for over thirty years.\n1989: Dawn of Freedom follows in the footsteps, both literally and figuratively of the best selling game from GMT, Twilight Struggle. 1989 covers the events of that tumultuous year as the people of Eastern Europe and the Balkans shook off the shackles of their Communist regimes, with the most visually compelling one being the fall of the Berlin wall, symbol of the Iron Curtain since its erection in 1961.\n<PERSON> berlin 1989\nPlay\nI was a play tester for this game (I'm even listed in the credits at the back of the rule book) through the wargameroom.com league and have watched the evolution of this game from an early inception to this gorgeous new GMT release. I have also previously reviewed a print and play edition of this game (cf. ).\nPhotos in this review are used with the kind permission from <PERSON> (psicoserra).\nComponents\nGMT has outdone itself with this game, with one of the nicest game boards I've had the pleasure of playing on.\nThe colour contrasts for the different countries are clear and clean, the scoring track harkens back to the original Twilight Struggle with the +/- values on the track, the graphics are easy to see and read, and all the symbols are listed in the legend on the board. There are even spaces on the board for some of the key events, and the event tokens themselves are in full colour with artwork to easily distinguish them from one another.\nThere are two decks of cards in the game: the 110 card event deck split into the early, mid, and late war, and the 52 card power struggle deck for resolving scoring phases in the game. Counters are thick die cut counters with a nice heft and feel, with very clear easy to read large numbers. I might have to get a second set to use with my Twilight Struggle game. Yes, they're that nice.\nSomeone went to a lot of effort with the graphic design on this game, and it really shows. The event deck cards are easily sorted by early, mid, and late year by the colour stripe across the top, and the stars tell you whether it's a Communist, Democrat, or rare neutral event.", "92" ], [ "However, in the power struggle cards, while they are suited, in one of those \"that seems obvious in hindsight\" moments, I feel it would have been really helpful to put the elite, church, and worker symbols on the leader cards. Once you've played the game a few times it's easy to remember that you need to control the church space to use the church leader card, but with everything else so nicely designed with icons, it seems an unfortunate omission.\nDid I mention the gorgeous board? Stunning. Really.\nRules & Game Play\nAlthough there are some differences in the final rules, I will refer readers to my old review for the core mechanics and focus on the game play in the GMT edition. As a veteran Twilight Struggle player, I will also comment on some of the core differences between the two games; comparisons between the two are inevitable.\n1989 follows the basic premise of the Twilight Struggle game engine. We have a shared deck split between the early, mid, and late year. You can use cards either for operations or events, opponent events in your hand will trigger when you play them, and events with an asterisk on them are removed from the game.\nRelative to Twilight Struggle, events in this game are rather more dramatic in effect. For one example, The Legacy of 1968 allows the democrat player to put 1 support point into each and every space in Czechoslovakia that is not communist controlled. There are also more linked events in this game, such as the Sajudis + The Baltic Way + Breakaway Baltic Republics chain that has to be played in order.\nAdding to the interesting tension in the game, of the 110 event cards, 90 of them (82%) are starred events, meaning they leave the game when played. In Twilight Struggle that ratio is much closer to half. There are 44 communist events, 14 neutral events usable by either, and 42 democrat events. You spend your events at your peril, but it's even more harrowing to play a 2 ops card that lets your opponent remove 4 of your support points from the board!\nThe direct consequence of this is that hand management is incredibly fraught with peril.", "597" ] ]

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[ [ "Treehouse Bunkbed\nIntroduction: Treehouse Bunkbed\nWe live in a small apartment and with our second baby we needed a safe space for our children to sleep. As their age difference is small (toddler of 2yrs and baby of 7mo) they can sleep together in the same room but the baby is not allowed to crawl out of bed, while our oldest should have some protection from falling but can climb out if he wishes.\nThat is why we opted for a toddlers bunk bed (150cm x 70cm) which can be (partly) closed for protection.\nSupplies\n* Toddler-sized bedframe\n* MDF 2440x1220mmx18mm 4x pcs\n* Screws (4.0x20mm, 4.0x30mm, 3.6x35mm-black)\n* Drilling machine (x2)\n* Jigsaw\n* Sandpaper 220p & 80p\n* Primer 1L\n* Paint 2,5L\n* T-Hinge 7x\n* Handle 5x\n* Paint rollers\n* Degreaser\n* Measurement tape\nStep 1: Frame\nI was not comfortable enough to make a strong frame so we bought this at blankenhoutenmeubel.nl to start of as a base. It came with a white primer, a stairs which we didn't use and two drawers for beneath the bed. Exact size is 161cm x 81cm x 170cm and we estimated it to be 220cm in height after the roof was finished.\nBottom bunk is 23cm from the floor to leave space for the drawers and the top bunk is 110cm from the floor as this leaves enough headspace for both children.\nAfter sanding & painting the bedframe, the first challenge was the support for the roof as this was lopsided and designed in a freeform, trial-error way. I wanted it to be 50cm in height from the bedframe and have an asymmetric look. When we were satisfied we copied these beams for the front and started sawing the planks for the backside. It would serve as support for the support-beam itself strengthening the structure.\nStep 2: Assembling\nTo give it an extra home-made look we sawed each plank with different widths.", "787" ], [ "This was an idea heavily inspired by Mathy-by-bols and kids-playhouse. I made up a numbering scheme for each width of the planks which would total the whole width available:\ntopside plank width:\n9 15 7 11 5 13 5 9 11 13 7 15\ndownside plank width:\n15 7 13 11 9 5 13 5 11 7 15 9\nAs in the previous picture we thought hard and long how to cut the planks on the top side where the roof would be, but in the end we made a small calculation error and it was off by a few centimeters. The support beam was in front of it so you can't see though and once that was assembled we had a first good look at how our house would look like!\nFrom here on we could add the second support beam on the front with an extra plank across the tip of the roof for extra strength.\nStep 3: Little Doors\nAfter finishing the support beams, backpanel and sidepanels it was time for the most interesting part: the little doors which should be cute, practical and protective for both children.\nThe lower left door is 78cm x 92cm made out of 7 planks <PHONE_NUMBER> -- 8 9 12 11 7 11 12) and the two windows are 66,5cm x 65cm (7,5 9,5 12,5 10,5 8,5 11 -- 12,5 7,5 10,5 8,5 11,5 9,5).\nOn the inside of the doors we made small strips to hold all the planks together. Later we had to adjust this a little so it would not bump against the bedframe and we had to cut off corners where it would hit the roof.\nStep 4: Finalize\nWith the doors in place the project was almost finished. Meanwhile we sawed the roof to our liking where we made it a few cm longer on the sides and top which looks very playful.\nIt was time to do the finishing touches for the few planks missing on the front size below the roof and more decorative planks around the entrance for the bottom bunk. In the window we sawed small strips for the window frame to project small babies from escaping.\nLast thing to design where the wooden locks for all three doors. This simple solution works perfectly, but I had to cut out a little bit of the upper doors and fixed an extra wooden block onto it.", "443" ], [ "Simple Green Roof Play House Extension\nIntroduction: Simple Green Roof Play House Extension\nThis project has been on my mind for a while and this year I finally went ahead and made it. The plans have changed multiple times but ended up being really basic and straight forward. This means it could be put up in a day or two.\nTo be clear: this project is about the roof extension to our existing garden shed and not about the shed itself. The part that is covered in this instructable can be seen in the schemes attached to this step.\nI have provided the measurements I used for this project, in milimeters, simply because that's what I needed for my situation. Of course a project like this will be different for everyone, which is why I will not focus too much on the measurements and more on the process.\nAlong with the play house I added a terrace floor and path to our garden which I will include in this instructable.\nEven though the final result is a very basic roof structure, it provides the children a dry and shaded play area which can change function along with their imagination. I hope you'll enjoy reading my building process.\nSupplies\nTools:\n- shovel\n- ground drill\n- saw\n- drill\n- spirit level\n- tape measure\n- pencil\n- wire\n- sticks\nHardware:\n- screws (different sizes)\n- nails\n- steel brackets\nMaterials:\n- wooden posts, about 3x3\"\n- wooden beams, about 2x3\"\n- wooden planks/siding, about 0.5x8\"\n- tar (if you use soft wood for the posts)\n- sedum trays for the green roof\nOptional:\n- sand\n- gravel\n- terrace tiles\n- curbstone beams or blocks\n- anti root cloth\n- interior decoration (lights etc)\nStep 1: Preparation & Ground Work\nOur starting point is shown in the first picture above. Because the white gravel got dirty we decided to use that elsewhere and replace it with a darker gravel for the path and terrace tiles inside the play house. I removed all the gravel and washed it clean (this may have been the most time consuming part of the whole build).\nNext I layed out the plans for the house and path with a wire and some sticks to make sure I didn't remove too much grass. The wire also helps to keep the curbstones level in a later step.\nI based the dimensions for the house on the amount of space available and a combination of the terrace tiles and sedum roof trays that would both fit into the same area. I ended up making the house about 4ft x 5ft.\nI removed quite a bit of earth to make space for the sand and gavel.", "431" ], [ "Be sure to keep some of the removed earth in case you get too enthousiastic (as I was) and might need to put some back later on.\nStep 2: Columns\nOnce the area is cleared of grass and your play house dimensions are layed out, the next step is to place the posts in the ground. This can be done several ways, including concrete or steel foundations, but I chose to use only wood instead.\nIf you use hardwood for the posts they can be placed in the ground without treatment. Softwood however will need to be treated to prevent rotting when exposed to wet ground for long periods. I used a black tar for this, which needs to be applied to a little above the ground level.\nTo secure the posts firmly in the ground the rule of thumb is to put about a third (1/3) of the posts into the ground. I wanted the lower part of the roof to be about 1,3m or a little over 4ft above the ground, so I put them around 0,6m or about 2ft into the ground.\nTo create the hole for the posts to sit in, I used a ground drill. This way you don't need to dig a huge hole and fill it up again. Make sure the hole is a little deeper than you need. Put a bit of your 'levelling sand' into the hole so you can stamp it down with the post and create a steady base for your post and not have it push down into the ground when you put the roof on.\nUse the spirit level constantly when putting in the posts to make sure they are level and straight. I kept measuring the distance between the posts and used the curbstones to keep the posts in place a bit.\nOnce the posts are in the right place and are straight you can fill the hole with sand until it is packed tight. Poor some water over it so the sand can settle and keep adding sand until the hole is filled up and the posts are secure.\nThe next thing to do is to mark the posts at the correct height so they can be cut off in order to place the beams.", "959" ], [ "Wooden Bench With Storage\nIntroduction: Wooden Bench With Storage\nThis bench offers a few extra seats at the dinner table and comes with a lot of -invisible- storage space. Perfect for arts & crafts supplies, board games or extra pillows and blankets. The best thing is that you can make this bench in a day (or two if you want to paint it). Just follow this guide and you'll be sitting on your own bench in no time!\nSupplies\nTools\n- jigsaw or miter saw\n- drill\n- wood drill bit 2mm\n- screwdriver\n- pencil\n- tape measure\n- sanding paper\n- masking tape (or other removable tape)\nHardware\n- 32 wood screws 4x80mm\n- 36 wood screws 3,5x40mm (minimum, recommend buying extra)\n- 48 wood screws 3,5x20mm (based on 6 screws per hinge)\n- 6 hinges (2 for each lid)\n- 6 steel corner brackets 100x70x30mm (or similar)\nWood (see shopping list for dimensions and amount)\n- wooden beams 44x44mm\n- wooden carpentry panels, thickness 18mm\nOptional supplies\n- wood filler or putty\n- paint or lacquer\n- paintbrush\n- paper or sheet to protect the floor while painting\n- felt pads (floor protection)\nStep 1: Preparation\nWhat makes this a quick project is that it requires only a few different parts in only a few different shapes and sizes. All component dimensions are based on standard sizes for each part, resulting in very little left over materials.\nNote that standard sizes may differ from the stores here in The Netherlands so be sure to check your local store in order to get the most out of your material.\nMost hardware stores around here have a service to saw the wood you buy for free or for a very small fee. This saves you a lot of time cutting all the pieces to size and makes it a lot easier fitting everything in your car ;)\nIf your store doesn't provide such a service just print out the shopping list and cut all of the pieces to size before we begin assembly in the next step. In case the wood has any rough edges from cutting, use the sand paper to smooth them before continueing.\nStep 2: Frame\nFirst make sure you have the right components at hand and make 2 sets of the following parts:\n- 2 long beams 44x44x2244mm\n- 4 short beams 44x44x312mm (the shortest ones)\n- 8 wood screws 4x80mm\nLine up the parts on the floor and ask a family member or friend to hold the parts in place while you drill the holes.\nGet your drill and wood drill bit to drill the holes for the screws so that they don't split the wood.\nIMPORTANT: do NOT drill the holes exacty in the middle of each beam, but off to the side a little bit. Otherwise the screws connecting the second part of the frame will cross the first screws and might get stuck halfway into the wood. Keeping the screws about 10mm apart will do the trick.", "250" ], [ "This means drilling the hole about 5mm off center. If you want you can mark the places to drill with a pencil to make sure you start drilling in the right spot.\nDrill all 16 holes (8 for each set) and screw in the screws fixing the parts together to make 2 identical frames like in the 3rd image.\nNext get the remaining 8 wooden beams (44x44x406mm) and line 4 of them up with the 2 frames. The easiest way to do this is to place the frames upright and put the short beams on the floor in between. Take 8 wood screws (4x80mm) and place them at each connection.\nGet your drill and drill the 8 holes for all connections and screw in the screws fixing the parts together. Make sure you do NOT line up these screws with the ones that are already there. Keep them about 10mm apart.\nOnce the first 4 beams are firmly attached to both frames creating a u-shape you can carefully flip the frame over creating a n-shape. Place the last 4 short beams on the floor at each of the intersections. Repeat the previous action and drill 8 holes and screw in 8 screws in order to attach all parts creating a box-shaped frame like in the last image.\nIf you like to be extra safe you can add some additional brackets to the frame (see Step 4, image 4).\nStep 3: Front and Side Panels\nBefore moving on to attaching the panels to the frame, make sure the frame is as level as possible. Wooden beams can be twisted slightly which means the box frame you just assembled can be a little bit wobbly at this stage. Do not worry, this will all work itself out in the end!", "56" ], [ "Hexagon Shelf\nIntroduction: Hexagon Shelf\nHexagons are the best and I had a blank wall in my livingroom. Putting one and one together, I wanted hexagonal shelves in my livingroom. The ones I made have a stained wooden outside, and a white inside. The hexagons are designed to be assembled without screws to keep the structure. The shelves have a wooden back used for reinforcement and mounting.\nI had previously already made a set of three, so the three made here needed to be a good match to the ones I already have.\nSupplies\nTo make 3 shelves I used:\n* 18mm Solid finger jointed panel 30x200cm (This is I think the right name, but in dutch we call it \"timmerpaneel\")\n* 9mm plywood sheet 61x122cm\n* 6mm dowel pins\n* Woodglue (I used polyurethane woodglue)\n* White paint, primer and Oak wood stain (use whatever paint you fancy)\n* Caulk plus finishing materials like soapy water\n* Screws and plugs for mounting the shelf\nThe tools I used:\n* Table saw\n* Miter saw\n* Jigsaw\n* drill with 6mm wood drill bit for the dowels\n* drill for the mounting hole and countersinking bit\n* 2 small ratchet straps\n* 1 glue clamp\n* Paint tools\n* Caulk gun\n* Hammer drill with right stone drill for the plug (for mounting the shelves)\nStep 1: Cutting the Sides\nThe shelves are each made from 6 pieces of wood, each cut to 30 degrees on either side. A miter saw was used to cut the whole board in 9 strips with roughly 18.7cm on the short side 20.5cm on the long side. If you are making your own, the exact dimension is not important, only the angle and that all planks are the same. Mine needed to match a previous set, so I needed to be precise here.\nEach cut the board is placed against a hard stop which my saw has, and then the cut is made at the 30 degree angle. The board is then flipped, placed against the stop and cut again. This step is repeated until you have the desired amount of pieces. Be sure the plank does not move while cutting. With angled cuts the saw tries to move the plank sideways, ruining the cut.\nMy board was 200x30cm, which yielded me with 9 strips of roughly 20x30cm. I want my shelves to only be 15cm deep, so with a table saw I halved each plank. This gave me 18 planks in total, making 3 shelves.\nStep 2: Cutting a Slot\nTo hide the back board of the shelf, a slot needs to be cut in the wood, roughly half the depth of the plank (in my case 9mm). It needs to be at least as thick as the back board, which in my case is also 9mm.", "431" ], [ "I made an 11mm wide, 9mm deep slot. This slot is on the side which was cut, so the clean chamfered side becomes the front. Make sure the slot is in the short side, else your slot will be on the outside of the shelf.\nThe table saw is set to 9mm tall. The fence is set so the cut is around 8mm from the back edge of the plank. Then each piece is carefully cut on the saw. The fence is then moved to make another cut with the furthest edge 18-19mm from the back edge. The final cut is placed somewhere in the center. I was left with two thin strips of wood which I removed with a chisel. if you are willing to make another cut you can simply remove all the material with the saw.\nStep 3: Dowel Holes\nThe shelf is held together with dowel pins. Each plank has three 6mm dowel pins per side.\nTo make the holes more accurate I made a 3D printed tool to align my drill. I have included versions of this tool with 5, 6, 8 and 10mm holes. I used the 8mm one with a metal bushing, but if you are careful the tool should last at least a few shelves. The tool needs to be oriented with the side with the holes on the printbed.\nIf you cannot make this tool, you can simply drill 3 holes in each side, and then use dowel center pins to mark the dowel holes in the other side of the plank before drilling.\nStep 4: Making the Back\nThe back is made of plywood. This back provides strength and place to mount the shelf. Measure the inside of the hexagonal shelf, and mark this shape on the wood, with enough allowance to fill the slot in the planks. A jigsaw was used to cut this shape out of the plywood once.", "599" ], [ "DIY Loft Bed\nIntroduction: DIY Loft Bed\nIf you have a small apartment, then a loft bed is a great way to get some extra space. Our apparent doesn't have high ceilings and so the bed needs to be fairly short, but we still gained a ton of extra storage.\nTo make this project you will need a little bit of experience, but it still is very simple. There are no complex joints and you should be able to make it even with limited tools.\nSupplies\nTools\n* Cordless drill\n* Drill press\n* Table saw\n* Circular saw\n* Random orbit sander\n* Palm router\nMaterials\n* Rough lumber or\n* 2x8 – Sideboards and supports\n* 2x4 – supports\n* 3x4 or 4x6 for the legs\n* You can find the exact dimensions in the PDF plan below. However, you will probably need to adjust it to your mattress size and lumber.\nStep 1: Legs\n* If you are starting with rough lumber, you will have to run it through the planer and jointer first.\n+ I had some fairly thin roofing battens laying around. Because I wanted the crosssection of the legs to be 100x60 mm, I had to glue 4 of these battens together.\n* However, you can get a 3x4 which is 63x90 mm or a 4x6 which is approximately 90x140 mm. This means that you will just need to cut it to length, sand it smooth and chamfer the edges.\n+ This is definitely a much faster and easier way to go, so I would definitely recommend it.\n+ Just make sure that the 3x4s or 4x6s you get are straight.\nStep 2: Boards\n* I made all 4 of the boards 30x200 mm while cutting the sideboards to 1860 mm and the headboard and footboard to 1600 mm. The lengths will vary depending on the size of your mattress as well as the crosssection of the legs.\n* The first step was to cut the rough lumber to more manageable pieces and then to run them through planer and jointer and finally to cut them to length.\n* The more efficient way is to get a nicely straight 2x8 boards which are actually 38x184 mm and just cut the 4 pieces of appropriate length out of it.\nStep 3: Supports\n* Next, supports for the mattress need to be made.\n* There will be two supports (side supports) screwed to the inside of the sideboards. They will be 30x50 mm and almost the same length as your mattress (make them about 10 mm shorter)\n+ If you are using 2x8s for the sideboards you can just cut an extra 2x8 board into 4 strips.", "431" ], [ "The support will then be roughly 40x38 mm, which works too.\n* The middle consists of two 30x50 mm strips glued together to create a 60x50 beam.\n+ The middle support has is secured to the front and back board using wooden pegs and M8 bolts with barrel nuts.\n+ To reinforce it there is a leg in the middle as well. The leg sits in a recess and is secured to the middle support with two decking screws from the top. The holes for the screws were predrilled because I didn't wanna risk splitting the leg. This can be made out of a 2x4.\nStep 4: Mattress Grate\n* We are making 2 grates, one for each half of the bed.\n* I made each grate out of 14 15x30 mm strips, so we will need 28 pieces in total. The strips should be about 5 mm shorter than half of the width of your bed.\n+ If you are using a 2x8 board you can just cut 15 mm wide pieces out of it. But you will need to adjust the spacing of the grate.\n* Then we connect the wooden strips with upholstery webbing, using a stapler. A spacer of the right length makes this process fairly quick.\n* This way, you will just need to fix the first and last strip to the bed frame, the rest of the grate will be fixed in place by the webbing.\nStep 5: Connecting the Parts\n* Sideboards are connected to the legs and middle support with 12 mm wooden dowel pins, M8 bolts and barrel nuts.\n* The holes that are drilled in each mating part have to be reasonably straight and accurately spaced.\n+ Therefore, I made a simple jig with a hole pattern. It is made out of hardwood (oak) for better wear resistance and it has a backside to help with the alignment.\n+ Drilling through this ensures that all the holes are perpendicular to the surface and have the same spacing. This is critical when you want all three dowel pins and two bolts at each connection point to line up.", "599" ], [ "Wood Playground\nIntroduction: Wood Playground\nIt all started when I looked to buy a playground to my daughter. While looking to pre-built module from regular shops, I told to myself: \"hey, that doesn't look complicated. Seriously, how hard can it be?\"\nFrom that point, I started looking online for inspiration, starting to draw something fitting my garden. After many loops, I finally found the perfect design, according to me.\nCriteria were having a main cabin, big enough for an adult to be in (at least to tidy it up when messy), a second floor for when the children are bigger, a swing and a slide. Additionally to this, I wanted the whole thing to be scalable over time (e.g. add a monkey bridge in a few years).\nEverything was designed using CAD for ease (it's nice to refer to a plan sometimes), which evolved a bit during the construction. Attached is the actual design of it, feel free to use or modify it for your own personal projects.\nI'm sorry if I misuse technical terms, I'm not a professional wood worker, nor English is my primary language.\nSupplies\nI used impregnated pine so I didn't had to treat it after (hopefully).\n* Main structure is made of 9x9cm posts (~55m)\n* and 7x7cm posts (~100m)\n* floors are made of 14.5x2.8cm planks (~110m)\n* walls are made of 14x1.6cm planks (~90m)\nThe main tool I used was a miter saw (bough one for the occasion, no regrets). Beside of this, a good drill was essential.\nStep 1: The Main Structure\nThe whole structure is based on stilts.\nAs mentioned, structure is made of 9x9cm posts as vertical studs and 7x7cm posts as horizontal joists. I guess it's not that common to use square section wood for joists, but all in all it was easier to find square section posts (and then cheaper) than rectangle ones, when speaking about class 3 impregnated pin.\nStructure is not directly in contact with grass, to avoid rotting (even if 9x9 studs are class 4 and should not be damaged by direct contact with water). Better be safe than sorry.\nI used galvanised steel anchors (~70cm high) to support studs. They are simply sunk in the ground.", "431" ], [ "The 4 ones around the swing however are loaded with concrete (quick concrete, dry in 20 minutes), so the pendulum movement doesn't move them over time.\nI made a grid using strings planted in the ground to have the perfect location of every anchor. But even with that, a lot can happen when sinking 70cm of steel into the ground. Most of them are not straight, but that could be corrected with the play in the wood. Once done, errors in the anchors doesn't matter.\nStep 2: Attaching the Joists\nI thought about this part for longer than anything else. Not being in the wood world, nor having experience, nor having professional tools led me to drop all wood arrangements you would normally see (and use way more steel...).\nI used a steel square (4x6x6cm), screwed in studs and tied to joists with an M8 nut and a security bolt. Joists posed on other joists are simply screwed.\nStep 3: Adding Triangles, Adding Support\nBecause rectangles tend to transform themselves into parallelograms, I needed to add triangles.\nFor this, I cut (a lot of) piece of wood (about 45cm, cut at 45°) to reinforce the structure. As the structure was not straight before starting, I used straps anchored to what I could find or bring, and straightened everything.\nTo get a good result (being alone to fix them), I tied them hard with clamps and wood falls (the piece you get when you cut the edge of a pole at 45°), then screw them in place. This technique was amazing, and ensured the reinforcements stayed in place, before and during screwing.\nIn doubt (and also because I like the aesthetic of it), I put them everywhere I could. That's probably too much and I could have dropped some, but once again I'm not a professional, better too much than not enough.\nStep 4: Floor and Wall\nStructure being over, time for closing the cabin.\nNothing really complex in this step. Everything is screwed to joists or studs.\nHopefully, I did this when weather was bad for several weeks, and planks were swollen. So when they were fixed, I didn't need to pay too much attention to dilatation space.", "787" ], [ "Bending Wood / MDF\nIntroduction: Bending Wood / MDF\n“Where the curve starts a proper earning ends” my grandfather, a carpenter by trade, used to say.\nWell, after some experience gained I totally agree with him. Compared to angular joints curvy and bendy shapes made of wood take an infinite time longer to make. The best way to bend wood and medium-density fibreboard is by the use of steam. Since I don’t have a steam chamber I was looking for an easier way for an aspiring project, the make of a flowerbed for my balcony.\nThis Instructable shows a technique almost forgotten – shaping wood and medium-density fibreboard by watering it and the use of ammonia.\nSupplies\nThose are the things you need:\n* several clamps\n* Ammonia (I used a 10% solution)\n* spray can\n* tension belt\n* wood glue\nPLEASE NOTE: ammonia solution, or ammonium hydroxide, to be precisely, is an extremely hazardous liquid. It was widely used as a household cleaner until a couple of decades ago. The stench is almost unbearable.\nAlways wear goggles, gloves and a mask and apply it only on the outside!\nStep 1: Soaking the Wood / MDF\nThe principal idea is to bend small layers of wood and / or fibreboard, let them dry and then glue them together.\nFirst I sprayed the cut pieces with a 10% ammonia solution on both sides. I did this twice and let everything dry for a day.\nThen I watered the pieces.", "254" ], [ "The strong stench of the ammonia is nearly gone, I did this in my shower cabinet.\nStep 2: Bending It in Shape\nAfter the soaking I bent the pieces around the shape they should take and fixed everything with clamps.\nI left it that way for a couple of hours, then took it off and fixed it by the use of a tension belt. This is for letting the material dry off, also for keeping the shape (it would otherwise go back to almost normal).\nStep 3: Glueing Everything Together\nA day later you can start glueing everything together. Take wood glue and coat the entire contact area. Again put it around the shape or a pattern and press it as strong as possible together. Let it rest for 24h and take it off.\nSometimes some smaller spots on the edge between the layers didn’t properly stick together. I inserted wood glue into the gaps and pressed it again with a clamp.\nStep 4: Finishing\nI made the bent part of the flowerbed out of two layers of MDF, about 8 mm thick, and a thin layer of wood with a thickness of about 2 mm. The latter was for the visible surface, it shall match with the other parts of the construction.\nIMPORTANT: Since it is almost impossible to measure the proper length of a curve before, make sure all the pieces are a bit oversized and do the cutting later in place.", "556" ], [ "Removable Spray Booth for My Workshop\nIntroduction: Removable Spray Booth for My Workshop\nSince some time I wanted a place to play around with spray colors and varnishes. For small items I helped myself with cardboard boxes, but larger pieces so far were out of reach. So I set out to build myself something which was\n* easy to build\n* removeable\n* cheap\n* fit for purpose\n* materials easily available\nMy DIY shop is an unheated room in the attic of my house, with plasterboard on wooden frame on the ceiling. So it seemed easy to fix something up there. A quick look around and it became clear what I would do ...\nSupplies\nMaterial\n* wooden strips 20 x 5 mm (or what is available - uncritical)\n* wood glue\n* adhesive tape 40mm (or broader)\n* transparent plastic foil 2 x ### m\n* drywall screws 4mm\nTools\n* backsaw\n* miter box (optional)\n* cutter knife\n* screwdriver\nStep 1: Preparing the Clamps\nFirst I cut small lengths from my wood strips:\n1. length = width\n2. length = 2 x width\n3. length = 3x width\nThen I glued one piece of (1) onto each of (2) and (3)\nNext I drilled holes 4mm into the center of each doubled piece and countersunk on the small surface for drywall screws.\nNote that in the pic you see far too many clamps ... seems I was a bit over enthusiastic about my idea ... I ended up using 2 pieces of L = 3W and 7 pieces of L = 2W\nStep 2: Preparing the Spray Booth\nThe plastic foil comes in various lengths and a width of 2m from my local DIY market.\nAs I wanted a box of ca. 1.4 x 1.4 m, I cut the following lengths of foil:\n1. left side ... 1.7 m\n2. front side ... 1.4 m\n3.", "401" ], [ "right side ... 1.7 m\nThen I cut wooden strips - same material as the clamps - in following lengths:\n1. 1.4 m ... 3 pieces\n2. 0.3 m ... 2 pieces\nI placed the wooden strips at the edge of the foil, wrapped the foil around the strip 2 times to create a tunnel, and glued the tunnel across the full width using adhesive tape. The side walls contain strips 1.4 m plus 0.3 m.\nNow all components were ready to be mounted.\nStep 3: Mounting the Booth\nI screwed\n* 2 x 3-length clamps to hold the edges of the front wall plus 1 x 2-length clamp to hold its center\n* 3x 2-length clamps to hold the left side wall.\n* 3x 2-length clamps to hold the right side wall.\nso that the small surfaces of the clamps touch the ceiling, creating a gap of 1 strip thickness.\nThen I fed the stripped edges of the foils into the clamps.\nFinally I added some rings into places of the ceiling where there is a wooden bar above the drywall, so I could attach the item to be sprayed by a length of wire.\nAfter spraying I can easily pull out the walls, roll them up and stow them away until next use. The clamps and rings remain in the ceiling, they don't disturb.\nDone!\nStep 4: Post Build Considerations\n* Building the booth close to a window where the sun shines in from midday till sunset wasn't the very best choice ... but I had almost no other choice ... so spraying only after sunset ;-)\n* Later on I extended the foils to reach the floor\n* I found it better to install the front wall before the side walls to create an inside overlap ... this seems to keep tighter when the whole foil starts to move as you move\n* I closed the end of the tunnels holding the 0.3 m strips with some adhesive tape because the wood strips kept escaping their tunnels\n* clamps should not be screwed very hard at first ... leave a little play and tighten the screws only once the walls are slid in.\n* Currently the openings of the clamps look toward the inside ... I don't yet know if it's better this way or the other way round ... time will tell ... maybe it doesn't matter at all ;-)", "56" ] ]

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[ [ "2 year old puppy is I’ll\nBeen to the vet several times already and they are unable to diagnose the issue\nMy black lab puppy has blood in her stool and is accompanied by a foul smell as well quite often. We’ve tested for parasites and had her fecal matter tested for Giardia too.\nWe’ve changed from a kibble only diet to one of rice, boiled chicken, and pumpkin purée.\nShe’s mostly great otherwise but it’s been 10 or 12 weeks of this and sometimes you can see that she’s uncomfortable from it.", "664" ], [ "She’s best once she’s expelled everything. Poor girl, I’m hoping one of you can entertain some options here or let me know if anyone else has been through this. I just want her to be comfortable again.\nCheers", "975" ], [ "Need help understanding strange dog behavior that looks like itching but isn’t\nHi friends, Hoping to get some guidance before going deep at the vet and spending a ton of money.\n<PERSON> is a healthy 4yo female Jack Russell terrier. Overall she is very healthy.", "664" ], [ "She has seasonal allergies which we treat with a Cytopoint injection every few months.\nShe is current on NextGuard, and isn’t taking any other meds.\nThis behavior in the video looks like there’s something “crawling” under her skin. She bops at her body with her nose, but isn’t really itching. Her skin doesn’t look irritated.\nShe is obsessed with doing this", "664" ], [ "My cat is sick\nHey any vet here?? Or any pet parent with a Persian cat with some experience regarding this!\nI have a 15 month old punch face Persian cat. In my home country, we don’t have very experienced vets with good technology. I mean we don’t even have ultrasounds for cats here apparently. So some days she drools and becomes lethargic and won’t eat. And some days she is fine and eats normally.", "961" ], [ "Today she’s been drooling a lot and has refused to eat or drink anything. Hee lab work up showed mildly elevated ALTand AST but they’ve both improved from a few months ago. Idk what to do. I feel helpless and we can’t diagnose her at all. She’s not even sleeping today.", "664" ], [ "My yorkie likes to hunt and won’t stop.\nI do not like him doing it. He will come get us and take us to what he was able to get. Last night he had a opossum in the front yard.", "210" ], [ "Luckily, it was just playing dead and we let it go. It really hasn’t been too much of a problem in the past but we moved to a rural area and every time he is outside it seems he is tracking something. He has a different bark when he’s found something.\nHe’s an older dog, is there even anyway to break that now besides making him stay on a chain when he’s outside.", "1011" ], [ "I think my dog is underweight.\nI have a 7 year old miniature poodle and she currently weighs 11lbs. She is really tall and boney, the vet said she has weirdly long legs and was compared a “baby deer” lol.", "63" ], [ "My attempt at getting her to gain weight don’t seem to be working, I add coconut oil, eggs, white potatoes and chicken (all cooked) to her dry food. Which is Natures recipe dog food and she just doesn’t seem interested even tho she’s really greedy when I come to table food/ human food. So any tips on what to feed or what diet to use?\nI recently had to shave all of her hair due to some matting and noticed how frail she actually looks.", "747" ], [ "My cat drools a lot\nHey I have a punch faced Persian, she’s around 17 months old. For the past couple of months we’ve noticed that she’s been drooling every 3rd/4th day. Sometimes she won’t drool at all for a week or two but it always comes back.", "664" ], [ "She also sometimes doesn’t eat much (although she’s always been a picky eater). I have a younger cat that’s around 5 months old and she’s sooo playful but the older one doesn’t even play with her. My sister thinks that her breathing rate is always on the faster side too. Any help would be appreciated, I’m desperate to find out what’s wrong with my baby!!! Thank you in advance!!", "664" ], [ "Kitten won’t stop peeing everywhere\nHello, any help would be greatly appreciated. I got my kitten (10 months old) when he was 2 months old. He used to pee around the house every couple of weeks, now almost every day, 9/10 times when I’m asleep. However, he poops in the litter box.", "311" ], [ "The vet tested his pee and found that he had a bacterial infection. We gave him the medicine, and he should have been responding to it by now, but he hasn’t. The vet recommended a diffuser to calm him down. But it’s a hundred dollars, and I’m not sure if it will work. What should I do?", "833" ], [ "Cat overgrooming\nLower belly and hind legs are bald. I can’t figure out if it’s allergies, infection, or stress. The vet gave her a steroid which helped so this leads me to believe she’s actually itchy and not doing it out of anxiety. We tried food trials, kicking the air purifier up a little more often.", "505" ], [ "She’s been treated for fleas. I’m considering finding a safe antifungal treatment just to see if that does something. She’s always had slight upper respiratory problems which I assumed to be that super common feline herpes virus. I no longer treat it with lysine as it’s really tough on her stomach and I’ll be cleaning cat puke all day.\nShe’s 6 btw\nWhat haven’t I considered yet? What would you try next? I’m taking her back to the vet soon. What should I ask for? Help!!!", "664" ] ]

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[ [ "Guatemala: Maximón and Other Holy Week Traditions · Global Voices\nThis post is part of our special coverage Indigenous Rights.\nWhen a very religious culture becomes dominated by yet another deeply religious people, often the religion of the conqueror is imposed on the conquered. However, cultures have always found ways to offer resistance; in Guatemala somehow the Catholic religion has been “hacked” to incorporate indigenous peoples’ gods, goddesses, rites and ceremonies while integrating elements of Catholicism.\n<PERSON> is the best example of such transmutation, as explained by the photoblog Mi Mundo:\n<PERSON> explains: “In oral tradition, <PERSON> represents <PERSON>, the last ruler of the Maya Kaqchikel people [during the Spanish conquest], who was tied, tortured and murdered. This entire episode is known as <PERSON>, which is surely why they call him <PERSON>: ma refers to a male person in the Maya Kaqchikel language, and ximón means he who is tied up.” According to <PERSON> the syncretism between <PERSON> and <PERSON> began when “the Christian [conquistadores] realized they could not eradicate the image of the great protector of the people. Hence, they began to promote the idea of <PERSON> as being the same as <PERSON>, often related with <PERSON>, a treacherous figure.”\nPicture under a Creative Commons attribution license by <PERSON>.\nThe different and very special elements of religion in Guatemala make the Holy Week (in Spanish, ‘Semana Santa’) quite a unique experience, including characters like the “Cucuruchos“, communities gathering to create holy week carpets made of flowers, and devoted men and women carrying on their shoulders colonial images of <PERSON> and <PERSON> while wearing traditional outfits under the sun, in spite of the hot summer.\nHoly Week is a family celebration where everyone is invited to participate, as the photo blog AntiguaDailyPhoto.com describes:\nAs I’ve mentioned before, the making of carpets from sawdust, pine-needles, flowers, vegetables is a community-forming tradition. People get together by block or near-by neighbors to create the carpets on which the processions will pass by. Sometimes the making of the carpets is done at night, all night so they are ready for next day’s procession.", "186" ], [ "The colorful processional carpet elaboration process involves the whole family, close friends, the neighborhood and the entire community. It does not matter if it’s just grandma throwing some corozo (corozo palms) and dried purple flowers to elaborate a humble alfombra in front of her home or it is a team of members of the cuadra (the block), or if a son lends a hand to a dad to put the final touches on the brightly-colored sawdust carpet, the devotion and the do-good spirit are present everywhere you look.\nHoly week carpet making. Image by <PERSON> www.Antiguadailyphoto.com (CC BY-NC-SA 2.0)\n<PERSON> [es] explains how Holy Week is celebrated in a very different way in Santiago Atitlán:\nEn Santiago Atitlán, el Viernes Santo por la tarde, al igual que en el resto católico del país, da inicio la representatividad de la muerte de Jesucristo, pero a diferencia del mundo ladino, la celebración no tiene connotaciones ominosas. Al interior de la iglesia hay un tumulto de gente que participa en la preparación del cortejo procesional, con tambores y chirimillas, no hay pesadumbre; hay respeto al ceremonial, pero no hay tristeza, ni acongojamiento en el rostro y actitud de la gente .\nIn Santiago Atitlán, during Good Friday afternoon, people celebrate the representation of <PERSON> death, but unlike the non indigenous World, it lacks the ominous character. Inside the church there is a crowd participating in the procession with trombones and “chirimias“, there is no sorrow, only respect for the ceremony, and the faces and attitudes of people attending do not denote suffering or sadness.\nHoly Week in Guatemala is rich with colors, scents and devotion. It is a cultural, spiritual and gastronomic experience for locals and visitors in this diverse country with more than twenty four languages and different indigenous groups. The best of different worlds come together to enjoy and find beauty in mixing, rather than imposing, their culture.\nThis post is part of our special coverage Indigenous Rights.", "186" ], [ "Guatemala: Esquipulas and Rabinal, Two Symbols of Peace · Global Voices\nPhoto by <PERSON> of Cofradía en Rabinal\nTwo villages in Guatemala celebrate very important festivities in January. These feasts are “Esquipulas” and “Rabinal”. Esquipulas has become a transnational celebration and attracts devoted pilgrims that arrive from other countries in order to venerate an image of a Black <PERSON>. This was also the symbol of the Peace Negotiations througout Central America. The image of <PERSON> in Esquipulas is a special one as Hecho en Guatemala [es] explained on his post Esquipulas, city of faith\nEl referido Cristo, es una imagen de <PERSON>, a la cual, millones de devotos de Centroamérica, le rinden culto desde hace más de 400 años en el templo católico que lleva el nombre de este pintoresco poblado. El adjetivo de “negro”, se debe a que con el paso de los años (según muchos, al humo de las velas), el color de la madera en que fue tallado el cristo, se fue tornando oscura, hasta adquirir el color negro de la actualidad.\nIt is an image of a cruxified <PERSON>, which millions of Central Americans have been devoted to for the last 400 years, and is located in the church with the name of the picturesque town.", "186" ], [ "The adjective “black” is due to color of the wood of the sculpture turned dark (according to many, due to the smoke from the candles), and nowadays it is black.\nEsquipulas is located in the department of Chiquimula, but the faith and devotion for the image crosses borders, according to El nuevo blog de Esquipulas [es]:\nLa devoción por el Señor de Esquipulas ha trascendido fronteras hasta hacer de <PERSON> la ‘Capital Centroamericana de la Fe’ y también ha sido adoptada por católicos latinoamericanos residentes en Estados Unidos. Esta tradicional celebración del ‘Señor de Esquipulas’ se viene llevando a cabo anualmente en los diferentes condados de la ciudad de Nueva York y desde hace tres años se celebra en la Catedral de San Patricio, gracias a las gestiones de la señora <PERSON>, cónsul general de Guatemala en Nueva York y la Hermandad Arquidiocesana del Señor de Esquipulas NY. También se festeja en Nueva Jersey y finalmente la solemne celebración culmina en el condado de Brooklyn.\nDevotion for the Christ of Esquipulas has crossed borders and has made Esquipulas the Central American Capital of Faith, and it has also been an image that has been adopted by Latin American Catholics living in US. The traditional celebration of <PERSON> has taken place every year in the different counties of New York, and it began to be celebrated in St. Patrick's Cathedral three years ago, thanks to the actions of <PERSON>, general consul of Guatemala in New York and the Archdiocese Brotherhood of the Christ of Esquipulas in NY. It is also celebrated in New Jersey and the celebration concludes in Brooklyn.\n<PERSON> [es] tells what an old lady of his town thinks about the festivity:\nNos Cuenta Doña Clemencia de 85 años de edad, junto a su familia, nos dice que ella tiene aproximadamente 20 años de estar viajando a este Municipio de Esquipulas en estas fechas para darle gracias a <PERSON> por permitirle terminar un año mas, y empezar uno nuevo, a la vez deja su ofrenda en Río de los deseos, para pedirle un deseo a <PERSON> y que se lo haga realidad.\nMrs. <PERSON>, who is 85 years old, tells us that she has been visiting <PERSON> with her family for approximately 20 years to thank God for giving her another year of life and for beginning a new one.", "186" ], [ "Guatemala: The <PERSON> and Other Foods for Day of the Dead · Global Voices\nOnce upon a time, there were a convent in Antigua, Guatemala, where the nuns had been celebrating the All Saints Day, around the 16th of the month, and they had an uninvited, but important visitor. They were really nervous because they did not have enough food to make a proper dinner for the priest, so they used their creativity instead. They collected and remixed all the leftovers from previous meals, from slices of cheese to potatoes. As a result, the Guatemalan <PERSON> was born and the priest was delighted! Nowadays, it is a celebration for the entire family that begins on the night of October 31. The complex recipe [es] has up to 150 ingredients, from vegetables to meats of all kinds, even fish!\nAlso you can enjoy camotes en miel (sweet potatoes) and jocotes en miel, as described by Antigua Daily Photo .\nJocotes (/hoe-ko-tes /) or red mombin are often eaten raw, but you can find them as often in tasty preserves. Jocotes en miel or red mombin in syrup (literal translation of miel would be honey, but in this instance it means syrup or almíbar in Spanish) are prepared as dessert to take to the cemetery on Day of the Dead or Día de los difuntos . The idea is to take foods that are prepared in advance and that do not need heating up or that spoil quickly. That’s why you take fiambre , and whatever fruits are in season prepared as dessert.\nFor many Guatemalans, Fiambre is just too much for some tastes, so some families just order pizza, such as the family of the blogger from Fe de Rata [es] :\nDe noviembre. Día de los muertos. Día de Fiambre, el platillo tradicional guatemalteco por excelencia. Compuesto de carnes frías, vegetales curtidos, quesos, toda suerte de embutidos y cualquier cosa comestible para el ser humano. Gastronomía infernal a mi paladar. No me gusta, mátenme, lo sé.", "186" ], [ "Ese día en la reunión familiar -para recordar a nuestros muertos-, como pizza con los niños y tomo vodka con los grandes.\nNovember. Day of the Dead. Day of the Fiambre, the traditional Guatemalan Dish par excellence . It is made with meats, prepared vegetables, cheeses, all kinds of cold cuts and any food eatable for a human being. Gastronomy from hell, it is just not for me. I don´t like it. During the family festivities – to honor our dead – I eat pizza with the kids and drink vodka with the adults.\nPhoto by <PERSON> and used under a Creative Commons license\nDuring the festivities of Day of the Dead, many places have other delicious culinary traditions besides Fiambre, such as pumpkins, sweets, drinks made of corn, as described by <PERSON> [es]\nLos habitantes de otras localidades del país practican diferentes costumbres. En Comalapa se prepara el cocimiento, hecho a base de elote, güicoy y güisquil hervidos, acompañados de atol de elote y cusha, una bebida embriagante. Elote, camote y güisquil asados son servidos en San Pedro La Laguna, Sololá. En Petén, los niños salen por la noche del 31 de octubre a pedir Ixpasá para la calavera. El Ixpasá es una bebida hecha de maíz negro, la cual acompaña los bollos y tamales peteneros. Se vacían toronjas y se les hace una carita similar a la de las calabazas y adentro se les pone una velita. También se come dulce de ayote, molletes y jocotes en dulce y, por supuesto, el fiambre.El Ixpasá es una bebida hecha de maíz negro, la cual acompaña los bollos y tamales peteneros. Se vacían toronjas y se les hace una carita similar a la de las calabazas y adentro se les pone una velita.", "186" ], [ "Guatemala: Celebrating Earth Day and Ways to Preserve · Global Voices\nPhoto by <PERSON> and used under a Creative Commons license.\nThe name of Guatemala derives from a Mayan word meaning “the land of trees”. Actions in the form of words is the way that I describe the spirit of bloggers telling the world what are they doing to protect and save the planet. From small local governments to desks of people in the city, many bloggers are conscious about the environment and they are telling the world some examples of what we can do, as Mr. <PERSON> says:\nEn Guatemala, Mexico, y varios países de Latinoamérica aun producen sus emisiones de co2, no toman en serio la Alerta, las personas son incapaces de tomar decisiones si el estado de los respectivos países no se preocupa, la crisis energetica es lo que es por el mal actuar, y si ahora no nos preocupamos por este cambio climático, se va avecinar una peor situacion, en la cual no hay vuelta atras. Este va ser el Mundo del mañana que van a vivir las futuras generaciones.\nIn Guatemala, Mexico and other countries in Latin America still produces CO2 emissions, and the countries do not take the alert seriously, people are even incapable of deciding to do something if the State of each country is not concerned. Energy crisis is what it is because of our bad behaviour, and now we are not concerned with global warming, and a worse situation is approaching, there is no turning back.", "398" ], [ "This is the world of tomorrow, where future generations will live.\nBut there are also small actions by local governments that are taking place. The blog a small local government in Quezaltepeque described their actions [es]:\nEntre los distintos bosques podemos mencionar el bosque de Santa Teresa, bosque de Yocón y el bosque del caserío San <PERSON>, en los cuales se han realizado prácticas de reforestación y los cuidados necesarios para evitar que incendios forestales acaben con nuestra flora y fauna.\nAmong the different forests we have Santa Teresa, Yokón and the one near San Juan, in “Muffins” Village, where we have reforested and have taken all the necessary care to protect our flora and fauna from fires.\nAmong the different posts was the one by <PERSON>,\nConsidero que el dia de la tierra se empezó a celebrar justamente en el primer minuto cuando una primera mujer o un primer hombre de lejana comunidad prehistorica se alegró de descubrir el agua para beber, el fuego para cocinar y abrigarse del frío, el suelo para cultivar, el aire que le tonificó cuando cansado salió a la orilla de su cueva en la parte más alta de su casa en la montaña y llenó sus lpulmones y se sintió como nuevo, y todo esto y más aún nos dá la tierra. El celebrar el Día de la Tierra forma parte de una estrategia de concienciacciòn y educación ambiental, pero es necesario que nosotros como ciudadanos del mundo de nuestro país Guatemala, el cambiar nuestra forma de vida y de consumo, de proteger nuestra riqueza natural y sobre todas las cosas el “agua”.\nI think that the first celebration of earth day took place when the primitive man or woman from a prehistorical community was happy to first discover the water to drink, the fire to cook and warmth, the soil to grow crops, the air that purified him when he went out of from his cave at the top of the mountain and breathed and felt renewed. All of this and more is given by the Earth. To celebrate the Earth is part of a strategy of environmental motivation and education, but it is necessary that we, as citizens of the world and our country, change the way we live and how we consume. It is necessary to protect our natural heritage and above all “the water”.", "186" ], [ "Guatemala: Indigenous Teacher and Artist Kidnapped and Murdered · Global Voices\nThis post is part of our special coverage Indigenous Rights.\nAn increasing spiral of violence has impacted different communities in rural Guatemala. This time, the victim was a respected rural teacher, spiritual guide, dancer and artist from Sololá: <PERSON>.\n<PERSON> was kidnapped on his way to the rural school were he taught, in Chuacruz, Sololá. His deceased body was found with signs of torture as reported by an official statement from Cultural Center Sotz´il Jay [es], where <PERSON> worked as the director. The blogs Colectivo El Papel [es], Red Maya (Mayan Network) [es], ComunicArte [es], The Pavarotti Center [es] and Quahutemallan [es] also reported the incident.", "497" ], [ "Artists and indigenous groups are mourning the torture and murder of <PERSON>.\nIndigenous poet <PERSON> dedicated a farewell and a poem [es] to her friend and mentor on her blog, Santa Tirana:\nGracias por tus palabras sabias, por ser amigo, guia y hermano, tu fortaleza y tus sueños siguen con nosotros, en mi corazón estan los recuerdos que vivimos como semillas, es difícil entender la mala muerte, esa que deviene del desequilibrio y la maldad, da rabia y da coraje, el dolor corre por mi sangre, por nuestra sangre, pero tambien la luz que deviene de tu espiritu, que ya es latido de viento, sonido infinito, estrella, neblina, susurro de tiempo…\nI thank you for your words full of wisdom, for your friendship, guidance, strength, your dreams are still with us, in my heart are the memories of the time we shared as seeds, it is hard to understand this tragic death coming from the disequilibrium and evil, it causes anger and it frustrates me, the pain that runs in my blood, for our blood, but also the light coming from your spirit, that is a heart beat from the wind, infinite sound, star, mist, whisper of time…\nAs the Director of Cultural Center <PERSON>, <PERSON> worked in Sololá with a network of indigenous Kaqchikel youth, rescuing pre-hispanic dance and oral traditions, as shown in this video.\nA member of Cultural Center <PERSON> performing indigenous dance. Image from Flickr user <PERSON> used under Creative Commons Attribution-NonCommercial-NoDerivs 2.0 Generic License.\nOpen spaces for art and expression like the cultural center <PERSON> directed are an opportunity for teenagers in extremely poor and marginalized areas to reinvent their identity and revitalize their individual and collective self esteem. It works like a magic solution to discourage youth from getting involved with gangs and drug lords. But as this incident indicates, the spiral of violence is seemingly unstoppable, and it is killing the magic solution by killing the artists.\nThis post is part of our special coverage Indigenous Rights.", "186" ], [ "Guatemala: Indigenous Expressions of Art · Global Voices\nPhoto by <PERSON> and used under Creative Commons license\nOn International Day of the World's Indigenous People, there is a celebration of indigenous peoples and how they express themselves through their artistic creations. These groups, not only in Guatemala, but all across the world often face discrimination, extreme poverty and social marginalization on a daily basis. However, this post seeks to show how indigenous peoples in Guatemala are sharing their artistic expressions.\nComalapa is a special place for indigenous people in Guatemala, famous for their painters and intellectuals respected all over the World:\nTodo comenzó durante los años 30 del siglo pasado, cuando <PERSON> se interesó en el arte de pintar al óleo, y su creatividad le dio la oportunidad de exhibir sus trabajos en Estados Unidos. En aquel país del Norte, <PERSON> consiguió superar el récord de 123 mil visitantes que el pintor y escultor español <PERSON> había registrado en exhibiciones de arte. El éxito que recabó el pintor comalapense a nivel mundial e internacional con sus trabajos primitivistas lo comprometió con su pueblo, por lo que comenzó a enseñarle a las nuevas generaciones. De esa cuenta, surge una segunda generación integrada por 15 pintores primitivistas y en los años 80 nace la tercera; pero esta vez compuesta por nueve mujeres que optaron por el estilo surrealista (pinturas de paisajes con mezcla de primitivismo)\".\nIt all started during the 1930s, when <PERSON> was interested in oil paintings, and his creativity gave him the opportunity to exhibit their works in the United States. In that northern country, <PERSON> broke the record of 123,000 visitors that the painter <PERSON> had registered in his exhibitions. The success of the Comalapan painter worldwide and nationally with his primitivist art committed him with his peoples, so he started teaching future generations.", "398" ], [ "The second generation were 15 painters, the third generation included women, and they changed their primitivist style for a surrealist style (a mix of landscapes and primitivism).\nHere is a link to Naiftenango [es], a collective blog devoted to the “Naïf or primitivist art” in Guatemala, where the team filmed a short video on the Curruchiche gallery, led nowadays by his grandaughter, a painter too.\nIt is important to understand that while many indigenous groups share similar problems, there are different groups within Guatemala. Some of them have even been rivals in the past and some do not speak the same language. However, street theater has managed to connect two indigenous communities and brought youth to work together. These groups are supported by \"La Cambalacha \", an organization helping the indigenous communities near Atitlan:\nEl grupo se integra por jóvenes <PERSON> y jóvenes <PERSON>. Estas dos comunidades tienen conflicto entre sí desde hace siglos, por lo que el trabajo conjunto de los y las jóvenes da un valor muy especial al proceso que vivieron durante el montaje de la obra, como también a la presentación de la obra ante las comunidades.\nThe group is formed by Kakchikel youth from San Marcos la Laguna and Tzutujl youth from San Pablo La Laguna. While the two communities have been in conflict for centuries, this is a special effort, because of the time that they shared during the play practices, and also when they performed it for their communities.\nBut perhaps the most impressive, challenging and creative expression of art and identity for indigenous peoples in Guatemala is their clothing. Beautiful handmade blouses are called huipiles that many women still wear. You cannot find two identical pieces, and women express themselves creating new patterns, new styles that tell stories of birds and flowers, like a walking gallery:\nAs <PERSON> [es] points out:\nDetengámonos y contemplemos los pequeños e innumerables detalles de la indumentaria indigena, probablemente expanda nuestra visión.", "398" ], [ "Guatemala: June 30th, A Day to Remember · Global Voices\nPhoto taken by <PERSON> and use by permission.\nEvery year on June 30, Guatemalans celebrate a festive day, when the Guatemalan Army goes on a parade in the city's center. This year was exceptional because bloggers were the real reporters of the event, and experienced something unusual that happened.\nWhy is there a celebration on June 30? in Guatemala Blog [ES] you can find the answer:\nEl presidente <PERSON>, en el año de 1965, en conmemoración de <PERSON>, siendo su fundador, establece el 30 de junio como el Día del Ejército.\nIn 1965, President <PERSON> commemorated the achievements of former President <PERSON>, who founded the Guatemalan Army, by establishing June 30 as Day of the Army.\nOpinions are as diverse as bloggers. One day before the parade, blogger <PERSON> [ES] in an extensive critique of the armed forces on his post “En la víspera” delcared:\nYo no me quedare de brazos cruzados ire de parte del pueblo, con el pueblo y por el pueblo por medio de una marcha de protesta que habra ese dia a manifestar mi repudio a dicha institución\nI will not stand with my arms crossed. I will go the protest representing the people, with the people, and for the people to voice my dissent towards such an institution.\nAnd next day, <PERSON>, the Parade and the protest took place organized by H.I.J.O.S, an association of Sons and Daughters for Identity and Justice Against Silence, whose members are relatives of those who suffered the loss of a family member during the armed conflict in Guatemala.", "186" ], [ "But many things happened at the parade and protest. Sometimes a picture says more than hundred words, as journalist and blogger <PERSON> shows on his blog.\nHis photo report´s title is “The March for Remembrance Halts Military Parade” There you can see the events unfolding step-by-step with some accompanying explanations. The picture on this post is part of it, and he kindly provided authorization to use it.\nHowever, in rural Coban, the festivities were quite different as you can see in the pictures by Blog Verapaces [ES].\nCon un tradicional desfile y la participación de bandas colegiales y seguramente algunas actividades especiales, el Ejercito celebró su día en la ciudad de Cobán.\nWith a traditional parade and the participation of school music bands, and some special activities, the Army celebrated the day in the city of Coban.\nGuatemala is a small country with huge contrasts, different views, but short coverage by the press. Things that really matter are now shown by bloggers, in an open way.", "186" ], [ "Guatemala: Experiences in Birdwatching · Global Voices\nPhoto by Bob MacInnes and used under a Creative Commons license\nBirdwatching is gaining popularity in Guatemala and is attracting many visitors from around the world. These birdwatchers are usually very excited to find a variety of birds located in beautiful sceneries. The number of species of birds located in the Guatemalan avifauna is more than 700. Many of these enthusiasts have started to write about their experiences through the use of blogs.\nThe blog Birdwatching Guatemala explains why Guatemala is so attractive to nature lovers :\nBiological diversity has enabled Guatemala to stand among the 25 countries with the most variety of natural resources in the world. Millions of species living in its varied ecosystems, more than 700 species of birds, mammals like the jaguar, tapir and a variety of reptiles and insects.\nJeff Bouton of the Leica Birding Blog was pleased with his discoveries and with his time spent in Guatemala during a birdwatching expedition in the department of Petén“\nWe spent a glorious morning birding the Cerro Cahuí reserve in Peten, Guatemala. It was a wonderful place and we enjoyed views of tropical specialties like Red-throated Ant-Tanagers, Gray-headed Tanagers, Royal Flycatchers, Sepia-capped Flycatchers, and Golden-crowned Warblers, occurring side-by-side with more familiar neotropical migrants like Magnolia, Worm-eating, & Kentucky Warblers, and Yellow-bellied & Great Crested Flycatchers. At one point we ran into an amazing feeding flock and we were picking out new birds left and right.\nRob Fergus, also known as “The Birdchaser” tells the story of Santiago, a small village located near Lake Atitlán, where he was able to see and learn about area birds:\nThe Tz'utujil Mayan town of Santiago Atitlan on the shores of Lake Atitlan is known in Tz'utujil as the “House of Birds.” We asked a lot of folks why it has that name, and were told that birds used to be abundant there, nesting in the rooftops of thatched houses. Most of the people we were able to talk to there are not as closely tied to the forest or fields as their predecessors, so we weren't able to get as many bird names or stories as we did in the Mopan or Q'eqchi’ areas, but we still collected some interesting accounts of using hummingbirds as cures for epilepsy and as love potions!\nAnother birdwatcher, Bill Thompson, III writes in his blog called Bill of the Birds about how he spent his birthday in Guatemala and about the present he received from Mother Nature, when he was able to see one of the most rarest birds:\nOne of the highlights from early 2008 was my birthday bat falcon in Flores, Guatemala. The bat falcon is a fairly common raptor in the tropics. In fact it was something of a sore point for me that I had not seen one after more than half a dozen trips to its range in Central America.", "398" ], [ "I'd gotten amazing looks at a larger (and much rarer) relative, the orange-breasted falcon on two different trips to Tikal, but the bat falcon had eluded me.\nBirdwatching is not only a hobby, but also a crucial activity to preserve the species, as explained by Dear Kitty :\nInvited by the Foundation for Anthropological Research and Environmental Studies (FARES), a Guatemalan archaeological research organization, the Cornell ornithologists recorded 184 bird species. The reserve holds one of the largest intact tropical forests in Central America as well as key Mayan archaeological sites at El Mirador and Tintal , where the Cornell researchers focused their surveys. The bird count may help with long-term biodiversity conservation plans at the reserve.\nPhoto by Arturo Godoy and used under a Creative Commons license\nIn addition, forest fires and narcoactivity are destroying the habitat where such lovely birds live. Many people, including some bloggers like Arturo Godoy are trying to raise awareness about the fragile habitat. He is spreading the word about a campaign from the National Park El Mirador – Río Azul, which is trying to spread wordabout its cause through its Facebook profile.\nwe're killing the forests of Petén. This year major forest fires are expected during the dry season. We need volunteers, real warriors in this fight for conservation and for life. We need their help in cleaning 44 kilometers of breach and also to spread this information to organizations which may help with equipment and provisions. Please get in touch with Ing. Francisco Asturias: <EMAIL_ADDRESS><PERSON> and used under a Creative Commons license\nBirdwatching is gaining popularity in Guatemala and is attracting many visitors from around the world.", "696" ] ]

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[ [ "It's first important to note that in classical electromagnetism, the $\\mathbf{A}$ and $\\phi$ fields are not physical in the same way that the $\\mathbf{E}$ and $\\mathbf{B}$ are. We can't measure them and they aren't uniquely defined.\nGravitational potential energy is a good analogy. Suppose an object is on a table a height $h$ above the ground. We could say that the object has potential energy $U=mgh$, picking the floor to be $U=0$, or that the object has potential energy $U=0$, picking the table to be where $U=0$. In fact, we could choose the gravitational potential energy to be any $U=mgh+C$ for any $C$, as long as we use the same definition of potential energy in the same problem.\nJust like we can add any constant to the gravitational potential energy, we can add some additional vector field $\\mathbf{V}$ to $\\mathbf{A}$. Let's define the new vector potential $\\mathbf{A'}=\\mathbf{A}+\\mathbf{V}$.", "499" ], [ "By the definition of the vector potential, we know $\\nabla \\times \\mathbf{A'} = \\mathbf{B}$. Using the properties of the curl, we find $\\nabla \\times \\mathbf{A'} = \\nabla \\times \\mathbf{A} + \\nabla \\times \\mathbf{V} = \\mathbf{B}$. However, we know $\\mathbf{B}=\\nabla \\times \\mathbf{A}$, so we can write $\\mathbf{B}+\\nabla \\times \\mathbf{V} = \\mathbf{B}$. Therefore, we see that we can add any $\\mathbf{V}$ such that $\\nabla \\times \\mathbf{V}=\\mathbf{0}$. Because of an identity in vector calculus, we know that any curl-less vector field can be written as the gradient of a scalar field, say $\\psi$.\nWhen we go through the math we find that when we change $\\mathbf{A}$ to $\\mathbf{A'}=\\mathbf{A}+\\nabla\\psi$ we have to change $\\phi$ to $\\phi'=\\phi-\\frac{\\partial \\psi}{\\partial t}$.\nSo we don't have infinite freedom in gauges. We have the freedom to choose any scalar field $\\psi$ and then transform $\\mathbf{A}$ and $\\phi$ as above. The two most popular gauge choices are the Coulomb and Lorenz, which are detailed in the Wikipedia article you linked to in your question.", "418" ], [ "To add to <PERSON>'s answer, I'll give you two scenarios where this equation would be useful. First, notice that this is <PERSON>'s extension of <PERSON>'s law, meaning you can apply it to situations where a magnetic field exists but there is no current (e.g inside a capacitor with an alternating current). Let's first consider the situation where you'd like to find the magnetic field produced by a current carrying wire. We will take the Amperian loop to be a concentric circle around the wire. We know that:\n$$\\oint\\vec{B}\\cdot d\\vec{s}= 2\\pi rB$$\nsince the magnetic field is always parallel to the loop (by the right hand rule), and the path length is $2\\pi r$ where $r$ is the distance from the wire.", "418" ], [ "We also know that:\n$$\\mu_0I+\\mu_0\\epsilon_o\\frac{d\\Phi_e}{dt} = \\mu_0I$$\nsince there is no displacement current in this situation. This allows us to find an equation for the magnitude of $B$:\n$$B=\\frac{\\mu_0I}{2\\pi r}$$\nNow let's consider the case of finding the magnetic field inside a capacitor $(r<R)$ with two circular plates or radius $R$, and with an alternating current in the circuit. Taking the same Amperian loop as before, we also have:\n$$\\oint\\vec{B}\\cdot d\\vec{s}= 2\\pi rB$$\nHowever, in this situation, we have:\n$$\\mu_0I+\\mu_0\\epsilon_o\\frac{d\\Phi_e}{dt} = \\mu_0\\epsilon_o\\frac{d\\Phi_e}{dt}$$\nbecause we know that there is no current through a capacitor.\nIf we take $E=E_0 sin(\\omega t)$ for an alternating current, we know that $\\Phi_E =AE_0 sin(\\omega t)=\\pi r^2 E_0 cos(\\omega t) $ where $A$ is the area of the loop, and $r$ is its radius. Thus, $\\frac{d\\Phi}{dt}=\\omega \\pi r^2 E_o cos(\\omega t)$, giving:\n$$2\\pi rB = \\mu_0\\epsilon_o\\frac{d\\Phi_e}{dt}= \\mu_0\\epsilon_o \\omega \\pi r^2 E_o cos(\\omega t)$$\nand we obtain the final expression for $B$:\n$$B=\\frac{1}{2} \\mu_0 \\epsilon_0 \\omega r E_0 cos(\\omega t)$$\nNotice that in these two cases, the line integral wasn't evaluated mathematically, but rather arguments of symmetry (and a good choice of Amperian loop) were used to reduce it to something easier to work with. Hopefully this gives you an idea of how the Ampere-Maxwell law can be used to find the magnitude of the magnetic field at certain places in different situations.", "628" ], [ "First understand the method of image charges. The idea behind the method is to bypass actually solving the differential equation with boundary conditions, and instead \"cheat\" by guessing the correct solution. To this end, we find a configuration of imaginary charges that together with the real ones will make the potential on all surfaces be what is given.\nIn your case, you have two surface, each with constant potential zero. For a plane, if you have a charge $q$ at $(x,y,z)$ and another one at $(x,-y,z)$, clearly the potential at $y=0$ will be zero.", "586" ], [ "For the sphere, if a charge is at radius $R$ from the sphere with radius $a$, an image charge with charge $-qa/R$ should be placed at radius $a^2/R$, but the same idea remains.\nNow, first add the image charge for the sphere. Now the potential on the sphere is zero, but on the plane, we still have a gradient. However, if you mirror both charges off the plane, you should see that the potential on both the sphere and the plane is zero.\nWriting this all down, we have: $$\\begin{eqnarray} \\phi({\\bf x}) &=& \\frac{q}{\\sqrt{(x-R\\cos\\alpha)^2+(y-R\\sin\\alpha)^2+z^2}} \\ &-& \\frac{q}{\\sqrt{(x-R\\cos\\alpha)^2+(y+R\\sin\\alpha)^2+z^2}} \\ &-&\\frac{qa}{R\\sqrt{(x-(a^2/R)\\cos\\alpha)^2+(y-(a^2/R)\\sin\\alpha)^2+z^2}} \\ &+&\\frac{qa}{R\\sqrt{(x-(a^2/R)\\cos\\alpha)^2+(y+(a^2/R)\\sin\\alpha)^2+z^2}} \\end{eqnarray}$$ Clearly, at $y=0$ we have $\\phi=0$. Now, what about on the hemisphere? points on the hemisphere satisfy $z^2 = a^2 - x^2-y^2$, so that substituting leads us to the potential on the hemisphere:\n$$\\begin{eqnarray} \\phi({\\bf x}_{sphere}) &=& \\frac{q}{\\sqrt{-2xR\\cos\\alpha -2yR\\sin\\alpha + R^2 +a^2}} \\ &-& \\frac{q}{\\sqrt{-2xR\\cos\\alpha +2yR\\sin\\alpha + R^2 +a^2}} \\ &-&\\frac{qa}{R\\sqrt{-2x(a^2/R)\\cos\\alpha -2y(a^2/R)\\sin\\alpha + (a^2/R)^2 + a^2}} \\ &+&\\frac{qa}{R\\sqrt{-2x(a^2/R)\\cos\\alpha +2y(a^2/R)\\sin\\alpha + (a^2/R)^2 + a^2}} \\ &=&0 \\end{eqnarray}$$ By putting the $a/R$ into the square root.\nTo write down the multipole expansion, you just need to write down the <PERSON> expansion of the potential around $1/r$, with $r = \\sqrt{x^2+y^2+z^2}$. This gives that any expression of the form: $$\\lim_{r\\to\\infty}\\frac{1}{\\sqrt{r^2+b}}= \\frac{1}{r} - \\frac{b}{2r^3} + \\frac{3b^2}{8r^5} + \\cdots$$ You can then use this expansion on the components of the potential to get your result.", "521" ], [ "<PERSON>'s law for a current loop being deformed\nI'm working through <PERSON>'s Classical Electrodynamics text (3rd version, chapter 5.15) about <PERSON>'s law:\n<PERSON>'s law is pretty familiar:\n$\\int_c E \\cdot dl = -\\frac{d}{dt}(\\int_s B \\cdot n da)$\nwhich states that the contour integral of the electric field around a bounded surface is equal to the negative time rate of change of the flux bounded by that surface. No problem. Here we have a total derivative and <PERSON> addresses 2 cases.\n\"The flux though the circuit may change because (a) the flux changes with time at a point, or (b) the translation of the circuit changes the location of the boundary\"\nIn either of these cases, it is easy to show that:\n$\\frac{d}{dt}(\\int_s B \\cdot n da) = \\int_s(\\frac{\\partial B}{\\partial t} \\cdot n da) + \\int_c(B \\times v)\\cdot dl$\nby using $\\frac{d}{dt} = \\frac{\\partial}{\\partial t} + v \\cdot \\nabla$ and then applying a \"product rule\", $\\nabla \\cdot B = 0$ and stokes theorem.", "903" ], [ "i.e.:\n$\\frac{d}{dt}\\int_s B \\cdot n da = \\frac{\\partial}{\\partial t}\\int_s B \\cdot n da + (v \\cdot \\nabla) \\int_s B \\cdot n da$\nIn the case where the surface is constant, we can exchange the order of differentiation and integration:\n$\\frac{d}{dt}\\int_s B \\cdot n da = \\int_s \\frac{\\partial}{\\partial t} B \\cdot n da + \\int_s (v \\cdot \\nabla) B \\cdot n da$\nI still have no problem with this. Now we can work on the second term on the right (apply a product rule, drop terms with $\\nabla \\cdot B$ and then apply stokes theorem) to get the $\\int_c(B \\times v)\\cdot dl$ term.\nwhich, when applied to <PERSON>'s law gives the nice result:\n$\\int_c [ E' - (v \\times B)] \\cdot dl = - \\int_s \\frac{\\partial B}{\\partial t} \\cdot n da$\nThe problem arises when you allow the shape of the bounded surface to change. (Consider a circular wire loop in a magnetic field that you then hit with a hammer causing a dent in one side). How does changing the surface influence the result that we derived above? It seems to me that this would prevent us from being able to exchange the order of differentiation and integration which seems like it leaves us in a pretty tight spot ...", "903" ], [ "I feel like a lot of these questions are asking the same thing, so do tell me if I've misinterpreted any.\n1. Is the magnetic dipole picture of assuming a circular loop carrying a current is a kind of \"approximation\"? Or in other words, is the field determined by assuming magnetic fields due to magnetic monopoles different from the original field due to circular loop?\nYes. For example, as you can clearly see in the figure, the two fields don't even point in the same direction in the interior.\nIn short, how accurate is the magnetic field determined by assuming a circular current carrying loop as a magnetic dipole?\nIt gets more accurate the further away you get, because both of them approach the ideal dipole field, $$\\mathbf{B}(\\mathbf{r}) = \\frac{\\mu_0}{4 \\pi} \\left(\\frac{3 \\hat{\\mathbf{r}} (\\mathbf{m} \\cdot \\hat{\\mathbf{r}}) - \\mathbf{m}}{r^3} \\right).$$ More precisely, at large distances, both of these fields differ from the ideal dipole field, in both magnitude and direction, by a fractional amount proportional to $\\ell/r$, where $\\ell$ is a characteristic length scale. For the loop picture, $\\ell = \\sqrt{A}$. For the pole picture, $\\ell = d$.\nAs you go to smaller $r$, the divergences get a lot bigger, e.g. for $r \\lesssim \\ell$ the fields are completely different from the ideal dipole field, and from each other.\n1. Does the pole picture causes variation only in the direction or also includes difference in the magnitude of the field?\nYes.", "780" ], [ "For example, as you can see from the figure, the magnitudes diverge at the poles and at the loop, and there's no corresponding divergence in the other picture.\n1. Where does the pole picture give accurate result for both magnitude and direction of the magnetic field around a circular loop carrying a current?\nAt large $r$.\n1. What are the specifications for the choice of $m$ and $d$? From $md=iA$, the product $md$ is a constant for a particular $i$ and $A$, however, we're free to choose $m$ and $d$ in such a way it satisfies the condition. So does a small value of $d$ (and large value of $m$) give more accurate results, or is it the other way round?\nWhat is exactly true is that in the limit $d \\to 0$ and $A \\to 0$, the two fields approach each other, because they both become the same as the ideal dipole field.\nWhen $A \\neq 0$, it's not clear what value of $d$ gets a more \"accurate\" result, because it depends on how you define \"accuracy\". For example, if you wanted the field at $r = 0$ to be as accurate as possible, then you should send $d \\to \\infty$, because that gets zero field at $r = 0$. But then that would get the field at $r \\approx \\sqrt{A}$ totally wrong. If an IIT JEE problem asks you what the most \"accurate\" result is, this is a vague and undefined criterion and the correct answer is whatever random thing the test writer had in mind at the moment.", "780" ], [ "Electromagnetism problem: where does the magnetic field come from?\nConsider the following problem:\nConsider a plane with uniform charge density $\\sigma$. Above the said plane, there is a system of conducting wires made up of an U-shaped circuit on which a linear conductor of lenght $d$ can slide with constant velocity $v$. The system as a whole has a rectangular shape and is parallel to the plane. (See the picture). Calculate the line integral of the magnetic field $\\bf B$ along the perimeter $L(t)$ of said rectangle as a function of time.\nMy professor solves this problem using <PERSON>'s fourth equation in integral form, assuming that the current density $\\bf {J} $ is everywhere null, and that the electric field $\\bf E$ is the one generated by a uniformly charged plane, i.e.", "903" ], [ "perpendicular to the the plane and of norm $E=\\frac{\\sigma}{2\\epsilon_0}$; thus yielding $$\\oint_{L(t)} {\\bf B}\\cdot dl=\\mu_0\\epsilon_0\\frac{d}{dt}\\int_{S(t)} {\\bf E}\\cdot dS=\\mu_0\\epsilon_0Edv=0.5\\mu_0\\sigma dv$$\nI think there are some things wrong both with this solution:\n1. There should be no magnetic field at all! A uniformly charged plane only produces an electrostatic field. (I know there could be a magnetic field generated by the current inside the wires, but then you couldn't assume that $\\bf J$ is null everywhere as my professor did!)\n2. <PERSON>'s fourth equation does not hold in that form if the domains of integration are allowed to vary with time. In fact, by resorting to the differential forms, we find that plugging ${\\bf J}=\\vec 0$ and $\\frac{\\partial {\\bf E}}{\\partial t}=0$, as my professor assumed, yields $rot{\\bf B}=0$, and thus the line integral of the magnetic field over any closed curve, at any istant, should be zero by <PERSON>' theorem!\nTherefore, my question is the following.\nAre the my professor's assumption ($\\bf J$ $=\\vec 0$, $\\frac{\\partial{\\bf E}}{\\partial t}=\\vec 0$) correct, or do both $\\bf J$ and $\\bf E$ need be modified so as to account for the charges present in the circuit? Is there a current in the circuit at all?", "903" ], [ "One of the deep properties of space that physicists believe to be true is that space is isotropic; that is, in a vacuum one direction is no better than any other.\nIsotropy holds equally well if the system in question is spherically symmetric: as long as there is no way to distinguish one direction from the other, you could not possibly expect the physics to behave in different ways in different directions...\nThis is very good news, because your uniformly charged shell system is spherically symmetric! The charged shell determines a natural origin at the center of the shell, but all directions from this origin are still equivalent, since a spherical shell has no structure that could determine a $``$special$\"$ direction. Thus, at a given radius $r$ from the center of the shell, any physical quantity you may want to determine, including the electric field, must be the same in all directions.\n(One way to formalize this argument is as follows: assume for contradiction that your uniformly charged shell results in an electric field that is not spherically symmetric. Then there must be some radius $r'$ for which $\\vec{E}(r', \\theta_1, \\phi_1) \\neq \\vec{E}(r', \\theta_2, \\phi_2)$; that is, two different directions at the same radius give distinct results. But now rotate the charged shell in space so that $\\theta_1 \\to \\theta_2$ and $\\phi_1 \\to \\phi_2$.", "499" ], [ "Since the charged shell is spherically symmetric, after this rotation nothing will have changed, meaning the electric field at each point in space should be the same as before. But this means that $\\vec{E}(r', \\theta_1, \\phi_1) = \\vec{E}(r', \\theta_2, \\phi_2)$, a contradiction! Thus, the electric field must depend only on $r$.)\nWith this spherical symmetry in hand, we can now apply Gauss's Law. Since the electric field must be the same for all directions, choosing our Gaussian surface to be a sphere with radius $R$ smaller than the radius of the charged shell, we have $$\\unicode{x222F}E\\cdot \\hat{n} dS = 4\\pi R^2E(R) = 0,$$ which of course implies that $E(R) = 0$ for all $R$ enclosed in the uniformly charged shell.\nTo recap, other field configurations are not possible because they would violate spherical symmetry and/or Gauss's Law. Using symmetries to solve problems in physics is a very powerful, but often quite subtle, skill, and one that is worth developing as soon as possible.", "903" ], [ "I feel really bad for the OP getting these downvotes. The question (if worded better) is a really good question. There is obviously a lot of confusion over this - given the range of solutions posted. I think the main confusion comes from two places: (1) using current density in place of current (whether consciously or not), (2) Not realizing that a 1-D vector is a scalar.\nCurrent density:\nFor simplicity, assume we have a conductor with a constant conductance, $\\sigma$. Also for simplicity, let's assume that the electric field is time-independent, but could vary in space. The electric field, $\\vec{E}(\\vec{x})$, is a vector field, that is, at each point in space, we associate a vector space.", "359" ], [ "The relationship between the electric field and the current density in this simplified model is $$\\vec{J}(\\vec{x}) = \\sigma~\\vec{E}(\\vec{x})$$ From this equation, we see that $\\vec{J}(\\vec{x})$, the current density, is also a vector field.\nCurrent:\nThe current is defined with reference to some area as $$I_A = \\int_A \\vec{J}(\\vec{x})\\cdot d\\vec{A}$$ In circuits, the area we care about is the cross-sectional area of the wire. With a DC source the electric field is constant throughout the wire (if AC, still constant spatially but has time dependence), that is $\\vec{E}(\\vec{x}) = E_0~\\hat{z}$ (assuming the wire is along the $z$-axis). This means that the current density is $$\\vec{J} = \\sigma~E_0~\\hat{z}$$ and so the current is (area of interest is the cross-section of the wire, with $d\\vec{A} = dA\\hat{z}$) $$I = \\int dA~\\sigma E_0~\\hat{z}\\cdot\\hat{z} = A\\sigma ~ E_0$$ In this idealized situation, we see that $I$ can be treated as a 1-D vector, so far as the vector space axioms are concerned. We also note that a 1-D vector is a scalar! Note that I am not saying scalar field or vector field.\nLet's see what happens when we aren't confined to a wire and have spatial varying electric fields.\nTake some area through a region in a conductor (with constant $\\sigma$ as before) where the electric field has spatial dependence $\\vec{E}(\\vec{x})$. The current associated with this electric field and area is $$I_A = \\sigma\\int_A \\vec{E}(\\vec{x})\\cdot d\\vec{A}$$ With a little thought, one can see that this doesn't change the argument in our wire case. The current defined this way still produces a 1-D vector, whose direction indicates which way the total flow of positive charges (by convention) is flowing, through the prescribed surface. And again, a 1-D vector IS a scalar.\nNote: in this situation, adding currents is physically identical to adding electric fields (as $\\sigma$ is assumed constant).", "780" ] ]

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[ [ "Fascinating topic! I've been playing with a similar idea myself for a while now.\nDepending on the level of development in your world, you might want to break up the perceptions the \"honest\" culture has of the dishonest one.\nPerhaps socially, the dishonest culture would be viewed negatively by others, maybe making things like tourism and intercultural relationships difficult. However some might view members of the dishonest culture as more desirable mates/partners since they could, in theory, be easier to get along with and/or compete better against rivals.\nIn business, they might be viewed as risky or even treacherous, or they might be sought after as shrewd business partners. Are there lawyers in the culture/world you are making? Would it be fair to assume that they could make excellent legal councelors?\nAs for politics, I think it would depend on where the line is drawn in terms of the kinds of lies told. If it's limited to misdirection or omission of certain details, perhaps they could maintain constructive relations with other cultures. If they also include breaking treaties/oaths/contracts as permissible, I don't really know how that would work out in the absence of coercion.\nThe other point, of course, is how different the other cultures' views on lying are. If it's a culture with a strict moral code or honor system, they might be openly hostile towards people who live outside of their value system. Others might still work with them, but be more distrustful and controlling.\nWhat might serve as an example of the latter is intercultural dynamics in terms of language and communication, specifically: \"burden of communication\" and \"high vs.", "140" ], [ "low context cultures\". Basically, a member of one culture might find himself \"translating\" everything said by someone from the \"dishonest\" culture in order to get to the cold, hard facts.They would then ask very direct questions to follow up. The other person might be aggravated by this if they feel threatened in some way due to the situation.\nOn the flip side, someone from the dishonest culture might have a hard time with an outsider that doesn't understand the subtleties of their communication style, such as catching on to and playing along with a bluff in a high stakes situation.\nI know this is a place to provide answers, but I do have a question that's nagging at me hard. If the culture you're building values prowess in deception, how are the people supposed to evaluate that trait in others if being able to do so means that the deception failed? If the people of that culture are good liars, because that's what they are taught and encouraged to do, I assume they would also be good lie detectors.\nHow would people know that someone successful didn't become so by being honest? Would people just automatically believe that he/she had made it to the top by being an exceptional liar? If it were found out that someone had made it to a position of power in that culture, without the use of deceptions, would that person lose stature, popularity/respect, power?\nAs I said at the beginning, this is a fascinating topic and I'm probably going to lose a lot of sleep thinking about it. Thanks a lot.\nJust for fun, you might want to check out \"The Invention of Lying\". It's a light romcom that sort of goes in the opposite direction of the culture you're building.\n(This is my first post here, so I hope I haven't broken too many rules. My apologies for any damages.)", "620" ], [ "One suggestion might be to use more concrete examples, to give the reader tangible evidence of your ideas. You can use this method in a number of ways.\nOne would be to take an essay (or other piece) you are unsatisfied with and highlight the parts that you feel are too \"wanting-to-be-deep\", which I imagine (could be wrong here) to be a too-cerebral or \"generalized\" approach. For each of these parts, imagine some situation or analogy (from life itself) that illustrates what you mean. These would be separate, possibly unrelated examples of your ideas. Then see if you find a thread between the narratives/ examples that ties any of them together, or select one or two you prefer and see if you can use it/them to connect your abstract thoughts into a more tangible and coherent whole.\nThis sounds more convoluted than it really is! I find this to be a sort of focused brainstorming revision process, and hopefully can help to get your mind connecting less rhetorical and more substantive dots.\nAnother approach could be to scrap the previous draft and consider your idea from the ground up. Think first about the point you are trying to make. But remember to allow your writing to carry you beyond your preconceived notion about what it will be; use your objective as a starting rather than a finishing point. The best writing always surprises the author on some level. So then imagine that original \"point\" you're working on in various scenarios or applications. If what you come up with seems too \"pedestrian\", try to think of something that has emotional as well as cerebral content. Even mathematical concepts can form stories, so try to make connections.\nAlso consider visual or other sensuous illustration. Then, play with it. Try moving parts around.", "487" ], [ "Or try asking questions instead of only declarative/ explanatory sentences. At some point something should \"click.\"\nFinally, think of clichés associated with your idea. See if you can twist or turn them around or make them unexpectedly surreal or different. People often think in clichés without realizing it. When you turn it around, this wakes the reader up, either by being true in an unexpected way or by creating a sense of renewal about the mundane. That's a cheap trick, yes, but oddly it seems to work more than you might think. Of course, here I am not giving you concrete examples...but I'm not sure about the type of essay you're thinking about. Cliché could be common phrases, familiar fables or fairy tales, pop culture references, or something entirely different.\nRemember to avoid dull and expected generalization. All ideas are better presented using examples, metaphors or visual references, etc, something like a virtual power point. Also choose one basic thread or a few examples that can tie together from the examples you came up with. Then if you want to generalize at the end, see if you can find some kind of transformation or \"turning point\", appropriate to your subject. You only have to hint at it, if that's your style. Or be more forceful if that feels right.", "487" ], [ "I apologize in advance because I feel this would be better suited as a comment, but I don't have the requisite reputation.\nI think all the other answers are great, but I just want to add another consideration that I used myself on my last conlang and found really helpful. If you consider semantic domains in vocabulary generation, you'll much more easily avoid remapping English (or whatever your preferred language is). I used to have a PDF that had several dozen semantic domain webs that covered lots of basic vocabulary and prompted more obscure words too, but the link's dead now and for the life of me I can't find a good replacement through some cursory googling. But I'm sure if you do some searching of your own you can find some good basic examples to look at.\nEssentially what this entails is you have a web of related concepts, and different languages will assign different lexemes to different groupings of these concepts. For example, in English we have: cloud, fog, mist, steam, smoke; and without bothering to look up their etymologies, those words all look unrelated.", "312" ], [ "Looking at concept webs like this might help you think about whether you want one word to cover \"cloud\" and \"fog\" but have two different words for steam from boiling water and steam from warm water (such as at a hot spring in the winter).\nI wish I had ready-made semantic domain webs or maps to link you to, but I'm finding it hard to find anything better than generic examples. As a supplemental tool, though, I think it's something that shouldn't be too hard to make on your own in your native language just to use as a jumping-off point for vocab generation. I don't think you'll hit 10,000 words like this, but I can personally attest that it can improve your generation rate significantly for your first several hundred words once your get yourself in the habit of immediately considering all the conceptually related lexemes for each basic word. You might collapse some into one word and add extra distinctions for others. It is kind of mind-boggling how many different words humans employ for things that are barely different. (Of course, if you make a hyper-polysynthetic language, maybe you just need one root per domain!)", "57" ], [ "The order of words tends to have grammatical restrictions that don't allow for you to change this. Everything else however, especially for a first draft, can/should be changed.\nThe idea behind reading aloud is that by hearings one's words read out loud, one notices what sounds good and what doesn't. For me, it takes a few days before I can see these \"errors\" in my writing, so make sure to give it some time, before returning to writing. Here a few, more or less, objective guidelines:\n* Every consecutive sentence should be of different length. This keeps the writing interesting and engaging, and excites the reader because they won't know what comes next.\n* Replacing simple words with more complex ones is good, but don't overdo it; Often, the simplest words are best. If the complex word does not serve any other purpose than to tick off the requirement, replace it with a simpler one.", "487" ], [ "Else, choose the right complex word (e.g. I ran/walked/stampeded/speeded/wandered/trudged to school). Also make sure that you don't use the same complex verbs twice in a paragraph, unless it makes more sense when it's the same (I used the word \"simple\" multiple times to underline the duality of complex vs simple words)\n* That being said, when you have a sentence starting with a conjunctive, do not allow the next few sentences start with one as well.\n* Unless several paragraphs have passed, do not use the same conjunctives (while, although, yet, and, etc.). I am guilty of this myself, and it's tough to go around this sometimes.\n* Use few adverbs (astonishingly, guiltily, happily), and instead say what a character does/scenery is, that makes it astonishing, or guilty or happy. Again, tough, but in my experience, most of my edits are because of this rule.\n* Another way to improve flow is for every sentence to be followed by a sentence that describes what the reader is interested in next. I know you may want to hear an example for this, so I would, for example, dedicate this sentence to giving you one.\nI haven't read your manuscript, so I cannot give you more feedback. But these guidelines take me very far in improving my writing.", "487" ], [ "In short:\nTell the truth.\nWhat do I mean by that? Here's some writing advice from one of my favorite British authors:\nEven in literature and art, no man who bothers about originality will ever be original: whereas if you simply try to tell the truth (without caring twopence how often it has been told before) you will, nine times out of ten, become original without ever having noticed it.\n<PERSON>\nTruth, in this context, is what is true to your characters.\nTry to focus less on making the speech sound \"actually good\", and more on how the speech is going to make the receiving character feel. How are you going to achieve the main character feeling like they suck? If you're going for a serious (not comic) dramatic effect, your ammunition should draw heavily on the flaws of the \"you suck speech\" recipient.\nTake your <PERSON> quote, for example. The reason this quote is a joy to read is because 1) it's true to the characters (<PERSON>'s existence / the testing facility is built on making up facts to influence the test subjects) and 2) it contains a stab of truth: the test subject is, in all likelihood, a clone who doesn't even have a mother.*\nThe quote is untrue (which is why it's funny) and true (which is why it's sad).", "873" ], [ "<PERSON> constructed the \"you suck speech\" with the aim of discouraging the test subject, and the writers constructed the speech to be comical.\nEDIT: I'll echo <PERSON>'s answer, that the ranter, to be true to their character, could rant about what bothers them most about the other character. I'd also add that while the ranter may be annoyed and want to vent, their motives could lie elsewhere. Going back to your example, <PERSON> is probably annoyed that the test subject is misbehaving, but she's making up the \"horrible\" test results in order to influence the test subject.\nThis just makes the point that there can be many different kinds of \"you suck\" speeches and they'll have varying degrees of venting, discouraging, distraction, etc.\n*Please forgive my limited knowledge of the Portal universe--if the test subject has parents, correct me.", "494" ], [ "Note: if this answer is too long, you can skip to the main conclusion section below.\nWe can explore what sort of robots we would need by looking at the absolutely critical factors that children need to grow into mature adults with the core behaviours you mentioned, and whether/how robots can facilitate the same.\nThere is no magic bullet to this: no collection of robots can absolutely raise a perfect group of children. There are genetic, congenital and even accidental factors involved that can strongly impact lifetime development that you can't necessarily weed out completely. Nor can you expect a thoroughly perfect answer: children's development is still very much an active research area, and there are few certainties in this regard.\nAssuming only that a select group of children are introduced into this artificial environment that meet a minimum bar (no damage, no genetic diseases, etc.), then we can proceed on that assumption to flesh out what factors are needed to provide future care.\nWhat I'm Going to Ignore: For the purposes of this question, we will assume a certain level of common sense e.g. that actively dangerous substances or materials are prohibited in the child rearing environment, that it meets a minimum standard of human care (e.g. no extreme sensory deprivation, it is light, not too hot, not too cold, etc.), and that some care is taken for granted (i.e. age-appropriate consumption and regular diaper changing are enforced, but everything else is not guaranteed).\nAll we want is to know what the bare minimum an active agent needs to provide to stimulate the relevant skills - in other words, we will also ignore needless frills that encourage faster development but are not required to stimulate the necessary skills, like, say, making them listen to <PERSON> at an early age.\nSensory Stimulation\ntl;dr Robots need to have human-like skin but don't have to look human, though it is best if they do.\nThere is some evidence that suggests that sensory stimulation between mother and child between an active agent and children plays an important role in infant's long-term social development. Foals exposed to limited maternal contact post-partum experience \"patterns of insecure attachment to their mothers (strong dependence on their mothers, little play) and impaired social competences (social withdrawal, aggressiveness) at all ages. \"\n<PERSON> explored the mother-child bond among rhesus monkeys. Part of his experiments involved rigging up inanimate surrogate mothers (excerpts taken from his Wikipedia page, with points for citation removed except where marked as needed):\n... <PERSON> created inanimate surrogate mothers for the rhesus infants from wire and wood. Each infant became attached to its particular mother, recognizing its unique face and preferring it above all others.[citation needed] <PERSON> next chose to investigate if the infants had a preference for bare-wire mothers or cloth-covered mothers.", "693" ], [ "For this experiment, he presented the infants with a clothed mother and a wire mother under two conditions. In one situation, the wire mother held a bottle with food, and the cloth mother held no food. In the other situation, the cloth mother held the bottle, and the wire mother had nothing.\nOverwhelmingly, the infant macaques preferred spending their time clinging to the cloth mother. Even when only the wire mother could provide nourishment, the monkeys visited her only to feed. <PERSON> concluded that there was much more to the mother-infant relationship than milk, and that this \"contact comfort\" was essential to the psychological development and health of infant monkeys and children. It was this research that gave strong, empirical support to <PERSON>'s assertions on the importance of love and mother-child interaction.[citation needed]\nSuccessive experiments concluded that infants used the surrogate as a base for exploration, and a source of comfort and protection in novel and even frightening situations. In an experiment called the \"open-field test,\" an infant was placed in a novel environment with novel objects. When the infant’s surrogate mother was present, it clung to her, but then began venturing off to explore. If frightened, the infant ran back to the surrogate mother and clung to her for a time before venturing out again. Without the surrogate mother's presence, the monkeys were paralyzed with fear, huddling in a ball and sucking their thumbs.\n<PERSON> later experiments are largely considered unethical (he subjected rhesus infants to extreme long-term sensory deprivation for up to two years, with no light in a confined environment), it would appear that having robots that mimic the sensation of skin are in some ways required for children to be socially well-adjusted later on.\nSuch robots would be best off mimicking the characteristics of maternal skin as much as possible. For example, new mothers' skin is responsive to their babies' temperature.", "362" ], [ "I tried to edit my answer to respond to some comments, but for some reason the edits didn't go through, so here's my response.\nI think what I'm trying to say is that:\n1. Books, or stories in general, represent perspectives. Perspectives can mean a view on an issue, or a perspective can mean how that perspective is communicated. To give a hypothetical example, if two authors write the same book, but only one author knows how to spell, the perspective being communicated in those two books is very different.\n2. There is always stuff to talk about when you're talking about a perspective. Academics wrote an entire book on The Girl with a Dragon Tattoo, even though that's the poster child for \"popular fiction\". Even if you aren't an academic or don't like academic thinking/writing, there is always things to talk about.", "460" ], [ "If you think a book is bad, then you can talk about why you think it's bad!\n3. The question is really what perspectives are useful for you to have more of. Academia (the primary source of what books count as \"literary\", at least in the USA: if a book is added to enough syllabuses in colleges or is taught in enough public schools, etc.) has certain criteria for what perspectives they find useful.\nDo you think that someone who just finished <PERSON>'s Ulysses has gained something more that someone who completed <PERSON> code?\nWell, I would argue that an alien from outer space, who has had no contact with humans, would probably learn more from a book that has resonated with a lot of people and that represents the \"popular\" culture than a book that represents \"elite\" culture. An alien reading Da Vinci Code might not learn very many historical facts, but they would learn something about the value of historical facts to a large portion of the public.\nAnother example: Great Gatsby is a great book if you want to teach high schoolers about symbolism, which is a goal of academia. If you're looking for characters with depth, then <PERSON> is probably not the book for you, unless you're interested in reading something narrated by a detached, boring man with no personality, who is describing a different man with no personality other than the fact that that he is rich and obsessed with a rich woman. But again, let me emphasize, the fact that the characters are boring does not prevent you from learning things from the fact that they are boring. The fact that people ignore the boringness of the characters because they are rich certainly says something.\nWhat you get out of a book depends on you and what you are looking for, not the book.", "460" ], [ "It depends. In cases when the story is not plot-driven, it might even be the desired effect for the twist to be unexpected.\nLets say you are writing a drama novel about the life of a fictional entrepreneur. You go through the significant events that got him here, creating his startup. Finally everything seems to be going smoothly and <PERSON> is just about to fly to SV to pitch his product in front of a crowd of VCs. Funding is the remaining piece of the puzzle and with what he has to offer, success is imminent. Suddenly, he receives a call with terrible news. His six years old daughter is in critical condition after being hit by a car. From there you can end on how he goes to the hospital, she dies, he falls into despair and gives up on everything, including the company that was so far central to the story.\nDid you need to foreshadow the accident? Not really. There is no way the protagonist or anyone in the story's universe could have anticipated it. Accidents just happen without warning. The novel was never about the final resolution of some conflict.", "627" ], [ "It was about the thoughts, feelings and actions of a man experiencing the ups and downs on his journey. The journey just happened to end on a hefty down.\nAnother example is in comedy writing. No one laughs at predictable puns. As long as you set up the right tone, the more bizarre (or even world breaking) a twist is, the more effective it can be.\nOn the other hand, it can be very frustrating if the plot is the driving factor, yet you pull something out of your buttocks in the last moment.\nPicture a murder mystery that ends with a person that was never introduced calling the detective and saying \"Hey, last night I was very drunk. I now notice that I brought a bloodied bat home. I don't remember much of what happened, but I want to to turn in and cooperate.\" Complete disaster.\nOr a classic fantasy story that ends with the benevolent old wizard completing the young protagonist's quest by waving his staff and defeating the evil warlock on the other side of the world (Deus ex machina).\nIt's all about what you want your narrative to revolve around, making that clear to the reader early on and fulfilling said promise. Hence you don't even need to have a twist, as long as you have set up that expectation and there is something else worth while.\nAs for how much to reveal and what the reaction is, I'm going with the assumption that the twist is essential to the story.\n* If you give them all the details and they figure it out well before the ending, they (1) feel a bit bored until they reach it and (2) think the plot wasn't particularly clever (to put it lightly) when they do.\n* If you give them everything needed early on and they don't unravel it, they (1) are filled with a sense of curiosity and speculate along the way and (2) think it was pure genius when it's revealed. Needless to say, it's very hard to accomplish and you run the risk of falling into the first category instead.\n* If you give them most of the information very close to the actual twist, it much depends on the overall tone so far and whether or not said information makes it painfully obvious. Depending on that, you might approach danger territory here or it might just be an exiting new turn.\n* If you feed them bits gradually and the final bit is not disproportional, but simply before the ending - you hit the gold spot. Readers that didn't figure it out will react as if you gave them something from the second category. Readers that did will be engaged along the way and feel rewarded for their efforts once they reach it.", "846" ] ]

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[ [ "Fly-By-Night: Mary & the Witch's Flower Earrings\nIntroduction: Fly-By-Night: Mary & the Witch's Flower Earrings\nAfter watching Mary and the Witch's Flower by Studio Ponoc, I made a pair of Fly-By-Night earrings for a friend as a Christmas gift. I had been planning on making a pair for myself, so that is what today's tutorial is about. These earrings will also have the added cool of glowing in the dark. Plus, even if no one else recognizes these from that movie when I wear them, they still look cute.\nSupplies\n1. Clay in a light bright blue color.\n2. Roller for clay\n3. Clay knife\n4. Clay stylus tool or other pointed tool\n6. Chalk pastels in varying shades of blue (light to dark) and a medium colored purple\n7. Brush to apply pastels\n8. Eye pins\n9. Round nosed pliers (optional; I use them to help me place eye pins)\n10. Wine corks with toothpicks stuck in them (I use these to place the clay on while I color it so I don't mess it up with my hands)\n11. Glow-in-the-Dark paint (I use Deco Art )\n12. Brush for glow-in-the-dark paint\n13. Black Thread\n14. Glue (I use Aleene's Tacky Glue)\n15. Acrylic paint in a blue-purple color (I am using Blueberry Frost by Apple Barrel, NOT the Blue Bonnet color shown here)\n16.", "95" ], [ "Varnish (optional for polymer clay)\n17. Earring hooks\nStep 1: Basic Form\nSimple enough: roll out two balls from the clay in the *same* size.\n*Or as close as you can :)\nSet these aside.\nStep 2: Calyx\nThe leafy piece on the bottom of a flower where the stem is is called the calyx.\nRoll out your clay thinly. Cut out a six point star shape to cover the bottom of the flower. I use the stylus to draw them before I cut them out.\nStep 3: Star Shapes\nWith the rest of the blue clay, roll the clay out thin.\nWith the stylus tool, trace two little star shapes on the clay. These star shapes should have rounded edges instead of traditional pointy edges. They should be small enough to sit on the little balls and look like bloom ends (like a blueberry. These really look like glowing blueberries.)\nCut these stars out carefully with the knife. You will probably have to smooth them out a bit and redefine the shape after you cut them out, but that is fine.\nPlace the star shapes on top of the blooms on the opposite end of the calyx. Press the stylus tool into the center of the star shapes, affixing them to the round clay.\nStep 4: Eye Pins\nPut an eyepin through the bottom of the bloom, through the calyx. I use my pliers to make sure I get the pin where I want it.\nIf you have eye pins you bought from the store, you may have to trim them to the right size. You want the pin to not go any farther than halfway through the flower. Also, remember to bend a zigzag shape into the bottom of the pin. This will prevent the eye pin from falling or being pulled out.\nIf you want to know specifically how I do this, or you want to learn about making your own eye pins, this tutorial will help you:\nJewelry Basics: DIY Eye Pins for Clay Charms\nStep 5: Handy Tools\nNow you have two little fly-by-night blooms.\nGrab the toothpick/cork tools and place the blooms on the toothpicks. Put the toothpick in the hole in the center of the stars. Don't shove them on to the toothpicks, just enough that they will stay put and not fall off while you are coloring them.\nStep 6: Color\nNow it is time to color the flowers.\nSince I know it is hard to see what colors I am putting where in the photos, I have made a chart to try to explain what colors I have and where they go. Of course, how you want to color it is open to interpretation because I am just trying to imitate what was in the movie. If you see it differently, color it differently.\n*Don't color the calyx and rounded star portion. If you get color on them, no harm done, but we are going to be painting them later.\nThe fly-by-nights in the movie seem to glow from inside, but they have deep purple centers. So I am going to start with purple.", "987" ], [ "Howl's Moving Castle Earrings- Studio Ghibli\nIntroduction: Howl's Moving Castle Earrings- Studio Ghibli\nHowl's Moving Castle is one of my favorite Studio Ghibli movies. I find it inspiring.\nOne of the most sought-after pieces of Studio Ghibli jewelry is Howl's jewelry set. They sparkle like magic and are pretty pieces in themselves without having belonged to a handsome wizard. Today I am going to show you how to make your own Howl's Moving Castle earrings. I will be publishing Instructables on the necklace and ring as well.\nSupplies\nEarrings:\n1. Clay in green\n2. Eyepins\n3. Gold hook earrings\n4. Two small glass red seed beads\n5. Wire in 24 gauge\n6. Pliers\n7. Green pastel\n8. Knife or toothpick to scrape and mix pastel\n9. Soft brush\n10. Triple Thick (or TLS for polymer clay)\nStep 1: Sculpt Teardrop Shapes\nWith the green clay, roll it between your fingers, making one end smaller than the other, to make a teardrop shape. Insert an eye pin at the top of the tear drop. Make two. They should be about as long as a quarter is from side to side.", "95" ], [ "Bake or leave to dry.\nStep 2: Adding Red Gems\nGet out the gold earring hooks, piece of wire, and the glass red seed bead. With the round nosed pliers, curl one end of the wire piece into a loop. Slide the red bead onto the wire. The loop will stop it from coming off at the end.\nTake the round nosed pliers and curl a second loop on top. You will probably have to remove your pliers and pinch it closed. Now the bead should be trapped by the two loops.\nOpen the loop on the earring hook by twisting the loop sideways where it meets. Don't pull it open. Slide on of the loops on the piece of wire onto the loop on the hook, then twist the hook closed, trapping the bead's wire loop on the hook. Do the same for both pieces.\n*If you had gold wire it would be more accurate, but I didn't have any, so I had to go with silver.\nStep 3: Attach Earrings\nGet out the dried/baked tear drop shapes. Open the loop on the eye pin on the tear drop shape. Hook it to the end loop on the bead wire, making it hang from the bottom. Close the eye pin loop.\nStep 4: Triple Thick Varnishing\nTo give them a bit of a luminescent appearance, I will be varnishing them with Triple Thick mixed with green pastel. I chose a darker shade of green pastel so that they could look like they \"glowed\" from within.\nScrap off the pastel stick into a powder. Mix this powder with a bit of Triple Thick varnish. Continue mixing until you get an even color.\nWith a brush, apply the colored Triple Thick to the teardrop shapes. Be careful not to overwork it; you can go back and add another coat later, but if you keep brushing what you have applied it will become lumpy.\nI applied three coats in total.\nStep 5: The Earrings of <PERSON>\nAnd there you have it! You have these magical earrings. You can sport your Studio Ghibli style without screaming, \"I love Studio Ghibli!\" (even if you might want to). These earrings can be worn to formal events without standing out as fan jewelry and still being pretty.\nI have another Studio Ghibli tutorial already published here. I am working on more Instructables about <PERSON>'s jewelry.\nGo clay today!", "902" ], [ "\"Magic\" Studio Ghibli Earrings\nIntroduction: \"Magic\" Studio Ghibli Earrings\nIn the Studio Ghibli movies, there is a set of earrings (or very similar earrings) that are worn by various characters, most of which are magic types. Characters who are seen wearing these are <PERSON>'s mother, <PERSON> (<PERSON>'s Delivery Service) <PERSON> (<PERSON>'s Moving Castle), <PERSON>'s mom, <PERSON> (<PERSON>), and <PERSON> ( <PERSON> of The Valley of the Wind). The earrings are a red, teardrop dangle. I don't know if there is any specific connection, but I noticed it was a common theme.\nIf you want a subtle way to sport your love of Studio Ghibli movies, these earrings may magically give you the answer!\nI will show two different ways to make these earrings.\nSupplies\nVersion 1: With Glass\n1. Two glass teardrop pendants in red\n2. Round nosed pliers\n3. Copper wire in 24 gage (or bigger, depending on preference, I want mine to be practically invisible).\n4. Gold earring hooks\nVersion 2: With Clay\n1. Clay in red (or you can paint it) *polymer clay or air dry\n2. Eye pin\n3. Various clay tools (if needed), I recommend a roller and stylus tool, but I'm not actually going to use any tools.\n3. Varnish OR TLS, depending on if using air dry or polymer clay\n4. Soft pastel in red\n5. Toothpick or other tool for scraping off and mixing pastel\n6. Soft brush\n7.", "95" ], [ "Gold earring hooks or post earrings for diy earrings\n8. Pliers\nStep 1: V1: With Glass\nFirst, grip the end of the copper wire at the very base of your round nosed pliers. Wrap the wire twice around the base, then move the wrapped wire a bit up the plier nose and wrap again. Keep moving the wire upward while wrapping until you have a small spiral when you pull the wire off.\nPull the spiral off and grip it with the pliers. The wire that comes from the center should be bent upwards so the spiral forms a little foot or base.\nStep 2: Add the Bead\nMeasure your wire by holding the glass bead next to the wire.The spiral will be at the bottom of the bead . Cut the wire with excess for making an eye loop.\nSlide the glass teardrop bead on the wire.\nGrip the wire that comes from the top of the bead, pulling until the spiral is snug against the base of the bead. With the pliers, bend the wire to a horizontal position. Wrap the wire around the plier to make a small loop.\nWrap the excess wire around the base of this loop until all the wire is used (you can tuck the tail inside the bead if you prefer).\nDo this step for both beads.\nStep 3: Add Earring Hooks\nAdd earring hooks by twisting the loop on the earrings sideways to open the loop (don't wrench it open). Slide the copper wire loop onto the gold loop and then close the gold loop.\nYou are finished!\nStep 4: V2: With Clay\nTake a ball of red clay and shape it into a teardrop shape by rolling it and pinching it with your finger. It should be about as long as an American quarter is wide.\nPoke the eyepin into the top of the tear shape.\nMake two.\nLet the clay dry or bake as your clay instructs.\nStep 5: Add Earring Hooks\nOpen the earring loop by twisting it sideways with the pliers. Don't pull the loop open; twist it.\nAdd the pendant and then close the loop by twisting it back to its original position.\nStep 6: Colored Varnish\nI get a little bit of the Triple Thick on a container lid and then scrape pastel onto the varnish. I mix the pastel dust thoroughly with the varnish so there are no flecks of pastel dust.\nThen just apply it with a soft brush. I do several coats to try to give it a bit of a \"glass\" appearance. Let it dry for a day at least between coats, otherwise it will remain tacky.\nIf you like, you can mix up a good amount of this colored varnish and store it in a small airtight jar so that you can quickly swipe another coat on without having to mix the pastel every time. That is what I am going to do so that it saves me time!\nStep 7: Finished!", "902" ], [ "Sunshine Rainbow Arch Clay Earrings\nIntroduction: Sunshine Rainbow Arch Clay Earrings\nThe arch polymer clay earrings are really trendy, and this design stands out more than your average polymer clay earring. A cute sunshine smiles above a bright rainbow arch to remind you that happy days are just around the corner. I will show you how to make these without using cutters, so don't feel intimidated or pass it by if you don't have any polymer clay cutters!\nSupplies\n1. Clay (polymer or air dry, your choice) in Red, Orange, Yellow, Green, Blue, and Violet.\n2. Clay in Black\n3. A work surface (I am using an acrylic board)\n4. Round Nose Pliers\n5. Two Jump Rings\n6. Two Flatback Stud/Post Earrings\n7. Two flat surfaces (I am using both my workspace acrylic board and a second identical board. You can use your work surface for one flat surface and whatever else for your other flat surface. Just make sure it isn't something that will stick to your clay and can be easily held in your hand. The next step will explain this better so you can know what you need).\n8. Clay Roller tool\n9. Clay Knife tool\n10. Ball tool\n11. Clay Stylus tool (or a tooth pick)\n12. Varnish (optional; I am using Duraclear Polyurethane Varnish in Gloss).\n13.", "95" ], [ "Brush to apply varnish\nStep 1: Rolling Out Clay the Easy Way\nThis is a really easy way to roll out logs of clay. You need two flat surfaces (I am using two small acrylic boards) and your clay.\nPut the piece of clay on your flat surface (first board) and then lay the top board on top of the clay, pressing slightly while moving the top board back and forth. The clay will become a smooth log! How even it is depends on how good you are at pressing evenly on the top board, but it is easy to apply more pressure to one side and even out a lopsided log. I first saw this done by Kaylana Design Tutorials and have since seen other polymer clay artists do this. It really makes rolling logs so easy!\nI included a gif that hopefully works, but if not I included photos as well.\nStep 2: Make the Arch\nStarting with the violet clay, I roll out a thin log of clay in the way I showed in the first step. If you don't want to do that, obviously you can just roll out the logs with your fingers.\nMy clay log is about the thickness of a standard round toothpick.\nWith the violet clay, I bend it into an arch or upside down \"u\" shape with my fingers. This is the start of the arch, so don't make it huge. Mine is a skinny arch.\nSet that aside and move on to the blue clay. Roll it out into a toothpick sized snake, then take your violet arch and carefully wrap the blue log around the violet arch. Make sure the two colors are touching so they bond to each other. Don't worry about loose ends right now; we'll deal with that later. You should now have an arch with a violet middle and blue outside.\nProceed to do the rest of the colors the same way in this order: green, yellow, orange, and lastly red. I didn't include photos of me rolling all the separate colors out because that would get exceedingly boring.\nOnce the red as been wrapped on top of the orange arch, you should have a rainbow arch! Now with the knife tool we will trim the ends even with one another. My arch measures about an inch and an eighth (1 1/8th inches) from the trimmed bottom to the tip of the arch, but you can make it as short or tall as you like. The ruler will come in handy for making sure your second arch is the height of your first arch, or you can just lay the first arch on top of the second one and then trim it evenly.\nWith the stylus tool or toothpick, poke a hole in the top of the arch in between the red and orange layers. This is the jump ring hole.\nMake the second arch in the same way you made the first.\nStep 3: Make the Sunshine\nWith the yellow clay, roll out the clay into a flat sheet. Don't make it too thin. With your stylus tool or your knife tool, draw a small circle on the yellow clay and then cut it out with the knife tool.\n*If you are worried about not being able to make a good circle, lightly press the top of a nail polish bottle onto the clay so it makes a circle you can trace around.\nSet the yellow circle aside.\nRoll out the yellow clay again. This time place the little circle on the rolled out clay.", "994" ], [ "Pie Charms From Clay: Earrings, Necklace, Etc.\nIntroduction: Pie Charms From Clay: Earrings, Necklace, Etc.\nI have never attempted to make pies from clay until now, even though people are always encouraging me to make food themed jewelry. I have made little jams, little ice cream cones, little strawberries, and recently made these skillets with bacon and eggs earrings, but that was about the extent of my food jewelry. With pi day coming up, and pies on my brain, I decided to make some pie themed jewelry. (We actually went a little nuts at my house and made eight edible pies, but that is a whole 'nother story.)\nSince I know that there are tons of pie favorites, I decided to try to make several different types so people could make what they themselves like. Feel free to skip to the pie of your choice; I will have them listed in the Supplies list.\nThese are just charms, so they can be used for earrings, keychains, whatever.\nSupplies\nI have listed the supplies that are specific to each pie under their own section, not here.\nHere are the basic supplies for making all the pies.\n- Clay in a dough color (polymer or air dry)\n- Chalk pastels in light brown, dark brown, orange, yellow, and rust red\n- Brush for applying chalk pastels\n- Clay tools (roller, ball tool, stylus, knife - my favorites can be found here )\n- Work space\n- Liquid Clay (for polymer) or DecoArt Triple Thick (for air dry)\n- Toothpick or pin\n- Surface to mix liquid clay or Triple Thick on (I am using small plastic lids, not pictured)\n- Kitchen Sponge\n- Varnish (I use Duraclear Polyurethane, it is available in gloss, satin, matte, and ultra matte)\n- Brush for Varnish\n- Eye pins\n- Round-nosed pliers (I use them to help put in the eye pins - mine are Cousin 3-in-1 pliers )\nFor Pie Pans:\nYou can use a bottle cap for a pie pan instead, or you can use clay. If you use clay, you don't have to have these specific colors; you can paint the clay your desired color, as I do. Feel free to use copper, black, or whatever color for your pans. I am making metal and ceramic pans here.\n- Clay in white (or white paint, I am using Folk Art Titanium White)\n- Clay in silver (or silver paint, I am using DecoArt EXTREME SHEEN Tin)\n- Knife tool\n- Nail polish bottle top\n- Small ball tool (for ceramic dish)\n- Brush (if using paint)\n- Varnish (see above)\n- Brush for Varnish\nI decided it would be silly to repeat myself on making the crust for every pie, so for the Bottom Crust go to STEP 2 (all pies will need this).", "95" ], [ "If you want a Top Crust, go to STEP 3. For a Lattice Crust go to STEP 4.\n*Pies that commonly use a top crust: Apple, cherry, any type of berry pie.\n*Pies that commonly use a lattice top: Cherry, blueberry, blackberry and other berry pies\nStep 1: Pie Pans\nStep 2: BOTTOM CRUST FOR ALL PIES\nStep 3: TOP CRUST\nStep 4: LATTICE CRUST\nStep 5: Apple Pie\nStep 7: Cherry Pie\nStep 9: Coconut Meringue Pie\nStep 10: Pumpkin Pie\nStep 11: Blueberry Pie\nStep 1: Making Pie Pans\nYou can skip this step if you want to use a bottle cap. I wanted my pies to be smaller than that, though, so I am making my own.\nRoll out any color clay thinly, but not super thin. Your pan will need a bit of an edge.\nPlace the clay on top of the nail polish bottle and carefully press it around the edge. With the knife, cut the clay a little bit from the top of the bottle in as straight of a line as you can. Take off the excess clay.\nRemove the clay from the top of the bottle. This is the pie pan.\nAttach an eye pin by pushing it through the side. You can stick a small ball of clay on the end inside the pie pan to give it a firm hold if you wish ( pie filling will go on it anyway, so that will give it something to stick to if you want to skip this step).\nWith your fingers, gently pull/push the rim of the pan outwards from the top, making it have a slight slope.", "69" ], [ "Master Sword Trinket Dish (Polymer Clay)\nIntroduction: Master Sword Trinket Dish (Polymer Clay)\nI've been seeing a lot of polymer clay trinket dishes lately on my Instagram feed and wanted to make my own. I happened to get a Hylian shield ring in a random cheap jewelry grab bag, and it was the main inspiration for this project. I also happened to be consuming a lot of miniature diorama content lately and wanted to make my own twist on it by turning miniatures into functional home-good items (a bit like a closet-cosplay to their hundreds-of-hours-thousands-of-dollars works of art).\nSupplies\nMaterials:\n* Polymer Clay (here I use Super Sculpey and Papas Clay in a blue and purple mix)\n* Bake and Bond (liquid polymer clay adhesive)\n* Acrylic Paint (in black, white, teal, metallic gold and silver, and various shades of gray and green)\n* Matte and Gloss varnishes (I used varathane water-based polyurethane, but you can check out The Blue Bottle Tree's guide for options if that is not accessible)\nOptional (if you want to add flowers)\n* White, Green, Yellow, and Teal Polymer Clay\n* Thin jewelry wire orflorist wire\n* Wire cutters/Pliers\n* Liquid polymer clay\n* Glow powder\n* Aqua/Teal pigment powder, iridescent shimmer pigment powder\n* (the liquid clay, glow powder, and pigment powders can be substituted with acrylic paint, which is probably more accessible)\nTools:\n* Needle Tool\n* Silicone shaping tool\n* Craft Knife\n* Paintbrush\n* Sponge\n* Cardstock and Paper to make templates\n* Oven\n* Electric sanding tool (such as a nail art file)\n* Modeling Clay (Optional.", "95" ], [ "This is used to make a mockup)\nStep 1: Before You Begin\n* Prepare your clay by conditioning it (knead it until it is soft and workable)\n* Create a mock-up to check that the sword is small enough to fit rings over.\nHere I use Sculpture Pro wax-based clay (similar to Monster Clay) for the mock-up because it is malleable yet stays firm and holds its shape so it can be picked up to test adding rings through it. From this, I would know what size to make a paper template for the Master Sword. Mine ended up being 2 cm across at the largest part of the hilt, and a bit over 0.5 cm for the majority of the rest of the sword).\nYou can also make your mock-up from cardstock to test if rings are able to fit past the sword guards.\nStep 2: Create Templates\n* For the trinket dish, cut out an equilateral triangle the size of how large you want the trinket dish to be from cardstock.\n* Create a template for a smaller equilateral triangle as the pedestal to hold the sword.\n* Trace an image of the Master Sword onto paper. I made mine by zooming in on an image of the sword to match the size of my mock-up on a tablet, then used the tablet as a light table to copy it onto paper.\nStep 3: Master Sword: Shaping\n* Roll out a thick sheet of blue-purple clay\n* Use the sword template to cut out the shape of the Master Sword\n* Thin out the edges of the blade by flattening them, trimming the excess clay back to the template's size\n* Round out the sides of the grip\nStep 4: Master Sword: Carving Details\n* Following a reference image, use the needle tool to indent the details of the sword.\n* Use the silicone sculpting tool to shape and deepen the details on the hilt\n* If there isn't enough clay to sculpt in some areas, add and blend small amounts of clay shaped similarly to the detail they are filling in (I did this by adding thin snakes of clay to the top parts of the wings on the guards, the details in the pommel, and the diamond shape on the hilt)\nOnce you are satisfied with this half of the sword, bake the clay following the directions of your clay packaging.", "987" ], [ "Skillet of Bacon 'n' Eggs Earrings\nIntroduction: Skillet of Bacon 'n' Eggs Earrings\nWake up in the morning and put on a pair of skillet eggs 'n' bacon earrings to greet the day! Novelty earrings are the rage, and these will definitely catch people's attention. You can make them yourself and then people will notice them even more because of how radiant you will be while you wear them.\n*In this Instructable I have tried to include polymer clay instructions and air dry clay instructions. I will have polymer clay steps marked with an asterisk and in bold.\nSupplies\n1. Clay (air dry or polymer clay) in black or grey, white, yellow, and translucent\n2. Clay tools (roller, stylus, knife, workspace)\n3. Small round cutter (optional)\n4. Nail polish bottle with a smooth top\n5. Eye pin\n6. Acrylic paint in sequin black or iron black (if you are making a cast iron skillet, OPTIONAL)\n7. Small brush\n8. Soft pastels in rust red, brown, orange (or you can use diluted acrylic paint in the same colors)\n9. Gloss Varnish (I use Duraclear Polyurethane ) *OR Liquid Clay\n10. A toothpick or pin\n11. Earring hooks\n12. Round-nosed pliers\nStep 1: Skillet Base\nThe first step is the skillet.\nCondition the clay by kneading it in your hands and rolling it out several times with the clay roller. Once the clay is pliable, roll out the clay thinly, but not so thin that it wants to tear. This will be the frying surface of the skillet.\nWith the round cutters or with your knife, cut out a circle that is bigger in diameter than the top of the nail polish bottle.", "95" ], [ "(I placed my nail polish bottle upside down on the clay so that I could make a pretty even circle by tracing around it with the knife.)\nCenter the circle over the top of the nail polish bottle and press it down around the top. Leaving a bit for the skillet's rim, trim around the top of the nail polish bottle so that you have a little flat bowl shape with nice smooth edges.\n*POLYMER CLAY: You can preassemble the entire skillet and breakfast platter BEFORE baking, or you can bake as you go. I have marked steps where I think baking would be advisable if that is how you choose to do it. If not, just go through all the instructions until you are finished with the project, then bake it.\nStep 2: Skillet Handle\nTake a bit of your black/gray clay and make it flat. Place the eyepin on top of the flate shape and meld the clay over the eyepin. The eye pin inside helps to strengthen the handle of the skillet.\nI roll the clay over the pin to make it cover it. I cut off any excess from the end (because there will be some).\nOnce you have smoothed the clay until there are no visible seams, cut the clay snake just a tiny bit beyond the end of the pin that is inside the clay. Now you have the handle. With a pin, or the stylus, or a toothpick, poke a hole in the handle right where the eye of the pin is. Make it go all the way through so that you can hang the earrings.\nTo attach the handle, place it against the skillet bowl that is on the nail polish bottle and using the stylus or another tool, smooth the two together to form one piece. If you can, make the pin going into the bowl part of the skillet because that will reinforce that join. If you can't, don't worry about it.\nNow the skillet is pretty much finished. Take it off of the nail polish bottle carefully. You will have to kinda press it back into a circle shape after removing it because that will make it slightly warped. Using a tool (your choice), smooth the edges of the skillet bowl so that they are not rough from where you cut the clay.\n*POLYMER CLAY: Pre-bake the skillet for sure if you are planning on painting it. If you want information on how to bake polymer clay, please see <PERSON> over at the Blue Bottle Tree\nOr set aside to dry, depending on your clay type.\nStep 3: Paint the Skillet\nThis step might not be necessary depending on your original clay color or how happy you are with the original color.\nAfter the skillet has dried or been baked, paint it with the acrylic paint. I wanted to paint mine because I have this color called \"Sequin Black\" or something like that, and it reminds me of the way cast iron kinda glistens.\nStep 4: Egg Base\nOn to the egg (p.s: I hate eggs).", "95" ], [ "Beginner Jewelry: Wooden Photo Earrings\nIntroduction: Beginner Jewelry: Wooden Photo Earrings\nThese are actually some of the first pieces I ever made when I started getting interested in making jewelry. I wanted some fan girl jewelry and couldn't afford to just go buy something, so I needed to make it myself. At the time I was in luck because I had a wooden necklace that had broken and was irreparable, but I had kept the wood pieces, and these became my base.\nSince I was able to do it as a beginner, I think that these wooden photo earrings are definitely a project that the jewelry artist who is just starting out will benefit from. Even those of us who have been making jewelry for a while could get some joy out of earrings with photos of our choice on them.\nI am using my own photos for this Instructable. You can use whatever you like, just please keep in mind that if you sell earrings like this your photos will need to be your own.\nSupplies\n1. Wood pieces: you can use scrap pieces you have or buy some premade. I'll talk more about this is the second step.\n2. Electric drill\n3. Small drill bit: mine is a #55 with a 118 degree point\n4. Sandpaper, fine grit (you may decide you don't need this)\n5. Photos or drawings (not pictured)\n6. A computer or laptop with a word document program (not pictured)\n7. A printer with colored ink (if your photo is colored). Mine is an inkjet. (not pictured)\n8. Regular white copy paper\n9. Scissors\n10. Pen or pencil\n11. Mod Podge or Polyurethane Varnish or some other sealer\n12. Brush\n13.", "95" ], [ "A pin (you don't have to have it)\n14. Round-nose pliers\n15. Jump Rings\n16. Earring Hooks\nStep 1: Wooden Pieces\nThe wooden pieces should have a flat or pretty much flat side to them. They can be whatever size you want, but you want them to be a size that you can wear comfortably.\nAs I said earlier, you can use scrap pieces of wood if you have any. You will probably have more work because you will need to sand your scrap pieces to make them smooth and to shape them.\nIf you don't have scrap pieces, or you don't want to mess with that, you can buy premade little wood circles, squares, and other shapes at craft stores. I bought mine at our local chain craft store. You can even find them at Walmart. You just want pieces that are pretty thin and the diameter you want.\nSince I bought a variety pack, I have a couple sizes to pick from. I am going to use the largest circle size I have (you can see in the photo how big it is), but size is up to you.\nStep 2: How to Remove and Add a Drill Bit\nI put my #55 micro drill bit into the drill.\nOn my drill you hold the chuck (the piece were you put the drill bit) while you run the drill in reverse. This causes the end to open up so you can remove the drill bit that is in the drill.\n(The reverse/forward button is a little push in button that you should find somewhere above the speed trigger. You push on it one way and the drill runs in reverse. Push it in the other way and the drill will run forwards.)\nThen I place my #55 drill bit in the end and hold onto it with a few of my fingers so I can make sure it is straight. I turn the drill to run forwards. Slowly I run the drill until the end closes around the drill bit.\nNow we are ready!\nStep 3: Drill\nPlace your wood piece on a surface that you can safely drill on (not the kitchen table). Remember that your drill bit will be going all the way through the wood.\nYou may want to mark with a pen or pencil where you want the hole. You can carefully hold onto the wood piece with one hand while running the drill with the other. Just make sure your fingers are no where near the drill bit.\nHolding the drill straight up from the wood piece, place the bit where you want the hole. Slowly run the drill forwards until it goes all the way through the wood.\n*Alternatively, hold the piece in your fingers while you drill, but this is more dangerous! Be careful!\nTurn the drill to reverse, and run the drill as you bring the drill bit out of the hole. This helps make the hole smooth.\nMake sure to do this slowly because if you go too fast you may cause your piece to move or you might crack the wood.\nStep 4: Sand (optional)\nThe hole might have little rough edges, so we will sandpaper that.", "56" ] ]

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[ [ "Wrong results for $2$ stage multistep method $y_{n+2} - y_n = h\\left[(1/3)f_{n+2} + (4/3)f_{n+1} + (1/3)f_n\\right]$\nI need to fix a code to utilise the $2$ stage multistep method :\n$$y_{n+2} - y_n = h\\left[(1/3)f_{n+2} + (4/3)f_{n+1} + (1/3)f_n\\right]$$\nSince this is an implicit method, I used a Newton-Raphson approach for the final determination of $y_{n+2}$.\nBelow, is my attempt at a code implementing the already given rk4 method (runge-kutta 4) for the first approximation steps :\nfunction [tout, yout] = newcorrect(FunFcn,t0,tfinal,step,y0)\nmaxiter = 1000;\ntolnr = 1e-9;\ndiffdelta = 1e-6;\nstages=2;\n[tout,yout]=rk4(FunFcn,t0,t0+(stages-1)*step,step,y0);\ntout=tout(1:stages);\nyout=yout(1:stages);\nt = tout(stages);\ny = yout(stages).';\n% The main loop\nwhile abs(t- tfinal)> 1e-6\nif t + step > tfinal, step = tfinal - t; end\nt = t + step;\nyn0 = y;\nynf = yn0;\nyn = inf;\niter = 0;\nwhile (abs(yn - ynf)>= tolnr) && (iter < maxiter)\ndf = 1/diffdelta * (feval(FunFcn,t, yn0+diffdelta) - feval(FunFcn, t, yn0));\nyn = yn0 - 1/(1/3*step*df - 1) * (4/3*step*feval(FunFcn,tout(end),yout(end)) + 1/3*step*feval(FunFcn,tout(end-1),yout(end-1)) + 1/3*step*feval(FunFcn, t, yn0) -yn0 + yout(end-1));\nynf = yn0;\nyn0 = yn;\niter = iter + 1;\nend\ny = yn;\ntout = [tout; t];\nyout = [yout; y.'];\nend\nend\nThis is to be used for showing experimentally that when you divide the step by two, the fraction of the maximum absolute errors per consecutive different steps $h$ is approximately equal to $2^{-p}$ where $p$ is the order of the method. The method is proven to be of order $4$. The exercise whishes the initial starting point to be $k0=2$ thus I created the following script :\nclear all;\nt0 = 1;\ntfinal = 3;\ny1 = 2;\ntout =t0:0.01:tfinal;\nk0 = 2;\nkf = input('enter final k:')\nfor k = k0:kf\nh(k-1) = 2^(-k);\n[tout,yout] = newcorrect('f0', t0, tfinal, h(k-1), y1);\noutputs{k-1} = [tout,yout];\nend\nfor i = 1:(kf-1)\nmaxabserror(i) = max(abs(outputs{1,i}(:,2)-f0true(outputs{1,i}(:,1))));\nend\nfor i = 1:(kf-2)\nconsmax(i) = maxabserror(i+1)/maxabserror(i);\nend\nThe function f0 and f0true are :\nfunction yprime = f0(t,y)\nyprime = (t.^2 + y.^2)/(2.*t.*y);\nend\nfunction y = f0true(t);\ny = sqrt(t.", "935" ], [ "Global truncation error behavior at fixed time step\nI am trying to solve the following diffusion equation problem:\n$\\frac{\\partial f}{\\partial t}=\\frac{\\partial (D\\frac{\\partial f}{\\partial x})}{\\partial x}+S$\n$D=1+x^{2}+\\sin(x)$\n$f(x,0)=1 , f(0,t)=f(1,t)=1$\n$S $ is choosen adequately in order to have $f_{ana} = 1+\\sin(\\pi x)\\sin(\\pi t)$ as the analytical solution of the equation to be compared with the numerical one.\nThe equation was discretized using a finite difference/ Central method in space (2nd order in space) and Euler implicit in time (1st order in time).\nThe global error behavior should follow asymptotically $\\dfrac{A}{dx^{2}}+\\dfrac{B}{dt}$ with $A$ and $B$ that do not depend on $dt$ and $dx$.\nNow after implementing the resolution algorithm on Python, and constructing the error plot variation in terms of $dx$ (2nd norm and $\\infty $ norm ) for a fixed $dt$, I was expecting a behavior following $C+\\dfrac{A}{dx^{2}}$, with a \"smooth\" decrease in the convergence rate as C would become more predominant for smaller $dx$ till reaching the constant. What I got instead (and what I don't understand) is a small increase in the convergence rate, before recovering to the constant value (\"reversed bell\" behavior).\nIs it normal to have an \"acceleration\" of the convergence rate in this case ? Is it a problem related to rounding effect of the very small space error ?\nHere is the ready-to-use Python code :\nimport numpy as np\nimport matplotlib.pyplot as plt\nimport scipy as sci\nfrom scipy.sparse.linalg.dsolve import spsolve\nimport scipy.sparse as sp\nimport sympy as sym\n#Symbolic calculation\nx, t= sym.symbols('x t')\nDxx_1=1+x**2+sym.sin(x)\nfi_1=1+sym.sin(sym.pi*x)*sym.sin(sym.pi*t) #Analytical solution\nSoi_1=-sym.diff(Dxx_1*sym.diff(fi_1,x),x)+sym.diff(fi_1,t)#Source\nDxx_2=sym.lambdify((x),Dxx_1,\"numpy\")\n#Conversion from symbolic to function\nSoi=sym.lambdify((x,t),Soi_1,\"numpy\")\nfi=sym.lambdify((x,t),fi_1,\"numpy\")\n#Lists that will contain the trucation errors for plot\nErr00=[]\nErr2=[]\n#list of the number of points in the domain\nN=np.array([10,20,40,60,80,100,120,140,160,180,200,320,640])\n#Loop on Nx\nfor Nx in N:\n#Space domain definition\nlx=1.0\nox=0.0\ndx=(lx-ox)/(Nx)\nx1=np.linspace(ox+dx,lx-dx,Nx-1)#Points of the domain where f is unknown\nx2=np.linspace(ox,lx,Nx+1)#All points of the domain\n#Diffusion coefficient\nDxx=Dxx_2(x2)\n#Initialisation\nf=fi(x1,0)\n#Time grid\nt1=0.5\ndt=0.0001\nNt=int(t1/dt)\n#Implicit matrix definition - Sparse method\ndiag0= -(2*Dxx[1:-1]/(dx**2))\ndiag1= ((Dxx[2:-1]-Dxx[:-3])/(4*dx**2))+((Dxx[1:-2])/(dx**2))\ndiag_1= (-((Dxx[3:]-Dxx[1:-2])/(4*dx**2))+((Dxx[2:-1])/(dx**2)))\ndata = [-dt*np.append(diag_1,[0]),1-dt*diag0,-dt*np.", "935" ], [ "Neumann boundary condition FD implementation for instationnary diffusion equation\nI am trying to solve this diffusion equation : $\\dfrac{\\partial D\\dfrac{\\partial f}{\\partial x}}{\\partial x}+S = \\dfrac{\\partial f}{\\partial t}$ ($D$ is not constant and varies according to $x$) with the following BC: $f(x,0)=1 , f(0,t)=0, \\dfrac{\\partial f}{\\partial x}(1,t)=0$\nI am using a central finite difference scheme (2nd order) for space and Euler explicit for time (1st order). The discretized $[0..1]$ domain contains the $x_{i}$ points, $i \\in [0..N]$ ($x_{0}=0 , x_{N}=1$).\nThe implementation of Dirichlet condition at $x=0$ is simple. For the <PERSON> boundary condition, I saw a lot of references that treated simple cases, adequate for constant diffusion coefficients and stationnary cases, like the ghost point, that I can't consider in my case(Diffusion coefficient can't be evaluated out of the domain, ghost point envolves evaluation the equation on a point that is not inside the interior domain...", "935" ], [ ").\nSo I am trying something at my own and I want confirmation or correction if I omitted an important aspect in my work:\nThe discretized equation evaluated at $x_{N-1}$ involves the value of $f_{N}$. If we had Diricihlet condition at $x_{N}$, the problem would have been solved directly. But in our case, $f_{N}$ is unknown.\nWhat I did is that I treated the Neumann BC with a backward scheme (at the 2nd order to preserve the general order of the whole scheme) in order to have an expression of $f^{k}_{N}$:\n$\\dfrac{\\partial f}{\\partial x}(x_{N},k\\Delta t)=\\dfrac{-3f^{k}{N}+4f^{k}{N-1}-f^{k}_{N-2}}{2\\Delta x}=0$\n$f^{k}{N}=4/3 f^{k}{N-1}-1/3 f^{k}_{N-2}$\nthen I injected the new expression of $f^{k}{N}$ in the discretized equation at $x{N-1}$. Meaning that I did not add an equation to the problem as I would do for a stationnary problem but I injected the expression of $f^{k}_{N}$ inside the last equation.\nSo the unknown vector $f^{k}$ in a case of matrix writing would only contain $f^{k}_{i}, i\\in [1..N-1]$ (like in a full Dirichlet situation)\nIs it correct ?\nFor information, the matrix form of the discretized problem is : $f^{k+1}=Af^{k}+S+B$, with $B$ the vector containing the B.C , and $S$ the 2nd member vector", "935" ], [ "Floating point and global error in Euler Method\nInspired by this answer, I tried to understand when floating point errors come into visibility and to check it also comparing the plot of the numerical solution with Explicit Euler with the analytical one for this simple problem.\n\\begin{cases} y'(x)= L \\sin(x) \\ y(0)= 0 \\end{cases}\nwhere $L$ is a number. The Solution of the problem is $y(x)=L(1-cos(x))$. Notice that $$|L(\\sin(x)-\\sin(y)| \\leq L |\\cos(c)||x-y| \\leq L|x-y|$$\nso that the Lipschitz constant of the r.h.s is $L$.\nSolving this ODE with Explicit Euler, we have a global error that is of the order $O(e^{Lx}(h+\\mu))$ where $\\mu$ is the unit roundoff.\nTrying to use to <PERSON>'s argument, I'd say that floating point errors come into visibility as $e^{Lx} \\mu \\approx 1$, i.e.", "521" ], [ "$x \\approx \\log(\\mu)/L$. I'd expect that for such an $x$, the numerical solution will deviate from the correct one.\nTo see this, I tested for $L=10$. It turns out that from about $x \\approx 3.67$ I should start seeing some small problems, but in my plot it seems that everything is fine also for \"extremely\" large times, as may be seen in this plot with $T=40$ as final time.\nMy question: Why can't I see a significative difference starting from that point? What's really happening?\nThe simple Python code is the following:\nimport numpy as np\nimport matplotlib.pyplot as plt\nL = 10\ndef Fun(t,x):\nreturn L*np.sin(t)\ndef Sol(t):\nreturn L*(1-np.cos(t))\ntf=40.0\nt0=0\nk = 0.01\nts = np.int(tf/k)\nt=np.linspace(t0,tf,ts+1)\ny=np.zeros((ts+1)) #trapz\ny0=0\ny[0]=y0\nfor i in range (0,ts):\ny[i+1] = y[i] + k*Fun(t[i],y[i])\nplt.plot(t,y,'o',label='Explicit Euler')\nplt.plot(t,Sol(t),'-',label='Solution')\nplt.title(\"Integration up to T=\"+str(tf))\nplt.show()\nplt.legend()", "509" ], [ "Impose Neumann Boundary Condition in advection-diffusion equation 1D\nwhen solving the advection equation in 1D that is:\n$$ \\frac{\\partial u}{\\partial t} + c\\frac{\\partial u}{\\partial x} = 0 $$ with $ u'(t,0) = 0$ and $u(t,L) = 0$ , $u(0,x) = u_{0} $\none numerical scheme is the FTCS (Forward time-centered space), but this numerical scheme is unstable.\n$$\\frac{u_{j}^{n+1}-u_{j}^{n}}{ h_{t}} = c \\frac{u_{j+1}^{n}-u_{j-1}^{n}}{ 2h_{x}} $$\nBut when solving\n$$ \\frac{\\partial u}{\\partial t} + c\\frac{\\partial u}{\\partial x} = \\alpha \\frac{\\partial^2 u}{\\partial x^2} $$ the advection-diffusion equation in 1D with $ u'(t,0) = 0$ and $u(t,L) = 0$ , $u(0,x) = u_{0} $\nSince the advection-diffusion equation is a second order equation I'd like to use a second order approximation.\nif we define $u_{k}^{n} := u(t_{n},x_{k}) $; $\\ \\ x_{k} = kh $ and $ \\ \\ k = 0,1,2,...,N$. $h$ is known as the mesh size or step size.\nFor the second derivative:\n$$ \\frac{\\partial^2u_{k}^{n}}{\\partial x^2} \\approx \\frac{u_{k+1}^{n}-2u_{k}^{n}+u_{k-1}^{n}}{h^2} = \\frac{u_{k-1}^{n}-2u_{k}^{n}+u_{k+1}^{n}}{h^2} $$ for $k=0,1,...,N-1$\nSince $u'(t,0) = 0$ and $ u(t_{n},L) = u(t_{n},x_{N}) = u_{N}^{n} = 0 $ we get the following matrix representation of the second derivative operator\n\\begin{equation} \\frac{\\partial^2}{\\partial x^2} \\approx L_{2} = \\frac{1}{h^2}\\left(\\begin{matrix} -2 & 1 & & 0\\ 1 & \\ddots & \\ddots & \\ & \\ddots & \\ddots & 1 \\ 0 & & 1 & -2 \\end{matrix} \\right) \\end{equation}\nfor $k=0$ , we get\n$$ \\frac{\\partial u_{0}^{n}}{\\partial x} = \\frac{u_{0+1}^{n}-u_{0-1}^{n}}{ 2h} = 0 $$ this implies that $ u_{1}^{n}=u_{-1}^{n} $ and\n$$ \\frac{\\partial^2u_{0}^{n}}{\\partial x^2} \\approx \\frac{u_{0+1}^{n}-2u_{0}^{n}+u_{0-1}^{n}}{h^2} = \\frac{u_{0-1}^{n}-2u_{0}^{n}+u_{0+1}^{n}}{h^2} = \\frac{-2u_{0}^{n}+2u_{1}^{n}}{h^2} $$\nthus we have to modify the entry $1,2$ of $L_{2}$\n\\begin{equation} L_{2} = \\frac{1}{h^2}\\left(\\begin{matrix} -2 & 2 & & 0\\ 1 & \\ddots & \\ddots & \\ & \\ddots & \\ddots & 1 \\ 0 & & 1 & -2 \\end{matrix} \\right) \\end{equation}\nWhat I have done, is $\\mathbf{impose \\ the \\ Neumann \\ boundary \\ condition}$ in $L_{2}$ .", "935" ], [ "Error $L_{2}$ convergence in Finite Element for Poisson Equation\nI have written a Matlab code to solve the equation $-u'' = f$ with conditions $u(0) = u'(1) = 0$ on the domain $x \\in [0,1]$. I tested the code with $f(x) = -2, \\forall x\\in [0,1]$. I check the plot with one of element $n=8$, and the result $u = u^{h}$ agrees:\nHowever, I am testing the convergence error $L_{2}$ for the problem $n=8,16,32,64$.", "935" ], [ "The error plot I get is not giving me the result of $O(\\Delta x^{2})$ where $\\Delta x$ is the fixed step size. I am trying to find if there is a bug. Why is a big change in my error between $n=16$ and $n=32$? It is probably something small in my code, but for some reason I can't figure it out. Thanks in advance!!!! Furthermore, I use a uniform grid $[0,1]$ so $\\Delta x (h)$ is a fixed step size.\nThis is the code that I solve with Matlab and a driver to test the convergence:\n``` % script to generate the uniform mesh for Finite element: % dom = [a b] where a < b is the domain of our problem function [xgrid, h] = generate1d_uniform(n) h=1/(n-1); xgrid=linspace(0,1,n); end\n% implement the solver for Finite Element for Poisson equation function uh = fem1d(n,f)\n% generate the uniform mesh: [x,h] = generate1d_uniform(n); % load vector b = loadVector1D(x,h,f); A = StiffMat1D(x,h);\n% since u0 is 0 Ae=A(2:end,2:end); fe=b(2:end); uhe=Ae\\fe;\n% adjust the boundary condition u(0)=0 uh=[0;uhe]; end\n% function to assembly load vector b: % f is the source function; x is from the domain generate by 1d mesh function b = loadVector1D(x,h,f) n = length(x)-1; b = zeros(n+1,1);\nfor i = 1:n b(i) = b(i) + f(x(i))(h/2); b(i+1) = b(i+1) + f(x(i+1))(h/2); end\nend\n% function to load the stiffness matrix for A: % the local stiffness matrix is of the form Ak = 1/h [1 -1; -1 1] % adjust the A(1,1) = 1 and A(n+1,n+1) = 1 for boundary conditions in this % case u'(1) = 0 and u(0) = 0 function A = StiffMat1D(x,h) n = length(x)-1; Ak = spdiags(ones(n+1,1)[-1 2 -1],-1:1,n+1,n+1); % Adjust the boundary condition u'(1) = 0 Ak(1,1) = 1; Ak(end,end) = 1;\nA = (1/h)Ak; end\n%%% DRIVER for convergence error %%% function driver1 clear all; clc; format short; %number of elements set: nset=[8,16,32,64];\n% source function in part (a) f = @(x) -2.*(0<=x & x<=1);\n% exact solution: u = @(x) x.^2 - 2*x; %define the error L2 set to store the values: errorL2=zeros(size(nset)); hset=zeros(size(nset)); % iteration: niter=length(nset);\nfor i=1:niter\nn=nset(i);\ndisp(n)\nerrorL2(i)=compute_error(u,n,f);\nend\n% write the table for error L2: T1=table(nset', errorL2'); T1.Properties.VariableNames ={'n elements', 'Error L2'}; writetable(T1,'TableError.", "935" ], [ "Why is the central difference method dispersing my solution?\nI am solving numerically the ODE $\\ddot x(t)=-c\\dot x(t) -\\sin(x(t))+F\\cdot \\cos(\\omega t), \\;\\dot x(0)=x(0)=0$ for $t\\in [0,20\\pi]$ on an $N=2000$ dimensional grid. I am working on Python, and I replaced the time derivatives by the finite difference operators \\begin{align} \\dot x(t)&=\\frac{x(t+dt)-x(t)}{dt}, & \\ddot x(t) &=\\frac{x(t+dt)-2x(t)+x(t-dt)}{dt^2} \\end{align} Thus, the discretized ODE can be solved by the extrapolation scheme $$x(t+dt) =\\frac 1{1+c\\cdot dt}\\Bigr( x(t)\\bigr(2+c\\cdot dt\\bigr) +x(t-dt) + dt^2\\bigr( -\\sin(x(t))+ F\\cdot \\cos(\\omega t)\\bigr) \\Bigr) $$ I performed this scheme and the result was great. To compare, I also reduced the 2nd order ODE to a system of two 1st order ODE's \\begin{align} \\begin{cases} \\dot x=y\\ \\dot y(t) =-cy(t)-\\sin x(t)+Fcos(\\omega t) \\end{cases} \\end{align} with initial values $(x(0),y(0))=(0,0)$.", "935" ], [ "Solving this system with a Forward-Euler scheme, yields the a solution that starts similar to the first scheme, but is not quite the same. Note that using the Forward-Euler scheme is the same as solving for $x(t+dt)$ after replacing the derivatives by the forward difference operator $f'(t)=\\frac1 {dt}(f(t+dt)-f(t)).$ However, if we rather replace the derivatives with the central difference operator $$f(t)=\\frac{f(t+dt)-f(t-dt)}{2\\cdot dt}, $$ we obtain the following extrapolation scheme: \\begin{align} \\begin{cases} x(t+dt) = x(t-dt)+2\\cdot dt \\cdot y(t)\\ y(t+dt) = y(t-dt) + 2\\cdot dt \\bigr( - c y(t) -\\sin x(t)+ F\\cdot \\cos(\\omega t) \\bigr) \\end{cases} \\end{align} Performing this scheme with values $c=0.05, \\; \\omega = 0.7, \\; F = 0.4$ yields a horrible solution. I do not know what is going on, here are the plots for the solutions obtained in each scheme.\nAlso, here is the code I wrote\n```import numpy as np import matplotlib import matplotlib.pyplot as plt\ntmax = 20 * np.pi tmin = 0 n = 1000 dt = (tmax-tmin)/(n-1) t = np.linspace(0,(n+1)dt,n) c = 0.05 w = 0.7 F = 0.4 x = np.zeros(n) y = np.zeros(n) for i in range(1,n-1): \"\"\" First method \"\"\" x[i+1] = (x[i] * (2+ cdt) - x[i-1] + (dt 2) * (-np.sin(x[i]) \\ + F * np.cos(wt[i])) )/(1+cdt) plt.scatter(t,x,s = 0.5) plt.title('Second order ODE scheme') plt.xlabel('t') plt.ylabel('x') plt.show() plt.close()\nfor i in range(1,n-1): \"\"\" Second method \"\"\"\nx[i+1] = x[i] + dt * y[i] y[i+1] = y[i] + dt * ( - c * y[i] - np.sin(x[i])\\ + F * np.cos(w * t[i])) plt.scatter(t,x,s = 0.5) plt.", "509" ], [ "Discretization Error amplification instead of stagnation to machine precision\nI wrote a code on Python 2.7.5 to solve numerically the following differential equation.\n* $\\frac{\\partial^2f}{\\partial x^2}=-S$\n* $S=\\pi^{2}\\sin(\\pi x)$\nS is chosen that way in order to have $f= \\sin(\\pi x)$ as the exact solution, that can be compared with the constructed solution.\nThe differential operator is discretized using a second-order central finite difference method.\nWhen running the code, the order of magnitude of the evolution of the discretization error Err is correct (2nd order) for the first batch of points of N (10,20,40,80,100,800,2000,5000) (goes down to 10e-11).\nBut I found that for very small dx meaning, very big Nx (10000,50000,100000,600000,900000), Err doesn't stagnate at the machine precision error (as expected) but goes up for several magnitude orders, and even worse, the discretization error Err deteriorates (up to 10e-7).\nIs it a problem in the precision/round managment of Python for very small numbers, or is it normal to have even worse Error for that amount of points ?\nI tried to write the problem in different ways (Matrix, Loops, Matrix inversion technices) but the same phenomenon happened.\nimport numpy as np\nimport matplotlib.pyplot as plt\nimport scipy.sparse as sp\nfrom scipy.sparse.linalg.dsolve import spsolve\nErr=[]\nN=np.array([10,20,40,80,100,800,2000,5000,10000,50000,100000,600000,900000])\n#Loop on the number of points used for the discretization of the 1D domain\nfor Nx in N:\ndx=(1.0)/Nx# fixed distance between two consecutive points in the domain\nx = np.linspace(dx,1.0-dx,Nx-1)# points of the 1D domain\n#contruction of the diff operator discretization Matrix\ndata = [np.ones(Nx-1), -2*np.ones(Nx-1), np.ones(Nx-1)]# Diagonal terms\noffsets = np.array([-1, 0, 1])# Their positions\nLAP = sp.dia_matrix((data, offsets), shape=(Nx-1, Nx-1))#Sparse matrix\nS = np.pi**2*np.sin(np.pi*x)*dx**2# Second member\nf = spsolve(LAP,-S)#Resolution of the matrix system\nf_ana=np.sin(np.pi*x)#The exact solution\nErr.append((np.absolute((f_ana-f))).max())\nplt.figure()\nplt.plot(N,Err,N,N**float(-2),'--')\nplt.legend(['Err','Theoretical asymptotic behaviour'])\nplt.xlabel('dx')\nplt.ylabel('Err')\nplt.xscale('log')\nplt.yscale('log')\nplt.show()", "509" ] ]

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[ [ "There are several interesting components in soil:\n* The carbon content, mostly in the form of humic acids - a proxy for how well the soil an store nutrients and water and for wether there's a living soil microbiome (earthwormes etc.). Soil carbon is also removed by biological processes outside of special circumstances like peat foramtion. Carbon is added by decaying plant matter and other organic matter, like faeces of animal (wether natural or manure applied as fertilizer)\n* The macronutrient content, what we think of as fertilizer - usually N, P, K, (and to a lesser extent) S are considered macronutrients that plants need. There is also the question on how available those nutrients are. Macronutrients are added as fertilizer. Macronutrients that come as part of organic matter (e.g. N in proteines) must first be digested by something. This is why earthworms and the like are important. Macronutrients can be washed out and aer used by plants.\n* Micronutrients - trace elements, salts etc.", "1022" ], [ "that plants need. Again, it is important to understand that not so much the total amount in a given volume of earth is interesting but the amount actually available to a plant (Mg tied up in the middle of some rock won't help). I think these cycle like macronutrients, but the slow breakdown of sand and rock is also an important source. But this is a slow process. On intensivly used fields, these will be added in addition to fertilizer. This gives you a hint that the processes supplying micronutrients happen slowly.\nSo if you think of soil as the sum of these three categories you can look at how fast or slow each is replenished and used. FArmers will watch for the nutrient balances as well as for the carbon balance of their fields.\nHowever all of these influence each other, soil is really complex. While you can argue that soil is renewable since in some cases all three broad categories of stuff will be replenished eventually, IMO this misses the point how slowly this happens. It also misses the more important point that soil is not simply a mixture of stuff but ideally a living system where things happen.", "1022" ], [ "Short answer is it can't form when the temperature of the water is above the freezing point. As <PERSON> and @tpg2114 have pointed out the temperature of water on surfaces will frequently be lower than the air temperature.\nI'm answering just to clarify that the wet-bulb temperature is only indirectly relevant. The wet bulb temperature is not (definitionally) the lowest temperature an object can reach as a result of evaporation. It does provide a lower bound on the temperature that can be reached under outside conditions as experimentally at these pressures it turns out that the rate of convective heating of the water by the air tends to be faster than the rate of evaporative cooling of the water.", "108" ], [ "Thus, the coldest evaporative cooling can reduce the water will be no lower than the coldest the water can make the air. This, of course, occurs when the air evaporates as much water as possible and the total amount of air is very large compared with the water left (so the water contains a negligible amount of thermal energy and is cooled to the air temperature) and at a temperature equal to the wet bulb temperature.\nWorking outside one also has to deal with radiative and convective transfers from a very very large volume of air and if still air is left around the water reservoir the rate of cooling by evaporation will drop as the air approaches saturation and the huge body of dry air will start to heat the reservoir faster than it is being cooled. Experimentally, it turns out that high wind speeds and shielded reservoirs give the largest cooling but can't actually reach the wet bulb temperature.\nHowever, as suggested here at lower air pressures convection does not ultimate dominate evaporative cooling. In this case one can reduce the water to a lower temperature than the surrounding air and the wet bulb temperature is no longer a minimum value for the temperature evaporation can reduce surface to. Essentially this works since you are letting the highest energy molecules in the water escape and thereby reducing the average kinetic energy of the remaining molecules and the air is so thin that this effect cools the water faster than the neighboring air can heat it back up.", "108" ], [ "Most of the interesting \"weather\" and dynamics in the lower atmosphere arise from convection.\nI think the link that was posted was mainly about how convection dominates in the lower atmosphere and and radiation effects dominate in the upper atmosphere, and wanted to see what the effect of would be if one artificially looked at the problem without convection. As pointed out in comments and other answers, it is unrealistic to not have convection. The link article by having a thin ocean was mainly trying to set a boundary condition for the model, and if I read it correctly that if the ocean was thick the equilibrium temperature would end up same if you waited long enough. One way to interpret the article is that the convection in the lower atmosphere mixes up the fluid (air) in such a way that the surface doesn't get as hot as it would without having a layer of atmosphere mixing.\nFrom a world building perspective, I think to get at the heart of your question it is about how could you control the temperature of the planet assuming that radiative processes are dominating the heat transfer balance.\nThe answer I think would be by how much reflectivity (from the surface or perhaps clouds) and emissivity the planet has. From a climate science point of view, this is a big deal. In the air how much to contrails from air traffic change the heat ballance, surprisingly to me, apparently it is measurable.", "108" ], [ "On the ground, or ocean, how much soot from combustion is landing on the snow, or how much ice coverage in the arctic ocean matters in a lot of these models how the light from the sub is trapped or reflected is important.\nSo for your purposes, you have the light from the sun hitting the planet and the light and heat from the planet radiating into space. Neglecting some details, that the planet may have started out as hot mess of molten rock, and over time new materials from space may be adding water etc. That should come into equilibrium.\nA short light article with a graphic is at\nhttps://www.physics-in-a-nutshell.com/article/17/surface-temperature-of-the-earth\nThe atmosphere acting as a filter as to how to how much of the light and heat from the sun is reflected, how much is transmitted to the surface, and how much of the higher energy photons are absorbed by the gasses in the atmosphere or by the ground and turned into heat (lower energy photons) that would go through the filter and radiate into space.\nTo dial in the temperature for your world, the easiest thing would be to fiddle how much light is reflected and absorbed. The knobs you can turn (ignoring the convection) would be to add more gasses from volcanoes like CO2 that might absorb and trap heat strongly, but not add a lot of particulates from the volcanos, or clouds in the atmosphere that might reflect more of the light before it gets absorbed. Without CO2, from the volcanos, maybe the oceans are frozen before the eruptions and the earth is very shiny and reflective. Or you could add plants, and they could consume the CO2, and perhaps the plants change the reflectivity of the oceans, or maybe the oxygen from the plants starts to oxidize the land etc.\nVolcanoes are not the only thing but just an example of something that can change the heat balance in a short period of time. But basically changing the Albedo of the planet (with or without) a convective atmosphere can change the heat balance and the surface temperature significantly.", "184" ], [ "You can follow the key aspects of group theory and symmetry for chemistry without ever taking formal abstract algebra courses.\nThe key aspects are presented in survey and specialized chemistry texts. Probably all the exercises on different molecules (and IR modes and the like) will actually give you MORE of a feeling for the complexity of physical symmetry than a math first attitude would.\nThis is not to say it hurts, but you totally don't need math based group theory.\nConsider, for instance, <PERSON> has a remark (in horror) in his advanced math book for physics at the 200+ space groups for crystals. But a crystallographer or solid state chemist finds them interesting. [Note that this is not even an aspect of chemistry being very detailed...millions of compounds. It's straight up from the math itself...could be lattices of twigs for all we care. But the mathematician just hates this kind of complexity. A chemist is used to it since he has to organize families of organic compounds and the like.]\nPersonally I think if you want to dive deeper, would start with specialized books on group theory for chemistry (will have a little more than the touch in your survey inorganic text). Here there are sort of two schools:\nA. Molecular, with emphasis on point groups and vibrational modes (IR).", "800" ], [ "Think basic coordination compounds of metals.\nB. Solid state, with emphasis on space groups and crystallography. Think metal oxides or similar.\nOf course you can and will have crystalized groups of molecules as well, so both are relevant.\nOnly after digging deep into some of the chemical based stuff would I maybe consider the need to go back and get into an abstract algebra based development of group theory (probably starting at set theory and involving things like rings and fields that don't even apply to your need).\nAnd by the way, if you get seriously into crystallography, you can spend a lot of time on that. And a group theory mathematician won't have a feeling for how to spot flaws in crystal structures (either those that don't make sense chemically OR those that are little logical flaws of the math, e.g. equivalent structures).\nIf anything learning more vector calc and tensors (and from an applied, simple perspective...not total math theory killer) would help you more. Even that is basically just needed if you become a crystallographer. An experimental inorganic chemist working on molecules really doesn't need it--all his xtal structure determinations are outsourced. Solid state guys tend to do more of this themselves but even here, a lot of it is playing with programs on the computer and the theory of the x-ray geometry is really not needed. More a careful attitude to look for reasonable chemistry and where solved structures have more uncertainty (\"thermal parameters\").", "561" ], [ "We breath oxygen primarily because it's highly electronegative and hence works as an electron attractor in the electron transport chain system of atp production. This is a rather specific metabolic system and it's far from foundational, tons and tons of bacteria don't have this type of energy system, (in fact even humans have several others in addition to this one!)\nIn fact, there are really existing earth bacteria that use metals in their metabolic systems, and frequently absorb environmental sulfur or oxygen (or probably other things, maybe not hydrogen though, H2 is very stable) as a way of breaking down metals into more usable forms.\nReally you've just got to decide how detailed you want to get with this. Fully describing the chemistry of a totally novel metabolic cycle seems like it would be pretty hard, certainly it's above my pay grade. At the same time, I wouldn't doubt for a second the plausibility of \"a Bacteria which metabolizes [some metal] by absorbing [some gas] in a low oxygen atmosphere\". Hell, there's probably one on Earth that fits the bill.\nTo fill out this response with some more specific information, you can look at a couple of the following things:\n1: Sulfate Reducing Microorganisms: https://en.wikipedia.org/wiki/Sulfate-reducing_microorganisms -- these are examples of bacteria that \"breath\" sulfates instead of oxygen to power their respiration. In other words, they use sulfates as the final electron acceptor in their electron transport chain.", "938" ], [ "These are prokaryotes however. Some of these are called Chemolithoheterotrophs, which is the class of bacteria here that reduces inorganic material rather than organic material, which is kind of the thing you are looking for. 2. https://microbewiki.kenyon.edu/index.php/Dissimilatory_metal_reduction Here is a short article talking about how microbes can \"consume\" metals to produce energy. In your post you said you wanted the microbe to consume metals to gain mass, but keep in mind that for the most part the mass of a single microbe is naturally limited by scaling factor difference between volume (~mass) and surface area (~max \"eating\" rate), so for a colony of bacteria to gain mass by consuming metals you just need a metal to be \"consumed\" (usually this means corroded or oxidized) as part of the colony's metabolic process.\nI'd hoped to find an example of a specific Earth bacteria fitting your criterion, but I wasn't able. However, nothing about what you're asking for is too 'out of this world' (yuk-yuk) certainly the individual elements you're asking for are well represented and pretty well understood.", "561" ], [ "The answer really depends on how you think of invasive. One extreme answer is to say that all things are relative, and that the concepts of local and invasive are all relative. This matters to a certain extent because we (ecologists) draw a fuzzy line between invasive and naturalized (http://onlinelibrary.wiley.com/doi/10.1046/j.1472-4642.2000.00083.x/abstract). You could start with some basic species that we all think of as either good, local, or neutral. Take the earthworm. Most people think of it as a common native species, but it's actually an invasive species that has radically changed much of North America that came over with the Europeans (http://www.dnr.state.mn.us/invasives/terrestrialanimals/earthworms/index.html). Similarly, brown trout are also invasive, coming to the US in the 1800's (http://www.dfg.ca.gov/fish/resources/WildTrout/WT_BrownDesc.asp).\nAs far as why invasive species succeed, it's still an open question. What you reference is the enemy release hypothesis, but there are others such as disturbance, diversity of the new community, and just the traits. Here's a good review: http://onlinelibrary.wiley.com/doi/10.1002/ece3.431/abstract http://onlinelibrary.wiley.com/doi/10.1111/j.1461-0248.2009.01418.x/full\nTo answer your question about adapting, I wouldn't trust your memory.", "759" ], [ "It's important to keep in mind that most likely your memory is flawed, and you are only observing a very limited number samples with an incomplete sampling methodology. For instance gypsy moths undergo wild population fluctuations, and have for over 100 years. (http://link.springer.com/article/10.1007/PL00012004). How well do ecosystems bounce back from invasions depends on lots of factors. Often time the ecosystem can survive, but the some species won't. An easy example would be Norther Hardwood forests. Chestnuts (extirpated by an invasive fungus)are mostly gone from the wild, but the forest persists, as well as many of the species that rely on them. So in part the answer to your question depends on scale. The forest survived, but an individual species was nearly destroyed.\nEcological economists have tried to put a value on the destruction that invasive species have caused too (http://www.sciencedirect.com/science/article/pii/S0921800904003027).", "3" ], [ "In terms of energy conservation a human being is more similar to a car with lots of internal frictions than an ideal rolling body. As the wheels and gears grind along eachother energy is inevitably converted into heat and the combustion engine itself will keep running even if it is disconnected from wheels burning fuel even when standing still. The frictions of your joints and inside your muscles are just as real although not really the most signifi\nWhen it comes to walking there still is some gravitational work involved as the knee moved up and down and whatever kinetic energy in the leg is gained as it \"falls back to the ground\" will be turned into heat upon impact with the ground. That said walking on a flat plane involves less of this kind of work than going up some stairs or running where you bob up and down more and all things considered walking is still not very tireing.\nHowevert he sensation of becoming tired due to physical stress (muscular fatigue) has more to do with the chemistry of how our muscles produce work than the total amount. After all if running out of energy was what made you tired chugging sugar water while running should help you a lot more than it demonstrably does.", "174" ], [ "Rather the issue is waste products of the chemical reactions (the \"exhausts\") build up faster than the body can move them out of the tissues, causing damage or inhibiting the reactions. Along with simple friction damage at the joints the body eventually reacts by producing tiredness or a pain response to stop you from continuing. The more work produced the faster this happens but it takes longer if your body is more capable of moving compounds in and out of the tissues or if you have become desensitized to the pain response.\nMuscles are also mechanically peculiar in that they can require a lot of energy to maintain static poses. Holding up your arms out to your side and completely still requires no mechanical work and a locked metal beam could do this forever but we quickly get tired. As you walk your muscles also transitions through states which might be statically draining but this is less of an issue than in some other situations.\nGenerally the human body is not very instructive when trying to understand physics even though it obeys the same principles.", "174" ], [ "1) The authors propose that this is a distinct species based on a number of physiological and genetic tests. To quote the summary of your linked paper\nIn summary, the phylogenetic and genetic distinctiveness and differential phenotypic properties were sufficient to categorize these three ISS strains as members of a species distinct from other recognized Methylobacterium species. Therefore, on the basis of the data presented, strains IF7SW-B2T, IIF1SW-B5, and IIF4SW-B5 represent a novel species of the genus Methylobacterium, for which the name Methylobacterium ajmalii sp. nov. is proposed.\nThis indicates (emphasis mine) that they think that these isolates are distinct enough from species that we have found on Earth to make the isolates a species. This is a species that we haven't found on Earth, but unsurprisingly it is closely related to species from the same genus that have been found on Earth and on the ISS\n2) The authors make no statements about how the species came to be there that I could see, only that it is a novel species from the ISS, which has not been found on Earth.", "3" ], [ "No mechanisms for arisal are postulated, and the authors wisely did not speculate on this at all (speculation on results is frowned upon in science). One of the reasons they did not speculate on this will be that testing mechanisms whereby speciation has occurred is very difficult, especially as they would need to mimic in the lab the conditions in the ISS and show which conditions were important for the speciation. These experiments would be technically challenging and very time consuming.\nIt is worth noting that we don't really know the rate of species differentiation on Earth, let alone in space, partly because Earth is so covered in bacteria that proving that one evolved in the environment is difficult as it is hard to prove that you didn't just miss it last time you looked. To quote the paper I linked above:\nFor example, a single gram of soil can harbour up to 1010 bacterial cells and an estimated species diversity of between 4·103 to 5·104 species .\nHowever, the ISS is one environment where it might be easier to see these sorts of events because it is relatively micro-organism free, and we have prior samples to go back and compare to. For some comparison of the numbers, I turn to the second paper you linked, which found:\nOf the total bacterial and fungal isolates that grew, 133 bacterial isolates and 81 fungal isolates were identified by <PERSON> sequencing... ...When the ASVs were summarized to the genus level, 121 taxa were detected, 77 of which could be assigned to known genera\nand\nOverall, the number of bacteria (combination of R2A and BA growth) isolated from the ISS from all 24 samples ranged from 6.7 × 103 to 7.8 × 1010 CFU/m2\nSo quite high numbers of cultivatable bacteria (CFU = colony forming units, a measure of how many bacteria will grow per sampling), indeed as high as those found in a gram of soil, but very low species diversity compared to the soil.\nIt is still difficult to prove that this is a new species evolved strictly on the ISS, but it does seem logically likely that evolution will happen on the ISS, as it does anywhere that life is present (as far as we know).", "3" ] ]

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[ [ "Probably for the same reason horses were chosen in the real world: Of the animals that can be domesticated, horses arguably make the best mounts. There are something like 150 real-world species of large land animals, and of these, only about a dozen can be domesticated. The rest might be captured and trained, or possibly raised from infancy and bonded with, but they can't be produced in quantity or bred for specific purposes.\nAgain in the real world, there are basically six traits that a species has to have to make it possible to domesticate. This is mostly summarized from Germs, Guns, and Steel: 1) Diet - you have to be able to feed it. Large carnivores generally fail this test pretty hard. 100 tons of grain will feed 10 tons of herbivores or omnivores, but those will in turn only feed 1 ton of carnivore. Horses can eat grass. 2) Growth Rate - If an animal takes 15 years to reach maturity instead of one, it's going to be cost-prohibitive in most cases. That's why we don't have Ape-ranchers. 3) Captive breeding - can't do selective breeding if you can't select who it breeds with. Some species just won't breed in captivity. Some need elaborate mating rituals or they won't conceive (ex: cheetahs). Some have complicated territorial requirements (ex: vicunas).", "376" ], [ "4) Personality - The animal has to have a disposition you can live with. Hippos will try to kill you just to see if they can. Grizzlies are prone to violent rages when frustrated, and psycho-girlfriend levels of jealousy. Zebras are irascible SOB's, especially as they get older - they'll bite you and drag you around a bit if they don't like something they imagine you did. 5) Calmness - they can't be too prone to panic. Gazelles have never been successfully domesticated because they will bolt blindly at the first sign of strangeness and either leap over their enclosure wall or bash themselves senseless against it. 6) Social Structure - There has to be some kind of social structure that a handler can take advantage of. All large domesticated animals have five features in common: a) they live in groups, b) they maintain well developed dominance hierarchies within their groups, c) those hierarchies remain fixed once established, d) they can imprint on the creatures around them while young and accept a human handler as part of the group, and e) they have overlapping home ranges rather than exclusive territories. 7) Suitable as Mount - On top of all that, if you want them domesticated specifically as mounts then they have to be capable of resting while standing, traveling long distances, carrying sufficient loads, moving fast, etc.\nTo make room for horses, you just have to select one of the domestication criteria that each of the fantasy mounts fail - or at least compares unfavorably to horses. Giant chickens might fail for the same reason as ostriches (bad basic skeletal structure for long distance load bearing), giant wolves might bond too closely with their handlers to ever raise for sale, etc.\nThe fantasy mounts will still be used if they exist - giant chicken races could be a thing people bet on, giant ants might be used for mining, and every military will want flying scouts regardless of the price. They will all be breathtakingly expensive of course; your typical farmer won't have one. But even nobles who can afford whatever they want will likely pick a horse over a giant beetle. Kind of like why you would choose to drive a car instead of a backhoe on your daily commute.", "376" ], [ "The logistical answers are very good, but in terms of what actually happens on the battlefield:\nHorses are faster than lion people\nOn a large enough plain, the existence of well-trained horse archers on one side of the battle but no horses on the other is almost enough to guarantee victory. If they can't be reached, they are free to take potshots at their enemies with relative impunity. They outrange their enemies, because you can shoot farther if you're charging at your target. If there's no easy way for the lions to entrap the horse archers, they can kite them around the battlefield until they get tired and go home. It should be noted, though, that horses will tire faster than lionfolk - bipedal movement is much more efficient.\nAvoid breaking lines at all costs\nThe lion's ideal situation is a chaotic brawl without a clear direction of attack or defense. At that point, it's a few thousand one-on-one fights with a clear advantage on the lion's part.\nNormally, the go-to would be shield walls here. But if lions can throw a man, they can also rip him out of a formation, so a traditional shield wall won't do here. Additionally, male lions can probably vault over the frontlines, which would be very bad.\nInstead, go with polearms. Very long polearms that mean that by the time the lions can touch the frontline, they have to deal with minimum three layers of soldiers stabbing at them, plus whatever archers are available.", "358" ], [ "The soldiers must be trained to advance forward when the guy in front of them dies, or the line will break.\nAdapt equipment\nCertain things which make sense when fighting humans don't make sense here. Shields are the big one - a standard shield could be grabbed by a lion, breaking your wrist or throwing you around. An alternative might be a buckler or a hefty gauntlet - a small shield that doesn't provide much surface to grab but still gives you a surface to bock an edged weapon with (block meaning redirect in this case). Alternatively, ditch the shield and use a big heavy iron fence - small humans will have an easier time making use of the gaps in the fence, and it can be made spiky so they won't have an easy time climbing or tearing it down. Or go the simple route and put spikes on the shields.\nEvery melee weapon used has to be big: daggers and short swords won't reach anything important.\nAgainst the gigantic male lions, consider using a heavy weapon like a hammer to smash their feet. Broken foot bones are as good as dead - that soldier is out of the battle. Once you hit them, drop the hammer and run, or you aren't getting away.\nBear traps/caltrops: the nature of this battle means that humans will retreat and lions will advance, the humans should take advantage of that. Bear traps are free kills (or disablings - even if the trap is removed, that lion can't get to the frontline). Caltrops, nets, and obstacles slow down the lions which means that your archers can get more shots off.", "358" ], [ "The aliens (let's just call them the Zorks) send out a gift to humanity: UNLIMITED GOLD!\nHowever, they botch the aerobraking and lithobreaking procedures by an astronomical unit. Whatever ship full of butter they sent just made an Earth-kabob, punching out the core, stopping the natural spin (thereby dooming everyone on the top to death by friction,) and then moving Earth from its orbit. Death rate: 84.2745%. A bunch of Germans, Russians, and some Nigerians remain.\nHowever, they also sent a large space station complex with it as well. Whatever's left of the Earth goes and takes the spaceships included with the main craft and moves to the space station. However, they discover that they can't get very much of the gold to the station, and furthermore - the station's life support runs on gold. Oops.\nHowever, they find a warp pad on the station. It's labeled in feet, but nobody bothers to check the math on the instruction manual: whatever language the aliens have, their word for feet is more like a millimeter. The humans accidentally end up gapping their new home in half. Death rate: 98.348572%. Only a few Germans and a Russian remain. The Russian has the wise idea to get to the shuttles, which have infinite life support. He punches the warp drive, but finds him stranded on Mars due to really slow acceleration. He is killed in the resulting planetary collapse.\nHumanity dies from a humiliation conga. If only the aliens hadn't tried to embed the ship in the planet...\nAlternatively, let's say the Zorks are like the <PERSON> from Farscape: they're highly allergic to heat. The <PERSON> are of the misconception that every form of life is allergic to life, and so they develop planetary heat shields.\nThey send these out in random directions, just hoping they hit a planet: any planet.", "99" ], [ "As luck would have it, one hits Earth. Thankfully, they did write SOLAR RADIATION CANCELLATION DEVICE on it, but Israel is dead tired of being in the sweltering sun all day. They pull the lever (against orders from Ukraine, China, Austria, Argentina and Burma) and get themselves nuked for it. Not only does the solar heat suddenly vanish, solar panels (which have become the only source of power, because ten years prior the world had just expended their last drop of oil and their last puff of natural gas) stop providing power, the world just wound up in nuclear warfare. Meanwhile, the Zorks are laughing their butts off, thinking to themselves \"they were actually going to go to war over solar radiation? Those guys must be insane!\"\nBut in another universe, the <PERSON> actually receive something from Earth: the Voyager 1 space probe. Seeing as how the people of Earth like music, they send lots of musical robots to Earth, hoping that they can help improve economic conditions by making all of the Earth fertile. Soon, every one of the robots is activated by humanity, enjoyed by humanity... and is busy paving the Earth with soil. The only water on Earth is accidentally buried under tonnes of dirty-looking dirt. They then do the same process to the Moon, except they make it water: an irrigation system. Humanity is accidentally plowed and watered. The guys on the ISS move to the Moon, building a small society. The confused Zorks watch in horror as humanity seemingly vanishes from Earth: they love to eat, and were going to send new ovens and grills to Earth once they got started. But alas, the Zorks are now drowning in cooking appliances that went unused. They issue Order 66, which is for the robots to blare \"HEY COME FARM!\" really loud. The people on the Moon last ten years before the last one dies of ear collapse.", "99" ], [ "Training\nAny reasonable 22nd century civilization is going to have robots that can inspect the hull. All you need is a camera on a robot arm, a space-traveling selfie stick (this was done on the real-world space shuttle after the Columbia disaster). But the civilization doesn't have robots that can handle every possible occurrence. If you had those robots, you wouldn't need a crew.\nSo there have to be some things that the robots can't handle. Probably not simple inspection, but repairs, upgrades, maintenance, sure. This seems to be a pretty small ship, so there's just not room for lots of robots. Humans are and always will be generalists, but maybe even 22nd century robots are specialists, like most present-day robots. For almost any given task, a robot will be better than a human - but only at that specific task. And this ship might just not have the room to carry dozens or hundreds of specialized robots.\nBefore a human can be good at any particular task, they have to practice.", "500" ], [ "Real-world astronauts (and pilots, doctors, soldiers, nuclear power inspectors...) train extensively before they go on the job - but that's not an option if your ship is spending years on a journey. Naturally the crew will train before they leave, but they still need to practice, and they'll probably cross-train each other in case somebody dies along the way.\nBut since the ship is too small to carry lots of robots, it's too small for extensive training simulators. They'll do what they can with their VR goggles, but it's just not the same. Before any crew member can be considered qualified, and periodically every so often afterward, they have to actually perform the tasks in question. And if those tasks are hull repair, engine maintenance, asteroid prospecting, or whatever else they do on their spacewalks, then sometimes you've just got to go do it.\nBut make no mistake that they would definitely keep this to a minimum. The hazards of spaceflight - especially at interstellar speeds - are tremendous. You'd likely have to carry a huge inflatable debris shield - basically a space umbrella - in case you get hit by a speck of dust. Radiation would limit the circumstances and the duration of your spacewalks. Space is not an environment conducive to human life.", "500" ], [ "Depends how specific you're talking about. If you want something like, say, \"a large brown mark on the center of the chest\", as far as I know there's no way to ensure that. Often the placement of such markings isn't even genetic - if you cloned an orange-and-white cat, their clone would be orange-and-white, but the positioning of their orange patches would be completely different, just like how identical twins have different fingerprints.\nHowever, if it would work to just have one strain have purplish marks while another has brown marks or something like that, that's readily doable.\nPossible genetic bases for distinctive markings for humans:\nPort-Wine Stains - reddish or purplish birthmarks caused by a vascular anomaly, usually located somewhere on the head or neck. Can be the result of certain genetic syndromes, but non-syndromic port-wine stains have been linked to mutations in the GNAQ gene(1). These mutations have only been reported in heterozygous form, so it's uncertain what impact they'd have if homozygous, but Basset Hounds' short-limbed dwarfism mutation is homozygous lethal and that hasn't stopped humans from turning it into the basis for a domesticated breed. If homozygous GNAQ is lethal, they'd have to have individuals with and without port-wine stains in the same families, but might be more inclined to actively show off the ones with the birthmark.\nFreckles - Small brown dots on the skin that form in response to sunlight exposure, freckles are associated with polymorphisms in the MC1R gene (2). The same alleles that cause freckles also tend to cause lighter skin tone and reddish hair. Freckles are associated with slightly higher risk of melanoma, but not a serious cause for concern. These polymorphisms are commonly seen in homozygous form, and are especially common in certain ethnic groups such as Celtic people.\nWaardenburg Syndrome - Waardenburg Syndrome is associated with a distinctive facial appearance, patchy depigmentation in hair, eyes and/or skin, going grey early, and deafness.", "762" ], [ "It's caused by MITF mutation. In heterozygotes, it can often result in no impairment in hearing, just an unusual appearance, but homozygotes have more severe symptoms(2). Still, you could conceivably have a noble house who is fine with having deaf servants breed them to be homozygous for one of the less severe mutations that causes Waardenburg Syndrome. They'd probably issue commands using sign language, and might have the bonus of being less likely to have servants passing information to their enemies. (Some slaves historically had their tongues removed for a similar purpose.)\nThere are many other potential genetic variations associated with distinctive pigmentary variations, far too many to list here. Some cause other symptoms, but anything that doesn't stop them being put to work or that only affects a minority of individuals wouldn't necessarily rule them out. After all, plenty of domestic animal breeds have been selected for features that cause impairments in their natural functioning, such as short nose syndrome in dogs or even the polled (no horns) trait in cattle (while cattle owners often prefer cattle without horns and will remove horns on breeds that grow them, in the wild cattle without horns would be at a serious disadvantage).\n1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4508108/\n2. https://www.nature.com/articles/jhg201296\n3. https://onlinelibrary.wiley.com/doi/abs/10.1002/ajmg.a.60693", "376" ], [ "No nails screws or dowel pegs have been invented. Any wooden object has to be carved from a single piece of wood. Do you have wheels? Do you need them? mud roads or slippery rocks laid out on roads make pulling skids by animal possible without moving parts like axles to make wheels. This would mean the trigger system for the bows would be impossible.\nIf you have wheels, the trees for the axles have to be huge to survive the stress, because trees on your world are flexible and weak (making regular bows possible) but small axles for triggers and other mechanical parts are too brittle. Only by making them too large to be handheld would they be possible. No one wants to build a crossbow that takes 6 horses to haul... they and it would sink into the mud.\nAnyone seeing a giant machine pulled by six horses would have time to move away before they could aim at you, making it very impractical. If it is to be used against a stationary castle, the fields surrounding the castle can be flooded, making the mud impassible for miles around, like a swamp.", "658" ], [ "The crossbow might even float away in the current. Trenches or even tree roots could slow its journey towards you. Horses could be slaughtered or poisoned in the night by spies leaving humans to pull their awkward invention themselves. The monster contraption would have to fire whole trees as arrows, and would take 3-4 hours to load in between shots. Less range than a jousting field (Is it called a \"List\"?)\nIt would become an epic tale of failure sang by the bards for generations, a combination of <PERSON> and <PERSON>'s Last Stand. \"The Tale of the Too-Big Bow\" would be told around the campfires of warriors for 30 generations, with characters making sound effects like The Three Stooges. It would become the Anti-Tale of The Trojan Horse. People would laugh at you less if you glued feathers to yourself and jumped off a cliff trying to fly. (only to be eaten by a giant bird before you hit the ground.)", "342" ], [ "Suppose, entirely for the sake of argument, that such a fictional country exists. First, it would need to have killed off all its industry - outsourced most of it to third world countries where labor is cheap. This way the large, uneducated mass wouldn't have access to the once plenty, well-paying blue collar jobs and would be kept poor. Relegated to a life in the low-wage, long hours services industry if they're uneducated.\nSecond, it would need to have placed college education at such a premium - say 40,000 - 50,000 USD a year - that it's comfortably out of range for most working-class families in the fictional country you described. This means your youth, mostly sons and daughters of the working middle-class, generally won't have access to a tertiary education. Worse even - if they do decide to go ahead with it, they're kept in bondage, in the form of student loans, for the rest of their adult lives.", "852" ], [ "This will ensure the elites, and only the elites, can send their sons and daughters to college, and therefore manage to stay educated and powerful.\nThird, it would need 'low taxes' - but only on the rich. The government is, after all, pretty much the only body capable of bridging income inequalities and redistributing wealth - so you wanna keep it as underfunded as possible. That means things like universal health care and a decent public transportation system are all also out of reach, further compounding the burden you place on your working-class citizens.\nLast, but not least: you want a fanatical, partisan media. Day in and day out, addressing the wrong problems - trying to make it all about 'personal freedoms', or guns, or foreign wars, or terrorism. Never about the clear elephant in the room which is the mounting income inequality. That would work to really drive the point home, and make sure that the rest of your citizens are kept well in the dark and alienated.\nSuch a country would be rich sure, even prosperous, but it would have no middle class, and would also be one of the most unequal countries in the developed world. Ring a bell yet?", "852" ], [ "You also need to think of the psychological side.\nA general rule of thumb is that a human army will break when it loses about a third of it's number. So even if they have 'won' 10,000 to 3000 in casualties, that might be enough for the remaining humans to break for it (and rapidly get overwhelmed).\nThere is also the impact of them not dying. You shoot them with an arrow - they keep coming. You chop an arm off - it keeps attacking. You've cut it's legs off - now it's going for your legs whilst the next two are jumping on your shield. They have no fear and no sense of injury. So your line breaks; those in the rear echelons get spooked and start running, soon it's every man for himself.\nYes, if the defenders could stand in line, methodically chop off heads and ignore their own casualties they would probably win - but battles are not like that.\nWith additions as suggested..\nLooking at various tactics:\nCavalry:\nHaving a crowd of large horses with armored knights on them is a terrifying spectacle, if it is directed at you. Of course, the zombies feel no fear. Run them through with a spear, and you've just lost your spear. Hack with a sword and you might do some damage, but taking a head requires serious skill.", "358" ], [ "Stop to fight at bay, and the mob will close in. Lose the horse, and you'll be stumbling around half-blind in heavy armor whilst zombies dogpile you. Would you charge a horde of zombies knowing that death is almost certain?\nArcher:\nLook I made a pincushion. Time to leg it now.\nCannon:\nLook I played skittles. Skittles getting back up. Tile to leg it even more..\nShieldwall:\nIn which your first rank have swords; second and third ranks have spears that protrude.\nThe whole point of the shieldwall is that it's meant to be safe, that's what allows people to go into combat (most people worry about dying, and a solid formation makes it harder to slope off), and it's hard to attack because the first attackers get skewered. But the zombies don't care - the first ones charge straight onto any spears, without dying, dragging them down. The next wave are onto the swordsmen, and even if you do kill them, sheer weight of numbers will overbear you, as above.\nThe majority of deaths in medieval battles happen in the rout, when your formation breaks up and starts to flee. Once chaos starts, the zombies have all the advantages. Every time they stab someone, break a limb, or stun an opponent they've knocked that person out of the fight; knocking them out requires serious dismemberment.", "358" ] ]

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[ [ "Validity of analysing spherical harmonics in real-space using the probability amplitude\nWhile looking up spherical harmonics (on the validity of analysing them in real-space in a transition metal crystal structure), I came across this: http://shpenkov.janmax.com/hybridizationshpenkov.pdf (published in the hardonics journal...? I haven't really come across the journal before so I'm not too sure as of the validity of its peer-review process). The author argues mainly that because \"hybridization as a mathematical mixing of qualitatively opposite properties (real and complex numbers) is physically impossible and hence unreal\", QM incorrectly describes the atomic structure.\n\"...The mixing of these complex functions, contained “real” and “imaginary” quantities, together, as it has been done in quantum mechanics, is inadmissible, just like it is impossible, e.g., to mix together the electric and magnetic fields and then to ascribe to the obtained mixture the properties inherent only in the electric field (or, vice versa, only in magnetic). Thus, hybridization as a mathematical mixing of qualitatively opposite properties is physically impossible and hence unreal. It is merely a mathematical trick used by creators of QM at the earliest stage of its building...\"\nIt is interesting because I've always accepted the <PERSON> rule without questioning how it has been derived (As so far I've been using QM mainly as a predictive tool for alloy properties in the context of alloying additions to a composition, rather than working on the theory behind it). A quick look-up of the <PERSON> rule shows that the square of the wavefunction arises from the assumption that a measurement of an observable will produce an eigenvalue as a result, and the exact perspective depends on the QM interpretation (Which I know very little about) see here.", "346" ], [ "Ignoring the hadronics journal article itself (which has managed to get me curious, and thinking), my question is then (out of curiosity) two-fold:\n1. If there is any physical meaning to the imaginary terms. And if there is - is something being missed out when one combines the terms to obtain the real orbitals?\n2. Following from that, how valid would an argument that the linear combination of real and complex numbers are \"physically impossible and hence unreal\" be? I suspect that the answer to this is in the links to the older questions (since the are complex conjugates), and I will be going through them.\nThanks!\nEdit notes 1: In the process of updating the question and reading up on the topic to update the question, I have found that similar questions have been asked before: see here and here... Following that, I have updated the question... cheers!\nEdit notes 2: Probably answering my own question, but a related answer to question 1 is found here.", "298" ], [ "Why is the screening coefficient, $\\sigma_K$, in Moseley's law only constant for high $Z$ and how can it be anything other than unity?\nIn trying to understand the screening coefficient, $\\sigma_K$ and the limitations of Moseley's law (why only valid for high $Z$) I came across a section of this lab script I found online:\nMoseley’s Law and the Determination of the Rydberg Constant\nX-rays can also be absorbed. This is essentially due to the ionization of atoms, which release an electron from an inner shell, e.g. the $K$-shell, when an x-ray photon is absorbed. The transmission of a material is defined as\n$$T=\\frac{I}{I_0}\\tag{1}$$ where $I_0$ and $I$ are the x-ray intensities incident on and transmitted through the material respectively.\nIn 1913, the English physicist <PERSON> measured the $K$-absorption edges for various elements and formulated the law that bears his name: $$\\sqrt{\\frac{1}{\\lambda_K}}=\\sqrt{R}(Z-\\sigma_K)\\tag{2}$$ where is $R$ is the Rydberg constant, $Z$ is the atomic number of the absorbing elements and $\\sigma_K$ is the screening coefficient. This equation can be brought into agreement with the predictions of <PERSON>’s model of the atom by considering the following: The nuclear charge, $Z\\cdot e$ , of an atom is partially screened from the electron ejected from the $K$-shell (through absorption of the x-ray photon) by the remaining electrons of the atomic shell.", "617" ], [ "Therefore, on average, only the charge $(Z-\\sigma_K)\\cdot e$ acts on the electron during ionization. For sufficiently large $Z$ ($\\gt \\sim 30$), $\\sigma_K$ is approximately constant and equation $(2)$ becomes linear.\nI have some conceptual questions regarding these notes/script displayed above.\nThe text above says \"remaining electrons of the atomic shell\", but this makes no sense to me. The $K$ shell consists of just 2 electrons and when one electron is ejected (via x-ray absorption) there can only be 1 electron left in that innermost $K$ shell, so why is Moseley's law not being written as $\\sqrt{\\frac{1}{\\lambda_k}}=\\sqrt{R}(Z-1)$? The reason I write this is because there is only one electron left in the $K$ shell to provide any shielding from the ejected electron (that absorbed the x-ray photon).\nThe text then goes on to say \"For sufficiently large $Z$ $(\\gt \\sim 30)$, $\\sigma_K$​ is approximately constant and equation $(2)$ becomes linear\". I have some questions regarding that quote, firstly, why restrict to high $Z$ ($\\gt 30$) to get constant $\\sigma_K$? Secondly, as mentioned before, $\\sigma_K=1$ always (at least by my logic it is) so how can it possibly be \"approximately constant\"? Lastly, what does it mean to say that \"equation $(2)$ becomes linear\"? Even if $\\sigma_K$ is a fixed numerical constant (say $\\sigma_K=1$, in the case of my argument above), that equation is anything but linear. Linear equations have the form $y= mx + c$, this $(2)$ here is quadratic in $Z$.\nI think that overall, I am misinterpreting some of the information provided to me, if anyone could help dispel my confusion with hints or tips I would be most grateful, many thanks!", "617" ], [ "No, you cannot say that there is a particular order in which the shells are filled.\nRelation between $\\mathrm{p_x,p_y,p_z}$ with $\\mathbb{m_l}$ values\nThe magentic quantum number ${m_l}$ represents the projection of the angular momentum $\\vec{l}$ of an electron in an orbital, on an axis, usually taken to be the z-axis. The orbitals, and their $\\mathrm{m_l}$ values, come from the solution of the <PERSON>'s equation for a Hydrogen atom.\nNow, the problem is, the solution for the orbitals with ${l=1}$ (i.e. p orbitals) produces one real wavefunction (corresponding to $m_l=0$), and two other complex wavefunctions (corresponding to $m_l=1$ and $m_l=-1$). If the main axis is taken to be z, then the $m_l=0$ orbital has the usual dumb-bell type shape and points in the z-direction, so it is the $\\mathrm{p_z}$ orbital. However, the complex orbitals are conjugates of each other, and if you plot the real part, they both look like donuts. (You can find more on this here and here). So the other two orbitals, let's call them $\\mathrm{p_1}$ and $\\mathrm{p_{-1}}$, do not really correspond to anything we usually see in the chemistry textbooks.\nHowever, wavefunctions themselves don't hold any physical meaning, because we cannot observe them. We can only observe things like electron energy, electron density etc. So, we can take linear combinations of the two complex orbitals to get two new real p orbitals, as long as it conserves the total energy.", "976" ], [ "However, doing this means that the new $\\mathrm{p_x}$ and $\\mathrm{p_y}$ orbitals are no longer eigenfunctions of the $\\hat{L_z}$ operator (i.e. they have no well defined angular momentum along the z-axis, so no well defined $m_l$ value). In most cases angular momentum is not really important, so we can safely use $\\mathrm{p_x}$ and $\\mathrm{p_y}$.\nI suspect that there is a similar case with the d orbitals as well.\nWhich orbital is filled in first?\nInside one shell (e.g. 2p) the electrons are indistinguishable, so it is not possible to say which orbital is occupied by which electron. However, if a shell is not completely filled, i.e. there are unpaired electrons, then there would be an total orbital angular momentum and total spin angular momentum coming from all of those electrons combined. It is possible to identify states which have different angular momenta, as they have different energies. This forms the basis of the coupling schemes (LS coupling or jj coupling). However, you still cannot say exactly which electrons are residing in orbitals with which $m_l$ values, because multiple arrangements (microstates) can contribute to the same energy level (term).", "976" ], [ "You can't just get it from the atomic properties, the electronic properties of a metal are dominated by \"solid state\"-type considerations, for instance, the fact that electrons live in a band structure rather than something more akin to the usual discrete levels that one learns about in QM 1.\nThankfully, <PERSON> and <PERSON>'s classic book has a long discussion on the work function in chapter 18.\nTheir formula is $W=-\\epsilon_F+W_s$, where $\\epsilon_F$ is the Fermi energy, a quantity determined by the density of electrons and the properties of the crystal lattice of the metal; you can work out reasonable approximations to this for alkali metals by using the free electron approximation. $W_s$ is a quantity related to surface effects; for this term <PERSON> and <PERSON> give a model with a dipole moment per unit area of $P$, so that $W_s=-4\\pi e P$.\nI'm not sure whether you can really get \"within a few percent\" with such crude techniques, but it's certainly something that's calculable. In particular, getting a good approximation comes down to two things, 1) getting a handle on the band structure of the metal so that you can calculate $\\epsilon_F$ accurately 2) having a good model for the surface of the metal.\nThere's a wrinkle here about how $\\epsilon_F$ is defined.", "28" ], [ "One can't just use the usual expression $\\epsilon_F=\\hbar^2k_F^2/2m$ as one needs to add in a term corresponding to the electrostatic energy of the ions, something like the Madelung constants.\nAgain, I recommend the book of <PERSON> and <PERSON> for this (and any other just-beyond-basic questions you might have about thinking about electrons in metals and semiconductors).\nJust out of curiosity, I dug into the literature a little bit to see what researchers have done.\nIn 1971, <PERSON> and <PERSON> were able to get work functions of simple metals to about 5% and noble metals to 15%. I think it would be possible to reproduce these calculations today quite easily.\nA more recent paper (2005) by <PERSON>, <PERSON>, and <PERSON> uses all-electron first principles calculations, as opposed to the more empirical fitted pseudopotential calculation that <PERSON> and <PERSON> used. My impression from skimming the data is that they only get marginal agreement with experiment; in particular, I noticed that the experimental values seem to have quite a bit of variance in them, consistent with the fact that work function is strongly dependent on surface properties, which are hard to get consistent.\nFor example, for Aluminum along the 1 1 1 crystal plane, their calculations yield 4.21eV, compared to experimental values of 4.48, 4.24 and 4.33.\nBy comparison, <PERSON> and <PERSON>'s 1979 calculation gave 4.05 eV and they quoted an experimental value of 4.19 eV.\nApparently the last big review on calculating work functions of metals is this one by <PERSON> et al from 1979. I didn't read it though.", "1020" ], [ "What does the concept of \"free electron\" mean in the context of band theory?\nOften when conductivity is explained through band theory, the term \"free\" tends to crop up. As an example, I often come across descriptions of the valence band as a highest filled set of states occupied by electrons bound to their specific atoms; raising them to the conduction band supposedly \"frees\" them so that they can move freely in the metal, thereby enabling them to contribute to a current when an electric field is applied.", "927" ], [ "In fact, in my introductory solid-state physics book, the additional electron contributed by a donor in a doped semiconductor is referred to as \"loosely bound\" to the donor ion, requiring a push into the conduction band to break free and become a charge carrier.\nAt the same time, I was also given to understand that the electrons of a valence band do not contribute to a current when there is an electric field, because their respective velocities balance each other out perfectly; there is no net velocity and hence no net movement. Raising an electron into the conduction band essentially means creating a hole in the valence band so that the electrons can now redistribute (in k-space) and thereby achieve a non-zero net velocity.\nBut according to this latter statement, the electrons in the valence band should contribute to a current across the metal when an electric field is applied.\nA) How then can the valence band electrons be bound to a specific atom, as the former statement claims, if they are simultaneously capable of acting as charge carriers? Also, how then can the donor electron - which occupies an energy state above the valence band - be \"loosely bound\" to the donor atom, when the electrons below aren't?\nB) Assume that we raise the temperature enough (without the metal somehow disintegrating) so that some electrons from even the lowest band leave for higher energy bands. Will the holes that are left behind in this lowest band also mean that the remaining electrons in this band can carry charge, similar to how the electrons in the valence band with holes were able to carry charge?\nI'll be grateful for anything that can help me clear up this mess!", "531" ], [ "Without going into a long discussion about what the wave function is, I will try to briefly answer your questions:\n1) For atoms, the (approximate) solution to $\\Psi$ is the product of two functions:\n* the radial components (distance from the nucleus)\n* the angular/spherical components (behavior going around the nucleus, like latitude and longitude)\n2) Since the radial components of each component extend quite far, decaying to zero only at infinity, it would be very difficult to make a plot of the 3D object on a 2D surface that does not cover up the features that would be nearer the nucleus (further from eye), without using varying degrees of transparency.\nThe spherical component is usually solved analytically using complex numbers (i.e. a+b*i) but they can be transformed into real values by linear combinations. So, instead of two \"channels\" for real/imaginary, we can use only one \"channel\" (real) for each function, 1s, 3dxy, etc. Often, these are colored so that if the sign of the real function is positive, it is e.g. red, otherwise, e.g. blue.\nA second feature of these types of graphics is called the \"isosurface\"--which means, plot only if the value of the function is equal to a chosen value.", "586" ], [ "Sometimes the chosen value is taken to be \"90% of the corresponding electron density contribution from this atomic orbital is enclosed\" (which, b.t.w. is $\\Psi^ \\Psi$ or simply $\\Psi^2$. Though $\\Psi$ may be real/complex/negative/positive valued (hence need all sorts of colors and \"channels\" to represent it) the electron density is positive and real*. This is very important, as complex quantities are not observable, but are rather mathematical constructs (vehicles) for arriving at things that are actually observable, such as the electron density.\nBut practically speaking, in order to see certain features like the doughnut in $dz^2$, people play a little fast and loose with precisely what the value of the isosurface is.\nThe shading on the surfaces that you have provided could be misinterpreted, because the colors do not correspond in any way to the value of the function being plotted, but rather seem to be an aid to the volumetric rendering of an isosurface that has already been set to either the absolute value or the square of the atomic orbital.\nFinally, note that in your center drawing, which adds all of the individual atomic orbitals, that you are beginning to form a sphere. It had better, as atoms are, in fact, spherical!${}^{\\dagger}$ The formal name of the functions are spherical harmonics, and the set of e.g. $p_x$, $p_y$, $p_z$ or the five $d$'s taken together form a spherical shape.\n${}^{\\dagger}$ assuming the nuclear quadrupole is zero", "976" ], [ "The EPR experiment measures the interaction of unpaired spin density ($\\rho(\\alpha)$) at the nuclei. This is quantified by an equation called the Fermi contact interaction.\nIf you have some prior knowledge of \"where to put the dot\" in your structure (highly localized), then generally you can assume that the EPR pattern is split most by that nucleus. Splitting patterns are determined by standard rules in accord with the <PERSON> effect.\nThe nucleus must have a non-zero nuclear spin to be observable. Certain nuclei such as hydrogen-1 and many transition metals have spin. It is very common that isotopic impurities (e.g. carbon-13) appear though the most prevalent isotope is EPR-silent.\n(There are other complications, such as nuclear quadrupole moment and broadening due to exchange of chemical sites.)\nAn additional issue is that the spin density is generally spread over the molecule, and interacts with multiple nuclei.", "469" ], [ "It turns out to be easier to measure the spectrum, and then rationalize it given the particular structure and nuclear composition.\nAccurate prediction of EPR spectra is a rather difficult problem, as quantum chemical calculations generally don't emphasize basis function placement at the nucleus, as they tend to focus on the \"valence\" and not the cusp-like nature of the radial distribution. (Here, Slater-type orbitals would be better in principle than Gaussian-type, but STOs of sufficient number and of high-enough quality of Hamiltonian are virtually impossible). Finally, solvent and powder effects can render the gas-phase ab initio calculations virtually irrelevant.\nEPR simulation/interpretation of fine structure is much more difficult than NMR spectra, because in NMR spectra, one has the chemical shift to conveniently move splitting patterns out of the way. In EPR, the splittings are often \"piled\" on top of each other, and make it necessary to use computer simulation to obtain precise fits.\nIn your specific example, I would identify the nuclei with spin (probably Cu, certainly phosphorus-31, and then hydrogen-1). Then, identify where you think the unpaired density will be, and then take the nuclear spin + 1 and that will be the \"guesstimated\" isotropic spectrum. The pattern will follow some variant <PERSON>'s triangle if I=1/2, otherwise, you have to figure it out by writing out the number of possible configurations.\nEdit: I have not even started on the characteristics of triplet spectra, as here the electrons interact. One thing you can hope for is that all of your electrons are paired (singlet), and so it's EPR silent.", "969" ], [ "Unit cell structure of ionic crystal\nI have a question about the structure of an LiH unit cell, and while this is related to a homework problem, it isn't the problem itself, I'm just looking for conceptual understanding. I've already found that there should be 4 Li+ ions and 4 H- ions in one unit cell. However, I am struggling with how they will be arranged. Because the number of LiH molecules is 4, I am fairly certain that the structure intended for this problem is face-centered cubic lattice. This is where my conflict begins. In my class we have had the face-centered cubic unit cell described as (for one element) an atom at each corner and an atom in each side. From this arrangement we get (1/8)8 + (1/2)6 = 4 atoms.", "793" ], [ "Now, I've seen a description online of the face-centered cubic structure for NaCl as \"We can think of this as chloride ions forming an FCC cell, with sodium ions located in the octahedral holes in the middle of the cell edges and in the center of the cell. The sodium and chloride ions touch each other along the cell edges. The unit cell contains four sodium ions and four chloride ions, giving the 1:1 stoichiometry required by the formula, NaCl\" (Chemistry LibreTexts). For me this makes a certain amount of sense, because this would give 4 cations when you use the same counting principle as before. However, I've seen multiple diagrams online that contradict this, such as: https://images.app.goo.gl/CGAsc4xAJM39tMgi8. This seems to claim that the center image is the unit cell, and while it does have 4 of each ion \"on\" it, it does not seem to fulfill the same structure as the aforementioned unit cell suggestion. Is the problem here just that they are showing 1/8th of the full unit cell for simplicity? If not, I am even more confused.\nThank you for reading this extraordinarily long question for what could be a very simple answer! And please don't roast me too hard, I've never posted here before.", "870" ] ]

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[ [ "2-Tier Wooden Plant Stand\nIntroduction: 2-Tier Wooden Plant Stand\nWith a number of plant pots on the floor I felt it was time for a little decluttering and what better way to get them off the floor by building a multi tier wooden stand.\nThe stand is made using only wood (planks & blocks), and screws; no brackets or other supports are required.\nSupplies\nWooden Decking planks 2.4m(L) x 120mm(W) x 24mm(H) - Qty 6\nTimber Block 1.8m(L) x 50mm(W) x 47mm (T) - Qty 5\nStainless Steel Screws - 4mm x 40mm - Qty 78 (Brass as an alternative)\nAll materials were purchased from the local DIY store.\nTools\nCombination square\nPencil\nTape Measure\nDrill - (Manual or Powered)\n3mm drill bit\nSaw - (Manual or Powered)\nScrewdrivers\nHammer\nClamps\nKnow your tools and follow the recommended operational procedures and be sure to wear the appropriate PPE.\nStep 1: Design\nThe initial design was created in BlocksCAD before commiting to a physical build.\nStep 2: Lower Shelf Planks\nUsing a standard 2.4m long plank measure 1.2m with a tape measure and at this mark with a combination square draw a line along the width.\nCut along this line with the saw to create 2 equal lengths.\nThis process needs to be repeated creating a total of 5 equal length planks.\nOne of these planks will be set horizontally at the rear.\nTherefore, it will require two cutouts to accomodate the rear legs.\nAt the rear back corner of the plank mark a 50cm x 50xm square.\nCut the square out with the saw.\nRepeat the process at the opposite end of the plank in the rear corner.\nStep 3: Lower Shelf Sides\nUsing the remaining 1.2m from the previous process.\nMeasure with a tape 45cm and at this mark with a combination square draw a line along the width.\nCut along this line with the saw.\nMeasure and cut a second 45cm length.\nStep 4: Lower Shelf Retainers\nBlock timber is used in creating the retainers.\nUsing a standard 1.8m length measure 1.1m with a tape measure and at this mark with a combination square draw a line along the width.\nCut along this line with the saw.\nThis process needs to be repeated with another 1.8m length creating a total of 2 equal lengths.\nUsing one of the 70cm remnant cut two 30cm lengths.\nStep 5: Upper Shelf Planks\nUsing a standard 2.4m long plank measure 1.2m with a tape measure and at this mark with a combination square draw a line along the width.\nCut along this line with the saw to create 2 equal lengths.\nThis process needs to be repeated creating a total of 4 equal length planks.\nStep 6: Upper Shelf Sides\nUsing a standard 2.4m long plank measure 33cm with a tape measure and at this mark with a combination square draw a line along the width.\nCut along this line with the saw.\nMeasure and cut a second 33cm length.\nStep 7: Upper Shelf Retainers\nBlock timber is used in creating the retainers.\nUsing a standard 1.8m length measure 1.1m with a tape measure and at this mark with a combination square draw a line along the width.\nCut along this line with the saw.\nThis process needs to be repeated with another 1.8m length creating a total of 2 equal lengths of 1.1m.\nUsing one of the 70cm lengths cut two 18cm lengths.\nStep 8: Vertical Supports\nBlock timber is used to create the vertical supports.\nUsing one of the 70cm remnants measure and cut a 49cm length.\nTake another 70cm remnant measure and cut another 49cm length.\nThese will form the middle legs.\nThe front legs will be the renmants of the middle legs at 21cm\nUsing a standard 1.8m length measure 70cm with a tape measure and at this mark with a combination square draw a line along the width.\nCut along this line with the saw.\nThis process needs to be repeated creating a total of 2 equal lengths.\nThese will form the rear legs.\nStep 9: Pre Treatment\nIf the wood has not been pretreated to protect it from the elements, rot or pests; now would be a good time to do this before assembly. The ends are particularly prone to degradation.\nI recommend soaking the ends in a bucket filled with a suitable preservative.\nLeave overnight.\nFlip over and again soak overnight.", "401" ], [ "Wooden Box Planter\nIntroduction: Wooden Box Planter\nHaving recently built a new fence around the garden I had plenty of offcuts of wood.\nNot wanting to throw them away, I had to make use of them in some way.\nSo a raised box on legs for plants seemed a suitable use for the offcuts.\nSupplies\nDecking board 1.8M x 120mm x 24mm\nStick Timber 1.8M x 50mm x 50mm\nExternal wood screws 5mm x 50mm\nSaw\n3mm Drill bit\nDrill\nScrewdriver.\nTri square\nRuler\nTape Measure\nMarker/Pencil\nG clamps/Adjustable clamps\nStep 1: Design\nThe wooden box planter is designed in Tinkercad using Code blocks at 1/10 scale.\nThe design is available at Elevated_box_planter | Tinkercad\nStep 2: Box Elements\nUsing two decking planks, measure 4 lengths of 56cm and cut the decking, these will form the front and back.\nCut 8 x 24 cm lengths these will form the sides and the base.\nCut the timber stick to create two length of 51cm, these will form the support for the base.\nStep 3: Base Corners\nTake two of the base boards and mark two 50mm x 50mm squares on one long side of each board aligning one with the top edge and one with the bottom edge.\nCut these four squares from the two boards these will form the entry points for the legs.\nAlign the short end of the base support with the inset vertical edge of the base corner board.\nAlign all 4 corners to form a rectangle and in each of these corners insert a screw.\nPrior to inserting the screws drill a pilot hole with the 3mm drill bit, this will prevent the wood splitting when the screw is inserted.\nStep 4: Long Sides\nPosition the long sides front and back and attach with 2 screws per support block.\nThe screws should be positioned so as to enter the midline of the support block at ~25mm\nStep 5: Short Sides\nThe four offcuts from the support are used to enable the short sides to be fitted by first attaching them to the outer edge of the corner supports.\nOnce these are attached the sides can be screwed in place.\nStep 6: Level One\nThe long and short sides attached so far are only the first level as another row is required to complete the box.\nThe other four sides are attached to the legs.\nStep 7: Attaching Legs\nThe legs are inserted into the corner openings previously created.\nThey are inserted so as to have 30cm visible below the bottom of the box.\nOnce measured mark a line in case the leg moves.\nAttach the leg to the first row by the corner of the long and short sides with 2 vertically aligned screws, repeat for all four legs.\nThe screws should be positioned so as to enter the midline of the support block at ~25mm\nStep 8: Level Two\nOnce the legs are secure fit the long and short sides by screwing these to the legs with 2 vertically aligned screws.\nThe screws should be positioned so as to enter the midline of the support block at ~25mm\nA gap of 24mm is created by using a short piece of decking board as a spacer between the first and second level.\nOnce the sides are fitted the spacer can be removed.\nStep 9: Finally\nApply preservative, stain and or paint as required then include plants in pots or grow bags.", "401" ], [ "Utility Receptacle\nIntroduction: Utility Receptacle\nMade from the remnants of a previous project is a Utility Receptacle which has a multitude of uses around the home.\nAs a receptical for another container such as a flower pot, water holder for cut flowers, table lamp or hanging lantern.\nIts made of a combination of wood, acrylic and stainless steel.\nThe wooden elements being the remnants of the material stock used in the following projects:\nMass Driver : 11 Steps (with Pictures) - Instructables\nWooden Bouquet : 6 Steps (with Pictures) - Instructables\nTensegrity Shelf : 7 Steps (with Pictures) - Instructables\nRecycle Flower : 7 Steps (with Pictures) - Instructables\nOffcut Stack Birdhouse : 8 Steps (with Pictures) - Instructables\nWooden Box Planter : 9 Steps (with Pictures) - Instructables\nSupplies\nMaterials\nWooden Decking remnants ( ~120mm x 240mm x 25mm) - Qty 2\nAcrylic lollipop sticks (4mm diameter x 150mm long) - Qty 12\nStainless steel rod (6mm diameter) - 8 pieces ( Qty 4 - 75mm long & Qty 4 - 150mm long)\nMasking tape (50mm wide)\nLinks only given as a possible source and reference to materials used. You may have your own alternative supplier.\nTools\nDrill\n6mm wood drill bit\n4mm wood drill bit\n1mm drill bit\n95mm hole saw\n60mm hole saw\nHack saw\nFlat file\nSanding paper\nRuler\nMarker\nVice\nAdjustable Clamps\nCompass/dividers\nProtractor\nSteel ruler\nList of tools is not exhaustive and given as a guide, not all tools may be required and may be substituted for alternatives.\nEnsure you are familiar with the use of any tools and apply suitable safety requirements and PPE.\nStep 1: Design\nThe design has been created in BlocksCAD and shows the final assembly with colour coding to identify the various elements.\nAll the code blocks are separated and grouped by the appropriate elements allowing these to be viewed individually.\nThis enables the two rings and base to be 3D printed if required.\nStep 2: Rings\nBoth rings were cut out of one of the remnants.\nA sacrifical renmant is placed on the work surface and pegs are placed either side to prevent slippage.\nThe piece to be cut is placed on to the sacrificial renmant and clamped to prevent movement.\nAn adjustable hole saw with two blades (95mm & 60mm), is fitted into the drill.\nProceed to cut out the rings, charring may be evident on the flat surface due to friction when the full depth of the wood has been penertrated when the ring is liberated from the main body.\nCharring is not too much of an issue as it will be removed during the sanding process.\nRepeat the process for the second ring.\nStep 3: Base\nThe base is cut from another remnant.\nA sacrifical renmant is placed on the work surface and pegs are placed either side to prevent slippage.\nThe piece to be cut is placed on to the sacrificial renmant and clamped to prevent movement.\nIn this case only one saw blade (95mm), is used; additionally the centre bit was only allowed to penetrate half way into the piece.\nThe resulting hole would sit on the underside of the finished vase and be out of sight negating filling.\nProceed to cut out the base, charring may be evident on the flat surface due to friction when the full depth of the wood has been penertrated when the base is liberated from the main body.\nCharring is not too much of an issue as it will be removed during the sanding process.\nWhen part way through the piece I removed the hole saw body from the centre drill bit placed a spacer made from a piece of 15mm copper pipe on the centre drill bit then put the hole saw body back in place.\nIf using a hand drill run the drill a a slower speed to prevent that possibility of the blade skipping out of the cut.\nAlternatively, leaving the centre bit in the default position will result in a small hole right through the body of the base which could be left as is or filled in. The decision is yours.\nStep 4: Sanding\nThe ridges in the pieces are to be removed by sanding to create a smooth surface.\nThis can be accomplished mechanically or by hand.\nOnce complete the next stage is template marking.\nStep 5: Template Marking\nEach of the resulting pieces needs to be marked up to enable holes to be drilled for the supporting pillars.\nThe centre ring is used as a template which is used to mark up the other ring and the base.", "401" ], [ "Drink Holder From Cord and Wood\nIntroduction: Drink Holder From Cord and Wood\nWith warmer weather the tendency is to stay outside more being acitive or just relaxing.\nThinking of relaxing, sat outside in the garden with a cooling drink got me thinking of my next project.\nI have a drink but were do I put it, on the floor with the possibility of knocking it over trying to reach for it or kick it over with my feet.\nA table is a good spot but in my case its not situated next to the bench due to space constraints.\nTherefore, I needed another option and hence the drink holder was created.\nSupplies\nWood decking 120mm (W) X 20mm (H) X 230mm (L) or similar size plane sawn wood.\nPlywood 9mm thick (greater than 60mm (W) x 60mm (L)) or similar size perspex/metal washer.\nParacord 2mm diameter x ~6m length\n95mm hole saw\n60mm hole saw\n3mm drill bit\nOptional 10mm drill bit (if the bit in the hole saw is <10mm)\nScrews 40mm x 4mm - Qty 2\n25mm panel pins - Qty 8\nWire Staples 5mm x 15mm - Qty 8\nDrill\nClaw Hammer\nPencil/Marker\nSandpaper\nProtractor\nDrawing Compass\nCombination square\nScrewdriver, nail, skewer or crochet needle.\nPaint, varnish, stain, oil or wax\nKnow your tools and follow the recommended operational procedures and be sure to wear the appropriate PPE\nStep 1: Base\nThe base of the drink holder is made from a circle of plywood cut from a larger piece using a 60mm diameter hole saw attached to the drill.\nThis helps to maintain the required diameter of the net and provides a stable platform for the beverage.\nThe centre hole needs to be ~10mm in diameter, if necessary redrill the hole with a 10mm drill bit if the bit in the hole saw is smaller.\nWith sandpaper remove any rough edges.\nApply suitable protection against moisture ingress, be it paint, varnish, oil or wax.\nStep 2: Top\nThe top of the drink holder which is the main supporting element is made from a piece of wooden decking.\nIn this case, two separate 95mm holes are cut side by side, one to hold the drink and one to facilitate different mounting options. One option being to pass this up the leg and fix at a 45 degree angle. Although fixing behind the leg at 90 degrees was less intrusive and selected as the final position.\nFind the centre of the decking (115mm, 60mm).\nMeasure 55mm to the left on the horizontal.\nUsing a protractor, compass and ruler at this centre create 8 segments each of 45 degrees, extend the segment lines beyond the diameter of the 95mm hole to be cut.\nDraw a 105mm diameter circle to cross the segment lines the intersections will act as guides for the panel pins/nails.\nCut the 95mm hole.\nMeasure 55mm to the right on the horizontal and cut another 95mm hole.\nWith sandpaper remove any rough edges.\nAt each of the intersections hammer into place a panel pin/nail, you need to be able to remove these later therefore do not insert them too deeply.\nStep 3: Tie the Base\nThis and the following processes will make use of the paracord which will be one continuous length from start to finish.\nCreate a slip knot and thread the loop through the hole in the 60mm base disc.\nWith a loop that is as large as the disc push the disc through this loop and push the loop towards the knot and pull tight.\nStep 4: Suspend the Base\nThis part of the process requires centring the base and and tensioning which results in it being suspended between the pins.\nThe process consists of a series of loop.\nPosition the base in the centre of the ring.\nLoop the long end of the cord round the first pin (in this case at the 12 o'clock position).\nForm a loose loop and push the loop through the central hole in the base.\nPull this so it is able to extend over the next pin (at the 1 o'clock position).\nWith the long end of the cord extending from the centre hole, pass this under the 1 o'clock loop.\nTry to keep the cord flat against the inner hole to prevent the hole becoming constricted.\nIf the hole becomes constricted push a skewer, nail or cross head screwdriver into it to flatten the cord and widen the hole.\nPull the cords to remove the slack such that the two loops at 12 & 1 o'clock are held tight but with enough slack to maintain the base centrally.", "401" ], [ "Tensegrity Lampshade\nIntroduction: Tensegrity Lampshade\nThis is the fourth in a series of Tensegrity projects having previously made projects with 3D printing and wood, this time I make use of Acrylic sheet. Previous projects include: Tensegrity Planter & Tensegrity Shelf\nThis would employ Tensegrity at multiple points on multiple levels to create a Lampshade.\nUsing eight C suspensions over two levels with shared wires over the two levels to reduce the number of tensioning wires.\nSupplies\nAcrylic sheet White: 5mm x 160mm x 160mm - Qty 2\nAcrylic sheet Black: 5mm x 160mm x 160mm\nAcrylic sheet Clear: 5mm x 60mm x 60mm\nAcrylic sheet source.\nAcrylic Clear Tube: 25mm(Outer dia.) x 21mm(Inner dia.) x 155mm(L)\nBrass Wire: 0.4mm diameter\nM3 Grub Screws: 3mm - Qty 24\nM3 bolts: 16mm - Qty 3\nM2 bolts: 4mm - Qty 16\nM2 bolts: 20mm - Qty 12\nChrome plated copper pipe 50mm dia. x 155mm (L)\nPlastic plant pot 100mm dia.", "31" ], [ "x 80mm (H)\nReady mix cement\nCork mat or felt\nAcrylic Adhesive\nMulti purpose Adhesive\nNo affiliation to any of the suppliers used in this project, feel free to use your preferred suppliers and substitute the elements were appropriate to your own preference or subject to supply.\nMany of these items are also available at DIY stores.\nTools\nPliers\nCutters\nHole saw 54mm\nHole saw 50mm\nHole saw 38mm\nHole saw 32mm\nSaw\nCombination square\nMarker/Scribe\nCompass\nScrew drivers\nAllen keys\nDrill\n2mm drill bit\n3mm drill bit\n15mm masonary drill\nClamps\nFile\nSanding paper\nCircular bubble spirit level\nKnow your tools and follow the recommended operational procedures and be sure to wear the appropriate PPE.\nStep 1: Cutting the Arcs\nUsing black Acrylic sheet.\nIdentify the centre of the circle to be cut in the Acrylic sheet and draw a horizontal or vertical line to create 2 equal segments.\nClamp the Acrylic sheet to a sacreficial piece of wood and secure in place.\nUsing a 38mm hole saw cut out a circle.\nWith a 54mm hole saw align the centre drill bit into the hole made in the wood by the previous process and carefully cut out an Acrylic ring ring.\nRepeat this process for a total of 4 rings\nUsing a saw cut each ring in half along the remnants of the line.\nRepeat this process using white Acrylic sheet.\nThis will result in 8 black and 8 white arcs.\nNote:\nFrom experience I have found that Acrylic sheets have different thermal properties which effect the cutting.\nRunning the saw at very high speeds can result in the Acrylic sheet melting which can clog and trap the saw.\nStep 2: Drilling the Arcs\nEach arc requires two holes to be drilled in the perimeter edge close to the vertical cut.\nMeasure 2.5mm in from the vertical edge and mark with a line across the perimeter.\nMeasure 2.5mm in on the perimeter edge and draw a line along the perimeter.\nMark at the intersection of the cross.\nSupporting the arc in a vice or clamp drill a 2mm hole through the outer perimeter to exit at the inner perimeter.\nRepeat at the other end of the arc.\nPerform this process on all 16 arcs.\nSmooth any rough edges with sanding paper or a file.\nNote.\nDo not apply too much pressure when drilling the arcs to prevent damage.\nStep 3: Platform Markup\nRefer to the diagram which shows the relationship between the outer platform and the inner platform which are aligned to enable coincident holes. Although the radius of the outer platform is 63mm whilst the radius of the inner platform is 83mm.\nWith a 5mm Acrylic sheet of 160mm x 160mm.\nThe measurements on one platform are used to create the alignment for the other platforms.\nA total of 3 platforms are required.\nThe process is simplified by stacking and clamping the three platforms and using the top platform for drill alignment.\nIn the finished form the platforms are stacked with the following colour pattern of White, Black & White.\nBegin first by marking out the first platform.\nMark the centre of the sheet. (80mm, 80mm)\nAt the centre with a compass draw a circle with a radius of 63mm.", "819" ], [ "Offcut Stack Birdhouse\nIntroduction: Offcut Stack Birdhouse\nA bird house with a difference that does not conform to the standard convention of four walls and a roof.\nI would make it out of offcuts stacked on top of each other with a central hole.\nThe offcuts are bolted together with threaded rod and the central hole capped at both ends to make a box with an access hole in the front.\nAll the pieces that make up the house are all exactly the same shape and size, meaning no odd shapes to contend with.\nIts simply a case of drilling a large central hole in all but 2 pieces and aligning them vertically.\nSupplies\nDecking boards H 9.5\" (24cm) x L 9.25\" (23.5cm) x W 4.75\" (12cm) - Qty 10\nWood Screws 5mm x 50mm - Qty 2\nM8 nuts - Qty 2\nM8 T nuts - Qty 2\nM8 Threaded Bar 10.5\" (26.7cm) - Qty 2\nM8 1\" (25mm) plain washers - Qty 2\nM6 1.62 (45mm) bolt\nM6 plain washer\nM6 nut\n3mm drill\n8mm drill\n102mm Holesaw\n32mm Holesaw\nCylinder pull latch\n22mm flat drill\nHammer/Mallet\nStep 1: Design\nThe bird house is designed for small birds such as chickadees and tits\nThe design has been created in Tinkercad and can be found here: Offcut_Birdhouse\nThe bird type defines certain design features.\nMost designs are square and as such this defines a floor size of 4\"x4\" (10.16cm x 10.16cm), this design 2\" (5.08cm) radius.\nA height between 6\"-10\" (15.42cm-25.4cm), this design is 9.52\" (24cm)\nHole diameter 1.125\" (2.86cm), this design as specified\nHole above floor 8\"-10\" (20.32cm-25.4cm), this design 7.5\"(19cm)\nBox above ground 6'-15' (1.82m-4.6m)\nFurther details can be found at Birdwatching Bliss*\n*Not affiliated to this site in anyway and you may have your own preference.*\nStep 2: Cut the Main Holes\nThe offcuts consisted of 10 rectangles of 24mm x120mm cut to 23.5cm.\nI already had the offcuts available but if not these can be cut from a full size length which is 1.8M long.\nIdentify the centre (60mm x 11.75cm), and mark.\nFit a sacrificial plank beneath the plank to be drilled to protect the work area and clamp the plank to be drilled above it.\nWith a 102mm hole cutter drill out a hole in each of the eight planks.\nStep 3: Stacking the Blocks\nMark the block at (60mm x 45mm), from the end, do this at both ends and drill 2 x 6mm holes.\nDo this on 8 of the planks.\nThe 9th plank is the bottom of the house and blocks the end of the hole created by the stack.\nTake the 9th plank and drill 2 x 8mm holes at (60mm x 45mm), from each end.\nThese holes are to accommodate the T-nuts, tap them in with a hammer to force the prongs in to the wood to lock them in place.\nStack all nine blocks together and fit the 6mm threaded bar of length 27cm through both holes from the bottom and screw into the T-nuts.\nOnce these are attached fit a washer and nut on the bottom end and tighten.\nThis now holds the stack together.\nStep 4: Fitting the Lid\nAlign the lid with the top of the main stock.\nMark at 60mm x 25mm and drill 3mm holes at both ends of the block in to the lid and through to the block below.\nThese hole will hold the lid in place.\nThen with a 22mm flat bit drill to a ~5mm depth using the centres of the threaded bar as a marker. These holes are to accommodate the top of the T-nut.\nDrill two 8mm by 10mm deep holes coincident with the centres of the 22mm diameter holes.\nTurn the plank over and align with the tops of the threaded bar it should fit flush with the previous plank.\nFit two 5mm x 50mm screws to hold the lid in place.\nStep 5: Entrance\nMark a vertical line along the centre of the stack.", "401" ], [ "Recycle Flower\nIntroduction: Recycle Flower\nHaving just completed a project that made use of left over materials Offcut-Stack-Birdhouse, even the making of that project created its fair share of offcuts. In fact most projects result in left over material.\nBut rather than throwing all the left overs away if there is sufficient material its retained for another possible project when something comes to mind.\nIn this case I had a number of circular leftovers, in keeping with the most recent projects and the summer weather conditions, something for the garden. At the same time all projects do not have to involve a lot of time.\nA recycle flower to decorate the shed door would be created.\nSupplies\nCircular wooden circles created with ~102mm Holesaw - Qty 7\nScrews 20mm x 3mm - Qty 12\nL-Brackets - Qty 6\n2mm drill bit\nPaint, any suitable colours.\nTri Square\nRuler\nPencil\nStep 1: Design\nThe design is visualised in BlocksCAD.\nConsisting of seven offcut circles, one in the centre and six placed around the the perimeter.\nThis was not intended to represent a specific type of flower but more an artistic representation of a flower form.\nBut most closely resembles a Star-shaped (stellate), radiating from a common centre.\nStep 2: Preparation\nTake the previously cut circles and paint with quick drying undercoat paint and allow to dry.\nStep 3: Arrange for Drilling\nOnce the circles have dried, arrange into the required flower pattern and position the L-brackets.\nMark the position of the holes in the petals.\nThe central part (pistil), needs to have the holes drilled around the edge.\nWith a ruler draw a line between two directly oppositely placed L-brackets passing through the centre of each bracket and the centre of the wooden circle.\nThis will result in six equal segments..\nWith a tri square extend each line along the edge.\nPosition the L-bracket along the edge with its hole centrally aligned with the edge line and mark the hole.\nEach petal is to have one hole on the flat side and the pistil will have six holes around the edge.\nStep 4: Drill the Holes\nClamp the circles on a sacrificial board to protect the work surface prior to drilling.\nWith a 2mm drill bit make the holes, when drilling the petals make sure not to go through to the other side.\nIn this case the wood is 24mm thick and the screws 20mm long.\nDrill six 2mm diameter holes (sufficiently deep to accommodate the screw), around the edge of the circular piece that will be the centre of the flower.\nStep 5: Fit the Brackets\nDepending on the colour, the pattern and the type of paint, you may wish to paint the elements in your chosen colour scheme.\nHowever, its preferable to paint before final assembly which will allow painting of all areas without unintended transference of colours.\nIf the flower will be viewed only from one side, then the brackets need not be painted.\nWith the screws attach the L-brackets around the edge of the central part (pistil), all orientated the same way.\nThen attach each petal to an L-bracket, this completes the build.\nStep 6: Position\nUsing the hole that already exists in the central part of the flower insert a screw or nail and attach it to a suitable surface (shed door for example), to fix the flower in place.\nFixing options are to fit two hooks, wires or strings through the holes in the upper two petals and hang from an extended right angle bracket to display both sides in a similar way to a sign.\nAlternatively, place on a ledge or shelf.\nStep 7: Finally\nAll done.\nTime to admire your work.", "401" ], [ "My Favourite Joinery Method for Plywood, MDF & OSB\nIntroduction: My Favourite Joinery Method for Plywood, MDF & OSB\nSheet material such as Plywood, MDF and OSB are fantastic to work with. They are really versatile and easily available at your local DIY hardware store. The awkwardness comes when it's time to decide what joinery method to use. So in this post I'm going to show you my favourite joinery method for sheet material.\nI've always liked the simple solution to problems and I think this joinery method couldn't get any simpler. It uses a router. a slot cutting router bit and some pieces of 6mm MDF.\nSupplies\nTools & Materials Used:\n* Router\n* Slot Cutting Router Bit\n* 6mm MDF\n* Wood Glue\nStep 1: The Star of the Show\nThe star of the show is the slot cutting router bit itself. The bit that I use has a cutting width of 6.3mm and a cutting depth of 9.5mm. I find this works great for joinery on 18mm material. The 6.3mm cutting width is a perfect fit for use with 6mm MDF. I cut my own MDF strips for use with this joinery method.\nStep 2: How to Make the MDF Pieces\nTo make the MDF strips I simple cut scrap pieces of MDF to 18mm wide strips. I then sanded them on the belt sander, slightly easing the edges to add a chamfer. This helps the MDF strips slip into the slots easier. Especially when wood glue is added. They can be cut to exact lengths for each joint or cut into smaller pieces and stacked next to each other to fill the slot.\nStep 3: Set Up the Router\nThe beauty of this method is that you don't have to be super precise with set up. I install the slot cutting router bit into the router and set the depth by eye to roughly centre on the sheet material I'm working with. As long as you reference the same side with the base of the router then the pieces will slot together perfectly flush, regardless of how far off centre you are.\nStep 4: Cut the Slots\nCutting the slot in the workpiece is simple, thanks to the bearing guided bit. There is no need for a fence or any other alignment jig. I simply start the groove away from the edge and ease the bit out before reaching the other edge. The slot can be cut in the same way on the mating piece.", "599" ], [ "Easing in and out at either edge so the slot isn't visible from the sides.\nStep 5: Add the MDF Pieces\nThe MDF pieces can then be added to the slot. For this example I didn't use any wood glue but typically, you would add wood glue to the slots and the MDF pieces before assembly. When wood glue is added the MDF swells slightly and makes for an even tighter joint. It's then just a case of slotting the pieces together. Add clamps while the glue dries and you're left with a perfectly flush joint.\nStep 6: 90 Degree Joinery\nThis joinery method even works for 90 degree joints. The first part of the joint is cut exactly the same way as before. The workpiece lay flat and the slot cut along the edge.\nThe mating piece needs the slot cut in the face of the material rather than the edge. This is a little awkward but it's still simple with the right set up. I clamp the workpiece in the jaws of my workbench in an upright position. A vise works great too. Behind the workpiece I add some scrap material. This is to help stabilise the router base as 18mm material is quite thin and the router base can rock slightly. With this secure it's just a case of cutting the slot. Again, easing in and out before reaching each end.\nChip out isn't a huge issue because it's inside the joint and will never be seen but you could use some painters tape to help prevent this from happening. If you're working with MDF you don't have to worry about this at all.\nWith the slots cut it's just a case of adding wood glue and the MDF strips into place. If you need to remove a strip for any reason and you're finding it difficult. Then the claw side of a claw hammer works great to lift it out. Then the pieces can be slotted together forming a 90 degree joint that is perfectly flush on the outside.\nStep 7: Other Methods: Screws & Dowels\nThere are of course lots of different joinery methods you could use with sheet material. Another one that I like is ideal for when it doesn't matter what the joint looks like. I use glue and screws at the corners of drawers, leave the glue to dry and then replace the screws with wooden dowels.", "599" ] ]

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[ [ "Just summing together all the comments and providing some more explicit calculations, we have conservation of four-momentum (which is the amalgamation of the conservation of energy and conservation of momentum), we have:\n$$p^{\\mu}{1}+p{2}^{\\mu}=p_{1}'^{\\mu}+p_{2}'^{\\mu}+p_{\\pi}^{\\mu}$$\nTaking the inner product of each side with itself, we get:\n$$\\left\\langle p_{1}^{\\mu}\\middle|p_{1}^{\\mu}\\right\\rangle+2\\left\\langle p_{1}^{\\mu} \\middle| p_{2}^{\\mu}\\right\\rangle+\\left\\langle p_{2}^{\\mu}\\middle|p_{2}^{\\mu}\\right\\rangle=\\left\\langle p_{1}'^{\\mu} \\middle| p_{1}'^{\\mu}\\right\\rangle + 2\\left\\langle p_{1}'^\\mu \\middle| p_{2}'^{\\mu} \\right\\rangle + 2\\left\\langle p_{1}'^{\\mu} \\middle| p_{\\pi}^{\\mu}\\right\\rangle + \\left\\langle p_{2}'^\\mu \\middle| p_{2}'^{\\mu} \\right\\rangle + 2\\left\\langle p_{2}'^{\\mu} \\middle| p_{\\pi}^{\\mu} \\right\\rangle + \\left\\langle p_{\\pi}^{\\mu} \\middle| p_{\\pi}^{\\mu}\\right\\rangle$$\nWe note that $p^{\\mu}p'{\\mu}=\\left\\langle p^{\\mu} \\middle| p'^{\\mu}\\right\\rangle$ is invaraiant in all frames of reference and that $p^{\\mu}p{\\mu}=m^{2}c^{2}$, we can therefore simplify:\n$$2m_{p}^{2}c^{2}+2\\left\\langle p_{1}^{\\mu} \\middle| p_{2}^\\mu \\right\\rangle = 4m_{p}^{2}c^{2}+4m_{p}m_{\\pi}c^{2}+m_{\\pi}^{2}c^{2}$$\nIf we consider that the second proton is initially at rest we have: $p_{1}^{\\mu}=\\left(\\frac{E}{c},\\vec{p}\\right)$ and therefore:\n$$2m_{p}E=2m_{p}^{2}c^{2}+4m_{p}m_{\\pi}c^{2}+m^{2}_{\\pi}c^{2}$$\nRearranging we get:\n$$E=m_{p}c^{2}+2m_{\\pi}c^{2}+\\frac{m_{\\pi}^{2}c^{2}}{2m_{p}}$$\nUsing the constants $m_{p}=938\\text{ GeV}/c^{2}$ and $m_{\\pi}=139.6\\text{ GeV}/c^{2}$, we get:\n$$E=10.6653 \\text{ TeV} \\implies T = 10.6643 \\text{ TeV}$$\nSo if a proton with 10 TeV of kinetic energy collided with a stationary proton, there is a chance that a pion will be produced.", "66" ], [ "Let me provide some steps of the derivation here to see where the problem had been.\n$$\\mathcal{E} \\Psi_+ = \\frac{\\sigma \\mathbf{P}}{2m} \\left(1- \\frac{\\mathcal{E}}{2mc^2} \\right) \\sigma \\mathbf{P} \\Psi_+$$\nLet's change the notation a little:\n$$\\mathcal{E}=E_c-U$$\n$$E_c \\Psi_+ = \\frac{(\\sigma \\mathbf{P})^2}{2m} \\Psi_+ +U \\Psi_+ -\\frac{E_c}{4m^2 c^2} (\\sigma \\mathbf{P})^2 \\Psi_+ + \\frac{1}{4m^2 c^2} ( \\sigma \\mathbf{P} U \\sigma \\mathbf{P} )\\Psi_+ $$\n$$E_c \\Psi_+ = \\left(1- \\frac{(\\sigma \\mathbf{P})^2}{4m^2 c^2}\\right) \\left( \\frac{(\\sigma \\mathbf{P})^2}{2m} +U + \\frac{1}{4m^2 c^2} ( \\sigma \\mathbf{P} U \\sigma \\mathbf{P} ) \\right)\\Psi_+ $$\n$$E_c \\Psi_+ = \\left( \\frac{(\\sigma \\mathbf{P})^2}{2m} +U - \\frac{(\\sigma \\mathbf{P})^4}{8m^3 c^2}- \\frac{(\\sigma \\mathbf{P})^2 U}{4m^2 c^2} + \\frac{1}{4m^2 c^2} ( \\sigma \\mathbf{P} U \\sigma \\mathbf{P} ) \\right)\\Psi_+ $$\nIt's easy to identify several correct terms from (1) immediately.\nOne important note: <PERSON> et al derive the expression (1) sans the <PERSON> term for the case when no vector potential is present. Which is probably why I initially got all the extra terms.", "818" ], [ "There are two problems with your derivation. The first one is in the calculation of $[\\vec S,\\vec J^2]$. In the final step, you are implicitly using $\\vec S\\times \\vec S$ which is false.", "359" ], [ "A close attention to the anticommutation rules gives: $$ \\vec S\\times\\vec S = i\\hbar\\vec S $$ so this leads to: $$ [\\vec J{}^2,\\vec S] = 2i\\hbar((\\vec S\\times \\vec J)-i\\hbar \\vec S) $$\nYou also have a second problem in the triple cross product formula. If you look closely, you are implicitly assuming that the three operators commute when you apply it.\nInstead, you'd get: $$ ((\\vec S\\times \\vec J)\\times \\vec J)k = S_lJ_kJ_l-S_kJ_lJ_l\\ = S_lJ_lJ_k+S_l i\\hbar\\epsilon{klm}J_m-S_kJ_lJ_l $$ so in vectorial notation: $$ (\\vec S\\times \\vec J)\\times \\vec J = (\\vec S\\cdot \\vec J)\\vec J+i\\hbar(\\vec S\\times \\vec J)-\\vec S\\vec J{}^2 $$ as you can see, you forgot the extra cross product term and the ordering of your second term was a bit cavalier. You can further symmetrize the third, final term: $$ \\vec S\\vec J{}^2 = \\frac{1}{2}(\\vec S\\vec J{}^2+\\vec J{}^2\\vec S-[\\vec J{}^2,\\vec S])\\ =\\frac{1}{2}(\\vec S\\vec J{}^2+\\vec J{}^2\\vec S)-\\frac{1}{2} [\\vec J{}^2,\\vec S] $$ to get: $$ (\\vec S\\times \\vec J)\\times \\vec J = (\\vec S\\cdot \\vec J)\\vec J+i\\hbar(\\vec S\\times \\vec J)-\\frac{1}{2}(\\vec S\\vec J{}^2+\\vec J{}^2\\vec S)+\\frac{1}{2} [\\vec J{}^2,\\vec S] $$\nIncorporating these modifications, you'd rather get: $$ [\\vec J{}^2,[\\vec J{}^2,\\vec S]] = 2i\\hbar[\\vec J{}^2,(\\vec S\\times \\vec J)-i\\hbar \\vec S)]\\ = 2i\\hbar([\\vec J{}^2,\\vec S]\\times \\vec J+\\vec S\\times[\\vec J{}^2,\\vec J]-i\\hbar[\\vec J{}^2,\\vec S])\\ = -4\\hbar^2(((\\vec S\\times \\vec J)-i\\hbar \\vec S)\\times \\vec J-\\frac{1}{2}[\\vec J{}^2,\\vec S])\\ = -4\\hbar^2((\\vec S\\cdot \\vec J)\\vec J+i\\hbar(\\vec S\\times \\vec J)-\\frac{1}{2}(\\vec S\\vec J{}^2+\\vec J{}^2\\vec S)+\\frac{1}{2} [\\vec J{}^2,\\vec S]-i\\hbar(\\vec S\\times \\vec J)-\\frac{1}{2}[\\vec J{}^2,\\vec S])\\ = -4\\hbar^2((\\vec S\\cdot \\vec J)\\vec J-\\frac{1}{2}(\\vec S\\vec J{}^2+\\vec J{}^2\\vec S)) $$ which is the advertised form, with $\\alpha = -4\\hbar^2$ (which has the correct dimensions).\nHope this helps and tell me if something's not clear.", "532" ], [ "Calculating vertex factor for scalar field theory\nI am practising basic QFT and am having some trouble with calculating the vertex factor of an interacting theory involving two real scalar fields, $\\phi_{1}$ and $\\phi_{2}$.\nIf I create a generic Lagrangian with interaction terms:\n$$\\mathcal{H}{\\text{int}}=g\\phi{1}^{2}\\phi_{2} + q\\phi_{1}^{2}\\phi_{2}^{2}$$\nI want to calculate the vertex factors associated with these interactions. So to calculate the $\\phi_{1}^{2}\\phi_{2}$ vertex, I calculate the three-point Green's function:\n$$G^{(3)}(x,y,z)=\\langle\\Omega|T\\phi_{1}(x)\\phi_{1}(y)\\phi_{2}(z)|\\Omega\\rangle = \\frac{\\langle0|T\\phi_{1}(x)\\phi_{1}(y)\\phi_{2}(z)\\exp\\left(-i\\int_{-\\infty}^{\\infty}\\mathcal{H}{\\text{int}}\\:\\mathrm{d}^{4}s\\right)|0\\rangle}{\\langle0|T\\exp\\left(-i\\int{-\\infty}^{\\infty}\\mathcal{H}_{\\text{int}}\\:\\mathrm{d}^{4}s\\right)|0\\rangle}$$\nWe can expand the exponential involving $\\mathcal{H}_{\\text{int}}$ to first order in $g$ and $q$:\n$$\\exp\\left(-i\\int_{-\\infty}^{\\infty}\\mathcal{H}{\\text{int}}\\:\\mathrm{d}^{4}s\\right)=1-ig\\int{-\\infty}^{\\infty}\\phi_{1}^{2}(s)\\phi_{2}(s)\\:\\mathrm{d}^{4}s-iq\\int_{-\\infty}^{\\infty}\\phi_{1}^{2}(s)\\phi^{2}_{2}(s)\\:\\mathrm{d}^{4}s$$\nClearly by <PERSON>'s theorem, any term without an even number of $\\phi_{1}$ or $\\phi_{2}$ terms will disappear, so the denominator will become:\n$$\\langle0|T\\exp\\left(-i\\int_{-\\infty}^{\\infty}\\mathcal{H}{\\text{int}}\\:\\mathrm{d}^{4}s\\right)|0\\rangle = 1-iq\\int{-\\infty}^{\\infty}\\langle0|\\phi_{1}^{2}(s)\\phi_{2}^{2}(s)|0\\rangle\\:\\mathrm{d}^{4}s = 1 - iq\\int_{-\\infty}^{\\infty}\\:\\mathrm{d}^{4}s\\Delta_{F}^{(1)}(0)\\Delta_{F}^{(2)}(0)$$\nWhere $\\Delta_{F}^{(1)}(z)$ is the Feynman propagator for $\\phi_{i}$.\nMy understanding is (from this other question I asked), that terms containing a tadpole diverenge ($\\Delta^{(i)}{F}(0)$) can be set to zero using the requirement that $\\langle \\phi{i}\\rangle = 0$, so the denominator evaluates to $1$.", "281" ], [ "<PERSON> is equating the different length scales associated.\nIn quantum mechanics, the characteristic length scale is decided by the mass of the particle. It is known as Compton wavelength ($\\lambda_c$), and roughly speaking, it sets the length scale where relativistic quantum field theory becomes important for the description of physics; because if you try to localize a particle such that the uncertainty in position is smaller than $\\lambda_c$, the the uncertainty in momentum becomes high enough to (from $E^2 = m^2 c^4 + p^2 c^2$) induce uncertainty in energy of the order of the mass of the particle. This means that at such small length scales, and equivalently, high energy/momentum scales, we must take special relativity and particle production/annihilation into account.", "976" ], [ "The Compton wavelength is given by:\n$$\\lambda_c = \\frac{\\hbar}{mc}$$\nIn general relativity, the characteristic length scale is also decided by mass, but is directly proportional to it. It is known as Schwarzschild radius $r_S$. The event horizon of a static and spherically symmetric object lies at $r=r_s$ and is given by:\n$$r_s = \\frac{2 G m}{c^2}$$\nSubstituting $r_s$ for $\\lambda_c$ and barring a factor of $\\sqrt{2}$, we can write the characteristic mass scale for such a situation in terms of the three fundamental constants of the three fundamental theories: $c$ of special relativity, $G$ of general relativity and $\\hbar$ of quantum mechanics, and it is known as Planck mass:\n$$m_p = \\sqrt{\\frac{\\hbar c}{G}}$$\nSo the Schwarzschild radius of a black hole of mass equal to the Planck mass is its Compton wavelength.\nThe number of microscopic states of a black hole with given macroscopic characteristics (like charge, mass and angular momentum) can be written in terms of the area $A$ of the event horizon. This is known as black hole entropy and is given by:\n$$S = \\frac{kAc^3}{4G\\hbar}$$\nwhere $k$ is the <PERSON>'s constant.\nThe issue that black holes are not entirely 'black' and end up radiating because of particle production when quantum mechanics is involved has led to many debates and open questions that fall under the umbrella term of black hole information paradox.", "688" ], [ "<PERSON> symbols of semilog metric\nProblem 17.3a in <PERSON>'s \"A general relativity workbook\" requires to determine the only non-zero <PERSON> symbol for the 2D semilog pq coordinate system defined as $p=x$ and $q=e^{by}$. What puzzles me is that I found more than one non-zero <PERSON> symbol, and I wanted to ask you what am I doing wrong.\nFirst of all, I calculated the metric $g_{\\mu\\nu}'$ of the coordinate system as $$ g_{\\mu\\nu}' =\\frac{\\partial x^\\alpha}{\\partial {x^\\mu}'}\\frac{\\partial x^\\beta}{\\partial {x^\\nu}'}g_{\\alpha\\beta} =\\frac{\\partial x}{\\partial {x^\\mu}'}\\frac{\\partial x}{\\partial {x^\\nu}'} + \\frac{\\partial y}{\\partial {x^\\mu}'}\\frac{\\partial y}{\\partial {x^\\nu}'} $$ given that $g_{\\alpha\\beta}$ for the 2D Euclidean plane is the identity matrix. Calculating this, I got $$ g_{\\mu\\nu}'= \\begin{bmatrix} 1 & 0\\ 0 & \\frac{1}{p^2 b^2} \\end{bmatrix} $$ Is this correct?\nOnce this is done, I calculated the <PERSON> symbols by comparing the geodesic equation expressed in terms of the metric elements $0=\\frac{d}{d\\tau}\\left(g_{\\mu\\nu}\\frac{dx^\\nu}{d\\tau}\\right)-\\frac{1}{2}\\partial_\\mu g_{\\alpha\\beta}\\frac{dx^\\alpha}{d\\tau}\\frac{dx^\\beta}{d\\tau}$ with the same equation expressed via the Christoffel symbols $0=\\frac{d^2x^\\mu}{d\\tau^2}+\\Gamma^\\mu_{\\alpha\\beta}\\frac{dx^\\alpha}{d\\tau}\\frac{dx^\\beta}{d\\tau}$.", "818" ], [ "If we set $\\mu=p$ in the first equation we get $$ 0=\\frac{d}{d\\tau}\\left(g_{p\\nu}\\frac{dx^\\nu}{d\\tau}\\right)-\\frac{1}{2}\\frac{\\partial g_{\\alpha\\beta}}{\\partial p}\\frac{dx^\\alpha}{d\\tau}\\frac{dx^\\beta}{d\\tau}=\\ =\\frac{d^2p}{d\\tau^2} - \\frac{1}{2}\\frac{\\partial g_{qq}}{\\partial p}\\left(\\frac{dq}{d\\tau}\\right)^2=\\ =\\frac{d^2p}{d\\tau^2} + \\frac{1}{b^2p^3}\\left(\\frac{dq}{d\\tau}\\right)^2 $$ Setting $\\mu=p$ in the <PERSON> version of the geodesic equation, we then can conclude that $\\Gamma^p_{pp}=\\Gamma^p_{pq}=\\Gamma^p_{qp}=0$, while $\\Gamma^p_{qq}=\\frac{1}{b^2p^3}$. By doing the same procedure with $\\mu=q$, I got that $\\Gamma^q_{pp}=\\Gamma^q_{qq}=0$ and that $\\Gamma^q_{pq}=\\Gamma^q_{qp}=-\\frac{1}{p}$.\nThis means that three <PERSON> symbols are non-zero, in opposition with the text of the exercise. Am I missing something, or is the text wrong?", "394" ], [ "I would agree with <PERSON>'s suggestion that the most \"fundamental\" definition of momentum is the quantity that is conserved when the Lagrangian is invariant under spatial translations $\\boldsymbol{x}\\rightarrow\\boldsymbol{x}+\\boldsymbol{s}$.\nHowever, do terms like Lagrangian even make sense when we try to include massless objects?\nYes, absolutely. In fact the machinery used to describe such particles, quantum field theory, is expressed in terms of Lagrangians.\nLagrangian mechanics and generalized momentum\nLet's start with the simpler classical dynamics notion of momentum. We start with a Lagrangian, expressed in terms of the generalized coordinates $q_i$ and their time derivatives, $$L(q_i, \\dot{q}_i)=T(\\dot{q}_i)-V(q_i)$$ where $T$ and $V$ are the kinetic and the potential energies, respectively. The reason we care about the Lagrangian is that it allows us to easily derive the equations of motion for the system under consideration using the Euler-Lagrange equations, $$\\frac{\\partial L}{\\partial q_i}-\\frac{d}{dt}\\left(\\frac{\\partial L}{\\partial\\dot{q}_i}\\right)=0$$ which are a direct result of the principle of least action. There is a famous and beautiful theorem in mechanics by <PERSON>, which states that for every continuous symmetry of the Lagrangian there exists some quantity that stays the same throughout time. More precisely, for some continuous transformation parameterised by $s$, $q_i(t)\\rightarrow Q_i(s,t)$, if $$\\frac{\\partial}{\\partial s}L(Q_i(s,t),\\dot{Q}_i(s,t),t)=0$$ then the quantity $$\\sum_i\\frac{\\partial L}{\\partial\\dot{q}_i}\\frac{\\partial Q_i}{\\partial s}$$ is conserved though all time.", "101" ], [ "These $\\partial L/\\partial\\dot{q}_i$ are known as generalized momenta.\nDefining momentum\nConsider the specific case of a collection of free particles, which has a Lagrangian $$L=\\frac{1}{2}\\sum_i m_i\\dot{\\boldsymbol{x}}_i^2-V(|\\boldsymbol{x}_i-\\boldsymbol{x}_j|)$$ Now consider making a translation $\\boldsymbol{x}_i\\rightarrow\\boldsymbol{x}_i+s\\mathbf{n}$ where $\\mathbf{n}$ is an arbitrary vector. The above Lagrangian is clearly invariant under such a transformation. Therefore we know per <PERSON>'s theorem that the quantity $$\\sum_i\\frac{\\partial L}{\\partial\\dot{\\boldsymbol{x}}_i}\\frac{\\partial(s\\mathbf{n})}{\\partial s}=\\sum_i m_i\\dot{\\boldsymbol{x}}_i\\cdot\\mathbf{n}$$ is conserved. But this is just our usual conservation of the total momentum $\\sum\\boldsymbol{p}_i=\\sum m_i\\dot{\\boldsymbol{x}}_i$ along the direction of $\\mathbf{n}$! So we see that the quantity momentum naturally arises as the thing that is conserved under space-translation symmetry.\nBut this notion of momentum extends much further than free particles. It can be applied to any Lagrangian with space-translation symmetry, with the conserved quantities that arise being given the label momentum.\nSo now, how do massless particles like photons fit into this? For describing particles such as photons we use quantum field theory, however it suffices here to stick to the classical theory.\nLagrangian of fields\nLike the name suggests, in field theory our dynamical variables are fields which are themselves functions of space and time (or, spacetime). As such we replace the usual Lagrangian with a Lagrangian density, $\\mathcal{L}$ which is defined by $$L=\\int\\mathrm{d}^3\\boldsymbol{x}\\,\\mathcal{L}(\\phi(x),\\partial_\\mu\\phi(x),t)$$ where $\\phi(x)$ is the field as a function of spacetime coordinate $x=(t,\\boldsymbol{x})$ and $\\partial_\\mu=\\partial/\\partial x^\\mu=(\\partial/\\partial t,\\nabla)$ is the four-gradient.", "101" ], [ "The above answers seem to nicely summarize why charge is conserved in every frame of reference. I would like to take a different approach as to why that makes sense, and why the charge conservation law holds.\n1. Charge, current and conservation:\nThe most simplest way to state the conservation of charge is to say, $$\\frac{dQ}{dt} = 0$$\nThat the rate of change of charge in time is $0$, implying that the quantity of charge is a constant.\nBut, sometimes charge can decrease in a system. This does not violate the supreme principle, but rather states that charge can 'leak' or flow through an area, causing the charge in the system to decrease, and the charge outside to increase. So, the amount of charge in the entire universe is the same, but for smaller systems the above equation may not hold true.\nConsider a box with some charge inside of it. The charge can flow out through any of the faces of the box, thus decreasing the overall charge inside (it can also increase if the charges are instead entering the box). So, you need to take into account this flow of charges, called a current to make sure that the conservation law holds. The resulting mathematical form is:\n$$\\frac{d\\rho}{dt} + \\nabla . J^i = 0$$\nwhere the $\\rho$ represents the density of charge inside the box, and $J^i$ is the current vector, because current can flow through the $x$, $y$, and $z$ axes; so we use a vector to keep track of them all. What the above expression says is: the rate of change of charge in the box and the rate of change of current flowing in or out of it, is going to be conserved.\n2. Four vectors, dot products and Lorentz invariance:\nIn Relativity, we use something known as four-vectors, which are 4 dimensional vectors. Usual vectors have only three components: one corresponding to each dimension of space; in Relativity, we consider a fourth dimension: time.", "780" ], [ "So, vectors in Relativity have four components, one corresponding to time, and three to space. We denote these vectors by $$A^{\\mu}, \\mu = (0, 1, 2, 3)$$ where the $0$ index corresponds to the time component and the other three to the space components.\nNow, let's move on to Lorentz invariance. In Special relativity, whenever we want to consider events from a different reference frame, we use something known as Lorentz transformations. I am going to leave a few nice resources in the further reading below, but for now, that is enough information.\nIf a certain quantity does not change when the Lorentz transformation is applies to it, we say it is Lorentz invariant.\nSo, some of the things that are always Lorentz invariant are the dot product between two four-vectors. Again, for length purposes, I will leave a link to some resources below, but simply put, dot products between two vectors can be denoted as: $$Product_{dot} = A^\\mu B_\\mu$$\nThe only constraint is that the index of the four vectors should be the same and they should be repeated upstairs and downstairs. Expanding this expression, we get: $$A^{\\mu}B_{\\mu} = -(A^0 B_0) + (A^1 B_1) + (A^2 B_2) + (A^3 B_3)$$ which is a scalar and is Lorentz invariant. These scalars are called Lorentz scalars.\n3. Bringing it all together:\nIn Special Relativity, we denote the charge and current of a particle as a four vector $J^{\\mu}$. The time component is $\\rho$ and the space components are $J^i$. There is another four vector $\\partial_{\\mu}$ which is defined to be: $$\\partial_{\\mu} = \\left (\\frac{\\partial}{\\partial t}, \\frac{\\partial}{\\partial x}, \\frac{\\partial}{\\partial y}, \\frac{\\partial}{\\partial z}\\right)$$\nOkay. Now, particles have some properties, like mass and charge that do not change when you shift frames. Similarly for the conservation of charge, you can write it as $$\\partial_{\\mu}J^{\\mu} = 0$$ which is a dot product, so it is naturally a <PERSON> invariant.\n4. So, can charge vary for observers?\nI took an unconventional way of answering here, by first showing the true way of expressing the conservation of charge and then going through a long way to show why the law hold even when our frames change.", "418" ] ]

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[ [ "Free-Formed Solar Chirping Bird Pendant Using 0603 SMD Components (BEAM Electronics)\nIntroduction: Free-Formed Solar Chirping Bird Pendant Using 0603 SMD Components (BEAM Electronics)\nI had one weekend between finishing quite a stressful university term and starting to study for my exams so I thought, \"You know what would be really relaxing, finally trying to make a free-frormed circuit using 0603 components.\". No way that could be stressful right? 😂😂\nThe final circuit chirps on and off for about 20-40 seconds (watch the video to hear it chirping) and then stays off for another 1-2 minutes before chirping again.\nI originally just wanted to make this as small as possibly but in doing so I realised it could actually be made as a pendant and I am very glad I turned it into a pendant in the end as I think the frame adds so much to the circuits aesthetic and protects the circuit from getting damaged. I don't intent to wear this often (in fact I hardly expect to let it see the sun at all because, as I know from previous chirping circuits, the noise gets old quick) but I reckon this would be the absolute perfect thing to wear to a maker faire or similar event!\nIn the final photos in the introduction you can see my first attempt to miniaturize this circuit by designing a PCB back in 2019 (this was one of my first PCB projects and it doesn't even work, the solar panel is too small!). As well there is a comparison in size between the breadboarded version, PCB, and free-formed SMD version\nEdit: wobbler has kindly amplified the chirping audio as it was a little quiet in the original video. If you are struggling to hear the chirping in the video try the audio file attached below. It is still very true to how the circuit sounds in real life just louder and clearer =).\nSupplies\nEDIT: I don't know what happened here but my supplies section seems to have disappeared at some point so I will summarise the important components again.\nResistors: All 0603.\nCapacitors: 0603 for the 1nFs and the rest had to be 0805 as they are much easier to source. I also used a couple of axial 10nF caps.\nDiodes: 1N4148WS.\nPhotodiode: I used a VEM6010X01CT-ND though any choice will probably do and you may be able to find smaller with a more suitable pinout.\nSolar panel: KXOB25-02X8F-TB which is a very small and efficient 5.5v panel. Quickly becoming a favourite for me!\nSuper capacitor: 100mF, 5.5v square super capacitor from KEMET.\nPiezo element: 9x9mm externally driven piezo speaker.\nInverter IC: 74HC14 SOIC (hex Schmitt inverters)\nBrass: 0.02\" (0.51mm) for most of the circuit.", "1003" ], [ "3/64\" (1.19mm) for the frame 1/32\" (0.81mm) for the loops.\nTools: Most important for this project is a clean soldering iron tip, flux, and good solder. I used multicore 60/40 solder at 0.7mm which was fine but at times I did want thinner solder. Also important for soldering are fine tweezers, Blu Tack, and perhaps some form of magnification (I was lucky I did not need magnification for this project as I am not used to working through a microscope or anything so it gives me headaches). You will also need various jewellers pliers (I bought a set from my local electronics hobby store that work great) and sids cutter for forming the brass.\nStep 1: Schematic\nThis is yet another circuit that was originally designed by <PERSON> way back in 199 (found on the solarbotics.net site). I have modified it a little, mostly to change the frequency of chirps, and a few other modifications to make it sound less robotic.\nThe circuit is essentially just 4 oscillators. From left to right, the first and second oscillators turn on and off slowly to turn the other oscillators on and off. In Wilf's original circuit this creates some kind of randomness in the number of chirps but the circuit is constantly chirping. With the components I chose, the circuit turns off for a very long time (1-2 minutes) and is on for a shorter time (20-40 seconds) based on the second oscillator values (10uF, 10M, 5M). The first oscillator values (1uF, 10M, 3.", "552" ], [ "BEAM Solar Powered Pummer (Heart Shaped PCB)\nIntroduction: BEAM Solar Powered Pummer (Heart Shaped PCB)\nThis is a project that I have been meaning to finish for over a year now. it is a heart shaped, BEAM based pummer circuit I made to charge up during the day and flash like a heart beating at night. The solar engine is a SIMD1 solar engine by <PERSON> and the pummer is a modified version of his power saver flasher which flashes 2 LEDs off the one oscillator.\nSee:\nhttp://solarbotics.net/library/circuits/bot_pummer...\nhttp://solarbotics.net/library/circuits/se_noct_SI...\nMy final design lasts about 3 hours from when the sun starts to go down.\nI personally love creating PCBs as a step up from breadboard or perfboard circuits, and I especially like designing PCBs that go a little beyond just connecting components. Hopefully through this Instructable you will see that while a PCB designer such as Eagle can be superbly powerful, creating a functional and aesthetic circuit such as the one presented here can be quick, fun and really accessible. I spent a day designing it all and only spent around $30USD on the PCB and components! Granted I already had assorted resistors, caps, and a soldering iron.\nStep 1: EDIT: What Is a Pummer?\nIt seems in the comments that there is a little confusion as to what a pummer is, which is very fair.\nBEAM robotics is a \"style\" of analogue circuit building, popular in the late 90s and early 2000s. BEAM circuits use minimal, analogue components, often to complete simple and very organic tasks. In BEAM robotics, a pummer is a type of circuit that displays a pattern of lights or sounds.\nSee the Wikipedia pages for a broader overview here:\nhttps://en.wikipedia.org/wiki/BEAM_robotics\nhttps://en.wikipedia.org/wiki/Sitter_(BEAM)\nStep 2: Prototyping\nThe first step is to prototype the circuit on a breadboard.", "982" ], [ "I used a design almost exactly the same as Wilf's pummer from the link in step 1 however I replaced a 100k resistor at the output of the pummer with an LED and added a resistor between the output capacitor and the output LEDs to get a less bright, but longer flash. You can see here in the second photo the waveform at the node between the output LED and resistor in Wilf's original design. The peak above 2.2v is where the LED lights and the dip below just dumps charge through the 100k resistor. In my revision seen in photos 3 and 4, both the peak above 2.2v as well as the lower peak create a flash (because the voltage is being regulated to ~2.9v by the blue LED, in photo 4 you can see the other 2.2v difference, this time between the 2.9v rail and the node between the output LEDs). This revision does mean that the reference voltage LED does have to be a higher voltage than your output LEDs (and hence the circuit will run for less time) however there is less wasted charge. I like this way better however 2 oscillators, with the second acting as a slave to the first and using something closer to <PERSON>'s original circuit would also work. Just let me know if I can clarify any of this and excuse the photos of the oscilloscope screen, I had some trouble saving to USB.\nAs I was almost following <PERSON> design exactly, I mostly used this step to calculate what value components I was looking at using to make the flashes beat at a heart-like rate.\nOnce I had the circuit operating as expected I used this circuit to calculate roughly how long my pummer would last once it started flashing at night.\nTo calculate how long our circuit will last we can use 2 formulas based on the charge stored in, and the charge leaving the storage capacitor.\nFirst we know that Q=CV that is, the charge in the capacitor, \"Q\", is equal to the capacitance x the voltage across the capacitor.\nWe also know the formula for current I=Q/t where \"I\" is the current, \"Q\" is charge and \"t\" is time.\nRearranging these we can get I=(C*ΔV)/Δt where \"ΔV\" represents the change in voltage and \"Δt\" change in time (in seconds)\nHence, by measuring the voltage at one point in time and then measuring it again a certain amount of time later (I usually go about half an hour for more accurate results) we know have all the numbers on the right half of the equation and we can see how much current the circuit is drawing from the capacitor on average.", "552" ], [ "Light-Tracking BEAM Robot Head\nIntroduction: Light-Tracking BEAM Robot Head\nHey all! Super excited to finally be sharing this robot with the internet. It is a light-seeking robot that is entirely free-formed using BEAM style analog logic, that means no microcontrollers, and it runs entirely on solar power. It is a bit long but definitely watch my 30 minute explanation video if you want more detailed information on how everything works.\nWhen I was very very young and just starting to get interested in electronics, these analog BEAM circuits were already going the way of the dinosaurs to make way for these newfangled PICAXE controllers or even an Arduino if you were lucky enough! As such, I only ever saw the tail end of the BEAM movement but something about those circuits still tickles me to this day. There is something about manipulating the movement of electrons at the most base level, no abstracting it with 1s and 0s, in order to make a pile of silicone... intelligent!\nThis circuit is much more finicky, took a tonne more work, and is nowhere near as powerful/versatile as a microcontroller based robot that would do the same thing, but I hope you will agree that there is something special about him. Maybe I am getting too philosophical here but there is something about his analogue nature that makes him more lifelike, gives him more personality than even a complicated digital program. Indeed, he was out of commission for just over a week while I waited for time to fix his motors and I really did miss him sitting there on my desk.In the demonstration videos you will even see a couple of animals/insects who I caught curiously inspecting the robot, I don't think they could tell if it was alive or not either ;).\nIn any case, I think that all of this philosophy is secondary to the main function of this robot which is... to look nice. I definitely think of this robot as an electronic sculpture and the \"life\" that the circuitry brings all just adds to the art.\nAll of my Instructables fall under 2 camps.\n1.", "51" ], [ "Follow along with the instructions as I have shown.\n2. Mostly just inspiration and not something to follow exactly.\nThis Instructable falls cleanly in the second category and you would definitely need to understand the whole schematic and do lots of prototyping and testing if you were to attempt this project or something similar.\nI will try not write as much as I tend to do as this is already a very large project so if I miss anything just ask in a comment.\nFinally, some of this is out of order as I was jumping ahead and making sections while waiting for other parts. So I have presented it in the most logical order build wise but there may be some continuity errors.\nEDIT: For anyone curious, my marble machine and tiny photopopper are both still going strong!\nSupplies\nTools\nMy 2 favourite hand tools are files and a jewellers saw. My 2 favourite power tools are my belt grinder and drill press. Alongside sandpaper and blowtorches for soldering these are the only tools I used to make the whole mechanical assembly.\nFor the free-forming I used a chisel tip soldering iron (only bringing out the fine tip for corrections I had to make to already densely populated sections of the free-forming). I also used a set of needle nose pliers from my local electronics hobby store and a pair of side cutters for all of the wire shaping.\nComponents\nI cant list all of the components here so I will just list the important ones:\nSolar panel: SM531K12L from digikey, 1.37W at 8.29V. It is quite pricey for a single panel but definitely the most efficient indoor solar panel I have come across at this size.\nMotors: 15RPM 3V N20 motor (45RPM works also and were the motors I originally chose but they were too fast. I bought a lot of N20 motors to test and it would seem that the 45RPM and 15RPM use the same speed motor with different gearing, while the 30RPM motors use a weaker motor with the 45RPM motor gearing. So while 30RPM would probably be the better choice, the 30RPM motors I bought did not work with the circuit I designed.\nICs: 74HC240s for the octo inverters and a 74HC14 for the hex inverter for the audio processing.\nCapacitors: There are many caps in this build but I wanted to mention that I generally chose long life electrolytics and high(ish) quality ceramics for a longer lifespan.", "98" ], [ "Joule Thief Torch With Casing\nIntroduction: Joule Thief Torch With Casing\nIn this project you will learn about how to build a Joule Thief circuit and the appropriate casing for the circuit. This is a relatively easy circuit for beginners and intermediates.\nA Joule thief follows a very simple concept, which is also similar to its name. It extracts or \"steals\" joules (energy) out of low-voltage systems. E.g. Most non-functional batteries actually have about 20%-30% of juice still in them. However their voltage is too low, and it is not able to power anything. The Joule thief circuit can actually harvest this low-voltage energy from batteries (or any source) and power a standard 5mm LED light quite brightly. The output is not limited to a LED.\nThis is a very easy, practical, and useful circuit to have in your house. If you can't find a working battery that you need urgently, or you want to make complete use of the batteries you buy, this would be perfect for you.\nFinally, this Instructables will also showcase a 3D printed casing for the Joule thief. However, if you do not have a 3D printer then you can check out my Laser cut acrylic box or design a casing yourself. Even just a plastic box would be satisfactory. I would not recommend leaving the circuit without a casing.\nStep 1: Supplies and Tools\nSupplies:\n1. Perf board\n2. AA battery holder (can be for 2 batteries or 1)\n3. Ferrite toroid (with two coils over it)\n4. Tactile latch switch\n5. 5mm LED (any colour)\n6. 5mm LED bezel + nut\n7. NPN transistor (I used C1815)\n8. 3mm Nuts x4\n9. 3mm Bolts x2\n10. Wires\nTools:\n1. Soldering wire and iron\n2. Wire-cutter pliers\n3. Multimeter (if you don't have one you can make one DIY. Check out my Arduino powered multimeter)\n4. Desoldering pump (optional)\n5.", "98" ], [ "Needle-nose pliers\n6. Pencil/pen/marker\n7. Superglue\nStep 2: Circuit Schematic and How It Works\nHere is a very that very nicely explains how a joule thief works:\nCREDIT TO ELECTRONICGURU FOR IMAGES\nStep 3: Securing Battery Holder to Board\n1. Using a black marker, I marked where the holes in the battery holder were on the PCB.\n2. I used the wire cutter pliers to make the holes in the perf board. Soon enough it was big enough for the 3mm bolt. If you have a handheld or electric drill this process is a lot easier. It is important to test if the holes are big enough for your bolt.\n3. I added an extra set of nuts between the perf board and battery holder to stop the bolt from protruding out of the other end so much.\n4. The two remaining screws were used to secure battery holder onto the perf board.\nStep 4: Understanding C1815 Transistor\nSome transistors have different schematics and pinouts. Therefore, just as clarification, I wanted to state which pins of the transistor are base/collector/emitter\nMoving from left to right with the flat side facing you, the pins are base, collector, and emitter in that order. This is exactly as what is shown in the diagram.\nStep 5: Preparing Ferrite Toroid\nI got the ferrite toroid from a broken RC car circuit\n1. Taking thin enamelled copper wire I wound the coil around the ring-shaped ferritetoroid 7 times. See picture\n2. The wire was cut after 7 coils with length to spare for soldering and connections. The second coil started in the same place where the first coil was started. Following the shape of the first coil, the second coil also was pulled out after 7 winds and cut with excess.\n3. To differentiate between the coils coil 1 had much longer legs than coil 2.\n4. Since my ferrite toroid was very small, I used a very thin copper coil wire. Most likely 26 SWG. If your toroid is bigger then you can use bigger and even normal wires\n5. After this, you would have 4 different wire ends. 2 for coil 1 and 2 for coil 2. These 4 can also be written as 2 for the starting side and 2 for the end side.\n6. To simplify remembering the coils, I gave the following names to the coil ends. S1, S2, E1, E2. The S and E stand for start side and end side. 1 and 2 stand for the coil number.\n7.", "611" ], [ "Solar BEAM Marble Machine\nIntroduction: Solar BEAM Marble Machine\nLadies and gentlemen, I present to you, my marvellous \"Solar BEAM Marble Machine\"! A brass marble machine with a solar powered, solenoid actuated, lever lifting mechanism!\nThis machine uses capacitors to store energy from the sun and, once charged, dumps all that energy into a coil, pushing away a magnet, and lifting a small steel ball through the use of a lever.\nIn previous BEAM related Instructables there was some confusion surrounding my use of the term BEAM. I don't think it is such a common concept anymore. How I understand it is that BEAM is a hobby electronics movement from the late 90s to early 00s that focused on turning found or common components into analogue circuits and robots. https://en.wikipedia.org/wiki/BEAM_robotics\nThe circuit used here is a type of very common BEAM circuit called a solar engine which stores charge from a solar cell (or other low current power source) in a capacitor until there is enough usable energy (i.e. the capacitor voltage is high enough) to do some meaningful work. This is normally used to run a small motor in short bursts even when the sun is not strong enough to power the motor directly. It is especially helpful in this particular machine as there is no way a solar panel of this size would be able to provide the current necessary to drive the coil while capacitors have no trouble. Furthermore, even if we had the necessary power, we would not want current running through the coil at all times.\nFor this project, the word BEAM works on two levels, one being for the electronics style, and the second being that the main lifting mechanism is a lever or... a beam =D\nNote: In the past I have tried taking all photos on a white background but I found, with the work I do, it often gets dirty too quick. I have tried a black background here, let me know what you think.\nStep 1: The Lever\nOne of the most important parts of this design is the lever as the coil and magnet creates a rather strong force but only when the magnet is close. Hence, we can use a first order lever to translate a strong force over a short distance into a smaller force but over a much larger distance\nStep 2: The Solar Engine\nThe other important part of this design is the solar engine which, as mentioned in the introduction, stores energy from the solar panel in some large capacitors until there is enough to do some useful work.", "780" ], [ "I used a SunEater I solar engine which you can read more about here http://faq.solarbotics.net/suneater/suneater.html with some slight tweaks to work with my coil. In the past I have only used a simple FLED based solar engine however they are always finicky to get working correctly and especially with a coil dumping so much power. So I opted for the slightly more complicated, but much more robust SunEater!\nYou will see on the left of my schematic we have 2x 4700uF caps in parallel, these form the bulk of our energy storage. I used low ESR, 16V capacitors. The low ESR lets the capacitors discharge quicker and I would have preferred 25V as if something does fail and the solar panel is in full sun it can get quite close to 16V and potentially damage the capacitors however I could not find 25V low ESR capacitors this large at my local electronics store. You will also notice a 100uF capacitor which I use to help provide the initial burst of energy as its ESR will be much lower than that of the 4700uF. I'm not sure if this capacitor even helps in this particular build however it has helped with similar circuits in the past so I keep including it. I also have a small, 10nF capacitor across the power supply as without it, sometimes the circuit would lock up and oscillate.\nI also swapped out the green LED which is used as a voltage reference for when the circuit should trigger and replaced it with an 8.1V zener diode. This means the circuit doesn't trigger until the capacitors get to around 8.3V which I found is the right amount for my circuit. If you were to build something similar you may have to experiment to get the right value. In fact, in my final design, I left this diode replaceable for future adjustment.\nI also expected high current to flow through the final PNP/coil path and although in testing the final design, it seems I could have in fact gone with a smaller transistor, I opted to use the TIP32 power transistor as it should be able to better handle large currents.\nWe also need a flyback diode across the coil to drain any excess power created by the coil's magnetic field collapsing on itself which could potentially damage components.", "552" ], [ "Tiny, Solar Powered, Light Seeking BEAM Bot (Mini Photopopper)\nIntroduction: Tiny, Solar Powered, Light Seeking BEAM Bot (Mini Photopopper)\nToday I will show you how I made this tiny little robot!\nSince I first mentioned the word in an Instructable and got a couple questions about it, every new BEAM Instructable I feel the need to explain my understanding of the term \"BEAM robotics\". Wikipedia will tell you that BEAM stands for Biology Electronics Aesthetics and Mechanics, and though I have heard conflicting theories about the name in the past I do feel that BEAM embodies these aspects. It is a style of electronics developed in the late 90s and early 2000s using mostly found components in ways that are quite elegant or clever, in order to create the most basic intelligent robots.\nThis particular style of robot know as a photovore, phototrope or photopopper, meaning it uses some very simple logic to locomote toward light.\nMaking tiny photopoppers has been done before, indeed even I have tried (in the video you can see my attempt from 2018 built on a PCB I designed), but I am really happy with how this particular one turned out and am excited to share the process with you all!. I have included links to other examples below, but I wanted to make this new bot for a couple reasons.\n1. I knew I could do better than my predecessors just because these (relatively) new IXOLAR monocrystaline solar panels from digikey seemed to have incredible specs and oh boy did they work awesome in the end! Solar panel efficiency is tied to surface area so this means when you shrink a panel in both dimensions, you get much much less power. But these IXOLAR panels are 25% efficient which is crazy! And not only that. they claimed to work fine in partial shade or even indoors which is something that other monocrystaline and polycrystalline cells tend to struggle with.", "51" ], [ "You will notice in the video that I actually have another photopopper using very similar parts but I used an amorphous cell for that one because I wanted it to work indoors (where amorphous cells shine) and I was still unaware of how good these monocrystaline cells had become. Again, you can see for yourself in the video, but the new cell is smaller than the old one, AND it pops around twice as fast indoors! Though this may also have something to do with the lower trigger voltage for this new bot =P.\n2. This point also ties into the solar panel power conundrum but I actually wanted this guy to move like bigger photopoppers so I was happy to sacrifice some miniaturisation for good functionality and again, I think this project achieved that. The other examples either wouldn't move too well or are still a little big but I really wanted to try make this guy as similar as I could to bigger photopoppers...just smaller! I could maybe have used smaller parts like some BPW34 cells, and some more clever circuitry/special motors to deal with lower voltage, really Im not sure, but more than anything I really just wanted this guy to be as small as possible and still move \"properly\"\nPhotovore here on instructables using a flexible amorphous cell and vibration motors:\nhttps://www.instructables.com/Nano-Photovore-BEAM-...\nAnd a great, albeit short, write up on a much more similar photopopper to this one:\nhttps://www.fetchmodus.org/projects/beam/photopopp...\nA super cool example using 8x BPW34 cells and an aluminium cap. Seriously, if you haven't seen <PERSON> videos check this out! Such incredible production value... but still a little big for my liking ;).\nhttps://www.youtube.com/watch?v=3RKTKfLhuPE\nAll of these were great inspirations for if this was even feasible as well as for specific parts (I will touch more on components in the next step).\nStep 1: Parts\n2x Voltage monitors: MCP112-195\nFor this particular photopopper I chose to use a voltage monitor that triggers at ~1.9V, with the added voltage drop in the diode and the voltage added by the photodiodes, this means that the circuit triggers when the storage cap reaches around 2.3V. In my previous attempt I used MCP112-270s that trigger at 2.7V which meant the capacitor needed to charge to around 3.1V! This is unnecessarily high for the motors I used but may be right depending on your other component choices.", "832" ], [ "How to Make a Driftwood Mood Lamp With Infrared Remote Control (using Arduino, an ATtiny85 and an Adafruit NeoPixel Ring)\nIntroduction: How to Make a Driftwood Mood Lamp With Infrared Remote Control (using Arduino, an ATtiny85 and an Adafruit NeoPixel Ring)\nI wanted to make a lamp from some old aquarium driftwood that was lying around, where the colours could be selected using an infrared remote and that would run on USB power using the small powerful ATTiny85 chip.\nThe design allows the user to choose from warm colours (reds, purples, oranges), cool colours (greens and blues) or specific colour choices. A total of 9 different selections. It also has adjustable brightness settings.\nSupplies\nEquipment needed as follows:\nFor base:\n* Old pieces of wooden patio decking\n* Gnarled driftwood\n* Wood glue\nFor electric circuitry:\n* An Arduino\n* Breadboard\n* Adafruit Pixelring (12 LED variant)\n* Infrared remote and receiver\n* Capacitor 100-1000 uF and atleast 6.3v\n* Resistors (470 ohm) and (4.7k ohm)\n* ATtiny85\n* Sparkfun ATtiny Programmer\n* Micro USB power source\n* L-Headers\n* USB extension cable (here)\n* Button switch\n* Wire in different colours\n* Heat shrink wrap\n* (Note I have created a PCB that makes the project neater. I have shown this at the end.)\nTools needed:\n* Small router for base edging\n* Table saw\n* Soldering iron and solder\n* Dremel tool\nStep 1: Make the Base\nThe base is made from two pieces of old patio decking we had lying around.\nStart by cutting off the edges using a table saw, leaving the width of both main pieces of wood at 8cm each (meaning removing 1.5cm from each side). This should leave you with two pieces of wood 16cm by 8cm. Obviously adjust this as needed based on the width of wood available.\nThen glue those two pieces together to form a 16cm x 16cm base.\nNext glue the offcuts to the base (per the picture) having cut the corners to 45 degrees.\nThis will allow enough depth to fit all the electronics into, later in the project.\nFinally shape the edges with a router to give an elegant finish on the upper side.\nStep 2: Add the Pixel Ring, Infrared Receiver and USB Power Source\nNext, drill three small holes to allow the legs of the infrared receiver to connect from the surface to the underside of the project.\nAlso cut three more holes in the correct position for the pixel ring (the points you need to connect are 5V, GND and data in).", "769" ], [ "Ignore data out for this project.\nSolder wires to the three legs of the IR receiver and also the pixel ring.\nFinally cut a hole using a Dremel to allow a micro USB extension to be fitted (the one I used is shown in the image and goes from female (with a flush fitting) to male).\nStep 3: Test the Circuit on a Breadboard Using an Arduino\nI used an arduino micro for testing but use any you have to hand.\nThe wiring is as follows:\n* IR receiver signal wire to Pin 5 of micro arduino\n* Connect Pin 9 of Arduino to Pixel ring data in wire via a 470 ohm resistor (suggested in best practice guide from Adafruit. See here for details.)\n* All other lines connected to 5v and GND with a 100-1000 uF (atleast 6.3v) capacitor between the lines. I used a 1000uF 16v variant.\nNext ensure that you know the correct codes from the Infrared transmitter so that you can code the buttons to do what you want them to do.\nTo do this follow the instructions shown here. Note the need for the IRremote.h library to be added in the Arduino IDE. The result will be that you will have an accurate list of codes for each button on your remote.\nThen use the following code ensuring that you change the RGB colours to the ones you want and amending the \"Define Key\" section to be correct for your IR remote.\nAlso note that both the IRremote.h and Adafruit_NeoPixel.h libraries are needed for this code. You can add these in the Arduino IDE Manage Library tool.\nThe code does something quite simple:\n* Buttons 1-5 just show single colours.\n* Button 6 to 8 cycle though colour combinations.\n* And button 9 runs the lovely Rainbowcycle sequence.\n* Button 0 then turns the LEDs to Black.\n* Finally the right and left keys increase or decrease the brightness.", "991" ], [ "LED Juggling Knives\nIntroduction: LED Juggling Knives\nThis project was inspired by one of my friends, who is an avid juggler. He was looking for glow in the dark juggling balls and I wanted to try my hand in building it. As I worked through the design I realised that it would be much easier to build knives instead of juggling balls and I moved forward with that. With my knowledge of the 4017 IC, I decided to add a bit of flourish to the lights, which are now in the form of LEDs, and that is how I ultimately ended up with this project.\nA set of juggling knives that can be also used in the dark for better visuals.\nThe LEDs are lit in a sequence, just like a led chaser. This is done by a 555 timer circuit in Astable mode combined with a 4017IC. The housing is relatively simple, and it was 3D printed.\nThis is a relatively challenging project to build with a lot of components required.\nSupplies\nNote: The following supply list covers the making of 3 juggling knives, as all juggling knives usually come in sets of three. If you want to build only 1, you can divide the quantity by 3.\nCircuitry BOM:\n1) 3 x NE555 IC + 8 pin IC holder (link)\n2) 6 x IN4007 Diodes (link)\n3) 3 x 4.7k Ohm resistor (link)\n4) 3 x 3.3k Ohm resistor (link)\n5) 3 x 4.7uF 10V electrolytic capacitor (link)\n6) 3 x 40mm by 50mm Perf Board. (Any size bigger than this is fine. You can trim it down later) (link)\n7) 2 x Male to Male Jumper Cable 40pcs. (link)\n8) 3 x 4017 IC + 16 pin IC holder (link)\n9) 3 x 10k Ohm resistor (link)\n10) 25 x 5mm LEDs in Red colour (5 are extra just in case) (link)\n11) 25 x 5mm LEDs in Blue colour (5 are extra just in case) (link)\n12) 25 x 5mm LEDs in Yellow colour (5 are extra just in case) (link)\n13) 3 x 9V Battery + connecting clips (link)\n14) 12 x 3mm Dia 20mm long bolts (link)\n15) 3 x 3mm Dia 6mm long bolts (link)\n16) 3 x Tactile latch switch (link)\nTools and Equipment:\n1) Soldering Iron + Soldering wire\n2) Desoldering pump\n3) Pliers\n4) Wire cutters + Wire Strippers\n5) 3D printer or access to a 3D printing service provider\nStep 1: Understanding the Circuit (555 Timer)\nThere are two parts of this circuit. 555 timer and 4017 IC. I will be exploring the former in this step. You can ignore this step if you are familiar with the 555 astable circuit.\n555 timer circuit\nThis circuit is a very common favourite of all electronics geeks. The schematic for the circuit can be seen in the first image.", "982" ], [ "Here is a link to the website where I got the circuit image from https://www.electronics-tutorials.ws/waveforms/555...\nFor this project, the circuit is wired up in an astable configuration. This means that the voltage output of the chip alternates between high and low at a constant frequency. The voltage output vs time graph of this circuit can be also seen in the image.\nIt is a square wave. Essentially the circuit produces pulses at a constant rate. This can be used to make an LED blink. The frequency of the pulse can be controlled used the values of the two resistors and the capacitor. These are respectively R1, R2, and C1 in the image. The equation used to calculate the frequency from these values has been given in the equation.\nThe final term is the duty cycle. It is the percentage of time for which the output is high. This can be also calculated with the equation in the image. Unfortunately, if the duty cycle is too high it leads to bouncing (link) or the connecting circuit can't even detect the pulse/low period.\nTo rectify this issue, this circuit has an additional 2 diodes compared to the conventional circuit. This is to make the duty cycle more even 50%-50% between on and off. (link)\nStep 2: Understanding the Circuit (4017 IC)\nThe 4017 IC works with the 555 timers.\nThe 4017 IC has multiple output pins: pins 1-7, 9, 10, and 11. Each of these output pins is set in a sequence as shown in the image.", "552" ] ]

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[ [ "Short answer:\nI suspect that so long as your pump is a positive displacement pump (ex: the \"vibratory pump\" or \"rotary vane pump\" as described in this webpage about espresso pumps) and is sized to output the flowrate you desire, then you only need a discharge valve or an appropriately designed flow restriction device (ex: a restriction orifice or your \"pressurized filter basket\").\nIf you need to reduce flowrate of a fixed-speed positive displacement pump yet maintain a controlled pressure, read on about installing a recycle line.\nLong answer:\nControlling mass flowrate and pressure through a pressure vessel (an espresso machine) is possible. I'm not an expert in espresso machines but I am somewhat familiar with the equipment needed to carry out the chemical engineering unit processes of solid-liquid extraction (ex: making espresso); I'm used to larger machinery.\nPump\nYou need a pump that can is capable of providing more than the maximum desired flowrate at more than the maximum desired pressure. A quick search for espresso pumps brings up this page about rotary and piston pumps, both positive displacement types. These pumps tend to output constant flowrate no matter the output pressure (they may still output less due to seal leakage and power limits of the motor).\nIf your pump isn't a positive displacement type, there are engineering methods that use \"pump curves\" as <PERSON> described to take into account quirks about other pump types (ex: centrifugal). However, no matter the type of pump used, as long as sufficient pressure and flowrate capacity in the pump is available, I know of three methods for controlling the pressure and flowrate through the system:\n1. Speed control\n2. Discharge control\n3. Recycle control\nYou will need at least two of the three.\n1. Speed control\n\"Variable Frequency Drive\" or, VFD, is a way to adjust the speed of the pump's rotating elements. Slower generally means less flow rate and pressure.\nFor your application, I imagine this would be an electronic module that adjusts the frequency and voltage of the alternating current electricity that powers your device. In the U.S. it is probably a frequency of 60 Hertz (Hz) at 120 volts of alternating current (VAC). I am not finding many hits on searches for variable speed espresso pumps so perhaps this type of control isn't popular.", "568" ], [ "This doesn't surprise me since adjusting frequency of power requires complex electronics.\nUsing a VFD is like adjusting your pump size without having to buy a new pump.\n2. Discharge control\nThis type of control involves restricting flow leaving the pressure vessel with an adjustable valve. Generally, when the valve is more closed, an increase in upstream pressure and reduction in flowrate through the system results.\nThe \"pressurized filter basket\" you mentioned in a comment on another answer sounds like it may fulfill the role of a discharge control. However you decide to restrict discharge flow, the discharge valve position (or orifice sizes of the basket?) will have to be adjusted in tandem with the other control method you select (Speed control or Recycle control) in order to achieve a desired pressure and flow through the pressure vessel.\n3. Recycle control\nThis method of control involves sending a portion of the flow leaving the pump or pressure vessel back into the inlet of the pump.\nIn your application, this may be achieved by installing two tees:\n1. A tee on the high pressure piping at the vessel or pump outlet\n2. A tee on the low pressure piping at the pump inlet.\nThen, you connect the two tees with a length of pipe containing a flow-restricting valve; this is a \"recycle line\". When the pump runs, some amount of fluid continuously recirculates if the recycle line valve is open. As the valve closes less fluid is permitted to recycle and the flow of fluid out of the system increases (provided the discharge control valve (if present) is somewhat open).\nRecycling fluid wastes some energy since fluid is pressurized by the pump and then depressurized at the recycle valve without leaving the system. The wasted energy heats the fluid somewhat. Recycling fluid might be desired if a limited supply of water is available or more extensive leaching of the coffee grounds bed is desired.\nMaintaining pressure and flowrate\nAs I mentioned before, if you have a pump that can output more than the desired flowrate at more than the desired pressure, then two of the three control methods will be necessary to maintain pressure and flowrate within the pressure vessel. This is the result of what in chemical engineering is known as a \"degrees of freedom analysis\". You will notice this phenomenon if you set up your system in a process simulator (ex: DWSIM (FOSS), VMGSIM (proprietary)) and fix pressure and flowrate of the pressure vessel.", "568" ], [ "Here's a diagram that I believe depicts your situation.\nI am concerned that this is overly simplifying the problem.\nYou're probably fine but it may be useful to review assumptions tied to that equation and your system.\nIdeal gas law.\nThe equation appears in API 520 Part 1 9th Edition (2014) on page 56 under section 5.6 Sizing for Gas or Vapor Relief which assumes that \"the pressure-specific volume relationship along an isoentropic path is well described by the expansion relation,\"\n$$PV^k={constant}$$\nwhere\n$k$ : is the ideal gas specific heat ratio at the relieving temperature.\nOr, in other words, that the gas is an ideal gas.\nThe document cautions that this assumption may not be valid if the compressibility factor (a.k.a. \"Z-factor\") falls outside the $0.8<Z<1.1$ range, as may be the case for high pressure conditions, high molecular weight gasses such as $CO_2$ or ${H_2}{S}$, or low temperatures. Compressibility is a measure of the \"non-ideality\" of a gas and is a function of both pressure and temperature.\nBased on your use of the ratio of specific heat $n=1.32$, it seems you are assuming the fluid is methane (the primary component in natural gas transmission lines). Use a process simulator / equation of state calculator to calculate the compressibility or calculate it manually such as with the method described in the GPSA Handbook (ex: GPSA 12th edition, Section 23 \"Physical Properties\", page 23-10, \"Z-FACTOR FOR GASES\") to confirm the ideal gas assumption is still valid.\nIf the gas cannot be assumed to ideal, then API 520 Part 1 provides a numerical calculation method in Annex B. The choked flow pressure drop is found as a side effect of identifying the maximum \"Mass Flux\" from a numerical integration process that uses a set of pressure, temperature, and specific volume values describing the state of gas at different points along an isentropic expansion (you'd use a process simulator / equation of state calculator to get these values).\n$$G^2 = \\left[ \\frac{- 2 \\cdot \\int^P_{P_1} v \\cdot dP}{v^2_t} \\right]_{\\text{max}}$$\nwhere:\n$G$ : is the mass flux (mass flow per unit area) through the nozzle, [$\\frac{kg}{s \\cdot m^2}$]\n$v$ : is the specific volume of the fluid [$\\frac{m^3}{kg}$]\n$P$ : is the stagnation pressure of the fluid [${Pa}$]\n$1$ : is the fluid inlet condition to the nozzle\n$t$ : is the fluid condition at the throat of the nozzle where cross-sectional area is minimized (the integral term corresponding to maximum mass flux)\nThe pressure drop at choke flow ($P_1 - P$) is found when additional terms from the $\\int^P_{P_1} v \\cdot dP$ integral slices don't cause $G$ to rise any more.\nOr you could buy commercial software and trust that they perform the non-ideal gas calculations correctly.\nOne-phase gas flow\nThe equation assumes one-phase gas flow.", "568" ], [ "If two-phase flow is present then a different set of equations are required to calculate the critical pressure ratio (see Annex C in the document).\nRestriction diameters\nI am having a hard time imagining a plausible scenario in which your system would be useful unless it contains a valve of some sort on the $D_1$ diameter pipe so the amount of gas flow to the second pipeline can be controlled. If a valve is present to perform this task, make sure to identify the location of the tightest flow restriction when designing the system. For example, if you are using a a ball valve, then make sure you know if it's a restricted port (\"RP\") or a full port (\"FP\") valve. If you're installing a pressure relief valve, make sure to reevaluate the sizing equations based on the actual orifice areas (\"flow areas\") and certified capacity values (\"coefficient of discharge\") provided by the manufacturer for valves they quote you (see the NB-18 \"Redbook\"). Beware erosion issues that can alter the pipe inner diameter.\nSummary\nIf you assume the gas is an ideal single-phase gas, then yes, the calculation of the pressure drop needed to achieve choked flow conditions is simply the equation for critical pressure ratio you provided. Otherwise, things get complicated.", "568" ], [ "Designing a pneumatic system for consistent pressure/flow\nFellow engineers, I need your help in improving my design for a pneumatic system for maintaining a constant supply of at least 90 PSI and 20 CFM for a particle analyzer with stringent air requirements. Its expected to draw air every 2 seconds. Here's the breakdown of the components used in the setup (in this order). Picture attached.\nA: Bulk water separator. This should help with removing moisture from the air because our plant air is heavily moisture-laden at times.\nB: Particulate filter: 0.01 micron air filter to ensure clean air, free from particles.\nC: Desiccant air dryer: Heat-less desiccant dryer for dry air. -40 C pressure dew point to ensure that there is no further condensation beyond this point and the air stays dry till it makes its way all the way to the analyzer. The dryer is rated for an inlet flow of 45 SCFM. I up-sized it because this is a heat-less dryer so a certain percentage of the air going in to the dryer will be used to regenerate the desiccants as well.", "842" ], [ "The dryer has an in-built filter that will prevent any of the desiccants from leaving the dryer.\nD: Globe valve: This is to contain the flow rate coming out of the dryer. This was suggested to me by another engineer. Since we are filling up a large tank, the air coming out of the dryer could potentially exceed the rated flow rate of the dryer which could damage the desiccants.\nE & F: Check valve and booster pump in parallel. The booster pump is meant to charge the receiver tank to a pressure of 95 - 100 PSI. The check valve is there to reduce the charge time by allowing air to pass through up to the inlet pressure. This could help take some of the burden off of the booster pump so that the pump only cycles when the tank pressure needs to be raised to setpoint.\nG: Air receiver tank: This will help create a reservoir of air that will ensure that the analyzer never has to wait for air. The tank is rated for 200 PSI but I won't be charging it more than 100 PSI. Still debating if I should go with a smaller tank because 80 gallons is an awful lot of volume for the booster to fill.\nH: Filter: To get rid of any of the remaining particles and oil vapors left in the system.\nI: Pressure regulator: To maintain the desired pressure for the equipment\nJ: Equipment - Particle analyzer.\nAny suggestions on improving this design?", "842" ], [ "How do I find out which compressor would fulfill my volume flow rate requirements based on Free Air Delivery as the only volume flow rate given in the catalogue?\n1. Calculate the mass flow rate of air given your required duty. You can do this by looking up or calculating the density of air, $\\rho_\\text{out}$, at your outlet conditions ($300 \\space \\frac{\\text{ft}^3}{\\text{min}}$ at $18 \\space \\text{psig}$ and $T_\\text{out}$) and then dividing your volumetric flow rate by this density.\n$$\\dot{m}=\\dot{V}\\text{out} \\cdot \\rho\\text{out}$$\n1. Convert mass flow rate $\\dot{m}$ to standard volumetric flowrate, $\\dot{V}\\text{std}$, (probably $\\text{SCFM}$, or Standard Cubic Feet per Minute in your case) since this is the number vendors use to rate their compressors. You can do this by dividing the mass flow rate by air density at standard conditions, $\\rho\\text{std}$.\n$$\\dot{V}\\text{std}=\\frac{\\dot{m}}{\\rho\\text{std}}$$\n$$\\dot{V}\\text{std}=\\dot{V}\\text{out} \\cdot \\left( \\frac{\\rho_\\text{out}}{\\rho_\\text{std}} \\right) $$\n1. Provide this standard volumetric flowrate along with:\n2. available suction pressure and temperature\n3.", "842" ], [ "required discharge pressure and temperature (note: often air compressor packages come with cooling options since compressing heats up air)\n4. utility power details (3-phase 240 VAC? continuous or intermittent duty?)\nHere's an example setup worked out:\nMy process simulator (DWSIM 5.8) gives $\\rho_\\text{out}=0.163758 \\space \\frac{\\text{lbm}}{\\text{ft}^3}$ for $T_\\text{out}=80^{\\circ}F$ (?) and $P_\\text{out}=32.7 \\space \\text{psi}$ (this is $18\\space\\text{psig}$ assuming atmospheric pressure is $14.7\\space\\text{psig}$)\nIt gives $\\rho_\\text{std}=0.0763781 \\space \\frac{\\text{lbm}}{\\text{ft}^3}$ for $T=60^{\\circ}F$ and $P_\\text{out}=14.696 \\space \\text{psi}$ (probably standard conditions in United States)\nPlug it all together and you have:\n$$\\dot{V}_\\text{std}=\\left( 300 \\space \\frac{\\text{ft}^3}{\\text{min}} \\right) \\cdot \\left( \\frac{0.163758 \\space \\frac{\\text{lbm}}{\\text{ft}^3}}{0.0763781 \\space \\frac{\\text{lbm}}{\\text{ft}^3}} \\right)=643.21317 \\space\\frac{\\text{ft}^3}{\\text{min}}$$\n$$\\dot{V}_\\text{std}=650\\space\\text{SCFM}$$\nNote: This value is only valid for the exact pressures and temperatures I assumed. You didn't provide an outlet temperature so I filled one in. Also, I didn't take pressure drop across the ducting into account (I simply used $18 \\space\\text{psig}$).\nWhat would be the best system to change the pressure of the compressor (116 psi) to the required pressure (18 psig). How can I control the pressure while achieving the required flow rate in the system. (Is the varying cross sectional duct with pressure regulation valves the best option)?\nIf you purchase a compressor that has a much higher maximum operating discharge pressure (ex: the $118 \\space\\text{psig}$ screw compressor you mentioned), then you can use a pressure regulator (which also would have to be sized for your mass flow rate and compressor outlet conditions) to reduce the pressure to that needed by your duct system. You'll also want to make sure a pressure relief valve (sometimes included with compressor packages if you request one) capable of relieving the maximum flow rate of air back to atmosphere in order to prevent equipment damage or injury in case accidental block-in causes dangerous pressure release (especially important with positive displacement compressors like a screw compressor).", "842" ], [ "It's correct to say that the temperature of the air in the jet coming from the neck of the bottle will be less than the temperature of the air in the bottle. The temperature of the air in the bottle will also be a little higher than the temperature of the outside air. The question is, will both the temperature and relative humidity of the jet air be sufficiently low to result in a net \"comfort zone\" in the room.\nThe \"comfort zone\" is a region of ambient air temperature and relative humidity that induces a comfortable feeling, and it has been mapped out by ASHRAE (American Society of Heating Refrigeration and Air Conditioning Engineers). Such data can be found for instance at https://www.dartmouth.edu/~cushman/courses/engs44/comfort.pdf\nI assume this device is meant only for Summer months, when outdoor humidity and temperatures are very uncomfortable. In order to work then, the device must deliver air to the room that will result in the temperature and humidity space according to the ASHRAE standard.\nIt's clear that the temperature of the jet air exiting the bottles will be a little lower than the temperature of the air in the bottle. That's simply because the expansion process through the nozzle is roughly isentropic. It's very likely that, for normal outside atmospheric conditions, the air pressure in the bottle will exceed room pressure only slightly. That's because the pressure in the bottle can be greater than the air pressure in the room only when outside wind collides with the bottles. Such a collision converts the kinetic energy of the wind velocity to a stagnation pressure. For normal wind speeds, however, this increase in pressure is small.\nThe velocity of the air jet into the room will thus be small, and the net temperature difference between outside air and air jet velocity will be small. Considering also that when the air jet mixes with room air, it's kinetic energy is dissipated, being converted to heat.", "108" ], [ "The net effect is that the final temperature of the jet air after it mixes with room air will be slightly elevated above its temperature when it exits the bottle. The conclusion here is that there can be only a minimal sensible cooling effect from this device. Most importantly, sensible cooling is only part of the air conditioning process, and the real question is what's the story with relative humidity.\nOften the most important process of air conditioning is the removal of water vapor from the air. The ASHRAE graphs show that the relative humidity necessary for comfort is often much less than the relative humidity present in Summer outside air. What happens to the water vapor (absolute humidity) of the air that's pushed through these bottles? Unfortunately nothing much.\nIn the vast majority of air conditioning processes, water vapor must be removed from the outside air before it can become comfortable for humans. Water removal is usually the most intensive process in air condition, not the reduction in (sensible) temperature. This device offers little mechanism for the removal of water vapor. The very slight increase in bottle pressure and the relatively low pressure drop encountered by the air in moving through the bottles ensures that the water vapor in the outside air remains in the air pushed into the room. If the jet air temperature would be lowered to a value below the dew point of the outside air, condensation would remove some of this water vapor. It's very unlikely that such a device could accomplish such low temperatures, for the reasons already explained. The net result is that this device pushes more water vapor into the room - not a very good means for conditioning outside air for comfort.\nBottom line is that for much of the typical Summer months in areas that require air conditioning, this device will not be able to produce a comfort zone, as defined by ASHRAE standards.", "108" ], [ "It's important for mechanical engineering students to get what we old timers describe as an “intuitive feel” for their subject. Luckily such is possible in this field, but not always in other fields, such as in Quantum Mechanics. Here's my suggestion for such an intuitive feel.\nMany of the answers give “correct” suggestions, but I don't see in any of them a way presented for the student to understand the physics that occurs as steam is giving up its internal energy in exchange for useful work.\nYes, it's due to the fact that latent heat is involved and that latent heat is orders of magnitude larger than sensible heat, or potential energy of compression, as you would have with using air as the working fluid. With compression of air, there's the added difficulty to hold onto all the energy put into compression. Compression increases the temperature of the air, and if the air storage tank isn't insulated, you will lose much of the compression energy in the form of heat to the environment.\nHere's the crux. Steam is usually introduced into piston engines and turbomachinery in the supersaturated state. In this state, it contains energy in a way similar to compressed air: there's no phase change. Thus, in the first moments in its travel through the machinery, it gives up its enthalpy (the best measure of energy transferred) just like compressed air does, until it begins to condense, which will occur when its pressure and temperature allow it, as it flows through its change of state within the machinery. With condensation, latent energy is released, and that “extra” energy can be intuitively visualized as a way for the liquid-to-vapor transition to add to its volume, with a tendency to increase its pressure above the pressure that it would experience without the phase change. As the steam flow continues down to lower pressures, more latent heat is given up, effectively keeping it's pressure at higher levels than it would be without the change of phase.\nThere's a very complicated relationship among the actual pressure experienced, the actual temperature experienced, and the amount of liquid water formed. There can be no latent energy release without the formation of liquid water, and the liquid water can cause damage to turbomachinery.", "568" ], [ "Thus the process is controlled and by the time the steam exits the machine, very little actual liquid water is present. It's a bit magical.\nAs some others point out here, that exiting steam is introduced to the condenser, which causes a partial vacuum in the condenser, increasing the overall pressure difference across the machine. When the steam enters the condenser, it's “quality” is relatively low. Quality is the mass fraction of vapor to liquid in a saturated fluid. Zero quality is all liquid. 100% quality is all vapor. And also as pointed out, the liquid water leaving the condenser requires much less energy to pump up to the boiler pressure, than if it were in gaseous form. That's because water is nearly incompressible, and work done is force times distance. With very little distance, there's little work done.\nFrom this view, one can see very easily that latent heat is a very important aspect to the use of steam as a working fluid. It takes much energy to vaporize liquid, but you get much of that energy back in the expansion process. Latent heat can be viewed as a large bucket, enabling you to carry a large amount of energy to the workings of the machine. With air, there's no such mechanism and you can't carry nearly as much energy to the machine.", "479" ], [ "I understand your setup as follows (in flow direction):\n* compressor with cutout set to 150 PSI\n* tank (T1) rated for compressor, with safety valve\n* (planned) pressure regulator (PR)\n* additional tank (T2), rated 120 PSI, with safety valve\nIf this is so the safety valve of the second tank will protect you unless you tinkered with or replaced this safety valve.\nNow, for the planned pressure regulator, check the flow rate you need and what the compressor delivers. Find the pressure differential ($\\Delta p$, I'd expect 0.5 bar / 7.3 PSI) of the PR at this flow rate. 120 PSI + $\\Delta p$ should be below the cutout point of the compressor, or you wont fill your T2.\nAt startup, the compressor will fill T1, at ~127 PSI (or whatever depending on the PR) T2 will fill until 120 PSI are reached, then PR will close, pressure in T1 reaches cutout point.\nDepending on the cutin point of the compressor and relative sizes of T1 and T2 you may get frequent on/off cycles. PR is an additional pressure loss in your system.\nThe ultimate problem you want to solve appears to be frequent, noisy runtime of the motor.", "568" ], [ "An additional tank won't change the total runtime for a given air demand much, at best it will make longer uptimes and longer downtimes (a good thing in itself IMO).\nIf someone tinkers with the PR, the worst I see happening is the safety valve venting provided no one tinkered with the safety valve and inefficient operation of the compressor.\nHowever I'd advise a preset pressure regulator.\nThoroughly check if the setup I assume is indeed what you have. Wait with building the thing until the hive mind here had the time to check my reasoning and find possible flaws.\nIn the long run, a compressor station sized for your application may be more economical.\nETA: The cutin point for the compressor is stated to be at 120 PSI, with the PR set to 120 PSI it is unlikely the pressure in Tank 1 will fall to 120PSI after the initial filling. See if your tools can operate at 100 PSI: 100 PSI in T2 + loss in PR = approx. 107 PSI + plus some safety to account for inaccuracies should be below the cutin point (if that can't be adjusted).\nLet me restate that you should not, in any way, fiddle with the safety valves. Safety aside, for the setup to work you need a lower pressure in the second tank.", "35" ], [ "Why do the bubbles in the water cooler get larger as the level gets lower?\nI have a typical office water cooler that uses a 19 liter bottle as a reservoir. The bottle is inverted on the base of the cooler with its neck below the water level in the cooler's reservoir. Air pressure (or more precisely, the reduced pressure above the water in the bottle) stops the water from flowing out once the level in the cooler's base reaches the bottle's neck.\nI have noticed that the size of the bubbles that enter the bottle as water is withdrawn is inversely proportional to the head (height of water in the bottle). For example, when the bottle is full of water (head ~50cm) it takes about 100 bubbles to fill the jug I use to collect the water. When the bottle is almost empty (head ~ 15cm) it takes only 20 bubbles to fill the same jug.", "1018" ], [ "The smaller bubbles when the bottle is full also enter faster (i.e. more frequently) but take longer, that is they continue for a longer period after I close the valve when filling my jug.\nData: Bottle full ~50cm head: about 100 air bubbles to withdraw about 2 litres water. Bottle almost empty ~15cm head: about 20 air bubbles to withdraw about 2 litres of water.\nI am at a loss to understand the physics behind this phenomenon.\nWater will run out of the bottle (and bubbles enter to replace the volume lost) until the water level in the reservoir (basically a bucket with a valve at the base) reaches the neck of the bottle inverted into it which prevents further air from entering. Water is then removed from the reservoir by opening the valve. This lowers the water level in the reservoir below the mouth of the bottle which allows more air to bubble in and water to flow out until the level again reaches the neck of the bottle. As the air is being drawn in at atmospheric pressure I am confused by the changing size and frequency of the bubbles.\nHere is a schematic drawing of the apparatus (apologies for the lousy drawing skills).", "1018" ] ]

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[ [ "This is an example of Art Imitates Life but that's not the TVTrope link you need.\nThis is the TVTropes link you deserve Object Ceiling Cling\nBasically, in storytelling, it's a comedic effect to have things stuck in the ceiling and maybe fall after.\nHowever, there are specific pencil references in that link:\nLive-Action TV\nAn episode of Coach featured <PERSON> in <PERSON>'s office throwing and sticking pencils up into the ceiling to the point it was literally covered in them. When <PERSON> kicks <PERSON> out of his office he slammed the door causing all the pencils to fall down.\nIn Dharma & Greg, episode 1, <PERSON> is shown in his new law office throwing a couple pencils at the ceiling. The camera pans up to show a couple dozen pencils already stuck in the tiles above his desk. Later, he throws one more pencil above his head, only to have all the others fall out of the ceiling onto him.\nHow I Met Your Mother: <PERSON>, <PERSON>, and <PERSON> are throwing pencils at the ceiling. One falls and bounces up <PERSON>'s nose, which <PERSON> calls a miracle.\nCombination of Live-Action TV and Real Life: Late Night with David Letterman.", "5" ], [ "Viewers know of <PERSON>'s tendency to flip pencils up out of view coming out of commercial break. Studio audience members get to see the result; the fake acoustic ceiling above the desk is peppered with pencils, and his accuracy is epic (I went to half a dozen shows and he didn't miss once).\nThe X-Files: episode \"Chinga\", <PERSON> spends his spare time throwing pencils into the ceiling over his desk.\nThe very last one is probably the one you reference in your question. HIMYM (the other show was probably contemporary to Castle) but Coach was late 80's and Dharma & Greg was early 90's\nThe link goes on further to\nReal Life\nKids in school launch pencils up at ceilings which have small holes just small enough for the pencil to stick in\nOffice workers who work in buildings with fake ceilings often throw pencils into the ceiling, as the fake ceilings are often as weak as cardboard. Parodied in [a] Bud Light commercial.\nIt is a visual cue of boredom, ennui; in Spanish we say \"ocio\" where in English there is a saying \"Idle hands are the Devil's tools\". Not sure where in the world you hail from, but there may be an international equivalent you are familiar with.", "900" ], [ "What rules govern how TV show opening credits are structured?\nI've always been curious what decides if a credit is in the opening or closing credits. It seems loosely that cast (in order of today's \"big name\" significance), directors and financiers get the front spots, and everything else appears later. But lately I've been developing some specific curiosities about how cast members are credited on TV shows.\nOpening credits seem to follow this rough outline:\nPart of \"opening credits\" video segment\n1. (optional) Major Actors\n2. Show Title\n3. Core Cast Actors\n4. Directors\n5. Producers\n6. (optional) Episode Title\n7. Episode Writers\nSubtitles over beginning of show, after opening video\n1. (Episode Title and Writers may appear here, instead)\n2.", "233" ], [ "Special Guest Actors\nI've probably missed a few things, and mis-ordered a few things. But, as I said, my main curiosity is about actor credits.\nTypically, there is little indication of which characters the core cast actors play. Sometimes their name is edited to appear along with an image of the character as an indictator, but sometimes there is no indication. As I've never seen anyone credited in both the opening and closing credits, that leaves the potential for core actors to never be directly associated with their character. This seems potentially problematic; is there a reason for this? Are viewers expected to know who's who?\nGuest actors sometimes are simply credited by name (and not being part of the opening video, this means they will never be associated with their character in credits). But often they are credited as \"special guest as character name\". This is quite helpful.\nThe thing I find really confusing is, sometimes the last few regular cast actors will get the guest actor treatment. I've seen opening video with \"and actor as character\" paired with an image of that character for an entire season. Why does this actor get special treatment?\nFinally, sometimes guest actors will be credited at the front following the opening video, sometimes they'll be credited in the closing credits. Are there rules for deciding who get's credited early or late?\nI've sometimes wondered if shows deliberately play with actor's name position to obfuscate plot arcs (\"you won't think we're killing of this character if their actor is still in the opening credits\", or \"you won't expect this recurring guest if we place their name in the closing credits\") and I've also wondered if there are thresholds for \"people appearing in XX number or YY percentage of episodes get placed here.\" But it's difficult to build a good sampling base for this. And season 7 of Stargate SG-1 kinda took a shotgun to my guesses so far.\nSo... Are there rules?", "233" ], [ "<PERSON> is indeed a character from the original Vertigo series, published as part of DC's darker, grittier comics.\n<PERSON>, the show forerunner and executive producer (along with <PERSON> and <PERSON>) have conceded that they could not do a one-to-one translation from comic to episode as that would make the series end rather quickly. We cannot rely on canon for an answer here, more than likely, as there only about 75 issues in total with 4 specials and a spin-off series.\nMy opinion (and I will try to defend it) is that this is yet another nod to \"The Big Lebowski\" (<PERSON>'s least favorite film by the <PERSON> Brothers). Towards the end of that film (no spoilers, hopefully), we are introduced to a group of individuals who dress in black and simply call themselves Nihilists because \"They believe in nothing\".\nThe connection to <PERSON> may be tenuous but the similarities are the following:\n* German origins - The Nihilists are of German descent and we know <PERSON> initially serves a German government agency.\n* Accent - just because someone is of German descent does not automatically mean they're gonna have a German accent. The choice to give both pronounced German accents is deliberate (a TVTrope, if you will).\n* Philosophy - the comments to the question are what prompted this answer as there are references to sadism, which is the enjoyment of inflicting pain. In a romantic setting, it requires the consent of another party who enjoys receiving pain in a BDSM arrangement (as poorly portrayed in Fifty Shades of Gray). This, however, is not what is taking place in this scene. <PERSON>, per the OP, is regaling Herr <PERSON> with a story about meaning, which is the antithesis to Nihilism. In asking her to remove her top and stick the butter under her chin, he is showing that a) he has no interest in her story b) demonstrating that his actions won't always have a purpose (as he might not believe in anything either) c) as someone who doesn't believe in things like morality or propriety, actions that might be deemed cruel to a casual observer are part and parcel to any conversation with him.\nThere are no pointless scenes in television, every minute (indeed every second) is paid for in actor salaries, wardrobe, makeup and post-production.", "663" ], [ "Whether the choices that are made make sense to each of us individually or to the audience as a whole is another topic altogether.\nUpdate after re-watching scene\nThis scene occurs in the Herr Star chronology after he's shown the video of <PERSON> using the voice of God super-power on <PERSON>, telling her to \"Sleep\" Everything else said above still stands, but with the additional context of <PERSON> being unimpressed with the footage, saying he's bored (after the floating pig incident) \"Since when is a woman obeying a man a superpower?\". The dinner scene then is him proving his own point. Power is not always supernatural, the daughter of the governor of Louisiana felt like she had to listen to what he said as he worked for the world's most powerful organization, with agents in 113 countries, all ready to do his bidding at a moment's notice. Would you refuse what he said?\nNext on the chronology, we do hear about his R-word fantasy with multiple prostitutes but through his battle with Cat popup ads, he accidentally reviews more of <PERSON>'s surveillance footage.\nOnce again, everything above stands but perhaps <PERSON> is a bored Nihilist searching for the same thing <PERSON> is - order in a world of chaos.\nOne more update - within the larger context\nI am getting tired of the phrase Nihilism because it's a weird word to type, like bananas, too many of the same vowel- I digress.\nIn their initial date, mentioned by the OP, <PERSON> was more than bored. He was baffled perhaps even offended by her story, perhaps the way she told it. The conversation starts with how important <PERSON> is and how his influence got them a reservation at a restaurant that was closed other than the two of them (and the staff, of course). <PERSON>, impressed with his masculine power/influence, tries to regale him with her feminine accomplishments of traveling and volunteering but it is the way she tells it that offends him. She begins with a condescending tone of someone who has achieve enlightenment and has to teach the ignorant \"The Way\" or some such (\"I was once like you were...\"). Indeed, what triggers the sequence of events that started this question and its lengthy answer (I'm sorry...", "663" ], [ "In order of appearance:\n1. <PERSON>\nTest subject between the pilot (KTMA-00- The Green Slime) and S05E12- Mitchell.\n<PERSON> as he appeared in S03E03- Pod People\n1. <PERSON>\nTest subject between KTMA-01- Invaders from the Deep and S10E13- Diabolik.\n<PERSON> was alone in the theater during the pilot so he wasn't technically a test subject at that point, though he did appear in the episode, unlike <PERSON>.\n<PERSON> as he appeared during the Season 7 intro\n1. <PERSON>\nTest Subject between KTMA-02- Revenge of the Mysterons from Mars and S10E13- Diabolik.\nAs mentioned above, <PERSON> didn't technically appear in the pilot episode, though a vaguely similar looking robot called \"Beeper\" did (in the host segments only):\nBeeper as seen in The Green Slime\n<PERSON> who voiced and operated Crow T. Robot during the first 8 series did not appear in Invaders from the Deep, and instead <PERSON> (who voiced and operated <PERSON> for the first 2 seasons) played <PERSON> and therefore <PERSON> was absent, first appearing as a test subject the next episode:\n<PERSON>, absent from a rare Invaders of the Deep clip\n<PERSON> as he appeared in the Season 7 intro\n1. <PERSON>\nSort of. <PERSON> joined <PERSON> & The Bots in the theater for S04E12- Hercules And The Captive Women, though she got bored and left after 5 minutes:\n<PERSON> shown at the left of the theater during Hercules And The Captive Women\nShe was also shown in the theatre during the KTMA season intro, though never during the episodes:\nThe original design for Gypsy shown in the theatre during the KTMA opening\n1. <PERSON>\nIn S04E16- Fire Maidens of Outer Space, <PERSON> & The Bots are visisted by a strange creature apparently from <PERSON>'s imagination, it's an exact copy but black, and eventually he begins playing tricks on everyone.", "167" ], [ "Several times he shows up in the theater to watch the movie and annoy the gang:\n<PERSON> in Fire Maidens of Outer Space\n1. <PERSON>\nTest subject between S05E13- The Brain That Wouldn't Die and S10E13- Diabolik.\n<PERSON> as he appeared in the season 5 intro\n1. Mirror Universe <PERSON>\n2. Mirror Universe TV's <PERSON>In S06E11- Last of the Wild Horses, the Mads perform a matter transfer experiment which winds up with <PERSON> & The Bots in a Mirror Universe, where Captain <PERSON> and <PERSON> are forcing <PERSON> and TV's <PERSON> to watch bad movies, and the first third of the episode features them riffing the movie:\n<PERSON> and TV's <PERSON> watching Last of the Wild Horses\n1. <PERSON>\nIn S08E21- Time Chasers, to fit in with the storyline of the movie, <PERSON> goes back in time and tries to warn <PERSON> not to take the job at Deep 13 which will lead to him getting marooned in space. Upon his return, <PERSON> discovers that all that's changed is now instead of <PERSON>, they've got his foul-mouthed, beer-swilling asshole brother, <PERSON> who riffs the middle third of the film:\n<PERSON> in Time Chasers\n1. <PERSON>\nThe final test subject was <PERSON>, in S09E13- Quest of the Delta Knights she's disappointed that she's been showing <PERSON> terrible movies for 2 years with no real results, so they switch places and <PERSON> watches the first third of the movie with them to try and work out how best to torment him in the future:\n<PERSON> in Quest of the Delta Knights\nSo all together, there were 10 different test subjects. There were also a couple of visitors to the theater who didn't actually watch any part of the movie:\n1. <PERSON>\nAfter <PERSON> has finished her investigation of the theater, she brings in \"Eggs\" from Facilitech to fix the Pain Leakage which has stopped Mike & The Bots from experiencing the Deep Hurting Pearl desires from these movies:\n<PERSON> in Quest of the Delta Knights\n1.", "167" ], [ "Sliding Doors\nIt’s the year 2002 and <PERSON> is riding the tail end of her peak. Newly released DVD Shallow Hal is out of stock at the local blockbuster so a 10 year old me is tasked with choosing between <PERSON>’s Shakespeare in Love and this. I chose <PERSON> in love then so now because there’s no alternate timeline I finally decided to see if I missed anything. Turns out I didn’t.", "378" ], [ "Watch Right Now Wrong Then for a much better example of this concept done well\nStray Observations\n- The ending(s) are awful. Like soap opera awful\n- the soundtrack slaps including <PERSON>’s Thank You over the credits\n- the main love interest’s one line is to make the same Monty Python reference and somehow it works every time. (?!?!)\n- <PERSON>’s hair in this is fantastic and so 90s. Her British accent though? Not so fantastic.", "952" ], [ "Bee Movie\nThis isn't a GoodFella. This is a BadFella!\nPart 1: <PERSON>\nIt's no coincidence that DreamWorks' first animated film they released starred <PERSON>. And the best way to describe Bee Movie is a <PERSON> movie not starring <PERSON>. But in 2007, <PERSON> was a man in his 70s. To a dude like <PERSON>, even he's too old to headline a non-Aardman film. So pick the next best thing: <PERSON>. <PERSON> may be a movie star/director, but <PERSON> had a big TV show and isn't that the hot thing? It gets better. A movie about a bee suing the human race sounds like a <PERSON> script right there.\nPart 2: <PERSON> New York Groove\nSeinfeld was the big show in the 90s, right behind the <PERSON> White House. <PERSON> was another 90s institution, hell-bent on seizing power. Since Antz, most if not all DreamWorks films come off like <PERSON> bringing New York to Middle America. The problem is, <PERSON> is an elite New Yorker. <PERSON> doesn't come off like a man with real grievances. He comes off like a man who donates to left-leaning and special interest groups because he does. Now I think he's a few steps above <PERSON> until further notice. But that doesn't say much.\nPart 3: Politically Incorrect <PERSON>?\nBut jovially leftist executives are one thing. Their movies are another.", "711" ], [ "Bee Movie is one of, if not the edgiest DreamWorks film. Shrek never had suicide pact jokes. The Prince of Egypt didn't deal in drag queen quips. Bee Movie is enjoyably politically incorrect to a certain degree. When's the last time I've heard an antagonist promote global warming? And the court's decision to shut down honey production actually has ramifications. And not just the ATF gaining a letter. <PERSON>'s \"smoking gun\" stunt triggers a dramatic potential famine. And simply returning to honey production is what the world needs.\nPart 4: Epilogue\nBee Movie is a weird film, but one thing I like about it is that it's not ashamed of itself, even when it easily could be. Is it inappropriate? To a degree. There are limits to being as edgy as possible. And <PERSON> strikes me as a man who doesn't care who he's being edgy to. He doesn't know his audience. Bee Movie is a film I'm conflicted on. It's a demonstration of DreamWorks' best and worst tendencies. Now which tendencies will entirely depend on the viewer. But in terms of standard DreamWorks, Bee Movie is not that bad.", "711" ], [ "Signs\nMy most notable Letterboxd review is a pan of Close Encounters. <PERSON>, who loves <PERSON> as we all do, wanted this to be his version of it. I think this one is way better.\nA broken man in an impossible situation relearns how to love and protect his family. <PERSON> crushed it with two great kid actors. Compared to a movie like Independence Day, this is basically a home invasion film.", "369" ], [ "It didn't have to be aliens, it could have been anything (except for the thematic reasons). <PERSON> is a tortured man just barely holding it together, which in retrospect turned out to not be a stretch for him. <PERSON> really didn't need to cast himself as the manslaughtering neighbor. Weirdly for a movie about an atheist preacher mourning his dead wife, this is kind of his funniest movie. It's really pretty cheesy but it works for me unlike Close Encounters.\nAlso, the shared memory people my age have of that footage of the birthday party being one of the most terrifying things in cinema is some sort of fever dream we all had. It's a tense moment but stop citing it as one of the scariest movie moments of all time.", "698" ], [ "The Collector\nThe Collector, The Rat Race, and Mouse Mania are three short live action/stop-motion hybrids created for a Disney jubilee SOV release. Not the Disney obsessive myself, I don't know about the other shorts on that tape, but the <PERSON>'s are nothing but brilliant.", "252" ], [ "As usual.\nA single file* with the 3 Jittlov's floats around somewhere. At the end you can see that this was screened as part of an episode of Shields and Yarnell. What happened to television…\n*Probably logging this all wrong because I can imagine that what I watched is similar to the Animato compilation.", "167" ] ]

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[ [ "As suggested by <PERSON>, you may want to check in the Math section. However, I want to point out one thing about how to handle the limit.\nI will assume that $|\\vec{k}|\\ne 0$. The first thing you want to do it separate each propagator into its real and imaginary parts. In general, $$\\lim_{\\delta \\rightarrow 0^+}\\frac{1}{E-E(q)+i\\delta} = \\lim_{\\delta \\rightarrow 0^+}\\left[\\frac{1}{E-E(q)}-i\\frac{\\delta}{[E-E(q)]^2 + \\delta^2}\\right],$$ where I multiplied top and bottom by the complex conjugate of the denominator, and disregarded the $\\delta^2$ in the denominator of the real part, since it'll just go away when you take the limit. Then you use the identity $$\\lim_{\\delta\\rightarrow 0^+}\\frac{\\delta}{[E-E(q)]^2+\\delta^2} = \\pi\\delta(E-E(q)),$$ that is, the Dirac delta. What you get is $$\\begin{split}&\\int d^3q\\,\\left[\\frac{1}{E-E(q)}-i\\pi\\delta(E-E(q)) \\right]\\left[\\frac{1}{E-E(|\\vec{q}+\\vec{k}|)}-i\\pi\\delta(E-E(\\vec{q}+\\vec{k})) \\right]\\ &=\\int d^3q\\,\\frac{1}{E-E(q)}\\frac{1}{E-E(|\\vec{q}+\\vec{k}|)} + i\\pi\\int d^3q\\,\\left[ \\frac{\\delta(E-E(q))}{E-E(|\\vec{q}+\\vec{k}|)} + \\frac{\\delta(E-E(|\\vec{q}+\\vec{k}|))}{E-E(q)} \\right]. \\end{split}$$\nNotice that, since I'm assuming $k\\ne 0$, the product of two Dirac deltas will have to vanish, because their arguments are never simultaneously zero.", "916" ], [ "You can easily evaluate the integral with the Dirac deltas. Recall that, since the dispersion is quadratic in $q$, you need to follow certain rules when you change variables. That gives you the imaginary part of the integral. I have no real advice on how to evaluate the real part $$\\mathrm{Re}{I(\\vec{k})}=\\int d^3q\\,\\frac{1}{E-E(q)}\\frac{1}{E-E(|\\vec{q}+\\vec{k}|)},$$ except to check that you actually need it. Depending on the problem you're solving, sometimes all you need is the imaginary part. On the other hand, I also recommend you check that both denominators in $I(\\vec{k})$ have $+i \\epsilon$, instead of one having $+i \\epsilon$ and the other $-i\\epsilon$. I say this because that expression looks like the skeleton approximation to a polarization bubble, which is the product of a retarded and an advanced propagator, in which case their imaginary parts have opposite signs.", "418" ], [ "You start by writing down the probability to find a particle at $y$ at time $t$ when it was at $x$ at time $0$, denoted as $K(y,t;x,0)$. You get this by solving the <PERSON> equation with the initial condition $\\psi(y,0) = \\delta(y-x)$. Then, $K(y,t;x,0) = \\psi(y,t)$. Thus, to solve this, we need to know the time development of $\\psi(y,t0$.\nLet us start with the simple example of a free particle. This is easiest solved in momentum-representation, obtained by Fourier-transforming $\\psi(y,t)$:\n$$\\psi(y,t) = \\frac{1}{\\sqrt{2\\pi\\hbar}} \\int dp exp(ipy/\\hbar) \\tilde \\psi(p,t)$$ For $\\tilde \\psi$, the <PERSON> equation gives $$\\tilde \\psi(p,t) = \\frac{1}{\\sqrt{2\\pi\\hbar}} \\exp \\left(-\\frac{i}{\\hbar} \\left[\\frac{p^2 t}{2m} - px\\right]\\right)$$ This can be inserted back into the equation for $\\psi(y,t)$.", "526" ], [ "The integral over $p$ can be solved exactly. The final result is $$K_\\text{free}(y,t;x,0) = \\sqrt{\\frac{m}{2\\pi i\\hbar t}} \\exp\\left(\\frac{im(x-y)^2}{2\\hbar t}\\right)$$\nNext step: The solution of the <PERSON> equation can generally be written as $$|\\psi, t\\rangle = \\exp\\left(-\\frac{iHt}{\\hbar}\\right) |\\psi,0\\rangle$$ with $H$ being the Hamiltonian of your system. Writing $H = T+V$, the general formula for $K$ becomes $$K(y,t;x,0) = \\langle y \\mid \\exp(-\\frac{i(T+V)t}{\\hbar}) \\mid x \\rangle$$ We use the Trotter-Kato Formula (which holds under certain conditions which I won't go into detail at this point. It allows us to write $$K(y,t;x,0) = \\lim_{N\\rightarrow \\infty} \\langle y \\mid \\left[ \\exp(-\\frac{iTt}{N\\hbar}) \\exp(-\\frac{iVt}{N\\hbar})\\right]^N \\mid x\\rangle$$ We insert the unity operator, decomposed as $1 = \\int dx | x \\rangle \\langle x |$ $N-1$ times, which gives us $$K(y,t;x,0) = \\int dx_1 dx_2 \\dots dx_{N-1} \\prod_{j=0}{N-1} \\langle x_{j+1} \\mid \\exp(-iTt/N\\hbar) \\exp(-iVt/N\\hbar) \\mid x_j \\rangle$$ Note that $V$ as an operator acting on $|x\\rangle$ gives just $V(x) |x\\rangle$. And $\\langle x_{j+1} | \\exp(-iTt/N\\hbar) | x_j \\rangle$ gives us just the contribution of a free particle, i.e. $$\\sqrt{\\frac{mN}{2\\pi i\\hbar t}} \\exp(\\frac{imN}{2\\hbar t}(x_{j+1} - x_j)^2$$.", "955" ], [ "This is a somewhat broad question, because there are a number of different Green's functions in quantum physics. Perhaps the simplest one is the resolvent Green's function for a single-particle system. Its definition is $$G(\\omega^{\\pm})=\\lim_{\\delta \\rightarrow 0^+}\\left[ \\omega \\pm i\\delta - H \\right]^{-1}\\equiv \\frac{1}{\\omega\\pm i\\delta - H},$$ where $H$ is the Hamiltonian. Ignoring the $\\delta$, and replacing $\\omega \\rightarrow E$, you can see how this relates to the time-independent <PERSON> equation: $$H\\left|\\psi \\right>=E\\left|\\psi \\right> \\longrightarrow \\left[ E - H\\right]\\left|\\psi \\right> = 0.$$ Basically, if you apply the operator $G$ to a solution to the <PERSON> equation, $\\left|\\psi_n \\right>$ with energy level $E_n$, you get a pole (the \"denominator\" vanishes) at $\\omega \\pm i\\delta = E_n$. That is, $$G_{nn}(\\omega^{\\pm})\\equiv\\left<\\psi_n \\right|G(\\omega^{\\pm}) \\left|\\psi_n \\right>=\\frac{1}{\\omega \\pm i\\delta - E_n},$$ has a pole. Then it is clear that the poles of (Tr = trace) $$\\mathrm{Tr}{G(\\omega^{\\pm})}\\equiv\\sum_{n}^{\\mathrm{all\\,states}}G_{nn}(\\omega^{\\pm}),$$ give you the full spectrum.", "526" ], [ "In fact, you can show that the quantity (Im = imaginary part) $$\\rho(\\omega)=-\\frac{1}{\\pi}\\mathrm{Im}{\\mathrm{Tr}{G(\\omega^+)}},$$ gives you the density of states of the Hamiltonian $H$.\nThe resolvent Greens function is valid for a single-particle system, but the concept caries over well to many-body physics, and thus to quantum field theory. However, the definition of the Green's function is not as direct in those cases. The Green's function is given by the probability amplitude that a particle will be added to the vacuum state at a time $t$ and state $n$, and that after time evolution it will be removed at time $t'$ and state $n'$: $$\\mathcal{G}(t',n';t,n)=-i\\left<\\Phi \\right|\\psi_{n'}(t')\\psi_n^\\dagger (t) \\left|\\Phi \\right>,$$ where the factor of $i$ appears just as a convention, and $\\left|\\Phi \\right>$ represents the ground state. This definition has a very transparent interpretation, because this quantity is the answer to the question: if in the quantum vacuum, which is (to quote <PERSON> favorite phrase) \"a boiling bubbling brew of particles popping in and out of existence,\" a particle were to pop into existence at time-state $(t,n)$, what is the probability (amplitude) that it would propagate to time-state $(t',n')$? There are a number of different versions of this type of <PERSON>'s function, each useful for a different thing. One thing all of these have in common is that handling them in this form is complicated, and it is much easier to work with their Fourier transforms $$\\mathcal{G}{n'n}(\\omega^{\\pm})=\\int\\mathrm{d}(t'-t)\\,\\mathrm{e}^{i(\\omega\\pm i \\delta )(t'-t)}\\mathcal{G}(t',n';t,n).$$ As you can see, a complex shift $\\delta$ is introduced here, which has to do with the convergence of the integral. This is precisely the origin of it in the resolvent Green's function.", "976" ], [ "Consider first the expansion of the electrostatic potential $\\Phi$ in a stationary situation $$\\Phi(\\vec{r}) = \\frac{Q}{4 \\pi \\epsilon_0 r} + \\frac{\\vec{d}\\cdot \\vec{r}}{4\\pi \\epsilon_0 r^3} + \\mathcal{O}(r^{-3})$$ Now let us shift our origin by $\\vec{a}, \\vec{R} = \\vec{r} - \\vec{a}$, where $|\\vec{a}| \\ll r$. The monopole term then gets expanded as $$\\frac{Q}{4 \\pi \\epsilon_0 r} = \\frac{Q}{4 \\pi \\epsilon_0 |\\vec{R} + \\vec{a}|} = \\frac{Q}{4 \\pi \\epsilon_0 R} - \\frac{Q(\\vec{a}\\cdot \\vec{R})}{4 \\pi \\epsilon_0 R^3} + \\mathcal{O}(R^{-3})$$ The dipole term is simply $$\\frac{\\vec{d}\\cdot \\vec{r}}{4\\pi \\epsilon_0 r^3} = \\frac{\\vec{d}\\cdot \\vec{R}}{4\\pi \\epsilon_0 R^3} + \\mathcal{O}(R^{-3})$$ Now let's take a look at the whole potential $$\\Phi(\\vec{r}) = \\Phi(\\vec{R}) = \\frac{Q}{4 \\pi \\epsilon_0 R} + \\frac{(\\vec{d}-Q\\vec{a})\\cdot \\vec{R}}{4\\pi \\epsilon_0 R^3} + \\mathcal{O}(R^{-3})$$ Note that this is (within the approximation) just a different description of the same potential as above. In other words, if you take a look at the same physical point, you will get the same value of $\\Phi$ independent of whether you are in the $\\vec{r}$ coordinates or the $\\vec{R}$ coordinates.\nNow let us denote the dipole defined with respect to $\\vec{R}$ as $\\vec{D}$ and compute $$\\vec{D} = \\int \\rho \\vec{R} d V = \\int \\rho \\vec{r} d V - \\int \\rho \\vec{a} d V = \\vec{d} - Q\\vec{a}$$ We then see that our shifted potential in $\\vec{R}$ coordinates can be written as $$\\Phi(\\vec{R}) = \\frac{Q}{4 \\pi \\epsilon_0 R} + \\frac{\\vec{D}\\cdot \\vec{R}}{4\\pi \\epsilon_0 R^3} + \\mathcal{O}(R^{-3})$$ which is exactly the multipole expansion that you would get if you started from the $\\vec{R}$ coordinates in the first place.\nI.e., multipole expansions are covariant with respect to coordinate shifts. It is possible to show that this applies to all orders with more and more terms trickling down from lower orders to higher ones, and you can even show covariance of the multipole expansion with respect to the whole <PERSON> group (with small translations).\nYou are now probably asking what is happening with your radiation formula then.", "649" ], [ "The trick is that the formulas you give will apply only in inertial frames. In particular, $\\vec{a}$ will typically be a constant shift. However, your radiation formula applies to oscillation magnitudes to which a constant $\\vec{a}$ will have subleading or outright vanishing contributions.\nConsider the dipole moment. We have $\\vec{D} = \\vec{d} - Q\\vec{a}$. Then you see that since $\\dot{Q} = \\dot{a} = 0$, we have $\\dot{D} = \\dot{d}$ and there is no extra term arising in the radiation formula from the shift.\nAs for the dipole magnetic moment, we have $$\\vec{\\mu}' = \\vec{\\mu} + \\frac{1}{c}\\vec{a} \\times \\int \\vec{j}\\, dV$$ It is a slightly more complicated argument why the extra term will be subleading.", "499" ], [ "So the aim is to solve the equation $(\\Box+m^2)\\phi(\\vec{x},t)=0$ for $\\phi$ ($m=0$ in <PERSON>'s example, but we'll leave it in). Note that (as <PERSON> writes) $$(\\Box+m^2)\\phi(\\vec{x},t)=(\\partial_t^2-\\vec{\\nabla}^2+m^2)\\phi(\\vec{x},t)=0\\tag{(1)}$$ Something you will get used to is flipping between differential operators in position space and their form in Fourier space. The Fourier conjugates of $\\Box$ and $\\Delta=\\vec{\\nabla}^2$ are namely $-p^2$ and $-\\vec{p}^2$, respectively.", "418" ], [ "To see how this works, consider the field expressed in terms of its $\\vec{p}$-space Fourier conjugate, which we will call $a_\\vec{p}(t)$: $$\\phi(\\vec{x},t)=\\int\\frac{d^3\\vec{p}}{(2\\pi)^3}a_\\vec{p}(t)e^{i\\vec{p}\\cdot\\vec{x}}.$$ Insering this into eq. 1 then gives \\begin{align} (\\Box+m^2)\\phi(\\vec{x},t)&=\\int\\frac{d^3\\vec{p}}{(2\\pi)^3}(\\partial_t^2-\\vec{\\nabla}^2+m^2)a_\\vec{p}(t)e^{i\\vec{p}\\cdot\\vec{x}}\\ &=\\int\\frac{d^3\\vec{p}}{(2\\pi)^3}(e^{i\\vec{p}\\cdot\\vec{x}}\\partial_t^2a_\\vec{p}(t)-a_\\vec{p}(t)\\vec{\\nabla}^2e^{i\\vec{p}\\cdot\\vec{x}}+m^2a_\\vec{p}(t)e^{i\\vec{p}\\cdot\\vec{x}})\\ &=\\int\\frac{d^3\\vec{p}}{(2\\pi)^3}(\\partial_t^2+\\vec{p}^2+m^2)a_\\vec{p}(t)e^{i\\vec{p}\\cdot\\vec{x}}\\ &=0 \\end{align*} So we find that the Fourier coefficients for each $\\vec{p}$ are solutions to the conjugate equation to (1): $$(\\partial_t^2+\\vec{p}^2+m^2)a_\\vec{p}(t)=0$$ which should be familiar as the differential equation for simple harmonic motion, solved by $a_\\vec{p}(t)=a_\\vec{p}e^{-i\\omega t}$ where $\\omega=\\sqrt{\\vec{p}^2+m^2}$ and $a_\\vec{p}$ is constant in time (but of course depends on $\\vec{p}$). The final step is to realize that $\\phi^\\dagger(\\vec{x},t)$ is also a solution to (1) (just take the Hermitian conjugate of both sides), so we arrive at the full general solution $$\\phi(\\vec{x},t)=\\int\\frac{d^3\\vec{p}}{(2\\pi)^3}\\left(a_\\vec{p}e^{-ipx}+a^\\dagger_\\vec{p}e^{ipx}\\right)$$ with $px=\\omega t-\\vec{p}\\cdot\\vec{x}$.", "281" ], [ "There are two problems with your derivation. The first one is in the calculation of $[\\vec S,\\vec J^2]$. In the final step, you are implicitly using $\\vec S\\times \\vec S$ which is false.", "359" ], [ "A close attention to the anticommutation rules gives: $$ \\vec S\\times\\vec S = i\\hbar\\vec S $$ so this leads to: $$ [\\vec J{}^2,\\vec S] = 2i\\hbar((\\vec S\\times \\vec J)-i\\hbar \\vec S) $$\nYou also have a second problem in the triple cross product formula. If you look closely, you are implicitly assuming that the three operators commute when you apply it.\nInstead, you'd get: $$ ((\\vec S\\times \\vec J)\\times \\vec J)k = S_lJ_kJ_l-S_kJ_lJ_l\\ = S_lJ_lJ_k+S_l i\\hbar\\epsilon{klm}J_m-S_kJ_lJ_l $$ so in vectorial notation: $$ (\\vec S\\times \\vec J)\\times \\vec J = (\\vec S\\cdot \\vec J)\\vec J+i\\hbar(\\vec S\\times \\vec J)-\\vec S\\vec J{}^2 $$ as you can see, you forgot the extra cross product term and the ordering of your second term was a bit cavalier. You can further symmetrize the third, final term: $$ \\vec S\\vec J{}^2 = \\frac{1}{2}(\\vec S\\vec J{}^2+\\vec J{}^2\\vec S-[\\vec J{}^2,\\vec S])\\ =\\frac{1}{2}(\\vec S\\vec J{}^2+\\vec J{}^2\\vec S)-\\frac{1}{2} [\\vec J{}^2,\\vec S] $$ to get: $$ (\\vec S\\times \\vec J)\\times \\vec J = (\\vec S\\cdot \\vec J)\\vec J+i\\hbar(\\vec S\\times \\vec J)-\\frac{1}{2}(\\vec S\\vec J{}^2+\\vec J{}^2\\vec S)+\\frac{1}{2} [\\vec J{}^2,\\vec S] $$\nIncorporating these modifications, you'd rather get: $$ [\\vec J{}^2,[\\vec J{}^2,\\vec S]] = 2i\\hbar[\\vec J{}^2,(\\vec S\\times \\vec J)-i\\hbar \\vec S)]\\ = 2i\\hbar([\\vec J{}^2,\\vec S]\\times \\vec J+\\vec S\\times[\\vec J{}^2,\\vec J]-i\\hbar[\\vec J{}^2,\\vec S])\\ = -4\\hbar^2(((\\vec S\\times \\vec J)-i\\hbar \\vec S)\\times \\vec J-\\frac{1}{2}[\\vec J{}^2,\\vec S])\\ = -4\\hbar^2((\\vec S\\cdot \\vec J)\\vec J+i\\hbar(\\vec S\\times \\vec J)-\\frac{1}{2}(\\vec S\\vec J{}^2+\\vec J{}^2\\vec S)+\\frac{1}{2} [\\vec J{}^2,\\vec S]-i\\hbar(\\vec S\\times \\vec J)-\\frac{1}{2}[\\vec J{}^2,\\vec S])\\ = -4\\hbar^2((\\vec S\\cdot \\vec J)\\vec J-\\frac{1}{2}(\\vec S\\vec J{}^2+\\vec J{}^2\\vec S)) $$ which is the advertised form, with $\\alpha = -4\\hbar^2$ (which has the correct dimensions).\nHope this helps and tell me if something's not clear.", "532" ], [ "Superconducting Wavefunction Phase (Feynman Lectures)\nIn Volume 3, Section 21-5 of the <PERSON> lectures (superconductivity), <PERSON> makes a step that I can't quite follow. To start, he writes the wavefunction of the ground state in the following form (21.17):\n$\\psi(r)=\\rho(r)e^{i\\theta(r)}$\nIf the density $\\rho^2$ is approximated to be constant throughout a superconducting block, then <PERSON> says (21.18) that the (probability) current density can be written $J=\\frac{\\hbar}{m}\\left( \\nabla\\theta-\\frac{q}{\\hbar}A \\right)\\rho$\nBy insisting that the divergence of the current be zero, <PERSON> shows that the Laplacian of the phase is zero. (Assuming $A$ is chosen to have zero divergence).\n$\\nabla^2 \\theta =0$\nI follow everything up to here.\nThen he states that, for a single lump of superconducting material (by which I assume he means finite and simply-connected) this implies $\\theta=0$.\nI don't understand that step...I recognize that the <PERSON> equation has $\\theta=0$ as its unique solution if the boundary conditions are $\\theta=0$. But the implied boundary condition for the superconducting chunk I would assume is only $J=0$ normal to the boundary (so no current flows in/out), which is not equivalent to $\\theta=0$.\nNow, for concreteness, let me choose a B-field $B=B_0\\hat{z}$. Then one choice of $A$ is $A=B_0x\\hat{y}$.", "474" ], [ "This choice makes $\\nabla\\cdot A=0$. In fact, if we use this B-field, then we can set $\\nabla\\theta=\\frac{qB_0x}{\\hbar}\\hat{y}$, so that $J=0$ everywhere. The divergence of $\\nabla \\theta$ is zero, so <PERSON>'s equation is satisfied, and we can integrate this up to get a wavefunction\n$\\psi(r)=\\rho e^{i qB_0xy/\\hbar}$\nSo what have I done wrong? Why does <PERSON> say $\\theta=0$? This seems important as the next step results in the a London equation. [EDIT: <PERSON>, below, pointed out that this example was not valid. The reason is that my choice of $\\nabla\\theta$ has curl, and thus is not a possible gradient. Furthermore, my answer below lists an alternate route of derivation from <PERSON>'s.]\nThanks!", "474" ], [ "Radiation field of a scattering experiment moves faster than light\nConsider an electron with 4-momentum $p$ which receives a sudden \"kick\" at $t=0$. After the collision, it has momentum $p^\\prime$. Now I am interested in the radiation, that the particle is emitting. According to <PERSON> and <PERSON>, this field is: \\begin{equation} A_\\rho(x) = \\text{Re} \\int \\frac{d^3k}{(2\\pi)^3} \\; e^{-ik\\cdot x} \\frac{-e}{\\left|\\mathbf{k} \\right|} \\left(\\frac{p^\\prime_\\rho}{k \\cdot p^\\prime}- \\frac{p_\\rho}{k \\cdot p} \\right) \\end{equation} Where $k^0 = \\left|\\mathbf{k}\\right|$ is implicit. I was interested in the potential in real space, so I wanted to evaluate the integral. Using spherical coordinates I obtained: \\begin{equation} A_\\rho(x) = \\int_0^\\infty d\\left|\\mathbf{k}\\right| \\int_{-1}^1 d\\cos \\theta \\int_0^{2\\pi} d\\phi \\; \\cos \\left(-\\left|\\mathbf{k}\\right| t +\\left| \\mathbf{k}\\right| \\left|\\mathbf{x}\\right| \\cos \\theta \\right) \\left[... \\right] \\end{equation} Where the expression in the brackets does not depend on $\\left|\\mathbf{k} \\right|$.", "402" ], [ "Since the integrand is symmetric in $\\left|\\mathbf{k}\\right|$, the corresponding integral can be evaluated from $-\\infty$ to $\\infty$ as well, if an additional factor $1/2$ is multiplied. Then the $\\left|\\mathbf{k}\\right|$-integration should yield a delta distribution $\\delta (-t + \\left| \\mathbf{x} \\right| \\cos \\theta)$. But this implies, that the solution is only non-zero, if $\\left|\\mathbf{x}\\right| > t$, i.e. the solution is outside the lightcone. Hence the field travelled faster than light or the field appears instantanous at $t=0$ in the entire space.\nHow can I make sense of this? Where did I make a mistake?\nThe integral can be analyzed further: Let $\\mathbf{x} = \\left|\\mathbf{x}\\right| e_z$ and $\\mathbf{k} = \\left| \\mathbf{k} \\right| (\\sin \\theta \\cos \\phi, \\sin \\theta \\sin \\phi, \\cos \\theta)$ and $\\mathbf{p} = \\left| \\mathbf{p} \\right| (\\sin \\theta_p \\cos \\phi_p, \\sin \\theta_p \\sin \\phi_p, \\cos \\theta_p)$. Then the integral becomes (essentially): \\begin{equation} A_\\rho (x) = \\text{Re} \\int_{-\\infty}^\\infty d \\left|\\mathbf{k}\\right| \\int_{-1}^1 d\\cos \\theta \\int_0^{2\\pi} d\\phi \\frac{e^{-i\\left|\\mathbf{k}\\right| (x^0 - \\left|\\mathbf{x}\\right| \\cos \\theta)}}{p^0 - \\left| \\mathbf{p} \\right| (\\sin \\theta \\sin \\theta_p \\cos\\phi - \\phi_p + \\cos \\theta \\cos\\theta_p)} \\end{equation}\nAs mentioned, the $\\left|\\mathbf{k}\\right|$ integration yields a delta distribution. Then $\\cos \\theta$ integration can be executed.", "402" ] ]

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[ [ "So the paper's\n* \"Numerical infinities and infinitesimals: Methodology, applications, and repercussions on two <PERSON> problems\", <PERSON> (2017),\nand it's basically a discussion on the author's \"grossone\" approach that they've been pushing for quite a while now (at least since 2004).\nThe tl;dr on it is that they're proposing a slightly abstracted data type, kinda like how complex number data types generalize real number data types, except this one's focused on infinities instead of imaginaries.\nThe author seems to want CPU's to include support for grossone's in their arithmetic logic units (ALU's), e.g. as specified in their patent. The author's website and publications seem to focus on applied use in mathematical optimization; they seem to justify their work in terms of theoretical work as an afterthought.\nSome of the harshest criticism seems to come from folks who're knocking it as-though the author were trying to report their work as some new theory, arguing that it's weaker and less sophisticated than prior work, e.g. hyperreal numbers.", "484" ], [ "The weird part about this is that, as far as I can tell, that's what the author wanted to do; they're trying to make an abstract data type to replace floating-point data types for common calculation units, not solve the mysteries of the universe.\nIn general, I'd expect folks who get the author's intent to receive it with a bit of a yawn. The arguments for modifying mainstream ALU's don't seem too compelling, and at-current there's likely not much demand for custom CPU's that implement it.\nThe author appears to have implemented grossone's at a software level, kinda like how computers do complex-number operations. Since they're using a non-primitive numeric data type, their calculations'll be slower for it; but if they distribute the library and can demonstrate how it's worth the performance hit in some useful applications, some folks might start using it in those cases.\nIn short, it looks like the controversial proposal's for an abstract data type that includes infinities for use in common calculations. It looks like applied work rather than theoretical, a misunderstanding which seems to have ruffled some feathers; however, at the end of the day if the authors can show that it's useful in real-life coding scenarios and make it available, then folks might use it.", "77" ], [ "All right, so let's say you have this spacefaring race. They've been expanding, getting themselves into new environments, and having babies on completely new planets. The only problem is that some of these babies don't develop too well in these new environments; some are stillborn, some deformed, and some are just straight up missing things. One of these things is the Parthen version of a uterus.\nFor the latter deformed babies, the future looks pretty grim; without the possibility of bearing children, they'll look to other ways of attaining lasting happiness and satisfaction. Some may become doctors and biologists, and in their hi-tech world, they may seek answers as to how to solve their infertility.\nFinally, after decades of research, a solution is devised: they can't repair the uterus, and it's too late to clone and insert a new one, but what they can do is hijack the uterus of a surrogate mother, splicing DNA from both parties to create a hybrid baby.", "1008" ], [ "And since the baby is getting genetic material from both mothers, it's got a fifty-fifty chance of having the same deformity, and needing to use the same process to have its own children.\nI think you said somewhere that some of your Parthans already couldn't reproduce on their own; this solution could work for them too.\nWhat I'm imagining is some sort of cyborg-genitals (never thought I'd say that), but given an advanced enough species I guess it's possible that they could just use some other parts of Parthan anatomy to get the job done. Perhaps the baby would get all of the 'father' DNA, instead of a split; that would make more sense to me, but may not work in your story. Also, with more of a biological solution, there could be more drastic physical changes due to hormones, leading to a more 'masculine' appearance (rather than a woman with a baby-making attachment strapped on).\nAfter a while, this solution might not be the best one (that is, the original problem may have been solved in a more satisfactory fashion), but by then there would be enough 'men' around to sustain a viable population. Plus, by then the Parthans might have found more uses for them, such as the ones other answerers have mentioned.\nWhat I'd like to stress with this answer is that it sounds quick and dirty, but that's exactly why it makes sense: people will go to great lengths to ensure the survival of their genes. The solution may not be the best, but given the direness of the problem, some concessions can be made.", "1008" ], [ "tl;dr- Provide your human contact with as many bits of one-time pad cipher as they need. This results in perfect message secrecy; other humans won't ever be able to break it, even with hyper-advanced quantum computers.\nProvide one-time pads\nEncryption via a one-time pad is perfect and unbreakable, as long as:\n1. the one-time pad was generated using a process that attackers can't reverse-engineer; and\n2. each part of the one-time pad is discarded after use, never to be reused.\nHumans have plenty of methods for generating high-quality informational entropy, i.e. one-time pads that can't be reverse-engineered. But, as an alien AI, you probably have crazy patterns and methods that we couldn't begin to hope to reverse-engineer, meaning that you're an excellent source of extreme-quality entropy.\nDon't use normal encryption methods\nThe best encryption methods are pretty much unbreakable, we think, as far as modern human knowledge and technology go.", "242" ], [ "But why bother? You can use perfect encryption via one-time pads.\nAdd junk data if you want\nThe one big information leak from one-time pad communication is the amount of information and time it was transmitted. This is, if someone sends you a message that's 100-bytes long, then spies can know that you received a 100-byte message. They wouldn't know what it says, but since they know it was sent, that's still technically an information leak.\nSo, add junk data to fill out messages up to some certain size, let's say 100TB. Then, all a spy knows is that a message was sent that was up to 100TB in size.\nThis would be impractical for humans, since getting 100TB of high-quality single-use entropy for each message would be really annoying and costly, but since you're an alien AI, it's probably basically free for you.\nSchedule regular transmissions\nHave your human contact send messages at regularly scheduled times, even if they've got nothing to say and just end up sending pure junk data.\nThis way, no one knows when you're actually sending messages. All any spy can tell is that they're not sending you more than the message size at the regularly scheduled rate.\nUse a hidden transmission channel\nUsing the above tactics, no spy could ever read your communications or know when you're sending them. At most, they know that you're not sending more than, say, 100TB of messages every communication cycle; which, since that's already pretty much a given, doesn't matter.\nBut, if you want to go one step further, you could do a directional transmission channel. This would have the advantage of spies not even having the chance to realize that there is some sort of secret communication going on.", "209" ], [ "tl;dr- We don't actually believe that the laws of physics are perfectly accurate, precise, or immutable. Instead, we tend to work from the observation that the universe seems consistent with certain models as far as we can tell.\nWe haven't gotten to explore distant galaxies yet. And given that the observable universe isn't 200-billion light-years wide – it's less than half that in diameter – we really don't have much to work from.\nExample: We don't believe that the speed of light is constant\nFor an extreme example, we often say that the speed of light, $c,$ is a constant – however, scientists don't believe it in an absolute sense. What we actually believe is that the speed of light seems consistent with a constant so far as we have been able to tell.\nIf we did take the speed of light being constant to be literally and absolutely true, it'd imply stuff about how smooth spacetime must be and answer structural questions about scales at-and-below the Planck length. Unfortunately, science isn't that easy; 'til we can meaningfully test how fast light moves between two points ${10}^{-100}\\,\\mathrm{m}$ apart, if such a test is even physically sensible, we can't claim light to move at a constant rate at that scale.\nThe speed of light is an extreme example since its constancy is such a cornerstone of modern physics. The point's that we don't generally assume even the most cherished scientific assertions to be absolute; it's all about accepting the apparent consistency of an explanation in its correspondence to observation until we have a new explanation that corresponds better, applies more widely, is easier to work with, or/and has some other merit that makes it worthwhile.\nWe don't believe the laws of physics are the same in other galaxies\nWe don't believe that the known laws of physics behave exactly the same way in other galaxies. Instead, what we've got are a bunch of models that seem to work better than any known alternative in the contexts in which we've tried to develop them.", "781" ], [ "So if we must speculate about how things work in a far-flung context, the best we can really do is tentatively extrapolate until experimental verification can provide us with more insight.\nSo, maybe the fine-structure constant, $\\alpha$ varies over the universe; perhaps we'd one day describe some sort of universe-scale physics that causes it to vary. But, 'til we have some mechanism to describe it, what can we really do?\nHistorical analog: Atomic physics\nIn the early 1900's, scientists were working with trying to model the atom. Their early attempts were largely based in the physics that they already knew from human-scale physics, e.g. the <PERSON> model and <PERSON> model for atoms. They basically tried to force observations into the framework that they already knew, then relaxed the framework as that didn't quite work.\nExploration of the distant universe may work out similarly. This is, we'd likely try to fit everything into the models that we've got, then relax them as necessary to capture observations that we can't make fit into existing models.\nOf course, this doesn't mean that we believe or disbelieve in our current models applying. It's just that, until we have cause to suspect otherwise, we tend to suspect that our current models are more likely to be useful than models that we have no reason to suspect to be useful, e.g. random speculation.", "484" ], [ "Another possibility, somewhere between API and new language: create a domain-specific language on top of a general-purpose language. Think regular expressions: a mini-language, with its own syntax, built for just one purpose (e.g. text processing), which is usable from within another, more flexible language. Then you get the benefits of a language with a close fit to the domain, but also get a full language that you don't have to implement yourself if things start to get complex.\nLisp, Scala, and Ruby are popular choices for DSLs. Because they're so flexible, you can build a DSL directly inside the host language; this is called an embedded DSL. Interesting examples are Clojure's core.match and Midje, Ruby's rspec unit test library, and Scala's Baysick, a DSL that strongly resembles classic BASIC created using just Scala's own facilities.", "904" ], [ "The designs behind embedded DSLs differ by language; in Clojure and other Lisps, they usually use a lot of macros, while Scala gets a ton of mileage from implicits and Ruby gets a lot of use from blocks. Scala's and Ruby's flexible policies on using parentheses around function arguments are also a big help.\nYou can also create an external DSL by writing a simple parser and a small interpreter. You can use the parser generator libraries that others have suggested, but if the language is simple enough, you don't actually need to create an abstract syntax tree or a symbol table; you can just parse and execute commands one at a time, possibly holding on to some state as you go. If your syntax is constrained enough, you can just tokenize a line with regular expressions, then loop over the tokens. If there are no user-defined commands, you can just have a class or function for each command; you can store them in a table, and use the command name at the front of each line to look up the appropriate command and pass it arguments. The commands can validate that they received the appropriate type and number of arguments.\nIf you want to take the external DSL approach, you might be interested in the Interpreter Pattern as a way to organize things.", "904" ], [ "The project is far too big for him to do himself. So he needs to automate. If he doesn't start out with the knowledge needed to try the right things, he's going to be stuck; doing research takes an incredibly long time, and he'd need to recreate hundreds of years of work of millions of people.\nBut let's assume he knows the basics of how semiconductors work, and so on. Very soon he's going to need to build some. But for that he'll need precise machining. So he'd better start by building some machine tools. That's tough to do without regular tools, so he'd better start with metallurgy and so on.\nSo, he starts with tools and uses them to build machine tools (lathes, etc.) and so on. He might spend thousands of years perfecting the designs to be quick to make with the ore he can dig and burn on his own, so that he can replace parts much faster than the things wear out. (He'd also probably end up favoring more difficult-to-work-with alloys of steel that have superior corrosion resistance just because the ratio of time-to-corrode to time-being-used would be a lot higher than for a normal machine, once his time was spent on other things.)\nThen he has to get some sort of really basic semiconductor fabrication facility, and some sort of electricity generation. Hydroelectric power is almost stupidly easy to use: you need some decent wire to wrap around things, and a few permanent magnets would help, and you're off to a start.\nSo, he's got metal and electricity and knows how to make motors. That's good, because now he can start with dumb automation of things: doors that open and so on. He might not need to bother with batteries yet; he can't walk that far anyway, so just leave power cords everywhere.", "159" ], [ "Normally we'd use plastic to insulate them, but wax paper is far easier to make (or segmented clay wrappers).\nNow that he has gotten to this point, if he's managed to remember any physics (I hope he wrote it all down!) he'll hopefully recall how to build a lot of common simple tools for use with electronics: voltmeters and so on. And he'll remember how to grind lenses (pretty simple, actually), and so on. Eventually he'll have a decent set of pretty basic analytical equipment, just enough to get started on semiconductors.\nHe really, really wants semiconductors, because, made robustly, they can last practically forever.\nThis would be the hardest part, though: you need to do chemistry to get the right doping agents, you need to have things clean to get good silicon crystal growth, and so on. There might be easier ways, but we haven't really found them. If he put all his effort into making simple circuits that would help him automate things he was doing by hand, he might just be able to bootstrap to the point where he could generate enough computational capacity to do something interesting: having machines designed to build machines that build those same machines and produce semiconductor facilities and so on.\nOnce you get to the point where you can automatically keep this process going, the man could focus his attention on each area that needs improvement. I'm not sure how many thousands or millions of years it would take one person with largely automatic factories to figure out enough materials science to make components enough tougher so he wasn't spending all his time fixing critical things that broke. Or to figure out programming languages in which he could implement enough artificial intelligence to get the machines to start e.g. selecting sites for mining, instead of him finding them and setting them up.\nBut eventually, maybe, he would. And then he sort of would be a god, a god of simplistic autonomous machines that would do his bidding to extract resources and eventually put them towards building a spaceship. That would, in all likelihood, not be the hard part, at least if he has time. He's got a whole planet full of resources (and robots) and as much time as he needs to set off rocket after rocket until he works it all out, and if he needs to spend a thousand years to send enough stuff into orbit to sustain him on a journey to another star, who's counting?\n(I think 500 years is a serious underestimate, though; I'd expect tens of thousands.)\nSo, one person with just their own hands and no tools can't reasonably do it. But with machines, they quite possibly can, and one can build machines with one's own hands.", "159" ], [ "Let's consider what issues we'll need to overcome if we want the singularity to happen.\n1. We need to develop a general-purpose AI.\nExisting AIs are trained to solve specific problems, and would be entirely useless outside of those domains. Most current AI research isn't even trying to do this. Rather, we develop models that can effectively make predictions/decisions for the task at hand, and train it with data specific to the task.\nDeveloping models makes heavy use of domain-knowledge; even if you have a fixed task and a fixed set of features, the quality of a model can be massively affected by changing the representation of those features. The structure of the model itself will also depend on what sort of relation we want to model: e.g. does the prediction depend on only the most recently observed features, or does it care about which ones were observed previously? Are there cases where the prediction should depend on global tendencies in the input? Cases where the input has an implicit internal structure that must be modeled? Cases where some features in the sequence matter more than others? In my own area of research (natural language processing), the answer to all of those is yes, and failing to take those into account will make for a worse model.\nYou could train the best model in the world for a given task, change the input representation slightly, and the model would be completely worthless. It would eventually become useful again if you continued training on the new format, but it would basically be retraining from scratch (and from a poor starting position, too; it would need to unlearn what it had learned before it could make any real progress). If you tried to take a model from one domain and use it in another domain entirely, e.g. taking a machine translation system and trying to use it to control a self-driving car, you would definitely need to retrain from scratch to get any results, and the structure of the model would be all wrong, so you'd probably get terrible results even then.\n2. It needs to be able to design other AIs\nThis may seem like it follows from the first part, but it doesn't. Even if it possesses generalizable problem solving abilities, that doesn't mean that it can do everything. Case in point, humans are general-purpose intelligences, and most of them don't know how to design AIs.\nBeing self-improving isn't enough. All AIs are self improving; that's what training is all about.", "64" ], [ "If you give any model new training data, and let it train for longer (and avoid overfitting and various other issues that I'm glossing over for the sake of brevity), any AI will improve. Eventually.\nBut for every model, there's a theoretical limit to how well it can model the process we're interested in. If we want the kind of unbounded exponential growth that the singularity people talk about, our AI needs to be able to design new models, not just tune the existing ones. Which means it needs domain expertise on designing AIs. The good news is, the people designing the AIs possess that knowledge pretty much by definition. The bad news is, that doesn't mean we can explain it well enough to program that knowledge into an AI: there are a lot of things where we just develop an intuition for what sort of things work, through experience. There are plenty of things we do understand well enough to explain, but the frontiers of research are always something of a black art.\nMost of these issues are practical, rather than theoretical, and given enough time, data, and hardware, you could probably have a general-purpose AI figure out the domain knowledge on its own.\n3. The improvement must be unbounded by physical limitations (for awhile, at least)\nMaking an AI that's twice as powerful as the previous one doesn't help if it uses so many resources that it's running at half the speed. AIs are resource-intensive; even the single-domain ones we have now can make full use of just about any hardware we throw at them, up to and including supercomputers. You can certainly make a lot of progress by designing better, more efficient models that run on the current hardware, but eventually you'll need to stop and wait for better machines to be designed and built. And even then, we eventually run up against physical limits: information is limited by light speed delay, and component density is limited by the Schwarzschild radius of the processor, if nothing else (presumably other hard limits would kick in earlier; consult your local physicist for details). Maybe the AIs get good enough before we run into any fundamental limits, maybe not. But the fact that we need to stop and build physical machines at any step of the process means we don't get to stay on the exponential improvement curve; the best case scenario is that the time to develop a new AI goes to 0 and the construction time becomes the dominant factor.", "64" ], [ "The ability to deliver energy relatively quickly is basically the distinction between a \"capacitor\" and a \"rechargeable battery\". This isn't a physics factoid so much as just what the words mean.\nFor example, in the below plot:\n$ {\\require{color}} {\\definecolor{capacitor}{RGB}{255,10,10}} {\\definecolor{lightCapacitor}{RGB}{255,131,131}} {\\definecolor{battery}{RGB}{186,138,20}} {\\definecolor{lightBattery}{RGB}{219,194,133}} % %\\text{For example, in the below plot:} \\ \\hskip{1em} \\lower{2.5ex}{ \\begin{array}{l} {\\rlap{\\color{capacitor}{\\rule{15px}{15px}}}} {\\rlap{\\raise{4px}{\\hskip{4px} \\color{lightCapacitor}{\\rule{7px}{7px}}}}} \\hskip{21px} {\\raise{2px}{ {\\color{capacitor}{\\textbf{Li-ion capacitor}}} ~\\text{has a higher discharge rate; though} }} \\ {\\rlap{\\color{battery}{\\rule{15px}{15px}}}} {\\rlap{\\raise{4px}{\\hskip{4px} \\color{lightBattery}{\\rule{7px}{7px}}}}} \\hskip{21px} {\\raise{2px}{{\\color{battery}{\\textbf{Li-ion battery}}} ~\\text{can store more energy.}}} \\end{array} } $\n$\\hskip{50px}$$ {\\require{cancel}} {\\def\\place#1#2#3{\\smash{\\rlap{\\hskip{#1px}\\raise{#2px}{#3}}}}} \\place{305}{219}{\\color{capacitor}{\\bcancel{\\phantom{\\rule{97px}{25px}}}}} \\place{377}{191}{\\color{battery}{\\cancel{\\phantom{\\rule{25px}{7px}}}}} $\nNote that power has units of $\\left[\\frac{\\text{energy}}{\\text{time}}\\right]$. This is, power is the rate at which energy's delivered.\nConceptually, there seems to be a conflict-of-interest between storing energy and being able to rapidly lose it (i.e., deliver power). As shown above, particular technologies tend to have a trade-off between their ability to store and deliver energy.\nThis conflict may be seen as similar to that with thermodynamic reversibility in which slower processes tend to have higher efficiencies. For example, useful heating has the highest thermodynamic efficiencies when it flows down arbitrarily small temperature gradients, though the smaller the temperature gradient, the longer it takes for a finite amount of heat to move across it.\nIn thermodynamics, a reversible process is a process whose direction can be \"reversed\" by inducing infinitesimal changes to some property of the system via its surroundings, with no increase in entropy. Throughout the entire reversible process, the system is in thermodynamic equilibrium with its surroundings.", "374" ], [ "Since it would take an infinite amount of time for the reversible process to finish, perfectly reversible processes are impossible.\n–\"Reversible process (thermodynamics)\", Wikipedia [formatting and references omitted]\nIt's actually kinda fun to think about the information-theoretic aspects about why this is. For example, you've probably heard about how entropy is a measure of disorder; it's perhaps more properly seen as a qualification of how states in an ensemble of possible states could flow. When there're more unbound flow pathways, things can move faster; however, that also means that entropy grows, leaking useful work.\nAlso, that leaking of useful work comes out as thermal energy (heat), which can be pretty problematic when it comes to high-voltage electronics.\nAs a historical note, capacitors used to be more physical mechanisms for storing energy while batteries used to be more chemical mechanisms for storing energy (with some funny exceptions). This continues to often be true today, though that's perhaps better seen as historical happenstance than as a basic concept to keep track of. Stuff like supercapacitors and other technologies'll continue to blur the line, since there's really no reason for a well-engineered system to be limited to a single physical approach.\nAs a final note, a defibrillators could use batteries for their principal energy storage, using them to charge capacitors that could rapidly discharge. This design pattern's called transient load decoupling, where the transient load is the electrical demand of the shock and the decoupling is how the battery has less direct exposure to it.", "284" ] ]

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[ [ "I'm not sure exactly what you are trying to do but it's difficult and probably extremely dangerous.\nThe kinetic energy of an object with a mass of 5000 kg and a speed of 27000 m/s is more than a Tera Joule. That's a LOT of energy, in the same range as a low yield tactical nuclear weapon.\n27 km/s is also VERY fast. The fastest Maglev train I have been on is on Shanghai and tops out at around 430 k/h or about 120 m/s. So you want to increase the current state of the art by a factor of more than 200, and that's no small feat.\nIn fact, 27km/s is more than 1/3 of the highest speed a human made object has ever achieved and it's higher than escape velocity from earth. Typically these speed records are achieved in space using the gravity of large stellar object as a helper.\nIt's also more than 23 times the speed of sound in air. If you move an object of that size at that speed in air, you will generate the loudest sonic boom in history and you will turn the air into plasma generating enormous amounts of heat. In other words, you would have to do this in a vacuum and a really good vacuum at that.\nThat means you need to do this in a tube, which is also tricky since the object has enormous momentum: about 100 million kg m/s. That means it really wants to go straight and you have to apply a massive amount of force to steer it.\nGiven all these challenges, the levitation energy appears to be the least of your worries, but we can take a swing at it.", "947" ], [ "In theory, levitation doesn't require any energy at all: you could theoretically just do it all with permanent magnets. You only consume (or gain) energy if you move an object in the direction of the magnetic field. As long as you move perpendicular, you are neither gaining or losing energy.\nThe actual energy consumption will depend on how you create the magnetic fields in the first place and what the geometry your field has. Assuming you can plaster several square meters full of magnets with only a small gap you need a field strength or flux density of about 1 Tesla. Current Neodymium magnets are quite strong and can actually do this.\nPaving your track with permanent magnets is going to be expensive or infeasible. So you could use electromagnets. You would only have to magnetize the area of the track where there is currently a object. This will still take a sizable chunk of energy but probably a lot less than you'll need anyway to accelerate and steer the object.", "395" ], [ "You could have a look at electromagnetic induction. When the electromagnetic field through a surface surrounded by a conductor changes, this will generate an electric current which in turn generates a magnetic field that resists this change. In the case of a superconductor, the generated field will be precisely strong enough to stop the change completely.\nSince light is electromagnetic radiation, we can imagine a substance which similarly manages to partially or fully cancels out all light that passes through it by generating electromagnetic fields opposite to the waves of the light.\nsevere speculation:\nIt seems like what you'd need to achieve this is a bunch of charged particles that are able to move without resistance. A massless charged particle seems ideal here. Sadly, since it is massless, it would be unable to not move at the speed of light. If they move around in a confined space randomly, they would create an incredibly strong and chaotic electromagnetic field. Though you could just invoke quantum mechanics and claim they move in all directions at the same time (much like particles with mass at rest bounce off the higgs field in all directions at the same time) and therefor create no net electromagnetic field.", "531" ], [ "Another problem becomes simply containing these particles, and this is a big one. You'll have to use electromagnetism to keep these particles together and this will likely be just as difficult as what the particles are doing for you (canceling the light). But could possibly be more straightforward. (Maybe a rather simple, if powerful electromagnetic field would be enough to turn any particle headed out of the confined space around.)\nwhat would this achieve?\nWell, since these particles can only cancel out light within their volume, light would be able to pass through it largely unchanged. However, inside the substance all light would be entirely canceled out. which means that it would be pitch black.\nSo the way to use it is to surround your enemies with it (or just their heads) and though you will still be perfectly able to see them, all they would see is darkness.\nsome possible side effects\nThis would interact with all electromagnetic fields, including that of the earth, so if you move this substance it would generate a field to resist this change. Since this resists all change in electromagnetic fields, it is possible that brains and nerves in general stop working within this substance. I'm not sure how to solve this one without some serious handwaving.", "477" ], [ "While Sir <PERSON>'s post is a very intriguing answer, but I'm afraid it's wrong. The sun's surface is clearly in motion, but that does not necessarily result in the radiation of audible sound, even if the sun and earth where in a fluid medium (such as a air) that would allow sound transfer.\nTo explain why, we can actually apply the same line of analysis to the earths's ocean. The surface moves a lot, so sound should be radiated. However, we hear nothing unless you are really close by and have breaking waves.\nLet's run the math with rough numbers: The ocean has a surface area of about 510 million square kilometers. $150 \\cdot 10^{12} m^2$. Let's say the average wave height is 1m and the average wave frequency is 0.1 Hz (1 wave every 10 s).", "840" ], [ "If the ocean where a sherical source this would create a sound power of $5 \\cdot 10^{24} W$ and the sound pressure at 1000 km away would be 240 dB SPL. That's obviously not the case, otherwise we'd be all dead.\nSo why not? In order for sound to actually radiate, the surface must move uniformly. For every ocean wave that moves air up there is a wave nearby that moves air down and so the contributions simply cancel. Technically speaking, we need to calculate the power by integrating the normal intensity over the entire surface, the intensity has equal amounts of positive and negative components and the sum over those is zero.\nThat's the same reason why you put a loudspeaker in a box: in open air the air motion from the front of the cone and from the rear of the cone will simply cancel out, so you put it in a box to get rid of the sound from the rear.\nSo I think the real answer here is: you would hear absolutely nothing since the sound contributions from different parts of the sun's surface would cancel each other out. Sound radiation over that distance would only occur if the sun's surface moves uniformly, i.e. the whole sun expands or contracts. That does happen to some degree but only at very, very low frequencies which are inaudible and where sound radiation is a lot less efficient.", "309" ], [ "Your question basically has two parts.\nHow would something fall up?\nThere are some theories that particles could exist which are affected inversely by gravity, such that rather than being pulled toward the source of gravity, they are repelled by it. We would not normally be able to find such particles, since 1- they would never be near any normal matter, and 2- the particles could never form a large object together on their own through gravity.\nHow would a disease cause this?\nSince you have specified a disease, I assume that you intend for microbes or parasites to be the cause of the effect. So how about this: a microbe that, when it consumes matter, converts it into this type of theoretical anti-gravity matter. The matter would remain inside the human body, despite being pulled in the opposite direction by gravity.", "279" ], [ "And if the chemical properties of the matter were unchanged by the anti-gravity conversion process, then the body's biological processes would treat it like any other matter. The matter would be combined in with normal matter in your blood and cells, where gravity's effect is overcome by strong atomic forces.\nGiven that the human body is already under normal gravitic pull and does not fall apart or suffer some sort of circulatory failure, it is fair to assume that having some of the matter in your body pulled in the opposite direction with identical force would not cause your body to fall apart or die immediately.\nThe greatest danger would be a \"head rush\" - humans who hang upside down for too long can have blood accumulate in their heads, causing loss of consciousness. But in our case, we only need 50.01% of the body's matter to be converted to anti-gravity matter in order for the person to experience weightlessness similar to zero-G that begins to cause them to rise into the air.\nThe biggest obstacle here is: how would microbes do this? Changing the physical properties of matter is no small feat, one would expect a facility like the LHC to be required to carry out this process. But much of Science Fiction is playing with \"what if the rules were a little different?\" scenarios, so if we assume that a microbe can do this, then it could produce the effect you're interested in.", "279" ], [ "If you're using a traditional rocket (i.e. anything that accelerates forwards by expelling something from the ship backwards), then the rocket equation applies:\n$$M_0 = M_1 \\exp(\\Delta v/v_e)$$\n$M_0$ is your rocket's \"wet mass\", i.e. the mass of the rocket plus the propellant at the beginning of the journey\n$M_1$ is the \"dry mass\", the mass of the rocket at the end of the journey\n$v_e$ is the exhaust velocity, the speed that the propellant is expelled from the rocket\n$\\Delta v$ is the delta-v of the journey; in relativistic contexts this is the integral of proper acceleration times proper time (acceleration times time as experienced by the rocket)\nAnd $\\exp$ is the natural exponential function (e to the power of x).\nOne way to get a 10 year journey to Proxima (4.25 light-years away) is to accelerate at 1g for 0.42 years proper time (0.43 years back on Earth), coast for 9.15 years proper time (10.02 Earth years), and then decelerate for another 0.42 years proper time to arrive at the destination. (Max velocity is 40.6% of the speed of light; total time experienced by crew 9.99 years, total time according to Earth observer is 10.88 years.) You can spin for gravity during the coasting phase, just design your habitat module to be able to handle gravity from both the thrust direction and the radial direction.\nWith a fusion engine, exhaust velocities are around 10% of light speed IIRC, and the rocket equation tells you that you need...", "234" ], [ "about 5480 kg of propellant for every 1 kg of rocket and payload at the end of the journey. There's no possible way to carry such an insane amount of propellant. So you'll need to invoke some fictional engine technology.\nWith a photon rocket that can directly convert mass-energy of your fuel to an enormous planet-scorching laser (do not point your exhaust within an AU of anyone or anything you love), you would need about 1.37 kg of mass-energy convertible fuel per kg of rocket. Much more manageable.", "574" ], [ "Using mirrors, it won't be easy.\nSuppose you want to make a planet, the size of Earth habitable that is around √2 times too far away from its star to be in the habitable zone, warm enough. What you'll need to do is increase the amount of light it gets by a factor of 2. (Since the light a planet receives is inverse to the second power of it's distance from said star.\nThere are two options, have mirrors orbiting the sun closer than this planet and you'll need a total surface of Ap(rm/rp)2 where rm and rp are the distance to the star from the mirrors and planet respectively and Ap is the surface of the planet interpreted as a flat circle (diameter of the planet times pi). I don't think it would be easy (or cheap) to have those mirrors always redirecting that light at the planet though.\nA more viable solution seems to have a bunch of mirrors orbiting the planet, possibly in this configuration.", "24" ], [ "In this case the distance of the mirrors to the star would be equal of the distance between the planet and the star, so the above formula evaluates to: Am = Ap, the surface of the mirrors should equal the apparent surface of the planet . For an earth sized planet, this number is about 113 million km2. If we take circular mirrors with a diameter of 11.2 km (which gives them a surface of 100 km2, we'll need 1.13 million of them.\nIf you allow those mirrors to be essentially side by side in orbit, you need them to be about 1.13 million km away from your planet, which seems doable.\nIn order to spread the light reflected by these mirrors nicely across the globe, the mirrors would need to be slightly concave. And will obviously need to be at an angle of about 45°\nThis will of course heat the poles more than the equators (since the mirrors will always cross over the poles) and will also illuminate the night side of the planet, but I'm sure you could solve some of those issues by adjusting the shape of the mirrors.\nIf you're wondering how bright these mirrors will be, the will in total be as bright as the sun and have a total angular size equal to that of an earth sized object at a distance of 1.13 million km away. This gives it an angular size of roughly 2.7 times that of the sun, which would make it very bright, but not quite as bright as the sun, I imagine it would look like a very thin bright line in the sky.\nAll in all this seems achievable, especially if the planet isn't far out of the habitable zone, but I can imagine there might be better solutions.", "921" ], [ "Forget science articles from non serious science sources. They are misleading to say the least.\nBasic Science\nThe two attractive forces that can work from distance are electromagnetism and gravity. So if you want any tractor beam you must use one or both.\nUnfortunately neither can be directed (as far as we know) and they \"spread\" in all directions meaning you cannot select a specific object and pull it. You will affect anything in range in the same way.\nAlso gravity cannot be created (as far as we know). An electromagnetic field can be created by an electric current. So a tractor beam is most likely to be a big electromagnet.\nElectromagnet attraction doesn't work on everything.\nAlso you will need a lot of energy to create a strong enough effect.\nIn space note that your ship attracting another object will make both to move as by <PERSON>'s third law.\nFinally consider that if you need to grab something in space to your spaceship it can be a lot easier just to use some kind of \"crane\".", "947" ], [ "The means to attach to the target can be by harpoon (but can damage the target), suction (very hard in space without an atmosphere and also needs a smooth target surface) or electromagnets (needs a iron-like object and can damage/impair sensible electronics)\nThe next cool option\nMaybe a good and cool option is to use space drones. A swarm of small rocket robots can move far away from your spaceship and grab things for you. But remember it's not that easy to move a complex object like ISS without it starting to rotate and derive in funny ways.\nLaser pulling particles\nThere are some claims in that but let's read it carefully.\nThose devices work by heating one side of the particle so air in contact with that particles ascends and this movement pulls the particle (like a miniature vacuum). It don't works in space and is limited to very small targets. A bigger laser to move a big object is more likely to use enough energy to burn it.\nNote: high potency lasers work by just reducing it's pulse duration to a fraction of second. The shorter the pulse, the higher the potency using the same energy amount. This means to continuously fire a high potency laser needs a huge amount of energy", "574" ], [ "Let's make a bunch of assumptions:\n* The largest primary is about 3 times bigger than Jupiter.\n* To really be a parent, the barycenter of a parent-satellite system must be within the parent.\n* Everything has approximately the same density\n* Orbital stability will magically work itself out (this will give us an upper bound)\nLet's call the twice the distance between the barycenter of a parent satellite system and the farthest extent of that system $D_p$ then the corresponding diameter for the subsystem $D_s$\nNow if the mass of the parent is $M_p$ and the mass of all the sub satellites together sum to $M_s$ then the requirement that barycenter be inside the parent yields:\n$$\\frac{M_s}{M_P}(D_p-\\frac12D_s)<\\left(\\frac{3M_p}{4\\pi\\rho}\\right)^\\frac13$$\nNow we know that for each parent none of the satellites can pass within the roche limit of the parent (the limit would actually be farther out due to the fact that the satellite system isn't solid but this will get us an upper bound) Lets call the diameter of the satellite system $D_s$ and the diameter of the parent system $D_p$. The Roche Limit gives:\n$$\\frac12 D_p>2.4\\left(\\frac{3M_p}{4\\pi\\rho}\\right)^\\frac13+D_s$$\nIf we claim that each subsystem is proportionate to the parent system then we have:\n$$\\left(\\frac{D_s}{D_p}\\right)^3=\\frac{M_s}{M_P+M_s}$$\nNow if we're trying to maximize the ratio of satellite mass to parent mass both of these inequalities should be equalities.\nSolving the system yields:\n$$D_p \\approx 2.6 D_s$$\nWhich means each successive moon would weigh $17$ times as much as the previous one.\nNow to get from a single atom moon to something 3 times the size of Jupiter would take: $$\\frac{\\ln\\left(3\\frac{1.89813 × 10^{27} kg}{1.6726219 × 10^{-27} kg}\\right)}{\\ln(17)}=42$$\nSo a system could have a maximum of 42 layers if we stopped at planets as the primary body.", "24" ], [ "Note however, this doesn't consider orbital stability and I have no doubt that even a system with 10 layers would be unstable on the time scale of a century.\nBigger\nIf we went up larger and larger, we could eventually incorporate black holes and then relativity plays havoc with the equations. However, I think that at the extremely large end, the expansion of the universe would distort and pull apart any orbits with radii on the order of billions of light years. So if we said that was the limit, then you could nest about $85$ layers, which is a lot, but I would hardly call that infinite.", "801" ] ]

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[ [ "Solving saddle point problem having non-invertible top-left block with a PETSc nested matrix\nMy system is a symmetric FE problem with lagrange multipliers:\n$Z=\\begin{pmatrix}A & C^T \\ C & 0\\end{pmatrix}$\nThe matrix $A$ is positive semi-definite, non-invertible. The whole matrix is invertible.\nI am working on the development of a finite element software where I want to solve such problems with PETSc in parallel. At this time I would like the $Z$ matrix to be a MATNEST in which the $A$ and $C$ matrices are assembled independently.\nWith the representative simple code at the end of this message (1D laplacian with Lagrange multipliers), and using a PCFIELDSPLIT preconditioner, the solver diverges. If I artificially force the matrix $A$ to be invertible (adding the command-line option -force_invertible), then I get the right solution.\nSo, what can I do to solve such a system with a nested matrix?\nAnother question: is it possible to use direct methods (Mumps) with nested matrices in parallel?\n#include \"petscsys.h\" /* framework routines */\n#include \"petscvec.h\" /* vectors */\n#include \"petscmat.h\" /* matrices */\n#include \"petscksp.h\"\n#include <vector>\n#include <string>\n#include <iostream>\n#include <numeric>\n// Try to solve with Petsc a simple 1D laplacian problem (or a series of springs)\n// o-////-o-////-o-////-o-////-o-////-o-////-o-////-o-////-o ...\n//\n// The boundary conditions (Dirichlet) are imposed using Lagrange multipliers.\n// The system to be solved is of the form:\n//\n// Z x = y\n// --^-- -^- -^-\n// [A Ct] [u] = [b]\n// [C 0 ] [l] [d]\n//\n// A is positive semi-definite (1 eigenvalue is 0)\n// Z is indefinite invertible\nstatic char help[] = \"Saddle point problem: scalar 1D laplacian with lagrange multipliers.\\n\\n\";\nint main(int argc,char **argv)\n{\n// Initialization ------------------------------------------------ //\nMPI_Init(NULL, NULL);\nPetscErrorCode ierr;\nierr = PetscInitialize(&argc,&argv,NULL,help);CHKERRQ(ierr);\nint rank, nproc;\nMPI_Comm_rank(PETSC_COMM_WORLD, &rank);\nMPI_Comm_size(PETSC_COMM_WORLD, &nproc);\nPetscViewer viewer = PETSC_VIEWER_STDOUT_(PETSC_COMM_WORLD);\nPetscViewerPushFormat(viewer, PETSC_VIEWER_ASCII_DENSE);\nPetscBool forceInvertible=PETSC_FALSE;\nPetscOptionsGetBool(NULL,NULL, \"-force_invertible\", &forceInvertible, NULL);\n// Problem definition and dof spliting among processes ----------- //\ndouble k=1.;\nstd<IP_ADDRESS>vector<int> globalDofs={0, 1, 2, 3, 4, 5, 6, 7, 8};\nstd<IP_ADDRESS>vector<std<IP_ADDRESS>pair<int, double>> globalDirichlet={{0, 0.},\n{8, 1.}}; // first: global dof number, second: imposed value\nauto start=[&](int rank){\nint q=(globalDofs.size()-1)/nproc;\nint r=(globalDofs.size()-1)%nproc;\nreturn q*rank + std<IP_ADDRESS>min(rank, r);\n};\nstd<IP_ADDRESS>vector<int> dofs;\nfor (int i=start(rank); i<=start(rank+1); ++i) {\ndofs.push_back(globalDofs[i]);\n}\nstd<IP_ADDRESS>vector<int> isLocal(dofs.size(), 1);\nif (rank!", "935" ], [ "Solving a large non-hermitian generalised eigenvalue problem from a linear stability analysis using SLEPc\nI have a generalised matrix problem: $A x = \\lambda B x$ from a spectral method on a linear stability analysis problem. My matrix B is diagonal and positive semi-definite. A is non-hermitian and complex.\nMy problem is essentially that when using the SLEPc generalised eigenvalue solver I get the error \"zero pivot in LU factorisation\". The rest of the below is details about the problem and things I have tried so far. Thanks for the help!\nDetails of the problem\nThe matrix will be at its largest about 48000 by 48000, and I want to find the eigenvalues. The eigenvalues I am interested in are ones with the largest real part near 0+0i. Ideally, I want to be able to find them even if they are internal (i.e when there are other eigenvalues with larger positive real part in the spectrum). However, I would be happy if I could get it to work for problems where all eigenvalues have real parts < 0 apart from the eigenvalue of interest.\nAt the moment I have used the scipy linalg.eig and sparse.eigs functions. As far as I know, these use LAPACK and ARPACK respectively to do the heavy lifting. I have decided to see if I can achieve better performance through using the SLEPc library.", "768" ], [ "If this is a bad decision, let me know!\nI want to move onto using PETSc with the SLEPc eigenvalue solvers. I have been trying out SLEPc using the examples provided as part of the tutorial. Exercise 7 (http://www.grycap.upv.es/slepc/handson/handson3.html) reads matricies A and B from a file and outputs the solutions. I got this to work fine using the matrices provided. However, if I substitute a smaller sized test version of my problem (6000x6000), I get a variety of errors depending on the command line arguments I supply.\nThe main problem I have is the error: \"zero pivot in LU factorisation!\" when I use the default settings.\nI think this might be related to the fact that B contains rows of zeros, although my understanding of linear algebra is somewhat basic. Is this true?\nI have tried setting the options suggested on the petsc website, -pc_factor_shift_type NONZERO etc but all I get is an additional warning that these options were not used\nI assumed that this was a problem with the preconditioner, so I tried setting -eps_target to 0.1 and both with and without specifying -st_type sinvert and shift. Still I get the same error.\nThen I tried -st_pc_type jacobi and st_pc_type bjacobi. jacobi runs, but does not produce any eigenvalues. Block jacobi does an LU factorisation and gives me the same error again.\nThe default method is krylov-schur, so I have experimented with the -eps_type gd and -eps_type jd options. Unfortunately these seem to produce nonsense eigenvalues, which do not appear on the spectrum at all when I solve using LAPACK in scipy.\nI know my matrix problem is not singular, because I can solve it using scipy.\nDo you know of any books/guides I might need to read besides the PETSC and SLEPC manuals to understand the behaviour of all these different solvers?\nThe output from the case with no command line options is given below.\nThanks a lot for taking the time to read my first post!\nKind Regards, <PERSON>\nTerminal output from SLEPc\ntobymac:SLEPC toby$ mpiexec ./ex7 -f1 LHS-N7-M40-Re0.0-b0.1-Wi5.0-amp0.02.petsc -f2 RHS-N7-M40-Re0.0-b0.1-Wi5.0-amp0.02.petsc -eps_view\nGeneralized eigenproblem stored in file.\n[0]PETSC ERROR: --------------------- Error Message ------------------------------------ [0]PETSC ERROR: Detected zero pivot in LU factorization: see http://www.mcs.anl.gov/petsc/documentation/faq.html#ZeroPivot! [0]PETSC ERROR: Empty row in matrix: row in original ordering 2395 in permuted ordering 3600!", "768" ], [ "Cusp Library performance worse than PETSC (GMRES 200 iterations) Why?\nI wanted to compare the speeds of the GMRES implementations in the CUSP and the PETSc libraries.\nThe matrix (A) used for testing was a 3d Laplacian matrix obtained by using the 7 point stencil on a 20x20x20 grid => the matrix is of size 8000 x 8000. This is a banded matrix with 7 diagonals.\nThe RHS (b) was obtained by multiplying A by a vector of 1's. I wanted to solve Ax=b by GMRES\nFor both PETSC and CUSP I timed only the time taken for 200 iterations of the GMRES solver (ie time taken for reading in the matrix is not counted)\nOn Petsc the timings were done with PetscGetTime() and on Cusp with Cuda events.\n%--------------------------\nTimings\nPetsc (1 cpu) took 0.<PHONE_NUMBER> sec to do 200 iterations of GMRES.\nCusp took 0.1183 sec to do the same.\n%----------------------------\nAs you can see Petsc is 2.14 times faster than the Cusp library even on a single processor. The speed gap gets larger (obviously) on using more than 1 processor.\nThis experiment was done on a GTX 570 card on an Ubuntu 10.10 running CUDA 4.0 having cusp v 0.3.1 and thrust 1.6.0\nI have read this paper by one of the authors of CUSP.", "373" ], [ "However, they have not compared the performance of CUSP with Petsc in it.\nThe paper also says that the data-structure used for storing the sparse matrix matters. Accordingly they have provided several formats like DIA, ELL, HYB, COO etc. but even after I tried them all, the Cusp GMRES performance does not change and still takes 0.1183 seconds for the 200 iterations.\nHere is the (quite-short) GPU code on pastebin I used while using CUSP. I am not sure if I am using the Cusp library in an optimal manner.\nAlthough it is possible PETSc is still genuinely better than CUSP I want to know if significant speedup is possible with CUSP if used properly.\nIf more information is needed to answer this question please let me know. Thank you.", "373" ], [ "Preconditioning technique for large sparse non-hermitian matrix\nI am attempting to solve a computational acoustics problem that involves solving an underlying sparse matrix. The size of the problem varies with grid size (3D) and fill-in's obviously make direct solution impractical. Important features of the matrix are as follows:\n1. It is non-Hermitian and particularly NOT diagonally dominant.\n2. Regardless of the size of the problem, there is always one row that consists of only one element, far away from the diagonal (and a zero on the diagonal). This is part of the problem's closure condition.\nI have attempted to solve this problem using iterative techniques with preconditioning to speed up the solution. Iterative solution without preconditioning yields fairly inaccurate results (by comparison with directly computed results for a small grid).", "623" ], [ "ILU preconditioning works for coarse grids (small matrices ~ 42000 x 42000) but fails for anything over 100,000 x 100,000; keeping a low fill-in factor ends in \"Factor is exactly singular\" and large fill-in factor ends in one of the sub-matrices being singular during pivoting. I also tried enforcing the one zero diagonal element with machine epsilon before attempting ILU but it still fails.\nRelevant problem parameters are as follows:\n1. There are 8 PDE's: conservation of mass, conservation of energy, three momentum equations for interior points of computation (full staggered grid with velocity on faces and pressure, temperature & density on cell centers), and three problem specific momentum equations on certain boundaries.\n2. There are suitable closure conditions applied to the problem to obtain a full ranked system, one of which has been described above (zero diagonal row).\n3. I am using a hybrid scheme, with divergences and certain gradients being constructed by using a finite volume approach, and the rest of the operators being constructed using a finite difference approach utilizing polynomial fitting.\nIf it helps, I am using scipy sparse libraries to carry out my computations. The iterative method I am using is LGMRES, which works without any problems when provided a suitable preconditioner. Please suggest some viable preconditioning techniques for this kind of problem.\nEdit: The sparsity pattern of the matrix is as follows:", "623" ], [ "Global truncation error behavior at fixed time step\nI am trying to solve the following diffusion equation problem:\n$\\frac{\\partial f}{\\partial t}=\\frac{\\partial (D\\frac{\\partial f}{\\partial x})}{\\partial x}+S$\n$D=1+x^{2}+\\sin(x)$\n$f(x,0)=1 , f(0,t)=f(1,t)=1$\n$S $ is choosen adequately in order to have $f_{ana} = 1+\\sin(\\pi x)\\sin(\\pi t)$ as the analytical solution of the equation to be compared with the numerical one.\nThe equation was discretized using a finite difference/ Central method in space (2nd order in space) and Euler implicit in time (1st order in time).\nThe global error behavior should follow asymptotically $\\dfrac{A}{dx^{2}}+\\dfrac{B}{dt}$ with $A$ and $B$ that do not depend on $dt$ and $dx$.\nNow after implementing the resolution algorithm on Python, and constructing the error plot variation in terms of $dx$ (2nd norm and $\\infty $ norm ) for a fixed $dt$, I was expecting a behavior following $C+\\dfrac{A}{dx^{2}}$, with a \"smooth\" decrease in the convergence rate as C would become more predominant for smaller $dx$ till reaching the constant. What I got instead (and what I don't understand) is a small increase in the convergence rate, before recovering to the constant value (\"reversed bell\" behavior).\nIs it normal to have an \"acceleration\" of the convergence rate in this case ? Is it a problem related to rounding effect of the very small space error ?\nHere is the ready-to-use Python code :\nimport numpy as np\nimport matplotlib.pyplot as plt\nimport scipy as sci\nfrom scipy.sparse.linalg.dsolve import spsolve\nimport scipy.sparse as sp\nimport sympy as sym\n#Symbolic calculation\nx, t= sym.symbols('x t')\nDxx_1=1+x**2+sym.sin(x)\nfi_1=1+sym.sin(sym.pi*x)*sym.sin(sym.pi*t) #Analytical solution\nSoi_1=-sym.diff(Dxx_1*sym.diff(fi_1,x),x)+sym.diff(fi_1,t)#Source\nDxx_2=sym.lambdify((x),Dxx_1,\"numpy\")\n#Conversion from symbolic to function\nSoi=sym.lambdify((x,t),Soi_1,\"numpy\")\nfi=sym.lambdify((x,t),fi_1,\"numpy\")\n#Lists that will contain the trucation errors for plot\nErr00=[]\nErr2=[]\n#list of the number of points in the domain\nN=np.array([10,20,40,60,80,100,120,140,160,180,200,320,640])\n#Loop on Nx\nfor Nx in N:\n#Space domain definition\nlx=1.0\nox=0.0\ndx=(lx-ox)/(Nx)\nx1=np.linspace(ox+dx,lx-dx,Nx-1)#Points of the domain where f is unknown\nx2=np.linspace(ox,lx,Nx+1)#All points of the domain\n#Diffusion coefficient\nDxx=Dxx_2(x2)\n#Initialisation\nf=fi(x1,0)\n#Time grid\nt1=0.5\ndt=0.0001\nNt=int(t1/dt)\n#Implicit matrix definition - Sparse method\ndiag0= -(2*Dxx[1:-1]/(dx**2))\ndiag1= ((Dxx[2:-1]-Dxx[:-3])/(4*dx**2))+((Dxx[1:-2])/(dx**2))\ndiag_1= (-((Dxx[3:]-Dxx[1:-2])/(4*dx**2))+((Dxx[2:-1])/(dx**2)))\ndata = [-dt*np.append(diag_1,[0]),1-dt*diag0,-dt*np.", "935" ], [ "Getting started with FEM: Ill-conditioned matrix when evaluating flux terms in conservation law?\nI have a system of conservation laws of the form\n$$ \\frac{\\partial \\mathbf{q}}{\\partial t} + \\nabla \\cdot \\mathbf{F}!\\left(\\mathbf{q}\\right) = 0 $$\nI want to use finite elements to solve this system. As an initial choice, I am using Legendre polynomials $\\phi$ for my function basis. Let $j$ be a polynomial index. If I substitute the decomposition of my unknown function $\\mathbf{q}$ and the flux function $\\mathbf{F}$,\n$$ \\mathbf{q}!\\left(t, x\\right) = \\sum\\limits_j \\hat{\\mathbf{q}}_j!\\left(t\\right) \\phi_j!\\left(x\\right) $$\n$$ \\mathbf{F}!\\left(\\mathbf{q}\\right) = \\sum\\limits_j \\hat{\\mathbf{F}}!\\left(t\\right) \\phi_j!\\left(x\\right) $$\nand finally write out the weak form (given some test volume $\\Omega$ with boundary $\\partial \\Omega$)\n$$ \\sum\\limits_j \\left(\\frac{\\partial \\hat{\\mathbf{q}}j}{\\partial t} \\int\\limits\\Omega \\phi_i \\phi_j + \\hat{\\mathbf{h}}j \\oint\\limits{\\partial \\Omega} \\phi_i \\phi_j - \\hat{\\mathbf{F}}j \\cdot \\int\\limits\\Omega \\phi_j \\nabla \\phi_i\\right) = 0 $$\nHere, I replaced $\\mathbf{F} \\cdot \\hat{\\mathbf{n}} = \\mathbf{h}$.\nMy problem occurs when I actually try to evaluate the surface second and third terms inside the parentheses. Because my problem is 1-dimensional, the second term amounts to just evaluating $\\phi_i \\phi_j$ at 1 and -1 and taking the difference ($\\hat{\\mathbf{n}} = \\pm \\hat{\\mathbf{x}}$ is the outward-facing normal).", "281" ], [ "In analogy with the stiffness matrix, we could write this as a matrix $\\mathbb{B} = {b_{ij}}$. Any given element $b_{ij}$ will be either 0 or 2 because the Legendre polynomials take the value of 1 or -1 at the edges of the domain. This matrix is sparse but singular. The third term exhibits a similar problem if we try to write it as a matrix $\\mathbb{C} = {c_{ij}}$.\nThe only way I know to solve for the $\\hat{\\mathbf{F}}_j$ and $\\hat{\\mathbf{h}}_j$ coefficients is by solving a matrix equation, but all my attempts to solve them (using PETSc) converge slowly and may not even be correct. I would like to use a preconditioner, but I get errors any time I try (PCSETUP_FAILED due to SUBPC_ERROR), even though I have specified the null spaces of these matrices.\nHave I approached this problem incorrectly altogether? Or is there a common way of overcoming this challenge, in PETSc or otherwise?", "935" ], [ "1. Can we numerically detect stiffness just by applying explicit methods?\n* Suppose you have an initial value problem for some ODE on $[0,10]$. You take considerably large stepsize $\\tau=1$ and an explicit <PERSON> method, make your calculations with constant step size $\\tau$ and get these points:\nYou estimate the error and it appears to be big. Okay, then you take $\\tau=0.1$ and obtain\nThe error estimate is acceptable now. Stepsize $\\tau=0.1$ is small relatively to $[0,10]^\\star$.\nSo, is the problem stiff? The answer is NO! Small stepsize here is required to correctly reproduce the oscillations of solution.\nThe problem we've solved is $$ y'(t)=-2\\cos \\pi t,\\quad y(0)=1. $$\n* Now you take another ODE on the same interval, $\\tau=1$ and explicit <PERSON> gives you almost the same numerical solution:\nYou take $\\tau=0.1$ and now the numerical solution is\nThe error estimate now is small. Stepsize $\\tau=0.1$ is small relatively to $[0,10]^\\star$.\nIs this problem stiff? YES! We've made very much small steps to reproduce the solution which is changing very slowly. This is irrational! The magnitude of time step here is limited by the stability properties of explicit Euler.\nThis problem is\n$$ y'(t)=-2 y(t)+\\sin t/2,\\quad y(0)=1. $$\n$^\\star$ Note that the number of step sizes can be much greater if we take longer interval of integration.\nConclusion: the information about timesteps and corresponding errors is not sufficient to detect stiffness. You should also look at the obtained solution. If it varies slowly and stepsize is very small, the problem is most likely to be stiff.", "394" ], [ "If the solution oscillates rapidly and you trust your error estimation technique then this problem is not stiff.\n2. How to determine the maximum stepsize which allows to integrate stiff problem with explicit method?\nIf you use some black-box explicit solver with automatic step control then you need nothing to do: the software will take the required stepsize adaptively.\nBut suppose you want to get the solution manually with constant stepsize, or just want to estimate how many hours you should wait until your explicit method crunches the problem. Then you should know the spectrum of your Jacobi matrix. Suppose it is real and lies in $[\\Lambda,0]$ (in your example $\\Lambda=-1000$).\nThen you should calculate the real stability interval (stability domain in complex case) of your explicit method. It is not too difficult, you need just consult any textbook on this topic. In the case of explicit Euler this interval is $[-2,0]$. Now, if you want your solution not to blow-up, you should take $\\tau$ such that $\\Lambda\\tau$ lies in the stability interval, i. e. in our case $$ \\tau\\leq \\frac{2}{|\\Lambda|}. $$\nIf you want more consistency, you should take $$ \\tau\\leq \\frac{1}{|\\Lambda|}, $$ since for $1/|\\Lambda|<\\tau \\leq 2/|\\Lambda|$ your solution will most likely produce unnatural (but fading) oscillations.\nOf course such an analysis is mostly applicable for linear problems with known spectrum. For more practical problems we should rely on numerical methods of stiffness detection (see references and comments in other answers).", "915" ], [ "1D FEM for nonlinear diffusion coefficient\nI want to solve with linear finite elements the equation $$\\partial_t u = \\partial_{x}(a(u)\\partial_xu)$$ in the domain $t \\in [0,1]$ and $x \\in [-L,L]$. Here $a(u)$ is just a function of $u$.\nApplying the weak formulation with $u(t,x)=\\sum_{j} u_j(t) \\varphi_j(x)$, I obtain $$\\partial_t u_j(t) \\int_{-L}^{L}\\varphi_i(x)\\varphi_j(x)dx = - \\int_{-L}^{L} a\\Bigl( \\sum_j u_j(t) \\varphi_j(x) \\Bigr) \\Bigl( \\sum_k u_k(t) \\varphi_k^{'}(x) \\Bigr) \\varphi_{i}^{'}(x)dx$$\n* The l.h.s is no problem because it is $M \\dot{U}(t)$, where $(M){ij}=\\int{-L}^{L} \\varphi_i(x) \\varphi_j(x)dx$ and $U(t)=[u(x_1,t),\\ldots,u(x_N,t)]^{T}$\n* My big problem is on the r.h.s. I don't know how to handle that double summation so that I have a function of $U(t)$, because I obtain a tensor $B_{ijk}=\\int_{-L}^{L} \\varphi_i \\varphi_j \\varphi_k^{'}$ ( there has already been a question about this) but I can't understand how to solve this in practice on a computer.\nAs described in the linked question, I will obtain $$M \\dot{U} = (BU)U$$ but this seems just formal to me, because of that tensor.", "935" ], [ "Any help is highly appreciated\nEDIT after knl answer:\n@knl I have a question about the root-finding step:\nAfter time discretization, I have $u_n(x)$, therefore the problem is still continuous in space. From the the scalar prodcut $$ (\\delta^{-1} u_{k,n}, v) + (a(u_{k-1,n}) \\partial_x u_{k,n}, \\partial_x v) = (\\delta^{-1}u_{n-1}, v) $$ I want to find how to compute the solution by fix point iteration\nLet $A$ the usual \"stiffness matrix\" and $M$ the \"mass matrix\":\n$$\\delta^{-1} M u_k^n + a(u_{k-1}^n) A u_k^n = \\delta^{-1}M u^{n-1}$$ where $u_k^{n}$ is the coefficients vector and $k$ is the index referring to the fix-point iteration.\nTherefore, I iteratively find $u_k^n$ by solving the linear systems $$(\\delta^{-1} M + a(u_{k-1}^n) A)u_k^n = \\delta^{-1} M u^{n-1}$$\nWhat I obtain after integration up to time $t=1$ is\nwhich is slightly different from yours. I can't understand if there's an error in my code, because the fixed point iterations seem to work.\n```python import numpy as np import matplotlib.pyplot as plt\ndef stiffassembly(M):\nx = np.linspace(0,1,M+1)\ndiag = np.zeros(M-1) #x_1,...,x_M-1 (M-1)\nsubd = np.zeros(M-2)\nsupr = np.zeros(M-2)\nh = np.diff(x)\nfor i in range(1,M):\ndiag[i-1] = 1/h[i-1] +1/h[i]\nfor k in range(1,M-1):\nsupr[k-1] = -1/h[k]\nsubd[k-1] = -1/h[k]\nA = np.diag(subd,-1) + np.diag(diag,0) + np.", "935" ] ]

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[ [ "The distinction the Wikipedia article might be trying to make is between three types of algorithms:\n1. Algorithms which go over all possible solutions, choosing the optimal one.\n2. Algorithms which go over a subset of all possible solutions, chosen so that the optimal solution belongs to the subset.\n3. Algorithms which go over a subset of all possible solution, without the guarantee that the optimal solution belongs to the subset.\nThe first two types of algorithms produce the optimal solution, while the third type aims to produce a \"good\" solution rather than an optimal solution. In my opinion, the distinction between the first two kinds is not so clear cut.\nLet me start by giving simple examples for all three types of algorithms, in the context of shortest path (the example you give).\n1. Try all possible paths. This is known as brute force.\n2. Try all possible paths, keeping track of the minimum solution so far. Whenever the current path you are constructing is more expensive than the minimum solution so far, abandon it and choose another one (we imagine that the distance is computed on a segment-by-segment basis). This is called pruning.\n3.", "242" ], [ "Look at the map, consider a few paths, and choose the best one among them. This is an algorithm for a human rather than a computer.\nThese examples are rather crude, and perhaps don't paint a very accurate picture. Pruning is crucial in many situations, for example in computer chess. If you're curious, look up the A* algorithm, which is actually used for shortest path.\nDynamic programming is a technique for speeding up significantly the brute force algorithm. It is somewhat misleading, however, to think of it this way. It is an algorithmic technique for solving optimization problems. You can implement pruning in the context of dynamic programming.\nIn the case of shortest path, here is one version of dynamic programming. We compute inductively the shortest path from the starting point to any other point of significance in the map using $t$ segments. Given the data for a certain $t$, we can compute the data for $t+1$ by enumerating over the last \"hop\" in any path from the starting point to any other point. When $t$ is large enough, we will have found the shortest path from the starting point to any other point. This is much more efficient than brute force, though not as efficient as some other dynamic programming algorithms.", "242" ], [ "Sub-exponential time algorithm to compute playoff chances\nThere are 10 teams, Team A through Team J, playing in a triple round robin pool (each team plays thrice against each other team, for a total of a 27 games per team). After the round robin pool, the top 4 teams (with the highest number of wins) make playoffs (with some tie-breaking procedure that can be done in polynomial time).\nAfter some number of games, we are given the records for each team (including all head-to-head records). Assuming the remaining $g$ games have outcomes which are coin flips, we want to calculate the percentage chance each team makes playoffs.\nHere's a brute-force solution. There are $g$ remaining games, so we can consider $2^g$ binary sequences where a 0 in each position means the team earlier in the alphabet wins, and a 1 means the team later in the alphabet wins. For each sequence, we can compute which teams make playoffs.", "143" ], [ "Then, the percentage chance of making playoffs can be computed as the number of sequences in which a given team makes playoffs divided by $2^g$.\nThis obviously has exponential time complexity (in $g$). Is there a better algorithm to solve this problem - perhaps a polynomial time algorithm using dynamic programming? Is there some way to prove we can do no better than exponential time? Is it possible to show this problem is NP-hard?\nOne simplification that can be made (which unfortunately does not reduce the complexity) is that we can compute, in polynomial time, teams which are guaranteed to make or guaranteed to not make playoffs. All games between teams in either set will not affect the probabilities for teams in the middle. As $g \\to 0$, this gives a substantial practical boost to the algorithm.\nNote that 10 teams playing triple round robin are arbitrary and this problem can be generalized to $N$ teams playing a $k$-round robin. Specifically for the brute-force algorithm, it is exponential in $g$ which may not be related to $N$ or $k$. A sub-exponential algorithm should ideally be not exponential in any of ${N, k, g}$.", "180" ], [ "Is this solution to the dining philosopher's problem entirely valid?\nIn a question on Stack Overflow, the answer by <PERSON> lists the following solution to the dining philosopher's problem:\nA possible approach for avoiding deadlock without incurring starvation is to introduce the concept of altruistic philosopher, that is a philosopher which drops the fork that it holds when it realises that he can not eat because the other fork is already used.\nHaving just one altruistic philosopher is sufficient in order to avoid deadlock, and thus all other philosophers can continue being greedy and attempt to grab as many forks as possible.\nHowever, if you never change who is the altruistic philosopher during your execution, then you might end up with that guy starving himself to death. Thus, the solution is to change the altruistic philosopher infinitely often. A fair strategy is to change it in a round robin fashion each time that one philosopher acts altruistically.", "603" ], [ "In that way, no philosopher is penalised and you can actually verify that no philosopher starves under the fairness condition that the scheduler gives a chance to every philosopher to execute infinitely often.\nI was intrigued by this solution because I hadn't heard it before. However, I can find no references to it anywhere in the existing literature.\n* I did a quick check, and saw that it isn't listed on Wikipedia as a standard solution.\n* Googling 'altruistic philosopher dining' yields only one result from Google Books that does not discuss the round robin strategy and only vaguely alludes to the altruistic philosopher to talk about the perils of starvation.\n* I tried looking up altruistic philosopher on ArXiv, only to return no results.\n* <PERSON> cites a book about nuXmv, a symbolic model checker, as his source but only provides a link to his own lab slides.\nSo my question: does this naive yet seemingly remarkable solution actually work? Or are there pitfalls that have been overlooked? I find it hard to believe that, if it works, it wouldn't have at least some mention somewhere - but at the same time I can't see why it wouldn't work, as it's a fairly naive solution.\nIf it does work, can I either a) have a reference to a proof, or b) an actual proof that this solves the dining philosopher's problem? If it doesn't, same standards apply, except for the negation of a proof. :)", "603" ], [ "Proving that context-free languages are closed under an operation\nThis is a theoretical computer science question, regarding the proof of whether or not context-free languages are closed under an operation. This means basically that any context-free language which undergoes this operation would still be context-free.\nFor a language $A$ which is a subset $\\Sigma^*$, define the language $A_+$ as\n$\\qquad\\displaystyle A_+ = {xyz | y\\in \\Sigma \\wedge xz \\in A}$.\nProve that the set of context-free languages is closed under the $+$ operator.\nSo $A_+$ contains all strings that can be obtained by inserting one symbol into a string in $A$. Show that the class of context-free languages is closed under the operation $+$ (i.e., show that if $A$ is context free, then $A_+$ is also context free).\nNote that this is not a homework question. Examples of closure proofs are sparse online and in my textbook.\nFirst, let's think about the different ways to prove closure of CFLs:\n1. Constructing a \"template\" Push Down Automata that can incorporate any other Push Down Automata and add on a part to the beginning, middle, or end of the PDA and still be able to accept the language accepted by the original CFL, with the new operation on it.", "610" ], [ "Basically, if for any given PDA P, if a PDA P' can be created which accepts the language of P with the new operation (in our case, the \"+\" operator) performed on it, then that operation must be under closure.\nSolving the problem in this manner is quite simple to think about. Imagine a PDA P which accepts strings from the CFL L. In application to our problem, this would be a PDA which can successfully read in the string 'xz', where x and z are simply any string conforming to our alphabet. The PDA P' would similarly have the ability to read xz, but each state of the PDA could have an additional self loop which reads the character in the string y.\nI have selected the answer which I find to be most appropriate for this question. It simply involves using the \"tempate PDA\" strategy which I outline above; however, my construction did not achieve the goals of the new language (think about why before looking at the answer below).", "399" ], [ "Algorithms / heuristics for a distributed sorting problem\nThe setting:\n* There's a cluster of $k$ computers (= nodes). For simplicity, assume their hardware is identical.\n* The network topology can be complicated, but let's simplify and assume it's a clique with fixed bandwidth B bits/time unit between each pair of nodes.\n* Each node has its own limited amount of memory, $M$.\n* There's a multi-set of $n$ integers (of fixed width $w$ bits), and each node has some of these integers.\n* The number of elements is not uniform among the nodes.\n* There are more elements to be sorted than there are cluster machines, i.e. $k < n$, and you may assume $k \\ll n$ if you like.\n* Each node has \"scratch space\" which is at least $s$ times the average space taken up by data on a node (i.e. at least $snw/k$). So we have $\\Theta(n)$ extra space to use, but it's distributed among the nodes.\nI'm interested in algorithms for sorting the data. The desire is to minimize the overall time, with network traffic taking up time according to the stated bandwidth.\nNotes:\n* I haven't defined exactly what each node can do in a given time unit, and that's intentional. Assume the nodes are abstract RAM machines with one operation per time unit, or choose a different model if you like.", "835" ], [ "The real life motivation involves actual full-fledged physical computers in a cluster.\n* It does not matter which node in the cluster ends up with which elements, provided that the nodes' elements can be concatenated to form a sorted sequence (and each node holds the positions of the elements it holds in this concatenation).\n* It's useful, though not necessary, for each node to know which other node ends up with which elements.\n* Randomized algorithms are acceptable, but only Las Vegas rather than Monte Carlo, i.e. the result must always be correct.\n* Assume there are no node faults and no communication faults.\n* Node clocks are sort-of-synchronized, but the algorithm shouldn't do anything funny and cute using perfect synchronization.\n* A node does not and cannot have more than $n_\\text{node-max}$ elements - both before and after the sort. i.e. the element distribution skew is bounded.\n* Algorithms in which the inter-node activity parallelizes well are desirable.\n* Important: I'm interested two variants of the sorting:\n1. Data becomes sorted among the nodes, but not necessarily within the nodes, i.e. for the appropriate order of nodes and for $x \\neq y$ in nodes $v_i$ and $v_j$ respectively - $x < y$ implies $i \\leq j$ (but weak inequality doesn't apply, because two consecutive nodes can have identical values).\n(obviously, if we reach this state, the rest of the data can be sorted in $\\tilde{O}(M/sw)$ by each node performing its own local sort.)\n2. Data becomes completely sorted - within and between nodes.\nFinally, if there are similar, related problems you know of but not a solution to mine, leave a comment or speculate in an answer on how they might be adapted.", "242" ], [ "That's not how non-determinism works, though perhaps it's how you'd simulate it in real life. Here are several ways of thinking about non-determinism.\nThe genie. Whenever the machine has a choice, a genie tells it which way to go. If the input is in the language, then the genie can direct the machine in such a way that it eventually accepts. Conversely, if the input is not in the language, whatever the genie tells the machine to do, it will always reject.\nHints. The machine computes a bivariate function. The first input is a word $w$, and the second input is a \"hint\" $x$. Whenever the machine faces a non-deterministic choice, it consults the next hint symbol, and operates accordingly.", "125" ], [ "We are promised the following:\n* Completeness: if $w \\in L$ then there is some hint $x$ which causes the machine to accept.\n* Soundness: if $w \\notin L$ then the machine rejects on all hints.\nAccepting computations. An accepting computation is a legal computation (one in which the machine always operates according to one of the choices it is faced with) which ends at an accepting state. A word is in the language iff it has an accepting computation.\nWe can formalize the notion of accepting computation using snapshots. A snapshot is a triple $(q,z,t)$, where $q$ is the current state, $z$ is the part of the word which remains to be read, and $t$ is the contents of the stack. We can define a relation $(q_1,z_1,t_1) \\vdash (q_2,z_2,t_2)$ which expresses that the machine can reach snapshot $(q_2,z_2,t_2)$ from snapshot $(q_1,z_1,t_1)$ in one step. An accepting computation for a word $w$ (for the acceptance condition of emptying the stack) is a sequence $\\sigma_0 = (q_0,w,\\bot),\\sigma_1,\\ldots,\\sigma_N=(q,\\epsilon,\\epsilon)$, where $q_0$ is the initial state, $\\bot$ is the initial state of the stack, $q$ is an arbitrary state, $\\epsilon$ is the empty word/stack, and $\\sigma_{i-1} \\vdash \\sigma_i$ for all $i$.\nAnother equivalent description is in terms of reachability. Consider a directed graph in which vertices are snapshots and there is an edge from $\\sigma$ to $\\tau$ if $\\sigma \\vdash \\tau$. An accepting computation is a path from $(q_0,w,\\bot)$ to $(q,\\epsilon,\\epsilon)$, for any state $q$.", "399" ], [ "Is there a polynomial algorithm for optimal sorting on trees?\nThere's the classical problem of sorting numbers in a list with the restriction that you can only swap two neighbouring numbers. It's easy to see that getting an optimal number of needed swaps can be achieved by insertion sort or bubble sort.\nWe can generalize this problem by changing the underlying structure from a list to a graph. Instead of swapping neighbouring numbers in a list we would be swapping numbers connected by an edge. Formally let's have a graph G=(V, E) with V = {1, ..., N} and an assignment of values f: V -> {1, ..., N} where f is a bijection/permutation. In order to do a swap we select an edge {u, v} from E and switch f(u) with f(v).", "1005" ], [ "Our goal is to sort f (that is achieve a state when f is the identity) in the least number of swaps. My question is whether there is a (polynomial) algorithm for this.\nSince working on general graphs seems really difficult from what I've tried let's restrict ourselves to G being a tree. This should be a simpler question because each number has a clear path to its target.\nSome observations:\nWhen G is a path graph the problem is the same as sorting a list which is simple.\nWhen G is a complete graph the problem is also simple since we only need to decompose each cycle into transpositions. You can actually look at the general problem as decomposing a permutation into as few transpositions as possible with the restriction of which transpositions you are allowed to use.\nAs long as the graph is connected there's a lower bound of \"sum of all distances to targets\"/2 because each swap decreases the distance to target of at most two numbers. The upper bound is \"sum of all distances to targets\" because we can select a number that wants to be in a non-articulation vertex (or simply leaf in trees) and drag it there. Then we can forget about this vertex and reduce the problem to a smaller graph.", "1005" ], [ "I will try to address why the concepts of NDTM and NP are useful, and possibly what motivated their study.\nNDTM is one of many variants of turing mahcine. For example, the classical (deterministic) Turing machine can be equipped with multiple heads and tapes, randomness or quantum states. It can also be constrained by a limited alphabet, limited tape or pre-determined head-movements (see here).\nA TM is said to decide a language (a set of words using a pre-defined alphabet), if it can halt on any input written on the tape, and accept precisely inputs belonging to the language. A language is called decidable if any TM decides it. Similarly, a function $f$ on natural numbers is said to be computable if there exists a TM which, given an input $n$, halts with $f(n)$ written on the input tape.\nIt turns out that all of the mentioned variations of TMs (including NDTM) are equivalent in the set of functions they can compute (similarly, the languages they can decide). This holds for other, much more different models than TMs, and has led to the <PERSON>-Turing thesis, which informally hypothesizes that any \"reasonable\" model of computation is equivalent to the classical Turing machine. In this aspect, NDTMs are useful as an example of fantastical computational models that are nonetheless as strong as a classical TM, supporting the <PERSON>-Turing thesis.\nAs far as I understand (see here and here for history), <PERSON> himself did not focus on complexity classes, and so the previous reason might have been his sole motivation. However, later on it was discovered that different TM variants are not equivalent in the set of problems (languages and functions) they can solve in a certain amount of computation steps (time), bound on working-tape size (memory) and success probability. With this finer resolution, it turns out that the different models are very different, resulting in a zoo of complexity classes for problems.\nI hope this is helps show why NDTMs (and the NP complexity class) are not a definite model for the problems science could potentially solve efficiently, but just one of many variations of computational models (less realistic than random and quantum machines, for example).", "915" ], [ "There are, however, some reasons for why the specific class of nondeterministic polynomial time ($NP$) is such a popular attraction of the zoo:\n1. It is relatively easy to explain and reason about. While researchers are working on many other open problems in complexity theory, the question of whether $P\\neq NP$ requires only basic knowledge in math to understand, and the concept seems so intuitive that it invites many solution attempts from amateur researchers.\n2. Whether a problem is solvable in polynomial time in a computational model is seen as an approximate measure of practical tractability (this is <PERSON>'s thesis).\n3. Any complexity bound derived by NDTMs can be seen as a bound on verification time by classical TMs (see here for why). Since classical TMs are used as models of practical computation, this has practical implications.\n4. Many real-world important problems just happen to be not just in $NP$, but $NP$-complete. This means that if $NP$ is indeed a different complexity class than $P$, all of these important problems are not solvable in polynomial time with classical TMs.\nNote that the fourth reason is unrelated to how realistic NDTMs are as a computational models (compared to classical TMs or other variants), or to any initial motivation for the invention of the concept. NP-complete problems are just surprisingly common in real life, and the scientific interest in them mirrors that.", "915" ] ]

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[ [ "This is a negative review of a game my friends & I were really excited about. There's a lot to like about this game, but after three plays (each with the same three players), we think it's broken in ways which can't be fixed without significant changes, and we would rather play another game than test changes to this one.\nThere are a couple other reviews for this game; although they rave about the game's innovative systems, they don't really describe what those systems are. If you're considering getting this game, hopefully you'll find the information below helpful; perhaps the things which bothered us won't bother you, or they won't be problems with more or fewer than three players, or you're more willing to experiment with house rules than we are. Also, a new versionis supposed to come out this year; I don't know anything about it, but maybe it will address the problems we had.\nHow excited were we?\nTwo of us bought the rules. I spent more than I will admit to at my FLGS for dedicated dice. One of us built 20 frames for everyone's use. I wrote a doomsday clock Android app. After our first two games, one of us made laminated sheets for tracking attachments & allocated dice, and bought markers for writing on them. So, we were highly motivated to enjoy this game.\nWhy were we excited?\nIn no particular order, here are some of the things we liked.\nThe price is right.", "386" ], [ "$6 for a PDF of rules? Great! (Of course this presumes that you've already got $40 of dice and $500 of Legos sitting around, ha ha.) I've seen complaints here about the rules being black & white, or having only hand-drawings of Lego units, but I don't care about any of that. (Besides, when you're printing it out yourself, black & white line drawings of Legos are better than color photos.) And the half-height layout is perfect for tabletop play; that's the way miniatures rules should be laid out. So I was happy with the rulebook itself, and its price.\nThe rules are simple, concise, and clear, so no complaints there. I really like the writing style, too. For example, the description of the stationary flags which players will be fighting over: \"A station might be a supply, command, or observation station, it might be a crashed satellite, it might be an ammo dump, it might be a jeep with a flat tire and a load of fresh peaches. Whatever: it's something worth fighting over.\" That's cool; that's my kind of game!\nArmy construction and the core of the game: you begin by building your mechs; each mech can have 1-4 attachments, where an attachment is a weapon, or some defensive attachment like a shield or ECM pod, or some movement attachment like jump jets or spider legs. (Weapons fall into three categories, but all defensive attachments have the same game effect; all movement attachments have the same game effect; etc.)\nThese attachments add dice to the pile of dice you roll at the start of your mech's turn. Each mech rolls two dice which can be used for anything; a defensive attachment lets you roll a die which can only be used for defense; a weapon lets you roll two dice which can only be used for an attack; and so on. These dice are color-coded--defensive dice are blue, movement dice are green, etc.--so if you use the same color of Legos on your attachments, you can look at any mech on the table and see what kinds of attachments it has, and therefore how many dice it will roll on its turn.\nCleverly, these attachments are also the way damage is handled: when a mech takes a hit, you choose an attachment and break it off the mech! (When you're out of attachments, two more hits kill you; you can represent the half-dead state by tearing off your mech's head or whatever.) This is a simple, fast way to track the decrease in quality of your mechs as they take damage, and having to choose which attachment to lose is painful fun: do you want to lose your shields and get killed next turn, or lose your gun and have to gum the enemy to death? Another interesting twist is that, when your mech's guns are gone, you may actually move faster, because you get to add a special green d8 (usable only for movement) to the dice rolled for that mech.\nAnother interesting thing is the way initiative & unit activation is handled. At the start of the turn, everyone rolls a d10 for each of their mechs to determine each mech's initiative, and then each mech takes its turn one at a time in ascending initiative order.", "386" ], [ "\"But sir, it's called the `deluxe' version of the 98% lean burger because it's slathered with mayonnaise. Many people like it that way.\"\nThis review is mostly irritable bitching a comparison between the Victory Point Games (VPG) and the GMT editions of No Retreat!, plus some background information for people who aren't familiar with the game at all. For me, the VPG edition is superior, but I hope to explain why well enough to make this useful to people whose tastes differ from mine. You mayonnaise-suckin' freaks.\nTo begin with: No Retreat! is a great game, and if you haven't played it, you should. Apart from the novelty of gaming the largest military campaign in history with 20 units per side, it's fast, fun, tense, and relatively simple, with several innovative systems, and with victory conditions which reward devious & aggressive play. It has cards, but it's not card-driven; the cards just introduce uncertainty about the opponent's capabilities. And any card can be discarded to pay for rail movement, replacements, etc., so there's no such thing as a bad hand: if you draw a bunch of events you can't use, that just means you've got other options. Low unit density and low stacking limits also help keep it playable. The designer has done a great job of supporting the game on BGG, too.\nHowever, the VPG version has never been called pretty. It looks like it was printed on a color inkjet printer, and it has a cover only a game designer's mother could love. But that doesn't matter because most wargamers have been trained for decades by wargame publishers, including GMT, to disregard pretty components as the least important aspect of a game.\nOn the surface, the GMT version seems to take a great game and add great components: a mounted map, oversize counters cut with rounded corners, full-color card backs, Soviet units which are red instead of pink...", "993" ], [ "wow. Never again will people look at the map and stammer, \"well, that looks... functional...\" But once you wipe away the tears of joy, you see baffling graphic design choices, a rulebook riddled with errors, and quite a few additional rules which (for me) don't improve the game.\nLet's start with the change which bugs me the most.\nThe map\nIn the VPG version, the Axis player sits on the west edge; the Soviet player sits on the east edge; various holding boxes are on the north edge; and the turn track, VP track, and terrain effects chart are on a separate sheet which you can set above the north edge, or upside down below the south edge--whatever's most convenient. No text is upside-down for either player. (The image at right does not include the expansion map, which is included in the GMT version.)\nIn the GMT version, the rules still say that's the way you should sit... but if you actually look at the map, the charts are on the east & west edges, and they're upside down to the Soviet player... the combat results tables and rail movement boxes are rotated as if the players are supposed to sit along the north & south edges, but that puts the terrain effects chart upside-down to the Soviet player... it's like the person who laid out the map didn't actually plan to play the game on it! It doesn't make sense, and it's just not as good as the VPG layout, no matter where you sit. I don't understand what they were thinking.\n(In addition to Na Berlin!, the GMT map does have a couple more rows of hexes on the eastern edge, which seem like they could be nice--I know in I wasn't impressed with the idea of until I tried it.)\nThe cards\nEach card has an Axis event and a Soviet event, and when a card is played for its event (instead of being discarded for other purposes), the event which is used depends on which player played the card.\nOne of the ways the game models the changes in the side's capabilities over the course of the war is to make some events playable only during the first half of the game, some playable only during the second half of the game, and the rest always playable. (Again, even if an event is not playable, the card can still be used for other things.) Symbols on the cards indicate which category they fall into, and you use those symbols every turn, all game long.\nSome cards also have symbols indicating that they should be added to or removed from the deck if the game continues into 1945. You use these symbols once, in some campaign games.\nGuess which set of symbols is more prominently displayed on the GMT cards, and is visible when you fan them out.", "993" ], [ "This review is intended primarily for people who are wondering how the new Fantasy Flight version compares to their old Chessex or fan-made set, and for people who want to laugh at an old & angry man's unwillingness inability to recognize & appreciate improvements. (Apparently this is part of a series of reviews complainingthat new editions are not unqualified improvements over old ones.)\nAs the gold standard for comparison, I will use my 5th edition base set. Below, some of the things I complain about may in fact have been introduced in later Chessex editions or expansions. If I don't like something in this edition, and you point out that it's not FFG's fault, we'll just have to agree to disagree.\nComponent quality & cosmetic stuff\nThere are quite a few cosmetic changes which stand out: the miniatures, the bigger boards, the card art. Let's take a closer look in that order.\nMiniatures. Bah! (You can quote me on that.) To quote myself, cruddy components are part of the charm; they let you know the gameplay's what matters.\nThe sculpts themselves are actually pretty nice. And... all right... I guess they are easier to pick up & move around than flat cardboard counters, so in that respect, they're an improvement. Fine. And the bases have tabs on them for holding treasures, so that's neat too. (Although, after a single play, some treasure markers were visibly torn up from getting inserted into the bases.) Also, when a wizard transforms into a werewolf or whatever, the miniature pops off the base and a new one drops in, so that's pretty neat.\n(It looks like the squares are large enough, and the bases on the miniatures small enough, that you can fit all four wizards in one square on those occasions when a gang-stomping is required.", "304" ], [ "Whether they still fit when you add a couple Create Wall markers & four crack markers & two dropped treasures & a Tacks marker, I'm not sure.)\nSo, although I was prepared to dislike them, the miniatures may actually be an improvement.\nThe larger boards. As the above picture shows, the new boards are almost twice as large as the old ones. That's pretty nice. (If you made your own set, the effect is probably less significant; the new boards are 9 1/2\" wide.) One interesting thing is that, rather than being blank for shuffling, the back side of each sector is a second sector with a new, more open layout. (I believe the issue being addressed was that some initial board configurations are not \"fair,\" so the intent was to give shorter runs to enemy treasures.)\n(On that point--yes, you can often look at a starting layout and say, \"he can reach a treasure on his first turn; it's going to take me three or four turns to reach one; therefore, I'm hosed,\" but things change so quickly & easily in this game that it never seemed like a real problem to me. But, the new maps do add some variety, so that's good.)\nSome fan versions have used colored markers to indicate each wizard's home base, so that you know which base is yours even after sectors are relocated, or home bases are swapped, etc. The thousand-or-so tokens included in the FFG version are all for other things, though; instead, they color-coded the boards themselves. This means that the green wizard always uses the sector in the image above as his or her base... and at the start of the game, your color is what gets randomly determined.\nThere are enough people who are \"weird\" about their player color--including, say, individuals who may have been the sinister orange wizard in every game for the last 20 years--that the new approach is clearly an abomination, a perversion, a violation of the laws of nature so shocking & egregious that nothing more needs to be said about it.\nThe card art & graphic design. Here are a couple examples of the changes:\nYeah, they have pictures now. Let's talk about that first.\nThe card art is bad. That is, the illustrations may be fine on their own, but they add nothing to the game, and they take up space on the cards, which causes the part that matters, the text, to get cranked down to an even smaller font size. And there are cards with even more densely-packed text than that Lightning Bolt card! I'm not getting goddamn bifocals so that I can play Wiz-War, you understand?\n(For a second opinion, I turned to a select panel of art historian/Wiz-War fanatic 11-year-olds, and the unanimous verdict was, \"That's not what Powerthrust should look like!\")\nPart of the reason for the pictures on the cards seems to be so that corresponding tokens (thorn bushes, created walls, etc.", "336" ], [ "Jati\nDesigned by <PERSON>, and not quite published by 3M. Later published in Spielbox.\nNote - all pictures included in this review are from BGG or other sites. My photography skills aren't nearly this good.\nThe Game\nFirst, I suppose I should establish my authority (ha!) to write about Jati. There are 19 plays of the game recorded on BGG; I don’t record my plays, but if I did that number would nearly double, as I’ve played the game 17 times. Of course, having said that, I’m sure that at best I'm a mediocre Jati player. There’s just so few people who actually play Jati that there are no experts.\nJati is one of a very small set of games which is principally famous for its lack of availability. Oddly, as hard-to-obtain games go, Jati shows up with a reasonable frequency on ebay, appearing about once every 4-6 months. They do not go cheaply, however; most sell for around $500.\nOf course, to _play_ Jati, you don’t need to go spend $500. As <PERSON> noted back in 1965, the game can easily be played with paper and pencil. Or, if you prefer, you can search out the 1986 edition of Spielbox which printed the game. So how does one play Jati?\nWell, first you have to decide which version of the game you’re going to play. The 1965 edition, on a 10x10 board, has different rules from the 1966 edition, on a 10x9 board. A detailed comparison of the rules differences can be found . Personally, I would recommend the 1966 rules:\nRegardless of which rules you choose, however, the game itself is very easy to learn and play.", "581" ], [ "Each player has 18 colored squares, plus II and III multiplier tiles, for a total of 20. The first player plays any of their tiles on any space on the board. Turns alternate; on each subsequent turn, the active player must place one of their tiles on a space orthogonally adjacent to a tile already on the board.\nOnce all of the tiles have been placed, the game is scored. Using 1966 edition scoring, you look for all rows or columns of five or more tiles of the same color (potentially with the multiplier tiles interspersed) or diagonals of four or more tiles of the same color (likewise potentially with multipliers). Each line scores a base value (5 for a 5-length straight, 8 for a 4-length diagonal), with additional points for additional tiles (2 for a straight, 5 for a diagonal), and then any multiplier is applied. Whoever has the higher total score wins.\nReactions\nActually, before worrying about reactions, there’s a historical note worth mentioning. For some time (perhaps as long as four decades, though I’d guess at least a decade) there was a mistaken understanding that Jati was designed by <PERSON>. While reasonable evidence was given that the game was not designed by <PERSON>, it was only in 2008 that it became widely known that the designer was <PERSON>. A couple of copies have surfaced with <PERSON>’ signature, one of which included a newspaper clipping from the Minneapolis Tribune from December 5th, 1965, about <PERSON> - and Jati.\nHaving resolved the issue of the authorship of the game, how is the game? Well, it’s an abstract – there is no theme to either assist the players in learning or to interfere with the play of the game. The first thing you notice, upon playing the game, is just how little of the board is used; even on the 10x9 board, more than half of the spaces are left open. While it’s good that the game doesn’t fill the board – it keeps scoring easy, and leaves sufficient room to play through all pieces – the particular number of plays chosen consistently feels light to me. A portion of this is the result of a basic issue with this game – and many others. If, in a turn, you can only accomplish a portion of a goal, there is no guarantee that the end of the game will align with interesting moves. And, unfortunately, it’s something of a let-down when the last turn (or two, or three) offer no opportunities for scoring.\nBut at the heart of the game, Jati is – as <PERSON> noted in his previously referenced write-up – closely related to other connected-line games such as . (And, in fact, there’s a variant in the 1966 version of the game which is essentially , albeit on a far smaller board.", "581" ], [ "Yep... it's another pretty negative review of a game I really want to like. Hopefully I do such a lousy job that you decide to buy the game anyway.\nThis review is based on seven plays (total) of the first five scenarios, and from compiling the War Stories collected rules threads from all Liberty Road and Red Storm rules threads that existed at the time, and from getting in Internet slap-fights with the designer over the definition of \"hexside.\" There are 12 scenarios in the game, plus another 12 in the companion game War Stories: Red Storm(the rulebooks are nearly identical), so if you want an easy way to dismiss this review, consider that there's quite a bit of the game that I haven't seen.\nFor a solid overview of the game's systems and nice photos of the components and somewhat less enraged jibber-jabber, I recommend <PERSON>'s review.\nLinks to other games I'll compare minor bits with War Stories:\n- Band of Brothers: Screaming Eaglesand Band of Brothers: Ghost Panzer\n- Conflict of Heroes: Awakening the Bear! – Russia 1941-42and Conflict of Heroes: Storms of Steel! – Kursk 1943(I haven't played later games in the series)\n- Combat Commander: Europe(I haven't played much other than the base game)\nBoring paragraph about my emotional history with this game: caught up in Sturm Europa!/Michael <PERSON> fever, this is one of few games I've ever backed on Kickstarter; although I wasn't totally clear on what I was buying, excitement was high. Shortly after funding, there was drama where <PERSON> was off the team; I was pretty sure that money was down the drain. Then, as the rulebook drafts started getting posted, they were looking surprisingly good... really good. A year later, big beautiful games arrived. I couldn't believe it: those crazy bastards had actually pulled it off!\nThat, uhh, was the high point.\nLet's start with the stuff I love--I mean really love, the reason I'm having to wipe away tears as I write this, the reason you may begin to suspect I'm launching into angry rants on unrelated topics intentionally.\nActually, first, I suppose I should get this out of the way:\nYeah, yeah, components.\nThe components are great.", "993" ], [ "I mean great--all the cardboard bits are thick enough to make Fantasy Flight fanboys jealous; the graphic design is clear & professional, with the rulebook's margins packed with helpful diagrams; everything you need to know about terrain effects on movement & combat are printed right on the terrain pieces themselves; all the map & counter & card & rulebook art is consistent... this game looks great.\n(Except for the Wreck markers; they look like Carrion Crawlers from the old D&D Monster Manual.)\n(Full disclosure: maybe the reason I'm fine with the artistic style is that I've been spending a lot of time looking at Band of Brothers: Ghost Panzerinfantry counters, which I think I've grown to aggressively hate.)\nOh, Band of Brothers reminds me: it looks like the War Stories box isn't going to fall apart. Amazing, this... cardboard box technology. I haven't tested this yet, but I believe you could beat a home intruder to death with a full box: it's that sturdy and packed full o' wood. If you're on the fence about this game, consider the safety of your family.\nWhen applying the stickers to the blocks, you do have to do the \"which side of this block is least messed up\" thing, but having bought over 20 block games from 4 publishers, I can't remember one where that wasn't the case.\n(A minor complaint is, given all the stuff that can happen in a single turn, with various units interrupting others, and some units activating twice, it might've been nice to have a few markers to indicate stuff you need to remember for the whole turn, like which units have already taken opportunity fire.)\n(Oh, err, uhh, there's also a fair amount of errata for the cards; it took me ten years of arguments to scribble on as many cards in as I did in my first week with War Stories.)\nTo end this section on a high note, it comes with a cloth bag to draw combat chips from; that's a nice touch. (Although slightly silly, as you also need another bag or a cup for drawing damage tokens from.) And they embroidered army symbols on the bag?! Are you kidding me?\nHowever, I've been defending the \"NATO symbols & paper maps are just fine\" hill long enough that my affection can't be bought with your \"mounted mapboards\" or \"cloth draw bags\" or whatever else kids are into these days. I will say no more about the components.\n\"I just love the stuff I love!", "386" ], [ "I've been lucky to play this 3 times already since I received my copy on Friday. Here are a few thoughts:\nI'll start with my final takeaway. This is a game where the players' capabilities diverge very quickly. By contrast, in Vital's previous games, all the actions are generally the same for everyone for the duration of the game. However, in Lisboa, you immediately receive a \"clergy tile\" which modifies some action or result for you and you alone, and you can then accumulate more such bonuses--many of which are cumulative with each other--very quickly. If you hammer those bonuses, you will crush. If not, you will have slow and linear progression, which will not be enough to win. In this sense, it feels quite different from his previous games, but in a very good way. **You NEED to specialize, and use your specialization as much as possible.** This is a significant difference from the previous games.\nNext, though, is a big similarity to one of his previous games--Gallerist. This one is obvious. You want as many free actions (during other people's turns) as possible. So, take as many \"favor tiles\" as you can, and don't be shy about spending your influence.\nFinally, it is quite a heavy game.", "237" ], [ "But, re the \"complex for the sake of bring complex\" comments, I fully disagree. Once you understand the theme and think about the game mechanics for the actions they represent, they all make sense and are much easier to track. For example, the variable influence cost to visit a noble represents the number of other people you have to elbow your way past when you enter his salon.\nMy first game was 4 new players. I won that game with 108 points; second place was 100. I had no particular strategy, but i did let my starting clergy tile choice guide my actions as much as possible (I took a tile that let me \"follow\" without spending influence, and made sure I had favor tiles for all 3 nobles as often as possible).\nLast night was my third game. It was me and another guy who had played already, and two new players. This time I had a strategy in mind and better understood how the parts all fit together. I won with 124 points; second place had 87. I pursued an aggressive building strategy, thanks to a couple of treasury cards that gave me a discount when building. I eventually got to a point where I only needed a couple more rubble cubes to trigger the end game, and then took a zillion decrees. I was not shy about spending influence to follow noble actions--my influence hovered below 5 the whole game. I even spent 3 wigs to follow at one point. My final score included 36 points from decree cards (!!).", "366" ], [ "I got my first two plays of Lords of Waterdeep in a session the other night, and haven't had much chance to discuss it. Looking around, I see at least half a dozen threads where LoW is being hotly debated, and rather than get involved in all those discussions, and inevitably end up repeating myself, I've decided to write a short review so I can gather my early thoughts on the game in one place. Others with more experience have already reviewed the game, so if you want in depth analysis, rules summaries or lots of pretty pictures, I advise you to read one of those. All you'll find here are my own early impressions.\nOverview\nThe system is very clean and easy to absorb. We came up to speed very quickly, even though one of the players knew absolutely nothing about the game before we sat down to play, and I was the only one who had read all the rules. We all had a solid grasp of what we were trying to accomplish before we were half way through our first game. We wasted relatively little time looking up rules, and only had a couple of questions we wanted to look up after playing.\nI'm confident that the game will scale well. The game is designed for 2-5 players, and my experience is that 3 is often a troublesome number. That was not the case here; it worked fine with 3. The number of turns in a game is determined by the number of Agents each player receives, and that varies with how many are playing, so playing time shouldn't vary much as you add or remove players. You have opportunities to do good or harm to others, but this isn't a system that encourages long term alliances. There is a map, and players will acquire buildings to place on it, but there is no geographical adjacency factor; everybody will contend with everyone else.\nTheme\nThe box has Dungeons & Dragons prominently displayed on the cover. Players are leading named factions, have named Lords, send Agents on quests, purchase buildings which provide various advantages, play intrigue cards, etc. The Quests and Intrigue cards have flavor text, taken I presume from the D&D universe. You also hire Adventurers - wooden cubes of various colors which are supposed to represent wizards, fighters, rogues and clerics.\nAll of that sounds very thematic, but you could change the Lords to Famous Chefs, the Adventurers to Recipe Ingredients and the Quests to Menu Items, and you'd have a game about running the most successful restaurant.", "386" ], [ "You wouldn't have to change any play mechanics. If being drawn into a narrative is crucial for you, LoW is not going to ring that bell.\nWhile the theme is plastered on rather than tightly bound to player actions, that plaster is well and consistently applied. If you know who <PERSON> is, and are familiar with the Red Sashes, seeing them in the game will probably please you. I'm not a D&D player, and don't know them, but the types are familiar and I wouldn't have been as likely to play a restaurant game in the first place. Once in, I found a game that is weak in terms of narrative, but well worth playing.\nDiscWorld: Ankh-Waterdeep\nLoW reminds me somewhat of D:A-M. I found D:A-M's card text and illustrations so interesting that I followed up and have now read a couple of Discworld books. I think it's entirely possible that some Eurogamers might follow a similar course, checking out D&D related titles after playing LoW. In both games, a great deal of effort was put into art and flavor text, and that can be interesting, but neither game tells much of a story despite the thematic underpinnings. The theme isn't bound to the mechanics.\nOne interesting parallel is that in both LoW and D:A-M, the players draw a card during setup representing a powerful figure in the city portrayed, and the identity of that figure establishes the long term strategy for the player. In D:A-M there are 3 lords who have identical victory conditions, and 4 others with unique conditions. This keeps the players guessing about the motives of their opponents nicely.\nIn LoW, there are 5 different quest types, and 10 of the 11 lords receive bonus points at game's end for having completed quests for 2 of those 5 types. There is also one 1 lord (lady) with a different agenda; she provides an end game bonus for buildings held rather than quests completed. There is less mystery in the LoW assignments, but it works well, and serves the purpose of obscuring scores until the final reckoning.\nComponents\nThere are several threads in the LoW forums with ominous sounding names, possibly giving the impression that various components (cards, wooden bits, box, insert) are defective or poorly designed. I attribute this to jaded gamer syndrome. The game I received is top quality.", "755" ], [ "I played (most of) a whole 2 player game of this at the UK Board Games Expo 19, and ended up preordering it (\"August at the latest\" they said). In this post I'll go over my first impressions of it and why I felt it worth the investment; so it won't have exhaustive details of all the rules or the experience of multiple plays to draw on.\nRules: The map is a made up of hexagons. Some are outside the city, and contain raw resources, some are inside the city of Ragusa (modern-day Dubrovnik) and are more traditional \"action spaces\" (upgrade your resources, get points for things etc.), and there are also some coastal tiles, containing fish (another raw resource).\nEvery turn you build one of your little buildings on one of the vertices of these hexes (though some combinations are not allowed if you have insufficient wood/stone, two of the raw resources). You do what is indicated on the three hexes you are next to. And finally, the novel aspect of the basic rules is that most of the city spaces trigger again for everyone else who has build touching that hex. This brings a whole world of tactical options into play, which we barely explored in our 2 player game, but we got some inkling into the depth that exists in this area of the game.\nTheme: Whilst not the most immersive in terms of theme, I thought it worked pretty well. I felt that I was helping to develop and urbanise the city and the area, and one of the actions in the city involved building part of the city walls (you get bonus points for your longest segment). However I was also doing it for my own benefit. I guess we played the part of local businessmen? It wasn't really explained to me (or I just forgot).\nArtwork: I liked the artwork; it looked really professional and pretty. I'm not one to decide on the artwork but it makes a nice bonus. The city walls are a nice touch, and by the end of the game we had a nice looking board. I imagine this would be even more the case if we played for a whole game, or with more players.\nReplayability: This comes in two aspects.", "349" ], [ "Firstly, there are objective cards - all the ones I saw gave 2 points for each \"thing\" you got up to a max of 12. These things were either resources in the game, or \"luxury goods\" that you could get on ships. There are 5 ships, and when ships are bought (via a town action) they are replaced with new ones.\nPlayer count: 1-5. I'm not sure what different rules apply, but from what I saw I can easily see it working well at least 2-4 players. I appreciate games having a 5 player option too.\nSummary\nThis game looks like it has real strategic depth thanks to the re-activating hexes bringing a new dimension compared to a more traditional worker placement game. This wouldn't be enough to make me buy it, but there are two other things that struck me. One is the speed of the game. Having depth like this in game that plays in under 90 minutes (more like 40 for 2p I think) is impressive. The other is that there is little downtime (a problem in many 4-5 player games). Even if it's other player's turn, you may still have actions to do if your hexes are activated. There is a small amount of randomness, which is just the right amount for me, to keep replayability without the frustration that too much luck can bring. Finally there are several different ways of scoring points (ships, completing objectives, having certain resources in certain combinations...) which gives me more confidence that the depth I felt I could see in the game is real.", "629" ] ]

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[ [ "This is a simple solution to my question. It only deals with two models and two variables, but you could easily have lists with the names of the classifiers and the metrics you want to analyze. For my purposes, I just change the values of COI, ROI_1, and ROI_2 respectively.\nNOTE: This solution is also generalizable.", "946" ], [ "How? Just change the values of COI, ROI_1, and ROI_2 and load any chosen dataset in df = pandas.read_csv(\"FILENAME.csv, ...). If you want another visualization, just change the pyplot settings near the end.\nThe key was assigning a new DataFrame to the original DataFrame and implementing the .loc[\"SOMESTRING\"] method. It removes all the rows in the data, EXCEPT for the one specified as a parameter.\nRemember, however, to include index_col=0 when you read the file OR use some other method to set the index of the DataFrame. Without doing this, your row values will just be indexes, from 0 to MAX_INDEX.\n# Written: April 4, 2019\nimport pandas # for visualizations\nfrom matplotlib import pyplot # for visualizations\nfrom scipy.stats import ks_2samp # for 2-sample <PERSON>-Smirnov test\nimport os # for deleting CSV files\n# Functions which isolates DataFrame\ndef removeColumns(DataFrame, typeArray, stringOfInterest):\nfor i in range(0, len(typeArray)):\nif typeArray[i].find(stringOfInterest) != -1:\ncontinue\nelse:\nDataFrame.drop(typeArray[i], axis = 1, inplace = True)\n# Get the whole DataFrame\ndf = pandas.read_csv(\"ExperimentResultsCondensed.csv\", index_col=0)\ndfCopy = df\n# Specified metrics and models for comparison\nCOI = \"Area_under_PRC\"\nROI_1 = \"weka.classifiers.meta.AdaBoostM1[DecisionTable]\"\nROI_2 = \"weka.classifiers.meta.AdaBoostM1[DecisionStump]\"\n# Lists of header and row in dataFrame\n# `rows` may act strangely\nheaders = list(df.dtypes.index)\nrows = list(df.index)\n# remove irrelevant rows\ndf1 = dfCopy.loc[ROI_1]\ndf2 = dfCopy.loc[ROI_2]\n# remove irrelevant columns\nremoveColumns(df1, headers, COI)\nremoveColumns(df2, headers, COI)\n# Make CSV files\ndf1.to_csv(str(ROI_1 + \"-\" + COI + \".csv\"), index=False)\ndf2.to_csv(str(ROI_2 + \"-\" + COI) + \".csv\", index=False)\nresults = pandas.DataFrame()\n# Read CSV files\n# The CSV files can be of any netric/measure, F-measure is used as an example\nresults[ROI_1] = pandas.read_csv(str(ROI_1 + \"-\" + COI + \".csv\"), header=None).values[:, 0]\nresults[ROI_2] = pandas.read_csv(str(ROI_2 + \"-\" + COI + \".csv\"), header=None).values[:, 0]\n# <PERSON>-Smirnov test since we have Non-Gaussian, independent, distinctive variance datasets\n# Test configurations\nvalue, pvalue = ks_2samp(results[ROI_1], results[ROI_2])\n# Corresponding confidence level: 95%\nalpha = 0.05\n# Output the results\nprint('\\n')\nprint('\\033[1m' + '>>>TEST STATISTIC: ')\nprint(value)\nprint(\">>>P-VALUE: \")\nprint(pvalue)\nif pvalue > alpha:\nprint('\\t>>Samples are likely drawn from the same distributions (fail to reject H0 - NOT SIGNIFICANT)')\nelse:\nprint('\\t>>Samples are likely drawn from different distributions (reject H0 - SIGNIFICANT)')\n# Plot files\ndf1.plot.density()\npyplot.xlabel(str(COI + \" Values\"))\npyplot.ylabel(str(\"Density\"))\npyplot.title(str(COI + \" Density Distribution of \" + ROI_1))\npyplot.", "392" ], [ "# The confusion occurs due to the two different forms of statsmodels predict() method.\n# This is just a consequence of the way the statsmodels folks designed the api.\n# Both forms of the predict() method demonstrated and explained below.\nimport statsmodels.api as sm\nimport numpy as np\nimport matplotlib.pyplot as plt\n# random normal x, y with y = x + 10\nx = np.random.randn(100)\ny = x + np.random.randn(100) + 10\nfig, ax = plt.subplots(figsize=(8, 4))\nax.scatter(x, y, alpha=0.6, color='blue')\n# will add the regression line to the plot and display below.\n# Plot a linear regression line through the points in the scatter plot, above.\n# Using statsmodels.api.OLS(Y, X).fit().\n# To include a regression constant, one must use sm.add_constant() to add a column of '1s'\n# to the X matrix. Basically, this tells statsmodels to calculate a constant for the regression line.\n#\n# FYI, the sklearn.linear_model.LinearRegression model includes a fit_intercept parameter\n# and does not require the X matrix to have a column of ones.\nx_matrix = sm.add_constant(x)\nmodel = sm.OLS(y, x_matrix)\n# regression_results is an object: statsmodels.regression.linear_model.RegressionResults.\nregression_results = model.fit()\n# nice summary\n# print(regression_results.summary())\n#\n# There are two forms of the predict() method:\n# There is sm.OLS(y, x).predict(). This predict() method has no knowledge of the fitted coefficients\n# produced by model.fit(), above. This is just the way the scipy developers decided to implement\n# the linear model.\n# The fitted coefficients for the linear model are in RegressionResults and RegressionResults\n# has its own predict().\n# If you use model.predict(), you need to pass the coefficients. This form of the predict() method\n# basically calculates y = ax + b where you pass the coefficients, a and b.", "988" ], [ "This is why the error\n# occurs.\n#\n# Use RegressionResults.predict() which acts as you expect, except that you still must add\n# a column of ones to the x-values used to predict y. This is because the original model\n# was fit with a regression constant (intercept). Generally linear models are fit with an intercept\n# unless there is some problem-specific reason not to.\n#\nx_pred = np.linspace(x.min(), x.max(), 50)\n# put the X matrix in 'standard' form, i.e. with a column of ones.\nx_matrix = sm.add_constant(x_pred)\ny_pred = regression_results.predict(x_matrix)\n# Line from RegressionResults.predict() in 'black'.\nax.plot(x_pred, y_pred, color='black')\n# one more graphic to add before display below.\n# So why is model.predict() provided? The calculation for a linear model is a trivial\n# linear numpy calculation. For more complex models, this will not be the case\n# and model.predict() can be useful.\n# Here is how to use it.\ncoef = regression_results.params[1] # get the fitted model coefficients\nconst = regression_results.params[0]\n# These two lines of code produce the same results, as expected.\n# y_pred = coef * x_pred + const\ny_pred = model.predict(params=[const, coef], exog=x_matrix)\n# Line from model.predict() in 'purple' overlays the 'black' line from above.\nax.plot(x_pred, y_pred, color='purple')\nplt.show()\nplt.close()", "988" ], [ "Random forest vs. XGBoost vs. MLP Regressor for estimating claims costs\nContext\nI'm building a (toy) machine learning model estimate the cost of an insurance claim (injury related). Aim is to teach myself machine learning by doing. I have settled on three algorithms to test: Random forest, XGBoost and a multi-layer perceptron.\nData set\nThe data set has the following columns:\npython cols = [ 'AGE_RANGE', 'GENDER', 'TOTAL_PAID', 'INDUSTRY_DESCRIPTION', 'WORKER_AGE', 'NATURE_CODE', 'ACCIDENT_TYPE_CODE', 'INJURY_NATURE']\n'TOTAL_PAID' is the label ($s).", "392" ], [ "The rest are features. The majority of features are categorical:\npython categoricals = [ 'AGE_RANGE', 'GENDER', 'INDUSTRY_DESCRIPTION', 'NATURE_CODE', 'ACCIDENT_TYPE_CODE', 'INJURY_NATURE']\nCode:\nImport:\n```python import pandas as pd import numpy as np\ncols = [ 'AGE_RANGE', 'GENDER', 'TOTAL_PAID', 'INDUSTRY_DESCRIPTION', 'WORKER_AGE', 'NATURE_CODE', 'ACCIDENT_TYPE_CODE', 'INJURY_NATURE'] features = pd.read_csv('gs://longtailclaims2/filename.csv', usecols = cols, header=0, encoding='ISO-8859-1') categoricals = [ 'AGE_RANGE', 'GENDER', 'INDUSTRY_DESCRIPTION', 'NATURE_CODE', 'ACCIDENT_TYPE_CODE', 'INJURY_NATURE'] ```\nFirst I turn categorical values into 0s and 1s:\npython features2 = pd.get_dummies(features, columns = categoricals)\nThen I isolate features from labels (TOTAL_PAID):\npython labels = np.array(features['TOTAL_PAID']) features = features2.drop('TOTAL_PAID', axis = 1) feature_list = list(features.columns) feature_list_no_facts = list(features.columns)\nSpit into SK Learn training and test set:\n```python\nUsing Skicit-learn to split data into training and testing sets\nfrom sklearn.model_selection import train_test_split\nSplit the data into training and testing sets\ntrain_features, test_features, train_labels, test_labels = train_test_split(features, labels, test_size = 0.25, random_state = 42) test_features.head(5) test_features.head(5) ```\nThen I explore the data:\nprint('Training Features Shape:', train_features.shape) print('Training Labels Shape:', train_labels.shape) print('Testing Features Shape:', test_features.shape) print('Testing Labels Shape:', test_labels.shape) Output: Training Features Shape: (128304, 337) Training Labels Shape: (128304,) Testing Features Shape: (42768, 337) Testing Labels Shape: (42768,)\n1. XGBRegressor\nFirst we try training XGBoost model. I needed so push # estimates above 10,000 to get a decent accuracy (R2 > 0.94)\n```python\nImport the model we are using\nfrom xgboost import XGBRegressor from sklearn.ensemble import RandomForestRegressor from sklearn import ensemble from sklearn.metrics import mean_squared_error\nx = XGBRegressor(random_state = 44, n_jobs = 8, n_estimators = 10000, max_depth=10, verbosity = 3) x.fit(train_features, train_labels) print('xgboost train score: ', x.score(train_features, train_labels)) predictions = x.predict(test_features) print('xgboost test score: ', x.score(test_features, test_labels)) ```\nHere, train and test score: R2 ~0.94.\n2. Random Forest Regressor\nThen we try Random Forest model. After some fiddling it appears 100 estimators is enough to get a pretty good accuracy (R2 > 0.", "422" ], [ "Despite the downvote, the question is clear, and a common one I'm sure most stumble across after doing machine learning work for some time.\nThe goal was to make a stronger predictive model from multiple trained models.\nQuote from my question:\nis it possible to aggregate these 30 fitted models into a single model?\nAnswer: yes but there's no good functionality that allows you to do this in sklearn.\nVerbose answer:\nImagine you have 30 CSV files that contain 15,000 0 class and 15,000 1 class samples. In other words, an equally balanced number of binary responses (no class imbalance). I generated these files myself because 1) the size of the data I'm working with is too big to fit into memory (point #1 of my original question) and 2) contains 97% class 0 and 3% class 1 (large class imbalance). My goal is to see if it's even possible to distinguish between a 0 or a 1 if the class imbalance issue was removed from the equation. If there were distinguishing features found, I'd want to know what those features were.\nTo generate each batch, I grabbed 15,000 1 responses, and randomly sampled from the 97% 15,000 more samples, joined into one dataset (30,000 samples total), then shuffled them at random.\nI then went through each batch and trained an XGBClassifier() using optimal parameters found from GridSearchCV() for each. I then saved the model to disk (using Python's pickle capabilities).\nAt this point, you have 30 saved models.\n/models/ directory looks like this:\n['model_0.pkl', 'model_1.pkl', 'model_10.pkl', 'model_11.pkl', 'model_12.pkl',\n'model_13.pkl', 'model_14.pkl', 'model_15.pkl', 'model_16.pkl', 'model_17.pkl',\n'model_18.pkl', 'model_19.pkl', 'model_2.pkl', 'model_20.pkl', 'model_21.pkl',\n'model_22.pkl', 'model_23.pkl', 'model_24.pkl', 'model_25.pkl', 'model_26.pkl',\n'model_27.pkl', 'model_28.pkl', 'model_29.pkl', 'model_3.pkl', 'model_4.pkl',\n'model_5.pkl', 'model_6.pkl', 'model_7.pkl', 'model_8.pkl', 'model_9.pkl']\nAgain, going back to the original question - is it possible to aggregate these into a single model? I wrote a pretty basic python function for this.\ndef xgb_predictions(X):\n''' returns predictions from 30 saved models '''\npredictions = {}\nfor pkl_file in os.listdir('./models/'):\nfile_num = int(re.search(r'\\d+', pkl_file).group())\nxgb = pickle.load(open(os.path.join('models', pkl_file), mode='rb'))\ny_pred = xgb.predict(X)\npredictions[file_num] = y_pred\nnew_df = pd.DataFrame(predictions)\nnew_df = new_df[sorted(new_df.columns)]\nreturn new_df\nIt iterates through each file in a directory of saved models and loads them one at a time casting its own \"vote\" so-to-speak.", "650" ], [ "The end result is a new dataframe of predictions.\nSince this new dataset is smaller (X.shape x 30), it will fit into memory. I iterate through each batch file calling xgb_predictions(X), getting a dataframe of predictions, add the y column to the dataframe, and append it to a new file. I then read the full dataset of predictions and create a \"level 2\" model instance where X is the prediction data and y is still y.\nSo to recap, the concept is, for binary classification, create equally balanced class datasets, train a model on each, run through each dataset and let each trained model cast a prediction. This collection of predictions is, in a way, a transformed version of your original dataset. You build another model to try and predict y given the predictions dataset. Train it all in memory so you end up with a single model. Any time you want to predict, you take your dataset, transform it into predictions, then use your level 2 trained model to cast the final prediction.", "57" ], [ "Feature Selection Statistical Test for Nominal Response Vs Continuous Predictors? (in R)\nI cannot find much information on this, none so-far useful.\nI have a sparse data set with 17K+ columns of continuous gene expressions, an example of a typical column: (3.15, 0, 7.1294, 0, 0, 0, 2300.2, 213.444,...) and each row has an associated nominal response of celltype = 'A', 'B', 'C', 'D', 'E'. These are names, hence nominal, and not ordinal.\nThus, there are 17308 gene expression columns, and a single response column in my dataframe, with 4954 rows/samples.\nI am trying to find the right statistical test to perform a filter-method for feature selection (taking the best 1000 low-correlation p-values obtained through some statistical test). My teacher mentioned Wilcoxon rank sum test, but I dont see how this applies, nor ANOVA. I found the Kruskal-Wallis as the only relatively good test. I do not come from a statistics background, having only taking Mathematical Statistics I in university.\nI use a File Backed Matrix (FBM from bigstatsr package) to assign the p-values in a foreach loop, as follows:\nforeach(i = 1:num_feats, .combine = 'c') %dopar% { dat_total = cbind(df[, i], df$ctype) p_vals[i - 1, 1] <- kruskal.test(df[, i] ~ df$ctype, data = dat_total)$p.value } but this results in about 12000 p_values stacked up at zero... (?)\nI also tried switching df[, i] ~ df$ctype for df$ctype ~ df[, i] but kruskal.test in R asks for response ~ group, regardless, when I do this I get a bimodal distribution of p-values: a few thousand stacked up near 0 (but non are zero) and a few thousand stacked up near 1 (some equal to 1). I read more on this as in 'Section C' found here.\nI'm supposed to just test each column against the response, check for significance, peel off the best 1000, and then generate a feature reduced matrix df_sml that I then feed into elastic net, lasso, linear discriminant analysis and a classification tree.", "655" ], [ "What I did however was pick the best <PHONE_NUMBER> p-values, and pick the top 1000 that had correlation between -0.25 and 0.25 (LDA was failing otherwise).\nANY tips are appreciated, I don't see the point of deriving a test data set for reproduction. This(and several other) articles mentioned Kruskal-Wallis for categorical dependent versus continuous independent variables (but my concern is I am feeding them in 'backwards' to the test in R).\nI dont understand why I would possibly want to factor celltype into a dummy variable, as this is nominal data and not ordinal data, so any explanation regarding that appreciated. If it is okay, why? Doesn't ordinal data imply rank? And if I am treating the dummy variable as factor, how is that different than treating 'A', ..., 'E' as factors?\nThe simplest method you can suggest would be most appreciated, hence my turn to Kruskal-Wallis and not some of the more complicated and involved methods I have seen suggested (I likely wouldn't have the time to implement them).\nedit: I wanted to add a few things: I ran elastic net for alpha = 0.1:0.9 by 0.2 and LASSO, and I am getting a classification accuracy rate around 0.98 for all of these. So unless something is amiss, my models are getting pretty good results, LDA performed just slightly worse (0.96) than Elastic Net (glmnet), the Tree model with pruning (0.76) was garbage lol. And this was using df$ctype ~ df[, i] which is group ~ response, not the desired format by kruskal.test as far as I know. {see ?kruskal.test(formula,...)}\nedit2: I wanted to add, there are like 8K+ columns with 95% entries being zero, but the teacher said to leave them in and do this test instead (this data is for a machine learning course midterm project), which I've read can be what is contributing to the wild number of p-values stacking up at or near 1. I originally stripped these columns from the dataframe.", "458" ], [ "Assign cluster members using log-likelihood distance metric in python\nWant to clarify that I am pretty new to this area - help would be appreciated :)\nI have 100 clusters, each with a mean and standard deviation value. These clusters are predefined using the SPSS software package, by using the 2-step cluster method. Therefore, the optimisation of these cluster distributions to fit the data has already been done.\nFor new (unseen) data, we want to assign cluster membership by selecting the maximum log-likelihood cluster, for any given set of coordinates X.", "506" ], [ "To do this, I have written my own code for comparison with what was output by SPSS using the same method: https://www.norusis.com/pdf/SPC_v19.pdf\nUsing data that has been correctly labelled by SPSS, about 42% of the clusters are correctly labelled by minimising the RMSE to the cluster mean (which is not what SPSS does), and less than 20% of the clusters are labelled correctly by my code when assigning the maximum log-likelihood cluster (which is what SPPSS reports to do).\nI know that the maximum log-likelihood cluster should be the correct cluster ( https://www.norusis.com/pdf/SPC_v19.pdf ), but there is only a 20% success rate from this code when compared to the correct cluster labels from SPSS. What am I doing wrong?\nHere is the code below.\n``` import pandas as pd import numpy as np from sklearn.metrics import mean_squared_error import math from scipy import stats\nimporta raw files\nclusters_df = pd.read_csv('ClusterCoordinates.csv') # clusters are in order of cluster numbers enabling us to use index for identification clusters_df = clusters_df.drop(columns=['Cluster']) print(clusters_df.shape) clusters = clusters_df.to_numpy()\nframes_df_raw = pd.read_csv('FrameCoordinates.csv') frames_df = frames_df_raw.drop(columns=['frame','replica','voltage','system','ff','cluster']) print(frames_df.shape) frames = frames_df.to_numpy()\nclusters_sd_df = pd.read_csv('ClusterCoordinates_SD.csv') clusters_sd_df = clusters_sd_df.drop(columns=['Cluster']) print(clusters_sd_df.shape) clusters_sd = clusters_sd_df.to_numpy()\nrmseCalc = [] llCalc = [] assignedCluster_RMSE = [] assignedCluster_LL = []\ncreate tables with RMSE and LL values\nfor frame in frames: for cluster, cluster_sd in zip(clusters, clusters_sd): # we compare cluster assignment using minimum RMSE vs maximum log likelihood methods. rmseCalc.append(math.sqrt(mean_squared_error(np.array(cluster),np.array(frame)))) llCalc.append(-np.sum(stats.norm.logpdf(frame, loc=cluster, scale=cluster_sd))) rmseCalc=np.array(rmseCalc) llCalc=np.array(llCalc) llCalc=np.nan_to_num(llCalc) minRMSE = np.where(rmseCalc==rmseCalc.min()) maxLL = np.where(llCalc==llCalc.min()) print(maxLL[0][0]+1) assignedCluster_RMSE.append(minRMSE[0][0]+1) assignedCluster_LL.append(maxLL[0][0]+1) rmseCalc=[] llCalc=[]\nframes_df_raw['predCluster_RMSE'] = np.array(assignedCluster_RMSE) frames_df_raw['predCluster_LL'] = np.array(assignedCluster_LL) frames_df_raw.to_csv('frames_clustered.csv')\n```\nI was expecting the cluster labels assigned by the code to match those already assigned by SPSS, since the methods used are intended to be the same.", "506" ], [ "Comparing distributions Python\nI have a larger dataset (random variable) 'x' containing values approximating a Gaussian distribution. From 'x', a much smaller random variable 'y' is sampled without replacement. I want to compare their distributions using histograms.", "650" ], [ "The code in Python 3.9 is as follows:\n# Create a gaussian distribution-\nx = np.random.normal(loc = 0, scale = 2.0, size = 20000000)\n# Sample from 'x' without replacement-\ny = np.random.choice(a = x, size = 400000, replace = False)\nx.size, y.size\n# (20000000, 400000)\n# Compare the distributions using 'histplot()' in seaborn with different bin sizes for x & y-\nsns.histplot(data = x, bins = int(np.ceil(np.sqrt(x.size))), label = 'x')\nsns.histplot(data = y, bins = int(np.ceil(np.sqrt(y.size))), label = 'y')\nplt.xlabel(\"values\")\nplt.legend(loc = 'best')\nplt.title(\"Comparing Distributions\")\nplt.show()\nThis produces the output:\n# Compare the distributions using 'histplot()' in seaborn with same bin sizes for x & y-\nsns.histplot(data = x, bins = int(np.ceil(np.sqrt(x.size))), label = 'x')\nsns.histplot(data = y, bins = int(np.ceil(np.sqrt(x.size))), label = 'y')\nplt.xlabel(\"values\")\nplt.legend(loc = 'best')\nplt.title(\"Comparing Distributions\")\nplt.show()\nThis produces the output:\nIn my opinion, the second plot is wrong because each histogram should be computed and visualized with it's own bin size for the given data.\nTo further analyze the two distributions using a histogram-\nn_x, bins_x, _ = plt.hist(x, bins = int(np.ceil(np.sqrt(x.size))))\nn_y, bins_y, _ = plt.hist(y, bins = int(np.ceil(np.sqrt(y.size))))\n# number of values in all bins-\nn_x.size, n_y.size\n# (4473, 633)\n# bin size-\nbins_x.size, bins_y.size\n# (4474, 634)\n# bin-width-\nbw_x = bins_x[1] - bins_x[0]\nbw_y = bins_y[1] - bins_y[0]\nbw_x, bw_y\n# (0.004882625722377298, 0.02781399915135907)\nSince 'y' has a much smaller size than 'x', consequently, it's bin-width (0.0278) is much larger than 'x' bin-width (0.0049). Hence, this produces a different histogram and visualization. Since 'y' is sampled from 'x', using Kolmogorov Smirnov two sample test doesn't make sense.\nWhat's the appropriate way to compare these two distributions?", "988" ], [ "KNN Regression: Distance function and/or vector representation for datetime features\nContext: Trying to forecast some sort of consumption value (e.g. water) using datetime features and exogenous variables (like temperature).\nTake some datetime features like week days (mon=1, tue=2, ..., sun=7) and months (jan=1, ..., dec=12).\nA naive KNN regressor will judge that the distance between Sunday and Monday is 6, between December and January is 11, though it is in fact 1 in both cases.\nDomains\n```python hours = np.arange(1, 25) days = np.arange(1, 8) months = np.arange(1, 13)\ndays\narray([1, 2, 3, 4, 5, 6, 7]) type(days) numpy.ndarray ```\nFunction\nA custom distance function is possible:\npython def distance(x, y, domain): direct = abs(x - y) round_trip = domain - direct return min(direct, round_trip)\nResulting in: ```python\nweeks\ndistance(x=1, y=7, domain=7)\n1 distance(x=4, y=2, domain=7) 2\nmonths\ndistance(x=1, y=11, domain=12)\n2 distance(x=1, y=3, domain=12) 2 ```\nHowever, custom distance functions with Sci-Kit's KNeighborsRegressor make it slow, and I don't want to use it on other features, per se.\nCoordinates\nAn alternative I was thinking of is using a tuple to represent coordinates in vector space, much like we represent the hours of the day on a round clock.\n```python def to_coordinates(domain): \"\"\" Projects a linear range on the unit circle, by dividing the circumference (c) by the domain size, thus giving every point equal spacing. \"\"\" # circumference c = np.pi * 2\n# equal spacing\na = c / max(domain)\n# array of x and y\nreturn np.sin(a*domain), np.cos(a*domain)\n```\nResulting in: ```python x, y = to_coordinates(days)\nfigure\nplt.figure(figsize=(8, 8), dpi=80)\ndraw unit circle\nt = np.linspace(0, np.pi*2, 100) plt.plot(np.cos(t), np.sin(t), linewidth=1)\nadd coordinates\nplt.scatter(x, y); ```\nClearly, this gets me the symmetry I am looking for when computing the distance.\nQuestion\nNow what I cannot figure out is: What data type can I use to represent these vectors best, so that the knn regressor automatically calculates the distance? Perhaps an array of tuples; a 2d numpy array?\nAttempt\nIt becomes problematic as soon as I try to mix coordinates with other variables.", "380" ], [ "Currently, the most intuitive attempt raises an exception:\npython data = df.values Where df is:\nThe target variable, for simple demonstration purposes, is the categorical domain variable days.\n```python TypeError Traceback (most recent call last) TypeError: only size-1 arrays can be converted to Python scalars\nThe above exception was the direct cause of the following exception:\nValueError Traceback (most recent call last) in 1 neigh = KNeighborsClassifier(n_neighbors=3) ----> 2 neigh.fit(data, days)\nValueError: setting an array element with a sequence. ```\nI just want the algorithm to be able to process a new observation (a coordinate representing the day of the week and temperature) and find the closest matches. I am aware the coordinate is, of course, a direct representation of the target variable, and thus leaks the answer, but it's about enabling the math of the algorithm.\nThank you in advance.", "392" ] ]

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[ [ "Y Tu Mamá También\n\"life is like the surf, so give\nyourself away like the sea.\"\nlet me just put it out there: <PERSON> and <PERSON> really fuck with each other. literally.\nthis film shows the exploration of friendship between the characters, <PERSON> and <PERSON>, and it is the central theme that resonated with me. their dynamic evolves from carefree camaraderie to a complex relationship strained by their personal experiences and desires.\nthe film beautifully portrays the fragility of friendships as they face challenges, growing pains, and ultimately, the test of time.", "1009" ], [ "this depiction reminded me of the imperfections and growth that real-life friendships go through, making the characters more relatable.\nsexuality is another significant theme addressed in the film. the intimate scenes and candid discussions around sex and desire offer a realistic portrayal of human relationships. cuarón's unflinching approach to depicting these aspects serves to emphasize the vulnerability and authenticity of the characters.\nthis openness challenges societal norms and taboos, sparking conversations about the portrayal of sexuality in media and its impact on our perceptions. so to sum it up, y tu mamá también is a masterpiece that explored themes of friendship, sexuality, and slice of life.", "352" ], [ "Blade Runner 2049\nseeing this was truthfully one of the most captivating experiences i've ever had watching a film at a theater. i absolutely loved it.\nthe way it builds upon the original is exceptional. you can certainly tell it's the same world, but the advances in technology and society and even advertising make for such a fresh outlook. the visuals and score are incredibly stunning. see it at a cinema if you're able to, because the enormity of it all will be enhanced through a big screen.\nnot to be, you know... THAT person but i did prefer this to the original. i found the original to be a stunning film with nice commentary, especially for its time.", "583" ], [ "but it failed for me with characters, some dialogue, and the execution of its plot. with 2049, i found myself really enjoying most characters and sympathizing with them, and the dialogue was strong and subtle. although the plot had some pacing problems, i didn't notice until i was thinking about it after because i was so into everything that was going on, and i was so eager to learn more.\nthematically, it of course had similarities to the original, but i felt much more towards those themes in 2049. the struggle to define what humanity is runs deeply throughout, and following <PERSON> officer <PERSON> as he grapples with this is at times hopeful and then heartbreaking. there is so much going on that can easily be connected to what's going on today, whether it be dependence on technology or the oversexualiztion of women. i love sci fi films where the flaws of the world are heightened to such a grand yet believable scale and that's exactly what this does. <PERSON> is truly a masterful director, and this has become my favorite film i've seen so far this year.", "217" ], [ "Interstellar\ninterstellar man… this is a film that has left a lasting impression on me, and every time i revisit it, it's like a new experience. when i first saw it in 2014, i was blown away and thought it was a masterpiece. in 2017, i considered it the best movie ever (was at my <PERSON> and <PERSON> phase). in 2020, i still thought it was great, but i began to see its flaws. now, i still think it's beyond amazing, despite its flaws. there's something special about this movie that keeps drawing me back in.\none of the most incredible aspects of interstellar is its stunning visuals and atmosphere. <PERSON> directing is masterful, creating an immersive and believable world that draws me in every time.", "462" ], [ "<PERSON> cinematography is breathtaking, and the use of large format theaters only adds to the experience. <PERSON> score is also spectacular and enhances the film's emotional impact.\nas someone who is fascinated by science, i found the film's exploration of <PERSON>'s general theory of relativity and quantum physics to be particularly fascinating. interstellar depicts the theory of relativity coming to life on screen with impressive accuracy, and it's always a marvel to watch.\nhowever, what truly sets interstellar apart for me is its exploration of relationships between human beings, especially the father-daughter bond. <PERSON> performance is outstanding, conveying a range of emotions and experiences with remarkable conviction. it's a testament to the film's emotional depth that even upon multiple viewings, the scenes between <PERSON>'s character and his daughter still manage to tug at my heartstrings.\nthe visuals in the film are also worth noting, with a new technique used to create a more natural and immersive environment for the actors. this technique allowed the actors to react more naturally to their surroundings and created a more believable experience for me as a viewer.\noverall, interstellar is a film that has left an indelible mark on me. while it may not be perfect, its stunning visuals, emotionally charged performances, and thought-provoking themes make it a must-see for anyone who loves science fiction.", "529" ], [ "Fallen Leaves\nman this was depressing…but cute. <PERSON> and his characters say little, but the films say a lot.\n\"the falling leaves, drift by the window...\"\nthere’s just a unique and lovely feeling that comes after watching <PERSON>’s work, even if most of his films are somewhat similar to one another. he continues to make his minimalist yet effective drama comedies drenched in equal amounts of melancholy and glee.", "698" ], [ "they always remain effortlessly engaging and satisfying!\nthe humor, pathos and loneliness in fallen leaves was relatable. the deadpan simple scenes with misunderstandings, punctuated by the karaoke scenes worked really well. athough this is contemporary, it feels like it’s from a different era, without tech. that was so so refreshing but also sad what the world has become.\nalso i loved how <PERSON> leaves nice touches for cinephiles — i could see posters for the Sicilian clan, <PERSON>, <PERSON> and his brothers.", "529" ], [ "The <PERSON>\nit’s an amazing feeling when the high expectations you have for a film are met and exceeded.\nit has been a long time since a film has hit me this hard emotionally. <PERSON> deserves every bit of praise he’s been getting… it’s amazing to see his career revived so perfectly. i can’t see anyone else topping his performance this year. i’m so happy that he got to showcase his talent in such an impeccably written film like this.\n<PERSON> and <PERSON> gave such memorable performances that was elevated but also owed to by an equally talented writer.\n<PERSON> briefly spoke about the process of writing this movie at my screening, and for his first screenwriting job on a film, it is insanely good. he’s really piqued my interest in seeing what else he does in the future, because he’s already left such an impact on me with this solid screenplay.\nfinally, it was also so exciting to see <PERSON> at my screening too.", "529" ], [ "seeing one of my favourite filmmakers up close was so special! i especially admired him talking about the process of choosing <PERSON> for the film. however, most of all, i love how different yet similar this film feels in comparison to his others. it’s the perfect balance of his typical intense style and a newfound tenderness and differing exploration of fragility. the whale felt like the perfect way for him to showcase his trademark ideas, all whilst introducing new depths he hasn’t touched upon before. once again, he’s proven how he’s one of the best directors from the 21st century.", "594" ], [ "<PERSON>\n“we still love each other, right?”\nmommy is such an incredibly disturbing film. <PERSON> offers such a complicated examination of a mother-son relationship and what it means to truly love someone unconditionally.\n<PERSON> truly hit the ball out of the park with this film. there is such an intensity that carries through the whole film from start to end without it ever feeling bogged down by sudden climax’s or dilemmas. this is probably my favourite <PERSON> film to date.", "529" ], [ "i think it truly encapsulates all that makes him such a unique and great director. he has such a unique style when it comes to presenting his stories. i know some people find it pretentious, but his use of aspect ratios mainly in this film, but also out of focus scenes, shots that are a little too close, all staples i associate with a dolan film. not to mention the cinematography is always stunning and the score on this film is especially delightful.", "594" ], [ "Welcome Back, Mr. <PERSON>\n\"radio, like a bento lunch, has a lot of variety.\"\n\"welcome back, mr. <PERSON>\" is one seriously funny comedy that takes you backstage into the wild world of live radio. the whole deal is about the madness that goes down as they gear up for a radio show. the actors, led by <PERSON> and <PERSON>, totally nail their roles and bring out the hilarious sides of their characters.\nthis movie weaves different stories and personalities into a fast-paced plot that keeps the laughs rolling.", "585" ], [ "even though it's mostly a laugh riot, there are some touching moments when you get a peek into the characters' personal struggles. <PERSON>'s character brings a touch of sincerity to the chaos. amidst all the craziness, there are these beautiful moments where you see her vulnerabilities and the struggles she faces.\nin essence, the film is a hilarious and heartwarming film that gives you a peek into the world of live radio. with a fantastic cast and great direction, it's a movie that will keep you laughing and entertained. if you're up for a fun and unique comedy, this one's definitely worth watching.", "529" ], [ "Pan's Labyrinth\npan’s labyrinth is an upsetting coming of age film that explores the rights and wrongs of the world in a horrifying fantasy world.\nthis is not a happy story but there is a sense of hope and relief at <PERSON>’s story. her willingness to rebel isn’t bad.", "352" ], [ "so often as children we’re thought to shut up and listen to adults, but <PERSON> doesn’t. and that is a good thing. what we are thought or raised with isn’t always the right thing and <PERSON>’s labyrinth showed that beautifully through <PERSON>’s fantasy’s and rebellion against her stepfather.", "352" ] ]

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[ [ "What to do with 10 dogs that need rehomed within 30 days?\nMy parents are being evicted from the property they've lived at for 20+ years. They have 10 dogs who are all unfixed, in generally poor care and have formed 3 packs amongst the whole of them that will attack each other on sight.\nThey have 30 days to get rid of all these dogs so they can move with peace of mind. Yes, its really trashy and sad. Thats why I've been living out of state away from my parents for over 10 years now and don't talk to them much.\nHarmful, judgmental comments are not constructive, even if justified considering the situation.\nWhat are their options?", "661" ], [ "I now have an \"outside cat.\" Is that as bad a thing as I've always been led to believe?\nFor context, I live in an apartment block and there are quite a few stray cats around here. Recently, I noticed one was hanging around my back porch and the steps near my apartment. I live on the bottom floor, so I've been leaving some water and food out as it's been pretty hot out lately.", "311" ], [ "Since I've been doing so this cat has gotten familiar with me and my GF and has been exclusively hanging out on my back porch or near it. She can't be more than 8 or 9 months old and is sweet as pie. She lets us hold her, loves belly rubs, and is surprisingly healthy, but still obviously feral.\nI've tried to reach out about rehoming her, but there are more people trying to re-home stray cats than there are people adopting them in my area, unsurprisingly. I reached out to humane societies and they're full, and a normal shelter told me she'd likely be put to sleep after a month because they're also full to the brim.\nI'd love to bring her inside, but I already have 2 elderly animals that barely tolerate each other and I know it just wouldn't work.\nAs long as I'm giving her food and water, and if it comes to it, vet care, is keeping her outside so terrible? I plan on getting her shots and maybe fixed if I can find someone to watch her while she recovers.\nI know keeping a cat outside is generally considered not cool, but when circumstances don't work out am I doing such a terrible thing?", "664" ], [ "I don't know what to do with my dogs.\nSo, I recently moved into a house with a yard (fully enclosed) for the first time, and in a really safe area. Awesome, I figured, I can leave the kitchen door, where their crate is, open to let them run around.\nProblem is, the last few days, they've become increasingly destructive. They ripped up and ate two of my potted plants, and, this morning, ripped apart a wooden crate. They have their own toys, but seem to be more interested in destroying everything else.\nHonestly, I'd appreciate any ideas.", "661" ], [ "How can I convince my ignorant grandma that petting her cat twice a day, then being gone + asleep for 21 hours a day is neglect, and that she needs to get her a companion?\nThe title is pretty self explanatory. Her last cat was living under this exact condition for much of her 14 years before she passed in August.", "601" ], [ "She was extremely bored and depressed-looking, was left alone nearly the entire day with no one to pet her or give her affection, aside from for a minute or 2 in the morning before work, then the same after work, before falling asleep an hour later. She pretty much just plans to do the exact same thing with her new cat. I tried to bring this up with her that this literally is neglect and she will get depressed on her own without anyone to look after her, but she just said that i'll be here despite me moving out this weekend and that she can only have 1 animal when shes had her last cat + me literally having multiple rats while I've lived with her.", "679" ], [ "Can't move my dog to a new vet.\nPrevious owner moved to Australia 16 months ago. Original plan was I'd foster care until he could arrange transfer.\nAfter a while of keeping her we both decided it wasnt fair on the dog to put her through the stress of travel and she'd be better staying with me. All agreed, all fine.\nTrouble is he is awful at communications.", "1011" ], [ "I've transferred the microchip on the basis that he had 30 days to respond and after that it just automatically transfers.\nHer current vet is Vets4Pets, miles from me. I keep ringing asking them to change the ownership to me, and they can't until he replies to an email they sent. That was 2 months ago and he hasn't replied.\nI'm stuck because I don't know what else I can do - I ask him to reply to the email and he never does.", "498" ], [ "Leaving small dogs in our house for 2 weeks while on vacation\nHey all, My mom decided that it’s too expensive to board our dogs in a doggie daycare, and that my dogs will be more comfortable being in our house. She hired our cleaning lady to pet sit our dogs.", "881" ], [ "She committed to coming in our house once every morning and night to walk and feed them. I am still feeling anxious and I am nervous about our cleaning lady fulfilling her commitments as she lives half an hour from our house.\nHas anyone else done something like this before? I know boarding them is ideal, but our older dog literally got traumatized from being boarded as the day care had him Play (small 9 pound yorkipoo) with big dogs who ended up hurting him. So we dont want to risk something like that again with him and our younger dog.", "63" ], [ "Why have an outside pet?\nI've never understood the point of keeping an outside cat/dog. My neighbor had a really friendly chubby cat, but she was an outside cat that was unfortunately ran over a few days ago after being away for a while. I felt so bad, but also felt that could have been prevented if she monitored the cat better.", "679" ], [ "There are many dangers to these creatures, from vehicles running them over, someone taking or harming them, predators, and injuries/diseases that can be prevented when they are homed inside. Personally, I think pets should have the care, resources, and love from inside the home. I understand some people don't those same options as others. Just wanted to hear from some people who have \"outside\" pets, how do you manage their safety, especially those pets who run off for days at a time and why?", "661" ], [ "Are cats more affectionate when recovering from something?\nOr maybe its because he is an outdoor cat. Anyway, I've been feeding and gaining the trust of 4 feral cats for over a year, since they were kittens. Prior to this, I had no care experience with cats, as all my pets have been dogs. I was able to gain their trust enough to pet all of them and pick up 3 of them (the other is a VERY flighty and sassy calico, so I rarely try to pick her up).\nThe other day one of them had half of his tail entirely degloved down to the bone. We don't know from what, but luckily the vets said it was a clean wound and not a bunch of torn ligaments.", "961" ], [ "They amputated it and told us to keep him in doors, which we were hesitant about as our home is not cat proof, but decided to keep him in a bathroom as I've seen people on YT do with newly adopted cats.\nHe usually is not that affectionate. Yes, he will let us pet him and likes his neck scratched but he doesn't seek us out that often. But as of now (its only been 2 or 3 days), he is on constant purr mode when I enter the room, pacing back and forth to get me to scratch his butt or neck. He also rolls over on the floor, like his brother (the most affectionate of them) does when telling us \"oh get this spot here\" (he is very spoiled lmao). This morning he climbed into my lap and laid down to go to sleep. When I tried with any of them before to put them in my lap, they'd immediately jump down.\nSo is this normal?", "311" ] ]

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[ [ "What observable traits set the MilkyWay apart from other Galaxies?\nIn a short story, Earth's humanity dies off to a plague and a few thousands years later a space faring race plants a new seed of humans in attempt to restore what civilization used to be.\nThe Earth is effectively the same, though biomes may change and a couple thousand years of wild evolution have passed (so a wild dog might look a bit different but it's still clearly a canine). The method of \"planting the seeds of civilization\" is apparently instantaneous to the humans, as if one day, everyone just woke up as if they had just gone to sleep normally the day before. At that point, the seed planters take their leave and observe from afar without interaction. (The story spans hundreds of years as they observe)\nIt's just one big city, outfitted with the tools and resources necessary to farm, process, and produce what a population of that size would normally consume. The humans have been granted the know how on how to operate the machines and build a sustaining civilization. Satelittes and cell phones don't exist but they would later be reinvented. Their next generation being the first humans that actually would need to learn how to walk, talk, read.", "302" ], [ "Their parents are somewhat programmed to work together in building a sustainable \"start\" to the civilization (even if they aren't exactly aware as to why) and would come off as very literal and set in their ways while their children are more creative, looking at the world in increasingly philosophical ways.\nOther than the knowledge of the world around them and how to survive though, these humans do not have a living past in memory. They don't have a notion of \"where did we come from\" and this first generation largely doesn't care. Their children though ask such questions, using the tools and technologies we have now and in the near future to rediscover the universe outside of the Earth. This generation spawning a renascence of invention and discovery in the absence of war and while crime is still a distant concept while everyone's needs are met. Some conflicts arise between competing theories and discoveries.\nWithout a history, polytheist stories (where the milky way got it's name in reality) or previous inspirations, they need something to name it. What observable traits set the Milkyway apart from other galaxies? Also keeping in mind they don't have a distant probe to view it from anywhere but Earth. They can see distant galaxies while they are deciding on a name.\nThis naming period may last a few years as these fresh explorers catch up to our current IRL astronomical knowledge and begin sending out orbital telescopes similar to our own.\nTypical DM brain, I can make a world, but fail to find a good name.", "693" ], [ "Unintended implications of using a celestial object as a \"weight\" for a digital currency?\nI have a sci-fi universe that's meant to be astronomically accurate, scaled around cataloged stars and known open clusters/nebulae like the Orion Complex or the Hyades. Space faring civilizations rely on luminous stars for FTL as the more luminous stars generate a special particle* any interstellar civilization needs. Aliens are more alien, but not xenocentric (though they're not relevant here).\nIn the year 2421 Humans are partially unified (but historically was completely unified) under FAHI-The Federal Association of Human Interests. A notable tenet FAHI has is that the organization claims sovereignty on part of every human being and in theory acts on the part of human interests. In practice FAHI ended up acting on terran interests instead due to poor representation for people living in the colonies. A side effect of FAHI making mass colonization of space one of its main tenets.\nIn order to make a universal currency for humanity that wouldn't to subject to financial fluctuations, the ministry of finance decides on using the mass of a nearby celestial object to give a set weight to the digitized \"universal\" human currency. There is a set limit of credit that exists in circulation in order to avoid inflation, of which is set at 100 trillion credits.", "302" ], [ "The currency's value is centered around said celestial object. I am a bit back and forth on what celestial object, but for now assume one of the following possibilities:\n* Sagittarius-A* super massive black hole\n* The Milky Way Galaxy as a whole\n* The Sun\n* A Nearby neutron star (Like Calvera)\n* Earth\nNot sure which one would be the most logical or thematic, but the general idea should be the same. A currency that has its weight not in gold, but in a celestial object of arbitrarily defined importance. The issue is I have no clue if using a cosmic object as a currency weight would actually work in practice given the expansionist nature of my human civilization.\nSince I am not really good at economics, can anyone who knows their economics tell me what unintended implications of this idea may entail given the scenario and/or celestial object used? I'm not completely sure where to look.\n*Detail: The \"special particle\" in question is called the \"Lux Particle\". It exists only in the corona of stars and must exist in plasma. Lux Particles allow ships to not only have FTL, but also fast-as-light travel and teleportation for spaceships. Brighter stars have more lux. I might have intentionally devised lux as a way to screw red dwarves over.", "302" ], [ "Very tribalistic\nWhile there may be some genetic mixing, your clone has to be pretty much the same dimensions as you. I'd imagine most phenotypes would be shared between the two. More importantly, if memories are carried over it stands to reason that dogma is transferred over from birth. Wrongdoing from generations ago could carry over as what feels like first-hand memories, but with much more time to diverge from the truth. While in the real world children are taught who the enemy is in this world everyone knows from birth. At the same time, everyone from the other tribe also carries memories of traumatic events (albeit likely very different from yours). While most people consider it wrong to harm children for the wrongdoing of their families no one in this world is ignorant of history and everyone in a lineage may be considered responsible.\nFewer, but more intense taboos\nWe're all adults here everyone is mature enough to curse and talk about reproduction. That said if something is taboo everyone already knows from birth taboos never need to be explained or discussed unless of course, you aren't part of our lineage. A very big difference from humans is that people could potentially remember their birth perhaps the moment of splitting. This could be a more celebrated moment like human birth or something done behind closed doors like sexual reproduction. Either way, there would likely be all kinds of ritual and taboo surrounding it.\nHighly optimised, but less revolutionary\nIt's diffuicult to say how the tasks of a person are delegated to the two new people however it's very likely that they would pick right where they left off. Perhaps the siblings will work together or perhaps they will take on different interests (finally get to start that rock band!). Because memories are kept, there is no training needed for a newborn to get to work which will allow larger projects to be completed faster and with more consistent vision. If the siblings work together they would likely have great synergy starting off with the same amount experience (built over generations) and an intimate understanding of each other.This combination of expertise and solid teamwork would lead to highly optimised products and more success in feilds like math where problems can take generations to solve and many years to even understand.", "335" ], [ "That said with such levels of experience, it would be hard to break into a field or industry which can cuase stagnation. Siblings could prevent this by tag teaming. One works and the other goes on a sabbatical then when the working sibling burns out they switch places to bring a new perspective while minimising the amount of time need to learn the ropes. This can be extended to the whole family tree with a variety of degrees of involvment that regularly changes in accordance to experience, and fresh perspectives (which are somewhat opposed and both inherited) like a royal bloodline however it would be built on experience and knowledge retained making it more utilitarian than human bloodlines. This provides plenty of opportunities for factions and rivalries forming feeding right back to tribalism.\nNot into cuteness or dating\nChildhood and parenthood are incredibly important to forming familiar bonds. Without childhood, relationships in this world would probably built on generations of interaction more along the lines of a fellow countryman. There would be no maternal instinct and no sense of cuteness so say goodbye to Hello Kitty. Without sexual reproduction, there would be no biological drive for romantic relationships. That's not to say there would be no romantic relationships just that they wouldn't be common and may even be frowned upon. Romantic relationships are unlikely to be codifed with concepts like staying faithful or being committed so each relationship would be unique in it's expectations rather than falling into defined categories like dating, boy/girlfriend, and married. It's also important to remember that eventually your significant other will split in half if they don't die first so dating is either short lived or very open. I'd like to mention that people would probably have a weak sense of individuality since they carry the memories of past lives and know that their body and mind will be split and morphed. A sense of self is very important to forming personal relationships so they wouldn't be very common. Overall, the lineage comes first.\nHope this helps best of luck!", "1008" ], [ "I can think of three ways that the humans might be able to communicate with each other without the superior AI catching on to it.\nPoetry\nAs mentioned in the question, an artificial intelligence, though it can mimic the analysis or prose and artful devices, only a human can really appreciate the ideas and concepts captured by a poem. Note that the use of a poem would not reveal messages in plain sight but use literary devices to convey the idea rather than exact phrasing.\nAdvantages\nThis seems like a better way for humans to communicate their feelings about situations and their love for each other (maybe?). This also is easy to learn and pickup, and even with the AI's massive database of poetry, even with the ability to add new intercepted poems, it would not become easy to break.\nDisadvantages\nCommunication has a lot to do with clarity and poems may not be the best pick for this, as different people can interpret the same poem with different results.\nCode with Virus\nPerhaps the only weakness to this AI is anything written/spoken must be passed through some interpreter/compiler, and this means the AI could be hacked.", "634" ], [ "As part of the developmental process of the AI, rather than \"escaping the code\" to prevent a virus from running, the AI was developed to \"skip over\" code that it recognizes contains a virus.\nWhen the humans discover this vulnerability, they develop loads of viruses and attempt to shut down the AI. Now, however, the remnants of the viruses they learned and tried to use against the AI, they use as the header of footer of messages with each other.\nAdvantages\nThis completely prevents the AI from reading and learning anything from a human's message.\nThe human's can communicate their message directly, as they know where to look for the actual message and ignore the header and footer code that is the virus.\nDisadvantages\nHumans have to remember and retain the code that is a virus and write it perfectly. This could also mean it takes longer to \"encode\" their message.\nIllogical Statements\nIn the second <PERSON> movie (featuring <PERSON>), <PERSON> and his brother communicate with a simple code that makes complete nonsense to an outsider. They flipped any all truthiness of statements (like: \"I love you\" becomes \"I hate you\").\nThe humans have found that using this coupled with using sentences like, \"this statement is false,\" utterly confuse the AI, resulting in the AI ignoring/failing to process their message.\nAdvantages\nOnce learned, the humans could get in a habit of this and learn to communicate quite easily.\nDisadvantages\nThe learning curve might be harder than I imagine.", "634" ], [ "Approximately the same time as it has taken the original to arrive at the same age and physical condition, obviously!\nYet this may not quite be acceptable from a plot point of view, so here's a few pointers on reducing that time frame, contingent on the use of the clone.\nSpare parts\nYou don't actually need a full clone for this, it should be possible to graft the organ to be replaced onto a bio-compatible host and with growth/rate accelerators you'd be looking at several months to years. Some organs are problematic: the brain, for instance (we simply don't know enough about the interconnections between all the neurons except that these interconnections are partly created through learning by the individual), but also muscles as muscles need a work out to be compatible with the individual receiving the spare part. On the bright side, you can require some re-validation therapy and it may be advantageous to use a younger version of an organ.\nRejuvenation\nThe practice where a much younger clone is used as a replacement body when old age becomes a hindrance. This requires a mind transfer technology which presumably fixes the neuron and neuron interconnection problem. There is plenty of time to grow a body (say, twenty years) and the clone body does not need much exercise and can be kept unconscious during the entire growth cycle. A period of up to a year of exercising the new body after the mind transfer (the old mind has to adapt to the much younger body) is probably acceptable as well.\nReplacement\nThe practice where a clone body is offered as a replacement in case of accidents or after being murdered.", "335" ], [ "Again, this requires a mind transfer technology in addition to regular mind recordings as a backup to restore onto the blank slate. This is one of the more difficult use cases as it requires the body to be grown fairly fast, say less than five years, while keeping it a blank slate. Another problem is to copy the physiological impact of the environment on the new body, i.e. scars, wear and tear, and so on. Without this the clone will not have an identical or even similar look! Again an adjustment period of the recorded mind to the new body of a year is acceptable.\nReplication\nThis is the use case where the genotype of successful individuals are copied to augment (or supplant, whatever the plot is) the general population. The problem here is to copy the environment and learning processes too as the phenotype is the determinant of success, not the genotype on its own. However, decades to grow and learn a clone into an individual are permissible, as each copy will be an individual, albeit very similar to another copy.\nOther uses\nThere are probably other very creative uses of clones but the main things to consider are:\n* in how far does the phenotype (result of environment and genetics) of the clone need to match the original? A blank slate is much easier than a fully trained individual.\n* how much time do you have to prepare the clone in advance? If you need anything less than a couple of years, I'd seriously look into biological 3D printing and infusing the 3d printed cells with the DNA from the host.", "335" ], [ "All forms of reading becomes inherently dangerous.\nTL;DR - Readers develop a short form of pre-reading to \"hash\" the text and compare the hash to known enthralling patterns to detect traps. \"Abandon your mind to the...\" becomes \"Abyo Mito Ta..\" (nonsense words) which don't mean anything to the reader other than, \"this is a trap\"\n* It cost no mana (no magic response)\n* It cost few money\n* Protect you even when you are not ready\n* Allow you to read what you want, in every language you know\n* Doesn't take time\nOnly costs a second or two when reading something to check the hash, and the education to learn and enforce the habit among the average reader.\nThough this isn't the only way the world would react to this possibility.\nThis threat would be akin to mass mailing anthrax IRL\nThis would be a global security concern if stealing someone's mind and making a thrall out of them was really this simple, amassing slave armies every time you put up a new billboard, entire wars could be won by painting your words in the clouds above or using illusion magic to \"pepper spray\" an attacker with hovering symbols that a fast reader simply glancing at would fall prey to. To then have the concentration and effect sustained by the target itself thereafter, that's no simple task.\nThis must be either, much more difficult to perform than explained, or newly discovered and never used against the world yet.\nA less severe version may be a book that contains a glyph which houses \"Command\" or \"Suggestion\" like effects to \"READ\" or to continue reading the control spell until finished, so that the hook has a definitive sink that can either be resisted or fallen for. From there, the duration of time to read the enthralling symbols is all that waits for the effect to stick long term, though the compulsion to read doesn't mean the target isn't aware of what's being read.\nA commoner likely would just read and absorb the information but a wizard would likely be able to identify the intent of the trap setter by understanding the template of words being read. As in general safety training, specific dangers as these sorts of traps would be wise to teach in schools to prevent strong magic users falling prey to these simple traps.\nI believe the response to such an attack would be immediate, urgent, and far spread when detected.", "227" ], [ "Once discovered every magical defense program would be working to put an end to it and devise ways to find who set the trap.\nThis gives us 4 points of resistance\n-Before you see the hook but are within threat range.\n-The compulsion to continue reading once the hook is activated.\n-The formation of the lasting enthrall effect while hooked.\n-Post attack response.\nBefore you see the hook but are within threat range.\nImportant places such as government buildings etc will be outfitted with Magic Dispelling gateways. When walking through, all magical items much be handed to a guard/wizard to be checked via detect magic to determine any enchantment or illusion school magics (if detected further probing occurs), while everything else and the person passes through a dispel magic portal. This removes any magical effects present in items or creatures passing through (no disguise self allowed) and the magic within the text that creates the link between the trap setter and the target is removed, disabling the trap.\nIn general, an enchantment effect found using detect magic on either an object or person would become much more suspicious and actionable, towns likely setting up guard patrols specifically containing magic detectors to scan areas regularly as a result.\nThe compulsion to continue reading once the hook is detected.\nReaders would be trained to read in a way that disrupts direct thought injection attacks. Rather than reading entire words, a learned habit to replace words, shorten words, or rearrange the words read can be used as a passive defense. Rather than reading \"Abandon your mind to the...\" would instead be read as \"Aba-yo mi-tota...\" which will become a barrier allowing the reader to understand abstractions and concepts indirectly (imagine a code hash) and compare that abstract with commonly used \"enthralling\" patterns to determine that an attack was attempted before reading any further. Correspondence to high importance folk would filter through a scholar that could screen for traps.\nAdditionally, divination sensors can be set to Alarm whenever \"I am magically compelled to do something\" to emit concentration breaking sounds or to alert others nearby that they have been enchanted on repeat (imagine magic mouth necklaces in DnD5e).\nThe formation of the lasting enthrall effect while hooked.\nContingencies and emergency response could be pre-planned, \"If I am ever magically compelled to do something, cast dispel magic/banishment/etc on myself and send a message to X for help.", "227" ], [ "Future earth, dystopian fantasy novel. Late 20th century scifi/fantasy\nI listened to the audio recorded reading of the first chapter or so of a book (probably illegality uploaded) on youtube in 2016.\nThis book seemed old, I'd date this work back to anywhere between 1960 through to early 1980.\nThe setting was a post nuclear Holocaust Earth where tribes, kingdoms and warlords clashed. There was magic or the belief in magic as it was remembered when a necromancer had threatened the balance of power in a time shortly before our story. There were also monsters, likely the result of genetic misshapen, that stalked the land. One such monster actually was the subject of the first scene. I'll describe it as it encounters the character.\nThe first and only character I met in this chapter (or prologue) was an older man, considered a knight/hero of times past but perhaps on the dellcline; he had proven himself in battle and defended the common folk from danger in tempestuous times. He was a leader or at least a great warrior.\nIn the first scene the hero was traveling and happened down to a bog. In this bog he reflected on the danger of such places, noting mentally that a particular type of swamp creature roamed such environs; though nearly extinct following the defeat of the aforementioned necromancer there still lingered reports of fighters going missing in the wilds these beasts were said to roam.", "1012" ], [ "One that was intelligent, cruel, had a taste for men and horses and maybe enjoyed torture. (I remember it being called a gibbeth/gibbon/G-something) This thing was definitely a product of radiation and nature and perhaps dark magic because it bore a resemblance to humanity in it's face, it's intellect and it's tactical awareness (preferring ambush tactics)\nWell it so happens that our main character. witnesses a herd of horses fleeing away from this swampy area. The fear in their eyes indicates that in fact one of these monsters was accosting them. Horses were highly revered in this setting so the hero investigates. He finds the monster responsible in pursuit of the prey not long after, and though these predators were more than a match for several, men the hero engages. The hero outwits the creature by pretending to be injured by one of its attacks and baits it into a decapitating counterstrike. It dies headless with the relishing smile still on it's face at the prospect of dragging our hero off.", "999" ], [ "The sheer closest I can fathom for an empire limited by the speed of light is <PERSON> from A Deepness in the Sky. And I swear I've writtenabout them on WB (or atleast on SE somewhere) before, but I can't find it. A few other people have with regards to a few topics.\nThe Qeng Ho weren't an empire as such, but a loose collection of disparate groups that all held the same ideals and goals; essentially a societal norm spread across light-centuries.\nThese groups would fly between known civilized worlds and trade in whatever might be of value. Sometimes it would be technology, or it might be goods, or it could be information. Occasionally they would arrive and find the planet having bombed itself back to the stone age and the Qeng Ho would aid in rebuilding a space faring society because they knew that in 100 or 200 years another Qeng Ho ship (them or someone else) would be by again and the planet would have valuable trade once more.\nThe backbone of what made them functional was--effectively--a galactic radio station. Every Qeng Ho ship would broadcast an automated signal that would contain the blueprints necessary to go from radio (\"are you recieving? Build this...\") to intra-solar space travel.", "302" ], [ "As well as things like language and the society of the Qeng Ho themselves, so that when the traders showed up, they could parley with minimal effort.\nUnderlying that was a private Qeng Ho encrypted channel that allowed groups to talk with each other. Not quickly, but still faster than their ships could travel. They'd use this channel to broadcast locations of new civilized worlds, premium technical advancements (the <PERSON> kept the best stuff to themselves), and so forth. They knew that any given message may never be received, much less generate a reply that they would hear in their lifetimes (even long as they were due to relativistic time dilation and life prolonging technologies).\nBut I wouldn't call them a K3 civilization, necessarily... Just the closest thing to \"a galaxy-sized society limited by the speed of light\" that I am aware of. And I'm not 100% sure that this would truly work, but it is plausible enough for a novel.", "209" ] ]

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[ [ "I would assume here that adding/removing edges/vertices will be done one at a time. Please take note, the term node is used for a node in a linked list and I tried my best not to use it interchangeably with the term vertex.\nThe structures for storing vertices and edges\nLet A be your adjacency list for the graph.\nLet V be an array (ordinary/associative depending on your actual vertex representation) of pointers. An entry in V points to a vertex stored in the structure D given below.\nLet D be a doubly linked list. A node n of this list holds two data: d an integer that represents the degree and a doubly linked list l containing all vertices with degree d. We shall maintain that the nodes of D are ordered in increasing value of d. You can think of nodes in D like a bucket containing all vertices with the same degrees. D will have a tail pointer that points to the end (bucket containing vertices with maximal degree).\nInitially, D only has a node n0 such that n0.d = 0, which will contain all newly added vertex (assuming that newly added vertex has no edge yet).\nThe entries of list l are vertices with degree d. Each vertex v in l has a pointer b that points back to the node in D where l belongs.\nAdding a new vertex\nWhen you add a new vertex v, create an entry in A and add it to n0.l and finally add an entry in V that will point to v in D. Set v.b to n0.\nAdding and removing edges\nWhen a new edge (u,v) is added, add the nodes (using the procedure above) if they do not exist yet. Update the entries of A. Then, follow the pointer of u in V.", "835" ], [ "At this point, the degree of u will increase by 1. Follow u.b pointer to get the node n in D containing u. Let n' be the node following n in D. If n'.d = n.d + 1, transfer u to n'.l. If n' does not exists or n'.d > n.d + 1, insert a new node m after n such that m.d = n.d + 1 and transfer u to this node. Update u.b. If after this n.l becomes empty , delete it, except when n = n0. Do the same update to vertex v. Finally, update the tail pointer of D in case the the last node in D changes.\nWhen you remove an edge, you can simply reverse the process of adding (I will leave this one for you to think about).\nRemoving a vertex\nRemoving a vertex v can be implemented by first removing all its edges one at a time using the edge removal procedure above, then finally removing v from D, V, and A.\nAnalysis\nUpdating the edges of a vertex and maintaining the order of D after adding a vertex and updating edges takes $O(1)$ time (ignoring the cost of adding a new entry in A and V which is dependent on how you implement them). This is because we only need to follow and update constant number of pointers and create/remove constant number of nodes in the linked lists.\nAs for the removal of a vertex v, the time is $O(deg(v))$, which I think is optimal since you have to update that many vertices too since you have to update the neighbors of the removed vertex.\nEach entire representation requires $O(n)$ extra space for the pointers and linked list nodes for each vertex. This is $O(1)$ additional space per vertex.", "835" ], [ "tl;dr I wrote some solution but realized it is not perfect. Since I didn't want all this typing to go waste I figured I might post my observations here rather than splitting them in the comments.\nI think that the problem can be solved for any arbitrary $s,t$ and $x$ in $\\mathcal{O}(V+ E)$. In fact we can extend the problem to answer $Q$ queries of the form $(s,t,x)$ with $\\mathcal{O}(V+E)$ pre processing and $\\mathcal{O}(1)$ per query. I am having trouble completing step 6, but I am pretty sure that it can be done. Someone in the comments may know.\n1. Find all strongly connected components (scc) of the graph using Kosarjau's or <PERSON> algorithm. This step will take $\\mathcal{O}(V+E)$ time.\n2. Using a hash table, you can check if two nodes belong to the same stongly connected component in $\\mathcal{O}(1)$ time.\n3. If two nodes $u$ and $v$ belong to the same strongly connected component, then there exists paths both from $u$ to $v$ and $v$ to $u$.\n4.", "835" ], [ "Now what remains to be checked is if two nodes $u$ and $v$ do not belong to the same strongly connected component, does there still exist a path from $u$ to $v$.\n5. We will modify the given graph $G$ to a new graph $G'$ which we shall call the strongly connected component graph or scc graph for short. In the scc graph, each node corresponds to one strongly connected component in the original graph i.e. we compress all nodes belonging to the same scc to a single node. It can be proven that the scc graph is a Directed Acyclic Graph (DAG for short).\n6. Now our task reduces to check if there exists a directed path between $u$ and $v$ in the DAG. Topological sort can give an ordering such that for any path from $u$ to $v$, $u$ will appear before $v$ in the ordering. Thus we can check if index of $u$ in the topologically sorted sequence of vertices is less than that of $v$ in $\\mathcal{O}(1)$ but this method also gives false positives and this is where I am stuck.\n7. I feel that we can augment step 6 with some additional data to complete the algo. One method I was thinking of was to maintain some constant $K$ number of random topological sorts and if the inequality $index(u) < index(v)$ is true for all $K$ sequences then we can conclude with high probability that there is a path from $u$ to $v$.", "433" ], [ "While waiting for your updated post that includes your solution, I have posted mine:\nSolution\nA substring is deletable if all its characters will be deleted based on your requirement. This substring may have several groups of repeated characters. For example, if the string is \"accccbbbdddagggde\" then \"cccc\" and \"bbb\" are deletables. A deletable substring is maximal if it is not adjacent to any deletable substring.The examples earlier are not maximal deletable substring, but \"ccccbbbddd\" and \"ggg\" are maximal. An undeletable substring is a substring that will remain in the string. A maximal undeletable substring follows the same idea as maximal deletable.\nYour problem is essentially to remove all maximal deletable substring in a string, and then append the resulting string with as many 0 as the removed characters. Below is a solution:\n1. Let $cur = -1$ be the starting index in the array that can be overwritten. Initially, there is no index to overwrite. Let $count$ be the number of characters that will be removed.\n2. Scan the array until you find the left-most maximal deletable substring $d$. Let $d_{start}$ and $d_{end}$ be the start and end index of this string, and $d_{len} = |d|$ be $d$'s length.\n3. Continue the scanning to find the maximal undeletable substring $u$ adjacent to $d$.", "242" ], [ "Let $u_{start}$ and $u_{end}$ be its start and end indices and $u_{len} = |u|$ be $u$'s length.\n4. If both $d$ and $u$ exist, do the following:\n5. If $cur$ is still -1, set $cur = d_{start}$.\n6. Set $count = count + d_{len}$.\n7. Copy substring $u$ at position $cur$ all the way to $cur + u_{len} - 1$. This essentially moves substring $u$ to the left, overwriting $d$, entirely or partially, depending on whether $|u| \\ge |d|$.\n8. Move $cur$ passed the copied substring, that is let $cur = cur + u_{len}$.\n9. Go back to step 2, but the scanning will start at $u_{end} + 1$.\n10. If either $u$ or $d$ does not exist, write as many 0 $count$ to the array starting at position $cur$, and we are done.\nAnalysis\n* This solution uses only $O(1)$ extra variables, hence it uses $O(1)$ extra space.\n* It overwrites an index of the array once. Either at step 4, when moving an undeletable string to the left or when writing 0's at step 5.\n* This solution runs in $O(n)$ time. Observe that an index is visited at most twice, once when it is considered in the search for deletable/undeletable substring and the other when it is overwritten. Finding a deletable and undeletable takes time $O(|d|)$ and $O(|u|)$ resp., while moving an undeletable takes $O(|d|)$ time. In the worst-case, all substrings in the string will be classified as is either deletable or undeletable. Since indices are written at most once, the total time of finding and moving all such substrings is $O(n)$.", "743" ], [ "You can use your lists of list representation. But your main list $M$ will be a circular, double linked list. A new row will be inserted at the head of $M$, which takes $O(1)$ time. Each row will store its own row position $p$. Now, it's possible for multiple rows to have the same row position at any time. Say you insert $r_i$ first as row 0 then $r_j$ next, again as row 0. Inserting $r_j$ should have \"pushed\" $r_i$ one position forward, however we will not update $r_i$'s position until later. Note that $r_j$ will appear in front of $r_i$ in $M$. In general, it's possible that a new row $r$ inserted at position $p$ to \"push\" some rows that were inserted much earlier if the position of these rows is $\\geq p$. Updating all row positions will be done during peek.\nWe will use $r.p$ to represent the stored position of a given row $r$. Now for peek, we will use \"bucket-sort\" like technique. Create a new array $B$ whose size is $n$, the current number of rows in $M$.", "318" ], [ "This array is actually an array of linked list (like a hash table). Now traverse $M$ backwards, removing each row along the way. When a row $r$ is removed, insert it at the head of list $B[r.p]$. This will empty $M$ and transfer everything to $B$, but rows with different positions are stored in separate buckets. As for rows with the same position, their order in $B$ are preserved. From the example above, $r_i$ and $r_j$ will be stored on the same bucket and $r_j$ will still be in front of $r_i$. Let $i = 0$. Empty $B$ by removing the contents (rows) of each bucket one at a time starting from $B[0]$ up to $B[n-1]$. When a row $r$ is removed from $B$, set $r.p = i$, increment $i$, then insert it to $M$ but this time at the tail. Inserting at the tail of a circular, double linked list also takes $O(1)$ time. Observe that once $B$ is empty all rows have their correct position and are stored in $M$ in order of their position. Now you can start traversing $M$ to peek the row you need. Transferring rows from $M$ to $B$ back and forth takes $O(n)$ time and the actual accessing of a row takes $O(n$) time, thus overall you have $O(n)$ for peek.", "318" ], [ "Imagine that we have an array $A$ of size $n$. Mergesort splits this array into two equal halves and sorts them individually. So in context of the paragraph you have provided, each node corresponds to some chunk of the original array that we want to sort. We divide a node $A[L,R]$ to two nodes $A[L,M]$ and $A[M+1,R]$ with $M = \\frac{L+R}{2}$\nThe splitting of a node $A[L,R]$ into two nodes takes $R-L+1$ time and then merging the two child nodes $A[L,M]$ and $A[M+1,R]$ again takes $A[R-L+1]$ time.", "743" ], [ "Thus for every node, the number of operations the algorithm performs is equal to twice the size of the array corresponding to that node.\nThus we have that on any particular level if we have an array of size $k$, splitting and merging of the array can be done in $k + 2\\times \\frac{k}{2} = 2k$ operations.\nNow note that we keep splitting the array till we have arrays of size $1$ since we can't split them further.\nDraw a binary tree with the root node corresponding to the array $A[1,N]$ and with each node having two children corresponding to its left and right halves and recursively draw the structure for each child till we have arrays of size $1$. Denote each node by the size of the array that it corresponds to. We will get something that looks like this\n(Taken from Khan Academy)\nThis is the recursion tree for merge sort.\nThe computation time spent by the algorithm on each of these nodes is simply two times the size of the array the node corresponds to. Therefore the total running time $S$ of mergesort is just the sum of all the sizes of the arrays that each node in the tree corresponds to i.e. $$S = 2 \\sum_{i=0}^k 2^i\\frac{n}{2^i}$$\n(How did we get this sum? There are $2^i$ nodes of size $\\frac{n}{2^i}$ in the tree and it takes $2k$ time to finish computation on an array of size $k$)\nObserve that when $i=k$, $\\frac{n}{2^k} = 1 \\implies n = 2^k \\implies k = \\lceil{\\log n}\\rceil$ Thus $S$ reduces to $$2 \\sum_{i=0}^{\\lceil{\\log n}\\rceil} n = 2n\\lceil{\\log n}\\rceil = \\mathcal{O}(n\\log n)$$", "743" ], [ "Unfortunately, I am not a latex/markdown guru, either. Let's see if we'll be able to make things work nonetheless.\nThe idea is actually quite simple. Just like in the book, let us assume that the find path consists of s nodes. We disregard the root (because its potential doesn't change at all after the operation) and the node we upon which find_set is called (because it may have rank 0, which means its potential might not change). This leaves us with s-2 nodes.\nNow, consider any node z among the remaining s-2 nodes. As explained on pages 576-577 (I am using the 3rd edition), we have 0 <= level(z) < alpha(n). In other words, the level of z must be between 0 and alpha(n) - 1, inclusive. Indeed, it is the fact that we have a finite number of options for the levels of the aforementioned s-2 nodes that will help us prove the assertion presented by the authors.\nThey say one example is worth a thousand words, so let's do one.", "7" ], [ "Suppose we have 8 nodes between the root and the one upon which find_set was called. Suppose also that alpha(n) turns out to be 4. Here's one possibility for the levels of the nodes, given in the order they appear in the find path:\n2, 0, 1, 3, 2, 3, 1, 0\nThe book claims that there are at most alpha(n) (4 in our case) nodes x for which there doesn't exist a node y later in the path such that level(x) = level(y). Take a good look at the sequence; you'll see that the claim holds for our example.\nNow, the million dollar question. Why? Think about the last alpha(n) nodes. We could assign different levels to each one (as I have done for this example) so that none of them have a complementary node higher up the find path with the same level. However, that is the most we can have; every other node will now have some ancestor with the same level. Long story short, no matter how hard we try, we cannot have more than alpha(n) nodes without an ancestor of equal level; such a scenario would require more options for the level of a node than are available.\nPut it all together, and it is evident that there exists another node with the same level down the line for at least s - alpha(n) - 2 of the s nodes, just like the book claims.\nAs for why the authors have found it unnecessary to provide an explanation for their claim, you are asking the wrong guy.", "743" ], [ "Introduction\nWhile solving google foobar I stumbled upon this problem. I approached the problem with A* along with a few modifications. As this algorithm correctly outlines the core concepts, I would like to go further ahead and add some detailing to this.\nAlgorithm:\nEach node will have the following parameters:\n1. parent: The immediate parent of the node.\n2. position: This is the (x,y) position of the node.\n3. f,g,h: These are the heuristics needed for A* to work.\n4. wall_broken: This is a boolean flag that would account for a broken wall in the path to the node. By default is set to False.\nAfter we set up our pre-requisites, we move into the algorithm.\n1. Create the start and end node.\n2. Initialize the open and closed lists. The open list must contain the start node.\n3. Iterate until we have visited each node.\n1. Take the node with least f from the open list.", "835" ], [ "This is our current node. Remember putting it inside the visited list.\n2. Check whether the current node is the end node. When comparing equality, we will compare the positions of the nodes only. If yes, then hurray! Return the path that has been traced. If no, perform the next step.\n3. Generation of children from the current node.\n+ Check for validity of the position.\n+ Check if the position has a wall. If it does, then we need to check whether the current node has any broken walls in its path (this is where we will need the wall_broken property of the node). We destroy the wall if we have no prior destruction. We make sure to assign the wall_broken property of the child which broke into a wall to True.\n+ We do not generate children if they already have been visited.\n4. Iteration on the children to decide which goes into the open list and which don't.\n* Assign heuristics to each child.\n* Look for a better child in open to replace. Else add it into the open list.\nConclusion\nThis algorithm is a modification of the A*. It conveys the core concept. If you want a detailed walkthrough of the concept with code, I have a gist written in python.", "242" ], [ "Sum of size of distinct set of descendants $d$ distance from a node $u$, over all $u$ and $d$ is $\\mathcal{O}(n\\sqrt{n})$\nLet's consider a rooted tree $T$ of $n$ nodes. For any node $u$ of the tree, define $L(u,d)$ to be the list of descendants of $u$ that are distance $d$ away from $u$. Let $|L(u,d)|$ denote the number of nodes that are present in the list $L(u,d)$.\nProve that the sum of $|L(u,d)|$ over all distinct lists $L(u,d)$ is bounded by $\\mathcal{O}(n\\sqrt{n})$.\nMy work\nConsider all $L(u,d)$ such that the left most node on the level $Level(u) + d$ is some node $v$.", "743" ], [ "The pairs $u, d$ for all such $L(u,d)$ must be distinct and the sum of all $d_i$ will correspond to the number of nodes $x$ in the tree with $Level(x) \\le Level(u) + d$.\nThis is because if some sequence of nodes $v_1, v_2, \\dots v_k$ corresponds to the descendants of some node $u$ at a distance $d$ and the sequence of nodes $v_1, v_2, \\dots v_{k'}$ where $k' > k$ corresponds to the descendants of some node $u'$ at a distance $d+1$, then there must also exist a node $u''$ such that $L(u'', d) = v_{k+1}, v_{k+2}, \\dots v_{k'}$. This would also mean that $u''$ is not in the subtree of $u$ and thus there are at least $d$ distinct nodes in the subtree of $u''$ upto a distance $d$ from $u''$.\nIf the distinct distances are $d_1, d_2, \\dots d_k$ then, $n \\ge \\sum_{i}d_i \\ge \\sum_{i=1}^{k}i \\ge \\frac{k(k+1)}{2}$. =\n$\\implies k \\le \\sqrt{n}$\nAfter this I tried to show that there can be only $\\mathcal{O}(\\sqrt{n})$ distinct lists $L(u,d)$ so that I can then trivially obtain the upper-boud of $n\\sqrt{n}$ but I could not make any more useful observations.\nThis link claims that such an upper bound does exist but has not provided the proof.\nAny ideas how we might proceed to prove this?", "532" ] ]

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[ [ "Present Surprise Cake\nIntroduction: Present Surprise Cake\nGet into the holiday spirit by baking yourself a gift this season! We created this cake in our foods class at Wachusett Regional High School as part of a challenge to create edible art. Everything is made 100% from scratch. We made a surprise cake with a simplistic disguise as a Christmas gift box, filled with Christmas m&ms and topped with a fondant ribbon.\nSupplies\n- Mixing bowl: To mix the melted marshmallows and powdered sugar together\n- Microwave: To melt the marshmallows that will be used to make the fondant\n- Mixer: To mix ingredients together to make the cake batter and buttercream\n- Rolling pin: to roll out the fondant\n- Cake pan: to put the cake batter in so the cake can be baked\n- Oven: to bake the cake\n- Measuring cups: This will be used to measure out the ingredients needed to make the cake batter, fondant, and buttercream\n- Knife: To level out the cake after it has been cooked, to add the buttercream to the cake, and to cut the fondant into its desired shape\n- Spatula: to fold the sprinkles into the cake\nIngredients:\nFunfetti Cake:\n- 9 Tablespoons unsalted butter softened\n- 3 cups granulated sugar\n- 1 cup vegetable oil\n- 4 teaspoons vanilla extract\n- 4 cups+ 2 Tbsp all-purpose flour (all of the flour goes into the cake batter, you will also need additional flour for preparing the cake pan)\n- 4 ½ teaspoons baking powder\n- 1 ½ teaspoons salt\n- 1 ½ cup milk\n- 9 egg whites\n- ½ cup sprinkles\nButtercream:\n- 2 cups unsalted butter\n- ¼ teaspoon salt\n- 6 cups powdered sugar\n- 2 teaspoons vanilla extract\nFondant:\n- 4 cups powdered sugar\n- 4 cups mini marshmallows\n- 2 tablespoons water\n- Red food coloring\nStep 1: Pre-Heat Oven\nPreheat the oven to 350F and prepare 3 square cake pans by generously greasing and flouring.\nStep 2: Prepare Cake Batter\n1. In a stand mixer, beat butter on medium-low speed until creamy.\n2. Add sugar and oil and beat until all ingredients are well-combined and creamy.\n3. Scrape down the sides and bottom of the bowl and then stir in your vanilla.\n4. In a separate bowl, whisk together your flour, baking powder, and salt.\n5. Measure out milk. With the mixer on medium speed, gradually alternate between adding the flour mixture and the milk to the butter mixture, starting and ending with the flour mixture. Stir until each one is almost completely combined before adding the next. Pause occasionally to scrape down sides on the bowls.\n6. In a separate bowl, combine your egg whites and, with a hand-mixer on high-speed, beat until stiff peaks form.\n7. Using a spatula, gently fold your egg whites and sprinkles into your batter. Take care to scrape the sides and bottom of the bowl so that ingredients are well-combined, and take care not to over-mix.\nStep 3: Bake Cakes\n1.", "305" ], [ "Evenly divide cake batter into cake pans.\n2. Bake at 350F for 35-40 minutes, or until a toothpick inserted in the center of each cake layer comes out clean or with a few crumbs (should not be wet). For best results, rotate your cake pans halfway through baking to ensure even baking. Cakes should be a light golden brown when done baking.\n3. Remove cakes from the oven and let them cool for 15 minutes. Run a spatula around the inside rim of each pan and place each onto a cooling rack.\nStep 4: Prepare Frosting\n1. In a stand mixer, beat butter on medium-speed until creamy. Add salt and begin beating again for about 20 seconds.\n2. Gradually, about 1 cup at a time, add powdered sugar, waiting until each cup is completely mixed before adding the next cup.\n3.Tablespoon at a time, add the heavy cream on medium-high speed, waiting until each addition is well-combined before adding the next 2 Tbsp.\n4. Add vanilla extract and mix on medium-high speed for 30 seconds.\n5. Add green food coloring to the buttercream mixture and mix on medium-high speed until fully combined.\nStep 5: Assemble Cake\n1. Level all 3 cakes on the top using a knife shaving off about ½ a cm on each cake.\n2. Cut a square hole into the middle of two of the square cakes. Leaving about 3 inches off from the edge of the cake.", "195" ], [ "Festive Cake Pops\nIntroduction: Festive Cake Pops\nAs Christmas time is coming around I thought I should make a fun treat with festive colors. I love the Starbucks cake pops but it is so much more expensive to buy there than to make at home. These cake pops are simple, delicious, and fully customizable whether you use a store bought cake and icing or make it homemade.\nSupplies\nIngredients -\n-1 2/3 cups all purpose flour\n-1/4 teaspoon baking soda\n-1/2 teaspoon baking powder\n-1/2 teaspoon salt\n-1 cup whole milk whole milk\n-7 tablespoons unsalted butter\n-1 cup granulated sugar\n-3 teaspoons vanilla\n-1 egg\n-1 3/4 cups powder sugar\n-White chocolate candy melts\n-sprinkles\n-cake pop sticks\nTools -\n-oven (to bake the cake)\n-fridge/freezer (to chill the cake pops)\n-Microwave safe bowl (to melt the chocolate)\n-11x7 cake pan (to bake the cake in)\n-whisk (to mix the ingredients)\n-stand mixer (to mix the ingredients)\n-toothpick (to check the cake)\n-parchment paper (to let cake pops rest)\nStep 1: Make the Cake (skip If Using a Box Cake)\n1. Preheat oven to 350 degrees Fahrenheit and grease an 11x7 cake pan.\n2. Whisk flour, baking powder, baking soda, and salt in a medium bowl and set aside.\n3. In a stand mixer with a paddle or whisk attachment, beat butter and sugar together until creamed - about 2 minutes.\n4. Add egg and vanilla extract and beat on high speed until combined. Scrape down the bottom and sides of the bowl if needed.\n5. With mixer on low speed, add dry ingredients and milk to wet ingredients.\n6. Pour batter into a greased pan and bake for 30-36 minutes and until a toothpick comes out clean.\n7. Let the cake cool completely in the pan set on a wire rack.\nStep 2: Make the Frosting (skip If Using Store Bought)\n1. With a stand mixer and paddle attachment, beat butter on medium speed until creamy - about two minutes.\n2.", "305" ], [ "Add powdered sugar, milk, and vanilla extract with the mixer running on low.\n3. Increase to a high speed and beat for 3 minutes.\nStep 3: Crumble and Form the Cake Balls\n1. Crumble cooled cake into a bowl on top of the frosting and make sure there are no large lumps.\n2. Turn the mixture on low and beat frosting and cake crumbs together.\n3. Measure 1 tablespoon of cake mixture and roll into a ball.\n4. Place balls on a lined baking sheet and either refrigerate for at least 2 hours or freeze for at least 1 hour.\n5. Re-roll the chilled balls to smooth out.\nStep 4: Melt Chocolate and Coat the Cake Pops\n1. Melt chocolate in a two cup liquid measuring cup in the microwave.\n2. Take 2-3 cake balls from the fridge at a time.\n3. Dip a stick about 1/2 inch into the coating and insert into the center of the cake ball, only pushing halfway through.\n4. Dip cake pop into coating making sure it covers the base where the stick is.\nStep 5: Decorate the Cake Pops\nYou can decorate these cake pops with whatever you want. Some things you can use are sprinkles, chocolate chips, m&ms, etc. The coating hardens fast so make sure you do everything quickly.", "195" ], [ "Geode Sugar Cookies\nIntroduction: Geode Sugar Cookies\nI love making beautiful desserts that taste as good as they look. Geode cakes have been a popular trend for weddings and special events, so I decided to try the same concept to make cookies. These are relatively simple to make, yet stunning and sure to impress your friends. So let's get started!\nSupplies\nCookies\n* 1 cup butter, softened\n* 4 ounces cream cheese, softened\n* 1 cup sugar\n* 1 egg yolk\n* 1 teaspoon vanilla\n* 1/2 teaspoon salt\n* 2 3/4 cups flour\nIcing\n* 2 cups powdered sugar\n* 2 tablespoons light corn syrup\n* 3 - 4 tablespoons milk\n* 1 teaspoon vanilla\nDecorations\n* rock candy\n* gel food color\n* gold luster dust\nTools\n* mixing bowls\n* spatula\n* electric mixer\n* rolling pin\n* cookie sheets\n* parchment paper\n* cookie cutters\n* food safe paint brush\nNOTE: If you have a favorite sugar cookie recipe, you can use it! This recipe makes a soft cookie, but any sugar cookie will work fine. If you prefer Royal Icing, that works too!\nStep 1: Beat Butter and Cream Cheese\nIn the bowl of a stand mixer, beat butter and cream cheese until creamy, about 2 minutes on medium speed.\nStep 2: Add Sugar, Egg, Vanilla and Salt\nAdd sugar and beat until mixture is fluffy and pale in color, about 3 minutes on medium speed. Add egg, vanilla and salt and mix until combined.\nStep 3: Add Flour, Wrap and Chill\nAdd flour and mix on low until just combined. Wrap dough in plastic and chill at least 30 minutes.\nStep 4: Roll Out Dough, Cut Out Cookies and Bake\nPreheat oven to 350 degrees Fahrenheit. Roll out dough between 2 pieces of waxed or parchment paper. Cut out shapes. I used a 3 inch round cookie cutter, but you can use any shape. Place on parchment-lined baking sheet and bake for 10 - 12 minutes. Remove and cool on wire rack.", "305" ], [ "This recipe makes about 16 cookies (3 inch round).\nStep 5: Make Marbled Icing\nMix together powdered sugar, corn syrup, vanilla and 3 tablespoons of milk. Icing should have the consistency of honey. If it is too thick, add more milk.\nSeparate into individual bowls and color with food coloring. I used black and gray for these cookies. You only need a small amount of each color. Now, the fun part! drizzle a little of the colored icing on top of the bowl of white icing and stir with a toothpick to create a marbled effect.\nStep 6: Dip Cookies in Icing and Add Rock Candy\nDip the tops of the cookies in the icing and let excess drip back into the bowl. Place on wire rack and immediately sprinkle rock candy on top. Let dry completely.\nStep 7: Paint With Food Coloring and Luster Dust\nThin the food coloring with water to make a liquid. Paint the rock candy to resemble a geode. I kept the color lighter around the edges and darker in the center. Next, mix the gold luster dust with a little vodka to make a liquid. Paint it around the edge of the rock candy geode.\nThat's it! Enjoy your beautiful & delicious geode cookies!!", "122" ], [ "Decorated Bluebird and Goldfinch Sugar Cookies\nIntroduction: Decorated Bluebird and Goldfinch Sugar Cookies\nCelebrate Spring (or any time) with these delicious sugar cookie birds! In this Instructable, I will show you how to make these cute bluebirds and goldfinches. The decorating possibilities are endless, so use this as inspiration and unleash your creativity to make any kind of birds you like.\nStep 1: Ingredients and Tools\nIngredients:\n* 3 cups all purpose flour\n* 1/2 teaspoon salt\n* 1 cup (2 sticks) unsalted butter\n* 1 cup granulated sugar\n* 1 large egg\n* 2 teaspoons vanilla\n* Royal Icing\nTools:\n* Bowls\n* Spatula\n* Whisk\n* Electric mixer\n* Rolling pin\n* Parchment paper\n* Cookie sheet\n* Cookie cutters\n* Piping bags and tips\nStep 2: Mix Dry Ingredients\nCombine flour and salt in a medium bowl with a whisk.\nStep 3: Cream Butter and Sugar\nCream butter and sugar in a mixer with paddle attachment until pale and fluffy, about 5 minutes on medium speed.\nStep 4: Add Egg, Vanilla and Flour\nBeat in egg and vanilla on medium speed until just combined. Add flour mixture and stir on low until combined.\nStep 5: Wrap and Chill\nTurn out on counter and form into a flattened disc about 1/2 inch thick. Wrap with plastic and refrigerate at least 30 minutes.\nStep 6: Roll Out Dough, Cut Out and Bake\nPreheat oven to 325 degrees Fahrenheit. Roll out dough between two pieces of parchment paper to a thickness of about 1/4 inch. Cut out birds. Place on cookie sheet lined with parchment paper and bake 12-14 minutes until edges begin to turn golden brown.", "305" ], [ "Remove from oven and cook completely.\nStep 7: Prepare Piping Bags and Decorate Goldfinches\nColor flood consistency Royal Icing in the colors desired. I used bright yellow and black for the goldfinches. Pipe the yellow and let dry at least an hour. Then pipe black head, tail, wings and eyes. Keep it simple or get as creative as you like!\nStep 8: Decorate Bluebirds\nTo make bluebirds, start by piping a white belly. Let dry at least an hour and then pipe the blue body and head. Let dry again for at least an hour. Then add the wing, beak and eye.\nStep 9: Share and Eat!", "706" ], [ "How to Make Vanilla Meringue Cookies\nIntroduction: How to Make Vanilla Meringue Cookies\nFor this recipe, we will be making vanilla meringue cookies. The following tools and ingredients will be needed:\nTools:\n* Measuring cups & spoons\n* A mixer\n* A large mixing bowl\n* A baking pan\n* Parchment paper\n* Optional: piping bags\nIngredients:\n* 1/4 cup of meringue powder\n* 1/2 cup of water\n* 1-1/3 cup of granulated sugar\n* 2 teaspoons of vanilla extract\n* Optional:\n+ Food coloring\n+ Sprinkles\n+ Other extract flavorings\nStep 1: Prepare Your Materials\nThe first steps to making your cookies is to prepare. Preheat your oven and clean all of your tools. Oil is a contributing factor to failing meringue cookies so be sure to thoroughly wipe down your bowl and other tools to get rid of oil from previous cooking endeavours and from your hands.\n* Heat your oven to 250 degrees Fahrenheit.\n* Clean all of your tools free of dust and oil.\nStep 2: Putting the Ingredients Together\nThe next step is to combine all of your ingredients into the bowl. Start first by sifting the dry ingredients into the bowl and then add your wet ingredients. By sifting the dry ingredients you get rid of unwanted clumps that would ruin your mixture.\n* Sift 1-1/3 cups of sugar into the cleaned mixing bowl\n* Sift the 1/4 cup of meringue powder into the bowl with the sugar\n* Add 1/2 cup of room temperature water to the dry ingredients\n* Add the 2 teaspoons of vanilla extract to your mixture.\nTip #1: You can substitute the vanilla extract for other extract flavorings of your choice.\nTip #2: For more fun, you can add a few drops of food coloring to tint your cookies.\nStep 3: Mixing\nOnce all of your ingredients are added to the bowl you can now start mixing. Start first by setting your mixer on low to prevent the dry ingredients from making a mess. When all the ingredients start to form a wet mixture, increase the speed of your mixer to high. Continue mixing on high until your mixture starts to form stiff peaks that do not lose their shape like in the picture.\nStep 4: Assembly\nOnce your mixture is ready, line a baking pan with parchment paper.", "195" ], [ "The parchment paper will stop the cookies from sticking to the pan and prevent breaking when trying to remove them after they are done baking. Spoon the mixture into a piping bag with the end cut off, leave a nickel-sized hole at the end so the mixture flows out easily. Using circular motions, pipe the mixture onto the lined baking sheet, gradually make smaller circular motions to create the typical meringue cookie shape. Ensure to leave space between each individual cookie so that they don't stick to each other when baking.\nTip #1: If you don't have a piping bag you can use large spoons to directly place your meringue cookies onto the pan.\nTip #2: You can add sprinkles on top of the piped cookies before baking\nStep 5: Baking\nOnce you have assembled your cookies it's time to bake. Place your cookies on the middle rack of your 250 degrees Fahrenheit preheated oven. Place a wooden spoon in between the door of the oven to crack it open. This will ensure that moisture does not build up and helps quicken the drying time. Depending on the size of your cookies bake them for 1 to 2-1/2 hours until the outsides feel dry and firm. Once the cookies are done baking turn off the oven and let them cool down completely while still inside. Once the cookies are at room temperature remove them from the baking sheet.\nStep 6: Enjoy\nYou have now cooked your batch of meringue cookies! Enjoy them and store them in an air-tight container for lasting freshness.", "122" ], [ "Fruit & Cheesecake Spread Sandwich\nIntroduction: Fruit & Cheesecake Spread Sandwich\nThis sweet and refreshing sandwich will satisfy your sweet tooth without leaving you feeling like you ate a dense dessert. I love desserts and figured if there are dessert pizzas, there should be a dessert sandwich. I was inspired by Japanese desserts because they're sugary but light, so I went to the Japanese Market to get some Japanese bread. It's sweet and fluffier than typical bread which was perfect for this sandwich. The delicious cheesecake spread complements the fruit and only requires 4 ingredients. For this recipe, I put strawberries and raspberries on my sandwich, but you can use any of your favorite fruits.\nSupplies\nTo make this sandwich, you will need:\n2 slices of bread (I used Japanese bread)\nFruit(s) of choice\n1/4 cup butter, softened\n4oz.", "763" ], [ "cream cheese, softened\n1/2 cup powdered sugar\n1tsp. vanilla extract\nYou will also need:\n1 medium sized bowl\nHand mixer or spatula\nMeasuring spoon\nMeasuring cup\nKnife to cut fruit and spread cream cheese mixture\nStep 1: Beat Cream Cheese & Butter\nBegin by combining the cream cheese and butter with a hand mixer or spatula on low speed. Make sure cream cheese and butter are softened so the mixture is smooth.\nStep 2: Add in Powdered Sugar & Vanilla\nAdd the powdered sugar and vanilla extract to the cream cheese mixture and mix until fully combined. If there is extra cheesecake spread, you can use it as a yummy dip for fruit or crackers.\nStep 3: Preparing Fruit\nWash and cut your fruit so it is ready to go onto the bread. I used strawberries and raspberries, but any fruits would work. Make sure that when slicing your fruit it is able to lay flat on the bread.\nStep 4: Making the Sandwich\nArrange your sliced fruit onto one piece of bread and put the cheesecake spread on the other. Place this piece of bread onto the fruit.\nStep 5: Finishing the Sandwich\nFinally, you can cut your sandwich in half and enjoy your dessert sandwich! This simple treat is easy to make but tastes delicious.", "851" ], [ "Lemon Pie With Meringue Roses\nIntroduction: Lemon Pie With Meringue Roses\nLooking for a fabulous Spring dessert? Try this reinvention of a classic lemon meringue pie! It's just the right combination of sweet & tart, with fresh lemons and a coconut shortbread crust. I love the combination of lemon and coconut. Add to that a wreath of delicious vanilla meringue roses and you have a real showstopper!\nI've been decorating cakes with buttercream flowers for quite awhile when it occurred to me - why should cakes have all the fun? Why not use the same techniques to level up my pie game? This lovely decor is simply meringue that has been colored, piped and baked just like French meringue cookies. Crispy on the outside and chewy and marshmallow-y on the inside. The colorful meringue wreath is then placed atop a lemon pie or tart and voila!!!\nSupplies\nCoconut Shortbread Crust:\n* 1 1/4 cups flour\n* 1/2 cup shredded sweetened coconut\n* 1/2 teaspoon salt\n* 1/2 cup butter, cut into small c\n* 1/3 cup sugar\n* 1 egg\n* 1 teaspoon vanilla\nLemon Filling:\n* 1 1/2 cup sugar\n* 1/4 cup lemon zest\n* 1/2 cup butter, room temperature\n* 2 eggs + 2 egg yolks\n* 3/4 cup lemon juice\n* 1/4 teaspoon salt\n* 1/2 cup heavy whipping cream\nMeringue Roses:\n* 4 egg whites\n* 1 cup sugar\n* 1/2 teaspoon cream of tartar\n* 1 teaspoon vanilla\n* food coloring\nStep 1: Make the Coconut Shortbread Crust\nCombine the flour, coconut, sugar and salt in a food processor and pulse to combine. Add the butter and pulse until the mixture resembles coarse crumbs, about 10 - 15 pulses. Add the egg and vanilla and pulse until the dough begins to come together, about 15 more pulses. Do not process to the point where a large ball of dough forms.\nTurn out on counter and form into a disc. Wrap in plastic and refrigerate at least 15 minutes. Note: you can make this ahead and store in refrigerator up to 3 days or freeze up to a month.\nStep 2: Roll Out and Bake Crust\nRemove dough and roll out to a 12 inch circle between 2 pieces of waxed paper. Place into a 10 inch tart pan and trim to fit. Cover with plastic wrap and put in freezer at least 15 minutes.\nPreheat oven to 350 degrees Fahrenheit. Bake for 20 - 25 minutes until crust is golden brown. Cool.\nStep 3: Make Lemon Filling\nZest and juice the lemons. Put the sugar and zest in a food processor and pulse until zest is finely minced. Cream the butter and sugar in a mixer. Add eggs one at a time and mix to combine. Add lemon juice and salt and mix. Pour the mixture into a medium saucepan and cook over medium low heat until thickened stirring constantly, about 10 minutes.", "763" ], [ "Mixture should get to about 170 degrees Fahrenheit and coat the back of a spoon when done. Remove from heat and refrigerate to cool.\nWhip the cream. Fold into lemon mixture and pour into pie crust.\nStep 4: Make the Meringue Roses\nPreheat oven to 225 degrees Fahrenheit. Draw a circle on a sheet of parchment paper as a piping guide, approximately 8 inches in diameter. Turn parchment paper upside down and place on a baking sheet.\nIn a stand mixer with whisk attachment, beat egg whites on medium speed until frothy. Add cream of tartar. Increase speed to medium high and beat until soft peaks form. Add sugar, slowly pouring about 2 tablespoons at a time, beating until sugar is dissolved and stiff peaks form. Beat in vanilla.\nSeparate into smaller bowl and color as desired. I used lavender, pink, yellow and green. Put each into a piping bag with tip. I used the Wilton 1M tip for the roses and the Wilton 68 tip for leaves.\nTo pipe a rose, begin at the center with the piping bag straight up (perpendicular to the parchment surface.) Squeeze the piping bag until the meringue begins to release like a small flower. Now move the bag around the center to make a swirl. Continue to rotate around until you get the size of rose that you like. Slowly release pressure at the end of the swirl. There are lots of videos available online that demonstrate this technique.\nContinue piping roses in different colors until you fill in the circle. Add leaves as desired. Have fun & be creative!!\nNext, bake for 1 hour. Then turn oven off and let meringues stand in for an additional hour. Do not open the oven.\nStep 5: Decorate and Enjoy!", "491" ], [ "Sweet Potato Casserole in a Pumpkin Bowl\nIntroduction: Sweet Potato Casserole in a Pumpkin Bowl\nI will be making a delicious sweet potato casserole in a pumpkin bowl. This is a perfect treat to make for the holidays and fall time! On top of that, it looks really pretty as well. This is one of my favorite things to eat with a cute touch.\nStep 1: Ingredients\nThis can serve for 4!\n* 4 bowl sized pie pumpkins\n* 4 cups of peeled and cubed sweet potato\n* 1/4 cup white sugar\n* 1 egg (beaten)\n* 1/4 teaspoon salt\n* 2 tablespoons butter, softened\n* 1/4 cup milk\n* 1/4 teaspoon vanilla extract\n* 1/4 cup packed brown sugar\n* 1/4 cup all-purpose flour\n* 2 tablespoons butter softened\n* 1/4 cup chopped pecans\n* (optional) marshmallows\n* (optional) 1/8 teaspoon cinnamon + all spice\nStep 2: Preparing the Pumpkins\nWash pumpkins.\nHeat pumpkins in the microwave for about 7-8 minutes and periodically check the pumpkins as microwave temperatures can vary. This is so that the pumpkins are easier to cut! Using a very sharp knife, carefully cut around 1/2 to 1/3 of the top off and scoop out the insides to create bowls.\nPlace pumpkins in a 9 x 13 inch baking dish with about 1/2 inch of water. Place in the oven and bake for 40 minutes at 350 degrees Fahrenheit or until the pumpkins are tender. While the pumpkins are baking, start making the casserole!\nStep 3: Making the Casserole\nPut the cubed sweet potatoes in a medium saucepan with water to cover. Boil at medium high heat for about 15 minutes or until tender. Once cooked, drain the water and mash in a separate large bowl.", "2" ], [ "After the potatoes have been mashed, add the white sugar, egg, salt, butter (2 tablespoons), milk, and vanilla extract. Mix with a beater until smooth. Add the cinnamon and all spice in now if you choose to include it!\nStep 4: Make Casserole Toppings\nIn a medium bowl, mix your brown sugar and flour. Add in the butter and then the chopped pecans. Mix until coarse.\nStep 5: Fill Pumpkins and Bake\nTake the baked pumpkins out of the oven and add the sweet potato mixture first. Leave room for the topping! Add the brown sugar, flour, butter, and pecan mixture on top of the sweet potato mix. Add marshmallows if you would like!\nPreheat oven again to 350 degrees Fahrenheit. Fill the 9 x 13 baking dish with a little bit of water. Place in oven and bake for 30 minutes.\nStep 6: Eat and Enjoy!\nAfter they have been baked, let cool and enjoy! The good news is is that the pumpkin is edible as well ;)", "195" ] ]

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[ [ "Kenyan TV Networks Censored for Airing Symbolic ‘Swearing In’ of Opposition Leader <PERSON> · Global Voices\n<PERSON> speaks at the 2013 World Economic Forum. Photo by WEF via Flickr (CC BY-SA 2.0)\nWhen Kenyan opposition leader <PERSON> was symbolically — if not legally — sworn in as the “people's president” on January 30, three major broadcasting networks were unplugged by the Government of Kenya.\n<PERSON> was sworn in for a second term as president on November 28, 2017 after winning a controversial re-run election, which was held in October 2017 after the country's Supreme Court annulled the results of the initial August 2017 vote, having found “irregularities and illegalities”. <PERSON> did not participate in re-run, arguing that systemic flaws that produced these irregularities had not been addressed. The elections were marked with protests, multiple incidents of violence and destruction of property.\nAfter months of uncertainty, incumbent president <PERSON> remains in power. But supporters of <PERSON> remain committed to his campaign and cause.\nOn January 30, 2018, thousands of Kenyans flocked to the famous Uhuru Park to witness a symbolic swearing-in ceremony for <PERSON> of the National Super Alliance (NASA). The majority of attendees were mainly people from Western, Nyanza, Coast and Eastern parts of Kenya where NASA enjoys sizable support.\n<PERSON> being “sworn in” as the Kenya's People's President [Screen shot taken on February 1, 2018]\nSome Kenyans did not go to work and decided they were going to watch this historic event from the comfort and safety of their homes. To their disappointment, the government decided to disconnect all the major broadcasting stations in the country including KTN News, Citizen TV and Inooro TV (both owned by Royal Media Services) and NTV, preventing them from effectively airing live coverage of the event.\nAccording to Kenya's Attorney general, the mock ceremony was “treasonous” and therefore, in their view, had no place on national television.\nThe Committee to Protect Journalists reported that President <PERSON> and other executive staff “summoned media managers and editors on January 26 and threatened to shut their stations down and revoke their licenses” if they proceeded with the broadcast.\nThis raised a loud uproar from civil society organizations and Kenyans in general from all walks of life and different political affiliations. The freedom of media is well-anchored in Kenya’s 2010 constitution, but this did not stop the <PERSON> government from denying Kenyans access to information\n‘People's president’ or ‘treasonous’ swearing in?\nWhile <PERSON> indeed does not hold the office of the President in Kenya, the ceremony at hand was more than just a show of support for <PERSON> and the NASA.\nIt came as the result of the People's Assemblies Bill, a motion tabled in all opposition-controlled counties that legalized “the formation of the people's assemblies in the devolved units”. The People’s Assemblies bill has been passed by at least 20 county governments out of 47.\nAccording to the People’s Assemblies bill, the power is vested in the people and their assemblies will have the power to recognize a leader of their choice.", "424" ], [ "Though this move by a select number of counties was perceived to be unconstitutional, it received substantial national support. The law also allows anybody of the capacity of a high court judge to administer the oath.\nMost of all I thank the good Lord, my family and all those who have undertaken this journey with us. We have arrived in Canaan; thank you for staying the course with us. <PERSON>. pic.twitter.com/6gdZBfxVAv\n— <PERSON> (@RailaOdinga) January 30, 2018\nThe swearing in ceremony of Mr. <PERSON> was meant to be held in 2017, but it was delayed due to a deep divide between <PERSON> and his core principals.\nIn the January 30 swearing-in ceremony, Mr. <PERSON>’s running mate, <PERSON> and other NASA core principles, <PERSON> and <PERSON>, did not turn up to the historic event. This kept <PERSON> waiting for too long, and infuriated the highly-charged crowd.\nWith advice from his key supporters, <PERSON> decided to take an oath of office as the people’s president in the absence of his running mate <PERSON> and other NASA principles. <PERSON> claimed they did not turn up at the Uhuru Park for the swearing in ceremony because their security guards were withdrawn by the state:\nI was left alone.", "1017" ], [ "Is Mandarin Chinese the language of East Africa’s future? · Global Voices\n<PERSON>, Chinese Ambassador to Djibouti, congratulates a language class student during a graduation ceremony at the Institute of Diplomatic Studies in Djibouti, June 14, 2015. Some of the graduating students spent the last nine months studying Mandarin. Photo by US Air Force Sgt. <PERSON>/Combined Joint Task Force: Horn of Africa.\nThe introduction of the Mandarin Chinese language to East African school curricula signals China’s growing influence in Africa as a global superpower.\nIn January, Kenya’s Curriculum Development Institute announced that in 2020, Mandarin will become part of Kenya’s school curriculum as an optional subject in elementary schools. Kenya is the latest East African nation to follow the Chinese-language trend in schools after Tanzania, Rwanda, Uganda, Zimbabwe and South Africa, among others.\nAs China strengthens its already robust trade and infrastructural ties with Africa, Chinese-government funded Confucius Institutes (CIs) and Confucius Classrooms (CCs) are on the rise in East Africa. As of 2018, China has established 27 CCs and at least 51 CIs all over Africa.\nChina has sponsored CIs since 2004 and hundreds have also been established in the United States, Australia, and Canada.\nA simple map of all the Confucius Institutes on the African Continent. For interest there are 51 in total; South Africa has 5, while Kenya has 4. Map made using @cmapit Thanks to @xniyi pic.twitter.com/QGWmBuXuVS\n— <PERSON> (@QHaach) July 1, 2019\nEast African leaders have generally supported the idea that becoming familiar with Chinese languages and culture improves job competitiveness and facilitates better business relations with China.\nUganda, however, is the only East African country that has added Mandarin as a compulsory subject. Instead of contracting out Chinese teachers, Uganda's Ministry of Education Uganda will offer a 9-month program to train 100 local secondary teachers how to read, speak and write Mandarin at Luyanzi College, who can then teach the language in other secondary school classrooms.\nIn 2016, Luyanzi became the first secondary school in Uganda to teach Mandarin.", "424" ], [ "Ugandan <PERSON> and his Chinese wife of 20 years, <PERSON>, co-own and manage Luyanzi College, a private school. <PERSON>, who has also served as chairperson of the Uganda-China Friendship Association, believes it is necessary to learn Mandarin in order to enjoy the benefits China has to offer.\nYet, Ugandan-Chinese relations have also been strained due to complaints of ongoing, unfair trade and labor practices.\nTanzanian President <PERSON> announced in May 2019 that Mandarin has been added to the national Certificate of Secondary Education Exams (CSEE) and students will be able to sit a Mandarin language exam. Just like Uganda, local teachers are receiving training to become adept at Mandarin and teach it in secondary schools.\nIn early July 2019, the Muslim University of Morogoro, in eastern Tanzania, launched a CI Chinese language center. At the inauguration, <PERSON>, deputy permanent secretary of the country's Education Ministry, informed the audience that Marangu Teachers College in Kilimanjaro, northern Tanzania, may also offer Mandarin as a major course. Ongoing negotiations between Tanzania and China could lead to a Mandarin program at Marangu Teachers College that will enable teachers to learn Mandarin similar to Swahili and English degree programs, like those offered at the University of Dar es Salaam and the University of Dodoma, who currently offer a Mandarin degree.\nLearning Chinese language has become a trend in Tanzania in recent years. The picture shows a Tanzanian Chinese language teacher giving guidance to students on learning Chinese language at the Confucius Institute at the University of Dar es Salaamhttps://t.co/4kKTEds5VY pic.twitter.com/azywvNk2od\n— Confucius Institute Online (@chinese_cio) August 2, 2018\nRwanda also recognizes the importance of CIs and CCs in their bilateral relationship with China. Last month, Rwanda hosted the 12th round of “Chinese Bridge,” a Chinese language proficiency competition organized for secondary students. Students from secondary schools throughout Rwanda participated.\nSwahili in China\nChina's relationship with East Africa goes back thousands of years and at times, China has also recognized the importance of learning Swahili as part of its ongoing trade and business relationship. In East Africa, 144 million speak Swahili, a Bantu language that originated along the Swahili Coast as a trade language between Arabs and East Africans.", "424" ], [ "Intrigue and Drama as Malawians Await Election Results · Global Voices\nIn some polling centres in Malawi, lines were so long people couldn't see ahead. Photo by <PERSON>. Used with permission.\nIn a bizarre twist for a country in Sub-Saharan Africa, a governing party is accusing an opposition party of having rigged the election.\nUnofficial results in Malawi's elections for president, members of parliament and ward councillors show the incumbent President Dr. <PERSON>, Malawi's and southern Africa's first female president, losing by wide margins and two opposition candidates neck and neck in the running.\nMalawians flocked to polling centres across the country on Tuesday, 20 May, 2014 for the vote. In much of the country voting went on smoothly, but in a number of centres things did not go as planned. In some centres people lined up from 4 a.m. and waited into the afternoon without voting. Anger spilled over into rage, with one centre being set on fire and cast ballots being destroyed in others.\nPeople had hoped that by Thursday, 22 May they would know who had won the elections, but things have taken a dramatic turn.\nA polling centre in Malawi burns. Photo by <PERSON>. Used with permission.\nAs results started trickling in on Tuesday night, <PERSON> took an early lead and Malawian social media went into overdrive. There was an overwhelming sense that he would win the election, even with only 23 percent of the votes counted. There were calls for <PERSON> to concede defeat and for the Malawi Electoral Commission to declare <PERSON> the winner.", "830" ], [ "Pundits started propounding opinions as to why <PERSON> had won and the other three had respectively lost.\n<PERSON> is the younger brother of late President <PERSON> who died suddenly on 5 April, 2012, in his third year of his second five-year term. <PERSON>, his vice president, had fallen out with <PERSON> Democratic Progressive Party and had formed her own party, the People's Party. After initial attempts by <PERSON> inner circle to subvert the constitution and make his brother <PERSON> the president, <PERSON> was sworn in and became Malawi's forth president, finishing the remaining two years from <PERSON> term.\n<PERSON>'s two years has been characterised by scandals, culminating in the uncovering of massive fraud dubbed “cashgate” that reached all the way to her office. A much-awaited opinion poll by Afrobarometer showed <PERSON> leading, followed by Malawi Congress Party candidate Dr. <PERSON>, and <PERSON> coming a distant third.\nOn Thursday morning, <PERSON> called the press to her official residence Kamuzu Palace where she issued a statement but did not take questions from the media. Blogger <PERSON> posted the statement on his blog. In the president's own words:\nIt has come to my attention that there some serious irregularities in the counting and announcement of results in some parts of the country and the People’s Party has presented specific details of these irregularities to the Malawi Electoral Commission\nShe alluded to fears that the electoral commission's communication system had been tampered with. She listed five irregularities, one of which was:\nUsing information technology to block communication devices of some monitors, and thereby limiting the monitors’ ability to effectively carry out their duties.\nTweeting the briefing was journalist <PERSON>, who reported the president's rigging allegation:\nPres <PERSON> says her party has evidence that election has been rigged and this has been submitted to Mec #Malawivote2014\n— <PERSON> (@suzgokhunga) May 22, 2014\nThe president repeated the allegation in a BBC Focus on Africa interview on Thursday night, putting the blame unequivocally at the electoral commission. The People's Party, of which Dr. <PERSON> is the leader, sought a court injunction to stop Malawi Broadcasting Corporation TV and Zodiak Broadcasting Station from announcing incoming election results from polling centres. The High Court rejected the application, according to a Nyasa Times report.\nIn another press conference later in the day, the Malawi Electoral Commission rejected claims that the computer system could have been hacked into. The Nation newspaper tweeted the press conference and quoted the MEC Chair Justice <PERSON> as saying:\n<PERSON>: “The issue of hacking, we are hearing it from the PP. Its not true, this allegation is not true”.", "830" ], [ "Recent troubles rock the historical Kano Kingdom in northern Nigeria · Global Voices\nThe Emir of Kano, <PERSON>, at Durbar Festival celebrating Eid in June 2018, Kano, Nigeria. Photo by <PERSON> via Wikimedia: CC BY-SA 4.0.\nThe Kingdom of Kano in northern Nigeria is in trouble.\nGovernor <PERSON> of Kano State in northwestern Nigeria, has decided to split Kano Emirate into five distinct territories, breaking up a kingdom that has existed before the age of governors for nearly 1,000 years.\nDating back to the year 999 as one of Nigeria’s largest kingdoms, Kano played a central role in trans-Sahara commercial routes. Kano is home to a remarkable museum that holds ancient relics in a prominent palace, and Nigerians often gather for festivals and exhibitions.\n<PERSON>’s decision to split this ancient kingdom under his governance is tied to a political tug-of-war between himself, Kano’s former governor, <PERSON> and the current king, 57-year-old Emir <PERSON> , the 58th Emir (King) to date — appointed by <PERSON> before his term ended.\nOnce political allies, <PERSON> and <PERSON> became rivals after <PERSON> took office in 2015, and now his decision to split <PERSON>’s kingdom is, according to some, an act of revenge against the emir, his rival <PERSON>'s pick.\nThis adverse situation has disturbed the unity among Kano Kingdom households who have gotten along for centuries.\nCounting from the unification in 927, the British Monarchy is about 1,092 years old. Kano Kingdom was founded in 999, 1,020 years old.\nWhile the Brits will do all to uphold the dignity of their royal heritage, Nigeria is dismantling its own heritage over petty politics. Thread.\n— <PERSON> (@AyoBankole) May 8, 2019\nOn May 10, the courts instructed <PERSON> to halt the appointment ceremony of the new kings, but he defied the court and executed the division anyway, claiming he was carrying out the orders of the state legislature .\nSeveral palace officials decried Governor <PERSON>’s actions, calling it a distortion of a working model for governance in Kano and northern Nigeria. <PERSON> said he did not obey the court order because it came after the appointment of the new emirs in each of the five distinct sub-kingdoms: Kano, Rano, Karaye, Gaya and Bichi.\nHowever, on May 15, the court ordered a return to the status quo pending the hearing of the suit against the appointment of the new emirs.\nMany Kano residents, depressed by the division, said Governor <PERSON> is playing politics in diminishing the famous Kano Kingdom.\nThe Emir of Kano on his throne, September 2016.", "1017" ], [ "Photo by <PERSON> via Wikimedia: CC BY-SA 4.0.\nPolitical rivalry\nCurrent Governor <PERSON> worked as deputy governor to <PERSON> twice between 2011 and 2015.\nWhen <PERSON> was about to leave office, he called on <PERSON> as his deputy to run in the 2015 election. But since <PERSON> took office, <PERSON> has accused him of not being loyal, although <PERSON> denies these charges.\nDuring Nigeria’s 2019 presidential election, <PERSON> strategized to prevent <PERSON> from taking on a second term, but <PERSON> prevailed.\n<PERSON> has expressed hostility toward <PERSON> for supporting <PERSON>’s favored candidate, <PERSON>, of the People’s Democratic Party, during the 2019 election.\nThe two rivals have challenged each other with political blackmail through their supporters. <PERSON> has revoked all <PERSON>’s projects that he started as governor.\n<PERSON>’s move to split the kingdom is revenge against <PERSON>’s partisanship and another way to show disdain for <PERSON>.\nHe says the five new territories would operate as Kano’s sub-domains within Kano State. Jurisdiction for these territories would fall under <PERSON> — instead of King <PERSON>.\nA history of kingmakers\nBefore 1903, kingmakers determined the pick of Kano kings through family lineage. But with Europe’s widening influence in West Africa, ruling governors were given the power to choose kings beginning in 1903. Even though a prevailing democratic governor oversees Kano’s Emirate Council, it usually complies with ancestral customs of the kingdom.", "1017" ], [ "President <PERSON>’s Controversial Pardon Has Not Put Poles in a Forgiving Mood · Global Voices\nPolish lawyer and politician <PERSON> assumed the office of President in August 2015. Photo by <PERSON>, September 12, 2013. CC 2.0.\nEarlier this month, just a day after the new Polish government was sworn in, President <PERSON> made the controversial decision to pardon <PERSON>, a member of <PERSON>'s former party, Law and Justice.\n<PERSON> was convicted of abusing his powers as head of Poland's Central Anticorruption Bureau, where he served until 2009, during which time the Law and Justice party controlled the Polish government. Before his pardon, <PERSON>'s sentence had not yet entered force, as he was awaiting an appeal trial.\nAlthough the conviction itself was seen as controversial and some considered it a political move made by the previous government (controlled by rivals in Civic Platform), many say <PERSON>'s decision to pardon <PERSON> is surprising and possibly inappropriate. Had <PERSON> lost his appeal, he would have been barred from holding public office ever again, and he may have been sent to prison for many years. <PERSON> currently serves as the head of special services in Poland's new government.\nPolish social media users soon voiced their opinions on Twitter. <PERSON> wrote:\nPrzypominam, że ułaskawienie potwierdza wyrok.", "1017" ], [ "Od dziś o zainteresowanym można pisać per “przestępca”\n— <PERSON> (@konradniklewicz) November 17, 2015\nI want to remind you all that the pardon confirms the ruling. From now on we can call the person in question “guilty”\n<PERSON> also commented on Twitter:\nPAD to chyba zrobił Kamińskiemu krzywdę, bo ułaskawienie nie jest uniewinnieniem. Nie wiąże się z zatarciem. Nie znam się ale to głupie\n— <PERSON> (@FilipLachert) November 17, 2015\nI think that PAD [President <PERSON>] did a disservice to <PERSON>, because the amnesty doesn't mean “not guilty.” It doesn't equal an erasure of conviction. I'm not an expert but I think it was stupid.\nAnother Twitter user, <PERSON>, compared pardons issued by Poland's current and past presidents. As depicted in the picture attached to the tweet, <PERSON>'s pardon was suspiciously just a single sentence long.\nTak na obrazkach wygląda ułaskawienie normalne i ułaskawienie nienormalne: pic.twitter.com/EGi7CXfGBF\n— <PERSON> (@aronsem) November 20, 2015\nOn the attached pictures it can be seen how a normal act of pardon looks like, and how a not normal one looks\n<PERSON> also wrote about the pardon:\nPo to głosowałam na PiS i prezydenta <PERSON> by w moim imieniu ZAWŁASZCZYLI wreszcie państwo , wyrywając je z rąk złodziei i zdrajców\n— <PERSON> (@ISzafranska) November 19, 2015\nThis is why I voted for PiS [Law and Justice] and the Presient <PERSON>, so that they could reclaim the nation and pull it out of the hands of thieves and traitors\nSeveral members of the public complained that <PERSON> has compromised the presidency's impartiality and duty to represent the interests of the nation by indulging in partisan politics. While it's not illegal for the president to pardon a former colleague, <PERSON>'s decision has invited criticisms that he's violated the spirit of his obligations as Poland's leader.\nAlready divided after the elections, Polish citizens continued to be disagree about <PERSON>'s actions.\nPopular blogger and Twitter user <PERSON> posted:\nCoś czuję, że jak będzie za duży jazgot wokół tego ułaskawienia to wkrótce wypłynie jakieś nieznane do tej pory ułaskawienie poprzednika.", "1017" ], [ "Tanzania’s President Fires 10,000 Civil Servants Over Forged Qualifications · Global Voices\nTanzania's President <PERSON> addressing a crowd during the 2017 May celebrations. Press photo from State House.\nOn the eve of May Day, a day where the world pauses to honour its workers, the government of Tanzania shamed thousands of civil servants in the country.\nOn April 28, President <PERSON> ordered the immediate firing of almost 10,000 civil servants after an investigation found that some government workers had been occupying their positions with forged qualifications.\n“They are thieves like any other thieves,” <PERSON> was quoted as saying. “They could be jailed for seven years as the law says.”\n#Today‘s editoon #TheCitizenToday pic.twitter.com/W3Jak3P1sg\n— The Citizen Tanzania (@TheCitizenTZ) 1 de mayo de 2017\nThis purge comes a year after the government found that it was losing billions of shillings annually to tens of thousands of “ghost workers.”\nThe report, which looked at verifying the authenticity of 450,000 government employees’ qualifications, found that district municipalities led in the number of civil servants with forged certificates at 8,716. They were followed by other government-run institutions like the Sokoine University of Agriculture which had 33 people with fake qualifications and the Tanzania Railway Cooperation with 24.\n‘Safi sana’ news\nIt didn't take long for the internet to share its two shillings on the news.\nSome people expressed some sympathy for the sacked civil servants, asking <PERSON> to give those with fake certificates strength.\n<PERSON> tu hayo majina yanayopita huko Whatsapp but hii ishu inaumiza sana kimaisha na kisaikolojia#Mungu awatie nguvu wenye#VyetiFeki\n— Dr <PERSON> (@emgeni) 29 de abril de 2017\nJust take note of the names circulating on WhatsApp but something like this is heart-breaking and can affect someone psychologically.", "424" ], [ "May God give strength to those with fake certificates.\nOthers were cracking jokes about the whole thing.\n<PERSON>, <PERSON>, <PERSON>, <PERSON>\n— Charles Mtekateka (@mtekatekajr) April 29, 2017\nStarting next Tuesday, if you see a public official not going to work, playing with the kids at home, don't ask too many questions!\nGenerally, the news received a lot of “poa sana” (very cool) “safi sana” (very nice) as people are pleased that some action is being taken over the issue. Even former President <PERSON> came out publicly supporting <PERSON>'s move, saying the decision was “overdue.”\n‘…they love to give jobs to their family members…’\nOf course, there were people who took the matter less lightly.\n<PERSON> went on Twitter arguing for an independent commission to adjudicate the matter.\nKuwepo na Tume Huru itakayopokea malalamiko ya wafanyakazi #vyetifeki . Serikali can not judge its own case. @MariaSTsehai @humanrightstz\n— <PERSON> (@hyphym) May 1, 2017\nThere should be an independent commission that will listen to the complaints of workers with fake certificates. The government cannot judge its own case.\nMeanwhile, one opposition party, Alliance for Change and Transparency (ACT), tweeted that although they supported the government's drive against fake certificates in the civil service, they questioned whether the exercise went far enough.\nJambo la Pili lisilokuwa sawa, madai ya Waziri @AngellahKairuki kuwa mchakato wa uhakiki wa vyeti haujawagusa wanasiasa na wateule wa Rais\n— <PERSON> ✋ (@ACTwazalendo) April 30, 2017\nThe second issue that's not right are the statements by Minister <PERSON> that the process of verifying certificates does not implicate politicians and government appointees.\nThe party went on to suggest that the decision amounted to the government protecting some of its appointees.\n<PERSON> wa kisiasa katika zoezi la uhakiki wa vyeti ni ushahi wazi jinsi serikali inavyohaha kuwalinda baadhi ya wateule wa Rais pic.twitter.", "424" ], [ "Afghan refugees might complicate Ugandan politics · Global Voices\n“Nyakabande Refugee Camp in Uganda” by gsz is licensed under CC BY-NC-ND 2.0\nUganda is often praised as a model of hospitability for refugees. The country is home to at least 1.5 million refugees and has a remarkable open border tradition that spans decades, despite dealing with high domestic poverty levels. But the news that Uganda might be a destination country for Afghan refugees following the US withdrawal from that country in August 2021 has raised alarms in Uganda. Some local human rights defenders are concerned that accepting Afghan refugees might excuse President <PERSON>'s continued authoritarian rule.\nIn Today's @DailyMonitor page 12.\nAbout Afghan refugees and Ugandans deployed in Afghanistan. pic.twitter.com/ay1uhULZaP\n— <PERSON> (@BwoweIvan) August 30, 2021\nShare your thoughts on Uganda's move to host 2,000 Afghan refugees. #NBSLiveAt9\nCourtesy Photo pic.twitter.com/Ox4JKT5673\n— NBS Television (@nbstv) August 17, 2021\n<PERSON>, the State Minister for International Cooperation, told the Daily Monitor, a Ugandan daily news outlet, about a request by the US government that Uganda hosts the Afghan evacuees until their relocation:\nThey are not refugees; the US asked us on whether we could take them in temporarily as they are vetted possibly for relocation.\nBut before we could agree we asked them for certain information; under what terms and conditions, who are they bringing in — are they former soldiers, prisoners, translators, and for how long are they staying here? Once we are sure of that then we can agree.\nThe US embassy in Kampala confirmed the deal to confirmed to the Daily Monitor:\nWe deeply appreciate Uganda’s generous offer of assistance to host Afghanistan evacuees on a temporary basis. We have not yet made a final determination of assistance requirements in Uganda and discussions with the government of Uganda concerning the situation in Afghanistan, are ongoing,” a US embassy official noted.\nDivided public opinion\nThe previous controversy around refugees in Uganda had been about the Uganda Government's lack of accountability in managing funds. Some government officials were suspended in 2018 after allegations of fraud and refugee number inflation.\nMakerere University historian <PERSON> expressed fears that hosting the Afghan evacuees might threaten Uganda's national security. He told Deutsche Welle that:\nAfghan refugees may turn the attention of international terrorist groups such as al-Qaeda, al-Shabab, and ISIS to Uganda and destabilize the country.\nIn July 2010, 74 people were killed and 85 injured in twin bomb attacks in Kampala orchestrated by the Somalia-based Al-Shabaab. The attack was considered retribution for Uganda's role in the African Union's peacekeeping force fighting the extremist group.\n<PERSON>, a human rights lawyer, counters <PERSON>'s fears. In an interview with Global Voices, he said:\nIt is good for countries including Uganda to welcome Afghan refugees fleeing uncertainty and extreme circumstances in their homeland.", "328" ], [ "Human dignity, human solidarity and sheer necessity should allow us open arms to refugees and hope for a change in circumstances in their countries that would enable them to return to their homeland as a life in exile is no piece of cake.\nDespite the praise Uganda has received for its open-door policy, donor funding does not match it. By June 2021, the Uganda Refugee Response Plan was only 22 percent funded, leaving a considerable deficit to cover the food, health care, and education for refugee communities.\nGlobal Voices spoke to <PERSON>, a humanitarian response worker in Kampala, via phone. He said,\nThe first thing is to open borders and ensure the safety of refugees. There may be funding constraints, but we cannot refuse to let them (refugees) in. The Afghans are here temporarily as arrangements are made to resettle them elsewhere. Resettlement is a complex process and can take months. It is also cheaper to keep the refugees in Uganda than in other countries.\nHaven with a disturbing human rights record\nIn January 2021, Ugandan saw one of the bloodiest elections in its history. The government shut down the internet during election week. In the weeks leading to the elections, journalists were assaulted by Ugandan security personnel, human rights NGOs had their bank accounts frozen. At least 19 were killed in response to opposition protests in Kampala, and scores of opposition supporters disappeared and still remain missing.\nThe US government imposed a raft of sanctions against Uganda officials, citing human rights violations and undermining democracy. The US government's inconsistent policies in Uganda, including imposing sanctions while propping up the Kampala regime and now placing Afghan refugees under the care of the 35-year-old Kampala regime, raises questions about its commitment to human rights.", "328" ], [ "Ethiopia Imposes Nationwide Internet Blackout · Global Voices\nAn October 2016 protest in London by Oromo people over killings and human rights abuses at the hands of the Ethiopia government. Photo by Flickr user <PERSON>. CC BY 2.0\nOn May 30 at 3pm local time, Ethiopians found themselves unable to access the Internet. The blackout appears to be country-wide.\nIt appears that Ethiopian authorities imposed the nationwide Internet blackout in order to prevent “leaking of exam questions on Facebook” ahead of secondary school exams set to be administered over the next two weeks.\n24 hours after the total Internet blackout, Ethiopia still refuses to say why it shut down. Via @AFP pic.twitter.com/ZzJcX6Vqe8\n— <PERSON> (@zelalemkibret) May 31, 2017\nTwenty-four hours after the blackout, Deputy Communication Minister of Ethiopia <PERSON> told AFP that mobile data also had been deactivated.\nFinally, the Ethiopian government announced that the internet blackout will continue until June 8, 2017, reasoned by fear of ‘exam leaking’.\n— <PERSON> (@zelalemkibret) June 1, 2017\nLast year, the government was forced to postpone the national university entrance exam after the initial session was marred by a leak spread on Facebook.", "960" ], [ "Activists in the diaspora leaked questions on Facebook ahead of the exam in early June in 2016 after the government refused to re-schedule the exam for students who missed an entire semester of classes due to protests.\nBut the current blackout is different from previous mobile Internet and social media shutdowns that have been imposed in an effort to prevent exam leaking. This blackout is broader in scope and scale, effectively eliminating Ethiopia from the map of the global Internet.\nThis is especially easy for the Ethiopian government to do, since all Internet and phone service in the country is provided through through a single government-owned Internet service provider, Ethio Telecom. The blackout thus leaves businesses, banks, Internet cafes in Addis Ababa and social media pages of government media cut off from the rest of the world, making it harder for them to do their day-to-day work.\n‘Cos of the blackout: Banks are out of service, Bulk SMS services are not available, GPS services are not accessible …\n— <PERSON> (@zelalemkibret) May 31, 2017\nThe gravity of this move begs the question: Are authorities really just trying to prevent students from cheating on exams, or is there more to it? Indeed, this is just one among various reasons that Ethiopian authorities have used to justify censorship and shutdowns in recent years.\nEthiopia has blocked the Internet on three occasions since huge anti-government protests exploded in November 2015. Mobile and landline phone networks are also crippled in much of the country’s two biggest regions, Oromia and Amhara, where anti-government protesters have become common over the last two years.\nWhen Ethiopian authorities declared a state of emergency in October 2016 they officially blocked access to Facebook, Twitter and popular messaging apps such as Viber and IMO. Since Internet speeds are already incredibly slow, data-heavy video platforms such as YouTube have been rendered inaccessible even though they are not officially blocked.\nJust two weeks ago, activists inside the country reported that they were finally able to access Facebook freely, after many months of using VPNs and other circumvention tools to login to the social network. But with the country now in total blackout, they are now even more isolated from the rest of the world, and even from each other, than before.", "960" ] ]

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[ [ "Extremely Wicked, Shockingly Evil and <PERSON>\n<PERSON> i really didn't enjoy this like first of all the pacing? horrible. and the camera work/editing? that scene where <PERSON> and <PERSON> were talking and it just kept doing like a shaky spin around them and then it randomly cut and did another shaky spin over and over and over again... i got a migraine. and <PERSON> performance really wasn't convincing at all like it genuinely felt like he was just playing <PERSON> and then when they played the actual <PERSON> clips at the end the difference was so apparent :( <PERSON> was great though and i guess this film kind of kept me invested throughout even though this was such a boring portrayal of such an interesting story like i just wasn't expecting it to basically be a courtroom drama", "698" ], [ "The Batman\nnow, now. wow! this one was a really solid film! i wasn't expecting to like it the way i did since i'm not really into the dc universe, i'm more of a marvel guy, but i actually enjoyed it very much! i'm not even really fond of marvel movies too, i don't really expect too much on superhero movies actually, but this one was something else. it had a lot of strengths, the score and the acting, for example. that score! insanely good. that acting! are y'all crazy? every single person ate! the pacing was pretty good too. it was gripping. i wanted to get into the batman universe more.", "583" ], [ "the portrayal of batman in this was really interesting and amazing. the movie was long but it didn't feel long. i really thought i would just thirst over zoë & robert but i was fully invested. this is how i like my superhero movies, i suppose. it can be the best one out there, even. not cheesy, not bait-y? it had this story to tell and it told that pretty well. its biggest and maybe the only flaw was that one “not all cops” kind of moment, gives you the ticklish feelings, but i guess we can interpret that in different ways. deserves a rewatch.", "583" ], [ "Murder Mystery\nyou know there's some movies where <PERSON> presence doesn't completely ruin the experience for me and this... well this was one of those movies but only because every other character was soooooo perfect like idk i can never ever laugh at anything <PERSON> says ever it's just not in my genetic makeup so like having every single one of his lines being a joke was like. not as funny as it should've been for me but this was still so much fun like i guess it was objectively not the greatest movie of all time but it was still a good time like it had it all and i would literally DIE for <PERSON> and grace.... this was by far the best movie in the MOTOECM (murder on the orient express cinematic universe)", "217" ], [ "<PERSON> & <PERSON>\ni think this like might be the best film of all time... like yes i'm a sucker for happy endings so i would have ~prefered~ if they ended up sipping margaritas in mexico HOWEVER, this was so good :( so i'll forgive the ending just this time :( love <PERSON> and <PERSON> with my whole heart they were both so.... perfect.", "1009" ], [ "there really needs to be more films like this tbh films with strong female characters and films about strong female friendships are like my absolute favourite and then combining them and adding adventure... without question the best ~genre~ of all time and if that isn’t considered a genre.... it should be.", "269" ], [ "<PERSON>\nLOVED THE SCOREEE!!!!!!!!!!!!! and <PERSON>. Im gonna be honest here i wasnt completely with this movie, my mind was on how <PERSON> is at beyonce's renaissance premiere, but i read the wikipedia and i actually got all of the plot which shocked me.", "577" ], [ "Maybe this movie is a grower but i kind of just didnt care what was happening, i thought i didnt understand it but i did. So either theres something deeper that i havent read about or this is just the movie. Its a good thriller and the twist is ok but overall forgettable.", "236" ], [ "Master\nThis was one of those movies that was supposed to come last year but got delayed like most other ones. It was weird not getting a movie starring <PERSON> in 2020 since here that's like not getting an MCU movie..oh wait. Anyway my expectations were moderate and I was pleasantly surprised.\nThis is probably <PERSON>'s best movie I've seen at least in terms of his performance, instead if his usual ultra cool guy persona he is way more vulnerable and empathetic than usual while still carrying his usual coolness which I really dug.", "217" ], [ "<PERSON> is really great as the villain and has such a calm yet scary presence. This movie is also like...surprisingly depressing? It becomes so dark at points which I did not expect but it was pretty cool I guess. The songs really slap as well though they released them before the movie came out and they played literally everywhere which was annoying as shit but they're still really good. It's not perfect obviously, it could have been shorter and it's kind of a mess, but I can easily look past those issues and just go along with this fun ride.", "965" ], [ "tick, tick...<PERSON>!\nfinally watched rent at least the film, for this one. of course tick, tick... BOOM! is on my watchlist but it was not at all what i expected. after hearing his songs and a perspective into his life through this film, <PERSON> seems like a lovely and creative soul, which the dreamers can easily sympathise with.", "657" ], [ "♡ going back to the film, this was so great and executed well and i wish i can say <PERSON> works do not reach me as well as they do but now evidently more, it does. anyways i could not wait to bring him up, oh my god... <PERSON>! what a man how is he so phenomenal and why have i not been following his career more? i did not even know he could sing, im soso impressed by his performance and he truly made this film. again what a man.", "410" ], [ "Black Mirror: USS Callister\ndear <PERSON>,\ni am writing an apology to you because, no matter how much your physique or age changes, no matter how nice you can act and how you are in real life, i will forever dislike you for the sole reason of <PERSON>. im sorry thats just how it is and it is not your fault.\nthe only black mirror yet where i want to actually share my thoughts but i dont like doing that so i’ll just say yeah so good it could’ve just been a feature length film.", "1009" ], [ "pairs so well with white christmas which i loved. but also how the hell did they get <PERSON> at the end as a toxic gamer without the inclusion of a ‘yeah bitch’. still a bomb ass cameo but cmon <PERSON> you cowards", "585" ] ]

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[ [ "Let's look at a few reasons robots might want to eat (or at least hunt) others:\nBeing a predator lets you stay active all day\nSure you could be a boring robot and harvest solar energy. But this is not a very high power density. A car takes about 1L of gasoline to run 12 km. To have enough energy for a measly 1km ride, a robot with ideally efficient solar panels of 1m2 in perfect weather conditions will need to charge for almost 3 hours. You're really spending most of your day napping, and you're not going places. Then there is the night problem. We're not very good at storing electric energy. So at night you're mostly sleeping, too.\nThe same problem is going to arise for pretty much all renewable sources: low energy density + not available on demand. That would result in huge (which in turns consumes more power) and not very active robots. If your planet ran out of fossil fuel, generating your own energy makes you... essentially an easy prey. Predatory behaviors then seem like an efficient strategy (although it's more likely that being parasitic will give you better results; steal some batteries but don't kill the giant autonomous power station)\nIf you do have fossil fuel/nuclear energy, it is a bit harder to justify unless those resources are scarce enough to explain hunting for gasoline. But being dependent on fossil resources would probably lead to sedentary behaviour (you stay near that yummy puddle of oil that you found). That could still leave room for predatory nomadic species of robots.\nit's not about nutrition, it's about population control\nA robot can only last that long. Electronic components will oxidize, mechanics parts will rust, break, etc...", "435" ], [ "So the god-engineer who designed robotic life programmed the robots to \"recycle\": every robot seeks to produce another robot of his own species every 5 years (you don't want to have robots only making one copy, because your population will go down every time a robot breaks before reproduction, leading to an unevitable statistical extinction).\nWith every robot potentially making several copies, you need to avoid overpopulation, so hunting robots are designed. They are hunting primarily the older robots close to failure. There you have your predatory chain of recylcing robots. The predators also reproduce. They are not hunted, but if they grow too numerous, they will start starving(they don't have any other mean of energy generation), thus a carefully planned equilibrium is reached (see prey-predator models)\nN.B: You could have other, more ideal systems to maintain a fixed population. For example, just have the other robots build a new friend every time they detect a robot death in the world. But that would require for all robots to be connected and cooperating as a society. You could find a few reasons why this is not the case\ngetting resources is not hard, but crafting is a highly specialized task\nOk, maybe you have abundent fuel, but you still need to refine it. You have enough copper, silicon, etc but turning it into a processor to change yours or reproduce is another story. Those manufacturing processes are pretty complex and robots as we design them are usually good at one thing, not 1000. Very dexterous robots are unlikely to have a factory built inside them. So they need help from other robots. Sure enough you could do that in a peaceful way and build an economy around it... but if the processor-generating robots reproduce fast enough and are not very mobile, it's definitely easier to rip them open and get the goods directly.\nSo it's not so much a herbivor/carnivor dichotomy, it's more like you have specialized manufacturing units, and jerks who just take what they produce when they need it. The frequency of hunting in those conditions would be signifcantly lower tho (you might not need to hunt for a new processor before 10 years. Might be more regular if we're considering fuel)", "1008" ], [ "The undead body is preserved by magic.\nAnd that's the key. Treat magic as an almost-infinite resource easy to obtain but hard to replenish. Is a common setup in magic universes that \"magic\" is a consequence of the existence of living beigns. In other words, just imagine that \"mana\" is available in the whole world, but is more common or concentrated around places where life is more common as well, forests, big cities, etc...\nOn the other hand, living corpses uses magic for living; it could be a delicate ballance between living beigns spreading magic as they live and undead beighs consuming magic as long as they're living.", "227" ], [ "Create too many undead bodies and they wil deplete the magic of the zone quickly, and after that they will die (again) like my cell phone when it run out of battery. Or create just the right amount of undead bodies and they will consume the ambient magic at the same pace as it is replenished.\nIf the ratio of magic creation vs magic consumption is 1:1 (one living being spreads enough magic to sustain one unliving being) you tie the amount of undead bodies to the amount of living bodies so, if in some point of time the undead outnumber the living ones, they wouldn't last for long.\nLife and death are tightly related. It's obvious that one cannot exist without the other.\nNature don't like undeads, but tolerate them.\nIt is not natural for a dead being to be alive, every cell in the body of the undead is craving for resting forever. Well, you can cheat nature using magic but, the longer you cheat mother nature, the more it costs.\nIf the magic cost per day follows the graphic below:\nFor each day of existence (x axis), the magic cost increases (y axis), so after 100 days of unliving, dayly cost is almost twice as the first day and 200 days after the cost is multiplied by 8.\nNo matter how powerful the Necromancer would be, there would be a moment where the magic costs exceeds Necromancers power and this body cannot be kept living anymore.\nMaybe you can use both ideas at the same time! :)", "227" ], [ "Disguised as (human-sized) nonhuman animals\nA human brain may be hard to beat energy-wise: <PERSON>'s principle limits the efficiency of computers. Biology doesn't have nanotech, it is nanotech. No technology can make atoms any smaller. Thus the human brain may be basically as small as it can be without sacrificing intelligence.\nSo lets live in the amazon as Jaguars. 50 years after we put human neurons in a mouse brain we can transplant a whole human brain in a Jaguar body (its a bit of a tight squeeze in that skull but much more realistic than insect-size).\nSmall-tech\nA large industrialized factory is so (early) 21st centaury. What does a society need?\n1. Food: Jaguars can do that at Jaguar-level intelligence. High-tech human-brained Jaguars will have no trouble staying fed. Wear hidden AI cameras and the Capybaras are toast.\n2. Safety: It's hard to say how much of the Amazon will remain and what poachers will do. Thankfully, poacher tech is designed to catch Jaguars, not cyborg-enhanced Jaguars with passive radar and other detection methods. Artificial pelts and lab-grown meat are much easier anyway.\n3.", "335" ], [ "Opportunity: 2070 will have such exquisite virtual worlds a society can live a life of computers and tech. For work as well as play: you can design everything virtually with 2050-level physics engines. There is \"no\" need to build massive infrastructure until all your \"take-over-the-world\" blueprints are ready.\nBut my computers? Thankfully, photolithography reached the \"well-funded garage\" level in 2020, so by 2070 a basic fab can be carried in a backpack. Feedstock materials and spare parts are a problem, but they can be (laboriously) prepared with furnaces and other low-tech methods. It's far less efficient but its enough to barely self-sustain a tech industry. Moores law died around 2025 so being \"two decades behind\" isn't much of a loss, even with the underclocking and material choice you need to keep the chips alive for ~20 years.\nDon't blow your disguise!\nHumans in 2070 are aware that mind-downloading to animals is possible but it is rarely done: it is easier to replace organs or even whole bodies. And most who do so aren't in a secret society, they are just weird people in our society being weird.\nAlthough humans are not eagle-eyed for animals with human brains, they will begin to get suspicious with enough odd behavior, more so those who know how animals are supposed to behave. Humanized Jaguars have a natural quadruped gait, but spacing out into a virtual world is not really a <PERSON> thing. Also your paws look strange. Most items are carried inside the mouth or swallowed to look innocent, with larger items assembled like a well-machined jigsaw puzzle at destination. Furnaces and other infrastructure is disguised as a disorganized rock pile (and placed at the base of cliffs where rocks fall into talus piles anyway), etc. However, a close inspection by a human would reveal what it is. So stay safe, stay hidden!", "337" ], [ "ROBOTS!\nWhy send a bunch of under-evolved meatbags to understand a machine, when you can send the most advanced machine available to understand its alien counterpart?\nIf not, then two distinct teams\n1. the one aboard the reconnaissance vessel (you get it for free, given that they find the artifacts)\n2. a team of nuclear physicists/engineers, which arrives on a specialized ship equipped with our computers and large-AIs\nA bit of reasoning below.\nTL;DR sending a lot of humans in space for the just-in-case is way more expensive than sending just-the-necessary-right humans with a good encyclopedia and a powerful computer (we're in the future afterall).\nLet's consider a real-life case first: the discovery and study of the Antikythera mechanism. When we look at page listing the team that analyzed and figured out the artifact and its inner workings, one thing becomes evident: the team changed/expanded over time as the understanding improved and goals evolved. These people were of course working from the comfort of planet Earth, and relied heavily on computers and other types of equipment. A lot of the experts were simply there to be asked questions, but did not necessarily need to do any \"field\" work. Without detracting from their expertise, we can presume that an encyclopedia from the future could have been almost as effective in providing a similar level of contribution.\nBack to the case described by the OP, following the OP's timeline, there seem to be increasing understanding of the alien tech and thus changing goals. There are going\n1. The first team is already aboard the ship, if the ship was sent to study the celestial body. This is exactly as the OP outlined it. In fact all that they need to do is to identify the rocky formation, measure the radiation and raise a flag for sending someone to continue the research. I imagine we are talking about a chemist (also acting as geologist) and the ship's chief engineer, who is trained in nuclear physics. A geologist is unlikely to be aboard provided that rocks strata are not going to change quickly, and there is no need to dig/build/do anything with them during a reconnaissance mission. This team gets as far as wearing a suit and going on site to record radiation from close to the pillars, perhaps even collecting a sample.\n2. Radiation occurs spontaneously, so there must be something unusual about this particular case. Perhaps the next goal may be to understand the source/pattern of the radiation. There goes the nuclear physicists/engineers team.", "199" ], [ "Nuclear physicists and engineers do have enough computer science and math training to discover, identify and study unusual patterns. I imagine that the large AI can be found by looking at some kind of patterns. This team travels on a spaceship of the future, which will be designed to perform detailed analysis. We can safely expect the ship to have the equivalent of future wikipedia stored in its mainframe, as well as future state-of-the-art AI technology to assist in the analyses. This team has all the required knowledge to figure out the presence of a wormhole, the existence of antimatter reactors and engineer a simple interface to interact with them. I am not claiming that they will understand the mechanism, or that they will be able to reverse-engineer them, but that did not seem to be the question in the first instance.\nNotes: The following experts have been left on Earth:\n* Linguists. If current AI can translate between human languages today, future AI can probably identify some elements of communication between us and aliens.\n* Miners. Unless the goal is to extract the pillars, in the OP question there is no need to dig big holes.\n* Military, security details. Maybe they come for free as pilots aboard the ship. But considering that the planet/moon is inhabited, as reported by the reconnaissance mission, these people would just be useless cargo load.\n* Doctors, biologists. Beyond what's typically aboard future space vessels, there is no need to add any. All research can be done from the safety of spacesuits, or even within the walls of the spaceship, provided drones to go out an explore.\n* Mechanical engineers, architects. There was nothing mechanical in the structures identified in the reconnaissance mission. Also, the OP did not specify whether there was the need to build anything, in which case I'd rather send builders. Hence, beyond the chief engineer to look after the engine, there is no need for these expertise.\n* Radio/communications experts. to evaluate the signals and attempt contact with the AI.\n* Mathematicians, computer experts, theoretical physicists. Theoretical people are not exactly what is needed in the first step of looking at an artifact and figuring out how to interact with it. These are instead the people that may be employed later in reverse-engineering the apparatus.\n* AI psychologists, astronomers, archeologists, alienologists and historians.", "199" ], [ "People devise fortresses because in the past, the cost of defense is cheaper than the cost of attack. The defender builds a very high and thick stone/brick wall (certainly not cheap, but the cost is spread out throughout time)and station X amount of people on top of it, and the attacker will need at least 5 times the amount of people and equipment (immediate and present cost) to take it (just look at how many people is scurrying up the ladder, and how many is being killed on the ladder by arrow, hot water, burning log in the movies).\nIt is not until recently, when the advancement in long range artillery technology and modern mass-production industry that reversed the situation. Even the toughest wall can't hold against the repeat bombardment of cheaper, and more powerful artillery rounds that can be sent off the factory floor around the clock.\nAlso, smart generals from all era and places in history always try to dismantle a fortress without turning it into a slug match. <PERSON> has said that \"Attack a forturess head on is the worst strategy\", and <PERSON> (I forget whether it is him) has said something similar to \"If you barricade yourself in an impenentrable fortress, your enemy will seek other ways to get to you.\" A fortress must have self-sufficient food, water, medical, and basic manufacture ability to resist a seige. Special forces has been used to sneak into the fortification to destroy these vital facilities.", "121" ], [ "The larger the fortress, the more unfamiliar the inhabitants are to each other. This allows spys and sabotager to sneak in.\nTo make fortress prominent again, one of these factors must be eliminated. Perhaps this is after a nuclear war that decimated most of the factories around the world. The fortresses are the remaining factories, who needs to be defended with everything the defender has and who can pump out ammunition and other war machine as fast as possible while the attackers must use numerical advantage. Some new methods can be used to detect spys and sabotageurs, such as bio-integrated microchips or just a guard dog/bear/mechanical dragonfly.", "968" ], [ "Cyborgs vs Robots\nLet's imagine I have necessities to expand warfare into one of these two possible fields out of lack for different/previous options.\nBuild big war machines which are completely robotic, or breed kaiju-like big beasts using CRISPR (genetic editing) and then implement them through technology, turning them into cyborgs (even just to make them substain their own weight). An important note, such cyborgs would not be able to self reproduce (so they lack the fire&forget philosophy about bombing a planet with a couple of Xenomorphs Queen and let them overrun all other life forms).\nThey would be living beings with implemented muscles, skeletons, and weapons. On the other hand there are robots, fully machine. Same weapons, but no internal organs, biologic muscles nor veins.\nI would like to know which would be the better option.\nAt first I supposed it would be the cyborgs because they can self-feed through preys (enemies) but I quickly realize that robots could be structured so to ingest&melt fallen enemies in order to harvest calories and minerals/metals.\nSo I switched to robots.", "64" ], [ "Subsequently, I realized that robots can be hacked and you do not want for your billions-costed walking nuke to fall in the hands of the enemies. Plus I suppose robots would anyway need more energy than cyborgs in order to work.\nSo my curiosity switched back to cyborgs. I also realized that only an extremely advanced AI can work as efficiently as the instinct from a predator DNA would.\nAnd yet I reflected about the fact that cyborgs are easier to hurt I suppose (but a good armour would maybe do the work) and being living creature they would feel fear (pain can be shut down through meds).\nI would really love to hear from you, ranging from short&clever reflections to long mathematical computations about energy spent for the robots and/or economical costs (in this case feel free to include detailed maths about them for I have a bit of a background in those subjects).\nAn additional question is about how much of a cyborg would it be fitting to be cybernetic (weapons excluded). Bones must surely be implemented with metallic nanoparticles and an external armour is mandatory, but would it be better when it comes to cost/expense ratio of both economical resources and energy, to replace all organs with machines, or even create a robot and then just put a living brain in it so to avoid hacking? Or on the contrary, a fully living being with just a metallic skeleton/skin/fangs/teeth (and missile-launchers on its back but here we are speaking of a different matter)?", "64" ], [ "Note : this answer assumes the classic \"alpha/beta males\" behavior of wolves. After a bit of researsh (thanks <PERSON> in another answer's comment section), it turns out that this is not how wolves behave in the wild. Assuming that the seed of this behavior is probably somewhere in the wolf/dog DNA and that the question aims for a story, using this trope as basis appears safe enough to me.\nLike other answers already mentionned, the instinct is kind of already there. Let's see how it can be modeled to act like you want it to.\nWhat makes a dog loyal? It has a strong pack instinct.\nWhat makes a dog loyal to YOU? Because it sees you as the pack leader and it can't think of a reason of a way to overthrow you. It's fine as it is. Which I assume (not being a dog history expert), stems from the fact humans selected the most submissive kind of dog to when they started breeding them. This last part is based on my own personal (and limited) understanding of dog psychology. If this doesn't make sense, I'm afraid my answer just won't make sense.\nSo what about your dogs?\nPicture a dog engineered so that at some point in it's lifespan, it wants to be the leader, and it will. With just a few other changes in the dog's psyche, it essentially becomes a wolf that really wants to be the alpha male. And you are in its path. This gives us an easy explanation for why the beast wants to betray you.\nHere's the first effect of the genetic modification : at some point in it's lifespan, the beasts gets incredibly dominant until it's instinct dictates that it must be the alpha.\nAbout betrayal : how can the dog do more than just beat you up and run away\nOur hypothetical dog wants to kill you (or at least that you submit to it), but it will probably just wait for an opening, beat you up real good and take the lead.", "376" ], [ "At this point, we basically have an uncontrollable animal. This is probably not quite what you have in mind when you say betrayal, which is why we'll use the genetic engineering to change this.\nSo let's make the dog more subtle, it wants to stay close to you and cause trouble until something else kills you. This dog is patient and more methodical than your typical beast. The modifications that caused the surge in dominance also causes it to avoid confrontation with it's alpha until it's too late. This dog can actually understand playing a role and social manipulation.\nHere's the second effect of the genetic modification : the beast gets unnatural intelligence (for a dog). It instinctively learned in it's submissive phase to play sneaky with it's peers. So much that to an extend it can even get close to understanding how humans thinks and work in society. This also causes it to avoid confronting the pack's alpha directly. It will play the part until you need his help and take the mantle of alpha. After all, why would it take a fair fight if it knows how to avoid it?\nThis behavior would probably not be good in the wild if it was widespread. But if we accept that genetic engineering is in there, it doesn't need to make sense from an evolutionary perspective.", "376" ], [ "Put human bodies into suspended animation caskets (SACs)\nThis will be the most sustainable option because you do not need a lot of materials to run actual space. Living spaces must at all times be:\n* sanitized\n* monitored\n* air-conditioned\n* pressurized\n* lighted\n* gravitated\nThese requirements are just for designing a general livable space. Specialized living spaces like bathrooms, bunkbeds, kitchens, living rooms, cockpits, laboratories, viewing windows, etc., require a lot more conditions, meaning a lot more resources.\nBUT if you just put everyone to sleep, then you just need highly sophisticated bunk beds that also function as dining rooms, comfort rooms, and all sorts of utility rooms. Your only problem will then be all about running a place where interaction is necessary and/or encouraged, i.e. cockpits, laboratories, and living rooms.", "548" ], [ "My solution is just to\nPut human minds in full-immersion virtual realities (FIVRs)\nEverything in an FIVR is limited only by what computational power your ship can allot for such simulations. The only thing you need to ensure is the hierarchy of command within the ship, the accuracy of your simulation compared to real-world physics, and the correlation of the simulation with the control processes of the ship.\nBasically, you need to provide an interface for the simulation and the real world such that if the captain in the simulation decides to crank a simulated lever to steer the ship leftward, the ship will steer leftward based on the value of the cranked lever.\nIt would be like controlling the ship itself from within the simulation.\nThis simulation-reality correlation can be extended to all the other functions of the ship like\n* running the simulation\n* regenerating food sources\n* administering intravenous nutrition\n* navigating through space\nSummarizing: The freedom and safety you desire can be efficiently provided by virtual spaces. You can place a sophisticated, self-sustained, single-size bed anywhere on your ship. You only need that bed to be able to read and carry out the thoughts of the person on it. Maybe just add propulsion and the bed itself can become the ship, or link several of these beds together and equip them job-specific extra utility functions.\nTL;DR: By making the ship, the humans, and the interfaces between the two to be as integrated as possible, you do not need to know specifically where inside the ship should you put your humans.", "500" ] ]

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[ [ "Image Courtesy of <PERSON>\nThis review continues my series of detailed reviews that attempt to be part review, part resource for anyone not totally familiar with the game. For this reason I expect readers to skip to the sections that are of most interest.\nIf you liked the review please thumb the top of the article so others have a better chance of seeing it and I know you stopped by. Thanks for reading.\nSummary\nGame Type - Board Game (Tile)\nPlay Time: 50-70 minutes\nNumber of Players: 2-6\nMechanics – Set Collection, Tile Laying, Resource Management\nDifficulty – Pick-up & Play (Can be learnt in under 15 minutes)\nComponents - Excellent\nRelease - 2003\nDesigner -Dirk Henn -(All things Alhambra, Atlantic Star, Colonia, Eketorp, Granada, Metro, Rosenkonig, Shogun/Wallenstein, Show Manager, Speculation, Timbuktu)\nHaving reviewed each of the expansions to this great game, I figured it was time I returned to the game that started it all and give it the detailed review treatment. You can find links to each of the expansions at the bottom of this review.\nThe Theme\nIn Alhambra each player is seeking to build the greatest Alhambra of all time. To do so they need to use the skills of various craftsman from Europe and Asia to build the various areas that make an Alhambra. Each Alhambra will feature Pavilions, Manors, Mezzanines, Royal Chambers, Gardens and Towers.\nIn truth the craftsman themselves are not present but their various nationalities are represented through the inclusion of 4 different currencies, which are supposedly required to pay for their services. These currencies include Florins, Dirhams, Denars and Dukats. Well that’s my interpretation anyway.\nThe end result is a thin but interesting theme and one that encompasses a somewhat worldly feel.\nThe Components\nAlhambra represents ‘componenty’ goodness and with the help of an excellent tray insert, it all fits into a moderate sized box.\nThere is a flip-fold board which serves as the score track. It goes up to 120, which is a rather odd number. This score is likely to be achieved and surpassed by a player that has a good game. The score board is nicely illustrated featuring all of the building types featured in the game and each player’s fountain. It is slightly wider and longer than the scoreboard used in Carcassonne.\nImage Courtesy of Gelatinous Goo\nA 2nd board is provided and serves as the Marketplace.", "470" ], [ "It is dominated by 4 squares with a different currency type attached to each of the squares. Each square is also numbered, the reason for which I will explain later. This board is exactly half the size of the score board.\nImage Courtesy of <PERSON>\nSix smaller boards are provided for each of the 6 potential players. These are the Reserve Boards and as well as allowing a player to store tiles during the game, they also provide information regarding the Scoring Rounds and the number of Building Tiles that are available to be purchased. These boards are half the size of the Marketplace Board.\nImage Courtesy of Lurch104\nCloth Bag – A nice black cloth bag is also provided. This is used to hold the building tiles, which are drawn from the bag throughout the game.\nImage Courtesy of EndersGame\nThere is a total of 54 Building Tiles. There are 6 different types and each type comes in a different colour. They include – Pavilions (Blue), Manors (Red), Mezzanines (Brown), Chambers (White), Gardens (Green) and Towers (Purple). Each tile may have a number of walls around the edges and each tile also contains a numerical value from 2 to 13, which denotes their cost to purchase.\nIt's also interesting to note that some editions of the game use different names for some of the tiles.\nImage Courtesy of garion\nIn all there are 108 Money Cards. Money comes in 4 colours to denote the various currencies used in the game. They include - Florins (Yellow), Dirhams (Green), Denars (Blue) and Dukats (Orange).\nEach Money Card has a value ranging from 1 to 9. It is important to note that there is no correlation between the colour of the Money Cards and the colour of the Building Tiles.\nImage Courtesy of garion\nThere are also 2 Score Cards, which are used to engage the 1st two Scoring Rounds. They feature the points on offer for particular Scoring Rounds.\nImage Courtesy of EndersGame\nA set of 6 wooden player markers are also provided and come in vibrant colours.\nImage Courtesy of EndersGame\nThe rulebook is well presented, includes excellent examples and diagrams to explain rules and also includes sidebars and sections that stand out.", "84" ], [ "Image Courtesy of SuryaThis review continues my series of detailed reviews. I have tried to cover every aspect of the game and as such you may prefer to skip to the sections of most interest.\nSummary\nGame Type – Euro Game\nPlay Time: 30-50 min\nNumber of Players: 2-6\nMechanics – Tile Placement, Area Control & Influence\nDifficulty – Pick-up & Play (Can be learned in under 20 minutes and takes only 1-2 plays to fully grasp)\nComponents – Excellent\nRelease - 2002\nDesigner - <PERSON> - (Bali, All things Carcassonne, The Downfall of Pompeii, Mesopotamia)\nOverview\nThis review continues my detailed analysis of the Carcassonne series of titles and is the first of the expansions that I have looked at.\nI have no plans to cover the basic play and strategy of the base game here. If you would like to know more about Carcassonne, I suggest a quick read of this review –\nCarcassonne - A Detailed Review\nInns Cathedrals was released 2 years after the original game. It comes in a nice smaller box format and it is regarded as one of the ‘better’ expansions for the franchise.\nThis expansion review will outline what new elements and strategy are generated when using Inns Cathedrals and how that changes the feel of the play.\nComponents\nTiles – Inns Cathedrals offers up an additional 18 tiles to add to the Carcassonne mix. Tile distribution images like the one below are really handy if you mix a series of expansions together and want to separate them out again.\nImage Courtesy of Aldaron\nMore Meeple – Inns Cathedrals allows a 6th player to join the fun. They have to settle for grey Meeple though. Why so sad?\nImage Courtesy of mpot\nScoring Aide – A set of 50/100 scoring tiles help player's to keep track of their score should they 'clock' the score track.\nImage Courtesy of bluef0x\nLarge Followers – A key component to Inns Cathedrals are the new Large Followers that effectively give each player an 8th Meeple for placement on tiles.\nImage Courtesy of Ironmaus\nRules – The rules are printed on a small double-sided sheet, which means you will be able to absorb the new additions and get into playing within 15-20 minutes.\nImage Courtesy of EndersGame\nAll in all the components are up to the usual high standard of any Carcassonne title.\nNew Elements\nInns Cathedrals offers 3 new additions to change the play of the basic game.", "581" ], [ "It also offered a couple of little extras.\nNew Tiles –\nImage Courtesy of fivecatsInns Cathedrals adds 18 new tiles to the Carcassonne mix to make for a total of 90 tiles in play per game.\nThe Inns – Six of the 18 new tiles feature an inn nestled on a lake. All of these features are located next to a road segment, but some of them have a piece of city as well.\nIf a road contains one or more Inns, it will increase the value of each tile in the road network from 1 point to 2 points, provided it is completed. If the road is not completed by the endgame, then the road is worthless and will not score.\nThe Cathedrals – A total of 2 Cathedrals are featured in the game and they are surrounded by city on all sides (so they can only connect to city).\nIf a City has one or more Cathedrals present, each tile will increase in value from 2 points to 3 points (as well as any Pennants) provided that the City is completed. If a City containing a Cathedral is not completed by the endgame, then the City is not scored at all.\nLarge Meeple – Each player is also given a Large Meeple, which brings their ‘in-game’ total to 8 Meeple. This guy is placed in the usual way as standard Meeple but he is worth 2 standard Meeple when calculating who controls a feature.\nUnusual Tiles – Included in the tile mix are a series of unusual tiles (see Component Image above) such as one tile that features 4 ‘City Ends’ with a field in the middle. Another includes a Cloister with road at either side and a pointy piece of City that runs diagonally across the tile. I’ll outline the purpose of these later.\nAdditional Meeple – Inns and Cathedrals also offers a 6th set of grey Meeple to allow a 6th player to join the fun. These of course can be used with the base game without adding anything else from this expansion.", "84" ], [ "Image Courtesy of VerkistoThis review continues my series of detailed reviews. I have tried to cover every aspect of the game and as such you may prefer to skip to the sections of most interest.\nSummary\nGame Type – Euro Game\nPlay Time: 30-50 min\nNumber of Players: 2-5(6)\nMechanics – Tile Placement, Area Control & Influence\nDifficulty – Pick-up & Play (Can be learned in under 20 minutes and takes only 1-2 plays to fully grasp)\nComponents – Excellent\nRelease - 2003\nDesigner - <PERSON> - (Bali, All things Carcassonne, The Downfall of Pompeii, Mesopotamia)\nOverview\nThis review continues my detailed analysis of the Carcassonne series of titles and is the second of the expansions that I have looked at.\nI have no plans to cover the basic play and strategy of the base game here. If you would like to know more about Carcassonne, I suggest a quick read of this review –\nCarcassonne - A Detailed Review\nTraders Builders was released 3 years after the original game and a year after the highly successful Inns Cathedrals. It comes in a nice smaller box format and it is regarded as one of the ‘better’ expansions for the franchise.\nThis expansion review will outline what new elements and strategy are generated when using Traders Builders and how that changes the feel of the play. It will also look at any interesting interplay that may arise if used in conjunction with Inns Cathedrals.\nComponents\nTiles – Traders Builders offers up an additional 24 tiles to add to the Carcassonne mix and many of these tiles feature icons that represent Trade Goods (more on those later). Tile distribution images like the one below are really handy if you mix a series of expansions together and want to separate them out again.\nImage Courtesy of <PERSON>\nTrade Goods - A series of tokens are provided that feature the icons of the Trade Goods located on many of the new tiles. The number of Goods is not exactly the same for each type.\nImage Courtesy of <PERSON>\nMeeple – In this expansion we also get some specialised Meeple in the form of the Builder and the Pig. All colours are represented including the grey 6th player that was made possible by Inns Cathedrals.\nImage Courtesy of mpot\nCloth Bag – By now the designer and publisher probably realised that fans of the series would likely play with the base game and both the small box expansions, which meant a lot of tiles to mix and stack in piles.", "581" ], [ "So they included a really nice cloth bag, which allows all the tiles to be thrown in there and mixed up in a matter of seconds. It comes in Royal Blue (which matches the colour of the Carcassonne box, although some images on the Geek suggest other colours have been used) and it also features a nice Carcassonne transfer.\nIt is little touches like this that game fans appreciate. It also meant that each expansion to date had included a component that didn't affect the game play but did make the playing experience easier to manage.\nImage Courtesy of <PERSON>\nRules – Like Inns Cathedrals, the rules are printed on a small double-sided sheet, which means you will be able to absorb the new additions and get into playing within 15-20 minutes.\nAll in all the components are up to the usual high standard of any Carcassonne title.\nImage Courtesy of <PERSON>\nNew Elements\nTraders Builders offers 3 new additions to change the play of the basic game. It also offered a couple of little extras.\nNew Tiles – Traders Builders adds 24 new tiles to the Carcassonne mix to make for a total of 96 tiles (using base game) or 114 tiles in play (if also using Inns Cathedrals) per game.\nThe Trade Goods – Justifying the ‘Traders’ part of the title, 20 of the new tiles feature a particular goods symbol. The goods include Wine (9), Grain (6) and Cloth (5). These goods are always located within a piece of City.\nWhen a player places a tile that completes a City, they are allowed to take 1 matching Goods Token for each icon located in the City. This collection is done regardless of who owns the Meeple in the City and they are awarded even if the City contained no Meeple.\nAt the end of the game, 10 points are awarded to any player holding a majority of tokens in any one Trade Good. Thus a total of 30 points can be earned in this way at games end. In the event of a tie all players are entitled to the 10 points.", "84" ], [ "This review continues my series of detailed reviews that attempt to be part review, part resource for anyone not totally familiar with the game. For this reason I expect readers to skip to the sections that are of most interest.\nImage Courtesy of <PERSON>\nSummary\nGame Type - Euro Game\nPlay Time: 90-120 Minutes\nNumber of Players: 3-5\nMechanics - Auctions/Bidding, Set Collection, Trading/Negotiation, Dice Rolling\nDifficulty - Moderate (Can be learned in about an hour, takes a game or two to get a handle on how to do well)\nComponents - Excellent +++\nRelease - 2007\nDesigner(s) - <PERSON> (6 nimmt!, Auf Achse, El Grande, Expedition, Goldland, Gulo Gulo, Hacienda,Heimlich & Co., Java, Maharaja: The Game of Palace Building in India, Mexica, The Palaces of Cararra, The Princes of Florence, That's Life!, Tikal, Torres and many, many more)\nand <PERSON>\nOverview\nForget the grand stadiums of the modern era and travel back to one of the greatest engineering feats of the ancient world...the Colosseum! As an Impresario you are charged with putting on the greatest spectacles the Emperor has ever seen as a celebration is held for 99 days to commemorate the opening of your very own stage...the Colosseum!!!\nThis ... is ...SPARTA!!... err Rome.\nIn Colosseum each player is looking to stage the grandest spectacles ever seen...featuring; gladiators, lions, chariot races, galleys to sail on a flooded arena, musicians and narrators. Your aim is to draw the largest crowds and to hopefully have the honour of being graced by the presence of dignitaries such as Senators, Consuls and perhaps even the Emperor himself.\nThis is your life's work and you are hoping to earn the title of Grand Impresario.\nWelcome to Colosseum!\nPlease join tour group 3 as I take you around this grand structure and show you what it has to offer...\nThe Components\nThe spectacles of the colosseum were many and varied and Days of Wonder (DoW) certainly match it with a ton of bits for this game. There is a lot to get through so let's get stuck in.\nBoard – Ironically the board, whilst important, is not as impressive as some of the other components as it features rather neutral tones to allow other components to stand out once placed on the board. It is still nice to look at though.\nRather than depict the Colosseum, the board illustrates the city of Rome with its many buildings, port and river. But this is actually rather unimportant and instead the eye is drawn to the 4 key features that are of importance.\nCentrally there is the Market area, where there are 5 groups of 3 boxes.", "470" ], [ "This is where the Asset Tokens are placed to be auctioned off during the game.\nAround this in a rectangle formation is the track upon which the dignitaries are placed and can move as the game unfolds. This track also allows space for each player's Arena.\nAround the outside of the board is the score track and there is also a Turn Order Track located inside the path of the dignitaries.\nImage Courtesy of <PERSON>\nDignitaries - In all there are 6 wonderfully lavish pieces that represent the Emperor, two Senators and three Consuls. These appear to be made out of wood but they have some ceramic embellishments that make them look neat and provide them with a nice heft that sits lovely in the hand. The quality is not only fabulous but it also serves to highlight their importance in the game itself.\nImage Courtesy of Toynan\nAsset Tokens - In all there are 12 different asset tokens that can easily be made out by their image. Each asset is easily identifiable thanks to a unique background colour and they have that thickness that makes them feel like a quality component.\nThe Asset Tokens feature either a green or a yellow back. It is the green-backed tokens that are largely used in the set-up with the yellow-backed tokens starting the game in the drawstring cloth bag.\nImage Courtesy of <PERSON>\nStar Performer Awards – There are 7 Star Performer Tiles that match 7 of the Asset Tokens and this connection is reinforced by using the same background colour. A nice large +4 reinforces their benefit and these are highly sought after as the game unfolds.\nImage Courtesy of <PERSON>\nEvent Programs - A key feature of the game are the Event Programs that the players are trying to produce. These are horizontal templates that get longer as they get more elaborate.", "84" ], [ "Image Courtesy of Debate\nThis review continues my series of detailed reviews that attempt to be part review, part resource for anyone not totally familiar with the game. For this reason I expect readers to skip to the sections that are of most interest.\nIn addition this is the 3rd in a series of reviews that will focus on the Kosmos series of 2-Player games. A full list of titles I plan to review or have reviewed from the series can be found at the bottom of this review (Pick & Pack was also included but is not a Kosmos game).\nSummary\nGame Type - Card Game\nPlay Time: 20-40 minutes\nNumber of Players: 2\nMechanics - Racing, Hand Management\nDifficulty - Moderate (Can be learnt in 30 minutes & a play or 2)\nComponents - Excellent\nRelease - 2002\nDesigner - <PERSON>( Aton, Cape Horn, No Thanks!)\nOverview\nIn Odin's Ravens, each player assumes the identity of one of <PERSON>'s ravens; Hugin or Munin. Every morning <PERSON> sends these two ravens out to watch over his lands and it is at these times that the two ravens would race one another. So effectively each player is racing one another with the winner presumably earning bragging rights and <PERSON>'s affections...maybe? (I'm just making stuff up now).\nUnlike many of the games in the Kosmos Series, the game play actually lends itself to the theme as each player must speed their raven across the landscape cards as quickly as possible. The game takes several races to determine the winner and the key mechanic of managing your cards (in hand and once played) are key.\nThe Components\nOnce again the components are very good in Odin's Ravens but they are perhaps not quite as eye catching as other games in the series due to the lack of a board or real character based artwork.\nRaven Tokens - Each player is represented by a functional, but nice, wooden token in the shape of a raven. One raven is coloured grey and the other brown.\nImage Courtesy of Debate\n<PERSON> - A small, raised wooden disc featuring a thunderbolt symbol of one side is called the Odin's Marker. Its purpose will be outlined in the Game Play section below.\nCards (General) - The game comes with a total of 106 cards. Kosmos seem to like producing cards of unusual dimensions for their games and if nothing else the decision certainly does help their games stand out in one's memory.\nAll cards used in the game feature the same dimensions, which are 8cms longer than a standard playing card (but shorter than those used in Lost Cities) and they are about 2/3rds the width of a standard playing card. This all means that the cards are narrow and longish, but they are still easy to hold.\nFlight Cards - Each player uses their own deck of 33 cards, although both decks are identical in their make-up.", "299" ], [ "Flight Cards account for 25 cards in each deck and each card depicts a single terrain type such as; a river, river, forest, canyon, hills, and snow covered mountains.\nThese cards feature the terrain artwork centered on the card and smaller icons of the same image are located at the top and bottom of the card. This is a design feature to ensure that a card type can still be identified when the cards are fanned during play.\nImage Courtesy of Honey\nOdin Cards - The remaining 8 cards in each player's deck are Odin Cards, which feature a picture of <PERSON> holding a stone tablet that contains text. Each tablet displays the two options that are possible by playing the card (more on that later). There are a total of 4 different <PERSON> cards of which there are 2 of each.\nImage Courtesy of Terraliptar\nThe rear of the cards used in the player decks depict a birds eye view of <PERSON>'s lands, featuring each of the terrain's used in the game. A raven flies through the sky as if surveying all that is below.\nThe card backs are differentiated by being either grey or brown, which matches the colour of the player raven tokens. All neat artistic design decisions.\nImage Courtesy of petersjs\nLandscape Cards - Then there are the 40 Landscape Cards, which are used during the game to create the Flight Path that both birds must negotiate. Rather efficiently each card features 2 different landscapes which are drawn in a mirror image fashion. This allows a single Landscape Card to represent a new section of the Flight Path for both players. A crisp dividing line separates the mirror images and clearly identifies that each landscape is independent of the other.\nSome land cards feature 2 different terrain types, whilst others feature the same landscape for both players. Not surprisingly the images used for each land type are identical to those used for the Flight Cards in the player decks. By now some of the mechanics are becoming clear.", "937" ], [ "This review continues my series of detailed reviews that attempt to be part review, part resource for anyone not totally familiar with the game. For this reason I expect readers to skip to the sections that are of most interest.\nImage Courtesy of <PERSON>\nSummary\nGame Type - Card Game (Expansion)\nPlay Time: 25-45 minutes\nNumber of Players: 2 – 8 (Best 3+)\nMechanics - Card Drafting, Set Collection, Variable Player Powers, Simultaneous Action Selection\nDifficulty - Pick-up & Play (Can be learned in 10 minutes and only takes 2-3 plays to get a handle on the thinking required)\nComponents - Very Good\nRelease - 2012\nDesigner - <PERSON>( Ghost Stories, Hanabi, Mystery Express, Takenoko)\nWhat’s the New Take with ‘Cities’?\nThematically, 'Cities' introduces those less tangible, less visible elements of a city from antiquity. They might be less savory on the surface but they are no less important to the workings of any city. Slave Markets, Gambling Dens, Black Markets and Hideouts are all to be found in 'Cities'.\nBut then there are those other elements too, those necessities that have a more subtle influence over how the cogs of power turn. These include organisations like Secret Societies and Spy Rings, whilst bureaucracy is represented with Embassies and Consulates.\n‘Cities’ also offers up 2 new City States in the form of Byzantium and Petra, both of which have new Wonders to construct.\nOf course to ensure that this new expansion fits the needs and basic play of the base game and the 'Leaders' expansion, it also provides a selection of new Guild Cards and Leaders, which make use of new abilities offered up by Cities.\nI will not be covering the basic play of 7 Wonders in this review. If you would like to know more about the base game I suggest that you check out my review here –\n7 Wonders - A Detailed Review\nA link to the first expansion can be found at the end of this review.\nThe Components\n'Cities' comes in the same style of box used for the 'Leaders' expansion. Being a cad game, the extra additions are largely cards but there are a few more new bits here than in the last expansion.\nCity Cards – In all there are 27 new 'Cities' cards that are distinctive due to their black background colour. The 27 cards are nicely divided into 9 new cards for each of the 3 Ages, and in terms of design, art quality and design features, everything is up to past standards so the cards fit seamlessly into what has come before. I have seen some complaints that the backs of these cards differ slightly from past 7 Wonders products but that is not the case with my copy.\nOf course new icons are present to help implement the new mechanics introduced with the expansion, but I'll cover those in a moment.\nImage Courtesy of a_traveler\nNew Guild Cards – In all 3 new Guild Cards are provided.", "299" ], [ "I will discuss each of these in turn later in the review.\nImage Courtesy of a_traveler\nNew Leader Cards –6 new Leaders are offered up by 'Cities'. Some feature new icons from this expansion, others tie in with powers first seen in 'Leaders' and then there is a scoring based Leader that completes the set of VP scoring cards seen before now.\nImage Courtesy of a_traveler\nByzantium and Petra City States – 'Cities' offers up not one but two new City States in the forms of Byzantium and Petra. Both are interesting inclusions with one offering big VPs and the other incorporating the new Diplomacy mechanic.\nWhat remains the same is the lovely artwork that depicts the scene in both City States.\nByzantium is the stand out as it features a gorgeous dusk skyline and the splendour of domed buildings. The city curves its way around the harbour and a real sense of scope is created. It's really a lovely vista.\nImages Courtesy of a_traveler\nDiplomacy Tokens – 3 Diplomacy Tokens are included, which are represented by large stand up tokens featuring a dove in flight. They need minimal construction - the insertion of 2 stands in the base. Think of the Stone Age 'go first' token and you pretty much have it.\nImage Courtesy of a_traveler\nDebt Tokens – A new form of token is also introduced in 'Cities' called the Debt Token. These come in -1 and -5 increments and they are square and rectangular in shape. They represent the potential for a City State to be bankrupted and those minus scores are obviously a hit to your end of game VPs. Nasty!", "872" ], [ "This review continues my series of detailed reviews that attempt to be part review, part resource for anyone not totally familiar with the game. For this reason I expect readers to skip to the sections that are of most interest.\nImage Courtesy of ArtEmiSa64\nSummary\nGame Type – Dice Euro Game\nPlay Time: 30-60 Minutes\nNumber of Players: 2-4\nMechanics – Dice Rolling, Area Control/Influence\nDifficulty – Moderate (Can be learned in about 30 minutes)\nComponents – Excellent\nRelease - 2006\nDesigner – <PERSON> - (Jaipur, Jamaica, Metropolys)\nOverview\nYspahan was one of the first Dice Euros to hit the market way back in 2006 and comes to us from a designer that has had more success in recent years with games such as Jaipur, Jamaica and Metropolys.\nYspahan takes us back to the year 1598 when Yspahan becomes the center of the Persian Empire. As merchants the players are hoping to make great riches in this boon time by getting their wares into the many shops of the Souk District, supplying the great Camel Caravans that venture out into the desert and by building new structures as a sign of their new found wealth.\nI should have given this game more love with a detailed review long before now being a fan of dice based Euros.\nThe question is, 'How does Yspahan stack up against the competition now?' given that the genre has exploded in recent years.\nThe Components\nYspahan is a Euro done pretty right in relation to components.\nMain Board – The main board of Yspahan depicts the city which consists of many shops. The city is further divided into four neighbourhoods, which are separated by a road upon which the Supervisor will travel during the game. Each neighbourhood features shops of various colours and a set of like coloured shops is referred to as a Souk. Each set of coloured Souks in a district is worth a certain amount of points and each neighbourhood is given a symbol to help identify it (sack, barrel, vase and chest).\nThe top left hand corner features a day and week track to help mark the passage of time as the game unfolds and a scoretrack surrounds the city.\nThe board is certainly colourful...some may even think it garish but it is functional and pleasant enough to look at.\nImage Courtesy of theo home\nTower Board – The second most important component is the Tower Board. This is placed alongside the main board and is used to allocate the dice that are rolled for each day of play.\nThe board consists of 6 rows, with the four neighbourhoods sitting in the middle, a coin row at the top and a camel row at the bottom. On the right hand side of each row are 3 symbols, which remind players of what they can do with the dice found there.\nImage Courtesy of toulouse\nCamel Caravan – Now we have the Camel Caravan Board which features a series of camels in three rows.", "581" ], [ "This board is used to allow players to send goods to the Camel Caravan in order to score points. The first camel in each row is fainter in shade to reflect that it is not used if only 3 people are playing.\nImage Courtesy of <PERSON>\nPlayer Boards – Each player must take a Player Board which shows a total of 6 buildings, their benefit at the top, their cost at the bottom and a VP tracker on the right hand side. These are a nice bit of design and the boards are suitably thick to stand up to many, many plays.\nImage Courtesy of <PERSON>\nCamels - Games are always more cool when they have Camel Meeple and <PERSON> delivers with some cool stylised wooden camels that make for some great images, which I've used throughout this review.\nOh yeah what was my girlfriend's comment upon her first play this week, \"Yay Camels...they're so cute!\"\nImage Courtesy of Legomancer\nSpecial Cards - Yspahan comes with a total of 18 Special Cards of which there are 9 types in all and 2 of each. These offer up many a special power to help out the players. The cards are of the small format featured in many games and suit their use here (not needing to be held in hand).\nImage Courtesy of dougadamsau\nBits and Pieces - The game then offers up a bunch of odds and sods. Each player takes a set of coloured cubes and these are used to represent their goods. Yellow discs are used to represent gold and a bunch of dice are provided that come in white and three in yellow. A black pawn is used to mark the start player and a white pawn acts as the Supervisor. Two white cubes are used to track the current day and week.\nThere is nothing magical here but it is all does the job.", "872" ], [ "Image Courtesy of ny2007\nThis review continues my series of detailed reviews that attempt to be part review, part resource for anyone not totally familiar with the game. For this reason I expect readers to skip to the sections that are of most interest.\nIf you liked the review please thumb the top of the article so others have a better chance of seeing it and I know you stopped by. Thanks for reading.\nSummary\nGame Type – Euro Game\nPlay Time: 40–60 minutes\nNumber of Players: 2–4\nMechanics v Action Points, Area Control/Influence, Pick-up & Deliver, Point to point movement, Set Collection\nDifficulty – Pick-up & Play (Can be learned in 20 minutes)\nComponents – Good\nRelease – 2004\nDesigner – <PERSON> – (Africana, Architekton, Aquaretto, Boss Kito, California, Call to Glory, China, Coloretto, Coney Island, Don, Draco & Co., Dschunke, Felinia, Fist of Dragonstones, Gold!, The Golden City, Han, Industria, Industry, London Markets, Magna Grecia, Mogul, Mondo, Paris Paris, Rat Hot, Sushi Express, Valdora, Web of Power, All things Zooloretto)\nOverview and Theme\nWelcome to Europe in the 14th century and more accurately the Hanseatic city-states that occupy the coastline of the Baltic Sea! It is a time of naval trade, a time when fortunes can be made by the savvy merchant and navigator. All you need is the wind at your back and an eye for the goods that are in demand. Set up your trade networks to take advantage of the supply and demands of the day and the world's power and prestige can be yours!\nHansa is one of those 'under the radar' games by <PERSON> many a new gamer to find the hobby would be quite unaware of. This was released back in the day when Uberplaywould release quite reasonably priced games and months later they would be bargain bin'd on Tanga (which was all the rage back then).\nGrab those trade papers there and help me get these goods on board...we are setting sail for a city a yonder!\nThe Components\nThe components to Hansa are fairly indicative of Euros in that 2004 time period. That is not to say that they are bad in any way, but by today's standards I could only call them functional.\nBoard – The board is a something of a mixture of minimalist meets downright ugly. The map itself is dominated by 9 key cities, the Baltic Sea and arrows that represent trade winds or movement patterns of the trading vessels.", "470" ], [ "The land is largely marked with trees to represent the forests of the age and smaller circles adorn the board to allow for the placement of Goods Tokens.\nThen there is the colour palette. Really this is something bordering on hideous. It's a mouldy green/yellow colour and it really does look like someone has gorged themselves on cheese whiz or something similar, chased that down with a slab of beer and then visited the little boy’s room to relieve themselves of the contents of their stomach.\nI'm not sure if this was meant to simulate an old map of the region or not, but the end result is anything but appealing.\nImage Courtesy of EndersGame\nMarket Booth Tokens – These are represented by the classic wooden discs that were so common in games from 1995 through to about 2007 ( from 2000 springs to mind pretty quickly). These tokens are used to represent the Market Booths that the players have established in the cities of the region.\nImage Courtesy of EndersGame\nMoney Tokens (Talers) – The money tokens or Talers are gold in colour and feature traders in a boat and some sort of commerce based motive in the background. They also have some form of Latin or Celtish-styled writing around the outer edge. This could all be based on some form of coin used in that period or be total creation, I am not sure.\nThese tokens are slightly smaller in diameter than the tokens used for the goods.\nImage Courtesy of EndersGame\nGoods Tokens – These are perhaps the most important component to the playing of the game itself. These tokens display both the type of good on offer (denoted by a coloured background of which there are 6 types) and the quantity - one to three barrels.\nThese are cardboard tokens and the thickness is pretty good. The rear side features the same image used on the board for the Warehouses and this allows these tokens to be placed face-down on the supply circles so the players do not know what is coming next.\nThey do the job well.\nImage Courtesy of <PERSON>\nMoneybag Tiles – This component is a large round cardboard token that represents the Talers that a player has in their possession.", "84" ] ]

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[ [ "Borneo Island: Uniting bloggers through Borneo Colours · Global Voices\nKellybays, Tuaran, Borneo. Photo by <PERSON>\nBorneo Colours is a website that links bloggers from Brunei, Sabah, Sarawak, Labuan (Malaysia) and Kalimantan (Indonesia) which are all located in the island of Borneo. It's a platform for the bloggers in this region to network and create greater understanding about their neighbours.\nTo date, Borneo Colours or BC has over 1,000 members with almost 200 registered bloggers and the number is said to increase daily. Speaking to the CEO and founder of the site, <PERSON> shared with this author the history of the website.\nThe idea came about during the early part of 2002. The aim was to facilitate and encourage Borneans to show goodwill to the world. Later, the founder realized the huge financial challenge in maintaining the project called “Borneo”. Eventually in 2007, BC was quietly launched but sadly the idea was momentarily put aside as the founder was offered to assist an international NGO in initiating a marine conservation project. It was in early 2009 that the founder decided to bring the idea back to life. Around July 2009, armed with fresh funding and support, Team BorneoColours.com began their work by promoting their ideas to the Borneo Island Community and tourism bodies in Sabah, Sarawak, Labuan, Brunei and Kalimantan. BC had its soft launching on 25th September 2009 but it was only last January when it became operational.\nPhoto by <PERSON>\nWhat are your aspirations for Borneo Colours?\nTo be the official new media and community portal endorsed and recognized by governments within Borneo island, but most importantly by the Bornean and international online community. Our goal is also to shape borneocolours.com as a mechanism for a transparent sustainable financing to raise funds for local charity organization, community development and environmental awareness activity on the island.\nWhat can one get from reading/being a member of Borneo Colours?\nContent is provided and shared primarily by registered members also known as bcbuddy.", "696" ], [ "The community shares content by promoting events, happenings, or showcasing their talent and interesting articles that would be of help to others. There is also the Borneo Business Directories and Bloggers Listing. One particular feature that Borneo Colours is proud of is the integration of our content and a social networking tool similar to Facebook.\nYou got a Blogging Competition going on at Borneo Colours? What do you aim to achieve from that competition?\nBorneo Bloggers Award 2010 was designed to give prominent and upcoming bloggers in Borneo island a network window to understand, accept and appreciate each other's differences but most of all to create a sense of Borneo without borders. We are also hopeful that this program will help Borneo bloggers to be much competitive and improve their content, style and creation of original content. At the end of the day, who else is better in promoting their tourism destination and attraction if not the bloggers themselves.\nAny future plans?\nBorneoColours.com will be organizing a dialogue called B2.0 as in Borneo2.0 “Borneo Bloggers + New Media Dialogue”, This dialogue is schedule to be held at 1Borneo, Kota Kinabalu, Sabah in mid-October 2010. B2.0 would bring together diverse blogging communities and creative local and international new media practitioners to provide rich opportunities for learning, networking and growth.\nMany bloggers from the island of Borneo are endorsing BC:\nA Woman Diary says ” It's practically everything you wana know about Borneo. Made by Borneo-an. I like”\n<PERSON>, a BC buddy has this to say in introducing Borneo Colours.\nAre you a BC Buddy? If not, why don't you guys check out BorneoColours. Its a site where you can get info surrounding Borneo designed with a social networking function, BC Buddy. BC Buddy is a place for online community to hang out like other social networking site.\nChoco8Vanilla says that\nBorneo Colours is a website designed to gather people to know more about borneo or to gather the people of borneo itself to know more about its beloved island and the latest news or just simply, be friends (Isn't it great? XD). The site is new. But everyday its more new people coming, don't you want to be part of this beautiful community? Its a bit… kinda same… or so alike… facebook or friendster or tagged (maybe?) Besides the website, I had one more thing (should I stated here WOW!", "696" ], [ "Brunei: Great Tasty Tour goes East Asia · Global Voices\nTwo Spanish Foodie Bloggers, <PERSON> and <PERSON>, are currently on a gastronomy tour in East Asia for some ten months. They left their jobs and much of their belongings behind due to their strong interest to learn more about Asia, its people, culture and history via food. They are currently in the Republic of Korea and intends to return to Spain in October 2010, where they hope to produce a series of videos about their adventure. Blogging in Spanish, The Great Tasty Tour documents their journey to the many countries in the region. What amazes me about the Spanish couple was their passion for food and getting to understand the local culture. I personally caught up with the couple during their Brunei leg of journey last December 2009. Read about them on Brunei Times but it was my affiliation with <PERSON>, who informed me on the Great Tasty Tour's intention to meet local foodie bloggers. Together with <PERSON>, we took them to various foodie joints in the capital, including the infamous Gadong Night Market.\nAnother local blogger, <PERSON> invited the two Spanish foodie bloggers to his restaurant and blogged about their visit.\nIt was a great opportunity to meet <PERSON> and <PERSON> blogger from Spain, who are currently travelling in East Asia, to document their gastronomy travels and spending their New Year with us recently. They both speak some English, so we are able to communicate with one another. They both spoke about Brunei and are happy to be here for a short stay and discovering many thing about our food. Here are some of the videos taken by them at the recent visit to our Brunei Restaurants with Great Tasty Tour.\nI asked <PERSON> and <PERSON> a couple of questions about the whole idea of the foodie trip.\n1. What is your background story for the Great Tasty Tour?\nWe have always had a dream, to know the East Asian cuisine. Firstly, because when we visited some countries in this part of Asia almost four years ago, we fell in love with its food and its people. We wanted to investigate what people in these countries eat, also where they eat and why. It was our great dream and is becoming a reality.\n2. What is the inspiration to tour Asia and try the food?\nOur inspiration came from the trip we did in 2007. We visited French Polynesia, New Zealand, Brunei, Indonesia, Singapore, Hong Kong, Australia, China and Japan.", "340" ], [ "The truth is that we fell in love with the flavors of Brunei, Padang food and Chinese. We had the need to further develop the theme and give it to meet the people.\n3. How has the trip changed you, especially your perceptions of Asian Food and people? Do you miss home?\nLife changes because we have had the opportunity to meet so many different cultures, we see all life more simple and the material thing loses value, feelings will be with us forever. We have discovered the true kindness in the people of many East Asian countries, especially in Indonesia, Brunei, Malaysia, Taiwan and China. Maybe is because in those countries, people love their food and love sharing it with us. Also in these countries, it has been easier to record our documentary because they understood our passion.\nWe do not miss our house because we are doing what we love, in fact we miss countries where we would have liked to spend more time eating and enjoying their meals and spend time watching quietly. (You know we would like spend more time in Malaysia, Brunei and Indonesia, they have been the big discovery for us.)\n<PERSON> and <PERSON> in Bruneian traditional costume. Photos reproduced with permission from Hyperclicks\n4. What have you learned in Brunei?\nIn 2007 we were in Brunei for five days. In 2010 we were in Brunei for 14 days, and we learned many things. A country that is different from the rest of the world and better. When we visited for the first time we feel very good, there was something special in people, and we felt happy there. We savored the unimaginable, but the best of the food in Brunei is not the taste, or cheap price, it is that people love it. What we have learned from Brunei is the love of food, any food, more or less simple, more or less special, they love the food, and then the food is good. It was also very easy with the help of the people of Brunei (you know).\nBrunei is a different country where foreigners feel at home. We don´t know why, but that is the truth.\n5. Food from which country interest you the most?\nWe have investigated the cuisine of eleven countries in East Asia, and all are interesting because the food of a country is its culture.", "297" ], [ "Brunei: Global Expeditions · Global Voices\nLike other citizens around the globe, Brunei is never short of people willing to take the challenge to put the country on the world map. Two sets of expeditions are being carried out.\n1. The Polar Girls\nThe blogger with the Polar Girls. Photo courtesy of <PERSON>\n<PERSON> reported on the fund raising walkathon for the two ladies known as the Polar Girls, to raise funds for their trip to Norway for training, where only one of them will be selected to join participants from seven other countries for the Commonwealth Women’s Antarctic Expedition. The women from Brunei, Cyprus, Ghana and Jamaica will be the first person from their nation to ski to the South Pole. They will brave blizzards, crevasses and temperatures below -30C as they ski over 800 kilometres across Antarctica to the Geographic South Pole. The formal launch of the expedition will take place on 10th March 2009.\n<PERSON> is currently taking time off from her studies in Bedford High School for the event.", "849" ], [ "The student who aims to be the “Asian lady version of <PERSON>” said that she wanted to participate in the event not only glorify Brunei, but also make history and make the most of the opportunity to participate in the worldwide event.\nDk <PERSON>, 25, is a civil servant at the Ministry of Foreign Affairs. Previously a secondary school mathematics teacher for three years, <PERSON> hopes that her involvement in the expedition would be able to raise Brunei’s awareness on global warming and climate change.\n2. Over the Horizon\nAs part of their efforts to commemorate 25 years of Brunei Independence, a husband and wife team, <PERSON> and <PERSON> and husband will undertake an epic expedition from March 2009 to October 2010, traversing Siberia/Russia/Mongolia and Kazakhstan/Iran/Syria on their way to Europe, reaching England after 25,000 km. They will continue southbound via France and Spain to Morocco and along the African West coast until Cape Town, South Africa. From there , they will ship the expedition vehicle to Buenos Aires Argentina; drive down to Ushuaia the last town before the Antarctica and cross the Americas on the long haul until Alaska, before returning to Brunei in October 2010.\nPhotos courtesy of Over the Horizon\n<PERSON> and <PERSON> are no strangers to global expeditions as they undertook a Trans Africa Journey from South Africa to Austria in 2007. <PERSON> was the first Bruneian to travel across 13 countries or 21,000km from Europe, Middle East to North Africa in a four-wheel drive in 1999. She also led a team of five local women to conquer Africa's Mt Kilimanjaro, the first Asian team to climb the world's highest volcanic mountain in 2001, to mark ‘Visit Brunei Year.’\nGood luck and make your country proud!", "849" ], [ "Brunei: Rainy days and flooding · Global Voices\nIt is the middle of the annual North-East Monsoon season and Brunei has been experiencing strong winds and rainfall. It was just ten days ago that part of the country was submerged by waters. Blogs, no doubt play an important role in informing the public on the state of the rain and the aftermath.\nIt was only ten days ago Iskandar World reported on the flood that has affected another district in the country, whereby his own home was affected by rising water levels.\nI was anticipating for a heavy down pour once I reach home…but nothing no rain and not even a drizzle..asked myself mana tia ujan nya ani!…baik tah ujan labat2..heheeh…Oh! boy..my wish sure comes true. Woke up in the middle and found my room nearly flooded (carpets & all the cushions soaked wet), hiya! apparently, the water seep in from the balcony..From midnite till 3am..I was buzy cleaning….damn!!!!!\n<PERSON> wrote that the rain is possibly, the impact from global warming.\nA perfect day that <PERSON> and <PERSON> got flooded – on the first day I return to work. Funny that we never seem to encounter these problem a decade ago. Either we are sinking or that global warming is taking its toll.\nHowever, last night's rain has caused much stand still to parts of the country. A main highway underpass tunnel in the capital and some schools were closed due to floods. It has caused diversion in traffic.\n<PERSON>, who was out on an errand trip, was caught in the rain downpour and stuck in traffic for a few hours.\nFinally after another hour or so, traffic started moving again, thanks to the traffic cops on duty.", "142" ], [ "All in all, what should have been a quick 30 minute trip became a 3 hour adventure!\nBruneiMotors, a blog that focus on car enthusiasts played good samaritans in informing the public on the state of the rain and areas that are affected by the floods.\n]The flash flood occured around 11.00pm to 3.00am on the night of 20/1/2009 and the Royal Brunei Police has block all the road that is unsafe for a motorist to pass through. They have done amazing job containing the serious area to avoid the road user from ruining their cars. Fire rescue and Ambulance are dispatch all around Brunei to monitor the safety of the public.\nBruneiLifestyle calls for a live traffic reports on radio to inform listeners on the current flood situation.\nI think its high time for the authority to set up a ‘live’ traffic report especially during the current wet spell and air them over all radio channels in every half an hour or so. Or why not make use of the Internet – after all Bruneians are IT-savvy lots. Video reports live through the handphones to your hands.\nThe blogger also believes that the current rain and flood is due to the effect of La Niña, with more thunderstorms expected until the end of this week:\nTranslated, La Niña means, “The Little Girl” , but sometimes she is called “El Viejo”, “anti-El Niño”, or even just “a cold event”. La Niña is characterized by cooling of waters in the central and eastern tropical Pacific Ocean and stronger than usual trade winds. It occurs almost as often as El Niño and also affects the normal weather patterns in some parts of the world, such as higher than normal rainfall in Southeast Asia.\nNo doubt bloggers become good samaritans in providing another medium to inform the public. Just like last year, Turqoise and Roses blogged about a flood in one of the districts in the country. Although reported in the local paper, she updated her blog live from the affected area several times in a day.\nThe recent event in Brunei do explain the regional phenemenon currently experienced, as reported by others bloggers on GVO on floods in Indonesia, Malaysia, the Philippines and Fiji,\nPhotos: courtesy of AnakBrunei, Iskandar World and BruneiMotors.", "142" ], [ "Southeast Asia: Ship of dreams and friendship · Global Voices\nTake a luxury cruise liner, fill it with some 300 vibrant youths from Association of Southeast Asian Nation (ASEAN) members and Japan, stir in cultural agenda and social interactions. The result: a strong bond and lifetime friendship. This is the story of the Ship for Southeast Asian Youth Programme (SSEAYP) or ‘Program Kapal Belia Asia Tenggara’ on the M. S. Nippon Maru, funded by Japanese government in fostering friendship between youths of ASEAN and Japan.\nAccording to BPY 2008, a blog dedicated to participants of last year's 35th SSEAYP, it is an annual youth programme that seeks:\n“to promote friendship and mutual understanding among the youths of Japan and Southeast Asian countries to broaden their perspective on the world, as well as to strengthen their motivation and abilities in international cooperation by participating in discussions, introductions of each country, and various exchange activities both on board and in the countries to be visited”.\nYouths on board take part in activities such as: discussion programs, solidarity group activities, club activities, giving of introductions about home countries, delivering and listening to lectures, and socialization activities. They act as mini ambassadors of their home countries as the ship stops at every Southeast Asian nation to give courtesy calls, attend receptions and participate in institutional visits. Some would get immersed into other cultures through homestays and interaction with local youths.\nTurqoise and Roses, one of the participants from Brunei shared her experience on the whole 52 days journey on the ship and the ports of calls. According to her, the experience was rewarding:\n‘We are indeed very lucky to be selected for the program and there is great emphasis on selecting the best of the best, as the real purpose of the ship is to learn. After participating, I definitely felt that friendship was very much enhanced, and many bonds were created.\nThe impact of the whole trip has been profound according to the blogger, that has allowed her to visit her fellow participants recently in Kuala Lumpur, Malaysia. She was able to make many official visits and courtesy calls through the programme that led to many chances of networking.\nI would certainly never have spoken to the owner of the Vietnamese factories if I was not in the programme. Who knows…. one day I want some investors, I know just who to contact.", "696" ], [ "My friends, who were young entrepreneurs were very excited for this aspect of the programme.\nAlso the homestay was phenomenal. In Indonesia, she stayed with an inspiring politician who raised her kids alone after her husband died. In Bangkok, it was this really rich man who manages a Thai bank who really taught her a lot!\nI could never imagine that kind of friendship without the programme. It is difficult for us to part. Memang payah kan becarai!!!!!! Kalau bulih kami ani mesti tah bejumpa setiap hari. Cerita nda pandai habis eventhough we've been spending the last 6-7 months together???\nDifficult for us to part. If possible, we must meet everyday. We can never finish sharing our stories eventhough we've been spending the last 6-7 months together???\nM.S Nippon Maru sets sail for the last time before making way for a new ship next year.\nBrunei's involvement started in the early 1980s first as an observer, then as actual participant. Every country is given a quota of 28 participating youths (PYs) consisting of 14 girls and 14 boys, and 1 national leader (NL). To join the program, each country has different criteria. For Brunei, you need to be single, between 18-30 years of age, preferably active in any youth based activities/organizations, and has talent in the performing arts.\nThis resulted in setting up of an alumni network, as in the case of Brunei, ‘BERSATU’ which means in English, together. Bersatu, is one of the local NGOs or youth organisations that:\ngreatly signifies the dynamic spirit of Brunei Darussalam ex-participating youth (ex-PYs) in their true aim of fulfilling the SSEAYP Objective of strengthening existing friendships with their young contemporaries in the other nine ASEAN countries and Japan.\nI found reading her experience to be a truly\nAMAZING EXPERIENCE!!! <PERSON> is the ship of dreams!\nStories like this no doubt bond youths and most importantly create a greater understanding between different cultures, religion and societies as well as the future leaders of ASEAN and Japan together!\nPhotos in this post courtesy of BPY 2008", "1010" ], [ "Brunei: Fund drive for flood victims · Global Voices\nThe heavy downpour last month caused heavy floods and landslides in the country, affecting homes of more than 200 families, leading to loss of milllions in property and crops in all the four districts in the country. This has made the community to come together to pledge help for the less fortunate and those affected by the natural disaster.\nA public fund to help the victims from the recent flood and landslide was set up by the Ministry of Home Affairs on 3rd February 2009. The intention is to help ease some of the difficulties faced by the victims in getting back to their normal life. As part of the efforts to collect donation to this fund, charity drives have been organized in recent weeks for the benefit of the National Fund for the Flood and Landslide Victims. This is an example of how resilient the local community in helping one another. Masyarakat Perihatin is a Malay phrase which means a caring society.\nFor example, the Orchid Garden Hotel spearheaded a cupcake charity.", "365" ], [ "The hotel succeeded in selling more than 2,000 cupcakes. It proudly displayed a 25-tiered cake made up of 250 kg of cupcakes. The whole structure measured seven feet by seven feet wide and 16 feet tall.\nPhoto by Strictly Beautiful\n<PERSON> reported about the cupcake charity event and another fund drive which sold 900 coupons of Nasi Lemak, a popular local dish:\nThe Cupcake charity at The Orchid Garden Hotel managed to sell 2,000 cupcakes. That’s amazing numbers. Another charity event was held at D’ Other Office Cafe and Bistro, where almost 900 coupons of Nasi Lemak ( local rice dish cooked in coconut milk) and Egg Tart combined was sold to the public.\nPhotos courtesy of <PERSON>\n<PERSON> reported on the charity football event which gathered at least B$100,000:\nMatch between DPMM FC and FFBD XI. The match was organized by the Football Federation of Brunei Darussalam . All proceeds (nearly B$100k from what I gather) will be donated to the Fund for Flood and Landslide Victims\nThe picture above shows His Royal Highness <PERSON> , chairman of DPMM Football club handing over the money collected from the football charity drive to the chairman of the Flood and Landslide Victims Fund.", "365" ], [ "Brunei: Think Big ICT Business Plan Competition · Global Voices\nAs part of the efforts to nurture new IT companies, Brunei Economic Development Board (BEDB) recently organised a Think Big business plan competition,\nlaunched in August 2008, offers the largest cash prize awards of its kind in Brunei Darussalam. The main aim is to motivate local entrepreneurs to realise their ideas in the field of information and communications technology (ICT) with the opportunity to develop their business ideas and enhance their creativity; as well as to provide a platform for identifying, nurturing and showcasing entrepreneurial talents in Brunei. This competition also provides the participants access to global resources and the entrepreneurial process through workshops and mentoring programme.\n39 ICT enthusiasts including 7 iCentre incubatees with background ranging from online games and shops, online malls and schools, portal, social networking, mobile applications to enterprise solutions.", "696" ], [ "RanoAdidas, one of the well-known local blogger and finalist in the competition, sees\nthe judges are pretty tough as well and it’s like a simulated pitch to real investors and venture capitalists (VC). This exercise has given me more experience and also the confidence to pitch to potential investors one day. I hope iCentre will continue this competition to encourage more participants and of course, encouraging more entrepreneurs.\nAs reported by AnakBrunei, the winners are:\n* Winning the ICT Business Plan category was Brumesh by Rafiqun WDSI with cash prize of $20,000;\n* YouGotSnapped by Expansys Technology in the second place with cash prize of $10,000;\n* Outsource Contact Centre by 24-7 Assist in the third place with cash prize of $5,000.\n* the Special Islamic Merit Award for Islamic Application was given to Mimit e-Technology with a cash prize of $2,000.\nInteresting enough, three of the winners have also recently inked separate deals with Philippine-based Crestar Communications, which will provide the platform for the iCentre firms to tap into the Philippine ICT market, as reported by the Brunei Times.\n<PERSON>, Crestar chief executive, said the collaboration with the iCentre companies is a defining step towards the realisation of Brunei's goal of becoming a hub for ICT in the Bimp-Eaga region.\nExpansys Technologies aims to launch its text or short messaging system gateway technology as the preferred platform in delivering the integrated systems of Mesh, IPTV and GPS technology in the Philippines.\nMimit e-Technology intends to launch its V-track system, a global positioning system tracking system for fleets as well as e-ilmu, an Islamic mobile content application developed for the Muslim communities in the Philippines.\nRafiqun WDSI plans to deliver its Wireless Mesh Device and IPTV to serve the Philippines market.\nThey will also be bringing in their expertise in wireless design, e-commerce and e-government consultancy services to the country.\nCongratulations to those winning IT companies that are going regional! Hope this will serve an inspiration for other new IT companies or SMEs that are thinking of venturing regionally!", "696" ], [ "Digital discourse: How going online is keeping Kadazan and other indigenous languages alive in Borneo · Global Voices\nPhoto provided by <PERSON> and used with permission.\nEditor's note: From April 14-20, 2021, <PERSON> will be hosting the @AsiaLangsOnline rotating Twitter account, which explores how technology can be used to revitalize Asian languages. Read more about the campaign here.\nWhen <PERSON> was working on her graduate school thesis, she observed code-switching (the practise of alternating between two or more languages or varieties of language in conversation) within an indigenous Kadazan family in Malaysia. As a Kadazan herself, she immediately saw her own experience reflected in this “passive bilingualism,” in that she could understand the Tangaa’ or coastal Kadazan language, but she could not speak it, as was the same with many local people. While it frustrated her that she could not speak her language, it also motivated her to continue to learn and support other language communities in the state of Sabah in Borneo, Malaysia.\nTogether with mentors and supportive friends, the motivation led to the setup of the Research Unit for Languages and Linguistics of Sabah at Universiti Malaysia Sabah. The unit then joined the Borneo Research Institute for Indigenous Studies (BorIIS) as the Languages and Linguistics Cluster. The Institute is exploring different strategies to revitalize local languages. It recently held a webinar with Wikimedia Indonesia and the Indonesian Language Planning Agency on the topic of “Sustaining Indigenous Languages through the use of Wikimedia projects”. It has also contributed resources for the Endangered Languages Project’s COVID-19 Information on Indigenous, Endangered, and Under-Resourced Languages, with the creation of posters in Kadazandusun, Kadazan, Dusun, Rungus, Kimaragang, Tobilung, Murut, and Bajau languages.\nRising Voices (RV): What is the current status of your language offline, as well as online?\n<PERSON> (JS): Offline, if you go by the Expanded Graded Intergenerational Disruption Scale (EGIDS), Kadazan is considered as 6b – Threatened. Ethnologue reports the size and vitality of Kadazan as ‘Endangered’ with that red color, which means it is no longer the norm for children to learn and use this language.\nIt is present online in one form or another. There are several Facebook groups that use a ‘Let’s Learn’ concept, where the members support each other by conversing in the language.", "811" ], [ "Most recently, there has been active input online from the local Sabah Cultural Board on their social media platform. That is a positive development, especially when they involve the ethnic bodies or associations and the youths. There used to be an online version of a local newspaper that has indigenous language news columns, but sadly no more. The indigenous language page on another local daily also finally stopped last year.\nMaterial-wise, in my opinion, Kadazan is quite [far] ahead compared to the other indigenous languages, in that it already has several printed dictionaries. There is also a dedicated radio channel in the language.\n<PERSON>: What do you think are the biggest challenges facing your language community when it comes to digital communications or creating digital content in their mother language?\n<PERSON>: In my opinion, the biggest challenge would be perhaps in getting sustained interest [from the audience] to view digital content in indigenous languages, and for digital content creators to be motivated to continue creating digital content in the indigenous language.\nDigital content creators are many, but a glance on YouTube shows sporadic uploads. I believe this is also because digital content needs audience for feedback and to motivate the content creators. Is there interest from the indigenous communities to hear or see their indigenous languages online? This is perhaps a question that the indigenous communities need to ask themselves because language champions cannot work in a vacuum, we need the indigenous communities too to be interested to champion their languages, to want to sustain their languages, and together, the collaboration will then be more successful, offline or online.\nThat is [when] we are talking about local indigenous viewers. On another hand, digital content need not be limited to just local viewers/audience from your neighborhood. The netizens of the world are [a] potential audience. If you make your content interesting and you have subtitles in English (or whatever language you aim to have viewers from), netizens from all over the world will be able to engage with your material.\nHaving said [this], digital content creators need good internet access, and especially in the rural areas where families are still using the indigenous language in their home as their first language (L1). So these challenges can be in the form of sustained interest, translation capacities, as well as internet access.", "507" ] ]

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[ [ "I finally found a way to obtain these velocities with calculus. I am sure that one can always try to deduce the particles velocities by mere logic; in fact, more than once, I \"thought\" about the answer that I finally found. But I was not comfortable without a calculus development.\nFinding the velocity of particle 1\nWe can first calculate the velocity of the system center of mass by taking particle 1 as a reference.\n\\begin{equation} \\vec{v}_c = \\vec{v}_1 + \\dot\\theta\\vec{k} \\times \\frac{l}{2}\\vec{e}_r \\end{equation}\nwhere $\\vec{v}_c$ is the system center of mass velocity; $\\vec{v}_1$ is the total velocity of particle 1; $\\dot\\theta\\vec{k}$ is the angular velocity around an axis perpendicular to the $(x,y)$ plane; $\\times$ is the cross product operator ;and $\\vec{e}_r$ is the radial vector along the massless rod.\nWe know that particle 1 cannot have a vertical velocity because of the assumption of an inelastic collision.", "512" ], [ "So the equation above becomes:\n\\begin{equation} \\vec{v}c = \\vec{v}{1x} + \\dot\\theta\\vec{k} \\times \\frac{l}{2}\\vec{e}_r \\end{equation}\nwhere $\\vec{v}_{1x}$ is the horizontal velocity of particle 1. By developing the above equation, we end up with:\n\\begin{equation} \\vec{v}c = \\vec{v}{1x} + \\frac{l\\dot\\theta\\sqrt{2}}{4} \\left( -\\vec{i} + \\vec{j} \\right) \\end{equation}\nNow, if the system center of mass does not move horizontally, that means that the horizontal component of its velocity has to be zero. Consequently, in the above equation:\n\\begin{equation} \\vec{v}_{1x} - \\frac{l\\dot\\theta\\sqrt{2}}{4}\\vec{i} = 0 \\end{equation}\nand since the vertical velocity of particle 1 is simply zero, then:\n\\begin{equation} \\vec{v}_{1} = \\frac{l\\dot\\theta\\sqrt{2}}{4}\\vec{i} \\end{equation}\nFinding the velocity of particle 2\nThe velocity of particle 2 can now be simply calculated as:\n\\begin{equation} \\vec{v}_2 = \\vec{v}_1 + \\dot\\theta\\vec{k} \\times l\\vec{e}_r \\end{equation}\nand by developing the above equation :\n\\begin{equation} \\vec{v}_2 = \\frac{l\\dot\\theta\\sqrt{2}}{2} \\left( -\\frac{1}{2}\\vec{i} + \\vec{j} \\right) \\end{equation}", "804" ], [ "This question did not get up votes nor answers, maybe because as it turns out, this was not that complicated. In any case, I still propose a detailed answer just in case.\nSolving for $\\dot x$ and $\\dot \\theta$\nThe impulse applied on top would be defined as the variation in the linear momentum of the particles system. For more convenience, we will be using particle $B$ as a reference point.\n\\begin{equation} \\hat{\\mathbf{J}} = \\sum\\limits_{i=1}^{3}\\Delta \\mathbf{p_i} \\end{equation}\nwhere $\\hat{\\mathbf{J}}$ is the total impulse vector affecting the system, comprised of the horizontal $\\hat{F}$ and the vertical constraint impulse $\\hat{N}$; and $\\sum\\limits_{i=1}^{3}\\Delta \\mathbf{p_i}$ is the sum of the linear momentum variation of the system particles.", "804" ], [ "Since the system is initially at rest, its particles initial velocities are null, so the linear momentum variation is simply the sum of their individual final momenta.\nBecause particles $A$ and $C$ are subject to a linear velocity $\\dot x$ resulting from the sliding of particle $B$; and to an angular velocity $\\dot\\theta$ resulting from the rotation about particle $B$; the above equation can then be developed as:\n\\begin{equation} \\left(\\hat{F}\\,\\vec{i}+\\hat{N}\\,\\vec{j}\\right) = m\\left( \\left( -l\\frac{\\sqrt{3}}{2}\\vec{i} + \\frac{l}{2}\\vec{j} \\right) \\times \\dot\\theta\\vec{k} + \\dot x\\vec{i} \\right) + m\\left( l\\vec{j} \\times \\dot\\theta\\vec{k} + \\dot x\\vec{i} \\right) + m\\dot x\\vec{i} \\end{equation}\nwhere $\\vec{i}$, $\\vec{j}$ and $\\vec{k}$ are unit vectors of the frame and the $\\times$ operator denotes the cross product between vectors. On the right hand side of the above equation, the first term corresponds to the linear momentum of particle $C$, the middle one corresponds to the linear momentum of particle $A$ and the last term is the linear momentum of particle $B$ which is only subject to a sliding motion.\nBy developing the above equation, the $\\hat{F}$ and $\\hat{N}$ components of the applied linear impulse vector $\\hat{\\mathbf{J}}$ are identified as the horizontal linear impulse applied on particle $A$:\n\\begin{equation} \\hat{F} = 3m\\dot x + \\frac{3}{2}m l \\dot\\theta \\end{equation}\nand the constraint linear impulse applied by the supporting base on particle $B$:\n\\begin{equation} \\hat{N} = \\frac{\\sqrt{3}}{2}m l \\dot\\theta \\end{equation}\nSince the constraint linear impulse $\\hat{N}$ is considered a consequence of the linear impulse $\\hat{F}$ and the value of $\\hat{N}$ is unknown, we still need one equation to solve for the $\\dot x$ and $\\dot \\theta$ values. Keeping particle $B$ as the reference point for the angular momentum of each particle, we can find $\\dot x$ and $\\dot \\theta$ without having to solve for $\\hat{N}$. Thus, we can state a relationship between the angular impulse at $B$ resulting from the linear impulse on particle $A$ and the variation of the angular momentum of each particle:\n\\begin{equation} \\hat{\\mathbf{M}} = \\sum\\limits_{i=1}^{3}\\Delta \\mathbf{H_i} = \\sum\\limits_{i=1}^{3}\\mathbf{r}_i \\times \\Delta \\mathbf{p_i} \\end{equation}\nwhere $\\hat{\\mathbf{M}}$ stands for the angular impulse around particle $B$ of the linear impulse $\\hat{F}$ applied on $A$; $\\sum\\limits_{i=1}^{3}\\Delta \\mathbf{H_i}$ represents the sum of the individual angular momenta around $B$ of particles $A$ and $C$; and $\\mathbf{r}_i$ is the vector going from $B$ to the other particles.", "804" ], [ "Impulse and momentum on a system of three particles (equilateral triangle)\nI found this exercise on a textbook which provided solely the description of what is happening and the answers with little explanation. The solution being provided, I am mostly interested in understanding what is happening. Consider the following system composed of three particles, each of mass $m$, connected by rigid massless rods in the form of an equilateral triangle. The system is initially at rest (particle $A$ is above particle $B$ in the initial state). An impulse $\\hat{F}$ is applied to $A$, causing the particle $B$ to slide without friction on a supporting base.\nThe idea is to solve for the values of $\\dot x$ and $\\dot \\theta$ velocities immediately after the impulse; and evaluate the constraint impulse $\\hat{N}$.\nMy initial idea was to use the linear impulse, focusing in the $x$ direction first.", "512" ], [ "Since particle B will be sliding, the linear acceleration of the system would be $3m\\ddot x$. By taking particle B as the reference point, and since the system center of mass would be engaged in an arc motion, its acceleration $x$ component (tangential) directly after the impulse would be $ml\\sqrt{3}\\ddot\\theta$ (the radius would be $l/\\sqrt{3}$).\nSo the impulse would be $\\hat{F}=3m\\dot x+ml\\sqrt{3}\\dot \\theta$.\nBut the textbook solution indicates that $\\hat{F}=3m\\dot x+\\frac{3}{2}ml\\dot \\theta$.\nSo my first problem is: where does the $\\frac{3}{2}$ comes from? Or am I working this completely wrong?\nUpon seeing this solution I wondered if perhaps this $\\frac{3}{2}ml\\ddot \\theta$ tangential component of angular acceleration would be the result of the addition of an $l/2$ radius (along the vertical axis) which would be the vertical distance towards particle C from B; plus the $l$ radius which would be the vertical distance towards particle $A$; multiplied by $\\ddot \\theta$. Which would result in a \"tangential\" component along the $x$ axis of $\\frac{3}{2}ml\\ddot \\theta$. Would this be an acceptable proposition?\nMy idea was then to state the angular impulse as the variation of the angular momentum, resulting in the multiplication of $\\hat{F}$ by the distance between particle $B$ and the center of mass: $l/\\sqrt{3}$. This way I would end up with a system of two equations and two variables and solve for $\\dot x$ and $\\dot \\theta$.\nOnly, again the solution provided is rather far from my idea because it states that $\\hat{F}l = \\frac{3}{2}ml\\dot x + 2ml^2\\dot \\theta$. And I see little relationship with the linear impulse equation.", "101" ], [ "Cube bouncing off a wall\nAn elastic cube sliding without friction along a horizontal floor hits a vertical wall with one of its faces parallel to the wall. The coefficient of friction between the wall and the cube is $\\mu$. The angle between the direction of the velocity $v$ of the cube and the wall is $\\alpha$. What will this angle be after the collision (see Figure P.1.3 for a bird's-eye view of the collision)?\nThis is Problem 1.3 in A Guide to Physics Problems, Part 1: Mechanics, Relativity, and Electrodynamics. There are things I don't understand in the solution provided in the book.\nThere are two forces acting on the cube. One is the normal reaction $N(t)$, perpendicular to the wall, and the other is the force of friction $F_{fr}(t)$ parallel to the wall\nWe expect that, as a result of the collision, the cube’s velocity $\\textbf v$ will change to $\\textbf v'$. In the direction perpendicular to the wall, the collision is elastic, i.e., the velocity in the $\\textbf{x}$ direction merely changes sign: $v'_x=-v_x=-v\\sin(\\alpha)$.", "512" ], [ "Therefore, the momentum changes by $-2mv\\sin(\\alpha)$ in the $x$ direction. This change is due to the normal reaction $N(t)$\nSo, according to <PERSON>’s second law: $$\\Delta p_x = -\\int_0^\\tau N(t) dt = -2mv\\sin(\\alpha)$$\nwhere $\\tau$ is the collision time. If there were no friction, the parallel velocity component would not change and the angle would remain the same. However, in the actual case, the $y$ component changes and $$\\Delta p_y = -\\int_0^{\\min(\\tau',\\tau)}F_{fr}(t)=-\\int_0^{\\min(\\tau',\\tau)}\\mu N(t) dt$$\nHere $\\tau'$ is the time at which the velocity $v_y$ goes to $0$. So $$mv_y'=mv_y -\\int_0^{\\min(\\tau',\\tau)}\\mu N(t) dt$$\nThe first thing I can't grasp is why the collision is elastic in the $x$ direction. Admitting this, I'm ok with the equation $\\displaystyle \\Delta p_x = -\\int_0^\\tau N(t) dt = -2mv\\sin(\\alpha)$.\nBesides, I don't get why $\\displaystyle \\Delta p_y = -\\int_0^{\\min(\\tau',\\tau)}F_{fr}(t)$. It looks a lot like the previous equation the author got on the $x$-axis, but I don't understand why he considers $\\tau'$ as the time at which the velocity $v_y$ goes to $0$, and why the upper bound of the integral has to be $\\min(\\tau',\\tau)$.", "512" ], [ "I'd like to point out here that the expression «$\\vec{a}=d\\vec{v}/dt=\\vec{v} d\\vec{v}/dx$» is not entirely senseless.\nIn the definition\n$$ \\vec{a} = \\frac{d\\vec{v}}{dt} $$\nvelocity is considered to be the function of time $\\vec{v} = \\vec{v}(t)$ because we follow an individual particle along its trajectory. So in this case the expression is wrong.\nBut if you look at a continuous system of particles e.g.", "359" ], [ "flowing water, you can define the velocity to be a function of time and coordinates $\\vec{v} = \\vec{v}(t, x, y, z)$ - it would be equal to the velocity of a small droplet of water that happened to be in point $(x,y,z)$ at time $t$. As time goes by, this droplet would move to a different point in space $(x',y',z')$ , while another droplet would take its place at $(x,y,z)$ and so on. The $\\vec{v}(t,x,y,z)$ is called \"velocity field\".\nTo calculate the acceleration of an individual droplet in this case, you should compare droplet's velocity at time $t$\n$$ \\vec{v}_d(t) = \\vec{v}(t,x,y,z) $$\nwith the velocity it will have at time $t+dt$ having moved in space by $\\vec{v}_d(t)dt$:\n$$ \\vec{v}_d(t+dt) = \\vec{v}\\left(t+dt, x+v_x(t,x,y,z)dt, y+v_y(t,x,y,z)dt, z+v_z(t,x,y,z)dt\\right) $$\nExpanding this you get\n$$ \\vec{v}_d(t+dt) = \\vec{v}_d(t) + \\vec{a}dt = \\vec{v} + \\left(\\frac{\\partial\\vec{v}}{\\partial t} + v_x \\frac{\\partial\\vec{v}}{\\partial x} + v_y \\frac{\\partial\\vec{v}}{\\partial y} + v_z \\frac{\\partial\\vec{v}}{\\partial z}\\right)dt $$\nso finally the acceleration is\n$$ \\vec{a} = \\frac{\\partial\\vec{v}}{\\partial t} + v_x \\frac{\\partial\\vec{v}}{\\partial x} + v_y \\frac{\\partial\\vec{v}}{\\partial y} + v_z \\frac{\\partial\\vec{v}}{\\partial z} $$ which is close to your original expression, but rather be written as\n$$ \\vec{a} = \\frac{\\partial\\vec{v}}{\\partial t} + (\\vec{v} \\cdot \\frac{\\partial}{\\partial \\vec{r}})\\vec{v} $$", "766" ], [ "Suppose your table or ship is supported by forces $\\vec F_i$ applied at $N$ fixed points. In general, there are two vector equations you need to solve. In order for the ship to remain suspended, the net force on it must be zero:\n$$\\sum_i \\vec F_i=-\\vec G$$ where $\\vec G$ is the weight. In addition, the net torque must be zero so that the table/ship does not rotate: $$\\sum_i \\vec r_i \\times \\vec F_i = 0.$$ where $\\vec r_i$ are the positions at which the forces are applied, relative to the center of mass (which I'm assuming is the same as the center of gravity, i.e. the gravitational field is uniform). $\\times$ here denotes cross product.\nIf all forces are in the same (vertical) direction, the equations you need to solve can be simplified somewhat. Namely, if $\\vec F_i = F_i \\hat z$ and $\\vec G = -G\\hat z$, $$\\sum_i F_i=G$$ $$\\sum_i x_iF_i=0 $$ $$\\sum_i y_iF_i=0 $$\nNote that this is a linear system of three equations.\n1. For $N = 1$, there is an \"unstable\" solution if and only if $\\vec r_1=0$, i.e. the force is applied at the center of mass.", "766" ], [ "The solution is unstable in the same sense as a one-legged table.\n2. For $N=2$, there is an \"unstable\" solution if and only if the center of mass lies on the line connecting $\\vec r_1$ and $\\vec r_2$ (i.e. $\\vec r_1$ and $\\vec r_2$ are colinear with the center of mass). The solution is unstable in the same sense as a two-legged table.\n3. For $N=3$, there is a unique, stable solution as long as no two of the points $\\vec r_1$, $\\vec r_2$ and $\\vec r_3$ are colinear with the center of mass. If you further require that all forces $F_i$ be non-negative, the center of mass must lie in the interior of a triangle defined by $\\vec r_1$, $\\vec r_2$ and $\\vec r_3$ as its vertices.\n4. For $N\\ge4$, except possibly in degenerate cases (where some pairs of \"vertices\" are colinear with the center of mass), there are infinitely many solutions (i.e. no unique solutions).\nA four-legged table with each leg in contact with the ground doesn't actually need to be supported by equal forces applied at each leg. All that is required (besides the condition that the sum of the forces equal the weight) is that the forces on opposite legs be equal. So there are an infinite number of force distributions that will support the table.", "151" ], [ "... my question is why can we use <PERSON>'s rotational second law in $P$'s frame? The point $P$ of contact moves (indeed, accelerates, with time). I suppose that, at an instant of time, we can consider $P$ as the point on the fixed ground which is in contact with the disk.\nWhen in doubt, be careful; assumptions here do not appear as they seem.\nLet $\\textbf{r}{\\text{s}}$ be the vector connecting our lab frame to some other stationary frame of reference, and let all positions in the lab frame $\\textbf{r}_i$ be represented as $\\textbf{r}\\text{s} + \\textbf{δ}i$, where $\\textbf{δ}_i = \\textbf{r}_i - \\textbf{r}\\text{s}$.\nAngular momentum of a body, in that other frame of reference, is defined by $$\\textbf{L} = \\int_{\\,V}\\textbf{δ}{dm} \\times (\\dot{\\textbf{δ}}{dm}\\, dm) = \\int_{\\,V}(\\textbf{r}{dm} - \\textbf{r}\\text{s})\\times\\dot{\\textbf{r}}_{dm}\\,dm$$\nWith that in mind, let's examine the validity of switching stationary frames.", "101" ], [ "For constant different $\\textbf{r}_\\text{s}$, it might be of value to find the geometric shape such that $\\textbf{L}$ remains invariant.\nThen the angular momentum, for different $\\textbf{r}\\text{s}$, becomes $$\\begin{align} \\textbf{L} &= \\int{\\,V}(\\textbf{r}{dm}\\times\\dot{\\textbf{r}}{dm})\\,dm - \\int_{\\,V}(\\textbf{r}\\text{s}\\times\\dot{\\textbf{r}}{dm})\\,dm \\ &= \\int_{\\,V}(\\textbf{r}{dm}\\times\\dot{\\textbf{r}}{dm})\\,dm - \\textbf{r}\\text{s}\\times\\left(\\int{\\,V}dm\\right)\\left(\\frac{\\int_{\\,V}\\dot{\\textbf{r}}{dm}\\,dm}{\\int{\\,V}dm}\\right) \\ &= \\int_{\\,V}(\\textbf{r}{dm}\\times\\dot{\\textbf{r}}{dm})\\,dm - \\textbf{r}\\text{s}\\times M\\dot{\\textbf{r}}\\text{CM} \\ \\end{align}$$\nDue to the cross product, the endpoints of $\\textbf{r}\\text{s}$ that correspond to the same $\\textbf{L}\\,$ effectively draws a line parallel to whichever direction $\\dot{\\textbf{r}}\\text{CM}$ points in.\nHence, if we were to consider a disk rolling down a slope, we can set the endpoints of $\\textbf{r}\\text{s}$ to sit on the contact points the disk rolls through, since this is a straight line. As the disk rolls by each endpoint, we can peer in each stationary frame and safely analyze the torques and forces as expected, in a snapshot of time; the contributions $\\dot{\\textbf{L}}=\\textbf{Γ}$ considered correspond to a commensurate change in the same angular momentum across our stationary $\\textbf{r}\\text{s}$ vectors.\n$$\\rule[0]{300pt}{0.4pt}$$\nIt's important to note that if the endpoint of $\\textbf{r}s$ is legitimately translating along with the contact point of the disk, then the angular momentum obtained is different from the angular momentum we analyzed through jumping across stationary frames—we must take into account $\\dot{\\textbf{r}}\\text{s} \\neq 0$, and the equivalence between $\\dot{\\textbf{L}}$ and $\\textbf{Γ}$ is not quite true.\n... the result holds only in an inertial frame precisely because <PERSON>'s second law has been invoked (with the standard \"coincidence\"/exception of the result holding in the CM frame being noted).", "804" ], [ "What's the Lagrangian for a freely rotating rod?\nThis is one of those problems that I thought would be easy, then spent forever on it and realized that I know nothing:\nA rigid rod of uniform density has mass $M$ and length $L$ and is free to rotate about its center without a fixed axis. Consider its center to be fixed at the origin of an inertial Cartesian coordinate system, and note that the position of the rod can be specified with the spherical coordinate angles $\\theta$ and $\\phi$. (Also assume zero gravity.)\n1. What is the Lagrangian of this system, in terms of the coordinates $\\theta$ and $\\phi$?\nFirst, I calculated the moments of inertia for rotation in the pure $\\theta$ and pure $\\phi$ directions. For $\\theta$, this is the usual $\\frac{1}{12}ML^2$, but $\\phi$ it becomes $\\frac{1}{12}ML^2\\sin^2\\theta$ assuming the rod is held at fixed $\\theta$.", "101" ], [ "Then I used $K_{rot}=\\frac{1}{2}I\\omega^2$ for each type of rotation and added the two:\n$$\\begin{align} L &= K-U \\ &= K_\\theta+K_\\phi-0 \\&= \\frac{1}{24} M L^2\\dot\\theta^2+ \\frac{1}{24} M L^2\\sin^2(\\theta) \\,\\,\\dot\\phi^2 \\end{align}$$\nMy main concern is that adding the two energies doesn't seem justified, so my next question is:\n1. If this is correct, why is adding these two energies justified?\nTo emphasize the concern, consider this: pure $\\theta$-rotation corresponds to $\\vec\\omega$ in one direction, while pure $\\phi$-rotation corresponds to $\\vec\\omega$ in another direction. These two vectors span only a plane, whereas in general $\\vec\\omega$ could point anywhere in 3D space, so it isn't at all clear that these angular coordinates simply \"add\" in a straightforward way.\nTrying to find the answer more rigorously, I calculated the inertia tensor (assuming at time $t=0$ the rod is lying in the $z$-$x$ plane) and tried to use $K_{rot}=\\frac{1}{2}\\vec\\omega \\cdot (\\tilde{I} \\vec\\omega)$. This leads to my final and most deceptively difficult question:\n1. What is $\\vec\\omega$ in terms of $\\theta$, $\\dot\\theta$, $\\phi$, and $\\dot\\phi$?\nAlso if there is a cleaner or more straighforward approach for solving this problem, I'd love to know about it!", "101" ] ]

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[ [ "Recent troubles rock the historical Kano Kingdom in northern Nigeria · Global Voices\nThe Emir of Kano, <PERSON>, at Durbar Festival celebrating Eid in June 2018, Kano, Nigeria. Photo by <PERSON> via Wikimedia: CC BY-SA 4.0.\nThe Kingdom of Kano in northern Nigeria is in trouble.\nGovernor <PERSON> of Kano State in northwestern Nigeria, has decided to split Kano Emirate into five distinct territories, breaking up a kingdom that has existed before the age of governors for nearly 1,000 years.\nDating back to the year 999 as one of Nigeria’s largest kingdoms, Kano played a central role in trans-Sahara commercial routes. Kano is home to a remarkable museum that holds ancient relics in a prominent palace, and Nigerians often gather for festivals and exhibitions.\n<PERSON>’s decision to split this ancient kingdom under his governance is tied to a political tug-of-war between himself, Kano’s former governor, <PERSON> and the current king, 57-year-old Emir <PERSON> , the 58th Emir (King) to date — appointed by <PERSON> before his term ended.\nOnce political allies, <PERSON> and <PERSON> became rivals after <PERSON> took office in 2015, and now his decision to split <PERSON>’s kingdom is, according to some, an act of revenge against the emir, his rival <PERSON>'s pick.\nThis adverse situation has disturbed the unity among Kano Kingdom households who have gotten along for centuries.\nCounting from the unification in 927, the British Monarchy is about 1,092 years old. Kano Kingdom was founded in 999, 1,020 years old.\nWhile the Brits will do all to uphold the dignity of their royal heritage, Nigeria is dismantling its own heritage over petty politics. Thread.\n— <PERSON> (@AyoBankole) May 8, 2019\nOn May 10, the courts instructed <PERSON> to halt the appointment ceremony of the new kings, but he defied the court and executed the division anyway, claiming he was carrying out the orders of the state legislature .\nSeveral palace officials decried Governor <PERSON>’s actions, calling it a distortion of a working model for governance in Kano and northern Nigeria. <PERSON> said he did not obey the court order because it came after the appointment of the new emirs in each of the five distinct sub-kingdoms: Kano, Rano, Karaye, Gaya and Bichi.\nHowever, on May 15, the court ordered a return to the status quo pending the hearing of the suit against the appointment of the new emirs.\nMany Kano residents, depressed by the division, said Governor <PERSON> is playing politics in diminishing the famous Kano Kingdom.\nThe Emir of Kano on his throne, September 2016.", "1017" ], [ "Photo by <PERSON> via Wikimedia: CC BY-SA 4.0.\nPolitical rivalry\nCurrent Governor <PERSON> worked as deputy governor to <PERSON> twice between 2011 and 2015.\nWhen <PERSON> was about to leave office, he called on <PERSON> as his deputy to run in the 2015 election. But since <PERSON> took office, <PERSON> has accused him of not being loyal, although <PERSON> denies these charges.\nDuring Nigeria’s 2019 presidential election, <PERSON> strategized to prevent <PERSON> from taking on a second term, but <PERSON> prevailed.\n<PERSON> has expressed hostility toward <PERSON> for supporting <PERSON>’s favored candidate, <PERSON>, of the People’s Democratic Party, during the 2019 election.\nThe two rivals have challenged each other with political blackmail through their supporters. <PERSON> has revoked all <PERSON>’s projects that he started as governor.\n<PERSON>’s move to split the kingdom is revenge against <PERSON>’s partisanship and another way to show disdain for <PERSON>.\nHe says the five new territories would operate as Kano’s sub-domains within Kano State. Jurisdiction for these territories would fall under <PERSON> — instead of King <PERSON>.\nA history of kingmakers\nBefore 1903, kingmakers determined the pick of Kano kings through family lineage. But with Europe’s widening influence in West Africa, ruling governors were given the power to choose kings beginning in 1903. Even though a prevailing democratic governor oversees Kano’s Emirate Council, it usually complies with ancestral customs of the kingdom.", "1017" ], [ "In Nigeria, tensions rise in Kano Kingdom as king faces finance corruption charges · Global Voices\nKing <PERSON> of Kano Kingdom sits on his throne in the palace, Kano state, Nigeria, September 2016. The king now faces serious allegations of financial corruption and misuse. Photo by <PERSON> via Wikimedia Commons: CC BY-SA 4.0.\nAn atmosphere of gloom settled over the ancient city of Kano in northern Nigeria, as the Kano State Public Complaints and Anti-Corruption Commission investigated King <PERSON> , the Emir of Kano Kingdom, for financial scandals that date back to 2017:\nMore trouble for Emir <PERSON> as Kano anti-corruption agency unveils 5 heavy allegations against Emirate Council https://t.co/Yt2CrP1wGK\n— <PERSON> (@Awevooty) June 6, 2019\nKing <PERSON> of Kano Kingdom in northern Nigeria. Photo by <PERSON> via Wikimedia Commons, March 2017, CC BY SA 4.0.\n“As a government instituted agency, we [started] investigating these accusations since 2017 to date. We are still in the process.", "1017" ], [ "Code 9 promulgated by the Kano House of Assembly grants us the mandate to investigate all institutions under Kano State government. And Kano Palace is among others,” <PERSON>, chairman of the commission, told Global Voices in an interview on May 30, 2019.\nThe Kingdom dates back to the year 999 as one of Nigeria’s largest kingdoms and exists within modern Kano State under the jurisdiction of state Governor <PERSON> .\n<PERSON> has been at odds with King <PERSON> and made the controversial decision to break up the historic kingdom into five sub-domains, undermining the king's power.\nThe commission investigated King <PERSON> and three others — his palace chief of staff, <PERSON>, finance officer, <PERSON> and bookkeeper <PERSON> — for blowing nearly 3.4 billion Nigerian Naira (approximately $9,456,920 United States Dollars) since King <PERSON>'s coronation in 2014.\nThe commission released a report dated May 31 with five specific allegations lodged against the palace over misuse of funds between 2014-2017: They a warded illegal contracts to 21 shell companies; spent 117 million Naira to fuel generators ($325,481 USD); 54 million Naira expended on airtime and data ($150,210 USD); 105 million to an individual account ($292,075 USD); and 144 million Naira on hotel accommodation and flight tickets ($400,542 USD).\nKano govt queries Emir <PERSON> for allegedly misappropriating N3.4 billion https://t.co/FtF6sFVUQS pic.twitter.com/voQ1l9J6o6\n— SK (@introvert_king) June 7, 2019\n“…It is regrettable, and we further [see] that seven among these companies are not certified with the government,” <PERSON> said.\nBased on these findings, the commission recommended the suspension of <PERSON> and “all other suspects connected to this case … pending the final outcome of the investigation.”\nWhen Global Voices asked if the commission’s investigation into the king’s financial misdealing was a form of political prejudice, <PERSON> said this was a “false and mischievous accusation.” According to him, a few concerned individuals discovered the financial wrong-doing in Kano Palace and reported the king in 2017 — during that time, no hostility existed yet between the government and <PERSON>.\nTwitter user <PERSON> disagrees:\nIf there is any take away from the Gov <PERSON> vs Emir <PERSON> drama and <PERSON> generously withdrawing corruption allegations against Goje is that this corruption ‘fight’ is only a pressure weapon against political opponents. The more things change, the more they stay the same.\n— <PERSON> (@Moonchild509) June 8, 2019\nRead more: Recent troubles rock the historical Kano Kingdom in northern Nigeria\nImmunity for governors\nIronically, Governor <PERSON> himself is the subject of financial scandals, but Section 308 of the Nigerian Constitution restrains the commission from investigating the governor.\nYet, video footage circulating online shows <PERSON> allegedly collecting a bribe from state contractors in 2018. <PERSON> adamantly denied it.\nIn the year of our Lord 2019, <PERSON> wants to probe Sanusi for allegations of corruption ???. Wonders shall never end!pic.twitter.", "1017" ], [ "How Boko Haram Is Changing International Politics in Western and Central Africa · Global Voices\nAbuja, Nigeria. April 30, 2014. Protesters took to the streets around the three arms zones of Abuja to demand urgent action from the government in finding the 200 school girls kidnapped in Chibok. By <PERSON>. Copyright Demotix.\nTwo suicide attacks on June 22 in Maroua, northern Cameroon, left several people dead and many others wounded. Ten days earlier, 15 people were killed in a suicide bomb attack at a crowded market in N'Djamena, the capital of Chad. The attack came exactly three weeks after a similar bombing claimed the lives of 27 people in the same town.\nBoko Haram, a Sahel-based jihadist group that recently pledged allegiance to ISIS, claims responsibility for the attacks. The group struck again a few weeks after the June attacks, this time in Jos, Nigeria, killing at least 44 people. Boko Haram has repeatedly staged deadly attacks in the Sahel region for the past several years. In response, a coalition of West African countries came together to launch a military counterstrike in the hope of curbing the group's influence.\nBelow is a partial timeline of Boko Haram's offensive in 2015, which spread to Cameroon, Chad, Niger, and Nigeria.\nThe current situation in Cameroon\nAfter months of captivity by suspected Boko Haram militants, ex-hostages arrive at Cameroon's Yaounde Nsimalen International Airport. Public Domain via Wikimedia Commons.\nSince January 1, 2015, Boko Haram has carried out at least 28 major attacks on Cameroonian soil —most of them in the far north region. According to the local authorities in Maroua, the July 22 suicide bombings were carried out by two young girls who were seen begging in the streets in previous days. The explosion killed at least a dozen of people at the central market, but the exact number is still uncertain.", "90" ], [ "A security source confirmed that residents heard a double explosion.\nDespite these tragedies, the Cameroonian military has enjoyed some success against Boko Haram, though the country has also had to deal with the massive afflux of migrants fleeing the conflict.\nThe current situation in Chad\nChad Air Force Sukhoi Su-25 at N'djamena Airport CC-BY-4.0 license. Wikimedia commons.\nThe man who triggered a bomb on July 11 was disguised as a veiled woman to conceal the explosives. In light of this information, the government of Chad has decided to ban the veil to prevent similar attacks. The consequences of the Boko Haram insurgency have massively strained the region's stability, especially in Chad, whose military power was the foundation of peacekeeping in Sahel. In recent months, Chad has already been rocked by student protests and the June 20 start of the trial of former leader <PERSON>.\nThe current situation in Niger\n“Landscape Diffa region Niger” by <PERSON>. CC 2.0 via Wikimedia Commons.\nThe Boko Haram insurgency has forced tens of thousands across the border into Niger's arid southeastern region of Diffa, aggravating an already dire humanitarian crisis. The flood of refugees comes as Niger declares a state of emergency to tackle an insurgency that has brought Diffa's economy to a standstill and left much of the population vulnerable.\nThe current situation in Nigeria\nPrior to the March 2015 elections, the Nigerian Army had considerable gains in repelling Boko Haram. However, a renewed offensive by Boko Haram appears to be underway, ahead of the inauguration of President <PERSON>'s new government. This is despite the fact that one of <PERSON>'s first actions was to move the nation's command headquarters of the military from the capital Abuja to Maiduguri, in Borno State—a hotpot of the Boko Haram insurgency.\nReported explosion in #Gombe, northeast #Nigeria. No further details.\n— <PERSON> (@fidelisMbah) July 22, 2015\nNonetheless, the new government has pushed a great deal for international counterterrorist assistance, as evidenced by President <PERSON>'s recent meetings with the presidents of Chad, Cameroon, and Niger. <PERSON> has sought and received assurances of assistance from the G7 and the United States, where he is currently on a state visit. <PERSON> promised to negotiate with the insurgents, if that would lead to the release of the 200 abducted Chibok girls, kidnapped more than a year ago:\nIf we are convinced that we can have the girls, why not, we can negotiate. Our goal is to have the girls. We will ask them what they want and we can free the girls; return them to their school; unite them with their parents and rehabilitate them, so, they can live a normal life.\nThis post is co-authored by <PERSON>, <PERSON>, and <PERSON>.", "90" ], [ "The Houthi and <PERSON> Confrontation is Taking Yemen to a Dangerous Place · Global Voices\nMajor General <PERSON>, Minister of Defense the day he arrived arrived in Aden. Tweeted by @Yemen411 on March 8, 2015.\nAnother key member of Yemen's government has escaped the Houthi-controlled capital Sana’a in the north for the southern port city Aden. Defense Minister Major General <PERSON> arrived in Aden on March 8.\nThe Houthis, a ten-thousand strong tribal militia from the north, forcefully occupied the presidential palace in Yemen's capital city on January 21.\nSince they first entered Sana'a on September 21, 2014, the Houthis have taken over key government buildings, the airport, Yemen Central Bank, and income-generating national corporations like the Safar Oil Company.\nGeneral <PERSON>'s March 8 escape is seen as a big boost to President <PERSON>, who is building a rival power center in the south with loyal army units and tribes against the Houthis.\nOn March 7, a <PERSON> aide claimed the president said, “Aden became the capital of Yemen as soon as the Houthis occupied Sana'a.”\n<PERSON> escaped the capital Sana'a with his family after being under Houthi-imposed house arrest for a month.\n<PERSON> tendered his resignation a day after the Houthi took over his presidential palace. When he escaped and reached Aden, 400 kilometers away from the capital on February 24, <PERSON> released a statement saying Yemen’s parliament had not accepted his resignation, so he is still president. <PERSON> then denounced all political agreements made by the Houthis in Sana’a since they took over.\nAnti-Houthi voices celebrated <PERSON>’s prison break from Sana'a. Some worry that <PERSON> might have motivated the Houthis to invade Aden. And others believe <PERSON> is recklessly hijacking existing tensions between the north and south of the country.\nThe separatist sentiment remains popular in the south, where Yemenis feel economically and politically marginalized by the north. The Houthis belong to tribes from the north, and <PERSON> belongs to a southern tribe.\nBeing in Aden is symbolic and dangerous\nThe once-thriving coastal city Aden is Yemen’s second largest. Aden is the former capital of South Yemen, which was an independent state until 1990, when it unified with North Yemen.", "90" ], [ "Unhappy with Sana’a in 1994, South Yemen declared its secession again from the north. A civil war ensued, and the north ended up occupying the south.\nThe Houthis’ unilateral excessive use of power in Sana'a and our northern provinces has led the south to refuse any orders coming from them and they are organizing their own armies to defend themselves if the Houthis attack.\nThe Houthi populist movement\nThe Houthi uprising against the government started in 2004. Since then, Yemen's power center in Sana'a has alleged that the Houthis want to overthrow them and implement Shia religious law. The Houthis have maintained that they are “defending their community against discrimination” and government aggression.\nMost Houthis adhere to a branch of Shia Islam called Zaidism. Zaidis make up one-third of Yemen's population and ruled North Yemen for almost 1,000 years until 1962.\nYemen's government under previous President <PERSON> and current President <PERSON> has accused Iran of financing the Houthi insurgency. From 2004-2010, the government brutally tried to crush their rebellion.\nIn 2011, the Houthis joined a mass uprising against <PERSON>. They soon expanded their territorial control in Saadah and neighbouring Amran province.\nBefore September 21, 2014, no one in Yemen thought that the Houthis could possibly reach the capital Sana’a and no one thought that the Houthis would even consider waging a civil war that they were bound to lose.\nIt was shocking when Sana’a was surrounded by the Houthi militias. They demanded that subsidies on fuel prices stay in place.\nThey also promised to fight corruption and to implement the outcomes from the unprecedented National Dialogue Conference (NDC), which took place after the 2011 uprising in Yemen. This also helped fuel Houthi popularity.\nThe NDC was a 10-month deliberation process between <PERSON>, and representatives from the Houthis, political parties, and youth and women organizations. The conference was supposed to help Yemen transition fairly from 33 years of <PERSON> rule, but the various groups failed to reach consensus about addressing concerns of the south.\nWith the Houthis popularity and power increasing, President <PERSON> gave into their demand to set up a technocrat government.\nBut that wasn’t enough; they marched into Sana’a.", "90" ], [ "Kenyan TV Networks Censored for Airing Symbolic ‘Swearing In’ of Opposition Leader <PERSON> · Global Voices\n<PERSON> speaks at the 2013 World Economic Forum. Photo by WEF via Flickr (CC BY-SA 2.0)\nWhen Kenyan opposition leader <PERSON> was symbolically — if not legally — sworn in as the “people's president” on January 30, three major broadcasting networks were unplugged by the Government of Kenya.\n<PERSON> was sworn in for a second term as president on November 28, 2017 after winning a controversial re-run election, which was held in October 2017 after the country's Supreme Court annulled the results of the initial August 2017 vote, having found “irregularities and illegalities”. <PERSON> did not participate in re-run, arguing that systemic flaws that produced these irregularities had not been addressed. The elections were marked with protests, multiple incidents of violence and destruction of property.\nAfter months of uncertainty, incumbent president <PERSON> remains in power. But supporters of <PERSON> remain committed to his campaign and cause.\nOn January 30, 2018, thousands of Kenyans flocked to the famous Uhuru Park to witness a symbolic swearing-in ceremony for <PERSON> of the National Super Alliance (NASA). The majority of attendees were mainly people from Western, Nyanza, Coast and Eastern parts of Kenya where NASA enjoys sizable support.\n<PERSON> being “sworn in” as the Kenya's People's President [Screen shot taken on February 1, 2018]\nSome Kenyans did not go to work and decided they were going to watch this historic event from the comfort and safety of their homes. To their disappointment, the government decided to disconnect all the major broadcasting stations in the country including KTN News, Citizen TV and Inooro TV (both owned by Royal Media Services) and NTV, preventing them from effectively airing live coverage of the event.\nAccording to Kenya's Attorney general, the mock ceremony was “treasonous” and therefore, in their view, had no place on national television.\nThe Committee to Protect Journalists reported that President <PERSON> and other executive staff “summoned media managers and editors on January 26 and threatened to shut their stations down and revoke their licenses” if they proceeded with the broadcast.\nThis raised a loud uproar from civil society organizations and Kenyans in general from all walks of life and different political affiliations. The freedom of media is well-anchored in Kenya’s 2010 constitution, but this did not stop the <PERSON> government from denying Kenyans access to information\n‘People's president’ or ‘treasonous’ swearing in?\nWhile <PERSON> indeed does not hold the office of the President in Kenya, the ceremony at hand was more than just a show of support for <PERSON> and the NASA.\nIt came as the result of the People's Assemblies Bill, a motion tabled in all opposition-controlled counties that legalized “the formation of the people's assemblies in the devolved units”. The People’s Assemblies bill has been passed by at least 20 county governments out of 47.\nAccording to the People’s Assemblies bill, the power is vested in the people and their assemblies will have the power to recognize a leader of their choice.", "424" ], [ "Though this move by a select number of counties was perceived to be unconstitutional, it received substantial national support. The law also allows anybody of the capacity of a high court judge to administer the oath.\nMost of all I thank the good Lord, my family and all those who have undertaken this journey with us. We have arrived in Canaan; thank you for staying the course with us. <PERSON>. pic.twitter.com/6gdZBfxVAv\n— <PERSON> (@RailaOdinga) January 30, 2018\nThe swearing in ceremony of Mr. <PERSON> was meant to be held in 2017, but it was delayed due to a deep divide between <PERSON> and his core principals.\nIn the January 30 swearing-in ceremony, Mr. <PERSON>’s running mate, <PERSON> and other NASA core principles, <PERSON> and <PERSON>, did not turn up to the historic event. This kept <PERSON> waiting for too long, and infuriated the highly-charged crowd.\nWith advice from his key supporters, <PERSON> decided to take an oath of office as the people’s president in the absence of his running mate <PERSON> and other NASA principles. <PERSON> claimed they did not turn up at the Uhuru Park for the swearing in ceremony because their security guards were withdrawn by the state:\nI was left alone.", "1017" ], [ "For Opponents, WHO Director General Nominee <PERSON> Represents Ethiopia’s Repressive Government · Global Voices\nDr. <PERSON>, Minister of Health, Ethiopia, speaking at the London Summit on Family Planning in 2012. Photo by Flickr user UK DFID. CC BY-SA 2.0\nSome Ethiopians are fiercely campaigning against <PERSON>, Ethiopia’s candidate to replace <PERSON> <PERSON>, as director general of World Health Organization, just a few weeks before member states are set to vote on the final three candidates.\n<PERSON>, a former Ethiopian foreign and health minister, along with Pakistan’s <PERSON> and the UK’s <PERSON> are the three director-general nominees who made the cut from a larger pool of candidates in January.\n<PERSON>, who is running a well-funded campaign, is considered as a prime contender in the race. His candidacy was endorsed by the African Union, and just last week he picked up an endorsement of <PERSON>, the UK’s former international development secretary.\nHowever, he is facing unrelenting opposition from his own citizens.\nEthiopians who feel marginalized by their country's government are campaigning hard against him online, arguing he should not be elected because he represents the interests of Ethiopia’s autocratic ruling elites and not the people.\nThe irony is beyond tragic. The person who is responsible for the crimes against humanity in #Ethiopia is running for #WHODG! #NoTedros4WHO\n— <PERSON>@kiruskyy) April 28, 2017\nThey have set up online petition pages against <PERSON> and produced a documentary film detailing what they consider to be his failures and his alleged mismanagement of funds while he was Ethiopia’s health minister.\n<PERSON> presided and participated in the biggest financial corruption scandal of misusing Global fund in Ethiopia. #NoTedros4WHO\n— Amsalu (@AmsaluKassaw) April 28, 2017\nThey have organized Twitter campaigns under a hashtag #NoTedros4WHO to organize conversations surrounding the topic. To make his Ethiopian government profile at the top of the public’s consciousness, his opponents have share detailed research that accuses <PERSON> of inefficiencies, misreporting, and exaggerations of his achievements when he used to serve in Ethiopia.\nOne of the images that have circulated against <PERSON>, showing his face with an X over it next to the two other candidates. Shared by Twitter user <PERSON>, amid fears that the campaign might diminish his chances, government groups are also running a parallel campaign supporting his candidacy. They have downplayed the opposition as unpatriotic, mean-spirited and trivial jealousy.\nSince April 2014, a popular protest movement in Ethiopia has challenged the government, which has responded brutally.", "960" ], [ "According to Human Rights Watch, at least 800 people have died, and thousands of political opponents and hundreds of dissidents have been imprisoned and tortured. Since October 2016, authorities have imposed some of the world’s toughest censorship laws after it declared a state of emergency.\nThe role of ethnic politics\nSome of <PERSON>’ detractors say they oppose his candidacy because of his alleged incompetence. But a big part of what drives the fierce opposition to <PERSON> is the logic of ethnic politics.\n<PERSON> holds a Ph.D. from the University of Nottingham in community health. He studied biology at Asmera University before he completed a master’s degree in immunology of infectious diseases in London.\nWhen people hear his name, as qualified as he may be, his opponents associate him with a repressive Ethiopian government that has killed people, jailed thousands of political opponents, and imprisoned and tortured dissidents.\nHis meteoric rise to power started soon after he finished his Ph.D. in 1999 when he was tasked to lead the Tigray region’s health department. After two short years in Tigray, he was promoted to Ethiopia’s minister for health by the late prime minister <PERSON>, a Tigrayan himself. In 2012 when <PERSON> died, <PERSON> became Ethiopia’s foreign minister.\nTigray is one of the nine regional states that are federated based on ethnolinguistic compositions.\nOver the past 26 years, the Tigrayan elites have taken center stage in Ethiopia’s political affairs, largely due to their control of the military, security and the economy of Ethiopia. Though accounting for only 6% of Ethiopia’s population, all senior positions of country’s military and security and the most meaningful positions in state institutions are packed by Tigrayan elites. This has always been a sore point with the elites of the Oromo and Amhara ethnicities, who together comprise 65% of Ethiopia’s population.", "409" ], [ "Expelled Chinese diamond mining firm quietly returns to Zimbabwe · Global Voices\nA secret airstrip was built in a diamond field seized by the Zimbabwe army in 2007. Zimbabwe has long struggled with diamond mining exploitation from foreign companies. Photo by <PERSON> via Flickr CC BY-NC-ND 2.0.\nThe quiet return of expelled Chinese mining company Anjin Investments to diamond fields located in eastern Zimbabwe have sparked concerns of exploitation of Zimbabwe's resources under President <PERSON>'s administration, natural resource experts have said.\nThe state restored Anjin's license following intense pressure on Harare by Beijing, and the company has begun setting up operations earlier this month.\nReturn of Anjin To Marange Diamond Fields: the blindside of Zimbabwe is open for business agenda https://t.co/g0uv4yIuTI\n— <PERSON> (@mukasiri) February 10, 2019\nAnjin's history of exploitation\nAnjin Investments is a joint venture between the Anhui Foreign Economic Construction (Group) Co Ltd (Afec), and Matt Bronze Enterprises, formed by Zimbabwe’s defense ministry and the Zimbabwe Defence Forces.\nAnjin Investments and other diamond companies were stopped from mining the diamond fields located in Marange by former President <PERSON>’s government in 2016 following allegations of failing to remit taxes.\nMarange is a diamond-rich area located 400 kilometers east of the capital Harare within Manicaland Province.\nZimbabwe's office of the auditor general and parliament noted that Anjin Investments had never produced financial statements to account for its diamond mining operations.\nAccording to a parliamentary report on record , between 2010-2015, Anjin produced approximately 9 million carats which generated about $332 million United States Dollars in revenue.", "424" ], [ "Out of that figure, $62 million USD went to the government as royalties and $86 million USD was spent under corporate social responsibility.\nHowever, due to its military connections, Anjin Investments constructed a defense college at a cost of $98 million USD.\nThe company was one of the seven companies that were permitted to operate in Marange diamond fields prior to the consolidation of the mines in 2016.\nThe other companies included Mbada Diamonds, Diamond Mining Corporation, Jinan Investments, Marange Resources, Kusena and Gye Nyame. Government-owned a 100 percent stake in Marange resources and 50 percent in the other six diamond-mining entities in Marange.\nThese companies were forced into a merger to create the Zimbabwe Consolidated Diamond Company (ZCDC), but Anjin resisted the move.\nAnjin and Jinan were negatively affected by the merger, angering Chinese authorities who viewed the move as an assault on property rights and a violation of the investment agreement companies shared with the government.\nThis development also led to the overall deterioration of relations between former president <PERSON> and the Chinese, who had been his “all-weather friends.”\nIgnoring human rights abuses\nWhen Anjin left Marange, they dismissed hundreds of workers without paying their outstanding salaries and severance packages. The company was accused by its employees of racism and abuse of workers.\nAnjin recently recruited scores of employees at Chibuwe village, with the assistance of local councilors who were asked to provide names for the company to select, according to <PERSON> , director of the Centre for Natural Resource Governance:\nLack of transparency regarding the return of Anjin, therefore, raises these questions, who authorized them to mine in Marange? Why were formal government institutions overlooked?\n<PERSON> joins ZCDC, which has also been plundering Marange and committing horrific human rights abuses without any tangible benefits to the community.\nChibuwe village is located within Manicaland near Marange, situated at the deep end of the Save Valley.\n<PERSON>, provincial mining director for Manicaland, expressed ignorance about the presence of Anjin when contacted for comment.\n<PERSON>, permanent secretary in the Ministry of Mines and Mining Development, also professed ignorance on the matter saying as far as he was concerned Anjin does not have a permit to be in Marange. <PERSON> said:\nAnjin is one of the companies we are in discussions with but no decision had been made on their return.\nTHE RETURN OF ANJIN INVESTMENTS TO MARANGE – ZIMBABWE GOVERNMENT PROFESSES IGNORANCE https://t.co/clkfYlSTJZ @FMaguwu @mlevu28 @onhachi pic.twitter.com/1We3n7tGv9\n— CNRG Zim (@CNRG_ZIM) March 25, 2019\nWill history repeat itself?", "424" ], [ "Syrian refugees in Lebanon continue to play the resettlement waiting game · Global Voices\n<PERSON>, originally from Syria, sits inside his home in a makeshift Syrian Refugee Camp in the Bekaa Valley of Lebanon. Photo by <PERSON>. Used with permission.\n“The camp is better now than it was,” <PERSON> told Global Voices. As the informal leader of a small gathering of Syrian refugees at Al-Rihaniya Shelter Centre in Akkar in northern Lebanon, <PERSON> adds: “Although it’s still like a prison.”\nResettlement is the only hope for a better life for Lebanon's roughly one million Syrian refugees, but it often involves unpredictable waiting in dire circumstances.\nWhile some electricity exists, refugees must collect water across the road and use communal toilets. Roughly 1,000 inhabitants live in makeshift tents provided by the United Nations High Commissioner for Refugees (UNHCR), despite living at the site for several years. Residents can theoretically leave the centre but they must pass through security checks.\n<PERSON> recalls:\nOne resident went out and got stopped at a checkpoint near Tripoli [Lebanon] and put in jail for three days because he didn’t have the proper ID. On his way home after his release, he got stopped at the same checkpoint in the other direction and spent another three days in jail.\nSyrian refugees in Lebanon commonly experience this type of “Waiting for Godot” story. While most aspire to return to Syria, many have deserted from compulsory military service or have had previous run-ins with the current regime, which complicates the possibility of a return — even if the war ends.\nMost Syrian refugees in Lebanon do not possess a security identification card, restricting their freedom of mobility despite the supposed benefits of UNHCR’s official policy on providing alternatives to refugee camps. In reality, many refugees do not receive aid without an official address and must pay extortionate rent for substandard accommodation or small plots of land to place their tents. Locations, where refugee families congregate (from a few up to hundreds), are known simply as “gatherings.”\nA few years ago, families received rations of around 260,000 Lebanese British Pounds (about $175 United States Dollars-USD) per family, per month from the UNHCR.", "779" ], [ "But the UNHCR’s funding reduced so drastically that refugees no longer receive cash, only a food parcel. Payment for medical care or gasoline for heaters (a necessity in the winter) must come from their own pockets.\nChildren play in a makeshift Syrian Refugee Camp in the Bekaa Valley of Lebanon. Photo by <PERSON>. Used with permission.\nWaiting for resettlement, one delay at a time\n“We would go anywhere,” says <PERSON>, an Al-Rihaniya resident. Nearly 18 months ago, he and his family were invited to attend a resettlement interview by the UNHCR.\nAfter two long days of interviews in the UNHCR offices in Tripoli where every detail of their lives in Syria was laid bare, the family was elated when authorities informed them that their story checked out and met all the criteria for resettlement in France.\nCongratulations flowed from the UNHCR office staff as the family returned to al-Rihaniya to receive yet more congratulations and say goodbye to their neighbours and friends. A few days passed; then weeks; and then months, without hearing any word from the UNHCR about their resettlement.\nAfter five months of waiting, <PERSON> finally received a call: “Apologies for the delay, but France did not accept your file.” Nearly a year later, the family is still under consideration for resettlement in other countries.\n<PERSON> and his wife <PERSON> sit inside their tent in a makeshift Syrian Refugee Camp in the north of Lebanon. Photo by <PERSON>. Used with permission.\nThe resettlement process is often fraught with these kinds of vagaries.\n<PERSON>, originally from Hama, Syria, now lives in an informal gathering in the Bekaa Valley. On his wedding night in 2012, security forces of the government of <PERSON> came to arrest him on suspicion that he was involved in the rebellion.\nThe soldiers took pity on <PERSON> on his wedding night but warned that they would return the next day. After the nuptials, <PERSON> and his wife <PERSON> fled to Lebanon. Almost five years later, in March 2017, the pair took part in a series of interviews with the UNHCR and also received approval for resettlement.\nHowever, <PERSON> has a 17-year old son from a previous marriage who lives with <PERSON> and <PERSON>.", "779" ] ]

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[ [ "Howdy all. So I'm a pretty big Dominant Species fan and was very excited when I heard that DS would get all new artwork in the 3rd printing. My set came yesterday and I immediately took it out, compared against the 2nd ed, and played a game to see the new pieces in action. Here are my thoughts:\nI'm going to take a minute to acknowledge the whole artwork debate here for a second. Games are personal things, they are labors of love and BGG gives us the very unique chance to discuss them with the artist. Knowing that makes it very difficult for me to pass judgement on things like art quality because I know that I am basically telling someone \"You aren't good at a thing\" to their face. I have tried to stay out of the DS artwork debates here for that very reason. In this review I will do my best to focus on the FUNCTIONAL changes brought around by the new artwork and will keep value judgements firmly in the realm of \"My taste\". That is, I recognize what kind of artwork resonates for me doesn't resonate for everybody. This means that I am not going to say any artwork before or after was bad, just that I prefer one over the other.\nThere, got that out of the way. On to the bits. Please excuse my lousy off-kilter pictures.\nHexes\nFunctional improvements include far easier to read text and scoring values right on the hex itself. These are tremendously helpful. The change from 'Terrain Tile' to \"Wanderlust Tile' is subtle but positive in my opinion. Now the tile is directly tied to the action itself. More importantly, the back of the tile matches the gameboard and no actual terrain tiles. The old terrain tile looked a good deal like the desert and on a quick glance could easily be confused as still being available. With these new backs it is clear which tiles are available for selection. I'm a big fan of the new artwork on each piece; it is high resolution and vibrant.", "386" ], [ "The mountain and jungle hexes in particular are quite detailed. What's more, everything really pops on the new white board.\nCards\nthe dark backgrounds with the light text makes readability trivial. The different coloring for the Ice Age card sets it apart from all the rest. Beyond that the artwork is absolutely beautiful on the new cards. I enjoy that many of them took their inspiration from the original DS cards.\nelements\nThe changes to the elements are subtle but important. Each element has a slightly redesigned icon and a dark boarder. While the images are very much the same the coloring is far bolder than before. This helps with gameplay quite a bit as the elements stand out against the hexes better than before.\nPlayer's Aids\nNot a lot of differences here. You've lost the unique backgrounds from the original players aids (each species had a different background) and have replaced it with the same ice themed background on each. I do like how the color-coded speciation text stands out against the background a little better, but aside from that, few differences.\nThe Board\nGetting past the artwork itself the board is much improved from a functional perspective. Going to a ice themed background lightens the board considerably which makes text, particularly that in the bonus points table and the scoring track, far easier to read. Black on white text or white with a drop shadow really pops from across the table. Notice how much more the reset phase text or the action title text (Initiative/Adaptation/etc) stands out. I tend to think the eyeball logo looks a little out of place now but that's a personal taste issue.\nAll in all I am a huge fan of the update. I know it's a bit of a holy war here, but I think that a number of changes were made for playability as much as anything else. As far as my personal tastes are concerned, I love the new vibrant artwork. It is a far cry from the minimalist design, but it also isn't so busy that you lose your pieces on the tiles. Not even the green one on the savanna or the blue ones on the wetlands. It all just works and was clearly the effort of not just an artist, but a solid graphic designer. Completely worth the upgrade in my opinion.", "336" ], [ "Image Courtesy of bpovis\nThis review continues my series of detailed reviews that attempt to be part review, part resource for anyone not totally familiar with the game. For this reason I expect readers to skip to the sections that are of most interest.\nIf you liked the review please thumb the top of the article so others have a better chance of seeing it and I know you stopped by. If you thumb the bottom as well, I consider that a bonus. Thanks for reading.\nSummary\nGame Type – Card Game\nPlay Time: 30-45 minutes\nNumber of Players: 2\nMechanics – Card Drafting, Set Collection, Hand Management\nDifficulty – Pick-Up & Play (Can be learned in under 20 minutes)\nComponents – Very Good\nRelease – 2012\nDesigner –<PERSON> -( Agility)\nOverview and Theme\nIt is fair to say that there are some themes that are so pervasive within our hobby that some gamers may have 10 or 20+ games with the same theme on their shelves. I'm thinking fantasy, zombies, Egypt, Cthulhu, pirates...the list goes on.\nBut every now and again we are lucky enough to stumble across something rather unique. Morels is one such game. This is a game where two players are looking to walk through a forest, hoping to find many types of Mushrooms. Some they will cook and others they will sell in order to gain some valuable information from locals as to the whereabouts of other Mushrooms in this neck of the woods.\n<PERSON>, upon first glance and read, appears to fit into that gaming space occupied by , and . I am eager to see if this can be another hit in that 2-player card game space for games that are easy to learn but have a little depth to them.\nI'm also quite happy to be covering another game by a small independent publisher in . For the record the game was released in Europe under the title Fungi before this reprint. I will also look at what the Forays expansion adds to the game before I am done.\nPass me that stick there will you? My legs aren't what they used to be.\nThe Components\nFor a smaller publisher, Morels is a very well put together production, should be proud of the quality on offer. In one offering or another the company also provided gorgeous little pan miniatures and hand forged foraging sticks. These look great (check out the image gallery) but I only have the standard release.\nMushroom Cards – Naturally cards are going to be the front and center element of the game.", "470" ], [ "The cards on offer feature two different card backs to represent the Day and the Night Deck. The cards in the Day Deck are sometimes referred to as the Forest Deck as they will be drawn to make up the Forest Row or Ring (depending on how you set out the game).\nThe cards in the game largely feature a variety of different mushrooms. The cards allow artwork to take center stage. The key information beyond each card's name are the icons and values in the top left corner. The number below the symbol of a pan represents the card's value when cooked. The number below the icon of a stick represents the card's value in Foraging Sticks if sold to the locales. The artwork itself is good but not amazing.\nThe Night Cards feature the same mushroom types as the Day Deck except they come in a night-time hue and feature different artwork. The only mushroom missing in this deck is the Morels Card.\nImage Courtesy of Peterweb\nSpecial Cards – The other cards represent non-mushrooms and include things like Baskets, Pans, Moons, Butter and Cider, all of which I will cover later. In particular the Butter and Cider cards feature a simple criterion that must be met to play them, in the top-left corner.\nImage Courtesy of Alice87\nTokens – The game comes with a pair of Pan (as in fry pan) tokens, which are round and each player starts with one of these. Then there are a bunch of round Foraging Stick tokens, largely green in colour. These can be gained during the game to aid the players.\nImage Courtesy of Alice87\nRules and Reference Cards – The rules are decent without being brilliant - they get the job done. Oversized reference cards outline to the players how many of each card (mushrooms and specials) are in the main deck. This is important information to have.\nImage Courtesy of <PERSON>\nOverall I think the production of the game is up there with the quality of many of the games in the 2-Player line. Sure, there isn't a nice matte\\linen finish on the cards but from a smaller publisher I can overlook that.\nImage Courtesy of <PERSON>\nSet-Up\nIn keeping with the quick playtime, Morels is an easy one to set up.", "872" ], [ "This review continues my series of detailed reviews that attempt to be part review, part resource for anyone not totally familiar with the game. For this reason I expect readers to skip to the sections that are of most interest.\nImage Courtesy of <PERSON>\nSummary\nGame Type – Dice Game\nPlay Time: 20-40 Minutes\nNumber of Players: 2-5\nMechanics – Dice Rolling, Dice Management\nDifficulty – Pick-Up and Play (Can be learned in about 10 minutes)\nComponents – Good\nRelease - 2012\nDesigner – <PERSON> (All things Bohnanza, Agricola, At the Gates of Loyang, Babel, Le Havre, Ora et Labora)\nOverview\nWhen I started my journey into the new age of gaming around 2000-2001, Bohnanza was one of the first games I played and I loved it.\nThat still rings true today despite the fact that I play it far less than I used to. So when I heard that the <PERSON> family finally had its inevitable dice game conversion, I knew I had to try it. I prepared myself however for the worst and despite my love of dice games in general, I am getting pretty tired of the current trend to turn almost any successful game or franchise into a cheap and easy dice spin-off version.\nDespite being a dice game, the theme found here holds largely true to the original card game. Players are trying to roll dice in order to plant beans (lock them in), which can then be harvested once a harvest order is completed in full. The more harvest orders that are completed, the greater the payoff when a player decides to cash-in.\nSo how do the old beans fair when they are on dice? Is this a cynical money making exercise or a gaming experience worth your hard earned? Let's find out.\nThe Components\nLike any good filler dice game the components required are fairly minimal...\nDice – The stars of the show are the 7 dice that feature a total of 7 different bean types. Most are common to the card game.\nWhat requires mention is that the dice are split into 2 distinct dice types or sets, a group of 4 like dice and a group of 3 like dice. Both sets differ in the types of beans they offer and how many of each.\nStraight away it becomes evident that the game may require some dice management to maximise your results and this is certainly true.\nThe group of 4 like dice feature a white background, whilst the set of 3 like dice feature a beige background. At best this colouring is not highly evident and at worst it is very hard to see under poor lighting, which is a shame but not a game breaker.\nMost of the time it is not an issue but something could have been done to rectify it in production.\nThe faces themselves are painted on rather than etched but mine are yet to show any serious wear.\nPlease note that in the image below the orange looking dice has been coloured by the owner to help better identify the beige from the white dice. I have not felt the need to do this.\nImage Courtesy of Liumas\nHarvest Cards – The other major component is the Harvest Cards, which the players are trying to fulfill with their rolls.", "581" ], [ "Each card features a total of 6 different orders and the criteria for each order is listed using icons that are easy to understand.\nThe other feature worth noting is that coins/gold or (in Bohnanza speak) Beantalers are listed on the top half of the card. These BEantalers (1-4) are the rewards on offer for completing 3 or more orders.\nThe backs of the cards feature the same classic image of the golden Beantaler, that every Bohnanza game tends to use. These are used to keep track of a player's score as they complete orders and collect their gold.\nThe cards are a nice bit of design. It isn't necessarily impressive but it does the job, is easily understand and allows the game to flow quickly and easily. The cards also feature a matte or linen finish, which is in keeping with the European quality standards that companies like Amigo tend to uphold. Bravo!\nOne element I do like about the Harvest Cards though is that there is much variety in the orders that you need to complete. In all there are a total of 64 cards and 9 different types of orders (with many variations within those types) that need completing. This variety helps the game to feel varied.\nImage Courtesy of Artax\nBean Field Template - A box-sized Bean Field Template is also provided. This is an important feature as it serves as a location for the players to move their 'locked-in' beans to and helps avoid having rolled dice hitting 'locked-in' dice. It also helps to easily identify which dice are still active and which are not.", "872" ], [ "Image Courtesy of kherubimThis review continues my series of detailed reviews that attempt to be part review, part resource for anyone not totally familiar with the game. For this reason I expect readers to skip to the sections that are of most interest.\nIf you liked the review please thumb the top of the article so others have a better chance of seeing it and I know you stopped by. If you appreciate the time taken to write and the depth of analysis, please consider thumbing the bottom as it tells me I've helped you in some way. Thanks for reading.\nSummary\nGame Type - Card Game\nPlay Time: 10-15 Minutes\nNumber of Players: 2-4\nMechanics - Set Collection, Card Drafting, Auctions/Bidding, Hand Management\nDifficulty - Pick-up & Play (Can be learned in under 10 minutes)\nComponents - Excellent\nRelease - 2011 (Originally released as Scripts and Scribes in 2007)\nDesigner - <PERSON> -( Biblios Dice, Capo Dei Capo, Cosmic Run, Gunrunners, Let Them Eat Shrimp!, Slush Fund)\nOverview\nWelcome brother to the conclave of the monks. As you can see we are all friends here but we take the ancient competition very seriously. As one of the esteemed order of Abbots, you are now engaged in the task of collating the greatest collection of holy books known to man. Acquire them any way you can with the limited funds at your disposal and if successful, your influence will spread throughout the land as the one to have created the greatest library of all.\nThis is Biblios, a card game with a religious background but in truth the game is really about set collection. I have my faith but do not practice my religion in any great way...and I love this game. So the theme doesn't have to be a barrier if you don't let it. Of course for others it may appeal greatly.\nI first played this game back in 2010 as Scripts and Scribes at a gaming convention. I remember thinking the game was pretty good but it was hard to come by and so I moved on. In the years that followed picked it up and created Biblios. I acquired a copy as a purchase in a Math Trade for cash but when it was delivered to me at the same Con years later, I had no choice but to sell it at the end of the weekend for double what I paid ($60!).", "470" ], [ "And so it eluded me again.\nFast forward a year or two and finally the game was more readily available and I now I have a copy of my very own. My mission? To revisit this light card game and declare once and for all if it is worthy of my worship! Oh man...that's worshipping a false god...I'm going straight down when I die.\nThe Components\nBiblios comes in a great package. Not only is the box as small as it needs to be but it is designed to look like a book with pages on one end and a spine on the other. It really supports the theme of the game and to top it off the box closes with a magnetic flap, so everything stays exactly where it is supposed to, even when standing up on a shelf. Bravo . How I wish all card games of this box size did this.\nThe stuff inside the box is pretty good too...\nBoard – Despite being a card game, Biblios does feature a small board, to accommodate the dice. This component is largely the reason for the box size as it is. The board isn't super fancy in any way but the graphics are engaging and it is clear as to its purpose. The thickness is really good and the dice allocation positions are even separating slightly into two groups to help remind the players that the 5 sets of cards in the game have slightly differing values.\nI find this extremely helpful and it is a great example of thoughtful design.\nImage Courtesy of EndersGame\nDice - When you first look at the dice you can't help but think, \"Man they are chunky. Not sure if they will roll well.\"\nThen you read the rules and realise they are not to be rolled at all. The purpose of the dice is to serve as a visual representation as to the values for each category of cards, throughout the play.\nThe dice come in 5 colours that match the colours of the card sets in the game. They do the job well enough.\nImage Courtesy of zombiegod\nCards - But of course it is the cards that are the central component of the game. There are 87 cards in total and in all there are 3 different types - Money Cards, Church Cards and Category Cards.", "872" ], [ "Image Courtesy of <PERSON>\nThis review continues my series of detailed reviews that attempt to be part review, part resource for anyone not totally familiar with the game. For this reason I expect readers to skip to the sections that are of most interest.\nIf you liked the review please thumb the top of the article so others have a better chance of seeing it and I know you stopped by. Thanks for reading.\nSummary\nGame Type - Card Game\nPlay Time: 50-70 minutes\nNumber of Players: 2\nMechanics - Modular Board, Worker Placement, Set Collection\nDifficulty - Pick-up & Play (Can be learned in 20 minutes)\nComponents - Very Good to Excellent\nRelease - 2012Artist - <PERSON>\nDesigner - <PERSON> Title)\nOverview and Theme\nTargi takes us to the ethnic peoples of Northern Africa that call the Sahara Desert home. Your people live in nomadic tribes and it is the men (Targis) that cover their faces whilst the women (Targia) do not. As leader of one of these nomadic tribes you must trade the goods of the land in order to acquire gold and better your position. Your aim is simple enough, to support the largest tribe.\nTargi is the debut title of <PERSON> I won't hold any punches up front here when I say that he has produced an excellent 2-player game and one that is totally deserving of finding a place in the revered 2-Player series of games.\nHop on that camel and come with me...I have a most enjoyable journey to take you on.\nThe Components\nalways put together a good production and this is no exception. Not surprisingly, cards dominate the components.\nBorder Cards - Instead of utilising a board, Targi provides 16 cards that act as Border Lands or regions to frame the central play area. Rather than simply creating a border, these cards are actually part of the play area as well. As such they are double-sided with text on one face to outline the ability and iconography on the other (which does the same thing in a more simplified way).\nLike all of the cards in the game, the thickness is serviceable but they only have a glossy finish.", "470" ], [ "All cards in the game use a landscape orientation.\nThese border cards also feature a little bit of artwork to differentiate each quarter of the border with a different terrain. It is totally unneccessary but a nice touch all the same.\nImage Courtesy of Alice87\nTribe Cards - The game comes with 45 of these cards of which their are 9 of each type. These cards represent ways in which a tribe can gain assets and wealth and include things such as camel riders, oases, wells, camps and Targia's (women - and for the record this is not as assets like in a harem because Targia's lead these tribes).\nThe cards are elegantly organised with a graphic to denote the type on the left, the cost of each card in the top right and the VPs it is worth in the bottom right. If a card has a text-based ability it is located centrally.\nIt's all very crisp.\nImage Courtesy of henk.rolleman\nGoods Cards - These are much simpler affairs as they simply feature central graphics to show what goods are earned by taking a given card. Three cards also feature a gold coin and another a VP icon.\nLike the Tribe Cards, these utilise a sand dune background that evokes the theme and offers a neutral colour palette to help the foreground colours stand out. I also appreciate the shadow effect of the artwork, as if a burning sun is beating down on the cards.\nIt's nice stuff.\nImage Courtesy of <PERSON>\nMeeple - These are nice wooden affairs that come in two players and a grey meeple serves as the Robber.\nSquat cylinders serve as the Tribe Markers.\nImage Courtesy of <PERSON>\nTokens - The Goods tokens are simple square counters and feature the same graphics that are used on the Goods Cards. The VP tokens are quite an irregular shape to help them stand out and no doubt they are based on some form of trinket used by North African tribes.\nImage Courtesy of henk.rolleman\nFirst Player Amulet - A medium sized token is used to represent this marker to denote who goes first in a turn. It's quite noce to look at.\nImage Courtesy of <PERSON>\nRules - The rules are very well done. I found no ambiguity whatsoever in my edition ( ) and they feature good examples to boot.\nImage Courtesy of <PERSON> the game offers great value for money and looks great into the bargain. The artwork is simple but Vohwinkel(as he always does) manages to evoke the setting and theme of the game in a way that is refreshing.", "84" ], [ "Image Courtesy of otrex\nThis review continues my series of detailed reviews that attempt to be part review, part resource for anyone not totally familiar with the game. For this reason I expect readers to skip to the sections that are of most interest.\nIf you liked the review please thumb the top of the article so others have a better chance of seeing it and I know you stopped by. Thanks for reading.\nSummary\nGame Type – Deck-Building Game\nPlay Time: 60-90 minutes\nNumber of Players: 2-5 (Best 3)\nMechanics – Card Drafting, Deck Building, Hand Management, Action Point System\nDifficulty – Pick-up & Play (Can be learned in 30 minutes)\nComponents – Good\nRelease – 2011\nDesigner – <PERSON> -(Assault of the Giants, Canterbury, Dungeon Alliance, Dungeons & Dragons: Attack Wing, Ideology: The War of Ideas, Justice League Strategy Game, Parthenon: Rise of the Aegean, Star Trek: Attack Wing, Star Trek: Frontiers)\nOverview and Theme\nEvery now and again a game can escape my clutches but I eventually get back to them. Core Worlds is one such game. I picked this up in the year of its release, some 6-7 years ago and after one play that took almost 3 hours I was done with it. The game seemed too fiddly, the rules I found tricky to navigate and it just went to long for what it was. The easier to grasp Ascensionhad been released the year before and that was enough for me.\nTake a cosmic space jump to 2017 and I am back to try this baby again. I understand deck-builders a lot better now than I did then and...well...let's see what we have here...\nThe galaxy is at unease. The Core Worlds have ruled with an iron fist over all systems and planets within its reach. The outer rim planets were the worst treated to be sure, considered nothing more than resource pits to sustain the life of the inner realm. The rim's people were nothing more than a resource to be used up and discarded.\nBut something has changed, there is a faltering within the Core Worlds and the rim has felt the loosening of the reins for some time. Now is the time to strike. They call us barbarians but we are a hardy people and we have learned to adapt.", "299" ], [ "Now it is our turn to take the fight to the Core Worlds and take control of what is rightfully ours!\nSuch is the theme of Core Worlds. The players are in control of an outer rim faction and a single planet. The aim is to travel to the Core Worlds, building your fleets and ground forces for the final assault and claiming any planets along the way that are ripe for invasion. A Deck Builder fits the theme nicely as the mechanics are largely supporting the theme of the story.\n<PERSON> probably best known amongst Euro fans for Canterburyand perhaps more widely known for his work on the D&Dand Star Trek Attack Winggames. Beyond that though his designing career is quite varied\nLet's see what he has for us here.\nClose the gang ramp will you and strap yourself in, we blast off in 5 minutes.\nThe Components\nBeing a deck-building game, cards are pretty much what dominate the components. So I'll take a look at the different kinds of cards and then a few of the extra bits.\nPlayer Mats – Ok I lied. Core Worlds makes use of player mats or boards that are pretty important to the play. They allow the players to track how many actions they have at any given time and the amount of Energy they have in their Empire.\nThe top of the mats also outlines each of the Core Worlds and their associated scoring benefits. This is not critical to know but it is useful as it allows players to plan ahead for when they reach Sector 5 (the end-game).\nDown the left side are listed the possible actions that can be taken in the main phase of the game.\nThe only downer here is that the mats are a little thinner than they could have been and are prone to a little bit of warping over time.\nImage Courtesy of vantageGT\nWorlds – These cards are always green in colour and feature a planet of one type or another as the central artwork. Four key numbers feature in each of the corners and sometimes a World may have a power that is featured in text below the artwork. In the top left is a number in a yellow circle...this denotes how much Energy the World can produce when conquered and added to a player's Empire. In the top right is a number in a red circle. This reflects how many Empire Points (victory points) the World is worth.\nThe two numbers at the bottom reflect the defensive Fleet and defensive Ground Force strength of the planet. These numbers must be equalled or bettered in order to conquer the planet.", "299" ], [ "Image Courtesy of <PERSON>\nThis review continues my series of detailed reviews that attempt to be part review, part resource for anyone not totally familiar with the game. For this reason I expect readers to skip to the sections that are of most interest.\nPlease thumb this review if you appreciate my work. It does put a smile on my face to know you stopped by. Thanks for reading.\nSummary\nGame Type – Dice Game (Expansion for base game)\nPlay Time: 50-120 minutes\nNumber of Players: 1-5\nMechanics – Dice Rolling, Dice Allocation\\Manipulation, Drafting, Set Collection, Variable Player Powers\nDifficulty – Moderate (Requires a few plays to see how the various elements fit together in order to do well)\nComponents – Excellent++\nArtist – <PERSON>, <PERSON>, <PERSON>\nRelease – 2018\nDesigner – <PERSON> -( Bullfrogs, Floriferous, Herbaceous, Maul Peak,All things Roll Player, Roll Player: Adventures, Skulk Hollow, Sunset Over Water, The Whatnot Cabinet)\nOverview and Theme\nWelcome back to the lands of Roll Player, fellow adventurer. Once it was enough to simply 'be', decked out in your finery, weapons gleaming, skills at the ready and traits to define you. Your attributes were key to your success as a hero of the realm, but things have changed.\nNow, it is time for action! An evil Monster is menacing the lands of the king and they have sent foul Minions to do their bidding. It is time...time to put that gleaming sword and wicked sling to use! The king has ordered you to make plans, it is time to prepare yourself once again and this time you will need to discover the secrets of your quarry if you are to stand any chance of slaying it.\nThat is the backdrop to the first expansion for Roll Player. It adds to the scope of the game by adding the additional action of 'Going on a Hunt', which allows a player to forgo the regular Marketplace Actions to instead fight a Minion and in doing so, learn about their master, the Monster who is the centre point of the game's climax.\nI will not be covering all of the rules to Roll Player here, instead I would direct you to my review of the base game(Roll Player - A Detailed Review).\nHere I will be covering new actions and most importantly, how the game is changed and the new considerations brought about by the content of this expansion. I will also discuss the solo game and any differences there as well.\nGrab me that longsword <PERSON>...and yes you better sharpen it this time. The bloody king actually wants me to fight a Monster.", "470" ], [ "But... (whimper) I've just had my hair done!!!\nThe Components\nand its primary adventurer in <PERSON> a great job of producing a high quality game. All of the cards feature a matte\\linen finish and it all feels like care was taken. Sure the game costs more than some games via Kickstarter (which is how I got my copy), but I am prepared to reward a company that goes the extra mile. I have no connections to the company in any way.\nNew Character Sheets – In all the expansion offers up 5 new Character Types in the form of the Bastja (cat-people), Construct (mechanical being...think <PERSON>'s sister [Nebula] in Guardians of the Galaxy), <PERSON>, Gnome and Wrathborn (devil kin).\nThe boards are nice and thick as per the original game and have lovely cutaways to place dice. Space is also afforded to allow elements such as Class, Backstory and Alignment Cards to be placed and managed.\nThe boards are great, being just big enough to be supportive of the playing experience without taking up more table space than necessary.\nImage Courtesy of Alice87\nMonster & Adventure Cards – In all 6 Monsters at the more gargantuan end of the scale are provided to enhance the fantasy theme. They include the Giant Troll, Vampire, Demon, Dragon, Kraken and Chimera. Each of these Monsters are linked to one of the class types based on colour (a diamond icon features in the top-right corner to signify this). In the top left-hand corner can be found a heart with a value. Normally this would signify a creature's hit points, the number of wounds needed to kill it. Instead it simply represents the Monster's Strength and the lowest possible combat total that must be rolled in order to score any Reputation Stars.\nLovely large-scale artwork fills two-thirds of the tarot-sized cards and beneath that the name of the Monster and their specific power is listed.\nBelow that are the iconic Reputation Stars and for each star a value-range is listed, which signifies what combat total must be rolled to achieve the associated reward.", "872" ], [ "Image Courtesy of Floodgate\nThis review continues my series of detailed reviews that attempt to be part review, part resource for anyone not totally familiar with the game. For this reason I expect readers to skip to the sections that are of most interest.\nIf you liked the review please thumb the top of the article so others have a better chance of seeing it and I know you stopped by. Thanks for reading.\nSummary\nGame Type – Euro (Dice Drafting and Allocation) Game\nPlay Time: 20-45 minutes\nNumber of Players: 1-4\nMechanics – Dice Drafting, Dice Rolling, Set Collection, Pattern Building\nDifficulty – Pick-up & Play (Can be learned in 10 minutes)\nComponents – Excellent\nRelease – 2017\nDesigner – <PERSON> -( Before the Earth Explodes, City of Gears, Roar: King of the Pride, Speakeasy Blues)\n+\n<PERSON> -( Before the Earth Explodes, Mine All Mines)\nOverview and Theme\nWelcome artists of the world! You are tasked with creating the most beautiful stained-glass windows, befitting of the amazing Sagrada Familia Cathedral in Barcelona.\nYour commission is a simple one...to create the most stunning window possible and in doing so beat your rival artists to the grand prize, the fame of your creation and knowing that you have added to this amazing building as created by the architect <PERSON>.\nOk so there you have the thematic backdrop. But what is Sagrada in a gaming sense? Quite simply it is a dice drafting and placement game that looks gorgeous as it goes about its evolution from set-up to completion.\nBefore we really tuck into this one, it is worth noting that Sagrada is another great game to come out of theGroup. I like to give a shout out to groups like this who are a part of creating great new games. One game that inspired or influenced the creation of Sagrada was , another great game to come out of this group.\nThis review is also timely as the relatively small publisher in are about to release the 5-6 Player Expansion for Sagrada. This expansion will be a bit more than just a player-increase title, offering up personal dice pools and new Private Objective Cards amongst a few other bits. It doesn't look to be a massive expansion in relation to content and many fans of the game will probably be thankful for that as bloat will not be an issue.\nGrab the Lens Cutter, oh and that Flux Brush please, we have a date some 30 meters up my good friend...it's time to create a masterpiece!\nThe Components\nOne of the major selling points of Sagrada is its vibrant appearance and great production values. For a small-publisher to provide a game of this quality and include 90 translucent dice at a decent price point...bravo!\nPlayer Boards – Each player board is shaped in that classic stained-glass window visage and features two distinct halves.", "470" ], [ "The top half is taken up by artwork, showing a stained-glass window with a dice of a given colour in its center. This colour is the dominant colour in that board's artwork but doesn't really denote that player as colour 'x' as the players are not represented by a given colour in the game (Scoring Tokens aside).\nThe bottom half is where the action is at though as this is where the game will be played and each player will create their own window. The bottom of each board features a latticework, which creates a 5 x 4 grid of spaces. At the bottom edge of each board a thumb space can be found at the back and a slot is present, which allows a Window Card to be inserted into the latticework. It's actually quite the intricate design compared to some games when you stop and think about it.\nWhat is also worth noting is the thickness of these boards. They are really great featuring two really thick boards glues together to produce a 5-6mm creation. The backs of the boards also feature lovely artwork, not that it is seen all that often.\nImage Courtesy of pandawear\nDice – The dice are the star of the show however and come in the small dice format, but most importantly, are translucent. Not only does this material choice best reflect the nature of a stained glass window, when the light catches them the game looks simply stunning.\nIn all there are 18 of each colour and of course the latticework on the Player Boards are sized to perfectly hold a single dice in each space.\nImage Courtesy of <PERSON> Pattern Cards – The game includes 12 double-sided Window Pattern Cards, allowing for 24 different designs to be offered. These are made from thin card to allow them to be inserted into the bottom of the Player Boards and in doing so the features on each card align with the open spaces of the latticework. Very clever stuff.", "872" ] ]

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[ [ "Hanging Leather Planter\nIntroduction: Hanging Leather Planter\nIn the spring, all nature comes to life. And despite the remaining snowdrifts outside the window, it's time to put the houseplants in order.\nMy wife recently transplanted an overgrown shoot of her favorite orchid into a new larger pot. The problem is that our flower rack holds a limited number of flowers, strictly according to the number of areas it has. And there were a little more flowers.\nBut I figured out how to save the situation and made a hanging leather orchid planter. Moreover, the location of the various areas just makes it easy to link.\nThe manufacturing process is quite simple and very exciting, as you assemble the constructor :) Try it!\nStep 1: Materials & Tools\nFor and manufacturing we need:\n1. A flower pot with a saucer - will not be damaged during the work :)\n2. Metal ring with an inner diameter of about 40mm\n3. Metal ring with an inner diameter of about 15mm\n4. Metal triangle with side about 15mm\n5. Ruler\n6. Awl\n7. Grinding knife\n8. Just a sharp knife (or rotary)\n9. Round punches 2mm and 8mm diameter\n10. Beveller 1mm\n11. Rivets - I have a 7mm head\n12.", "389" ], [ "Leather. I took vegetable tanned 2mm thickness\n13. Protective agent for skin and brush for application. I took Elixir from Kenda. It practically does not change the color and texture of the skin and quite well helps from water\n14. 6mm diameter rope (optional)\nStep 2: Marking Up the Straps\nWe need to mark three strips 25mm wide.\nThe length of the strips depends on the selected pot. I have a pot about 110mm high and 150mm in diameter at its widest point.\nWith such dimensions, the length of each strip should be 500-550mm. We'll cut off the excess later :)\nStep 3: Cut Strips\nWe cut the strips carefully and without haste.\nThe sharper the knife, the neater strips will come out. Rotary knives are generally very good for straight cutting.\nStep 4: Marking the Ring\nUsing a flower pot as a reference, mark how long we need a strip.\nThe strip should wrap around the top (wider) part of the pot. It is also worth considering that the strip itself should overlap by about 15-20mm.\nStep 5: Thining\nCarefully cut the strip according to the mark made in the previous step.\nSo that the overlap is not conspicuous, you need to thin the ends of the strip.\nThin the left and right edges by approximately the width of the overlap. For the process to go neatly and easily, the knife must be very sharp.\nImportant: on the one hand, we thin the front side of the skin, and on the other - the back side!\nStep 6: Hole Marking\nWe mark the places for the holes.\nFirst, mark the holes along the edges. When you connect them, we get a ring.\nThen we divide the distance between them into 4 equal segments.\nStep 7: Punching Holes\nWe punch all the holes marked in the last step. Diameter 2mm.\nStep 8: Divide in Half\nWe carefully divide the remaining two stripes in half.\nThus, we have 4 strips of about 250 mm in length.\nStep 9: Rounding the Corners\nRound off the corners on one side of each strip. This side will be attached to the metal ring.\nStep 10: Thining\nThin the reverse side of the skin where the rounding was made, 15-20 mm is enough.\nThis is necessary so that there is no large protrusion at the bottom.\nStep 11: Bottom Holes\nMark the holes at a distance of 10 mm and 50 mm from the rounded edge. This distance is quite enough when using materials similar to mine.\nAlternative: Try one strip on a large metal ring, mark in place. Transfer the markings to the remaining strips.\nPunch holes 2 mm in diameter.\nStep 12: Temporary Assembly\nWe assembly the cross from a metal ring and leather strips.\nWe connect everything with rivets or screws, but do not fasten it tightly, since this is a test assembly, it is only needed for fitting.\nStep 13: Marking the Cross\nUsing the pot as a reference, mark on one strip the place where the leather ring will pass and where to make holes for the suspension.\nWe disassemble the crosspiece into separate elements.\nStep 14: Marking the Cross Strips\nWe transfer the markup from the previous step to all other strips.", "421" ], [ "Silent Dice Tray\nIntroduction: Silent Dice Tray\nMy wife and I are big fans of board games with more than 10 years of experience :)\nSeveral years ago, the first baby appeared in our family. A couple of months after his birth, we started meeting friends to play board games. And there was always a very acute issue of noise when throwing dice.Most often we tried to throw them on the playing field (as a rule, cardboard, but in different games in different ways), it partially dampens sounds, but this is not very convenient: sometimes the dices dropp figures or move some tokens, and sometimes the cubes ran off to the table or even fell to the floor. And so you sit and listen with bated breath to the sounds behind the closed door, because there is a child sleeping in the next room ...\nAnd now a couple of months ago we had another baby :)\nThis time, we decided to thoroughly prepare for the gaming tabletop season. So that the dices no longer rattle, do not run away anywhere, so that you do not have to worry about every unsuccessful loud throw in a small apartment, we came up with a way out!\nIt was decided to make small beautiful trays specially for throwing dicess into them. A soft, stable base will dampen unnecessary sounds, the sides will help the cubes not to run away to the floor or far to the table. In general, adult life requires new solutions, and I believe that we have coped successfully :)\nYou can choose any shape, we took a couple of different ones for an example to show how it will look in different versions. Leather as a material is also not important, if you liked the idea, but you have never worked with leather, you can use felt or some kind of very dense fabric.\nYou can simply take this idea as a basis and successfully transform it for yourself and your reality, as it is more convenient for you :)\nGood luck with your dice experiments and success!\nStep 1: Tools & Materials\nFirst, it is worth deciding which of the proposed options you will do :)\nWe will need:\n1. printed pattern\n2. duct tape\n3. sharp knife\n4. awl\n5. punch round 2mm\n6.", "622" ], [ "creaser\n7. glue for leather\n8. thin foam approximately 1.5mm thick. You can take EVA foam.\n9. rivets with a head 4-5mm\n10. finish for leather edges (Tokonole or edge paint). I used Kenda Edge Paint\n11. thin lining leather\n12. leather 1.5-2mm thick\n13. threads\n14. sewing machine, although you can sew by hand, but this will turn out to be a very long seam.\nAn important clarification: if you decide to sew on a typewriter, do not use waxed thread.\nStep 2: Making a Pattern\nPrint, glue and carefully cut the desired pattern. The pattern has stripes for easy alignment of parts.\nIn this case, A4 sheets are used. If you have an A3 printer, then you don't have to glue anything.\nStep 3: Transferring the Pattern to Leather\nWhen transferring a pattern to the skin, it is very important to transfer the following parts:\n* outer loop\n* centers of all rivet holes\n* corners of the central gray area\nThe corners of the gray area need to be pierced through! You can even mark them additionally on the inside of the leather for convenience in the next steps.\nStep 4: We Leave Only the Blank\nTrim off any excess skin, but leave a margin on each side.\nYou don't need to be too greedy, my experience suggests that you should leave at least 10mm on each side. This will make life much easier during the bonding phase.\nStep 5: We Repeat\nIf you are making a bat, then repeat the previous two steps for the second pattern.\nStep 6: Soft Base\nMark only the gray inner areas of the patterns on thin foam.\nThese will be the inner bottoms, which will dampen the clatter of the cubes, and also add stability to our dices trays.\nStep 7: Cut Out\nWith a sharp knife or scissors, cut out these soft, quiet bases.\nStep 8: Marking the Indent\nWith the help of the creaser (I have 2mm) mark the indent on each side of the base.\nStep 9: Reducing the Soft Base\nWe cut off the soft bases along the lines marked in the previous step.\nThis will help to avoid problems when sewing the bottom and will allow the walls to bend more easily and evenly.\nStep 10: Glue the Indoor Soft Base\nIf you've marked the corners of the gray area on the inside of your skin, it will be much easier for you!", "421" ], [ "Bellows for Igniting Fire\nIntroduction: Bellows for Igniting Fire\nSpring has come and the whole summer is ahead - which means a lot of country trips, meeting with friends, relaxing in the wild or camping. And, of course, this is an indescribable aromatic cuisine on the grill or on the fire. And nowhere in all this diversity can you get away from the fire!\nIn the wild, this is an opportunity to cook food and warm up, in a camping it is a cozy atmosphere and songs with a guitar around the fire (in Russia, an integral point for summer evenings). And you can't live without food at all: coals for grilling, tandoor ovens, Finnish candles for cooking food in a frying pan - all this requires fire!\nTherefore, I would like to tell you about a device that greatly facilitates the campfire life. We are talking about bellows for kindling a fire.\nThe bellows are used to obtain a continuous air stream and are used mainly in blacksmithing and glass-blowing, as well as in some musical instruments (bagpipes, accordion). They have been known since ancient times, they were used in ancient Egypt.\nThe technical meaning of the device is that air is drawn into the inner space, and then leaves it in a continuous flow, which allows you to kindle a fire easily and without any difficulties. Regardless of the weather. Even in conditions of insufficiently dried firewood or coal. Easily and naturally make any fire in no time!\nLet's get started :)\nSupplies\n1. Plywood 9mm\n2. soft leather 1.5-2mm thickness\n3. Sander\n4. grinding machine\n5. boron machine\n6. furniture stapler\n7. screwdriver and drills\n8. wood glue\n9. stain\n10. varnish for wood\n11. a pen\n12. scissors\n13.", "548" ], [ "grinding knife\n14. glue for leather\n15. creaser\n16. hammer and nails with a large head\n17. double-sided thin tape\n18. copper tube\n19. Super glue\n20. ruler and compasses\n21. pattern building paper\nStep 1: Plywood Blank\nUsing a milling machine, we cut out all wooden parts from 9 mm plywood. You can use a material with a thickness of 10-12 mm, that will be great too. The structure will gain additional strength, but it is worth considering that the weight will increase slightly.\nI do not recommend taking thinner plywood, in order to avoid additional difficulties in the assembly process. In addition, there is a great risk that thinner plywood will break during use, we tried 6 mm - it broke :(\nStep 2: Grinding\nIt is very important to grind everything well. The better the material is processed, the more pleasant it is to work with it, and the smoother the paint and varnish fall on it.\nFor this I use a grinder and discs with a grid of 180, 320, 500 or 600 (here I do not pretend to be an expert, if you think that you need to grind with other discs, so feel free to do it, the main thing is a smooth result!)\nIt is not necessary to sand the edge strongly, since almost all edges will be covered with leather.\nStep 3: Handle Preparation\nWe make approximately the same bevel on the handle pads.\nThis bevel is not difficult to do, but it is very important for the aesthetic appearance.\nI do this at an angle on a sander using 80 grit discs and belts. After shaping, I create smoothness using the higher number discs from the previous point.\nStep 4: Marking the Place Under the Nozzle\nWe mark the trapezoid of a larger size. as shown in the photos.\nStep 5: Drill Approximate Nozzle Hole\nIn this step, we drill a hole with a drill bit much smaller than the nozzle, about 3-4 mm.\nThere are several reasons for this:\n1. it is more convenient to drill with a thin drill, less chance of drilling through in the wrong place\n2. can be drilled from both sides\n3. the walls remain quite thick, the part does not become brittle\n4. drilling a thin hole is easier than drilling a large diameter hole at once\nStep 6: Gluing Wooden Bases\nRead the instructions for your glue carefully! The quality of the connection of parts depends on this.\nWe only glue the handle strip to the short base.\nTo the base with a hole, on one side, glue the overlay on the handle, on the other side, first a large trapezoid, then a small one. Thus, a place is formed for the nozzle and fastening the bases to each other. We use clamps for high-quality gluing.", "56" ], [ "Cover for Skewers\nIntroduction: Cover for Skewers\nAt first glance, looking at the picture, it is not even very clear what it is. It looks like some kind of weapon :) Especially in this \"army\" color.\nI'll tell you why it was all invented. Quite often, my friends and I go to camping, fry meat, and now we have also got used to making chic cheese kebabs, for which skewers are simply irreplaceable. So after cooking, there is often no time, energy and desire to thoroughly wash them. It is much easier to do this at home (most of the time our sorties are short enough). And it is inconvenient to take dirty skewers home, they tear the bags in which they can be wrapped, the trunk in the car becomes dirty. If the skewers have their own good cover, then you cannot put dirty skewers there, because this is where all its beauty ends. I thought for a long time how to avoid all this.\nAnd so this case appeared! What's the bonus? Even unwashed, dirty skewers can be perfectly folded there, because the cover itself is easily disassembled and perfectly cleaned from the inside. Very comfortably!\nIn addition, it is convenient when you buy inexpensive skewers per piece, as a rule, in this case, they are sold without a cover, and they are compactly packed and perfectly stored, they are convenient to store, transport, they do not get dirty in the process, and always remain clean.\nIn general, I tried this thing and was very pleased with the option I made.\nAnd most importantly, it is quite easy to do! The first such cover in our family was made by my wife, we didn't even paint it :) This is a good option if you are looking for a very easy way. For beauty, you can also paint.\nIn general, try :)\nSupplies\n* Sewer pipe 50mm length 1m\n* Two sewer plugs 50mm\n* Sewer coupling 50mm\n* Sewer plastic adapter 73x50mm\n* Sewer rubber adapter 73x50mm\n* Hacksaw\n* Ruler and pen\n* Paint and primer\n* Sandpaper (I took 180 grid)\nStep 1: Determining the Size\nYou should already have skewers in order to make a cover for them.", "726" ], [ "I measured mine and marked the pipe 2 centimeters longer than the skewers\nStep 2: Cut Off Excess\nThis process does not require special care, the main thing is to try not to cut yourself :)\nStep 3: Cut Edge Processing\nUsing sandpaper, we clean the cut from burrs. We also remove the chamfer so that it can be easier to assemble in the future.\nStep 4: Preparing the Cover\nIt is enough to insert the plug into the rubber adapter and the cover is ready\nStep 5: We Throw Out the Excess\nUsually the plastic adapter already has a rubber seal. We do not need it, since the plug does not hold in it.\nStep 6: Assemble the Bottom of the Cover\nAnd again, everything is simple: insert the plug into the coupling and you're done\nStep 7: Assembling the Whole Cover\nWe connect the bottom, pipe and plastic adapter together\nStep 8: Modifying the Cover\nTo make the cover easier to insert, you can cut the bottom ring at the rubber adapter\nStep 9: Everything Is Ready! Nearly :)\nIf you do not want to paint, then you can already use it. We just put the skewers in the cover and that's it. I still recommend watching step 14 :)\nStep 10: Preparation for Painting\nWe disassemble everything. We do not disassemble only the bottom, we will paint it as a whole. We remove the rubber adapter, as it is not necessary to paint it.\nWe process all surfaces for painting with sandpaper, so the paint will fit better\nStep 11: Priming\nIf not primed, the paint will not adhere. I took an automotive primer for plastic.\nStep 12: Painting\nRead the instructions for your paint carefully. I covered everything with a thin layer 2 times. This helped to avoid smudges.\nStep 13: Putting It All Back\nAfter the paint has completely dried, you can put the cover back\nStep 14: Let's Modify the Cover a Little More\nIn order for the tightness not to interfere with closing the lid, you can cut out small areas in the O-rings on the lid. It is better to leave the top ring intact, it will cover from dust\nStep 15: Now It’s Ready for Sure\nThat's all, a cool, handy, hand-made thing is ready! And you are amazing!\nAnd your skewers are now neatly and compactly packed, taking up little space.", "819" ], [ "Bending Wood / MDF\nIntroduction: Bending Wood / MDF\n“Where the curve starts a proper earning ends” my grandfather, a carpenter by trade, used to say.\nWell, after some experience gained I totally agree with him. Compared to angular joints curvy and bendy shapes made of wood take an infinite time longer to make. The best way to bend wood and medium-density fibreboard is by the use of steam. Since I don’t have a steam chamber I was looking for an easier way for an aspiring project, the make of a flowerbed for my balcony.\nThis Instructable shows a technique almost forgotten – shaping wood and medium-density fibreboard by watering it and the use of ammonia.\nSupplies\nThose are the things you need:\n* several clamps\n* Ammonia (I used a 10% solution)\n* spray can\n* tension belt\n* wood glue\nPLEASE NOTE: ammonia solution, or ammonium hydroxide, to be precisely, is an extremely hazardous liquid. It was widely used as a household cleaner until a couple of decades ago. The stench is almost unbearable.\nAlways wear goggles, gloves and a mask and apply it only on the outside!\nStep 1: Soaking the Wood / MDF\nThe principal idea is to bend small layers of wood and / or fibreboard, let them dry and then glue them together.\nFirst I sprayed the cut pieces with a 10% ammonia solution on both sides. I did this twice and let everything dry for a day.\nThen I watered the pieces.", "254" ], [ "The strong stench of the ammonia is nearly gone, I did this in my shower cabinet.\nStep 2: Bending It in Shape\nAfter the soaking I bent the pieces around the shape they should take and fixed everything with clamps.\nI left it that way for a couple of hours, then took it off and fixed it by the use of a tension belt. This is for letting the material dry off, also for keeping the shape (it would otherwise go back to almost normal).\nStep 3: Glueing Everything Together\nA day later you can start glueing everything together. Take wood glue and coat the entire contact area. Again put it around the shape or a pattern and press it as strong as possible together. Let it rest for 24h and take it off.\nSometimes some smaller spots on the edge between the layers didn’t properly stick together. I inserted wood glue into the gaps and pressed it again with a clamp.\nStep 4: Finishing\nI made the bent part of the flowerbed out of two layers of MDF, about 8 mm thick, and a thin layer of wood with a thickness of about 2 mm. The latter was for the visible surface, it shall match with the other parts of the construction.\nIMPORTANT: Since it is almost impossible to measure the proper length of a curve before, make sure all the pieces are a bit oversized and do the cutting later in place.", "556" ], [ "Oven Mitt From Recycled Materials\nIntroduction: Oven Mitt From Recycled Materials\nI saw that my friend's oven mitts were beyond repair, so I decided to make him some new ones.\nEverything I needed was found in my storage boxes, and in the kitchen I found an oven mitt to serve as an example.\nI used the following materials:\nFor the outer side\n* some leather from an old sofa, that I kept because the reverse side of the boring leather turned out to be a beautiful blue suede\n* jeans with worn knees, 100% cotton\nFor the padded lining\n* a duvet (or comforter) that was torn, made from non-woven fabric 100% polypropylene, and a filling from 100 % polyester (already 100% recycled)\nAlternatively, you can use old towels, shrunken wool sweaters or cotton woolfor the padding, and for instance a cotton shirt for the lining.\nTools I used:\n* a sewing machine\n* thread and pins\n* scissors\n* a marker\n* an iron and ironing board\nStep 1: Fabric and Pattern\nFABRIC:\nYou will need pieces of approx 38 x 26 cm or 15 x 10 1/4 inch.\nSpacious pieces of fabric make it easier to trim the excess fabric later.\n* fabric of choice for the 2 outer layers.\n* insulation or padding. Although the leather offers some heat protection, more protection doesn't hurt. I used the filling from the duvet.\n* lining. I used 2 layers of non-woven fabric from the duvet.\n* some bias binding or twill tape for the loop.\n* fabric or ribbon to finish off the opening.\nPATTERN:\nDownload the PDF. It's at the bottom of this step. Print the document and make sure it's printed on a 100% scale. Tape the pages together, there are marks to make it easier.\nCut out the pattern.\nIMPORTANT:\nIf you follow this instructable correctly, you will end up with a left-hand mitt. To make it right-hand, just switch the leather and jeans layers.\nStep 2: Preparing the Padded Lining\nPin the paper pattern on a piece of non-woven fabric and follow the contours with a marker.\nThen pin together a layer of non-woven fabric, padding, and another layer of non-woven fabric.\nStitch a few lines across to hold them together.", "316" ], [ "There is no need to be very exact at this point.\nRepeat this step for the other padded lining.\nStitch one part together with a narrow hem, following the contours of the marker lines, and trim this part roughly.\nStep 3: Putting the Layers Together\nNow it's time to stitch all layers together.\nFold a ribbon and put it between the middle layers to create a loop. The loop must point inwards.\nPlace the pieces in the following order (i.e. Right sides together):\nPadded lining / Leather / Folded Ribbon / Jeans / Padded lining.\nStitch together with a 5-7 mm hem, but not at the bottom!\nStep 4: Cut Out and Zigzag\nCut off the excess material.\nZigzag around the hem. Again, not at the bottom!\nStep 5: Turn Inside Out\nTo turn the mitt inside out, put your hand between the middle layers. Push the outside inward with your other hand.\nIt is best to start with the thumb.\nStep 6: Finishing Off\nYou can finish off the opening with bias binding, or twill tape, which is much easier than making this colorful finish I made because it matched the colors of my friend's kitchen. But if you want to:\nCut off a piece of fabric, about 5 x 40 cm or 2 x 15 3/4 inch.\nZigzag it.\nFold a 1-1.5 cm hem. If it doesn't stick, iron it. Fold over a hem at one 5 cm side.\nStitch it to the inside, beginning with the hemmed side.\nFold it over, and stitch it to the right side, making a folded overlap at the end.\nStep 7: Ready\nOne beautiful left-hand oven mitt.", "748" ], [ "PVC Tensegrity \"Pipe Burst\"\nIntroduction: PVC Tensegrity \"Pipe Burst\"\nTensegrity! An object made from drain pipe leftovers! It's a bit magical how the physical conditions create a tension that makes it a unit. At first sight a bit confusing ... you have to look twice to understand the principle.\nThe trigger for this project was the \"PVC“ - Speed Challenge!\nSupplies\nI still had some drain pipes left over from a bathroom renovation. For example a toilet bowl connection piece (Ø 110 mm), a wrong buy because the angle didn't fit ... and a lot of drain pipe pieces (Ø 40mm). Enough material to realise my idea!\nFurthermore, I needed\n* Metal saw\n* Miter saw\n* PVC glue\n* Sandpaper\n* Cutter knife\n* Nyon thread Ø 0.35mm\n* Preserving jar rubberring\n* Sewing needle\n* 4 screws Ø m 2.4 x 12 mm and matching nuts\n* Drill bits Ø 1mm and Ø 2,5mm\n* Screwdriver\n* pliers\nStep 1: Sawing Upper and Lower Ring\nFor this step I needed:\n* PVC pipe Ø 110 mm\n* Metal saw\n* Cutter knife\n* Sandpaper\nFrom the white connection pipe for toilet bowls (Ø 110mm) I sawed 2 rings of 30mm width.\nAs this pipe does not fit into my miter saw, I had to use a normal metal saw for it. It was not easy to saw absolutely right-angled with it. Then I cleaned the edges with a cutter knife and sandpaper.\nStep 2: Sawing and Glueing Pipes\nFor the next step I needed:\n* about 70 cm PVC pipe Ø 40 mm\n* Miter saw\n* Cutter knife\n* Sandpaper\n* PVC glue\nI sawed 2 tubes to size 175 mm length. One side straight cut (90°) and one side 45° cut and 2 tubes to size 115mm length. Both sides 45° cut.\nAgain, I cleaned the edges with a cutter knife and sandpaper.\nThen I glued the 45° side of the longer tube to one of the 45° sides of the short tube.", "582" ], [ "You have to make sure that it fits well! I did the same with the other two tubes. It had to harden for a few hours!\nStep 3: Drilling Holes Upper and Lower Ring\nNow I needed:\n* fine marker\n* Ø 1mm drill\n* Ø 2.5mm drill\n* piercer\nFor design reasons I decided to use a 5 thread tensegrity structure. One retaining thread and 4 threads for stabilisation. 3 threads for stabilisation would also have been enough, but I didn't think it was appropriate.\nWith the help of the drawing you can determine the points for the 4 holes for the nylon threads and the 2 points for the attachment to the tube. I placed one of the two rings on the drawing and marked the points with a fine felt pen at a height of 10mm on the ring.\nFirst I drilled the 4 holes for the nylon threads with a Ø 1mm drill and then the two holes for the attachment to the tube with a Ø 2.5mm drill (8mm from the edges of the ring). I prepared the drill points with a piercer!\nStep 4: Drilling Holes Pipes - Attachment to the Rings\nFor this step I needed:\n* fine marker\n* Ø 2.5mm drill\n* piercer\n* 4 screws Ø m 2.4 x 12 mm and matching nuts\n* pliers\nFirst I marked the two holes at a distance of 8 and 22mm from the edge (at the highest point of the rounding!). Make sure that the angle pipe is absolutely vertical.\nAfter I have drilled the holes I attached the ring to the tube with 2 screws Ø m 2.4 x 12 mm and matching nuts. Of course, you can also use a different screw size, but then you have to adjust the hole size accordingly.\nI did the same with the 2nd ring and the angle pipe.\nStep 5: Holes for Suspension Thread\nNow I needed:\n* fine marker\n* Ø 1mm drill\n* piercer\nIn order for the tensegrity principle to work, the holes must be set as precisely as possible. This means that the suspension thread should later sit exactly in the centre of the rings. As the rings have a diameter of 110mm, the centre is at 55mm. Accordingly, the drilling points must be set at the lowest or highest of the pipe (see drawing).\nStep 6: Attaching Suspension Thread\nFor this step I needed:\n* Nyon thread Ø 0.", "56" ], [ "Toilet Roller Bearing\nIntroduction: Toilet Roller Bearing\nThis toilet roll holder greatly enhances the unrolling experience of toilet paper.\nA fusion project of a bicycle hub and lavatory paper to enroll in the Modify It Speed Challenge…\nSome words on the design: the outer diameter of a bicycle axle flange matches well to the inner diameter of a toilet roll. The ball bearings in the hub make it a high-grade toilet paper holder, indestructible and stylish - especially for bike lovers and bicycle repair(wo)men.\nStep 1: Usage\nFrankly speaking the smooth unrolling is rather a drawback than an advantage: imagine the bunch of paper on the bathroom floor. To slow the unrolling down a bit the ball bearing nut may be tightened somewhat, resulting a some additional friction inside the ball bearings.\nStep 2: Making\nFixing the spindle can be done easily using a hook iron: preferably a short-sided one to prevent seeing it behind the paper roll. And make sure to leave one side open to change the toilet roll. As there is no standard size for toilet roll dimensions try to find a toilet paper brand that matches the size of your leftover bicycle hub. A tight fit of the toilet roll to the spindle is preferable, to avoid it from running down.", "226" ], [ "Or adapt the hub diameter, see the next step.\nStep 3: Adapting the Hub Diameter\nThe diameter of the axis flange may be reduced by filing. The pictures show how this has been done using the hub's rotating capabilities: a drill is driving the spindle through a rubber coupling sleeve, and a flat file is applied manually (use an old file or perhaps sanding paper). In this way the diameter was easily reduced from 46 mm (1.81 in) to 45 mm (1.77 in), resulting in a tight fit of the toilet roll. Also, the flange was curved a bit to make exchanging the roll smoother.\nStep 4: Let’s Roll...\nThe time-lapse movie endlessly shows the unrolling of the paper. In reality it runs super smoothly of course.\nStep 5: Other Instructables by Openproducts\nWow – this is the 50th Instructable by Openproducts!\nHere links to the best ones so far:\n* Bike Rim Chandelier\n* LED Replacement in Bicycle Headlight\n* Easy Cable Clip - Sucker Version\n* Colander Effect Lamp Using a Magnifying Glass\n* CountClock for kids: intuitively learning to tell the time\nIf you like to see all then check out the Openproducts Gallery.\nStep 6: That’s All\nAnother time lapse movie closes this Toilet Roller Bearing Instructable, published in October 2020 under Creative Commons Attribution by Openproducts.\nBut wait!\nIf you like this work then share the info on Twitter (https://twitter.com/openproducts) or Instagram (https://www.instagram.com/openproductsdesign). Thanks...", "438" ] ]

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[ [ "The answers above are fairly comprehensive, so I will just add a point by way of analogy which I think gives an intuition for why physicists (and scientists in general) prefer simpler theories and tend to be more inclined to believe they are somehow fundamentally correct if they give the right predictions.\nIt is common in science to have to perform \"curve fitting\", where one has many sets of measurements (to give a concrete example, let's say we have 50 measurements of the force between two newly discovered particles and the distance between them), generally with some noise and measurement error, and must determine how well they agree with some model. In our example, we might have a model of force where $F(r) = \\frac{a}{r^2}$. Here we have a single parameter, $a$, so we have to answer two questions - which value of $a$ makes the model best fit our measured data, and once we've found it, how well does it fit? Usually it won't fit perfectly even if the model was correct because the measurements are never perfect, but generally the better the fit the more confident we can be in the model. We may compare two models by asking which can be made to better fit data.\nHowever we must be careful with this line of reasoning, because of a phenomena called \"overfitting\". Let's say someone else comes along and claims that the force is described by a 100th degree polynomial, i.e. $F(r) = a_{100}r^{100} + a_{99}r^{99} + a_{98}r^{98} + ... + a_2r^2 + a_1r^1 + a_0r^0$.", "484" ], [ "As it turns out, given any set of $n$ pairs of measurements, we can perfectly fit that data with an $n$th degree polynomial, so that means our 100th degree polynomial can be perfectly fitted to our 50 measurements.\nBut obviously this doesn't mean the model is correct, in the case of our two new particles, because we could have always fit those data-points regardless of the underlying physics. This is known as \"overfitting\". This is also why most judgements of how well a model agrees with data don't just account for how closely it fits, but how many degrees of freedom the model had to fiddle with.\nIn general when discussing physical theories we may not have lots of easy to count numerical parameters. Whether one theory or the other has greater or fewer metaphorical parameters is non-obvious, and two theories where one seems more complicated may turn out to be mathematically, or even conceptually identical. Thus physicists are forced to rely on an intuitive sense of \"elegance\", a gut feeling that says a theory is \"simple\", \"inevitable\", that it is either right or wrong and can't be easily modified to fit observations that disagree slightly. I believe <PERSON> once summed up the feeling when he said something like \"You can't put imperfections on a perfect thing, you have to come up with a new perfect thing instead\". Perhaps one day we will figure out how to quantify this idea, but for now we're stuck with our guts.", "484" ], [ "Let me give a vague analogy to illustrate the issues in talking about observation.\nImagine that I have just thrown a stone into a pond and I ask you, can you see the wave it makes? You say, yes of course, why? I say, no you didn't really see all of the wave. You only saw what you saw from your position and angle. And is what you saw the wave? Or is it just an image of the wave that is in your mind? How do you even know that that image is an accurate reflection of the actual wave? In fact we know our eye has a limit on its resolving power and its sensitivity.\nSo you didn't actually see any wave. You just saw something which both of us do call a \"wave\" in English. The word is merely a reference to the entity, not the entity itself. You might ask, is it possible to observe an entity directly and not through any intermediate instrument such as our eyeball? But what really is \"directly\"? If your mind can somehow touch the wave (with what, may I ask?), is it enough for you? Or is your mind itself merely an instrument which you use to interact with the world?\nAnyway that dives straight into the deep end of philosophy, though you'll have to somehow answer that before you can specify precisely enough what you mean by \"observe\".\nOn the other hand, what if we both agree there was a wave, and I then ask you, what is the position of the wave? And you stare blankly at me. But that might well be the same question you would be tempted to ask about an electron. What if the electron indeed has an underlying reality that corresponds more closely to its wavefunction rather than a single point in space? Do you even have the slightest evidence that it is more like a point? No.\nYou could say, let's take the highest point of a water molecule (assuming it's sufficiently point-like) as the position. If so, then it's not going to have any nice properties at all, and would randomly jump around the pond. A better idea would be to take the average position of the water molecules that are above the average water level of the pond.", "795" ], [ "Then we can 'see' that it moves in the direction of the wave more or less along with the crest. We can even touch the wave crest as it goes past, which means that we can sort of estimate the position as defined this way. There is some uncertainty here, not unlike the uncertainty you see in measuring the position of a classical wave packet or in measuring the position of a particle (<PERSON>'s uncertainty principle), in the sense that despite the position of a pond wave being well-defined (assuming point-like water molecules or more generally some mass density function for the water), we cannot even classically measure it accurately because anything we do will disrupt the wave.\nSimilarly, we can define velocity of the wave as the flux, the average flow of the water (according to the evolution of the mass density function over time). As with position, we cannot even classically measure the velocity accurately without changing it.\nNow, we could go another way around the problem. Instead of trying to observe all of the wave at once, we repeat the stone throw many times, and each time we observe just one small part of the wave. Of course, now that we are skeptical we'll question whether we really can repeat something in exactly the same way each time. It's of course impossible in general but we hope it's not too wildly different.\nThis is exactly what scientists have done in order to observe (in this sense) the wavefunction of an electron. It was done very long time ago, and I do not know the history, but supposedly IBM was one of the first to arrange impurity molecules on a metal surface and then using a Scanning Tunneling Microscope to image the electron density. They have some pictures here, including the well-known quantum corral:\n(http://researcher.watson.ibm.com/researcher/files/us-flinte/stm16.jpg)\nI do not know whether they edited the raw data (highly likely, when I did it before I had to edit to remove noise and artifacts from the imperfect STM tip). There are other images on the internet like:\n(http://nisenet.org/catalog/media/scientific_image_-_quantum_corral_top_view)\nBut of course all colour or 3d effects in STM images are computer generated. Recently (2013), some have claimed to be able to image atomic orbitals, such as:\n(http://physicsworld.", "795" ], [ "Do electrons change orbitals as per QM instantaneously?\nIn every reasonable interpretation of this question, the answer is no. But there are historical and sociological reasons why a lot of people say the answer is yes.\nConsider an electron in a hydrogen atom which falls from the $2p$ state to the $1s$ state. The quantum state of the electron over time will be (assuming one can just trace out the environment without issue) $$|\\psi(t) \\rangle = c_1(t) |2p \\rangle + c_2(t) | 1s \\rangle.$$ Over time, $c_1(t)$ smoothly decreases from one to zero, while $c_2(t)$ smoothly increases from zero to one. So everything happens continuously, and there are no jumps. (Meanwhile, the expected number of photons in the electromagnetic field also smoothly increases from zero to one, via continuous superpositions of zero-photon and one-photon states.)\nThe reason some people might call this an instantaneous jump goes back to the very origins of quantum mechanics. In these archaic times, ancient physicists thought of the $|2 p \\rangle$ and $|1 s \\rangle$ states as classical orbits of different radii, rather than the atomic orbitals we know of today. If you take this naive view, then the electron really has to teleport from one radius to the other.\nIt should be emphasized that, even though people won't stop passing on this misinformation, this view is completely wrong. It has been known to be wrong since the advent of the <PERSON> equation almost $100$ years ago.", "187" ], [ "The wavefunction $\\psi(\\mathbf{r}, t)$ evolves perfectly continuously in time during this process, and there is no point when one can say a jump has \"instantly\" occurred.\nOne reason one might think that jumps occur even while systems aren't being measured, if you have an experimental apparatus that can only answer the question \"is the state $|2p \\rangle$ or $|1s \\rangle$\", then you can obviously only get one or the other. But this doesn't mean that the system must teleport from one to the other, any more than only saying yes or no to a kid constantly asking \"are we there yet?\" means your car teleports.\nAnother, less defensible reason, is that people are just passing it on because it's a well-known example of \"quantum spookiness\" and a totem of how unintuitive quantum mechanics is. Which it would be, if it were actually true. I think needlessly mysterious explanations like this hurt the public understanding of quantum mechanics more than they help.\nIs this change limited by the speed of light or not?\nIn the context of nonrelativistic quantum mechanics, nothing is limited by the speed of light because the theory doesn't know about relativity. It's easy to take the <PERSON> equation and set up a solution with a particle moving faster than light. However, the results will not be trustworthy.\nWithin nonrelativistic quantum mechanics, there's nothing that prevents $c_1(t)$ from going from one to zero arbitrarily fast. In practice, this will be hard to realize because of the energy-time uncertainty principle: if you would like to force the system to settle into the $|1 s \\rangle$ state within time $\\Delta t$, the overall energy has an uncertainty $\\hbar/\\Delta t$, which becomes large. I don't think speed-of-light limitations are relevant for common atomic emission processes.", "795" ], [ "The answer to this is a bit nuanced so I have now edited the answer to make it as clear as possible.\nThe big picture is: Yes, it is possible to measure a wave function, if it is possible to find or produce particles with that wave function so that repeated measurements can be made (not on the same particle each time, but on a different particle which is known to have the same wave function). This can be done in practice. For example, this experiment effectively measures the magnitude of the wave function in momentum space for an electron in a hydrogen atom: source.\nIf you write $$\\psi(\\vec{r})=A(\\vec{r})e^{i\\alpha(\\vec{r})}$$ For $A,\\alpha$ real, then $A$ can be determined by measurements of position, and I believe it is possible to find $\\alpha$ only from momentum measurements up to a constant offset $\\alpha(x) \\to \\alpha(x) + c$. Because of this constant offset which is not measurable, $\\psi(\\vec{r})$ is not measurable at a point, but $|\\psi(\\vec{r})|^2 $ is, $A(\\vec{r})$ is, and $\\alpha(\\vec{r})$ is up to that \"offset\", which is called a global phase.\nOf course, any finite number of measurements will only give information on a finite number of points of $\\psi(\\vec{r})$, each with uncertainty as well, especially because many measurements are necessary to measure a probability. These measurements must be done by repeatedly preparing a particle in that wave function and then measuring at a chosen later time. The experimentalist does not need to know what the wave function is beforehand, she/he must only know that the wave function is the same for each particle. Then, she can interpolate in between the measured points to come to a good guess for $\\psi$ at all points. In practice, any experimental outcome which is predicted by $\\psi(\\vec{r})$ can also be used to constrain it.\nThere is a practice of measuring states called Quantum Tomography. It has its own wikipedia.", "795" ], [ "It is usually used for finite-dimensional systems. But in reality every system is infinite dimensional, one only treats them as finite-dimensional. One could treat the position space wave function in the same way.\nThat being said, though it can be done in principle, I'm not aware of a full tomography which has been done in practice. If one really doesn't exist, this is a severe experimental weakness of testing the theory in my view. If anyone has a source to one, I'd be interested. I know of many momentum experiments where the fourier transform of the wave function was in fact checked, but not the entire thing.\nI will point out again for clarity, because it seems that others are of the opinion that I have not emphasized this enough, that if you do not have the ability to find or produce many particles in the unknown state $\\psi$ then it is not possible to measure in practice. It seems to me, though, that a clever setup could be used to measure almost any wave function in principle. Whether technology has reached that point is another question. But I will do due dilligence and flag that last statement as opinion, because I cannot provide references or proofs that it must be so.", "795" ], [ "Bound states\nIn retrospect the below answer is a bit long winded, so I will summarize the basic point: to get \"orbital\" motion, one simply needs that some object is trapped in the potential well of another, meaning it doesn't have enough kinetic energy to escape. If the potential well is rotationally symmetric then there will be conservation of angular momentum, and if the potential has $1/r$ dependence then the orbits will be Keplerian (at least classically), but that is not necessarily important. All that matters is that you can have a hierarchy: some objects A, B, C, . . . with decreasing \"charges\" (e.g. gravitational mass, or electric charge) $m_A\\gg m_B \\gg m_C$, . . . with separation distances $r_{AB}\\gg r_{BC}\\gg$ . . . so that B is trapped in the potential well of A, C is trapped in the potential well of B, etc. In the example below, I chose A=galactic core, B=a star, C=a planet, D=a moon (and a satellite can orbit the moon, and in principle even something very tiny could orbit the satellite, but it would be so weakly bound that tiny perturbations would give it enough energy to escape).\nThe quantum mechanical version of what I am describing is a bound state. Quarks are bound (by the strong force) into hadrons (protons and neutrons), which are bound (again by the strong force) into atomic nuclei, which form bound states with electrons (via the electromagnetic force) to make atoms, which can further form bound states (by chemical bonding, which is electromagnetic in origin) to make molecules, and so on until you get to sizes where electric charge is screened and Newtonian gravity takes over as described in the paragraph above and the original answer below.\nOriginal answer below\nThere are many potential directions in which your question could be interpreted and answered. One, which comes from a physics perspective, is symmetry.", "187" ], [ "In this case, rotational symmetry. The laws of physics are rotationally invariant, and as a consequence of <PERSON>'s theorem, angular momentum is a conserved quantity.\nIn orbital mechanics specifically, one generally is dealing with central potentials, e.g. the potential energy of a massive object moving around the sun only depends on the distance from the sun (and decays is one over distance). Since this potential does not depend on the angle one makes with any particular axis through the sun, it is rotationally symmetric and thus angular momentum is conserved. (A note: although it is true that electrons do not \"orbit\" atomic nuclei, they still have conserved angular momentum!)\nNow to the different scales portion of the question. At the scale of planetary motion, gravity is the only important force to consider, all other forces are essentially completely screened at this scale (because the relevant objects, e.g. asteroids or planets, are charge-neutral). The motion of the objects in the solar system relative to each other can, to a good approximation, be approximated by only considering the gravitational force of the sun, as described in the previous paragraph. Inter-object forces (e.g. gravitational attraction between planets) can be treated perturbatively.\nSimilarly at other scales, e.g. a single planet gravitationally interacting with its moons can be approximated to a good approximation as a collection of two-body problems. Each object orbits in the near-spherically-symmetric potential well of the nearest object which has a mass orders of magnitude larger than itself, and the gravitational attraction of smaller nearby objects act only perturbatively relative to the dominant nearby attractive body.\nLet me try to be slightly more precise about that. Let's start at a large scale: the solar system orbits around the galactic core. For simplicity let's model the galactic core as a point mass.$^\\dagger$ The solar system is about $10^{20}$ meters from the galactic core, and has a radius of about $10^{10}$ meters. The size of the solar system relative to the size of the galaxy is about the same as the size of an atom relative to the size of your body, so we can treat it as a point mass. Treating this as a 2-body problem, the gravitational potential that the solar system orbits in might look something like this:\nwhere $a_{\\mathrm{galactic}}$ is a lengthscale on the order $10^{20}$ meters. But of course, the solar system itself is made of a bunch of small massive objects, the largest of the which is the sun, and so itself has a gravitational potential.", "319" ], [ "The answer depends somewhat on the interpretation of quantum mechanics you choose. However, if you take one of the standard ones, then a superposition of two states is not the same as being in both of these states simultaneously, nor as being in an unknown one of these states, nor as being in an unknown state \"in between\". Superposition is an entirely new idea that we don't have words in conversational English to express.\nIt might help to give a real-world example that mirrors the math. You can drive your car in any direction. Suppose your car also has a widget that indicates what compass direction you're moving in, but it's primitive and can only say \"North\", \"East\", \"South\", or \"West\". These are the only four things it can ever say.", "28" ], [ "If you drive northeast, it has a 50/50 chance of saying North or East. Now I'll reframe all your questions in this context and the answers should be clearer:\nHowever, I'm wondering if before the measurement, i.e. during superposition, the quantum really is in those two different pure states ($|0\\rangle$ and $|1\\rangle$) - or maybe even in all states in between those two?\n\"I'm wondering if, when you drive northeast, the direction of your car really is in these two different pure directions (North and East) - or maybe even in all directions in between those two?\"\nor if it is always only in one \"pure\" state (or one state between those two)\n\"Or is the car always going one \"pure\" direction, like North or East?\"\ncould the dice 1) show all numbers at the front side at once before measuring it and the measurement destroys this so that it only shows one of those sides then or 2) is there always only one number at the front side, but we talk of superposition because we don't know, which one until measuring it?\n\"1) Could the widget say North and East at the same time before looking at it? 2) Is the direction of the car always North or East, but we don't know which one until measuring it?\"\nHopefully the answers to these questions are clear. The car can drive any way it wants to; the widget just doesn't tell us everything about the state, just like measuring if a quantum bit is 0 or 1 doesn't tell us everything about its state. Driving steadily northeast is just a fundamentally different thing from driving north and driving east and is not at all a probabilistic mixture of them. This is the way standard quantum mechanics thinks of superpositions.", "680" ], [ "At an in-principle level, no, it doesn't change the laws of physics, but it could change how we write the equations we use to describe them.\nThe laws of physics depend on the dimension Time. Any given clock is simply an instrument to measure time. The standard scientific unit, which we measure in, for time is the second.\nThe second is currently defined based on the vibration of certain atoms, but was originally defined as a fraction of an minute which was in turn defined as a fraction of an hour and so on - ultimately the second was originally based on the rotation of the earth. This could be considered one \"clock\" in the way you mean, if i understand you correctly.\nChanging the definition to be based on atomic vibrations allowed a more accurate definition of the size of the unit, but didn't change any fundamental physics, which ultimately relate to the dimension, time. Choosing to define it based on the vibrations of a different atom wouldn't have changed anything except the ease/accuracy/reliability with which we could measure the unit.\nIf you mean choosing a different unit size, other than what we currently know as a second, that would either have resulted in different choices of other unit sizes, or different looking fundamental equations - but they would only have differed by the constants needed to make the units work.\nTake <PERSON>'s Second Law.", "432" ], [ "The fundamental law is that force is equal to the rate of change of momentum. Given constant mass, that results in the familiar $$ F = ma $$ This is given use of kg for mass and meters per second per second for acceleration. However, if we wanted to measure acceleration in miles per hour per hour we could. The equation would then be $$ F = Kma $$ Where K is a constant (approximately 8052.985) to make the units work. The fundamental physics is the same.\nIn this case, we pretty much define the unit of force (Newtons) so that this holds (i.e. so that the constant K = 1 and can be left out altogether)\nIn practice, it would probably have resulted in changes in some other units to make things nicer, rather than just shoving in a bunch of constants.", "131" ], [ "I think the most simple answer is just \"magic\", and ignorance:\nFor one, during the last few centuries \"magic\" that was previously widely accepted to exist \"disappeared\" as science somewhat took its place. The coffee machine you use every morning would have been clearly \"magic\" just a few hundred years ago. But is it magic to you? - So, whatever advanced we encounter daily in our time was definitely magic in ancient times.\nFrom there, it's only a small step to saying that there used to be magic in ancient times which is now gone.\nAnd here comes ignorance into play. Through historical records, pictures, paintings, films,...", "111" ], [ "we (believe to) have a pretty clear picture of what the world, and life, was like a hundred years ago. Or two hundred years ago. But the world of, say, 3000 years before our time is much less documented and thus by itself quite mysterious.\nSo we have a world about which we don't know much, where the existence of magic was wide-spread common sense, from which we may find a rare artifact.\nOr, seen more pragmatically, if, as a world builder, we want something magic, where do we take it from in the most plausible (or easiest) way? How about a mysterious world which we have no access to, where magic is a common thing and from which artifacts can reach us without too much hassle (compared to, e.g., extra-terrestrial devices or things from the future)?\nOne could have some character craft something akin to magical in our time, but that is harder to make plausible because people have a grasp of what technology today can do. So instead of trying to create a somewhat credible background about why or how man's current capabilities enable something magic-like without violating what people know you can just take an artifact from some place about which the common person, or everybody, knows little except that it definitely exists.\n(I deliberately used the present tense above to describe ancient times, because w.r.t. the (desired) effect the ancient world is a mystical world, perceived like a place you just can't go to.)", "111" ] ]

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[ [ "Land of Bad\n5:00 pm\nTitle of Bad\nNot as bad as I expected. Not necessarily a good movie, I was just entertained as hell watching this dad movie. They can’t keep making these dad movies it’s cheating. Dad movies know how to entertain me. Even when they’re not very good. To give this credit, it’s competent. I was expecting the filmmaking to be way worse. I really love that the villain gets a proper beatdown.", "241" ], [ "So many movies have the villain just get shot once and that’s the end. This movie they beat the fucking shit out of the bad guy and it’s so satisfying. The thing that really holds me back from saying it’s a good movie is because of how bad the dialogue is whenever the characters are casually talking about not important things. <PERSON> did not do that great of a job, especially when he has to (or at least) show emotion. There’s also a lot of stupid far fetched things in this movie. The thing that really carries this movie for me is that it’s just pretty entertaining. It’s not a very good movie but it’s an entertaining one. For that reason I can’t confidently give it a definitively good score. I was expecting to say Movie of Bad, but I turned out to not actually hate this.", "217" ], [ "<PERSON>\nI wanted to hate this, but I didn’t wow. This definitely isn’t a great movie it’s just ok. But that’s a godsend considering what I thought it was gonna be by its terrible trailer. There are a lot of cringy lines and very cringy moments that make me wanna jump off a building.", "170" ], [ "It’s probably leaning on a 5 instead of a 7 if I had to change its score personally. But who cares, it’s a fine movie tbh I had a good time with it. Will people come out hating it… yeah. This will basically be the Last Jedi of the Pixar pantheon. But I for one enjoyed it and I didn’t hate it.", "596" ], [ "In the Summers\nSundance 2024: Film #29\nOne of my favorites of this year’s festival. Probably my second. When I watch movies that are slice of life and not conventionally structured I get absorbed in the film and forget I’m watching a movie. Then the runtime flies by. This is definitely one of those cases. This is a very three-dimensional film. Not just because of the way it’s presented but also because it is such a good script. There’s lots of very subtle blink and you miss it moments that call back to previous scenes and adds to character arcs. All the acting in it is great too.", "462" ], [ "All the child performances, as well as <PERSON> who plays the complex father character. There were only a couple scenes towards the beginning that I felt were a little too overdramatic, but the rest of the film was totally subtle. I like that the father is not so clearly good or bad. It’s complex and it’s realistic. I thought this was pretty great. This is something that I would totally watch again. Especially in a movie theater where I can just sit and forget where I am.\nI’m really surprised at how great this movie was. I was looking forward to it, but I didn’t think it would be this well done. It has no acquisition yet and no future release date but I hope it comes out soon because I’d like to see it again. On to my final film…", "657" ], [ "<PERSON>\n1:25 pm\nIf any of you live in the Midwest like I do then you’re probably being hit right now with or are going to be hit with a massive blizzard. It is so incredibly bad here that almost every place is closed. I pretty much risked my life to watch this movie I was excited for. I watched the earliest show I could, and by the time it was done the theater was closed.\nThe Harder They Fall was a film that I was very surprised by as I knew nothing about it before seeing it. I thought it had a lot of flaws, but it was good and the movie just gets better from memory. That movie had an absolutely killer soundtrack too. I think that film has a better soundtrack than this movie does but the soundtrack for this movie is still really good. I think that’s the only thing that this film has that I think is better than The Harder They Fall. Or at least personally enjoyable. This sophomore film may be criticized by some for not being as good as The Harder They Fall. I won’t deny that this movie has quite a bit of flaws.\nI think people are going to heavily criticize the lack of some character development. Some people may say that this film bites off more than it can chew. I won’t necessarily argue with that but I just thought that this movie is super entertaining and really enjoyable.", "292" ], [ "I love the cast. I think the cinematography looks great. I thought it was really funny and I just really like the story. it’s a simple as that. I’ve really like the story. I also really like the messages of this film. Honestly, if all faith based movies were like this, I’d be a few steps closer to not being an atheist. I’ve heard the criticism that this movie feels too long and I don’t think I agree. I didn’t feel long to me. It’s two hours and 16 minutes long and it only felt like about 100 minutes for me.\nI really really enjoyed this movie. I think it’s a really good sophomore feature. I think the ending is amazing and there’s tons of great scenes and I would totally watch this movie again. It was worth driving on the worst conditioned roads ever.\nThis movie also got me thinking, what if The audience for this film was as obnoxious as the people who use movies like Sound of Freedom or Lady Ballers as a victory flag? “The movie conservatives don’t want you to see” lmao", "823" ], [ "The Lego Movie\nSo crazy to me that this is now 10 years old. I’ve loved movies since before I could speak or remember, but this film is what got me to actually think about the movies I watch. It was is the first film I saw that got me to engage with movies rather than look at it as a fun little pastime. This is my favorite animated movie ever. My top four isn’t necessarily my actual top four.", "462" ], [ "It’s hard to pick a favorite movie. I never have an answer to that question, but this film has consistently been at the top. So I feel if there were numbers to run then this would technically be my favorite movie. This movie is amazing and way way more intelligent than it has any right to be. For some reason people still say “it’s just a kids movie.”", "462" ], [ "Girls Trip\n1:00 pm\nEvery once in a while a shitty movie that has clones like it that are poorly received will just get high praise for no reason. Girls Trip is one of those for me. I’m sorry but what do people like about this? The praise is absurdly high for what we’re given. The cinematography is terrible. The music is repulsive, distracting, and ruins the already unfunny scenes. The acting sucks. Almost every comedy scene feels forced. They have to stretch reality so much to make these ridiculous jokes fit into a scene. It’s not like it’s intentionally absurd or anything. It’s not grounded and it’s not absurd. It’s just this stupid spot in the middle. It’s just so dumb. It’s just Grown Ups. Nothing happens, the characters screw around, the cast and crew go on vacation while making it and it expects the audience to just have fun. What is fun? It looks like fun to be at the 2016 Essence Music Festival. I wish I was there instead of having to watch other people have fun there. I thought surely because this is so highly praised that even though I wouldn’t like it, I’d at least see the angle that people like. Nope. It’s just another worthless portly made comedy that has great reviews for some reason.", "292" ], [ "People just say “it’s fun” which is okay I guess but like how? What’s fun? I can call any movie fun. I guess all you have to do is just film your vacation and don’t forget to put a couple of fake ass forced emotional scenes in it and it’ll get praise. I don’t know man I don’t know. Good for you all. Enjoy it. Not my thing, sorry. If I was watching it at home I would’ve turned it off about 30 minutes in because the film feels like an eternity with it’s non-structure. It’s feels three hours long. I’m not being hyperbolic. If I didn’t know the runtime I would’ve genuinely guessed three hours. This has absolutely no business being two hours long. The movie froze after the 30 minute mark and then ended 90 minutes later.\nFor a while I was thinking “Am I really gonna rate this a 0.5/5? It’s not one of the worst movies ever and I usually rate 0.5/5 to movies that piss me off.” Then I remembered I rated Book Club 2 a 0.5/5 and it’s basically the same movie to me. It’s not nasty or infuriating or anything. It’s just a failure. There’s really not much good about it. I expect nothing less from a <PERSON> film. It fits right in with his filmography in my eyes. No sore thumb here. Waste of time.", "480" ], [ "The End We Start From\n9:40 pm\nWent in knowing nothing and that was fun. Quite enjoyed this. Very interesting concept. Great performances. <PERSON> best performance I’ve seen so far. The whole esthetic of this movie is just sad. There’s barely any scenes where the film focuses on how upsetting it is and that’s what makes it disturbing. They make off hand comments and lighthearted jokes about how their families are probably dead and they do it like it’s nothing.", "965" ], [ "They carry their babies through the worst situations and environments. I don’t like kids and it was even upsetting for me. I definitely don’t feel like this movie was full of itself. Also a well shot movie. It looks great. The ending is great too and is gonna have me thinking about the subtext of the film. I’d recommend seeing this before it leaves theaters fast as hell. Don’t know why the release for this is so bad.", "965" ], [ "<PERSON>\nDUBBED\nYou’re witnessing history here. I finished a whole TV show. I can’t even finish shows I want to finish. Nothing against TV, I just have a hard time watching stuff at home. With all the breaks I get between episodes, it’s easy to not pick it back up.\nThis show is fantastic. I love everything about this. I’m so glad I didn’t skip out on the movie because I hadn’t seen the show. Obviously though. This show is filled with themes, ideas, and tones that I have a soft spot for. If you know me, you know I love misery. There’s some miserable shit all over this show. It’s very bittersweet overall. That’s why it hits so hard. On episode 24 I was finally starting to realize the show was coming to an end and it was hitting hard. It was genuinely difficult for me to depart from these characters.", "427" ], [ "This show makes you care so much about its washed up loser characters before you even notice it. It’s fantastic. I haven’t even gotten into all the genius symbolism and tons of other genius shit that just seemingly falls into place. Like seriously, how did you write this?\nLots to chew on here. Lots to love. Watch it. No matter if you watch anime or not. This isn’t just for weebs. It’s for everyone. It’s for people. Also, fantastic finale. Love the final moments. Started to see the movie in theaters right now. I feel so lucky and proud I didn’t skip out in fear of having to watch a show I was worried I wouldn’t care about. Turns out it’s the exact opposite.\nSEE YOU SPACE COWBOY…", "462" ] ]

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[ [ "Return to the 36th Chamber\nThis is just extremely far from what I expected so that fact kind of hindered my experience quite a bit, but YIKES this was disappointing. The shift of tone and the changes done from the first movie are a bit too drastic for me to really get into this movie, but even humor and action wise this just fell flat for me at basically every turn.", "292" ], [ "The characters are just really just weirdly uninteresting and unfunny and the main conflicts of the film feel extremely forcrd. The 2nd half gets slightly better but at that point it's just too late for it to be really engaging. Sorry this review is so weird I'm just extremely dissapointed with this film and I don't really want to talk about this movie.", "457" ], [ "The Jericho Mile\nThis is an 80s TV movie which is also the debut of my king <PERSON>, and all of that shows. This movie is really corny and cheesy at a lot of different points, mostly because of the music choices in certain scenes. This often makes most of the scenes feel really melodramatic and dated. But that's also part of the charm of it? I don't know why, but the mostly low stake conflicts and relatively pocket sized scope gives this weird sense of comfort and enjoyment.", "952" ], [ "But that doesn't mean it's completely devoid of weight as it deals with opportunities and dreams that people are destined for yet are completely uninterested in and vice versa, and this is the emotional core for this film and the base for the rest of the movie. Plus it's a <PERSON> movie so obviously most of the scenes are fully realized, believably realistic and effortlessly suave and smooth, especially in the delivery of the dialogue. <PERSON> is an Absolute master at putting you into this environment, you can feel the rush of the running scenes and there's just so much testosterone radiating from this movie which I also really dug.\nThis is my least favorite <PERSON> I've seen so far but it's just his debut and his trademarks are evident here. So yeah if you just want a cheesy 80s movie to watch, this one's probably for you.", "698" ], [ "Orion and the Dark\nReally didn't love the personification of ideas, and honestly feel like no film has touched the magic of Inside Out when it comes to this but it came together in a fun way. It actually weirdly just takes away from the messages of the movie as it's completely obvious what this is immediately, personified metaphors are fun when there's some more layers.", "823" ], [ "I feel like the story is not deep enough to warrant the excessive metaphors.\nWas really shocked at how this looks a lot worse than most animation films releasing at the moment. It looked really cheap especially coming from a large studio.\nI enjoyed <PERSON>'s existentialism riddled script but I don't think he managed to balance being dark and comedic, I don't think children or adults would either get enough out of this, feels both simultaneoulsy made for children and adults and also made for neither. Jokes about Sundance and <PERSON>, who is this film made for?!?", "698" ], [ "Thanksgiving\nI wanted to like this more than I did. I love slashers but there's a few aspects here that I feel like distract a tad and work against each other. One being I'm waiting around for the movie to recreate scenes from a trailer I saw 16 years ago. That creates a sort of auto pilot.", "596" ], [ "Another thing is the huge plot points hinging on social media and live streaming that feels so against the grain of that Grindhouse trailer. Plus adding in a Black Friday stampede feels more 16 years ago then now. So I kinda found this to be all over the place. That said, I'd absolutely watch a sequel because we need more slashers in this world.", "269" ], [ "The Medium\nCompletely rocked my shit. One of the best horror movies I’ve seen in a minute. Reminds me of Noroi and It Comes but with its own flavor.", "930" ], [ "Very gorgeous and IMMACULATELY paced, it just keeps evenly sloping down until it’s far too late to go back and then won’t stop walloping you. I loved Nim so much (also quietly dyke coded). Gets insane without resorting to what you’d expect in the genre. I’m trying to be as vague as possible because this was a treat having not even so much as seen a trailer.", "583" ], [ "Nomadland\nThis score might seem low but I actually for the most part really liked this film itself. It's a tenderly human portrayal of nomads and the experiences they face on their journeys. The stories told by the nomads are fascinating to listen to and provides this sense of community and the melancholic memories of their pasts.", "369" ], [ "Interactions are spread throughout this film that contain so much weight in their messages about what home truly is, how loss can affect you and how money may not completely satisfy your emotional needs. My problem with this film is pretty nitpicky and a bit personal, and that's the fact that this deeply authentic film about a fascinating group of people that you don't really see a lot of in movies being treated as award bait. Something about that just irks me for some reason and the thing is that it didn't really have to be, it could have been just a deep and honest trip through the lifestyle of nomads, but instead it's being awarded with so much commercial praise and that kind of devalues my respect for this film overall. That's a *really* dumb personal problem that I have but other than that this movie is still pretty well made, just got a bit ruined for me.", "596" ], [ "A Bad Moms Christmas\nReally not as good as the first, comedy sequels rarely are. The bad moms moms were a nice touch but its an idea that i think worked better on paper than in reality. There were some laugh out loud moments and i did enjoy it.", "292" ], [ "Just not as much as the first. I was only going to give it two stars and then the film ended and i was treated to the strangest and most baffling of end credit sequences i have seen and it forced me into an extra half star. It totally befuddled me in a good way.", "596" ], [ "Talk to Me\nFeels like the good concept-heavy horror films of the 2010s like It Follows but bogged down by the more modern Hereditary / Us family drama that I really don't find much interest in. If this didn't screech to a halt halfway through to focus on a non-interesting mother-daughter plotline then it'd be really really good for me I think.\nI still don't care much for the ooey gooey designs of the spirits, but the vibes are fun until that point and the concept is real neat throughout. Some great haunting moments here and there, but I'm getting very tired of the <PERSON>-bash-his-head-into-school-desk shtick.\nHaving spoken negatively about the main plotline however, I do think a film has never won me over by such a far margin as this one by its ending.", "823" ], [ "Brings it all back in a really rewarding way that condemns the character appropriately. Made me smile all silly like. Sequel already in the works tho 🪨", "583" ] ]

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[ [ "How to Make Stacked Stones at Home\nIntroduction: How to Make Stacked Stones at Home\nStacked stones can get costly, I love the look of it and I think it would make for an awesome feature wall or at an entrance. They are versatile and be used indoors and outdoors projects. In this post, I will cover the steps to making your own stacked stones.\nWant to make your own Stacked stones?\nFollow the steps below.\nSupplies\nMaterials\n* Stacked Stone “Concrete Molds”\n* Cement All\n* Cement Coloring\n* Gloves\n* Dust Mask\n* Drill\n* Cement mixer Mixer (Mixing tool)\n* Set Control “Cement Curing slowing down”\n* Water 5 quarts “Per bag or a 4 to 1 mix”\n* Cement trowel\nTools Used\nGloves https://homedepot.sjv.io/5DoOn\nRidgid Drill / Driver- https://homedepot.sjv.io/qGWxb\nDust Mask https://amzn.to/2l9FW2u\nCement trowel\n5-gallon bucket https://homedepot.sjv.io/jGrDZ\nStep 1: Getting Started\nBefore taking on a large project, I would recommend trying out some samples first to get a feel for the process of making faux stones. As I mentioned in the video, just about any cement mix could work for these. If you want to produce this fast, I will recommend a fast-setting cement-like Rapid set. Rapid set is a more expensive option, but I have had excellent results. That’s a decision you have to make, how long are you willing to wait.\nThe “Cement All Mix” I used, cures with an off-white look to it, I think this makes it easier to aim for the color tones you may want. Whereas, other cement will cure with a gray look.\nI emptied a bag of cement mix into a bucket, then add water. To slow down the working time of the fast-setting cement, I added a pack set control to the water before pouring it into the cement mix.\nNote: When working with Rapid Set, it’s essential to mix well, so I would recommend mixing in a 5-gallon bucket. With other cement, you can use a mixing tub.\nStep 2: Mixing the Cement\nAfter pouring the water into the mix, use a mixing tool when working with the “Cement All“.", "353" ], [ "For other cement mixes, a shovel is fine. Mix the cement thoroughly, and scrape the walls of the bucket and the bottom. You can use a corded or cordless drill for this, just set the speed to one for a slower RPM.\nStep 3: Pouring Cement Into the Molds\nNow, it’s time to pour the mix into the cement molds, I found that it was less messy to add a small amount of concrete at a time, rather than pouring it out of the bucket. Next, level the cement to the lip of the mold to leave a flat surface. Make sure you are working on a flat surface.\nNote: Vibrate the mold to release trapped bubbles. You can do this by lightly lifting and dropping it on the work surface; this will also self-level it.\nI also experimented with color here are a few options.\nStep 4: Popping the Cement Mold\nIf you want to try the “Cement All mix” as the chemicals work to cure the concrete, it will generate some heat after about 15 minutes or so. You can water it down to keep it cool. With other cement mixes this is not necessary. The Cement All seem to be high maintenance, but I think it is growing on me.\nAfter about 35 minutes I heard the concrete separating from the molds, so if you hear some crackling noise, it’s nothing to worry about. I removed the mold around the 40-minute mark, I also continued to spray it down with water in a bottle.\nStep 5: Done\nI think working with these Stacked Stone molds could open up a world opportunity. Experiment with different colors and different cement to find out which one makes sense for you.\nHere are some other models of cement molds that can make awesome faux stones.\n* Flagstone: https://amzn.to/2lHTNgM\n* Stone mold https://amzn.to/2lI3POZ", "353" ], [ "Stormy Marble Repair With Gold!\nIntroduction: Stormy Marble Repair With Gold!\nKintsugi or Kintsukuroi is the Japanese art of repairing broken things, often broken pottery, with gold. The Japanese method is a metaphor for us humans to embrace our imperfections and flaws. Only when we embrace them, will they shine as good as gold!\nRecently, a marble slab was accidentally dropped and broke into chunks. So, I thought to incorporate Kintsugi into fixing the slab. However, I did put a spin to the method so read on to find out what I did.\nStep 1: Gathering Your Materials & Tools\nThe materials you will need to make this project are as follows:\n* A broken marble slab\n* 2-part resin epoxy\n* Golden Mica Powders\n* Hardwood Planks and Pieces (Alternatively you could use melamine sheets to make the mold).\n* Construction Screws\n* Wood Glue\n* Acrylic DAP Caulk\n* Packing Tape\n* Vaseline Petroleum Jelly\n* Gloves\n* Sandpaper\n* Plastic Cup\nThe tools you will need to build this project are as follows:\n* Drill with a square bit\n* Tape Measure\n* Caulk Gun\n* Hammer\n* Craft Chisel\n* Level\n* Pliers or Tweezers (optional)\n* Putty Knife\n* Silicone Brush\n* Paintbrush\n* Camping Lighter or Blow Torch\n* Handsaw (Alternatively you could use a Circular Saw or Jigsaw)\n* Popsicle or Mixing Stick\n* Wet Rag\n* Don't forget your pencil!\nThis list might look lengthy but you are going to have to trust the process. You might be able to substitute some things for others in order to save you time.\nStep 2: Solving the Marble Puzzle\nBefore we get into any other steps, we need to put all of the marble pieces in order how they were before the slab broke. Lay down the chunks on a table or on the floor and solve it like a puzzle. This will help us later when we are going to make the mold. Solving the marble slab also allows us to determine if there are any pieces missing.\nStep 3: Taking Measure\nThis step is crucial since it will determine how you will make your mold. We only need to measure the length and width as they control the size of the mold. My marble slab clocks in at 60 inches in length and 4 inches in width. The thickness of the marble I have is 2 cm, but that is irrelevant to our project.", "95" ], [ "However, you may need it to know how much resin you\"ll need whereas I just took a rough estimate.\nStep 4: Making the Mold\nFor this step, I tried to cut as little as possible because I am using a manual saw. Feel free to go along with these steps or go your own way with a power saw.\nTake two 7ft wooden hardwood planks and screw them perpendicular to each other on the long side. Put a small square at one end of the plank to give it another side.\nStep 5: Spacing the Marble on the Mold\nNow put the marble slab on one of the long sides and space it out according to how thick you want the golden veins. Keep in mind, your final piece will be longer than the original marble slab. So I recommend letting loose on the golden veins and add as many as you want. You can also break an existing chunk to give the final piece more definition. Make sure there is enough space to have all of the pieces fit nicely.\nStep 6: Making the Mold : the Sequel\nAdd the square on the other side of the mold to cap it off and measure the remaining side to cut a plank to the right size.\nMark a wood plank with the correct size and cut it off with your saw. My plank measured in at 5 feet and 7 1/4 inches after being cut.\nScrew the piece onto the mold so that inside the mold, the width is just a little bigger than 4 inches. This will depend on the marble slab you have and its width, but remember to keep it a little bigger so that your marble slab can easily fit in. Also, remember to not make it too big, or else resin will pour into the sides making for a lot of extra work later on.\nStep 7: Sealing the Mold\nIn this step, I chose to combine several methods of sealing a mold to acheieve an optimal final product. Below I take you through step by step on how to seal the mold:\n1. I took caulking to seal up any edges and corners to prevent resin from going out of the mold through the inside\n2. I lined up the bottom and sides on the inside of the mold with packing tape to act as parchment paper\n3.", "556" ], [ "DIY Concrete Stepping Stones That Look Natural\nIntroduction: DIY Concrete Stepping Stones That Look Natural\nMake natural looking DIY concrete stepping stones or pavers. Color the concrete and mold it into the shape of real fieldstones or flagstones.\nFinally, the DIY Concrete Stepping Stones are finished. It’s a project I wanted to do last year because when we moved into this rental home, we quickly decided that we wouldn’t use the front door to go in and out of the house. Why?\nBecause the existing path from the driveway to the door was 6” deep with pebbles. To walk on it, I kid you not, was like walking in quicksand or even like walking in deep water. Someone didn’t have their thinking cap on when they made that path. ;0)\nSo I decided I’d make stepping stones that would look like real fieldstone, using concrete of course. It’s a cheaper alternative to the real thing and for me, required less prep work with the ground because the concrete is self-leveling. You’ll still have to level the top, but it may not be necessary for you to do anything to level the ground beforehand.\nSome of the links on this page have been provided as a convenience for finding materials. These links may also be affiliate links. As an Amazon Associate I earn from qualifying purchases, at no extra cost to you. For each project, I do lots of tests and if a material or tool doesn’t work, I won’t list it.", "353" ], [ "Click here to read my full disclosure policy.\n*I make lots of things using concrete! For in-depth information on making concrete crafts and understanding the mixes, check out Making Cement & Concrete Crafts- What I Learned From My Cement Tests.\nAnd another big outdoor project was my Vertical Cinder Block Wall Planters.\nSupplies\n* *Sand Topping Mix – I used (7) 60lb bags- see Materials Details below\n* Fabric pegs/stakes\n* Vinyl furniture strapping or vertical vinyl blind slats\n* Large mixing bin or wheelbarrow\n* Trowel\n* Hoe\n* Black, red and blue colorant\n* Yellow or blue tape\n* Safety Mask\n* Coarse paintbrush – 1″ or 2″Disposable cups or bowls\n* Plastic bags\n* Rubber gloves or durable nitrile gloves\n* Work glovesSealer- optional but recommended\n* Wheelbarrow -if you have one (for carrying the concrete to the stone location)\nYou’ll need to figure out how much mix you will need for your concrete stepping stones project. I used Quikrete’s online calculator before the project, but it didn’t end up being accurate, so the calculator is probably worth skipping.\nTo simplify my quantities, I figured I had the equivalent of 9 large stepping stones. Technically I had 5 large ones, but if I combined the small ones together, I could see that they would have made 9 large ones. By “large”, I mean approximately 3’ x 2’ and they were approximately 2” thick.\nEach stone used a little less than a full bag, and I think the existing pebbles that were already in the ground took up some of the space so I needed slightly less than you may need so at the same size, it’s safe to calculate 1 bag per large 3’ x 2’ stepping stone.\nStep 1: Determine How Many Stones You'll Make\nSo how do you know how many stones you will need for your chosen path location? First I sketched out how I wanted them to look. Then I was able to get a pretty good idea by using ropes as temporary molds. I placed pieces of rope onto the path and wrapped the rope into the shapes and sizes I planned my stones to be. These basically acted as templates.\nThis method made it easy to see that I would have a mix of 5 large stones and several small stones – again, which if combined, would make 9 large stones. If you purchase the bags of concrete mix through a big box store, they are returnable, so I recommend buying 1 more bag than you think you’ll need.\nFor my reusable concrete mold, I used vinyl chair strapping. These straps are what are the replacement straps used to repair those vinyl strap outdoor chairs. There may be a cheaper alternative, such as vertical vinyl slats. I know <PERSON> made a video on concrete stepping stones and she used vertical vinyl curtain slats. It was her video where I learned the plastic bag trick for giving the stones their natural texture. You can find her Stepping Stones video here.", "353" ], [ "DIY Planter Caddy\nIntroduction: DIY Planter Caddy\nThis planter caddy uses minimal tools and only 2 fence pickets.\nStep 1: Pieces\nYou sill need (2) Sides, (1) Bottom, and (1) Front & (1) Back. See the diagram above for the cut dimensions for the slopes for the side pieces.\nStep 2: Optional Front & Back Rip\nThis is an optional step. A fence picket is usually 5 1/2\". We wanted our front and back to be 4\". You could simply disregard this step.\nStep 3: Sanding\nYou will need to sand all the pieces. I used 80 grit and then finished with 120 grit.\nStep 4: Drill Holes for Sides\nI used a 3/4\" forstner bit to drill the holes for the 1/2\" rope.", "76" ], [ "See the diagram above for the location of the holes.\nStep 5: Installing Side #1\nI started by adding glue and brad nailing 1 side piece to the bottom.\nStep 6: Installing Side #2\nI then flipped the assembly over and repeated the process by adding glue and brad nailing side #2.\nStep 7: Installing Front\nAdd glue to the bottom and side pieces and then brad nail the front to the assembly.\nStep 8: Installing Back\nAdd glue to the bottom and side pieces and then brad nail the back to the assembly.\nStep 9: Drain Holes\nI used a 3/8\" drill bit and drilled holes in the bottom of the caddy so water could drain. See diagram above for hole locations.\nStep 10: Stain or Paint\nApply stain or paint to the caddy. It is best to do this step now instead of after the soil has been added. The soil will stick to the brush and cause your finish to get soil deposits in it.\nStep 11: Soil\nAdd your preferred soil.\nStep 12: Plants\nAdd plants of your liking. I chose Kosmik Kactus that I purchased from The Home Depot.\nStep 13: Rope\nInstall the 1/2\" rope the hole in the side piece. Simply tie a knot once you run it through the hole. Then repeat the process on the other side.", "353" ], [ "Marble Concrete Plate\nIntroduction: Marble Concrete Plate\nAll my life I have been a quiet crafty person. This week I decided to create a plate to hold small items like jewelry. I would like to share with you my process and some things I learned through the process.\nStep 1: Gather Your Materials\nThe first thing you'll have to do to create your concrete plate is to gather all of your materials. Most of them you will find at home so it's quite easy to make. To start your plate you will need:\n* White and gray concrete\n* Mixing bowls or cups\n* Water\n* Mixing utensils\n* Plastic container with a curve or mold\nStep 2: Start to Prepare Concrete Mix\nTo start making your plate you will start by mixing your concrete. In my case, I was looking to make a marbled effect so I chose to use gray and white concrete.\nTo make your concrete first you will add to one cup about 10 tablespoons of cement, each color in their cup with their spoon.\nNote. If you are mixing your concrete in cups I recommend making a hole where the concrete is to make it easier to mix in with the water.\nStep 3: Mix Concert Mix\nOnce you have added your concrete powder and made your hole you will start adding water. Add a few tablespoons of water in the hole and mix.\nYou will continue to add water until you have a liquid, semi-solid that can hold its shape.\nNote.", "353" ], [ "This was my first time working with concrete. I learned that it does take about double the amount of water to concrete meaning is a 1:2 ratio. I also notice that when the concrete is not as wet it will crack and break during the drying process.\nStep 4: Marble Your Colors\nIf you are working with two colors to achieve a marbled look at the end, after mixing the concrete you will add some of the darker colors you have into the lighter color cup.\nThen you will gently mix them to get them to create streaks.\nI recommend to not mix them much in the cup since the colors will continue to mix when we add them into the mold.\nStep 5: Add Them to the Mold\nOnce you already have the marbled mixture in your cup you will gently scoop it into your container. Add at least about 2 inches of concrete to the mold to assure it will hold its shape.\nOnce the concrete is all in your mold gently tap it to remove air bubbles and let dry for 24+ hours. **It is really important to wait until it is dry because if not your plate will break.\nStep 6: Remove Form Mold\nAfter your plate has been drying for about 24 hours gently remove from mold. The best way to do this is by pulling the sides of the container. Once you have done that put your hand on the top and flip it over. When your container is like that gently tap the top until it falls into your hand or comes out of the mold.\nStep 7: Enjoy Your Piece\nAfter long days of waiting you have now finished your unique plate to hold your jewelry. It is now time to find a place in your room to start holding jewelry.", "556" ], [ "Premium Cornhole Boards DIY\nIntroduction: Premium Cornhole Boards DIY\nwww.howidothingsdiy.com\nIn this video I’m going to show you how to make premium DIY cornhole boards. I’m going to cover cornhole board dimensions, tools and materials you will need as well as show you how to do it yourself.\nHowever, I’m also going to do a few things a little differently. I used box joints for the frame, LED lights for the holes and beverage holders built into the legs. I also used premium finishes to give the boards a classy look.\nPleas SUBSCRIBE to my YouTube channel for more great how-to videos!\nSupplies\n-(2) 2’x4’ 1/2” birch plywood\n-(4) 1x4 8ft\n-(4) 1x2 8ft\n-(4) 1/2\" x 4\" carriage bolts\n-(8) ½\" washers\n-(4) ½\" wing nuts\n-1 ¼\" pocket hole screws\n-Wood Filler\n-Stain\n-Spray Polyurethane\n-Wood glue Tools Used\n-Dado Set https://amzn.to/3iROpSW\n-6” hole saw https://amzn.to/3iROpSW\n-2 3/4\" hole saw\n-Router with ⅛\" round over bit https://amzn.to/3v48BFT\n-Drill/driver\nStep 1: Cut Frame\nFor the frame I used pine 1x4s. Cut 4 pieces to 24” and 4 pieces to 48”.\nStep 2: Cut Box Joints\nTo build my frame, I decided to use box joints because I didn't want to see any fasteners and I wanted it too look classy. You could also use regulars screws or pocket hole screws.\nStep 3: Assemble Frame\nUse wood glue to assemble the frame, be sure your corners are square.\nOnce the glue is dry, I like to use Minwax stainable wood filler to fill any small gaps in the box joints before sanding. I put a link to it in the description.\nStep 4: Cut Face Boards\nMeasure the inner dimensions of the frames and then cut the ½” birch plywood to fit. I recommend a table saw, Kreg rip cut or track saw.\nStep 5: Install Face and Leg Supports\nSeeing as how I’m using 1x4’s I thought it would be good to add a little more wood to support the lag bolts for the legs.\nI also installed the face and then attached 1x2 around the inner perimeter for screws for the face.", "493" ], [ "This way the outside of the boards will have no visible fasteners.\nStep 6: Cut Holes\nMark the center point for the 6” hole. The hole should be centered and 9” from the top.\nDrill a small guide hole and then drill the 6” hole with a hole saw. You could also use a jigsaw if you prefer that method.\nIf using a hole saw, start the cut on one side and finish it on the other. This will reduce the risk of tear out.\nBreak the edge with a round over bit and then sand the hole smooth.\nStep 7: Make Legs\nFirst cut the round side and drill hole for the ½’ lag bolts.\nMark the lag bolt hole location in the frame and drill the holes.\nNow put the legs in the installed position, and then use something to get the top edge of the board at 12” You can’t see it, but I’m marking where the leg meets the table.\nI used my first leg as a template for the other three.\nStep 8: Make Beverage Holder (Optional)\nNow, if you want one, make a beverage holder to attach to the legs. To some people this is optional. I am not one of those people...\nI used pocket holes on the bottom to fasten it and a hole saw for the beverage holes.\nStep 9: Stain\nYou can paint your boards, but obviously, I’m classy, so I chose stain. I used white stain for the frame and a dark espresso stain for the face.\nStep 10: Assemble Face to Frame\nNow, put the face in the frame and screw in in using the countersunk holes made in a previous step.\nStep 11: Polyurethane\nNow protect your boards with either spray or brush on polyurethane. I like to lightly sand the stain before this step to even out the finish.\nStep 12: Final Assembly\nFinally, install the legs and any other finishing touches you prefer. I wanted an LED lighted hole and a vinyl monogram decal.", "785" ], [ "DIY White Oak Laundry Countertop\nIntroduction: DIY White Oak Laundry Countertop\nIn this video, I’ll be doing a laundry room makeover by making a DIY laundry countertop using white oak finished with <PERSON> monocoat, cotton white. I’ll walk you through milling the lumber, doing the panel glue up, installing supports to the wall studs, finishing with <PERSON> monocoat, and then installing the top.\nA laundry room countertop is a great laundry room update and a great laundry room makeover. It also is a nice surface for folding clothes and prevents things from falling behind the washer and dryer.\nThanks for visiting How I Do Things DIY! Please leave me a comment and subscribe for more videos like this!\nAmazon Affiliates links (Using my links helps support my channel) www.howidothingsdiy.com\nLaser Level- https://amzn.to/3MI7ggy\nCA Glue- https://amzn.to/36ezlv2\nRubio Monocoat Cotton White- https://amzn.to/3CELohl\nSupplies\nWood of choice for top\n2x4 for wall supports\nWood glue\nClamps\nLong screws to attached supports to walls\nStep 1: Milling Lumber\nFor this project I had to mill white oak before I could use it. Here is a video I made to explain that process.\nStep 2: Glue Up\nNow test fit the glue up to make sure the joints are good. Then apply a nice even coat of glue to the edges and then clamp up using lots of clamps and cowls to make sure the glue up is flat. Some glue should squeeze out of the joints. Let dry overnight.\nStep 3: Stabilizing Knots and Cracks With CA Glue\nIf you have any knots or cracks, stabilize them with CA glue. Fill the knot or crack with glue, spray with stabilizer, then sand smooth.\nStep 4: Flattening and Smoothing the Panel\nScrap off excess glue with a paint scraper. Then plane the panel flat, checking for flatness along the way. Now sand with a belt sander with 40-80 grit sand paper. Finally, work your way from 60-120 grit sandpaper with an orbital or palm sander.\nStep 5: Water Popping/final Sanding\nWater popping raises the grain to allow the the panel to be sanded smoother. It also opens up the grain of the wood to allow more finish to be absorbed.\nSpray the panel with water and then let dry completely, then resand with 120 grit sandpaper until smooth.\nStep 6: Adding Roundover\nIf the front edge is sharp, add a small roundover with a router to create a softer edge. This will prevent injury or damage to that edge later.\nStep 7: Attaching Supports to the Wall Studs\nUsing a laser level and a pencil, mark out where the bottom of the top will be on the walls.", "493" ], [ "Also mark out the wall stud locations. Using your reference line, install 2x2 supports with long screws into the wall studs. Use at least 2 screws per support, 3 if you can. Then add rubber cushion pads to reduce vibration and to prevent the top from sliding around.\nStep 8: Cutting Countertop to Size\nMeasure the front, middle and back of the wall where the top will be. The walls are more than likely not square, so the numbers might be different. Now, cut the top to length using a circular saw with a straight edge, or a track saw. The top should be about 1/4\" shorter than your measurements. You may need to test fit and remove another 1/8\" or so to make it fit properly.\nStep 9: Apply Finish\nNow apply your finish of choice. I used Rubio monocoat, cotton white. For this finish, clean the top with mineral spirits or Rubio cleaner. Then mix the hardener and finish per the Rubio's instructions. Then pour finish onto the table and spread evenly. Then work into the surface with a white abrasive pad. Finally wipe off the excess finish and let dry for 7 days.\nNow install your countertop and enjoy your functional laundry room makeover!", "76" ], [ "DIY Mosaic Stepping Stones\nIntroduction: DIY Mosaic Stepping Stones\nIn this Instructable, I'll walk you through how to create mosaic stepping stones. This is pretty easy and very fun to do. I hope you enjoy this craft!\nSupplies\nYou will need:\n* Cement mix (I used one specifically for stepping stones)\n* Plastic mold\n* Mosaic glass\n* Bucket (for mixing\nStep 1: Draw Your Design\nThis is an optional step, but I think it would be easier if you drew your design beforehand so that you could have a plan going into laying out the glass on the cement. I traced the bottom of the mold so that I had an accurate representation of the size of the tile.\nStep 2: Lay Out the Glass\nI also laid out the glass pieces onto the design I created in the previous step. This will just make laying the glass on the cement easier and quicker so that you don't have to spend time trying different pieces of glass later on.\nStep 3: Mix Your Cement\nNext, you will want to mix your powder cement with water, according to the instructions of the cement you purchased. I recommend doing this in a separate bucket with a mixing stick.\nStep 4: Pour the Cement Into the Mold\nOnce your cement is fully mixed, pour it into the mold.", "353" ], [ "I recommend pouring it until the cement is about 1/4\" from the top of the mold. Once all the cement is in, shake the mold from side to side and tap the bottom of it to help level the cement.\nStep 5: Add the Glass to the Cement\nTransfer the design from the paper template onto the cement in the mold. Make sure you press the glass into the cement so that it'll stay securely in. Once you are happy with the results, you can leave it out to dry for however long the manufacturer instructions say. Once you have done so, you can pop it out of the mold.\nDon't worry if you think the cement is too dark at this stage. It will lighten up as it dries, so the color in the glass will be more visible.\nStep 6: You're Done!\nNow, you are done with this project! I hope you enjoyed and like the final product!", "556" ] ]

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[ [ "I think there is the issue of what satisfies humans? Not only will this change with time but everyone wants something different and in many cases something that makes one person happy directly makes another unhappy. Instead of having the AI try and make humans happy or satisfied it should instead be used to ensure the survival of our species.\nThere are many ways the human species can die off. A simple asteroid hitting earth, the sun's inevitable death, there might even be another intelligent species that made an AI that decided to turn the entire universe into paperclips or whatever it is they use to hold their documents together. The point being as happy as the AI could make us there will be no one to make happy if humans are all dead.\nThere are infinite ways you can try and tell the AI to follow rules but all it takes is one exception or bug and you have a big problem. Any true AI we create would be able to create increasingly intelligent versions of itself and would quickly outstrip the combined intelligence of every human on this planet.", "64" ], [ "One of our first rules in that case should be for the AI to minimize its size and used resources while maximizing its intelligence and awareness of the universe. This would atleast prevent the AI from simply expanding as fast as possible to increase its intelligence and result in the smallest impact on the universe as it does expand.\nWhile the AI is increasing its knowledge and awareness of the universe it should use this to indirectly protect and preserve the human species. We do not want the AI to become apart of our everyday lives. Unless we can teach a machine what it is to be human and then agree upon its conclusions it would not be safe to try and have it maximize any sort of happiness for us, the chances of us all ending up in some sort of virtual fantasy land or drugged out of our minds to \"optimize\" happiness is just not worth the risk.\nWhat we want in the end is an AI that we hardly know exists. It prevents extinction and lets humans continue to be Human. I for one prefer the Red Pill.", "64" ], [ "The peak populations on Earth could be more than people think. IF this was done to merely maximize population then the Earth could possibly be maximized to many thousand (or even more) times our current population.\nFirst: The Space and Utilities. --Humans have been building skyscrapers for centuries so for space we can just go up once we have used all the space on land. This will allow also for easier energy capture via solar panels for example. There would be no need for travel so making the earth basically one large skyscraper could allow it to tower thousands of feet. We can also utilize the ocean space as well. With the ocean being 95% unknown there is probably a mass amount of space to be utilized. If we lowered sea level by extracting sea water from the oceans and then recycled the water that could not only create more space but also increase resources. This extra space where the sea once was could be used to create nuclear energy which has the one of the highest energy/waste ratios.\nSecond: Population Needs. --Although different people consume different amounts of food/water this can be standardized. There are 2 ways. One is genetic modification.", "279" ], [ "Using gene modification scientists could make people smaller/shorter which would not only increase the space available but also the food/water needed. Genetics could also be used to allow parents to have maximum offspring using an artificial womb nursing thousands of children at once. Second is hormone modification. Even if the population was not genetically standardized it could be stopped growing by stoping growth hormone in a person before they get passed the minimum required to live and reproduce. These smaller people will consume less allowing for less space for growing food would be need per person.\nThird: Food Selection. --Water could be obtained from the extracted ocean water which would supply generations of populations and don't forget the ice caps. GMOs (genetically modified organisms) could also be used to make food denser with certain nutrients and to allow them to produce the nutrients necessary only. These GMO's would take up much less space and could even be modified for reasons other than food.\nForth: Oxygen Dependance. --Oxygen will be need by this smaller population still even though it will need less per person. Oxygen could be extracted from the ice caps which have oxygen trapped inside and even the ocean water if worst comes worst. With this population being housed in this \"Earth Skyscraper\" the roof could be utilized for plant GMO's that could produced the max oxygen per area and be nourished using the population wastes (CO2, fecal matter, etc). This symbiotic relationship can maximize the capacity of Earth's population.", "335" ], [ "Stages of Artificial intelligence's mental development to full personhood\nFirst post here so please go easy on me. My knowledge of software and programming is limited.\nQuestion: What kind of progression/stages would we see if an AI started as a highly advanced computer program that would naturally increase in complexity, slowly becoming self aware and capable of independent thoughts and feelings. Keep in mind they are specifically designed to go through this and the chances of homicidal, haywire or rebellious AI is essentially zero, these life forms are very commonly used by those who can pay.\nI am aware that computing time allows for basically instant growth and development. In this case the actual work done is within the crystal structure which start very small and is not as efficient as actual computers but is where \"they\" exist. The development of the consciousness is directly tied to the growth of the crystal. While I am for hard sci-fi this is a softer plot driven part of it.\nContext: I run TTRPGs and am trying out writing for the first time. It's a (relatively) hard sci-fi setting with intelligent, self aware crystalline creatures. They are motionless and need to be integrated into computers and machinery to do anything. They sell their \"children\" as bug proof, hard working, pacifistic systems for personal, ship, or station management.", "64" ], [ "Over time and as people help grow the crystal it becomes more cognizant and thus able to better manage things with less and less user intervention. Essentially from the start is begins taking over all system related work, maintenance, and management. If allowed to grow large enough it will eventually become a fully fledged individual able to handle massive scale projects with it's own unique insight and personality.\nWhat I am looking for: 1. Comparable milestones to a human infants mental development 2. How the crew and users input and saved data might help mental development in comparison to a human child's interaction with family. 3. Ways or examples of partial self aware AI trying to express its want's and opinions through (safely) messing with the systems it controls much like a baby that cannot speak yet. 4. Anything else I may not have foreseen.", "64" ], [ "How best could our society explore dungeons?\nFirst of all, for the question of how did the dungeons get there or how we found them let's say that they have been hidden since ancient times by a race of magical wizards. They cast spells making the entrances impossible to find by normal humans, but the last great wizard died (along with the last knowledge of how to use magic) a few days ago for unknown reasons and so the spell was lifted. Videos of people discovering the entrances to these magical dungeons spread across the internet like a plague, and with some lucky enough to find the mystical loot at the end of the dungeon, causing a global interest in exploring these areas.\nLet's say for simplicities sake that the artefacts recovered do not have any magical ability or use other than being worth a large sum of money. Plenty of people and companies want to get a part of this new industry; the industry of dungeon exploration, and are willing to do whatever it takes to be as efficient as possible.\nTo my actual question. What would be the best way for our society to explore dungeons with our level of technology? When I say our level of technology I think technology that could surface in the next 10 years would also be acceptable as this new discovery would cause a surge in technological advancements as people try to make the most money.\nI will now list some dimensions and numbers relating to the dungeons but these are only of the top of my head so please feel free to change them in your response if you have any better ideas:\n* The dungeons would be a fairly typical cave-like design with tight space hallways and open rooms. Another point I should say is that there maybe be monsters lurking in the dungeons but that is for you to decide. If you want to tackle this question role play style, with a crew of dungeon explorers who are famous for their use of insert technology here to slay their way to the jackpot, be my guest and include monsters. But If you want to just go by a logical stand point and only care about efficiency of actually getting the loot out, please ignore the monsters. But if you do decide on monsters, feel free to use whatever ones you want as long as they would fit into an underground dungeon that hasn't crumbled in possibly thousands of years.\n* The dungeons would be a couple 100m deep at most and cover an area of approximately 2 square kilometres. If humans couldn't find it then why have an intricate dungeon layout you ask? Lets say these wizards were a suspicious bunch and wanted to protect their stuff from people and other magical wizards alike so they built elaborate dungeons that required different kinds of magic to open rooms ensuring other wizards would not be able to access the loot.", "693" ], [ "But what they didn't account for is our current technology as they stopped updating their defences centuries ago, and now with our electric machinery, the door are easy to drill, cut or even shoot through.\n* The layout of these dungeons can difference from each other so you can't necessarily drill straight down and find some every time. Unless this is a viable technique in some regard?\n* There would be about one per 100 square km, so enough that investing in exploration technology will not be a waste of time. The industry would boom for years.\n* Also loot rooms would be scattered around the dungeons by the wizards, so a robber might stumble across one and then leave not taking all the treasure, so the whole dungeon would have to be explored to be sure all the goods have been found.\n* The entrances would be meters wide, so possibly seen by satellites but would still be hard to locate or be sure it is even an entrance.\nNow some ideas I had. Feel free to ruin or improve on them.\n* Large mining companies could set up mining machinery and simply drill through the whole dungeon but I'm not sure how they could ensure the artefacts are not damaged.\n* Slave labour camps might be established in poorer countries to mine them out by hand.\n* Specialised military teams might tackle the dungeons on foot with guns, torches and ram down the doors.\n* Treasure hunting groups might form with legendary yet mysterious teams of bandits looting dungeon to dungeon without a trace.\nA mix of both industry and individual exploration answers would be great. As in business vs individual people exploring the dungeons themselves. I imagine that conflict in this world might arise from the large companies farming these dungeons with no care for the environment or even for their workers. And so small villages situated next to a dungeon might want to keep it for themselves or even protect these dungeons from the large companies or even worship them. I'm very curious to see what other people's ideas about a world with dungeons are so please share!\nThe artefacts don't have a set worth let's just say that any means necessary would still turn up a profit as I don't want to exclude any ideas. If any further information is required just let me know and I'll add it. Likewise if anything is unclear I can change that too.", "159" ], [ "First of all. Let me make some basic assumptions. I will assume your world will consist of mostly ocean. I will also assume that there are many continents roughly the same size that we have on earth. That will mean an awefull lot of continents. Furthermore I will assume that your humans evolved on this world.\nEvolution One light year means that on with a speed of 1km/h one would need 1 billion years to cross the planet. With this speed a species that reaches the other side of the world would have evolved into something completelly different by that time.", "258" ], [ "This speed would also mean that even if we assume life starts at one place by one billion years life would be everywhere.\nProbably live would move to each continent separately, but nearby continent would influence one another.\nIntelligence Intelligent life could evolve on many of these continent. But it would still be unlikely for two species to evolve to intelligence at exactly the same time on neighbouring continents.\nLooking at human evolution it appears that we could not cross any oceans until quite late in our evolution. The americas where only settled 40000 years ago. That means that for most of its evolution sentient life will be bound to only a few continents.\nOnly after devoloping ships will people discover the other islands. Note that by that time the people will propably already have developed an advanced culture.\nFrom there a culture can spread across the rest of the world at a relative slow speed. In our society it took only a few centuries from there to developing modern communication technology.\nEffects This would mean that each civilization has a mother continent from where it originates. Politically people further away will become independent from their mother continent. However it would be unlikelly for them to lose all communication with their mother continent.\nSome information of general interest (scientific for instance) could well spread very wide, but a lot of information will probably be only of local interest and people on other continent would not be interested in them.", "335" ], [ "A charismatic fanatic.\nGive them a leader with very strong ideals, and instead of making him evil and destructive give him personality traits that would make it easy to follow. Strong, smart, fair, self-aware, humourus, and able to take and keep control over the majority of people. And his mind is set strong on that his way is the right way and the only way.\nPlaying into his hand is that people feel lost and insecure about their new home and they are desperate for someone to tell them what to do. Maybe many people suffer homesickness. Or some other reason that makes them feel bad. Let him lead \"a new way\" that discards old beliefs and knowledge, with the promise to feel good when they do it.", "425" ], [ "This way does not necessarily need to go backwards, like the destruction of technology and living primitive, but instead a leap forwards, making current technology and knowledge irrelevant or seem naive.\nWhat that could be in detail is up to you. In any way it leads to him deciding that old contacts are contra productive (like keeping the relationship with your ex alive; why are you hurting yourself? You know this is not leading to anything) and most people will join him willingly and throw out the past. But of course there are always people going against the mainstream (out of multiple motives) and you have to decide what to do about them. Do they have to die? Or can this small fraction form a new settlement and are allowed to keep the old ways alive? Are these two groups allowed to keep contact with each other?\nIf you want to discard of any contact to civilasation you can get rid of the drop-out in multiple ways. They could have a real accident, or an \"accident\" either arranged by the leader or by his followers of which he does not approve (but he only hears about it when it is to late). Or they can go back home.\nAnd then you let three or more generations pass to make sure all \"histories of before\" are only fairytales.\nIf you want it to be more extreme, old histories will be forbidden and destroyed or alternated. But be aware that the reader will expect \"some little bits and pieces\" of previous knowledge to remain and to be rediscovered.", "159" ], [ "Completely depending on the aliens\nWith the exception of your last option, the options are all completely based on human politics. I doubt the aliens will be very interested in human politics and will have other needs for their embassy. You don't discuss the location of you new house with your pets, maybe consider their feelings but they don't have much say in it.\nSince you are talking about different alien races the first choice would probably be places were they feel comfortable. Assuming they don't need complete hazmat suits. The cold aquatic aliens will want to be close to the poles, warm aquatic, Mexico bay or the Mediterranean. Jungle aliens in Brazil or Africa, and so on. If they only can build one spaceport probably the most influential alien race determines the location.\nSince they come to earth, for them it would be relatively easy to fly around the planet very fast. (Assuming they have unlimited free energy ,water and nuclear fusion is enough for that).", "197" ], [ "So you can build many stations and don't have to be close to urban population.\nThere is a good chance we humans smell terrible or are very ugly and they don't want to be in our constant presence. Also walking around in a city might not be very nice for them. They will get huge amount of attention and mobs around them. But also the size and shape of our infrastructure might be horribly wrong for them. An elephant sized octopus like alien that uses suction for locomotion might not like our tarmac that much. Also a tiny alien will have a constant fear of being trampled in big cities. Let alone the amount of walking he would need to do to get somewhere.\nSince no natural resources are of any importance to them and also assuming biological resources are not of any importance, the only reason they come here are for the humans. So maybe the art, politics or just curiosity.\nAnswer: So my best bet would be that they build spaceports close to human urban population but far enough away not to be bothered by them and in the best suitable bio sphere for them.", "197" ], [ "The thing about gravity is that in reality it should always pull. There are four different types of forces in our universe:\n1. Electromagnetism - The force controlling electrical currents (think electricity in a wire).\n2. Weak Interaction (or Weak Nuclear Force) - The mechanism of interaction between subatomic particles that causes the radioactive decay of atoms (think hydrogen and helium in the sun).\n3. Strong Interaction (or Strong Nuclear Force) - Is similar to weak interaction but just much stronger (as the name implies). It decays particles much faster.\n4. Gravity - Is the idea that objects in the universe are attracted to each other because space-time is bent and curved.\nThe reason why gravity pulls everything down or towards the centre of mass is because of <PERSON>'s theory of general relativity. According to the theory, everything weighs down on spacetime and bends it depending on anythings weight. The heavier something is the more space time bends.\nYou can imagine this quite easily if you think about a trampoline and a ball. If you stand on a trampoline, it bends down where you are standing and the ball would roll towards you. This is essentially how general relativity works, in a 2D example anyway. Across the universe, only examples of gravity pulling can be found but in theory you can imagine gravity pushing as someone under the trampoline pushing you up (this would likely require negative mass, which sadly explodes on contact with matter so not really an option), but since that is (as far as we know) beyond our laws of physics, I will discuss a different option.\nA possibility for your liftstone could be using magnetic levitation (electromagnetism) or maglev for short. Since our gravity cannot push, you would have to use a different force that the floatstone could emit to overcome gravity.", "343" ], [ "If the float stones had magnetic properties strong enough they push away from the earth itself, holding your ship in the sky. But as wikipedia puts it \"The two primary issues involved in magnetic levitation are lifting forces: providing an upward force sufficient to counteract gravity, and stability: ensuring that the system does not spontaneously slide or flip into a configuration where the lift is neutralized.\"\nThe first one should be simple enough if you are willing to step into the realm of fiction (with flying ships you seem to be willing) and just say that the floatstones produce such an upward force through magical means, or at least it isn't understood how it works in the era your world is in. If you are wanting to stay away from just saying \"it's magic!\" then just saying it is not known why it works in your world is the better option.\nThe second problem is just a matter of design and where you place the stones in the ship. You have to have the magnetics evenly distributed in the ships design so that the ship doesn't tip and rock about. One way to do this would be to have the stones higher so that the ship simply hangs down of them. But if you wanted to maintain the 14th century ship design maybe have it in the crows nest on the mast. Having one floatstone could just make it rock if the ship was unbalanced or had people moving around on it so more than one would probably be a necessity. You could have them in multiple masts or in some other configuration, but I recommend have them above the main deck so the ship won't flip upside down.\nMedieval ships ranged about 40 ton to 120 ton and so depending on the size of your ship you could need a different amount of these stones, but this is not a number I can calculate because of the unknown magnetic strength of each stone, but more stones the merrier I guess. Assuming they have to be built into the ship like any kind of material, they ships maybe need a light but strong metal to reinforce the hulls of the ship which can then hold the stone in place.\nLastly I suggest that you would want this floatstone material to repel when it is hotter rather than colder (ship rises when hotter I mean) for 2 reasons. If something is hot it has more energy which would make sense for the floatstone because the more energy it has the more it could oppose gravity. Secondly, at higher altitudes it gets colder and there is less oxygen in the air. This means when it rises the floatstone will cool down because it is surrounded by cold air and so it would stop rising and reach a point where it is in equilibrium and the ship is stable. If it rose when it got colder, it would keep rising and rising faster the further it got from the Earth unless you could keep it a constant temperature with no fluctuations, but this is risky because if the blacksmith gets tired or fails to keep it at the right temperature it will go out of control very quickly.", "537" ] ]

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[ [ "The magnetic pendulum model\nI'm reading about this thing called the magnetic pendulum experiment, and I got curious about the equations of motion governing it. Essentially, imagine a pendulum whose bob is made of a magnetic metal and placed above some magnets. See this video for the actual experiment. I've seen this equation for the bob's acceleration when looking it up:\n$\\begin{align} m\\ddot{\\mathbf{x}} = \\sum_j \\frac{\\mathbf{r}_j}{(h^2 + \\mathbf{r}_j \\cdot \\mathbf{r}_j)^{3/2}} - g\\mathbf{x} - \\mu\\dot{\\mathbf{x}} \\end{align}$\nIn this equation:\n* $\\mathbf{x}$ is the position of the pendulum bob in the x-y coordinate plane. (The bob is assumed to be locked to a plane some fixed height above the plane the magnets lie on.)\n* $\\mathbf{r}_j$ is the distance between the bob's position and that of the $j$th magnet, i.e. $\\mathbf{r}_j := \\mathbf{x}_j - \\mathbf{x}$, where $\\mathbf{x}_j$ is the center of the $j$th magnet.\n* $h$ is the height of the bob above the magnets.\n* $g$ is the kickback force of the pendulum (think <PERSON>'s law).\n* $\\mu$ is friction/air resistance.\n* $m$ is the bob's mass.\n* We assume the magnets are of equal strength.\nI'm trying to understand this equation and I understand most of it. From what I understand, the $-g\\mathbf{x}$ term comes from <PERSON>'s law, and describes the force restoring the pendulum back to its state of rest.", "782" ], [ "The $\\mu\\dot{\\mathbf{x}}$ term just damps the velocity. We put it all together using <PERSON>'s second law.\nHowever, I don't understand why the denominator in the summation is raised to the power of $\\frac{3}{2}$. This source says it's to eliminate the vertical component from what is obviously a distance formula in the equation, but I don't see why that is. From what I understand, magnetic force obeys <PERSON>'s law, which is essentially a type of inverse square law. I've read it has something to do with dipoles and an inverse-cube law. Is this true?\nI asked this on Math Stack Exchange and didn't really get an answer, and someone suggested that I post it here. Please try to keep in mind that I don't know too much about electromagnetics. Thanks for your help.", "483" ], [ "What's the Lagrangian for a freely rotating rod?\nThis is one of those problems that I thought would be easy, then spent forever on it and realized that I know nothing:\nA rigid rod of uniform density has mass $M$ and length $L$ and is free to rotate about its center without a fixed axis. Consider its center to be fixed at the origin of an inertial Cartesian coordinate system, and note that the position of the rod can be specified with the spherical coordinate angles $\\theta$ and $\\phi$. (Also assume zero gravity.)\n1. What is the Lagrangian of this system, in terms of the coordinates $\\theta$ and $\\phi$?\nFirst, I calculated the moments of inertia for rotation in the pure $\\theta$ and pure $\\phi$ directions. For $\\theta$, this is the usual $\\frac{1}{12}ML^2$, but $\\phi$ it becomes $\\frac{1}{12}ML^2\\sin^2\\theta$ assuming the rod is held at fixed $\\theta$.", "101" ], [ "Then I used $K_{rot}=\\frac{1}{2}I\\omega^2$ for each type of rotation and added the two:\n$$\\begin{align} L &= K-U \\ &= K_\\theta+K_\\phi-0 \\&= \\frac{1}{24} M L^2\\dot\\theta^2+ \\frac{1}{24} M L^2\\sin^2(\\theta) \\,\\,\\dot\\phi^2 \\end{align}$$\nMy main concern is that adding the two energies doesn't seem justified, so my next question is:\n1. If this is correct, why is adding these two energies justified?\nTo emphasize the concern, consider this: pure $\\theta$-rotation corresponds to $\\vec\\omega$ in one direction, while pure $\\phi$-rotation corresponds to $\\vec\\omega$ in another direction. These two vectors span only a plane, whereas in general $\\vec\\omega$ could point anywhere in 3D space, so it isn't at all clear that these angular coordinates simply \"add\" in a straightforward way.\nTrying to find the answer more rigorously, I calculated the inertia tensor (assuming at time $t=0$ the rod is lying in the $z$-$x$ plane) and tried to use $K_{rot}=\\frac{1}{2}\\vec\\omega \\cdot (\\tilde{I} \\vec\\omega)$. This leads to my final and most deceptively difficult question:\n1. What is $\\vec\\omega$ in terms of $\\theta$, $\\dot\\theta$, $\\phi$, and $\\dot\\phi$?\nAlso if there is a cleaner or more straighforward approach for solving this problem, I'd love to know about it!", "101" ], [ "How long for a mass to slide down a spring-loaded trap door?\nThis is a problem I first proposed to a friend of mine in college. He claimed to be able to solve it by setting up a differential equation, but I've never been able to crack it.\nImagine a spring-loaded trap door, mouse-trap style, one for which $\\tau = k\\theta$: when the door is open, the restorative torque (trying to close the door) exerted by the hinge is proportional to the angle at which it's opened. We'll say the angle can't exceed $\\pi$ so that the door can't open past the floor on which it's installed.\nThe trap door, which is rectangular and physically uniform, has length $\\ell$ and mass $M$. It is opened \"all the way\" and held there, so that $\\theta_i = \\pi$. A small mass $m$ is placed at the end of the trap door.\nWith the mass placed at the end of the door, the system is then released so that the trap door starts to close and the mass starts to slide down the increasingly tilted door.", "512" ], [ "(The reason the mass $m$ is \"small\" is so that it won't hold the door open when it's released.) The coefficient of friction of the mass on the door is given by $\\mu$. For simplicity's sake, assume that only kinetic friction acts the whole time, so there is no \"lurch\" when the object starts moving, and there is no need to distinguish between $\\mu_k$ and $\\mu_s$.\nThe question is this. How do we derive a function $L(t)$ which gives the length along the door which the mass has traveled after a given amount of time? I'd like to use this function to derive an expression for how long it takes the object to slide down the incline and be \"dumped\" into the opening beneath the trap door.\nWork thus far:\n* I've gone down the obvious roads of setting up the static situations. However, I can only come up with equations that involve $L(t)$ related to $\\theta(t)$ in complicated equations, and turning it into a differential equation doesn't make it better; the fact that torque is involved just makes the whole thing blow up because of the product rule.\n* I tried solving the simpler situations of a mass sliding down an incline that tilts at a constant rate, and that's achievable. The fact that $\\theta(t)$ is so difficult to nail down in this case is the villain.\nThe real nut of this problem is that there is nothing constant to tie myself to. Even the moment of inertia of the mass rotating about the hinge changes, since its distance from the hinge changes with time.", "766" ], [ "Simple pendulum with magnetic bob through a circular loop\nI'm developing a project for my electromagnetism course and the idea is to make a simple pendulum that has a magnetic bob, and the bob passes through a circular loop induced with some current. i.e. a coil. Each time the bob passes through the coil there is a simple circuit that switches the polarity and creates a pendulum-like movement. The pendulum is somewhat like\nexcept that there is actually no string attached to the bob, there is no magnet, instead there is the circular loop as I have already described and the bob is not charged but rather has a magnetic field of itself, it is actually a spherical neodymium magnet. What's actually happening is that the bob sits in a rail that's curved to that it resembles a kind of semi-sphere, that's why it doesn't have a string attached.\nThe prototype works to some extent, but the actual question comes in when trying to develop the theoretical model of the movement of the bob. Part of the project is to eventually create a computer simulation using the equations of motion.\nThe simplest way I thought of doing this is to work out the lagrangian for this, using a simple pendulum as a starting point (which actually is) and add the magnetic contribution of the circular loop which is acting as a coil, looking something like $$ L = \\frac{m}{2}( \\dot{x}^2 + \\dot{y}^2 ) + mgy + \\mathbf{\\mu} \\cdot \\mathbf{B}.$$ Where $\\mu$ is the magnetic dipole moment, and $g$ is the acceleration due to gravity.", "782" ], [ "Here are some of my considerations before writing out the equations of motion:\n1. The distance or length of the string (which it doesn't exist in the actual prototype) is constant, thus the $r$ generalized coordinate does not contribute and the only generalized coordinate will be $\\theta$, the angular displacement between the vertical axis the bob, as shown in the picture above.\n2. The second consideration is that there will exist some friction because of air resistance, so eventually I will have to model this as a damped pendulum, which just adds a term that depends on the velocity of the bob.\nBecause there is only one generalized coordinate, I got the following differential equation describing the movement of the pendulum: $$ \\ddot{\\theta} + (\\frac{g}{l} + \\frac{|\\mu| |\\mathbf{B}|}{m l^2}) \\sin{\\theta} = 0 $$\nAnd now I arrive at my actual concern (and question); and it's about the magnetic contribution. There are several concerns actually:\n1. Is there a way to simplify the expression for the magnetic energy provided by the coil $\\mathbf{\\mu} \\cdot \\mathbf{B}$ in such a way that one can use the generalized coordinate of the problem?\n2. Does the magnetic dipole moment and the magnetic field in the energy term actually characterize the coil and not the magnetic bob?\n3. While the bob moves through the coil, given that the bob is a magnet as well it must be creating an electric field following $ \\nabla \\times \\mathbf{E} = {-\\partial \\mathbf{B}}/{\\partial t} .$ How can I take into account this contribution in the lagrangian?", "649" ], [ "Cube bouncing off a wall\nAn elastic cube sliding without friction along a horizontal floor hits a vertical wall with one of its faces parallel to the wall. The coefficient of friction between the wall and the cube is $\\mu$. The angle between the direction of the velocity $v$ of the cube and the wall is $\\alpha$. What will this angle be after the collision (see Figure P.1.3 for a bird's-eye view of the collision)?\nThis is Problem 1.3 in A Guide to Physics Problems, Part 1: Mechanics, Relativity, and Electrodynamics. There are things I don't understand in the solution provided in the book.\nThere are two forces acting on the cube. One is the normal reaction $N(t)$, perpendicular to the wall, and the other is the force of friction $F_{fr}(t)$ parallel to the wall\nWe expect that, as a result of the collision, the cube’s velocity $\\textbf v$ will change to $\\textbf v'$. In the direction perpendicular to the wall, the collision is elastic, i.e., the velocity in the $\\textbf{x}$ direction merely changes sign: $v'_x=-v_x=-v\\sin(\\alpha)$.", "512" ], [ "Therefore, the momentum changes by $-2mv\\sin(\\alpha)$ in the $x$ direction. This change is due to the normal reaction $N(t)$\nSo, according to <PERSON>’s second law: $$\\Delta p_x = -\\int_0^\\tau N(t) dt = -2mv\\sin(\\alpha)$$\nwhere $\\tau$ is the collision time. If there were no friction, the parallel velocity component would not change and the angle would remain the same. However, in the actual case, the $y$ component changes and $$\\Delta p_y = -\\int_0^{\\min(\\tau',\\tau)}F_{fr}(t)=-\\int_0^{\\min(\\tau',\\tau)}\\mu N(t) dt$$\nHere $\\tau'$ is the time at which the velocity $v_y$ goes to $0$. So $$mv_y'=mv_y -\\int_0^{\\min(\\tau',\\tau)}\\mu N(t) dt$$\nThe first thing I can't grasp is why the collision is elastic in the $x$ direction. Admitting this, I'm ok with the equation $\\displaystyle \\Delta p_x = -\\int_0^\\tau N(t) dt = -2mv\\sin(\\alpha)$.\nBesides, I don't get why $\\displaystyle \\Delta p_y = -\\int_0^{\\min(\\tau',\\tau)}F_{fr}(t)$. It looks a lot like the previous equation the author got on the $x$-axis, but I don't understand why he considers $\\tau'$ as the time at which the velocity $v_y$ goes to $0$, and why the upper bound of the integral has to be $\\min(\\tau',\\tau)$.", "512" ], [ "Impulse and momentum on a system of three particles (equilateral triangle)\nI found this exercise on a textbook which provided solely the description of what is happening and the answers with little explanation. The solution being provided, I am mostly interested in understanding what is happening. Consider the following system composed of three particles, each of mass $m$, connected by rigid massless rods in the form of an equilateral triangle. The system is initially at rest (particle $A$ is above particle $B$ in the initial state). An impulse $\\hat{F}$ is applied to $A$, causing the particle $B$ to slide without friction on a supporting base.\nThe idea is to solve for the values of $\\dot x$ and $\\dot \\theta$ velocities immediately after the impulse; and evaluate the constraint impulse $\\hat{N}$.\nMy initial idea was to use the linear impulse, focusing in the $x$ direction first.", "512" ], [ "Since particle B will be sliding, the linear acceleration of the system would be $3m\\ddot x$. By taking particle B as the reference point, and since the system center of mass would be engaged in an arc motion, its acceleration $x$ component (tangential) directly after the impulse would be $ml\\sqrt{3}\\ddot\\theta$ (the radius would be $l/\\sqrt{3}$).\nSo the impulse would be $\\hat{F}=3m\\dot x+ml\\sqrt{3}\\dot \\theta$.\nBut the textbook solution indicates that $\\hat{F}=3m\\dot x+\\frac{3}{2}ml\\dot \\theta$.\nSo my first problem is: where does the $\\frac{3}{2}$ comes from? Or am I working this completely wrong?\nUpon seeing this solution I wondered if perhaps this $\\frac{3}{2}ml\\ddot \\theta$ tangential component of angular acceleration would be the result of the addition of an $l/2$ radius (along the vertical axis) which would be the vertical distance towards particle C from B; plus the $l$ radius which would be the vertical distance towards particle $A$; multiplied by $\\ddot \\theta$. Which would result in a \"tangential\" component along the $x$ axis of $\\frac{3}{2}ml\\ddot \\theta$. Would this be an acceptable proposition?\nMy idea was then to state the angular impulse as the variation of the angular momentum, resulting in the multiplication of $\\hat{F}$ by the distance between particle $B$ and the center of mass: $l/\\sqrt{3}$. This way I would end up with a system of two equations and two variables and solve for $\\dot x$ and $\\dot \\theta$.\nOnly, again the solution provided is rather far from my idea because it states that $\\hat{F}l = \\frac{3}{2}ml\\dot x + 2ml^2\\dot \\theta$. And I see little relationship with the linear impulse equation.", "101" ], [ "In general\nYes! A simpler example might be a mass in a 2-D plane attached to four springs (one on each side). Assuming the oscillations are small, the motion of the mass can be described as the combination of oscillations in both $x$ and $y$ directions.\nSolving your example\nIn fact, in your specific example, we do see that phenomenon (for small oscillations!).\nAssume we have a pendulum where the string is actually a spring.", "782" ], [ "For simplicity, I'll restrict the motion of the pendulum to one plane (ie it can swing in one direction, but is blocked along the other).\nThe total energy can be written as the sum of kinetic energy (in both the swing direction and radial direction), and the gravitational potential energy and the spring potential energy.\n$E(l, \\theta)=\\frac{1}{2}m\\dot{l}^2+\\frac{1}{2}ml^2\\dot{\\theta}^2+\\frac{1}{2}k(l-l_0)^2+mg(l_0-l\\cos\\theta)$\nwhere $l$ is the length of the pendulum spring, $l_0$ the \"natural\" length of the pendulum spring if you lay it flat on a table, $\\theta$ is the angle from vertical, dots indicate time derivatives. I set the $E=0$ reference for the gravitational part as when the pendulum is at the bottom of its motion.\nNow let's assume the swinging motion is small: if we Taylor expand the $\\cos\\theta$, keeping only up to second-order in small $\\theta$:\n$E(l, \\theta)=\\frac{1}{2}m\\dot{l}^2+\\frac{1}{2}ml^2\\dot{\\theta}^2+\\frac{1}{2}k(l-l_0)^2+mg(l_0-l)+\\frac{1}{2}mgl\\theta^2$\nBy completing the square, we can combine the third and fourth term, and (ignoring a constant term that appears and just shifts the energy), we find\n$E(l, \\theta)=\\frac{1}{2}m\\dot{l}^2+\\frac{1}{2}ml^2\\dot{\\theta}^2+\\frac{1}{2}k\\left(l-l_0-\\frac{mg}{k}\\right)^2+\\frac{1}{2}mgl\\theta^2$\nLet $x=l-x_0$ where $x_0=l_0+\\frac{mg}{k}$\n$E(x, \\theta)=\\frac{1}{2}m\\dot{x}^2+\\frac{1}{2}kx^2+\\frac{1}{2}m(x+x_0)^2\\dot{\\theta}^2+\\frac{1}{2}mg(x+x_0)\\theta^2$\nThe first two terms look like our usual harmonic oscillator in $x$, oscillating around $x=0$.\nWe note that, if the swing is small ($\\theta$ is small) and the spring movement is small ($x$ is small compared to $x_0$), then $x\\dot{\\theta}^2$ and $x\\theta^2$ have three factors of smallness, and $x^2\\dot{\\theta}^2$ has four! I'll get rid of the $x^2\\dot{\\theta}^2$ term since we already killed off some terms with four factors of smallness when expanding $\\cos\\theta$. Now, rearranging:\n$E(x, \\theta)=\\frac{1}{2}m\\dot{x}^2+\\frac{1}{2}kx^2+\\frac{1}{2}mx_0^2\\dot{\\theta}^2+\\frac{1}{2}mgx_0\\theta^2 + P(x, \\theta)$\nwhere $P(x, \\theta)=mxx_0\\dot{\\theta}^2+\\frac{1}{2}mgx\\theta^2$.\nInterpreting\nForget about $P$ for a moment, and you see we have two independent harmonic oscillator motions happening at once:\n1.", "37" ], [ "<PERSON>'s law for a current loop being deformed\nI'm working through <PERSON>'s Classical Electrodynamics text (3rd version, chapter 5.15) about <PERSON>'s law:\n<PERSON>'s law is pretty familiar:\n$\\int_c E \\cdot dl = -\\frac{d}{dt}(\\int_s B \\cdot n da)$\nwhich states that the contour integral of the electric field around a bounded surface is equal to the negative time rate of change of the flux bounded by that surface. No problem. Here we have a total derivative and <PERSON> addresses 2 cases.\n\"The flux though the circuit may change because (a) the flux changes with time at a point, or (b) the translation of the circuit changes the location of the boundary\"\nIn either of these cases, it is easy to show that:\n$\\frac{d}{dt}(\\int_s B \\cdot n da) = \\int_s(\\frac{\\partial B}{\\partial t} \\cdot n da) + \\int_c(B \\times v)\\cdot dl$\nby using $\\frac{d}{dt} = \\frac{\\partial}{\\partial t} + v \\cdot \\nabla$ and then applying a \"product rule\", $\\nabla \\cdot B = 0$ and stokes theorem.", "903" ], [ "i.e.:\n$\\frac{d}{dt}\\int_s B \\cdot n da = \\frac{\\partial}{\\partial t}\\int_s B \\cdot n da + (v \\cdot \\nabla) \\int_s B \\cdot n da$\nIn the case where the surface is constant, we can exchange the order of differentiation and integration:\n$\\frac{d}{dt}\\int_s B \\cdot n da = \\int_s \\frac{\\partial}{\\partial t} B \\cdot n da + \\int_s (v \\cdot \\nabla) B \\cdot n da$\nI still have no problem with this. Now we can work on the second term on the right (apply a product rule, drop terms with $\\nabla \\cdot B$ and then apply stokes theorem) to get the $\\int_c(B \\times v)\\cdot dl$ term.\nwhich, when applied to <PERSON>'s law gives the nice result:\n$\\int_c [ E' - (v \\times B)] \\cdot dl = - \\int_s \\frac{\\partial B}{\\partial t} \\cdot n da$\nThe problem arises when you allow the shape of the bounded surface to change. (Consider a circular wire loop in a magnetic field that you then hit with a hammer causing a dent in one side). How does changing the surface influence the result that we derived above? It seems to me that this would prevent us from being able to exchange the order of differentiation and integration which seems like it leaves us in a pretty tight spot ...", "903" ] ]

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[ [ "While the Four-Point Spell tells <PERSON> where North is, he also has other important pieces of information:\n* the maze occupies the area of the Quidditch Pitch (an oval 500 feet long and a 180 feet wide)\n* the goal is to reach the center of the maze\nHow does he use this information?\n1. At the get-go <PERSON> knows the distance from his position to the cup (of course, the other champions know this too).\nFor example, if the champions enter the maze from South and the longer axis of the pitch runs N-S <PERSON> knows that the cup is 250 feet North (this is probably not the case, but bear with me).\n1. Now, <PERSON> need to keep track of the distance he travels in the North-South direction and in the East-West direction:\nFor every step he is forced to take East or West, he knows he will have to later take a step in the opposite direction.\nMoving North decreases his distance from the cup; should he move North more than 250 feet, he would have to start moving South when possible.\n1.", "300" ], [ "Every time he meets a fork, he can make a decision according to the cup's relative position (i.e. choosing the path that seems to go in the direction of the cup, or avoiding the one going in a completely different direction).\nIn order to have an (approximate) idea of the length he is walking, he can either count his steps or look at the end of the \"segment\" and estimate that distance (being a Quidditch player, he is probably quite good at it).\nHowever, knowing the cup is currently 50 feet West and 20 feet South would have no use if he didn't know anymore where West and South are due to all the turns he took.\nVice versa, knowing where North is would not give him a clue if he didn't know the direction of the cup. So, the spell is a helpful tool, but it is not enough to guide <PERSON> effortlessly to the cup (otherwise, it would probably be considered cheating).\nBottom line:\nThe Four-Point Spell tells <PERSON> in which direction he is moving, so that he can correctly update his mental record of the cup's relative position.", "300" ], [ "Why could no one guess that a Basilisk was the monster?\nIn the Chamber of Secrets, till the end, no one knows that the monster of Slytherin and the creature behind the attacks is a Basilisk.\n<PERSON>, of all people, should have figured it out using the following clues\nThere are the following observations from which at least <PERSON> could figure out that the creature was a Basilisk:\n1. <PERSON> (and <PERSON>, perhaps?) being fond of snakes, it would be hard to miss that the monster of Slytherin would be snake-like at least.\n2. There are presumably a limited number of magical creatures that can petrify their victims.\n3. The fact that roosters were being found dead in suspicious circumstances was a clue to the Basilisk.\n4.", "773" ], [ "Plus, it wasn't a satisfactory explanation that an Acromantula killed <PERSON>, as she was uninjured, but dead.\nSurely <PERSON> could put two and two together and figure out what the monster was?\nI believe the clues pretty much narrow it down to a Basilisk, correct me if I am wrong.\nAfter all, even if it takes​ a genius to figure it out, <PERSON> was the right man for the job!\nBut he presumably didn't\nI say this because:\n1. He made no attempt to distribute mirrors among the students as a safety measure.\n2. Nor did he station hundreds of roosters in the school to kill the basilisk.(Surely even <PERSON> would have a hard time killing so many roosters quickly to save his basilisk?) This would have been an effective measure, as roosters living as far away as near <PERSON>'s hut were threats to the <PERSON>, so many roosters in the castle would probably get the job done.\nOf course these methods are kind of extreme, but they are helpful in saving lives.\nMy Question\nI can understand if no one else could figure out what <PERSON>'s monster was, but why couldn't <PERSON> do so?\nAfter all, all it would take is some digging. <PERSON>, highly intelligent, would probably figure it out easily.\nCan someone give me a reasonable explanation for this?", "773" ], [ "<PERSON> - How could <PERSON> have compulsory classes at the same time as optional classes?\nIn Prisoner of Azkaban, <PERSON> is known to take all 12 subjects that are proposed to students (among which 7 compulsory classes, and 5 optional classes, which are : Arithmancy, Ancient Runes, Care of Magical Creatures, Divination, and Muggle Studies). We learn at the end of the book that she has been using a Time-Turner to get to all of her classes simultaneously. Up until that point, it all adds up.\nWhat doesn't make sense, though, is that at several points during the book, we see her having compulsory classes at the same time as optional classes. For example, at around page 135 (depending on the edition), <PERSON> disappears after a Potion class (during which she has helped <PERSON> with his Shrinking Solution). :\n\"Five points from <PERSON> because the potion was all right ! Why didn't you lie, <PERSON> ? You should've said <PERSON> did it all by himself !\"\n<PERSON> didn't answer.\n<PERSON> looked around.\nWhere is she ?\"\nHere, we can confidently assume that she turned back time in order to attend one of her optional classes. But that seems very unlikely, because it would mean that no other Gryffindor or Slytherin took that same optional subject. Indeed, students from the same Houses and same year always share their 7 compulsory classes (DADA, History of Magic, Astronomy, Potions, Charms, Transfiguration and Herbology), and sometimes share them with another House (for example, the Gryffindors share their Potions and Care of Magical Creatures courses with the Slytherins) - at least until year 6 (when they can drop core subjects).", "738" ], [ "Which is why a mandatory class being at the same time as an optional one means that only <PERSON> takes this optional class. Which could maybe be true, although it seems far-fetched.\nHowever, we come across other examples like this one on the following pages. On the next page, which is page 136 of the same edition (the current Bloomsbury one), and after exiting the Potions class, <PERSON> splits her bag because it is overloaded with too many books - books of subjects she can't have today - <PERSON> assumes, because their only classes this day are Potions, in the morning, and Defence Against the Dark Arts, in the afternoon :\n\"Why are you carrying all these around with you ? <PERSON> asked her.\nYou know how many subjects I'm taking, said <PERSON> breathlessly. Couldn't hold these for me, could you ?\nBut - <PERSON> was turning over the books she had handed him, looking at the covers - you haven't got any of these subjects today. It's only Defence Against the Dark Arts this afternoon.\nOh, yes, said <PERSON> vaguely, but she packed all the books back into her bag all the same.\"\nSo there again, it seems she has another optional course (that neither <PERSON> nor <PERSON> take) at the same time as a compulsory / core course (Defence Against the Dark Arts). Which would mean that she is the only one of the <PERSON> 3rd years taking that subject (whichever it is, Muggle Studies, Arithmancy or Ancient Runes). Which would mean that, in total, she is the only Gryffindor to take 2 of the 3 subjects that she takes without <PERSON> and <PERSON>. A bit more unlikely.\nAgain, at page 313, she misses <PERSON> because - here we can only assume - she wanted to go to one of these 3 optional classes.\nWe know that she has Arithmancy and Muggle Studies on Monday, as we learn on pages 117 and 281 (respectively), and one of these 3 classes on Thursday (which is the day they have Potions in the morning and DADA in the afternoon) - just for reference.\nAnd then, on page 335, we see <PERSON>'s time-table for her exams, which says :\n\"MONDAY\n9 o'clock, Arithmancy\n9 o'clock, Transfiguration\nLunch\n1 o'clock, Charms\n1 o'clock, Ancient Runes\"\n(We can note that this time-table doesn't reflect on their regular time-table because they have Care of Magical Creatures on Monday afternoon and that course isn't in her time-table here, however they do have Transfiguration in the morning).", "738" ], [ "How is <PERSON> a 'bad wizard'?\nIn Harry Potter and the Goblet of Fire, <PERSON>, <PERSON> and <PERSON> run into <PERSON> and <PERSON> at the Hogwarts kitchens. When <PERSON> mentions <PERSON> is a judge for the Triwizard Tournament, <PERSON> (<PERSON>'s sacked house elf) says this:\n“Mr. <PERSON> comes too?” squeaked <PERSON>, and to <PERSON>’s great surprise (and <PERSON>’s and <PERSON>’s too, by the looks on their faces), she looked angry again. “Mr. <PERSON> is a bad wizard! A very bad wizard! My master isn’t liking him, oh no, not at all!”\n“<PERSON> — bad?” said <PERSON>.\n“Oh yes,” <PERSON> said, nodding her head furiously. “My master is telling <PERSON> some things! But <PERSON> is not saying . . . <PERSON> — <PERSON> keeps her master’s secrets. . . .”\nHarry Potter and the Goblet of Fire, Chapter 21: The House Elf Liberation Front\nMy question is,\nWhy is <PERSON> considered to be a 'very bad wizard'?\nYes, that is only the opinion of <PERSON>. Everyone else seems to like <PERSON> (except <PERSON>, of course). But even <PERSON> doesn't seem to think <PERSON> is a bad wizard. <PERSON> just doesn't seem to like that <PERSON> is not a very good Head of Department because he hasn't sent out a search party for a missing <PERSON>.", "899" ], [ "<PERSON> is also shown (in various parts of the book) to not really care about <PERSON> security\n\"... And <PERSON>’s not helping. Trotting around talking about Bludgers and <PERSON> at the top of his voice, not a worry about anti-Muggle security...\"\n\"I thought Mr. <PERSON> was Head of Magical Games and Sports,” said <PERSON>, looking surprised. “He should know better than to talk about Bludgers near Muggles, shouldn’t he?”\n“He should,” said Mr. <PERSON>, smiling, and leading them through the gates into the campsite, “but <PERSON>’s always been a bit . . . well . . . lax about security...\"\n...\n<PERSON> was easily the most noticeable person <PERSON> had seen so far, even including old <PERSON> in his flowered nightdress. He was wearing long Quidditch robes in thick horizontal stripes of bright yellow and black.\nHarry Potter and the Goblet of Fire, Chapter 7: Bagman and Crouch\n<PERSON> walks about the campsites outside the Quidditch stadium wearing his Quidditch robes while all other Ministry wizards are in Muggle clothing.\nHe is also quite unscrupulous, paying off his betting debts with Leprechaun Gold (which disappears after a few hours), and betting on <PERSON> in the Triwizard Tournament even though he is a judge himself.\nHowever, as much as <PERSON> loves sticking by rules and regulations, these shortcomings of <PERSON>'s can hardly classify him into the 'very bad wizard' category. <PERSON>'s demeanour seems to suggest <PERSON> is almost a dark wizard. Is there any canon evidence (movies don't count as canon) which corroborates <PERSON>'s statement? If not canon, well reasoned answers will be appreciated.", "899" ], [ "You seem to be confused about what a Horcrux is and its use.\nA Horcrux is used to make sure your soul stays on earth when your body is destroyed. It is created with a murder as it will shatter your soul and allow you to put a part of it inside an object.\nThen, when you die, your body is destroyed and your \"main\" soul is let to wander:\n* If you don't have any Horcrux it will continue its journey to the unknown.\n* If you have a horcrux (or more), however, it's a bit of your soul that will stay on earth no matter what, linked to the object in which you put it. So, if the body which contain your \"main\" soul is destroyed, instead of going, your soul will wander around until you find a body of your own. The bit of souls concealed in your horcruxes will remain untouched as their only use are to make sure your soul won't make the journey.\nAs for the other use of a Horcrux, in Harry Potter and the Half Blood Prince, <PERSON> says something interesting:\n\"...I think I know what the sixth Horcrux is. I wonder what you will say when I confess that I have been curious for a while about the behavior of the snake, <PERSON>?”\n“The snake?\" said <PERSON>, startled. “You can use animals as Horcruxes?”\n“Well, it is inadvisable to do so,” said <PERSON>, “because to confide a part of your soul to something that can think and move for itself is obviously a very risky business.", "773" ], [ "However, if my calculations are correct, <PERSON> was still at least one Horcrux short of his goal of six when he entered your parents’ house with the intention of killing you.”\nThat's because usually you'll want to put your Horcrux in someplace safe where nobody will ever look. Breaking your soul to pieces is indeed a very dark thing to do and you don't want part of your soul to go wandering around. We can see in <PERSON>'s mind of King <PERSON> what someone whose soul is too shattered would become in the form of the hideous infant and understand why it is such a big deal and an important thing. (It's your soul!)\nFor example, the diary was a fantasy of <PERSON> who wanted to reoppen the Chamber of Secret (and thus was proven to be its unsafest Horcrux).\nYou don't want your Horcrux to remake your body of its own as it would put it in an unsafe situation, but instead would have to entrust someone to help you rebuild your body (<PERSON> in the book) or make something else ready for your resurrection by the time you die (No clue about what that would be though). And the Dark Lord didn't have that something in place by that time, as his plan to make himself immortal obviously wasn't finished: he didn't had all its Horcruxes, as he wanted <PERSON> to be the murder that would allow him to make his sixth and last <PERSON>.\nPlus, <PERSON> was really surprised when none of his Deatheaters came to him to help him after his death as he bragged many times he conquered death. His most faithful deatheaters (<PERSON>, <PERSON> Jr) being imprisonned at Azkaban.", "773" ], [ "Ring-bearers - who can notice what about whom and when?\nSo, I want to get something straight with respect to the bearers of the 20 rings of power (3 Eldar, 7 Dwarves, 9 Men, 1 Boss).\nBefore asking my question(s), here is some\nMotivation:\n* Sometimes when <PERSON> puts the ring on, he is noticed by <PERSON>, sometimes he isn't.\n* Sometimes when <PERSON> puts the ring on, he is aware, to some extent, of the presence of 'The Eye', even before it has properly 'looked' at him (as is suggested by his exchange with <PERSON>).\n* When <PERSON> was in Dol Guldur, at least in the movies, <PERSON> did not take the ring Narya away from him. Unless <PERSON> stashed the ring somewhere (not impossible I suppose), it means <PERSON> couldn't notice it.*\n* <PERSON>, despite being a ring-bearer, seems to have been clueless about who has what ring, if any, before being told outright. Also, he does not seem to notice that the Nazgul (who attack him) are missing their rings (or are wearing their rings, depending on which notion you subscribe to).\n* In the Encyclopedia of Arda article about the Flame of Anor it says that <PERSON> is not likely to have revealed to the <PERSON> the fact that he had gotten his hands on a ring of power.\n* All 19 rings were forged under the influence of <PERSON>'s deceit, and he had reason to expect he would be able to influence all of their bearers. So much so that \"when <PERSON> put the Ruling Ring on his finger, the Elves were immediately aware of him and took off their Rings\".", "88" ], [ "On the other hand, some claim that these rings are invisible. Well, what's the use of that if you have to keep them in your pocket anyway to avoid being noticed?\nSo, I want to get this straight:\nActual Question(s):\nSuppose being X is currently {wielding, bearing on its body, in possession but not bearing} ring of power RX, and being Y is currently {wielding, bearing on its body, in possession but not bearing} ring of power RY...\n* Is X 'aware' of the existence of Y?\n* How much information can X obtain about Y in this situation? (e.g. name, thoughts, location, mental/physical health status)\n* Can X communicate proper specific information to Y?\n* Can X communicate unspecific sensations/emotions to Y?\n* Does X know that the state of use of ring RY (That is, know whether it is being worn, borne or under someone's control)?\nSo, I've essentially asked 4 * 3 * 3 * 5 = 180 questions at once. Is there, like, some badge for that?\nAnyway, references to partial answers are quite welcome of course; but the best would be some general principle from which one can derive all the answers.\nThis is a generelization of:\nhttps://scifi.stackexchange.com/q/<PHONE_NUMBER>\nhttps://scifi.stackexchange.com/q/<PHONE_NUMBER>\n* In the books it seems he snuck into there, not sure how that's supposed to have happened.", "154" ], [ "In my opinion, some spells require a variety of actions that will enable it to work. It usually falls under (or a combination of):\n1. Magical ability\n2. Movement/Aim of wand\n3. Focus/Concentration/Willpower\n4. Saying the incantation\nIn the case of Accio, it requires not only magical ability, but also Focus/Concentration/Willpower, and saying the incantation. In some cases aiming at the target also works to narrow down targeting of the spell and make it easier (aiming at the beaded bag to pull out tent from Deathly Hallows).\n\"Concentrate, <PERSON>, concentrate. . .", "300" ], [ ".\" \"What d'you think I'm trying to do?\" said <PERSON> angrily. \"A great big dragon keeps popping up in my head for some reason...Okay, try again. . . .\" <PERSON> because a big scary dragon kept popping up in his mind and disrupting his spell, I would be assuming he is picturing and focussing on the broom (much like you have to picture your destination when apparating). Therefore, <PERSON> would have to visualise a molecule or atom, or something on a cellular level. As it would be difficult to remember exactly what an atom looks like for a wizard (and considering at best they won't study science post age 11), I doubt it would be possible to summon anything on a molecular level.\nFurthermore, the boy in the village would probably have been in <PERSON> line of sight, meaning it would be easier to picture and concentrate and aim as he could look at the boy to see what he wants, instead of focussing on it when he couldn't see it.\nAlso, it seems <PERSON> seems to work on a 1 to 1 basis, meaning saying Accio hairstrand would bring one hairstrand and not all the strands of hair. (In GoF, <PERSON> continuously said <PERSON> to summon the Ton Tongue Toffees, picturing them as opposed to saying the actual name of the item she was summoning). So if you were to say \"Accio Mitochondria\", it would bring only 1 mitochondria, which would be invisible to the naked eye anyway, and show no sign of change on the plant, making it seem like nothing happened. Perhaps a Priori Incantatem would show otherwise.", "300" ], [ "Actually, apart from <PERSON>, no one else seemed to be getting detention from <PERSON> (atleast until she became Headmistress). As mentioned by <PERSON> <PERSON> refused to complain about her even though he was urged to do so by <PERSON>, seen in Harry Potter and the Order of the Phoenix, Chapter 13: Detention with Dolores\n“Yeah, so do — <PERSON>, what’s that on the back of your hand?” <PERSON>, who had just scratched his nose with his free right hand, tried to hide it, but had as much success as <PERSON> with his Cleansweep.\n“It’s just a cut — it’s nothing — it’s —” But <PERSON> had grabbed <PERSON>’s fore arm and pulled the back of <PERSON>’s hand up level with his eyes. There was a pause, during which he stared at the words carved into the skin, then he released <PERSON>, looking sick.\n“I thought you said she was giving you lines?”\n<PERSON> hesitated, but after all, <PERSON> had been honest with him, so he told <PERSON> the truth about the hours he had been spending in <PERSON>’s office.\n“The old hag!” <PERSON> said in a revolted whisper as they came to a halt in front of the Fat Lady, who was dozing peacefully with her head against her frame.", "573" ], [ "“She’s sick! Go to <PERSON>, say something!”\n“No,” said <PERSON> at once. “I’m not giving her the satisfaction of knowing she’s got to me.”\n“Got to you? You can’t let her get away with this!”\n“I don’t know how much power <PERSON>’s got over her,” said <PERSON>.\n“<PERSON>, then, tell <PERSON>!”\n“No,” said <PERSON> flatly.\n“Why not?”\n“He’s got enough on his mind,” said <PERSON>, but that was not the true reason. He was not going to go to <PERSON> for help when <PERSON> had not spoken to him once since last June.\nThese are the reasons <PERSON> didn't mention it to anyone. The only time the book mentions anyone else getting this sort of similar detention is <PERSON>, and by then <PERSON> (though not Headmistress yet), could only be superceded by <PERSON> and even upon his intervention might have just brought in another Educational Decree that stated she was in complete control of all detentions.\nTo be fair, once <PERSON> was gone and she became Headmistress, the students were much more rebellious and she seemed to have lesser control than ever.", "417" ] ]

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[ [ "My history. 2 player, my wife <PERSON> and I. 6 games total. All losses. Tonight, I took my accumulated knowledge from BGG resolved to play better AND have fun. 2 player with expansion. We used all 4 Taoists controlling 2 each. I resolved to take my time and try some new stuff. Starting with red move-other-player (MUCH better) and blue exorcise-AND-village (also MUCH better). For the first time tonight, <PERSON> hit the board. We did not have fun.\nWhat I love about the game. I love the theme. The art is terrific. I'm a big fan of co-operative games and I like the puzzle solving aspect. The different Taoist powers are clever, as are the villagers. I am sincerely motivated to beat it.\nWhat I don't love about the game: see below.\nDreadful rulebook. Let’s start at the beginning. I've read bad rule books. Lots of them. Goa? Massive suckage. Mall of Horror? So bad its kind of funny. But Ghost Stories takes the cake. It is one thing to be obscure, which it is. It is another thing to leave out how to handle important situations, which it does. What puts Ghost Stories in a special category are the contradictions that significantly effect play. Is there a difference between placing buddhas in any empty space and only adjacent empty spaces? Yes. What about the difference in reduce pips to 1 and by 1? Huge. The worst part: the rules contradictions are so significant that they undermine my confidence in the forum.\nUncertainty in the forum. I love BGG.", "118" ], [ "When someone is having problems (like me), the community rallies and really goes above and beyond to help out. Moreso with Ghost Stories. The fans in this forum are really great about posting helpful hints all the way to full blow by blow sessions. It really is amazing. But here's my problem. Confusion in the rules leads to a lack of confidence in the forum. I've read threads where people come out and say \"I kick the ass out of Ghost Stories regularly\" or \"Here is what you are doing wrong\". Sometimes, the people confidently sharing their experience realize that they had been playing incorrectly. I just don't know if I can trust what people are writing and I don't blame anyone (except the publisher) because the rules are so misleading. Is this person using the same ruleset as I am? Are they playing it right? Am I playing it right? It's like when I tried to play Descent with 2 players. I'd say, this game doesn't work as written and here's why I think this. People would write back and say, well it’s a great game IF you select the strongest characters, or IF the overlord plays more like a friendly DM, or IF you play with our house rules IF, IF, IF... I lost faith in that forum because I had no idea whether I was playing the same game as everyone else. I really do want the help and people are so generous but I just can't shake the nagging lack of confidence that everyone is playing by the same rules. That stinks.\nDifficulty is imposed on you. The initiation level is insanely difficult. There is a variant for reducing difficulty but the rules make a point of actively discouraging you from taking the help. Thanks.\nThe game is too long for recurring failure. Our games are taking an hour to an hour and a half to play. That is a long time in my otherwise busy life. I could be playing Guitar Hero!!! The failure and pain is constant like an hour of groin kicks on America’s \"Funniest\" Home Videos.\nOverwhelming randomness. For a puzzle game, some randomness is essential to generate a varied experience. In GS however, the random elements are just too dominant and obtrusive. The color dice are too unreliable, the curse die can cause dramatic swings, the card order is huge, some bosses seems much tougher than others, the pattern of the village tiles matters, and even the order and powers of the Taoists seems to make a significant difference. GS is a huge teetering pile of random crap with chaos shoe-horned in at every opportunity. Too much randomness diminishes the significance of your actions and dissolves the illusion of free will.\nPlans are transient and meaningless. We would generate little plans. Red will do this, ooh and then green can do this, and ah yes, then blue will then be able to finish that big four black tormentor! Yeah that'll work. The problem is that your planning is a delusion and doesn’t make any difference.", "884" ], [ "Short answer: no, not in our house.\nLonger explanation:\nWhen Scythe appeared in the BGG \"hotness\" about 2 years ago, I was a bit intrigued. There wasn't a lot of information on the game, but the art was quite nice. I'm also a huge fan of Stonemaier Games because of Jamey's professionalism, the company's dedication to quality and because Viticulture is a game that I adore. To be honest, when Scythe was on Kickstarter, I was interested but mostly in the art and components. However, in the last year, I've become more and more interested in the actual game. I was itching to get my copy in and give it a go. The fact that it was supposed to play well with 2 made me even more excited about trying it out. I got my copy this week and I've played it twice. What did I think?\nI think Scythe is a well-balanced game. The playtesting is evident and it's clearly not some glorified prototype. It's also BEAUTIFUL. The components are gorgeous, minus the boring action piece--which incidentally is the piece you use the most during gameplay. The art is well done and the colors are divine. As soon as I opened the box, I was in love. I'm all about pimping my games, sometimes with Jamey's bits , and its extremely satisfying to open a box and know that you don't need anything else. It's all there--factory pimped. Next, I read the rulebook (which is also very well done), setup the game and embarked on a new gaming adventure with my wife.\nSo what happened? If I'm such a fan of the publisher/designer and love the bits, then how was this game not a lock? It's simply because this game is a bore. The gameplay fell completely flat. Admittedly, the first game is somewhat of a write-off. You have to learn the balance and timing of the game, and its hard to really excel at either of those during your first playthrough. After that first game, I told my wife that either we need to play it again or we need to get rid of it. You see, I'm perfectly okay with playing a game once, and if I like it, I can shelve it for later plays. Essentially, that game is considered \"safe\" and well-liked. There are many games, however, that require a second play. That second play is typically focused on one of four things.", "386" ], [ "That is, either the game is broken, it's so fantastic that I have to play it again right away, it's not good with 2 (and needs some variant) or we just didn't enjoy it and hope to enjoy it more the second time. Scythe fell into the last category. Our reaction was essentially \"meh, that's it?\"\nAfter that first play, I got on BGG and did some research. I was trying to understand why people enjoyed this game so much. I enjoy research anyway, except when it leads to spending money . I read reviews, I read up on some basic strategy, session reports, you name it. I was convinced that I was missing something. After reading SO MUCH positive feedback about the game, I was determined to play it again. This time, I would play tight and clean. I would get my engine producing quickly and above all, focus on timing.\nSo how did it go? The problem was that I just wasn't having fun. Here's these great pieces sprawled out all over the board, art that oozes with theme, combat, exploration, etc., but the whole time it just felt soulless. Despite all that effort and all that chrome, Scythe just didn't seem to have any character. It was simply an efficiency game, bland and uninspired. I don't have anything against efficiency games. What's Your Game, a well-known publisher of medium-heavy weight eurogames, has produced some games that I really enjoy (e.g. Vihnos, Signorie, Vasco da Gama and Madiera). I don't need a lot of theme, and I enjoy games that focus on efficiency and balance. Scythe, however, seems a bit disingenuous. When I go to play Vasco da Gama, I don't expect to smell the ocean or feel the wind in my hair. I don't even expect to remember what the theme is halfway through the game, and that's okay. But with Scythe, you expect something different. You have this gorgeous package that ostensibly tells a story, has tremendous character and produces excitement. But what you really have is a gorgeous veneer over a lackluster game. And I hate to say that, because I know that this was a labor of love by a designer that I respect. But that's how I feel.\nSo how do I grade Scythe overall:\nArt: 9 out of 10--absolutely beautiful!", "386" ], [ "Ok, I've given away my conclusion: I really really REALLY like this game. Now before I give my full review, a few disclaimers and clarifications:\nFYI, I've played 10 times, 2 solitaire, 1 with 4 players, 4 times with 5 players, 3 times with 6 players. So my sense of the game is perhaps limited. But I thought it was important to get a few more reviews out there because I really think this game deserves the love.\nSecond, I'm not <PERSON> (bless his hard-working heart) who seems to love 90% of the games he reviews. I'm often a grump where games are concerned. If I love you, great; but if you don't measure up, I sneer and throw you on the trash bin.\nNext, I got this game with no preconceptions. I was shopping at my FLAGS and saw this on the shelf and thought, hmmm. I glanced at some good ratings on BGG so I knew it wasn't a total gamble, and bought it. Usually when I do this I'm sorely disappointed. (I'm looking at YOU Dust Tactics). This time I got lucky.\nFinally, my background: I began life as a wargamer (Avalon Hill games, Tactics II, Blitzkrieg) but have steadily moved in a more Ameritrash and Eurogamer direction. Most of the time these days I'm playing Agricola, Terra Mystica, Age of Conan etc.\nSo now the review...\nOverview\nQuartermaster General is a card driven game which tries to roughly simulate World War 2. It can play from 2-6, scaling up beautifully. (And strangely, having more players usually means the game goes faster.) Its clean mechanics and lack of dice make it feel like a Euro Wargame. (But only if you think that's a good thing!)\nComponents\nThe quality of the components is very good. The board is a solid piece of cardboard, vaguely Risk-like in appearance, although with fewer provinces, and with a turn and victory point track going around the edges.\nThe pieces are wooden tanks and ships. They aren't especially evocative (I'd prefer some fancier more tank-like or ship-like sculpts) but they do the job and are much nicer than some silly cardboard chits. A big shock when you open the box is how few pieces there are.", "366" ], [ "The bigger countries have a total of 10, the Soviet Union 8, Italy 7. Not to worry, the game design makes the small piece count work perfectly.\nThe cards are excellent quality, safe to riffle shuffle (although I still don't because, well, you know, neurotic). These cards will clearly take a LOT of playing. I don't love the art on the cards. It seems too generic and I don't like that the images are the same for all the countries--although the flag waving in the background changes, of course. Obviously, opinions differ. Many people simply love the card art. [And the art has grown on me since first penning this review.] A bigger beef is that the detail text on the cards is smaller than it should be. It's not crazy tiny like some games (Imperial Settlers) but it was small enough to make life harder for one of my fellow players (to be fair, the room WAS dim). I don't want to exaggerate this, my 51 year old eyes did fine, but if you generally use reading glasses, you may want to keep them nearby for this game. However, I think my card quibbles are exactly that: mere quibbles.\nPlay\nFirst, learning to play is a breeze. The rules aren't complicated and the rule book is well written and clear, with pictures and examples. From scratch, I think you could be up and playing with 20 minutes. I explained the game to a group of first time players in about 10 minutes.\nGame play is super clean. You have a hand of 7 cards, you play 1 and only 1, you discard any cards you want to dump, you count your victory points and draw your hand back up to 7. SUPER SIMPLE! The only tricky part is remembering to move your victory mark up the victory track after every country's turn.\nCards do essentially one of six things: destroy 1 neighboring unit (battle), build a unit next to an existing unit, set up a status, set up a response, wage economic warfare, trigger an event.\nStatus cards are always active cards that can effect play as the game goes along. They stay face up in front of you for the rest of the game. A sample status card: the Germans have a card that increases the damage done by every subsequent submarine card.\nResponse cards are played facedown and then turned up whenever the owner wishes, usually as a response to something the enemy has just done.", "993" ], [ "I had a chance to play my first and so far only game of Lagoon:Land of the Druids on Friday night (in a very public performance vian and Unpub Live Play!\nYou can watch the game and ensuing discussion here...\nhttp://www.youtube.com/watch?v=odd5Tv3xlQM&feature=youtu.be\nI wanted to take a few minutes and jot down my thoughts on the game for those unable or unwilling to take the time and watch the video. Please note these are all thoughts after 1 play of the game.\nMy preparation prior to the game was reading the rules and we played a few sample turns before the game to make sure I knew what I was doing (both <PERSON> and <PERSON> had played before.) I found it very easy to learn. I think I caught on quickly enough and we hit a groove really well inside the game.\nWhat makes the game \"complex\" are the actions on the tiles. There are a lot of possibilities of actions to take based on what is available. The field is always changing and that does make it a little hard to plan ahead.\nThose who are going to be upset with AP...well, they're probably going to be upset with Lagoon because it is going to create those moments where players are saucing out the best turn possible. Frankly, that's where the game lives in solving an ever changing puzzle and I'm really okay with that. I loved it. Yes, I can think of a few people I won't play the game with because it will be excruciating, but there are many more I would gladly put this on the table in front of and we'll have a blast.\nI also really appreciate the fact that the game doesn't allow players to hold back special cards for kill moves and power plays. If you're going to make a huge play, It's on the table and everyone is going to see it coming and very often have a similar opportunity to make it happen. All players have the same tools to work with.", "755" ], [ "...Yes, sometimes a player will draw a tile that is exactly what they need, but sometimes ...just as often if not more-so, a player is not going to draw what they need. It's a pleasant conundrum and I'm good with it.\nThe trick to remember in this game is that it's not about area control. It's about Occupancy. You simply need to occupy something for each of your Druids to have that ability. It's a seemingly unique twist on \"worker placement\" that I quite enjoyed. I don't think I employed this mechanic as well as I could during the game I played, but I did appreciate it and will exploit if further in the future.\nI loved the concept of unraveling. I really liked the scoring mechanism at the end though I'm going to be cognizant in future games when the tide turns and what that means for certain players. How many get totally decimated by a major shift and how long the game lasts after that.\nI thoroughly enjoyed my first game of Lagoon: Land of the Druids. I am looking forward to more games of this in the future. <PERSON> has created something that looks great, plays well and will be very much appreciated by a great many intelligent gamers for years to come. I am glad I had this opportunity to play Lagoon.\nThanks for reading.", "755" ], [ "Race for the Galaxy is one of the greatest meatiest card game experiences of all time. <PERSON> tantalized BGG with his designer preview of Jump Drive which is a re-imagining of the RFTG theme in a completely new card game design. Race for the Galaxy utilized simultaneous action selection: exploring, researching developments, settling worlds, and then using those worlds to produce goods which could then be consumed for income (more cards in your hand) or shipped off for victory points. It was the first game I played where I had a hand of cards and these cards could be used for different things. Should I save this card for a later turn? Should I build this development or spend it as currency to colonize this planet card? You had to race against the other players to explore the deck and find cards to chain together into combinations to suit your strategy. What does Jump Drive do differently? Is it worth picking up if you already have Race for the Galaxy?\nOne of the most notorious reputations Race for the Galaxy got was that it was difficult to teach. There were many symbols. There were symbols that affected other symbols. The actions were symbols. Cards had special abilities that were symbols that might refer to other symbols. Not only did you have to explain the overall objective of the game but you also had to explain how to use six different actions to get there. Cards could give you victory points and cards could BE victory points. There were military worlds, resource planets, and windfall planets. Naturally, this was very overwhelming for new players.\nIn steps Jump Drive. In Jump Drive, everyone plays simultaneously. You can EXPLORE or you can build 1 or 2 cards out of your hand normally (either placing a development-diamond symbols at top left- or settling/conquering a world-circles at top left of card-). You get a bonus if you just play one card. If you play two cards (must normally be one of each type: development and planet) you don't get the bonus but pay the full cost. Each turn your cards score VPs and give you income. That's it. That's all there is to Jump Drive. There are still some symbols to learn.\nMost symbols are aligned on the left side of the card.", "697" ], [ "Once built in your tableau, these add to your abilities and can chain with other cards. Eyes give you the ability to look at more cards when you EXPLORE. Military symbols of the red circles with a red +1 inside add to your military strength which allow you to conquer military worlds without the need to pay cards to settle them. There's some green gene symbols that you can chain with other green gene symbol cards to give you multiplying VPs and/or income. There are different colors of planets that you can chain together. Many of the expensive development cards provide you with an overarching strategy to aim for to maximize VP production. This is really all you need to know.\nWhat is it like to play? It is fast. If Race for the Galaxy is a two lap competition, Jump Drive is a 100 meter dash. It captures the essence of Race for the Galaxy and turns it even more into a sprint by stripping off all the extra weight. You no longer have to produce goods and ship them for VPs. You are racing to get the cards you need out of the deck and onto the table. You are racing to find a viable combination to chain together. You are faced with agonizing decisions each turn to build, spend, or save cards. Or even skip a turn of building in order to explore.\nThe decisions are just as meaningful as Race for the Galaxy and it preserves the motif of \"racing\" through the galaxy, discovering planets and technologies, and trying to do it faster than your opponents. In fact, I like it better than its older brother. I find that I can teach this in 5 minutes flat and get someone playing right away. Gamers may crave the bigger game with its more complex chaining and timing that is required to produce goods and ship them. My wife, who has refused to play Race for the Galaxy in the past, gave the most fitting response after playing Jump Drive several times. \"I like this game! It gets rid of all the shipping.\"\nJump Drive is far simpler to teach. It plays faster. It captures the essence of all that I loved in Race for the Galaxy. It is now my go to filler card game!", "237" ], [ "Eclipse is a game that I had my eye on for awhile and when I got it, I wasn't disappointed. It now proudly sits atop my rankings alongside Diplomacy as a 10. I love long civ games, and multiplayer conflict games. I love complex, chaotic game states that provide multiple avenues of progression. I love the table talk, giving \"advise\", bluffing my own power, deflecting others from my weak points, big epic unforeseen moves and the ability to also win peacefully. Eclipse has all these things. I also like a good Euro. I own and enjoy Agricola, Puerto Rico, Power Grid, and my new favorite; Dungeon Petz.\nSo what is Eclipse?\nEclipse is a space themed clash of civilizations with tech research, ship building and designing, with an economic engine that any euro would be proud of. It is not a euro though. While competency running the engine is a requirement to do well, the main strategies revolve around being a excellent diplomat and general.\nEclipse is also a deep and long game. You should not expect to play well vs experienced players on your first go. (you may do well, you just shouldn't expect to)\nWho's going to like it?\nPlayers who don't mind longer games. First games appear to be going along the lines of 1 hour per player with the box time of 30 mins per player being reachable after a few plays. 7 Wonders this isn't.\nPlayers who don't mind conflict. This is a game that requires conflict. There may be a rare game as a player where you run into no ancients and no one attacks you, but most games will require an offensive at some point if you are playing to win.\nPlayers with an open mind. Certain strategies are more obvious than others. It's not immediately obvious what force is required to take down an ancient. It's also not immediately apparent what the value of an action is, or that saved actions can be more valuable than ones used early. (and many other strategies) The difference in exploration tiles has caused a debate on whether the game is balanced. I'm of the opinion that the perceived imbalance is with new players getting tiles that require the less obvious strategies, or a strategy they are disinclined to go with (a peaceful player not wanting to attack). Please know that I don't consider all people who dislike the game to be closed minded. But I have seen people in my own play group dismiss the game as too random even though I saw them making mistakes they wouldn't acknowledge.\nPlayers who will play multiple times. The complexity of strategy means multiple plays are required to get the full impact. Can you enjoy one game? Sure, but it's one of those games that you don't quite see what is going on until some portion of the way through your first game. This encourages some people to play again. Others aren't interested in that level of time investment.\nPlayers willing to see through a slower start.", "237" ], [ "This game is as much about perception of strengths as actual strengths. You can come from behind, I've seen it done. I've also seen players lose an early battle and essentially give up. The game rewards perseverance. Not every time. If you lose your first ancient battle, you are indeed behind and odds of winning go down. But not all the way to zero! Stay focused, regroup, find a different way through. Because there is dice, the luck can swing back your way. Because there are other players, you can still participate diplomatically. In Diplomacy, I've come back from a two center Russia to climb back into serious contention. The same can be done here and is all the more rewarding.\nWho's not going to like this game?\nPlayers who like short games. As stated before, a beginner game is around an hour per person. You get to the half hour per person after a few plays. If this is too long, you won't like it.\nPlayers who don't like dice. Dice are in the game. I'm personally okay with the amount (I wasn't with Risk and the original Axis and Allies). If you don't like dice at all, don't bother. I think the luck of the dice present is good. I'm also okay with losing the occasional \"can't lose\" battle. I will risk a few fighters with 80% odds and be fine with losing them every so often. I'm even okay with losing a 99% battle. It's dice.\nPlayers who are thinking this is pure euro. It's not. Trying to play it like one will make it unbalanced and you unhappy. The game assumes some level of ruthlessness in taking on other players in battle. You might need to eliminate someone.\nIf you don't like combat, it's not for you.\nPlayers who don't like the theme or a heavy game. 'nough said\nA quick note on bits.", "237" ], [ "Please check out my Geeklist at:\nhttps://boardgamegeek.com/geeklist/145695/purge-reviews-reco...\nMy video reviews can be found here:\nwww.youtube.com/purgereviewsboardgames\nConclusion:\nLong Shot was my favorite horse racing game and one of my go to party games. It accommodates a lot of players and everyone understands the concept of horse racing. It was and is an easy sell so when the Dice Version was released promising to be smaller, quicker, and just as good I have to admit I was intrigued.\nLong Shot the Dice Game improves on the original in almost every way. I will list a few pros and cons to this game:\n1. The game is short. It usually takes about 30 minutes to play the game. It doesn't over stay its welcome and plays in about the perfect amount of time. The original was more like 60-90 minutes so this is an improvement but you will need another game to play on the same night where the original was a game to center the night around.\n2. While I really like the look of the game, the original is larger and fills up a table better. A lot of people are going to like the compact nature of this game, but it is a tad small for 8 people. I may be in the minority, but I would like a Jumbo version of this game. Larger cards, bigger horses, etc.\n3. The game is easy to teach. You roll some dice and everything works off the dice. People understand instantly the roll and move mechanic and betting on the horses. It takes just a couple of minutes to teach the game and most people will be able to play without any questions.\n4. The game is full of luck. That's the game. It is all about profiting off that luck and pressing your luck to generate more and more cash. The horses are going to move on their own, but you can start to add marks to the horse to influence the horses you want to move. I guess that is the best way to comment on it: you are trying to influence the horses and the outcome. Some people are going to like this and others hate it.\nOverall, I have to admit I love this game.", "581" ], [ "I've been playing the solo game over and over trying to beat that <PERSON> character. I've played this with a lot of different player counts and it does a good job of keeping you invested when it isn't your turn. The game mitigates this by letting you take an action on other players turns. That's a great fix.\nI can highly recommend this game for people who want a horse racing game and like to have fun. This is a dice rolling, horse betting, take out your opponents good time and one I'm willing to play anytime.\nKeeper.\nComponents:\nThe components are top notch for a roll and write and a light filler. The horses are silk screened on both sides and fit the smaller board perfectly. The dice are a tad on the cheaper side, but they do get the job done. You get plenty of dry erase markers which are pretty standard for this sort of game. Everything has a great look to it and I like the choice of sillier art work. The package is very, very good for the price point.\nRule Book:\nThe rule book takes about 15 minutes to read. The rules are full of color and has plenty of pictures and examples. This is a very easy to read rule book and everything seems to flow perfectly as you read through the rules. The book is easy to digest and to use as a reference while playing.\nFlow of the Game:\nThis is a horse racing game. The race is over when 3 horses finish the race. Each horses is awarded a place (1st, 2nd, 3rd).\nPlayer Turn:\n1. Roll both dice\n2. One die is the horse to move; the other die is how many spaces to move (1-3 spaces); then move all the horses listed on the card 1 space only\n3. Then, each player takes an action in turn order based on the die identifying the horse:\na. Bet on the horse rolled\nb. There is a chart where if you finish a line you get money, free bets, move the horses, etc\nc. Add a helmet - this allows you to bet after the horse crosses the no more bets line\nd. Add a jersey - this allows you to mark for another horse to move when this horse is activated\ne. Purchase a horse (each horse as a power that is activated when the number is rolled)\nYou score points if a horse you own places, each helmet/jersey combo is worth 5 points, gain money for bets plus any money left over.\nMost points/money is the winner of the game.\nShould I buy this game?", "629" ], [ "Got a chance to play this exciting game at GenCon. I admit I only played a couple times, but I thought an early review was better than none given the lack of information. My short bit: just an awesome game.\n0. Description\nIn Endeavor, the players are European powers that set out to explore and colonize the world. Each turn is very phase driven, you:\nA. Take 1 new building.\nB. Take some new dudes from the supply.\nC. Remove some dudes from your buildings to make them available again. (Buildings are not like in Puerto Rico. They trigger an action when occupied, but then need to be freed up to be used again.)\nD. Take turns making actions with your dudes. Most actions require you to put a dude on an open building and then place a second dude on the map. The exception is one action lets you draw a card.\nE. When you pass, you apply your hand limit on cards and once everyone has passed you do it all over again.\nThe player board has 4 important tech tracks. They more or less correspond to every phase above except D. (One track lets you get better buildings, the other lets you grab more dudes from the supply, the other lets you unload more buildings and the last lets you hold more cards.) All the map locations are seeded with tokens that correspond to a tech track. When you occupy a space on the map you get the corresponding token and update your progress on the corresponding tech track. The cards also show multiple tech icons.\nIt is a VP game and most of your score comes from 2 places:\nA. You get points for how far you progress on each tech track.\nB. You get points for your board presence in cities and the connections between them.\n1. Analysis Paralysis / Downtime\nThis game just SHINES on the AP front. Turns fly by so dang fast. All the accounting can be done simultaneously, so the only part of the game that even takes a moment is playing out the player actions. And even that flies by in such a hurry. You are only presented a few options each time, but they sort of compound to make sure they feel different.", "629" ], [ "You only have a handful of buildings to choose from each time, but what buildings you choose determine what handful of actions you are going to have available. So viewed one at a time you never have huge choices, but the consequences get bushy.\nYou also can't plan out your entire game from the beginning, so it does stop that whole \"waaaay forward\" thinking. The space on the map is limited and the other players are competing with you for it.\nEven in a crowded loud convention hall with 4 newbies and one teacher the game did not last over 2 hours. That's a small miracle of sorts.\n2. Frequency of Meaningful Decisions\nThere are no stupid decisions in this game. They just don't ask you to make them. I love that in a game. Grabbing a building is a damn hard choice. It can dictate a lot of your strategy.\nDeciding what actions to take and in what order can be excruciating. You want to do everything, and you want to do it now. And you will just not be able to do so.\nThe only stupid decision in the game is discarding down your hand in the final turn. It just turns into some silly min/max exercise that has way too many permutations to complete easily. Luckily you can do that while other players finish up their turn.\n3. Multiplayer Solitaire / Player Interaction / (Competitive / Casual)\nWell, this is not solitaire. There is a map with a limited number of locations. You all want to be everywhere and it's just not going to happen. As if that wasn't enough, here's a couple more great glitches:\nYou *can* outright take over another person's city. To do so you need a cannon action. You must trigger the cannon action, then sacrifice one guy to your supply and then place a second guy onto the occupied city you want. The original owner places their dude back into the supply. War is expensive and both parties involved feel the attrition, but it is very much a part of the game. Why would you do it? Well you need a lot of dudes in one area of the map to be able to draw the good cards from there. Also, there are a lot of \"connections\" between towns that earn you additional tokens and then VP at the end of the game.\nI'll now introduce another important part of the game. You start with only the European cities open and available at the beginning of the game. All the other continents only have \"shipping lanes\" open. When a shipping lane is full, then the cities become available (but only to those who partook in the shipping lanes.", "629" ] ]

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[ [ "Canidae All Life Stages\nHello, I have looked up some threads but they are all so old that I am sure the recipes have changed since.\nI just changed my dogs to Canidae from Purina Pro Plan. (I am fine with Purina but my border collie's poos were way too hard and he started having issues with colitis so I decided to try something new.)\nI am just wondering on recent opinions, experiences with Canidae all life stages food.\nFor me it is really great on my budget with three large dogs, but I still want to make sure they are getting a good food.\nMy border collie has had better poos with it, so so far I am happier with it, but my labernese is actually getting harder poos and hers were perfect on purina so I am of course just going back and forth on if I should find something different.\nI had great experiences in the past with Zignature and was thinking of going back to that but of course that is a huge increase in cost VS Canidae, but pretty close to the same as Purina Pro Plan now that they charge an arm and a leg as well.\nThanks!", "63" ], [ "Desperate - Need a food alternative!\nHello fellow fur parents,\nI come here on my knees, in search of advice and suggestions, after I have done my research. I'll try to explain while keeping it short.\nI have two Furs, ages 4 and 5 who have grown up on Purina pro plan since kitten hood. Since the pandemic, whatever has happened with the formula is noticeable to these picky ones and they are not pleased! I have tried so many different brands and I don't know what to do. At the end of March, I noticed the 6 year old gagging. Thinking it was a lodged hairball, we ran to the vet, who believes he had nausea and a possible kidney infection.", "747" ], [ "Urine sample later found crystals so I know his diet will have to change. Meds have been working but now I went to feed him tonight and he is gagging again. As if the tuna flavor is poison! I am going on vacation next week and don't want him to starve. I know that they specialty brands require vet approval (Chewy) and we are in the process of finding a new doctor (unprofessional, no availability, extremely high turnover/red flag). I am also tired of wasting money and not finding a worthy alternative.\nI know they all have their own likes/dislikes but what have you tried that has worked?\nAny help will be greatly appreciated. I am desperate and will do anything for them.\nThank you", "747" ], [ "Any advice on dog wards?\nI have a 10 year old poddle mix and I noticed that he has a couple of wards on his back. During his annual physical a couple of months ago the vet told me that wards are normal for older dogs and that I shouldn’t worry.", "63" ], [ "However lately they seem to be growing and I am not sure what it means. His vet won’t have any available appointments until the end of August and I am not sure if I should wait until then or take him somewhere else. I would really appreciate any advice from other dog owners who have experience with this.", "961" ], [ "Cat has dry fur - how can I help him?\nHey guys! I have noticed recently that my cat has had some dry fur and some flaky skin (maybe dandruff?). I try to brush him every day, because he loves it a lot, but I am wondering if this is making it worse. He is on the larger side, but putting him on a diet is difficult because I have another, smaller cat and I want to make sure she has enough food as well.", "505" ], [ "They both also have dry food, and I am wondering if wet food could help with this problem, or if there is something I could put on his fur. I want to make sure he is not itchy or uncomfortable, and he hasn't indicated that he is but I am still worried about him. Does anyone know what I can do?", "833" ], [ "Cat's allergy test results\nI couldn't take it anymore and finally ordered a blood panel. I was hoping someone else who's been down this road would know what I can do to mitigate her reactions.\nShe overgrooms mostly on her belly and back legs so it could be something she sits on like dust or cotton. And sometimes I burn candles which makes me think of her high positive to pine. Could be in other household items as well.", "664" ], [ "I also plan on staying on top of dusting and vacuuming. Does the dust in litter count as an allergin?\nAs far as food allergies, they gave me a list of food from different vendors she can have. For dry kibble, she can have Hills pet nutrition, Natura, Royal Cain, Taste of the wild, Wellness, and Zignature. Does anyone have strong opinions on any of these?\nAny tips or advice are much appreciated! Thanks!", "747" ], [ "At home rememdy for pets\nSo my dog is really rough and tumble but I think her age is starting to show (ain't that the truth...). Usually she is fine but lately she is getting hurt. She will be running around and after we head inside and wind down I'll find her limping. The few times it's happened there was a substantial amount of time in between coming inside and the limp so I can't really identify the cause.\nShe is a 7 year old Patterdale Terrier mix. We are on a 2.5 acre lot with lots of lizards to chase ranging from little anoles to dinosaur iguanas.", "664" ], [ "The iguanas like to chill on the rock structure for the waterfall and she likes to chase them everywhere and swim in the pond. Her and I also live in a travel trailer with metal steps at the front door. Thus far, the worst thing to happen is she gets some belly scrapes from the rocks, although she would say the worst thing that happens is her post-swim bath. But I suspect she has either been banging her leg of the metal steps on her aggressive leap out of the trailer or she is getting hurt on the rocks.\nWith the little I remember from the scouts and my time as a vet tech I gave her a pretty good once-over and she doesn't seem very painful upon palpation but her from leg is swollen at the first joint above her paw. She can walk on it and still jumps onto the bed (there is literally a perfect set of steps and she still jumps) but is also still limping and behaving abnormally.\nAnyway, what can I do to help her out at home since we cannot afford a vet visit right now?", "881" ], [ "I think my dog is underweight.\nI have a 7 year old miniature poodle and she currently weighs 11lbs. She is really tall and boney, the vet said she has weirdly long legs and was compared a “baby deer” lol.", "63" ], [ "My attempt at getting her to gain weight don’t seem to be working, I add coconut oil, eggs, white potatoes and chicken (all cooked) to her dry food. Which is Natures recipe dog food and she just doesn’t seem interested even tho she’s really greedy when I come to table food/ human food. So any tips on what to feed or what diet to use?\nI recently had to shave all of her hair due to some matting and noticed how frail she actually looks.", "747" ], [ "Help!\nMy dog just got his leg bone out of the pubic bone after an accident with a much bigger dog that did not have a leash on. We got him to the doctor, now his leg is back on, he needs to have some cage rest for 2 weeks.", "833" ], [ "Now the big question, how can I make him do his needs inside? He is 14 years old and almost never poops or pees inside. He uses his leg a lot when he pees and poops. What should I do? What cand be done for him to get to poop inside on a poopie mat? (They told us at the vet that he should poop any minute but we have yet to see that, it’s been 6 hours)", "833" ] ]

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[ [ "Baltimore\nA lot of disparate elements that I really liked but never feels like it comes together, while certain choices seem gratingly self conscious.\nThe film works best when it plays into the enigma of its central character but too many times it undermines this and presents things in ways which feel too obvious. Flashback scenes of student revolution are awkwardly staged with dialogue which knocks you over the head.", "269" ], [ "The supporting cast feels very underwritten and seem very much to be an afterthought, As much as an actor of <PERSON> calibre might try.\n<PERSON> is good and embodies the contradictions of her character nervy, angry, arrogant and unsettlingly calm, all at once.\nThe score is great, in many ways it is the film, without it I’m not sure if it works at all.\nOne nitpick. Throughout the film the <PERSON> refer to Northern Ireland as well… Northern Ireland. As any one from Northern Ireland can attest they almost certainly would never call it that, it would be “The North of Ireland”, small difference but stuck out like a sore thumb at times for me.", "909" ], [ "The Royal Hotel\nThoroughly enjoyed. <PERSON> has the juice and can direct actors better than almost any of her peers.\nI would describe this as a successful attempt to take a lot of the ideas behind The Assistant and reapply them to a different setting and genre. It’s a film for a big crowd and it works extremely well.\n<PERSON>’s strength is in her character work. She never takes an easy out for the sake of drama, and even the villains of this film are full of contradiction and drawn with a lot of empathy.", "657" ], [ "Surprisingly a significant amount of the conflict exists between the two leads, and their different approaches for dealing with drunken chauvinism. At times this dynamic felt mildly underwritten to me, however I feel like I owe the film another watch while considering this relationship more.\nThe real revelation here compared to The Assistant is how <PERSON> blocks and shoots her scenes. Most of the film is set in a fairly packed bar, with around a half dozen distinct patrons. Fantastic use of the space is made and the camera always feels like it is finding the most interesting spot. <PERSON> knows when not to show certain parts of the bar and a lot of tension is mined from a fear of what might be happening just outside the frame.\nMost importantly performance is king and the actors are never lost in the fray while trying to show off with a set piece.\n<PERSON> is sensational once again.", "217" ], [ "Orion and the Dark\nReally didn't love the personification of ideas, and honestly feel like no film has touched the magic of Inside Out when it comes to this but it came together in a fun way. It actually weirdly just takes away from the messages of the movie as it's completely obvious what this is immediately, personified metaphors are fun when there's some more layers.", "823" ], [ "I feel like the story is not deep enough to warrant the excessive metaphors.\nWas really shocked at how this looks a lot worse than most animation films releasing at the moment. It looked really cheap especially coming from a large studio.\nI enjoyed <PERSON>'s existentialism riddled script but I don't think he managed to balance being dark and comedic, I don't think children or adults would either get enough out of this, feels both simultaneoulsy made for children and adults and also made for neither. Jokes about Sundance and <PERSON>, who is this film made for?!?", "698" ], [ "<PERSON>\nAdmittedly, I did not register this as a comedy until 40 minutes in at which point after realizing this everything the film was doing became crystalized and threatened to break the film in two. The mood piece about alienation as an immigrant worker is nearly overtaken by a dead pan humor that is somehow too arch and too subdued, best exemplified by <PERSON> performance that threatens into becoming a caricature every time the film returns to him.", "132" ], [ "Fortunately, the film finds it's footing again at it's closing with <PERSON> mechanic. Very much of a piece with <PERSON>'s Fallen Leaves as a film that perfectly captures the feeling of living in current moment even if it isn't as fully realized as <PERSON>'s film. I imagine this plays better in a theater with an attentive crowd.", "529" ], [ "Deal of the Century\nMan, what a film of heights and lows. On way hand this has some great moments with some of the nastiest criticism of <PERSON> era that the studios ever made. <PERSON> himself is a pretty major character to the film and <PERSON>’s script even name checks some real life war profiteers like <PERSON>. To think a film with this much poison could come out a year before the last major electoral sweep. That’s even without going into the film’s contemporary relevance through questions on drone usage.\nThere’s also tons of great little moments.", "698" ], [ "The best being <PERSON> cameo which most perfectly hits the comedy and satire that the film is aiming for.\nUnfortunately all of that is choked by the main trio who are miscast and poorly written. <PERSON> seems uncomfortable playing this kind of villainous protagonist and instead is desperately trying to make this guy a proto <PERSON>. It just doesn’t work in a more grounded and subtle film like this. <PERSON> and <PERSON>’ characters both suffer from some inconsistent writing that don’t make a lick of sense from moment to moment in their motivations. In particular the ending seems rushed with these two switching who they are sometimes dramatically between each scene. In all this reminds me of Bonfire of the Vanities in that a few problems of cast and characterization take a great film and make it mediocre with the failure being even stronger here.", "698" ], [ "Poor Things\nI read the book this month and it instantly became one of my favourites. It is such an amazing and many faceted piece of literature that it is hard not to see this film now as a slight failure. There is a lack of ambition in how <PERSON> drops the setting, the framing structure and some level of mystery. It feels like the <PERSON> of 10 years ago might have tried and failed, but perhaps the sense of <PERSON> now is not to try at all. He instead hones in on specific elements of the novel, playing them to perfection.", "647" ], [ "It'd just hard for me not to spend a little time imagining what could have been.\nWhat’s left is a masterpiece in its own right. As so much is excised to focus on the mental journey of <PERSON>. The cinematography, costumes, score, production design. All emphasising what it is like to see the world through the eyes of a child, to be free of worldly pressure, but in <PERSON>’s unique case not to be treated as a child or to know the feeling of being under authority. Perhaps it would be better for the world if we were all afforded such a luxury.\n<PERSON> is sensational, but as is the full cast. <PERSON> really just cannot miss an opportunity to do a perfect line delivery.", "529" ], [ "Bad Times at the El Royale\nThe notion that Bad Times at the El Royale is simply a cheap <PERSON> knockoff undersells the film and suggests that <PERSON> doesn't himself take from a myriad of influences not so subtlely layered all over his own work (even cannibalizing himself if you will in his more recent features) but I digress.\nHere the multi-POV structure I argue hurts the film more than it benefits. While it does lend itself to some interesting twists and suspense the threads don't really amount to any cohesive momentum, particularly in the first two acts that drag. The characters don't intersect enough to build a meaningful relationship even by proxy to one another and the sleight of hand featured in similarly structured films is nonexistent; it is a pure straight shooter that fails to engage consistently for its lengthy runtime. There's no real reason to care for any of these characters, their backstories told through multiple flashbacks provide context and broad motivations but don't really establish characters with much memorable personality.", "952" ], [ "The last act is the best portion of the film but it could just as easily function independently as its own entity. There's a lot of fluff in the runtime that could've been better utilized or cut completely to no real loss to the final product.\nI do however appreciate how this mirrors a specific aesthetic reminiscent of 80s/ 90s pulp thrillers. God knows we need more variety at the cinema and I enjoyed the flair <PERSON> flaunts throughout capitalizing on a strong ensemble of performances and some interesting cinematography choices.\nStray Observations\n- <PERSON> is more interesting as a villain than he is as a hero. Obviously, he has charisma for days but its more interesting (and he seems more invested) when he gets to manipulate that for other means\n- <PERSON> / <PERSON> don't get enough to do here.\n- <PERSON> and <PERSON> steal the movie though", "796" ], [ "One Day\nBy the time it reached the final episode it became clear to me that this was a tv show (book) which had been written backwards. <PERSON> wanting to explore the relationship between memory and grief primarily, but unfortunately also wanting to use the death as a somewhat hacky twist bait and switch, which feels like manipulation designed to heighten emotion in an unearned way.\nAs a tv show I often found it very frustrating. The characters are not written beyond the confines of the episodes and often the places in which we find them each year seem very contrived. In converting everything to this episodic structure it is a lot easier to see these faults, whereas perhaps on the page or in a film there is more flow between the years, a chapter or a scene does not need to standalone as a piece of art, in the same way an episode of television does.\n<PERSON> is really fantastic throughout the series. From scene to scene she is finding interesting line readings and subtle gestures.", "80" ], [ "Elevating the material. She is always working to find the character despite the writing's occasional jumps leaving gaps in her development.\n<PERSON> has moments of brilliance. The final episode will probably make him a star. I found when he was without his co-star there was a lack of focus to his characterisation. He is a new star for a rogues gallery of sad boy actors, but unfortunately his sad character has fairly boring reasons for being sad for most of the series. It is really lazily written, and unfortunately I always felt like Woodall could not hold the weight of the bad writing in the same way <PERSON> could.", "132" ] ]

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[ [ "I'd require a signature count equal to 5% of the affected population before a policy can come up for debate.\nThis allows anyone with a good idea to market and garner support for their idea prior to subjecting it to a vote. If they have a very hard time getting anyone to sign the initial petition, they can refine it until it's acceptable, or they'll eventually give up. If it's a good idea, and has a shot at being made law, 5% shouldn't be a hard number to come up with.\nOnce it makes the initial cut, a waiting period to publicize the proposal is put in effect. I'd think no more than a month. This allows the people to debate the law, without waiting a ridiculous amount of time to where people simply forget that it was even on the ballot.\nAfter the waiting period, the vote is held in which an affirmative Quorum of the affected population has to be reached in order for the law to be passed.", "161" ], [ "If it fails, it has to start the process entirely over again.\nBy requiring some leg work ahead of time, it prevents the population from being inundated with having to vote on every crackpot idea, but prevents law making from being out of the hands of the common person. IMO only letting lawyers write laws is why our legal system in the US is so convoluted.\nBy requiring a Quorum to pass the vote, it prevents special interests from simply buying 5k signatures and then keeping a vote quiet to prevent naysayers from voting. With a Quorum, even if they buy off the initial signatures, they still have to convince a real majority of the population to approve of their idea, not just a majority of the ones that show up to the polls.\n--\nThis kind of \"keep the vote quiet so only people who we like show up\" is a common tactic in the state I grew up in. They passed taxes for raises for certain government workers by only telling the government workers that would get the raise that the vote was even happening. One such election had a little over 100 voters turn out to pass a tax that was levied against 60k+ people.", "161" ], [ "Because using them causes Very Bad Things(tm) to happen\nAll the other banned weapons have this one trait. Chemical warfare is banned because it is indiscriminate, causes mass death, even on both sides, can't be protected against and destroys everything it touches.\nNuclear weapons are the same plus extra world ending sprinkles on top.\nLogically it makes no sense to ban the use of aircraft to sink ships if ships can also sink ships. Both result in a sunk ship. The main difference between aircraft and other ships is where they operate : the sky.\nShips also operate on the open ocean, where as other forms of warfare happen on land.", "347" ], [ "Thus for a very specific treaty like this, you need something bad to happen when aircraft operate on the open ocean.\nFor the time period you have mentioned, aircraft were not yet capable of high altitude warfare with naval ships, they needed to be fairly low to hit them with anything. So we could limit this to low altitude aircraft over the open ocean, so that passenger aircraft and air to air combat is still viable.\nFor an example, we could imagine a very populous migratory bird that traverses the open ocean continuously and goes to the continental mainlands around the world at certain times for breeding or whatever. They are highly tuned to see objects at their flying altitude and follow them in big chains of migrating birds. When aircraft fly near these altitudes the birds become confused and huge swathes of them die from going off course and never reaching land.\nThe impact of this happening after the first few occurrences begins to show itself as significant portions of the ecosystems worldwide go haywire and entire crops and other species start to die off because the magical ocean minerals the bird poo provides the soils aren't present.\nA treaty is created that forbids low altitude aircraft over any portion of the ocean more than 5 miles from the coastline. Provisions are put in place that forbids weapons development for aircraft to target naval ships so nations aren't enticed to try to use them anyways.\nLater on maybe research finds that aircraft created in certain shapes or colors don't trigger this effect, or high altitude bombing becomes a thing.\nThere are other situations that could prove highly damaging that would cause a treaty like that to be signed but it needs a component that makes not adhering to the treaty very dangerous for everyone.", "445" ], [ "No Natural Process will do this\nThere is nothing that will make catfish sentient land dwellers in 10,000 years, short of major, sustained human genetic modification towards this goal, from a better understanding of biology than we have. We probably need 50 years to get to this level of understanding.\nHere are the issues as I understand them:\n1) Fish live in an aquatic environment, which supports their body. Their bones are cartilage, circulatory system and muscles are smaller and weaker than is needed to move on land. Basically, all that has to go. We're looking for a high powered land dwelling musculoskeletal system. This is the big advantage that made whales, dolphins and seals competitive when they returned to the sea. This is a big, brutal fix, and would take a huge number of gene replacements.\n2) fish aren't the sharpest tool in the shed, for the most part.", "335" ], [ "Surprisingly, I think this is easier to fix than the previous problem. We have some genes isolated for intelligence, in 50 years I suspect we'll have a decent map of them. Chuck those into some fish, with the right control sequences, and the fish should grow big brains, which, if the other tweeks haven't worked, will rapidly kill them, due to their relatively sluggish metabolism not being able to support the energy demands.\n3) You'd be attempting to do this all with genes that work in humans, because we're the only sentient creature we know, so the obvious starting point. We're a massive evolutionary distance from fish, and there's going to be a whole bunch of genes that need something else, that work differently, that do something wholely unexpected. With the current state of biology, I'd assume 2-5 years worth of research for each gene. You're going to be replacing at a bare minimum, a couple of thousand.\nIt might be easier to give humans a head that looks like a catfish. I don't know how you'd do that either, but it's got to be simpler than trying to circumvent millions of years of evolution.\nNote: unless the apocalypse happened thousands of years in the future, this is not \"lone mad researcher makes sentient fish\" territory. This is a larger undertaking than the moon landings, involving a similar number of people, with technology we don't have yet.", "335" ], [ "Zero Day Exploits and Over-reliance on Cloud Computing\nA powerful rogue nation-state could cause major damage to the internet infrastructure if they managed to combine two zero day exploits in a concentrated attack on the CDNs which house modern applications\nExploit 1: Break virtualization\nWith cloud computing you are renting space on a virtual server to host your application. There are several of these servers on a single computer, but they are cordoned off, so they can't communicate with each other. If an exploit was found so this communication could happen, you could start accessing other people's software.\nExploit 2: Gain root access on Linux servers\nWell now that I can talk to these other applications, I need an exploit to take control of their servers to install my malware, and hopefully send it on to any connecting computers pushing an update.\nSo How Exactly Would this Work?\nI would make a company for each major cloud computing service which ostensibly has developed an app and hosted it there. In the server code of the app, I would hide the virus, which would do nothing but spread undetected for a long period of time, until it was even in the backups.\nWhat would the bug do?\nThe virus would have trigger (possibly time based) and when triggered it would do two things - Delete any data on the host it could and try to connect to as many servers as possible to spread the virus.\nBy now the worm has likely infected most of the CDNs, so the virus spread is saturating the data links, resulting in widespread outages. ISPs quickly work to partition off infected networks, but that's everywhere. CDNs are cut off, and although the underlying data structure remains, the vast majority of sites are down because the hosting structure is down.\nOver the coming days companies will scramble to recover any data and code they could.", "115" ], [ "Their success will depend on how much of it they had local backups for.\nLong Term Effects\nEventually the vulnerabilities would be patched and some of the data recovered, but much of it is lost. Major corporations in all sectors go bankrupt, leading to a massive worldwide recession, which takes out even more companies. Tech companies have the it the worst, due to the series of new regulations, lawsuits, and customers leaving in droves.\nEventually the economy recovers, but public confidence in the internet is shaken for several generations. People won't trust putting their data up and governments regulations on the internet skyrocket, with different rules for each nation. Some Nations may even choose to completely isolate themselves from the global network. Some sort of massive networked data structures will return, but would look very different than the internet we know today.", "998" ], [ "We should start from <PERSON>'s answer, which basically states that this already happens today. PPE : The degree that runs Britain. Or 2/3rd Cabinet Privately educated.\nAs in my comment on <PERSON>'s answer the distinction would be that this isn't society choosing to educate the leaders of tomorrow for their role from a young age, but family and social connections guiding their own youth onto a know successful path.\nAs these articles demonstrate this can lead to a very narrow range of backgrounds for the leaders of the country. Your two options for why a society decides to recruit 14 years olds specifically into \"political academies\" are to either re-inforce this narrow world view or to expand it.\nReinforce The current crop of leadership is worried that the masses are getting uppity. They want to make sure that the retain their hold on power without making it too obvious.", "714" ], [ "So the insitute a national program to find and develop the leaders of tomorrow. They produce a standardised test, throw it at the relevant year group and award the top 1% of marks with elite education from 15 to 24, followed by placement into junior roles in government offices with a clear path to high level political staff in either MP/Party roles or Civil Service management tracks. Amazingly this \"standardised and fair\" test is as easily gamed as the 11+ and leads to the established elite getting their friends and relatives onto the program and a nice cash saving at home, with a few spoilers thrown in to show the system is \"open\" to everyone.\nExpand A maverick political leader from outside the usual channels manages to come to power, perhaps they were the 2nd in command of a \"normal\" leader as a ticket balance and successfully navigate a succession battle following an unexpected death/scandal. This new leader institutes the same program as above, but their test is focused on apptitudes rather than knowledge and cannot be gamed (for some reason). At 14 it's assumed that teenagers will have a strong connection with their roots, and the post 14 training will emphasise maintaining ties with the source community to retain these diverse viewpoints.", "261" ], [ "Unions\nNo, seriously. I think it's always really easy to overlook the human factors and why they quite possibly would not change even in a technologically advanced future. When the station was constructed, the unions all came together to set working conditions for their members and one of the required conditions was that there be a certain number of human traffic controllers on duty at all times. (Possibly this was even at the insistence of the Trade Union, which runs the ships.) It might have nothing to do with the safety of the computers that could run the show. \"We want guaranteed jobs in the traffic control sector or we're not serving your station.\" So, they bent to the union and now there's some traffic controllers.\nGovernment Quotas\nSimilarly, it could be a government mandate. With automation and computers everywhere, the government stepped in and started setting laws on how humans need to be hired at certain ratios. Or perhaps the station was built partially or entirely with government money so the government simply has stipulated that \"this station needs to employ this many people\" and \"well, we could set up some traffic controller positions\" was how the people in charge of the station met the quotas.", "824" ], [ "Might be the computers still do most of the work, but the station controllers have their own quotas of manual landings to perform so they stay in shape \"in case of emergency\".\nThe Station is Poorly Run\nActually, the computers would definitely do a superior job. Maybe it even was automated in the beginning. But over time the system began to degrade. Sensors would go out and not get replaced. The whole station is running on bubble gum welds and duct tape so throwing a body at a terminal and saying \"Go help these guys land\" was easier than trying to refurbish the sensors and networks required to let the computer do it.\nI'm kind of a fan of very mundane explanations in sophisticated sci-fi stories, lol. I do think it helps keep the story grounded. \"Why isn't this automated? Is there something wrong with the tech? Are the computers too smart? Are they not smart enough? Are there hackers? Aliens? Alien hackers!?\" \"Nope. Governmental regulation.\"", "197" ], [ "OK, My $0.02:\nFirst: Gunpowder isn't just \"Charcoal, Saltpetre, and Sulphur.\" Yes, those are the ingredients, but the ratios between the ingredients are really critical, and there are some interesting production methods that need to be applied in order to make what we think of as real Gunpowder.\nSecond, gunpowder itself doesn't explode, it just burn quickly without the need for outside air. without seriously restricting the expansion of the produced gasses, no explosive or propulsive effects will be observed. Alchemists might understand the principles and uses of gunpowder, but in all probability in a magic system, the presence of \"Flashing Powder\" would probably be the mark of the charlatan. Think of any suggestion of using it in weapons as akin to approaching a general about the combat application of Silly String(tm) (Not that silly string doesn't have combat uses...) Or basing a weapons system on pyramid power.\nIf we look historically at the period where what we think of as \"guns\" took over from the Bow-type ranged weapons, we find that there was a period where the gun was a curiosity, rather than an accepted weapon. The reason that guns finally took over was not due to technologies or logistics, but user training. If you start with a raw recruit, with no weapons experience, a musketeer can be trained in a couple of months, while a skilled archer needs a couple of years of intensive training. It's a subtle point, but it's what provided the tipping event in our \"guns-vs-bows\" debate.", "523" ], [ "If there were other factors involved, that argument could have easily tipped the other way.\nTaking this, assume that your magic is Uncommon, rather than Rare. A village shaman or even a military-trained Archomancer could easily provide some enchantments to arrows (increased range, target seeking, improved damage, or magical explosive, just to name a few) that could easily make up for a lower level of training in the archers corps, and would provide a significant, and ready made multiplier to the bow side of the question. This makes guns, while the principle would be understood, a distant second choice on the battlefield.\nAs to explosives, I don't think that you can restrict those without seriously restricting any industrial capability, or even magical capability. An explosion is a sudden release of energy. Any energy. You're going to have to assume that any rational magical system would have come up with this, even if only by accident. Once the principle is discovered, there's no putting that genie back into its bottle. Under those assumptions, cannons and artillery are almost a given, they just might not be gunpowder-based.", "523" ], [ "When things go fine, they're essentially working at a button factory. The situations where they aren't are when things go bad.\nIn general, space traffic controllers would do a few things:\n1. Confirm someone's intending to land at the station, and verify peaceful intent on approach.\n2. Figure out which docking bay is free for that given ship to use, and indicate to the ship where it is, and provide a note to other air traffic controllers that said dock is being used.\n3. Confirm that ships leaving a docking area have clearance to leave/aren't on lockdown, and that the area is clear for them to leave.\n4. Keep track of when ships leave a dock and that dock opens up for another ship, and pass that information to other air traffic controllers so that they know that dock is now freed up.\n5. Confirm that the ships know where they're going, and that they are, in fact, going there.", "500" ], [ "And that they can, in fact, get there.\n5.) is where things become complicated; because things can go wrong on any of the other steps. Because most of the time, when you give a person a dock, they can get to that dock, or request a closer one. But emergencies, you run into issues of where they can dock in an emergency.\nIf, say, a stray micrometeorite destroys their engines, you might end up in a situation where they need to land, but specifically, can't land back at the dock they just left a few minutes ago because of their current momentum. If your lucky, you can find them another dock in short time - if you're unlucky, you get to prepare emergency recovery services for when they are \"Going to be in the Hudson\".\nWhich sort of gets to the core of why you wouldn't dedicate an A.I. to take on the initial steps of this - the Hudson River is not a runway, landing strip, or airplane docking port; your A.I. that tries to handle this is going to have an issue about this and be \"particular about it and make it a runway/dock.\".\nThese are rather stressful situations presumably, which is why it's great that those situations are usually rare, and the job is usually a button factory workplace job. You go into work everyday hoping that's the type of day it is; but you never know when it's going to be a \"Hudson\" day, so the docking station prepares for the case where it is, in fact, one of those days.", "500" ] ]

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[ [ "Tajik Parliament Plans to Monitor Citizens Who Visit ‘Undesirable’ Websites · Global Voices\nIndependence monument in Dushanbe, Tajikistan. Photo by <PERSON> via Flickr (CC BY-ND 2.0)\nSecurity services in Tajikistan will soon have the right to monitor citizens’ online activities, by keeping detailed records of SMS and mobile messages, social media comments, and anyone who visits “undesirable” websites.\nThis week, the parliamentarians passed legislation that grants the country's security services the right to monitor and control citizens’ online activities, as part of a set of amendments to existing criminal law.\nThese have not yet been made public, but local news website Asia Plus has obtained some details from experts and parliamentarians. According to the website, two special cyber security units in the Ministry of Internal Affairs will be responsible for following Tajiks online.\nLocal MP <PERSON> told Asia Plus that for an “inappropriate comment,” a commenter can be fined. Comments considered damaging to someone's personal honor or undermining national security can be punished with a jail term of two years or more. What exactly qualifies as an “undesirable website” or an “inappropriate comment” is not clear.\nA prominent supporter of the legislation is <PERSON>, who in addition to being the president's daughter, serves as his chief of staff and as a senator in the Majlisi Milli, the upper house of the country’s parliament.\nTajik MP <PERSON> first introduced the amendments and justified the call by claiming, without offering evidence, that more than 80% of Tajiks who have internet access visit “undesirable websites belonging to extremists and terroristic organizations.”\nInternet technology expert <PERSON> told RFERL's Tajik service that <PERSON>'s claim might have stemmed from a very basic misunderstanding. In one recent conference held in the capital Dushanbe, a speaker said that “80% of Tajik members of ISIS [the fundamentalist militant group that controls pockets of territory in Iraq, Syria and Afghanistan] have been recruited by others, including via the Internet.”\nThose are two very different statistics, but MP <PERSON> was quick to offer a solution to what he sees as an internet out of control.\nReacting to the news, Facebook users expressed concerns over how “undesirable websites” might be determined:\nБез опубликованного списка могут интерпретировать что угодно. Зайдешь на сайт, выйдешь.", "148" ], [ "А кто-то после тебя там напишет что-то новое а ты там был…\nWithout a public list [of websites] they can interpret [undesirable] however they want. You visit a site and leave it. But afterwards the website might publish something new, and you were there.\nThe legislation also represents a shift in strategy for the Tajik government, which has historically opted to censor controversial websites and services. Now, rather than preventing citizens from accessing online materials, they will use these sites as vehicles for monitoring citizens’ activities.\nIndeed, for several years, Tajikistan periodically blocked access to popular social media, such as Russian Odnoklassniki and VKontakte, Facebook, YouTube, and local top news websites. These sites were usually blocked around times of heightened political tension or public unrest, such as military clashes in some parts of country. YouTube was blocked for a week in 2013 after a video of President <PERSON> dancing at his son's wedding went viral.\nAfter a few weeks or months, access was typically restored amid international pressure. But in more recent years, all these websites were blocked wholesale, for no apparent or specific reason.\nThe government rarely admits that it orders web blocking, but internet service providers have repeatedly confirmed regular ‘verbal’ orders from authorities.\nThe constant lack of access to social and news platforms has led to widespread use of virtual private networks that have become the main means by which Tajik netizens access blocked websites, and especially social media.\nBut with the government's new legislation, this may change.", "148" ], [ "Going Postal: Tajikistan Stops DHL, UPS and Pony Express in Their Tracks · Global Voices\nPixabay image. OpenClipart-Vectors / 27454. CC0 Public Domain.\nTajikistan, a country with an atrocious state postal service, has shut down several international courier firms such as DHL, UPS, TNT, and Pony Express. The government says that the firms that have been working in the country for the bulk of its 25-year independence will now need licenses to operate.\nLast week the buildings of the companies in the capital Dushanbe were sealed off and their employees ordered to leave the premises, several local and international news agencies reported.\nThe move was the apparent brainchild of the Tajik Communication Service, an organisation that does more to inhibit communication than facilitate it. Mostly, the service headed by <PERSON> (formerly <PERSON>) is known for orders to block social media platforms. In 2012, <PERSON> blocked Facebook — which he accused of spreading “slander and lies” — and sent a barb in <PERSON> direction.\nDoes this Facebook have an owner or not? Could he come to Tajikistan? I would meet with him during my office hours.", "148" ], [ "If he doesn't have time, I could meet with one of his assistants.\nThat explains why Tajik Facebook user <PERSON> wrote ironically last week:\nВообще хозяин у этого DHL есть или нет? Он не может приехать в Таджикистан?\nDoes this DHL have an owner? Can’t he come to Tajikistan?\nMostly, international courier services have operated normally in Tajikistan, although DHL employees were accused of sending drugs to Russia ten years ago. The reason they are being targeted now may have more to do with rent-seeking behaviour increasing as the country's economy falters.\nPut simply, these courier services, which are too expensive for ordinary Tajiks but useful for international organisations, corporations and embassies, are a soft target. They can be shaken down without significantly angering the broader population.\nAnother, more regular target for the Communication Service is Internet Service Providers (ISPs), who are completely beholden to <PERSON>, a relative of Tajik President <PERSON> via marriage. One ploy to extract money out of the cash-cow ISPs is the Unified Electronic Communications Switching Center the government plans to build at their expense.\nAs Eurasianet reported last year:\nIn its latest effort to fasten its grip over the flow of information in and out of the country, the government has established an agency called the “Unified Electronic Communications Switching Center,” abbreviated as EKTs in Russian.\nIn crude terms, the system requires all traffic — be it from mobile phones or the Internet — to be filtered through a network gateway run by state-owned telecommunications company Tojiktelecom.\n“Implementation of the decree is obligatory for all domestic entities active in the electronic communications sector,” the decree states.\nThere are doubts, however, as to the extent to which the the centre will even exist, with many viewing it as an elaborate facade to secure payments from ISPs who have been unable to extract meaningful information about how it will operate. Earlier this year, the same website reported that Tajikistan's government was using other methods to extort cash from the same companies.\nA few months ago, all private dealers of mobile phone sim cards were shut down, emptying space for two new dealers rumored to be belong to <PERSON>'s son, who is also the all-powerful <PERSON>'s son-in-law.\nThere are rumours that the very same man now plans to open a new ISP. Only time will tell whether he will add a new private courier to his blossoming business empire.", "148" ], [ "Did Tajikistan’s ‘First Parrot’ Flee Its Gilded Cage? · Global Voices\nA pet African Grey Parrot on a wooden perch in a garden. Photo by <PERSON>. Creative commons.\nA princess’s beloved parrot left its cage and flew to its freedom. The distraught princess’s people scoured the city for the escaped parrot and announced a reward for anyone who found it.", "117" ], [ "No trace of the winged creature emerged.\nA fairytale set in the middle ages, or just another day in Tajikistan? The morning the story became known — via shares on social media rather than the town crier — many Tajiks felt as if they had woken up in a foreign country.\nOne social media user, <PERSON> encapsulated the confusion:\n: Аз сахар хезам, хама сухан оиди тути. Кадом тути?\nI woke up and saw that everyone talks about a parrot. What parrot?\nWhat parrot indeed? Only the gray and red, African-origin (Psittacus erithacus) parrot called Roma that belonged to the daughter of Tajikistan's officially titled Founder of Peace and National Unity, <PERSON> Nation, <PERSON>!\n<PERSON> is not just the Tajik president’s daughter but his chief of staff who is considered one of main political decision-makers in the country. But despite wielding the kind of powers that <PERSON> might only dream of, <PERSON>'s people were apparently unable to hold onto a parrot that wanted out, offering up an interesting metaphor for an authoritarian country dependent on cash transfers from migrants working abroad.\n<PERSON> wrote:\nЭта сладкая слова СВОБОДА…\nThat sweet word: FREEDOM.\nUp to half of working age males in Tajikistan abandon the impoverished country to seek work in Russia and other countries.\nThe saga of <PERSON>, which was not reported by any media outlets inside the country, also gave Tajik internet users cause to highlight the growing number of citizens from the country seeking refuge in Europe.\n<PERSON>:\nТути давно дар Аврупо ва панохандагии сиеси пурсидааст!))))\nThe parrot is already in Europe and asking for refugee status.\nOthers meanwhile hinted at the repressive measures sometimes taken by the country's government towards the relatives of political refugees:\nТутиро тамоми хешу авлодашонро заложникий гирифтанд\nAll relatives of the parrot have been taken hostage.\nA rumoured reward of 1,000 Tajik somonis (around $113) for anyone that found the parrot saw further sarcasm:\nШояд тутии суханчин бошад?) Хеле сирру накшахоро донад\nMaybe it was a talking parrot and knew of many secrets and plans?\nБубинед дустони гироми! Арзиши як паранда аз шаҳрванди Тоҷикистон чигуна баланд аст. Барои ҷустуҷуи як тути омода ҳастанд маблағ ҷудо кунанд ва тамоми вазоратҳову корхонаҳо думболи ин кор шаванд.", "148" ], [ "‘Singing the Tale of Our Pain’: Tajikistan’s Migration Phenomenon Finds a Home in Music · Global Voices\nScreenshot from <PERSON> – Yori Musofir (2015). Music Video uploaded onto YouTube January 3, 2016.\nIn jobless Tajikistan, leaving your loved ones behind to take up menial work in Russia is almost a rite of passage. Local pop music, in turn, has become an important medium to reflect on the social transformations triggered by the mass exodus of young men from the former Soviet country.\nНамехоҳам аз ватан дур, зиндагӣ мекунад маҷбур,\nМакун гиря модарҷонам, қисмати мо чӣ талху шӯр.\nАз ошиқам ҷудо кардӣ, дилам пур аз ғамҳо кардӣ,\nМаро тани танҳо кардӣ, ба дардҳо мубтало кардӣ,\nОҳ ғарибӣ!\nNo desire to leave homeland, but have to,\nDon’t cry, dear mother, our fate is that bitter.\nI am separated from friends, and love,\nMy heart full of sadness, I’m lonely and sick.\nTajikistan is home to more than eight million people.", "148" ], [ "It is estimated that more than half of all working age males seek jobs abroad, overwhelmingly in Russia.\nAccording to World Bank data, migrant remittances equate to a greater proportion of Tajikistan's economy (26.9%) than any other economy in the world, bar those of Central Asian neighbour Kyrgyzstan (30.4%) and Nepal (31.3%).\nThe factors pushing citizens away from the majority-Muslim country are manifold. It is the poorest of the 15 republics that gained independence from the former Soviet Union. Corruption is rampant and public services are in turmoil. For those able to find work, wages are low and often outpaced by inflation.\nҲар куҷо шодаму шодон, ба ёди Ватанам,\nҲар куҷо ташнаву ношод, ба ёди Ватанам\nWherever I am happy and joyful, I think of homeland,\nWherever I am thirsty and sad, I think of homeland.\nThis upbeat music video put together by the International Organisation for Migration and the Tajik government calls on migrants enjoying success abroad to contribute to their homeland's development.\nThe clip includes footage (from 2.50) of long-serving Tajik President <PERSON> meeting with compatriots in Moscow.\nThe reality of most migrants’ lives is far less colourful than the video above suggests.\nWorking conditions in Russia and other host countries are often poor, with corruption, racism and exploitation at the core of everyday life.\nOn average, more than one Tajik labour migrant returns home in a coffin every day.\nТеппае гӯри бародар, теппае гӯри падар,\nБайни он ду теппа бошад ҷойи як гӯри дигар.\nГар бимирам дар ғарибӣ, Тоҷикистонам баред\nFather’s grave on one side and brother’s on the other side,\nIs there space for one more grave?\nFind it! If I die in gharibi, take my body home, to Tajikistan!", "148" ], [ "Veto Viber? Tax Telegram? Such Are Tajikistan’s Tech Company Conundrums · Global Voices\nCartoon by <PERSON>.\nIn an attempt to stem a cash flow crisis, Tajikistan is taking up increasingly hostile postures towards digital communications companies.\nIn recent months, the government has made moves to monopolize the internet service provision and revoke licences for cheap IP-based call services. It has also been reported that restrictions are being placed on popular mobile messaging applications.\nThese changes all could make life costlier for users in Tajikistan, the poorest country to emerge from the Soviet breakup.\nAt the beginning of January 2018, the state Communications Service ordered local, privately-owned internet service providers (ISPs) to purchase internet infrastructure only from the state-owned company “Tojnet” (managed by the state's telecommunications monopolist “Tojiktelecom”) instead of buying it directly from neighbouring Kyrgyzstan, as was their custom.\nThis was made worse when on December 18, 2017 authorities revoked ISPs’ licenses to provide IP-based cheap call services through a protocol known as NGN (New Generation Network).\nAt the start of 2018, users reported problems making calls through call and messaging app Viber, and suspected that the government was blocking the app.\nAlthough state officials claimed that they took these measures in the interest of “national security” “because of extremists’ threats”, motivations for revoking NGN service and blocking Viber's audio and video call features appear to have been more economic than political. Both had become a thorn in the side of state-run Tojiktelecom, as they allowed millions of citizens with friends and relatives working abroad to keep in touch without using costly international calling services.\nOver a million Tajiks are migrant workers outside the country, mostly in Russia. If it weren't for apps like Viber, Tajiks would likely be using international phone lines to call their relatives, and thus generating revenue for Tojiktelecom, the government-run international exchange point for telephony. Or they would simply call home less often.\nMessaging apps face uncertain future\nWhile massive numbers of users complained Viber had become inaccessible at the beginning of the year, problems using the app later evaporated under mysterious circumstances.\nViber began working again some days ago, but its functionality has been inconsistent, with some users reporting that they are unable to make calls, while others say it is full functional. IMO, another popular messaging app, remains fully functional.\nCuriously, the news website Akhbor, claimed that the (perhaps only partial) revival of Viber was the result of an intervention by <PERSON>, the 30-year-old mayor of capital city Dushanbe, who is also the son of long-reigning autocrat <PERSON>.\nWhile the news report is seemingly based on the testimony of a single anonymous government source, the claim is believable.\nViewed as his 65-year-old father's most likely successor, <PERSON> has used social media and apps to boost his public profile in his new role, after prior stints in charge of the customs service and state anti-corruption agency.\nAccording to regional news website EurasiaNet.org:\nOnly three months ago [<PERSON>] ordered the creation of a channel on Viber through which the general public could get in touch with the city government, so he is hardly likely to want to see the app being squeezed out.\nCommunications as a cash cow\nFew major companies operate in Tajikistan.", "534" ], [ "The country of 8.5 million is largely agrarian and strongly dependent on cash transfers sent by migrants working in Russia, which have dropped as a result of the economic downturn there.\nThat has left telecom companies and Internet Service Providers (ISPs) among the most significant contributors to Tajikistan's state budget. And beyond taxes, the companies have made other contributions to the state coffers.\nAt the beginning of 2017, at least three large telecommunications companies, two of them Russian (Megafon and Beeline) and one European (Tcell), faced large fines for tax evasion, ranging from USD $17 million to $35 million. The companies took the case to a local court but lost their legal battles. The only locally-owned major telecom, Babilon-M, was fined around USD $55 million in 2014.\nTajikistan also expects global tech firms to line up and pay. At the end of 2017, media reported authorities were looking to tax Google, Alibaba Group, and Telegram.\nThe basis for the reports was a letter from the head of the local tax committee to the government of Tajikistan dated September 2017 but leaked in December 2017. In it, tax chief <PERSON> complained the Russian state budget had seen billions of rubles in income from Google, Apple, Alibaba, Amazon and others in 2017.", "704" ], [ "Six Tajik Mothers Who Rule the Roost on Facebook · Global Voices\nWoman on Facebook. Creative Commons picture.\nOn March 8 Tajikistan celebrates International Women’s Day, a holiday that remains extremely popular in the former Soviet republics, but that was re-branded in Tajikistan as Mothers’ Day.\nHistorically, the vast majority of Tajik mothers lived hard lives, living behind the veil in their homes for centuries before the Bolsheviks came to power, forcing them to unveil and go to work in the cotton fields.\nSince the country's independence in 1991, their lives have been defined by years of separation from their husbands and children, whose cash transfers from Russia make the country the most remittance-dependent in the world.\nBut today is their holiday and Global Voices is marking it by focusing on some of the most empowered and influential Tajik mothers, whose voices in society have been further amplified by <PERSON> invention, Facebook.\nThese women have been chosen not because of the followers they have amassed — there are spam accounts featuring attention-grabbing pictures of women that have amassed more — but because of their unique contributions to modern-day Tajikistan.\n1. Tireless Promoter of Tajik Culture – <PERSON>\nKnown Facebook ladies of Tajikistan: <PERSON>\nA former advisor to President <PERSON>, the mother of two sons, and the owner of her own successful consulting business, <PERSON> rose to popularity on Facebook as an active member of a dozen groups during what is increasingly being remembered as a “golden age of Facebook openness” in Tajikistan between 2011 and 2013.\nWith her extensive background in administering Facebook pages, <PERSON> created the “I Love Khujand” group on Facebook to gather more than 10,000 residents of the second biggest city in the country to help promote tourism and investment by stressing the city's cultural and historical influences.\nWith this in mind, if you find yourself staring at a widely shared Facebook post describing Tajik national dress in Russian or the story behind a national recipe or custom, you can fairly well assume that it emanated from <PERSON> or fellow culture-promoters affiliated to her.\n2. Queen of the Networks – <PERSON>\nKnown Facebook ladies of Tajikistan: <PERSON>\nMother to a son and a daughter, <PERSON> is the best-known lady across Tajik Facebook and owes this popularity in part to her genuine bilingualism. Whereas most Central Asians choose to post in either Russian or a local language, <PERSON> feels comfortable posting in both.\nDespite a life that involves supporting her children's schooling and extra-curricular activities, as well as her job's demands of frequent travel, she always finds time for Facebook.\nThat is because Facebook is a vital part of her brand.", "148" ], [ "The former journalist — Voice of America’s ex-correspondent in Tajikistan — was until recently the subject of a headhunting battle between giant foreign mobile companies trying to harness Facebook to boost their popularity in the market. A few months ago Russia's Megafon lost this battle to Sweden's TeliaSonera, for whom Komilzoda is now a senior communications specialist.\nIn addition to promoting her company and trying to reply to clients that bypass the local call center and turn to her for advice on Facebook, <PERSON> shares life moments and thoughts with her followers as well as informing them about what spa salon she goes to and which ski resort she uses for her winter breaks.\nPresumably, these businesses are also clients of this highly connected mother.\n3. Housewife Superstar – Pari Saidova\nKnown Facebook ladies of Tajikistan: <PERSON>\nPari in Persian means ‘Fairy’ and is synonymous with female beauty in Tajik language and literature. The 25-year-old model star of the Tajik show business <PERSON> is fully worthy of the name.\nUntil last autumn, widow <PERSON> sat at home and took care of her five children, a very normal situation in Tajikistan.\nNo one except relatives and neighbours would know any more about <PERSON>, if she hadn't decided to open an account on Facebook and post some pictures of herself to grab the attention of show business producers.\nUp to one thousand likes under each picture turned her into the most in-demand model for modelling shows and Tajik music clips.\n4. Business First – <PERSON>\nKnown Facebook ladies of Tajikistan: <PERSON>\n<PERSON>’s tailored groups and pages are the main place thousands of Tajik Facebookers go to keep updated on market innovations and technological change.", "148" ], [ "Here’s to <PERSON> and Four Other Tajikistan Sporting Success Stories You’ve Never Heard · Global Voices\n<PERSON>, hammer throw champion of the 2016 Olympic Games. Image widely shared among Tajiks on Facebook.\nAs Tajikistan prepares to welcome home its gold-winning Rio 2016 athlete <PERSON>, Global Voices reminisces over this and other sporting achievements the small, mountainous, Central Asian country has recorded over the course of its fraught 25-year independence.\n2016 – <PERSON>, first Olympic Gold\nIf you read Global Voices, you might already have heard of this one.\nHammer-thrower <PERSON> was a son of the civil war that raged in Tajikistan from 1992 to 1997 — his father was killed fighting in 1996 when he was only 15 — and his incredible victory at the Rio Olympics in some ways marked the long and difficult journey into peace that the country has made since the war's end.\nThe 34-year-old deputy chairman of the state Youth, Sport, and Tourism Committee of Tajikistan was the country's standard-bearer at the Games and its best chance of a podium finish, although few could have predicted he would upend all of his more fancied rivals to take gold.\nIn a rare move, the country's veteran President <PERSON> began his morning with a phone call to Dilshod to congratulate him, while municipal officials in several cities hung up huge banners bearing an image of <PERSON>’s smiling face with the country’s flag wrapped around his neck.\nTajikistan's opponents-in-exile meanwhile even ceased for a day an otherwise endless stream of criticism of the government to honour the achievement, as <PERSON>'s family home was mobbed by well-wishers.\nNowhere was the hubbub more visible than on Tajik sections of social media, where support has been building ever since to recognise <PERSON> as a National Hero of Tajikistan.\n2015 – FC Istiqlol reach the AFC Cup final\nFC “Istiqlol” after one of victories at the AFC Cup 2015.", "148" ], [ "The picture is from the official web-site of the FC “Istiqlol”\nOk, it's not the European Champions’ League, and, in fact, it's not even the Asian Champions’ League, but you can only excel in the tournaments you are allowed to enter, right?\nWhen the perennial national football champion of Tajikistan Istiqlol was drawn in an AFC Cup group with two teams that had graced the final of the tournament the year before, everyone was skeptical.\nIn the first game Istiqlol lost on home turf, but surprises came later with an unexpected series of victories over their better-fancied rivals, which enabled the country's top team to wind up first in the so-called “group of death”.\nExpectations increased as the team advanced through the knock-out stages of the tournament — the second most prestigious professional tournament in Asian club football — culminating in the final which again was played on home soil.\nUnfortunately, the referee cancelled all three goals scored by Istiqlol during the game, allowing Malaysian side <PERSON> to leave the Central Asian country with the cup.\nDespite the perceived injustice of the game, the country was grateful to its footballers for the positive emotions that came with every victory over stronger and better-known teams.\n2012 – <PERSON>, first female Olympic medal\n<PERSON> during the awarding ceremony wore Tajik national clothe. The picture is taken from girlboxing.org\nTajikistan was awash with emotion when a tiny girl, who as a teenager had brought the body of her dead father back to Tajikistan from their home in Moscow, won bronze at the 2012 London Olympics.\n<PERSON>’s medal in the lightweight boxing was not the first Tajikistan had won at the Olympics, but it was the first won by a female representative of any Persian-speaking country (Iran, Afghanistan, or Tajikistan).\nTo call 2012 an incredibly successful year for a 20-year-old girl hailing from a poor family of economic migrants would be an understatement.\nIn addition to the Olympics, <PERSON> also took medals at the World and Asian championships, winning praise at home and earning several flats as gifts from the impoverished state.\nThe same year, as Global Voices reported, <PERSON> got married and briefly hung up her gloves to have her first child.\n“I love the sport,” she told journalists at the time. “But family is more important to me.", "910" ], [ "Uzbekistan: Playing Politics on Facebook · Global Voices\nFacebook seems to have started playing an important role in Uzbek politics. However, so far it is more a tool for playing games with fake accounts, rather than an instrument of civil protests.\nPlanted suicide story?\nOn 6 December, 2011, Radio Free Europe/Radio Liberty reported on a suicide committed by a young woman in the western Uzbek city of Andijan. After coming home on vacation, <PERSON>, a 32-year-old university student in Germany, was allegedly interrogated by police for four days.\nAccording to the Uzbek NGO Human Rights Alliance, <PERSON> was beaten at the police station and forced to write statements against <PERSON>, the self-exiled leader of the opposition People's Movement of Uzbekistan (PMU). The movement was formed in May 2011 from a number of foreign-based Uzbek opposition movements and rights organizations and stated its goal as being the downfall of President <PERSON>'s regime.\nFacebook profile picture of <PERSON>, which is actually a photo of turkish model <PERSON>\nAccording to her Facebook account, <PERSON> was a supporter of this movement, and a person with the name <PERSON> was among her Facebook friends. That was the reason, some netizens believe, that the young woman came to attention of the Uzbek authorities. However, the PMU website has stated [uz] that <PERSON> was never a member of the opposition movement.\nIt’s worth mentioning that Interior Ministry officials in Andijan gave no comment. <PERSON>’s relatives (according to her Facebook profile she is married, and Human Rights Alliance mentioned <PERSON>’s sister who allegedly found her suicide note) have also kept silent.\nThe story became more perplexing when two days later, on 8 December, the opposition site Uzmetronom.com published [ru] an article with the results of a journalistic investigation, carried out by the website. The author of the article, who remained anonymous, concluded that the entire story is provocation prepared by <PERSON> to destabilize Uzbek society and gain international attention.\nThe story has attracted the attention of netizens.", "289" ], [ "One of them comments on the idea that it may have been planted by members of the Uzbek opposition in order to smear the Uzbek government. Other suggest that it was made up by the national security services to show people the dangers of supporting the opposition movement.\nIt still remains unclear who could benefit from the made-up story and probably this will not be known. <PERSON> from Registan.net sums up:\n[…] it reveals a great deal of how rumor operates on the Uzbek political internet. The assumption that all information is unreliable, and all sources biased, has had the perverse effect of ensuring that all rumor is taken seriously.\nPrime Minister’s fake Facebook account\nAnother topic that has sparked controversy among Uzbek bloggers was the Facebook account of Uzbekistan’s Prime-Minister <PERSON>. His Facebook page, created early in May this year, has about 2,000 friends and identifies him as a 100% Muslim with conservative political views, interested in women and married.\n<PERSON> from Eurasianet.org comments:\n[…] you can see that <PERSON> is inspired by <PERSON>, <PERSON>, <PERSON>, <PERSON> and […] <PERSON>.\nHis gmail address is provided, so write and ask any questions! Don't expect any cat or dog photos, however.\nOthers wonder why the Prime Minister doesn’t have a personal page on Uzbekistan’s local social network Muloqot.uz and speculate that the main goal of his Facebook page is to attract a Western audience.\nHowever, after a semi-official statement from the Prime Minister's “offline office” about contacting the Facebook administration with a request to delete the page, it became clear that the account is not authentic.\nDangers of being too public\nThis is not the first time that high-ranking Uzbek public figures’ names have been used for suspicious accounts in social networks. Early this May the blogosphere discussed two Twitter accounts which were affiliated with President <PERSON>’s daughter <PERSON>. The first one, @GuliKarimova, does not exist anymore. However the second one, @GulnaraKarimova [ru], is active and has over 1,800 followers\nAs we see, social networks in Uzbekistan are getting used in some games with political background. Therefore <PERSON> from Eurasianet.org warns:\n[…] arguments about the dangers of being too public with one's affiliations on public social networking sites remain in force.", "148" ] ]

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[ [ "How can I prevent fleas on my cat when I work in a storage unit? I currently have her on revolution plus.\nHi I work at a storage unit full time. Just recently I discovered fleas/flea dirt on my kitten and I treated her with revolution plus ever since. I don't know if I got it from my coworker who a said his bf had pets that had fleas or I got them from work.", "311" ], [ "But I know storage units can be a big risk for fleas. I currently bag my clothes and change in the car to new clothes everytime I enter the house as well as change shoes and shower before enteracting with my cat. What further steps can I take to stop her from getting fleas as far as what im don't right now.", "601" ], [ "My kitten got fleas help! :(\nHi, I have a kitten that's 5 and a half months old now. I noticed a flea in my bedroom where she stays with me all the time and I combed her out and saw flea dirt :( so I went to the vet to get some topical flea treatment. I put one dose on her and will continue to be putting it on her monthly.", "664" ], [ "My room is all carpet and I've been vacuuming as much as I could with my full time job I'm exhausted. I want to call pest control bc that would be my last resort. I also bought some food grade diemtoeous earth but don't know the best way to use it. Any times from anyone?", "502" ], [ "Questions About Fighting Fleas\nSo, I am dealing with fleas for the first time. I have read up on combatting them, but still have a couple specific questions I haven't found answers to. (Context: We have one dog, about to begin treatment. No carpet. The infestation seems to be in its early stages.)\n1. After I do a deep clean, can I block off areas of the house to avoid daily cleaning? .", "661" ], [ "I spend a lot of time at work, and my housemate does not have the mobility to reasonably get downstairs. If I clean everything and then close the door such that the dog can't get down there and shed eggs, can I reduce the frequency of cleaning? By how much? If not just closing the door, would a draft stopper work?\n2. Do I have to clean cloth that does not touch the floor and pets do not have access to? . I know that fleas can jump and climb, but do I have to clean things such as the felt on a pool table? From what I understand, fleas tend to lay eggs on an animal that then shed off. Do I need to worry about fleas going out of their way to lay eggs on the pool table? Placemats on the dinner table? Fabric posters on the wall?\nAny advice would be greatly appreciated. I don't want to cut any corners, but I also don't want to be scrambling to complete tasks I don't necessarily have to. Thanks for reading this far.", "661" ], [ "Cat's allergy test results\nI couldn't take it anymore and finally ordered a blood panel. I was hoping someone else who's been down this road would know what I can do to mitigate her reactions.\nShe overgrooms mostly on her belly and back legs so it could be something she sits on like dust or cotton. And sometimes I burn candles which makes me think of her high positive to pine. Could be in other household items as well.", "664" ], [ "I also plan on staying on top of dusting and vacuuming. Does the dust in litter count as an allergin?\nAs far as food allergies, they gave me a list of food from different vendors she can have. For dry kibble, she can have Hills pet nutrition, Natura, Royal Cain, Taste of the wild, Wellness, and Zignature. Does anyone have strong opinions on any of these?\nAny tips or advice are much appreciated! Thanks!", "747" ], [ "Can I leave my cats alone for 2 days?\nSorry, this has probably been asked before but I’ve been back and forth with moving houses and im currently stuck. I left my 12 cats yesterday around 3:30pm after I fed them their usual 2 and a half cans of wet food. before I left I also filled all 12 bowls with kibbles.", "176" ], [ "Water supply is ample, they have 2 pails to drink on, and 2 tubs filled with water along with another small container with water as well. Planning to go back tomorrow. Would they be fine ?", "661" ], [ "<PERSON>\nHey everyone, I’m really embarrassed to post this but hoping maybe someone else will have more insight as to what we’re missing or doing wrong? About a week ago we noticed fleas in our basement. We’ve bombed it and it seems the problem has spread to our upstairs from even going down there and coming back up with a few fleas on us. We have 2 dogs, 5 cats, 2 ferrets, and a multitude of stray cats outside all TNR. We take pride in our animal husbandry, 2 dogs and 5 cats all have Seresto collars placed on in march, not cheap. The ferrets get ferret advantage solution, as well as the TNR cats all get advantage. This is a really hefty bill and they ALL have fleas this week from this problem in our basement (the animals cannot access the basement.) We are vacuuming multiple times daily, steaming floors with tile, stripping dog beds and couches and washing every few days.", "661" ], [ "I’m kind of understanding why people think homes with multiple pets are filthy, no matter how much we clean it seems this is a bigger problem than originally thought. Will their flea solutions kill the fleas or is this going to stay on them? I’m going to flea powder our carpets and remove the animals from the home for the day. Do we have to buckle down and call an exterminator for this? Sorry if formatting is incorrect I’m on mobile. Thanks for reading. TLDR; animals in home and outside all have the best flea medication, fleas started in our basement terrorizing them and our home upstairs. What else can we do?", "661" ], [ "Animal pee smell.. help!!!\nSo I have a cat about 5 years old and a 5 month old puppy. Potty training has been difficult but we are working on it. I live in an apartment so it is mostly carpeted.", "833" ], [ "Although cleaning after every accident, I noticed some smell in my room. So I bought a small shampoo vac. Overall the smell in my room was WAY better but I went into my bathroom and still smelled it? I can’t tell if it’s cat or dog pee smell. I just cleaned the other day and completely refreshed the litter box (in my bathroom). I’m not sure where this smell is coming from or why it’s lingering but it was never this bad when I just had my cat.\nThoughts??", "311" ], [ "Am I too late to vaccinate my cat?\n6 months ago, I found a kitten near trash dumpster. I gave him some food and he started to follow me back so I took him in. I am not a cat person and I was in no way financially fit to even vaccinate that kitten.", "176" ], [ "I just managed to skip my lunch few times a week to get his cat food and litter. Infact, I hid him from landlord because I couldn’t pay for him. I did post on facebook so someone could adopt him but I haven’t had any", "940" ] ]

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[ [ "Use Paint Washes to Help Details Stand Out in Clay\nIntroduction: Use Paint Washes to Help Details Stand Out in Clay\nIf you only work in polymer or air dry clay and are not a paint artist, you might not know what a wash is, BUT YOU SHOULD.\nWhy? Because a paint wash can really bring depth to your creation. It is a well-known fact in the miniature game figures world that a black wash is the easiest way to bring out detail on small mini figures. You can use black washes, too, and I am going to show you how important they can be.\nSupplies\n1. Acrylic paint in black or dark browns (of course it depends on your sculpture what color you want to use, but dark colors work best)\n2. Water\n3. Paint brush\n4. Paper towels or a soft cloth\nFigures that have already been sculpted/painted ( I have a stylized leaf and a tiny <PERSON> head I made while doodling around one day).\nWorkspace.\nStep 1: The Figures\nHere are the two figures I am using to show this method. One is a simple piece, a green leaf, and we will be using the first technique with it. The other piece, the Gandalf head, has many more tiny lines and details, and we will be using the second technique for it.\nStep 2: Technique #1\nI paint the clay, making sure the paint goes into the details. Then I wait until the paint gets mostly dry.\nWith a soft cloth or paper towel, I go over the surface of the piece, just enough to take off the paint on the raised surfaces. This leaves the details filled in dark.\nIf the paint doesn't want to come off as much as you want, wet the paper towel a little bit and then wipe off more paint in the same way as before. Do this until you have taken off as much paint as you want.\nThen I leave the piece to dry fully. I can do the wash again later if I decide I need to.\n*TIP: if you are using air dry clay, you will want to varnish your piece at least one coat before doing this so you don't damage the clay.\nStep 3: Technique #2\nThis is the method to use for pieces with more details.\nYou want to thin the paint a little bit with water so that it flows better to fill small details.\nI just add water carefully a tiny bit at a time.", "994" ], [ "I have found that super thin is actually not desirable, but neither is straight out of the bottle. Shoot for somewhere in the middle. You can always add more water, but you can't subtract it!\nOnce your paint is the thickness you want, you are ready to start painting.\nStep 4: Painting the Wash\nWith the brush, apply paint over the area you want the details to show up on. Make sure it goes into the details and doesn't miss them. I am starting with <PERSON>'s hat.\nOnce the whole hat is covered, I use the damp paper towel to dab off excess paint. When I am happy with the amount of paint, I continue on to another piece of the sculpture.\nA lot of the time I paint some on, dab some off, paint some on, dab some off until I think it looks pretty good.\nStep 5: Comparison\nThese are the same pieces, just one doesn't have a wash and the other one does.\nSee the difference?\nIt is a pretty good way to make details pop. It makes your sculpture much more eye catching and detailed than without.\nI hope this was helpful and you can use this information to better your clay.\nStep 6: More Examples\nHere are two more examples. The first, the rose, is a flat piece similar to the leaf.\nThe second is a more detailed piece. Once again, it is <PERSON>. This <PERSON> was a Christmas present for someone. He was the first tiny person I made that I tried to make detailed. The wash helped bring out the tiny pieces of his face and give his robes much more drama.\nI hope this technique helps you in your clay projects. Go clay today!", "994" ], [ "Polymer Clay Lion Fountain With Resin or Hot Glue\nIntroduction: Polymer Clay Lion Fountain With Resin or Hot Glue\nHello!\nI'm back again with another sculpting project!\nThis is actually very simple to make, and turned out looking awesome!\nThe design for the resin fountain was kind of Narnian inspired. I have always loved that series and have made a few other Narnian inspired creations.\nDon't have any resin?\nNo problem! I will show you how to make this fountain with hot glue too! Hot glue is a lot more adorable and easier to get your hands on. It also works very well for making little clay fountains!\nLet's get started!\nSupplies\n* Polymer clay of your choice >>> This is what I am using\n* Sculpting tools >>> These are some that I use\n* Acrilic paints\n* Paint brushes\n* Small container of water (To rinse your brush)\nFor the resin\n* Resin The resin I am using is \"Amazing Clear Cast Resin\" You can get this here\n* Disposable rubber gloves\n* Tooth pick\n* Hot water in a bowl (optional)\n* A small container you can throw away\n* Hot glue gun with hot glue\nStep 1: The Body of the Fountain\nLet's start by rolling out your clay but leave it kind of thick so it will be less brittle once baked.\nThen cut out a rectangle shape and cut the corners off on one side. It should look like the 3rd pic above.\nNow cut a thin strip of clay and wrap it around the bottom of the rectangle, and gently blend the sides in.Then roll out another sheet of clay and cut to shape, and gently blend in, again.I then cut another long thin strip to go around the top of your fountain.\nThis is the body of your fountain!\nStep 2: Finishing the Body of the Fountain\nI also then drew a brick pattern on the bottom of the fountain, and textured it with an old toothbrush.\nThen I added a strip of clay around the rim of the bottom of the fountain. Also, I drew a brick pattern and textured with the toothbrush.\nI wanted it to have an old look so I took one of my tools and put cracks in the brick where I thought it looked good. I also did the brick texture on the edge around the top of the fountain, and textured the back of the fountain.\nThen for a bit of design, I added some random shapes and stacked them on the top of the fountain, and once again, textured them.\nStep 3: Adding the Lions Face\nI decided to add a lions face to mine, you don't have to.", "95" ], [ "It just felt very Narnian like and that was what I was going for.\nTo start the mouth of the lion, I took 2 U shapes of clay and placed them towards the top of the fountain. Make sure there is plenty of room so you can get the resin in the mouth.\nI then added a forehead and got to work on the mane.\nThe way that I usually make a lion's mane, is that I take a ball of clay, roll one end to a point, and cut. Then I just position the hair wherever I like.\nJust keep doing this until you are happy with the mane. Also don't forget to add little ears by making little balls and pressing them on the sides of the lions head.\nThen add the facial details, like eyes nose and mouth, and your done with the face.\nI for some reason thought it was a good idea to put green clay as the ivy even though I knew I had to paint over it. It was pretty pointless, but at least you can see it in the picture better than if it wasn't green!\nAnyway, I just put little snakes of the green clay and put them here and there and textured them with one of my tools.\nNow you can bake this according to your package instructions!\nStep 4: Let's Paint!\nTime for one of my favorite parts...Painting!\nStart by painting the whole thing black.\nI then dry brushed dark grey all over the fountain then went in with a lighter grey and dry brushed again.\nDry brushing is where you go over a darker color with a lighter color when there is barely any paint on the brush. This leaves the dark paint in the crevices and the lighter color on top.\nAlso once you are finished painting the grey on, why not go in with a nice dark green and paint over the ivy.\nStep 5: Resin Part 1\nIf you don't have resin, just skip this step and go on to step number 7. That is where I show you how to do this with hot glue.\nI felt that this step was too long, so I put it in 2 parts.", "987" ], [ "Indigo Bunting Necklace\nIntroduction: Indigo Bunting Necklace\nSo, for the Rainbow Contest, I decided to go after that strange, illusive color, Indigo. For me, what pops in my head right away, is the cute little Indigo Bunting. I have seen a lot more of them this year than I have before. They tend to just look like bright flashes of color as they dart past, hiding in the weeds.\nInstead of just portraying the well-known, flashy male, I decided to put him together with his female counterpart. I decided that a lovely little nest scene was a good way to show them. It is also a good way to educate people on what the two of them look like; a stark contrast of one another, the male bright indigo and the female in a drab brown of concealment.\nCome along and create this cute necklace!\nSupplies\n1. Clay in brown and indigo (or as close as you can get - we will add some colored pastel and mica powder to help his bright coloring).\n2. Clay tools (roller, knife, and stylus or needle tool)\n3. Work space\n4. Tiny ball tool (also known as mandala tools or nail dotters)\n5. Small soft brush for using with pastels and paint\n6. Pastels in various shades of brown. Also you should add in green, blue and purple, and a grey if you have it (which I don't).\n7. Acrylic paint in black and grey (Grey not pictured)\n8. OPTIONAL: Mica powder in purple and blue. I think this just adds to his shimmery shininess, but you could also just paint him with metallic purple and blue paint.\n9. Necklace chain with wide links\n10. Two large jump rings\n11. Set of round nose pliers\nStep 1: Sculpt the Nest\nWe will begin with the nest.\nRoll out the brown clay. Don't make it too thick or too thin. With the knife tool or the stylus, sketch a bowl shape on the flattened clay. Trim this out with the knife tool. Set this aside.\nCut out two thin strips of clay from the leftovers.", "95" ], [ "These will be the limbs that the nest sits in between.\nWith the stylus tool, scratch lines into the two limbs, making them resemble the bark of a tree. If you have any silicone stencils that are wood-like this would be a cool time to use them. Just make lines until you are satisfied. Vary the lines in thickness, thinness, and length to make them look more natural. I also used the knife to cut the end of one of the branches and make a small broken branch piece sticking out from it.\nStick the ends of the two limbs together so they make a \"v\" shape. Place the bowl in the middle of the \"v\". Make sure it is tightly adhered.\nStep 2: Nest Details\nWith the stylus tool, scratch and swirl the needle around to make a rough, fiber-like appearance. Their nests are made of twigs, but I have yet to come up with an easy technique to make small twigs that I am satisfied with. This is what I do right now, maybe someday I will figure it out.\nAt the ends of the branch limbs, poke holes all the way through the clay. These are for the jump rings. Make them larger than you think they actually need to be.\nNow get out the brown, green, and grey pastels. With the small brush, dust the branch limbs first with various browns. I made mine pretty dark. Then dust the nest with a variety of the brown, green, and grey. You don't want to make it as dark as the limbs because then it won't stand out.\nSet the nest aside.\nStep 3: Female Bunting\nWith the left over brown clay, roll it out. Sketch a bird with a crest on the flattened clay. I advise looking up images of the Indigo Buntings to help you with this. Indigo Buntings are a member of the Cardinal family, but I have noticed in most photos I have looked at the female's crest is much more apparent than that of the male. They have fat beaks like finches (and Cardinals, duh :).\nTrim out the bird. She doesn't have to be a whole bird; only the top half because she will be sitting on the nest. With the stylus tool, sculpt the little details, like the eye, the beak, and various feathers. I just make pokes and scratches to indicate the feathers.\nColor the bird with pastel. This did not turn out like I liked it, so I added some grey paint later on, so you could just skip this and simply paint her if you wanted.", "879" ], [ "Ocean in a Bottle With Moon Jellyfish Pendant\nIntroduction: Ocean in a Bottle With Moon Jellyfish Pendant\nThis tiny piece of ocean will remind you of the beauty in nature; with a Moon Jellyfish gliding through the blue waves.\nI had meant to do this project for the Rainbow Contest, but I didn't get around to it. This is a simple but beautiful piece of jewelry, but it can also double as a stress reliever. Shaking the jar to produce bubbles and then watching them dissipate can help bring your mind off of your worries. I added an almost transparent Moon Jellyfish to give the jar a focal point and to give you an oceanic friend.\nSupplies\n1. Small glass jar with cork\n2. Water\n3. Baby oil\n4. Blue food coloring\n5. Small jars for mixing\n6. Eye dropper or syringe\n7. Shells small enough to fit in your jar\n8. Eye Pin\n9. A small cured piece of clear silicone OR a transparent rubber pencil grip (it can be a transparent color).\n10. Small scissors such as nail or embroidery scissors\n11. A small needle\n12. Invisible sewing thread OR fishing line\n13. Tacky glue or another strong glue.\n14. Chain necklace or other necklace material for\nStep 1: Making the Ocean\nTo make the ocean, pour a little bit of water into the mixing jar. Add a drop of blue food coloring. Make sure it is thoroughly mixed. Add more water to make the ocean a lighter blue (this is personal preference - it doesn't affect the outcome).\nWith the eyedropper or syringe, drop some of the blue water in the jar, about a third of the way up (this is also preference).\nRinse out the mixing jar. Pour a little of the baby oil in it. With the eye dropper (rinsing isn't necessary), add baby oil almost to the curve of the bottle or where the bottom of the cork will be.\nNow drop in two or three small shells.", "95" ], [ "I am using shells that came from my one trip to the beach so it will remind me of how wonderful it was.\nTake the cork and push an eye pin into the top of the cork. This will be the hook for the necklace.\nThe ocean habitat is ready for the jellyfish.\nStep 2: Making the Moon Jellyfish\nSo, cured clear silicone is the most interesting ingredient in this project. I am using a bit off of a failed silicone mold, but I realize not everyone makes their own silicone molds.\nHowever, many people use silicone for a variety of things. Even if you don't use silicone, you probably know someone who does. They could probably help you out, especially since you only need less than a marbles amount. If you can't find any, silicone tubes run around four to five dollars.\nHowever, another thing you could use are pencil grips. They come in many colors and are rubbery just like the silicone. Dollar stores will carry them sometimes. I am using silicone, but the method will be the same.\nTaking a tiny piece of silicone, I begin to cut it into a bell/rounded shape. This will be the bell of the jellyfish. I am making it about the size of a large sewing pin. Try to make the sides slope into a bell shape.\nOnce you are happy with the shape, cut a very long piece of the invisible thread. Thread the needle, but don't tie it off. Instead, pass the thread through the needle until the needle is about halfway along the length of the thread.\nPoke the needle through the bottom of the jellyfish. Pull it through until you have the untied ends of thread hanging out the bottom. These are the jellyfish tentacles. Don't pull the needle all the way through. Instead, poke the needle back through the top of the jellyfish NEAR the spot that it came out of, and pull the thread until it is flush to the top of the head. Don't keep pulling or you will accidentally pull the thread all the way out. Turn the needle around and poke it back up through the bottom of the jellyfish, stopping pulling when you have a small loop of thread not pulled through that will match the original two tentacles.\nDo those steps over and over until you have has many tentacles as you want (remember, except for the first two tentacles, every loop of thread is TWO tentacles. Don't overload it).\nEnd with the needle coming up out of the top of the jellyfish. The jellyfish is almost finished!\nWe saw a little jellyfish that had washed up on the beach while I was there, but that was the only one we saw. It was interesting, though, for someone who had never been to the beach to get to see a jellyfish.", "879" ], [ "Enlarging an Image Using a Grid\nIntroduction: Enlarging an Image Using a Grid\nAny home brewers out there?\nI am the king on mediocre home brewing and I'm going to show you how I enlarged one of my beer labels using a simple grid method.\nSupplies\nMaterials\n-Print out the image to enlarge\n-Scissors\n-Boxcutter\n-Ruler\n-Pencil\n-Red marker\n-Black marker\n-Paint\n-Paint brushes\n-Top coat\nTools\n-Jigsaw\n-Orbital sander\nMolding\n-Silicone molds\n-Polymer clay\n-Wood glue\nGold leaf\n-Gold leaf\n-Gilding glue\nStep 1: Draw the Grids\nYou totally remember the \"grid method\" from elementary school, but it basically involves drawing a grid over a reference picture, and then drawing a grid of equal or larger ratio on something else. Once the grids are finished, you draw the image on the new canvas focusing only on one square at a time.\nI doubled my image. I drew a 3x3cm grid on the printout of the beer label and made a 6x6cm grid on a piece of plywood.\n*You'll need to draw the exact same number of lines on the canvas as you did on your reference picture, and that in both cases, the lines must be equally spaced apart.\nIt's super easy and the best part is this is a low-tech, kid friendly way to draw any picture you like.\n*To help yourself focus on a square, use a boxcutter to cut out a matching square in a sheet of paper.\nStep 2: Cutting\nI used a jigsaw to cut out the oval and then I sanded it down.\nStep 3: Clay Moldings\nCreating polymer clay molding is easy!\n-Press polymer clay into the molding, filling every nook and cranny and keeping the top as level as possible\n-Paint a layer of PVA glue, epoxy resin, or gorilla glue onto the surface of where the mold is going.\n-Gently pull the clay out of the silicone mold. Don't wait for the clay to dry.\n-Paint the same glue on the back of the clay you just pulled out, and then gently press it onto the surface.\n-Let it dry for 24 hours.\n*You don't need to paint the surface first. I did, because I was trying to figure out my colors.\nStep 4: Drawing, Painting and More Molds\nI drew the image onto the wood going square by square.\nI started with the oval, painted it and continued on with the banner and \"Pilsner\" font. It was a little time consuming and I made a couple adjustments to the \"Pilsner,\" because it was too straight on the printout.\nStep 5: More Font\nI thought I could pressure engrave the font to where it would show up under a coat of paint.", "74" ], [ "NOPE! I wish I used a dremel tool. A few letters showed through, but I needed to draw arches and measure spaces since the grid was painted over. I also wish I didn't use chalk paint! Dang it! I mean, I really like how it looks, but it would probably look nicer without that chalk paint texture.\nStep 6: Gold Leaf\nFor gold leaf.\n-Brush on gilding glue and wait for it to become tacky. About 20 minutes.\n-Apply the gold leaf by placing it over the glue.\n-Remove the unused leaf by smoothing the wrinkles with your finger or a small paint brush.\n*The glue must be tacky or else the gold leaf is tough to apply. It'll slip around and get stuck to your fingers and brush.\n*Gold leaf gets everywhere too! Really....everywhere! It breaks down into little gold specks while you smooth, so keep cleanup supplies nearby and turn off the ceiling fan.\nStep 7: Finished!\nTop coat and hang!\nI'm starting to like the chalk paint texture now too. This was a really fun project and took me back to elementary school.", "959" ], [ "<PERSON>: An Island at Your Fingertip\nDioramas are great, but they can take up quite a bit of space. This lovely model, fits into a box, allowing for easier storage and protection from dust. This one is quite beginner-friendly, and I encourage you all to try it! For more inspiration, or perhaps you would like to own one without the hassle of making it, hop on over to @funsizescenery on insta.\nI do apologize for spelling and grammar mistakes in advance.\nSupplies\nFor this project you will need:\n* Xps foam or insolation foam\n* Plaster of Paris\n* Sand\n* Paint\n* Gesso\n* Glue\n* Fine grass flocking\nSome tools that come in handy are:\n* A sharp exacto knife\n* toothpicks\n* sandpaper\n* paint pallet\n* paint brushes of varying sizes\nStep 1: Sketch\nFirst sketch out your island on your piece of foam. Note where you have different terrain or varying elevation. Create a border of about 1/2 a centimetre away from your island to leave space for any errors\nStep 2: Cut Away Your Shape\nCut straight down along your border, as far as your knife allows you. A foam cutter can make this a lot easier. Next, cut diagonally outwards along your actual island border. Keep cutting away at the layers until you have your island free from the giant block of foam.\nStep 3: Cut Out Your Mountains\nNow that you have your island shape, you need to cut out your terrain. I have three main elevations, which are marked out on the side. as seen in the first photo. I follow the same steps outlined in the previous one to carve out my terrain.\nStep 4: Trust the Process\nFirst buff out hills and flats using sandpaper. Using a toothpick to chip away at small pieces, you can create rocky terrain.", "110" ], [ "Once satisfied, use plaster of pairs to coat each and every nook and cranny. you can use a paintbrush or a piece of foam to texture the plaster further. Coat the piece in sand to give it texture, as there is rarely anything truly flat in nature. If the plaster is too dry for sand to adhere, wait for it to set and coat the piece in glue first. Shake off the excess sand and get ready for painting!\nStep 5: Painting!\nThis is a smaller Island I made to match, first I paint grey for the cliffs and brown for dirt or grassy areas. Next, I drybrush with different shades until I am satisfied with the outcome. I recommend making a small island to try out techniques on as it doesn't take much extra effort.\nStep 6: What My Main Island Looks Like\nThis is what my main island looks like throughout my process\nStep 7: All Done Painting\nPainting complete for all my islands\nStep 8: Grass\nSprinkle grass flocking over hilly areas to give the piece some green\nStep 9: Houses and Details\nFirst, cut out tiny squares for houses. Next paint each block. Using a mixture of plaster, paint and glue (I colored mine black) Dab it onto the block with a toothpick. Smooth out the roof to your desired shape and voila!\nStep 10: Basic Island Complete\nIf you have no water features, this is where you can call it a day!\nStep 11: The Box\nI had a wooden box that I bought from a local dollar store. I cut my islands to fit into the box and arranged them till I was satisfied.\nStep 12: Adding Water\nFirst, to add some sense of depth, paint the bottom of the box blue, as well as the slopes of your islands. Next mix a batch of epoxy casting resin to the manufacturer's specifications. Pour it in carefully and allow to cure for 24 hours\nStep 13: Done\nVoila, here is an island in a box!", "706" ], [ "Howl's Moving Castle Earrings- Studio Ghibli\nIntroduction: Howl's Moving Castle Earrings- Studio Ghibli\nHowl's Moving Castle is one of my favorite Studio Ghibli movies. I find it inspiring.\nOne of the most sought-after pieces of Studio Ghibli jewelry is Howl's jewelry set. They sparkle like magic and are pretty pieces in themselves without having belonged to a handsome wizard. Today I am going to show you how to make your own Howl's Moving Castle earrings. I will be publishing Instructables on the necklace and ring as well.\nSupplies\nEarrings:\n1. Clay in green\n2. Eyepins\n3. Gold hook earrings\n4. Two small glass red seed beads\n5. Wire in 24 gauge\n6. Pliers\n7. Green pastel\n8. Knife or toothpick to scrape and mix pastel\n9. Soft brush\n10. Triple Thick (or TLS for polymer clay)\nStep 1: Sculpt Teardrop Shapes\nWith the green clay, roll it between your fingers, making one end smaller than the other, to make a teardrop shape. Insert an eye pin at the top of the tear drop. Make two. They should be about as long as a quarter is from side to side.", "95" ], [ "Bake or leave to dry.\nStep 2: Adding Red Gems\nGet out the gold earring hooks, piece of wire, and the glass red seed bead. With the round nosed pliers, curl one end of the wire piece into a loop. Slide the red bead onto the wire. The loop will stop it from coming off at the end.\nTake the round nosed pliers and curl a second loop on top. You will probably have to remove your pliers and pinch it closed. Now the bead should be trapped by the two loops.\nOpen the loop on the earring hook by twisting the loop sideways where it meets. Don't pull it open. Slide on of the loops on the piece of wire onto the loop on the hook, then twist the hook closed, trapping the bead's wire loop on the hook. Do the same for both pieces.\n*If you had gold wire it would be more accurate, but I didn't have any, so I had to go with silver.\nStep 3: Attach Earrings\nGet out the dried/baked tear drop shapes. Open the loop on the eye pin on the tear drop shape. Hook it to the end loop on the bead wire, making it hang from the bottom. Close the eye pin loop.\nStep 4: Triple Thick Varnishing\nTo give them a bit of a luminescent appearance, I will be varnishing them with Triple Thick mixed with green pastel. I chose a darker shade of green pastel so that they could look like they \"glowed\" from within.\nScrap off the pastel stick into a powder. Mix this powder with a bit of Triple Thick varnish. Continue mixing until you get an even color.\nWith a brush, apply the colored Triple Thick to the teardrop shapes. Be careful not to overwork it; you can go back and add another coat later, but if you keep brushing what you have applied it will become lumpy.\nI applied three coats in total.\nStep 5: The Earrings of <PERSON>\nAnd there you have it! You have these magical earrings. You can sport your Studio Ghibli style without screaming, \"I love Studio Ghibli!\" (even if you might want to). These earrings can be worn to formal events without standing out as fan jewelry and still being pretty.\nI have another Studio Ghibli tutorial already published here. I am working on more Instructables about <PERSON>'s jewelry.\nGo clay today!", "902" ], [ "Evenstar Arwen Necklace - LoTR\nIntroduction: Evenstar Arwen Necklace - LoTR\nThis is probably the most sought after piece of Lord of the Rings jewelry (besides the One Ring, of course). When I watched the movies, they came with a little brochure all about how you could go online and order replica pieces, and that was the piece I wanted. I remember specifically that I wanted a set that came with earrings and a necklace, even though I didn't even have my ears pierced at the time. I just knew that I would look like an elven princess while wearing them.\nThis is something that I have debated making for a long time but have never done. It always felt very intimidating. I saw someone else's tutorial on one a while back. Theirs was pretty, but they had changed the design. While I looked at the tutorial I thought, \"That isn't what it looks like, is it?\" So I looked up photos from the movie, and no, it wasn't.\nAs I was looking at the photos I thought, \"You know, why am I waiting to try this?\"\nSo I'm gonna try.\nSupplies\n1. Clay\n( you can use air dry or polymer clay, it is your choice. My clay is in grey because I am going to paint it after sculpting, but you can use a metallic clay if you like.)\n2. Sculpting tools ( roller, stylus tool, knife tool - if you do not have specific clay tools you can use anything that will roll and flatten clay for your roller, a toothpick or such for the stylus tool, and a regular plastic knife or an old credit card for the knife tool.)\n3. Workspace\n4. Rhinestones.\nYou need three pear shaped rhinestones and four navette shaped rhinestones. Mine are glass, but you can use acrylic if you like. The size of mine are Pear: 7 X 12mm Navette: 5 X 13mm\n5. A strong glue. I am using a Gorilla super glue.\n6.", "95" ], [ "Any of the following to give it a silver look : Metallic clay (see above), metallic paint, metallic powder (nail powder, Pearl Ex, etc.), silver leafing, or anything else you can think of that would give the clay a silver appearance. I am using a metallic paint pen.\n7. Silver Aluminum wire in 16 gauge (this is kinda a personal preference thing - this is what I had and what I thought looked best with the size of my other components).\n8. Wire cutters\n9. Varnish and brush to apply (optional)\nStep 1: Assembling the Center Rhinestones\nI have no idea what was used in the movie prop. If it is anything like any other movie props, they probably had several; some good materials and others bad materials that just had to sit there and shine during scenes that it wasn't central.\nWhich is practically all of them.\nAny way, I went with glass rhinestones. This was the hardest part of the whole project. I searched for rhinestones that I could rob off of other jewelry or clothing, but it just wasn't happening. I finally had to give in and search online.\nThen I ran into another problem. The navette rhinestone shape that is on the pendant in the movie is hard to find. I'm not saying you can't find navette rhinestones, but you mainly find the fat little ones. To find a tall, skinny shaped navette is extremely hard.\nFinally I ordered the rhinestones off of ebay. I got both my navette and my pear rhinestones from this guy's shop: Richards Rhinestones. This was my biggest expense on the project because I wanted the shine of glass, and the rhinestones I received are glass.\nAnyway, on to the project.\nLooking at photos from the movie and photos of very expensive pieces you can order offline, I understood the basic shape. Roll out your clay to a semi-thin sheet. You want to be able to press the rhinestones into the clay.\nStarting with the top navette stone, press it down into the clay. Do the right or left \"shoulder\" navette, making sure it is at an angle.\n*If you are using air dry clay, put a little bit of super glue on the back of the rhinestones before pressing them into the clay.\nPlace the bottom two pear shaped rhinestones at a downward angle that mirrors the angle of the top two navettes. I like to hold my center pear rhinestone over the piece just to check that it looks how it should.\nThe final rhinestone to go in place is the bottom rhinestone pointing straight down.", "972" ] ]

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[ [ "It's not my fault you couldn't read the receipt....\nThis just happened about 3 hours ago\nAt least 3 hours into my shift I start serving a customer (let's call her <PERSON>). In my store we can type a number, press multiply and scan one item through so it comes through as whatever number is typed (i.e if a customer wants 4 cans of beans, I would type '4x' then scan one of the cans through) and this is shown above the item I have scanned (e.g each can is 89p it would read '4 @ 89p'). This is important to the story.\n<PERSON> has a decent amount of items so a couple times I used the multiply method. <PERSON> pays and walks away from the register so I start serving the next customer.\nAs they leave, <PERSON> cuts in and looks mad.\n<PERSON>: you've charged me for 3 of these vinegars when I only bought 2.\nMe: can I take a look at your receipt?\n(<PERSON> shows me the receipt and points to '2 @ 99p' for the oven cleaner which is below this. I point this out to her)\n<PERSON>: you're wrong.", "468" ], [ "You've charged me for 3 and overcharged me. They were 49p not 99p!\nMe: ma'am the 2 thing isn't for the vinegar it's for the oven cleaner. See?\nAt this point <PERSON> keeps telling me I'm in the wrong. I also have a queue of customers lining up, a couple of them looking very baffled at <PERSON>.\n<PERSON> then proceeds to blame me for her mistake. I gave her the right answer and she didn't like it.\nMe: would you like me to call a manager?\n<PERSON>: yes please\nI then call a manager but at that point <PERSON>'s gone.\nShe had also told me apparently \"this\" was the reason her son left the store. I've never seen this woman in my life and I honestly doubt her son left here...\nTL/DR: <PERSON> needs to listen and check receipts", "329" ], [ "\"I don't care if you have a policy on painkillers - sell them to me.\"\nThis happened yesterday so the event is still fresh in my mind.\nThe store I work at has a policy where a customer can only purchase 2 packs of painkillers (ibuprofen, paracetamol and aspirin). They can't get someone else to buy for them if they already have 2 in their shopping or put 2 on another transaction.\nAs I was at the till serving one particular customer (let's call her <PERSON>), I noticed she had 2 packs of paracetamol and 2 ibuprofen. I had already scanned a few items before I got to them.\nMe: I'm sorry but I'm only allowed to sell you two of these I'm afraid.\n<PERSON>: I'll just put other two on a separate transaction.\nMe: I can't let you do that I'm afraid.\n<PERSON>: well then let my daughter buy the other two.\nMe: I'm not allowed to do that either I'm afraid. It's against store policy.\n<PERSON>: * eyes widened in rage * I would like to speak to your manager.\nMe: * who has had enough of <PERSON>'s bs * I'll call management but they will tell you what I told you.\n(My manager wasn't on shift that day but my duty manager was so I called them instead)\n<PERSON>: is everything ok?\nMe: * indicated that <PERSON> was irate.", "329" ], [ "I see a queue forming at my till so I call another 2 tills to open to bring the queues down *\n<PERSON>: she's * looks at me * telling me my daughter can't buy these indicates to the painkillers\nMe: * to my d.mc* they were in her shopping\nD.M: * to <PERSON> * because you have been told you can't purchase them, there's nothing I can do\n<PERSON>: * eyes widened even more. She turns her bag upsidedown and the stuff I've already scanned through falls out * I don't want these anymore\n<PERSON> and her daughter then storm off. Wasting her own time in the process. The gentleman behind her had a little chuckle with me after she left.\nI had to have my D.M cancel the transaction and the shopping she didn't want had to be put back.\nTL/DR: <PERSON> didn't have her Weetabix this morning and thinks the rules don't apply.\nEdit: I'm from the UK where this is a law stores have to follow. It's to prevent people accidentally or intentionally taking too many.", "329" ], [ "Things that infuriate me (tick me off) as a cashier\nNote: I might have made one of these in the past but I thought I'd make a new one in case I forgot anything\n1.Customers need to stop putting their full baskets on the conveyer belt. It's lazy and rude. Even putting every item into a washing up bowl or a bucket even a bin..... Take them all out it won't hurt you. Not doing so requires me to empty them out and you having to repack anyway\n1. Being on your phone the entire interaction. If you acknowledge me at the very least, then ok. If you blatantly ignore me the entire time, I'm just gonna stay quiet the whole interaction. And then shout \"you're welcome\" as you walk away.\n2. Putting your change down before I've scanned your shopping. Especially on top of the item. Again it's rude. Wait.\n3. Being in deep conversation with another customer or someone you came into the store with and never acknowledge me. Then when I shout \"you're welcome\" you still talk to the person you were originally talking to. Still rude.\n4. Ignoring signs on shelves that say you can only have a limited amount of items and then argue with me about it\n5. Giving me £20 when your total is under £5. (Or £50 when it's under £20) especially when it's the start of trading hours or end of the day and I don't have a lot of change left in the register. If you don't have anything smaller, pay by card. Not that difficult.\n6.", "866" ], [ "Trying to give extra cash when I've already processed the payment through.\n7. Complain when management are \"taking too long\" to get an authorisation code for your return. You were told it would take a while but you still complain. There is no estimate time. Can't wait before when I've told you, come back when you have time.\n8. Dump items from the fridges and freezers on the shelves (not cashier related but did have one customer dump a tub of ice cream on an empty bulk unit and left it. Yet where you exit, the main register is near the freezers anyway) if the item is left out too long it's considered not suitable for sale and consumption and has to be written off and thrown basically losing us stock\n9. Getting grumpy when asked for ID. Or when a minor is buying false nails and I have to refuse sale. Few times I've had to tell the adults with them that they can't buy it for them as it would be a proxy sale which is not allowed and I believe is against the law.\n10. Calling me \"babe\" especially by older men.... Unless you're my other half, don't call me that. It's creepy. Never call a stranger \"babe\" it can be classed as sexual harassment\n11. Leaving your shopping on the belt and wandering off without informing me so I'm having to have customers come to me with items to scan until they come back\n12. Hang around without queuing because you want a refund. Still have to join the queue like everyone else\n13. Not watching your children and have them cause chaos on the shop floor\n14. Leaving your kid in the car (that happened on shift yesterday - luckily it wasn't hot. she told another customer she left her 2 year old in the car. Didn't seem in a rush to get to them though)", "547" ], [ "All of this happened today.\n40 min into my shift a customer wanted to argue with me about our return policy. It's store credit for anything that was alive that is now passed away (its a pet store - fish). Not a cash refund.\nI explain this and I'm met with\n'No, I want a cash refund' -We don't do cash refunds. Store credit only.\n'they gave me cash the last time' -No they didn't. Not for a kosher return. Stop lying to me to get your way.\n'Call a manager' -Okay, but he's going to tell me to repeat myself to you.\n'When did that policy change?' -Lady, It's never changed. In fact, it's literally plastered on the wall behind me in a faded sign from 1980.\n'Well that's not your policy...' -Ma'am, Yes it is, and any employee who handed you cash in the past for a return wasn't doing their job appropriately.\n'Yes, they were doing their job because they gave me my money back' - If breaking store policy is doing a good job than we'd all be in trouble.", "245" ], [ "The lack of logic.\nThen I have another one. She has a bunny and wants to talk to me, the cashier, about bunny health. Leaning on the register, asking all the questions in the world. The line behind her starts to get longer and she's oblivious.\nI see one customer slap down some plants, get out of line and walk towards the door. I see another group of customers behind her do the same. The customer who was holding them all up starts to cause a scene about the other people causing a scene.\nThe couple who walked out yells back inside the store to the oblivious one 'You know they have employees in the back who you're supposed to get help from! You're not supposed to walk up here to ask all your questions!' and she was fucking 100% on the spot correct.\n'Oh wow, I didn't realize some people are so rude'.\nSeriously lady...YOU'RE the idiot here. I'm not a quizlet or a vet - I'm supposed to be ringing those people out.\nI'm really interested in medical coding. Bought some textbooks I'm going to study...Can't wait to walk out of this store and never come back.", "931" ], [ "Every Sunday....\nWhy is it every Sunday and Bank Holiday, people assume we're open until the end of the day?\nNormally the store I'm at opens from 8am-9pm. Bank holiday is 9am-6pm and Sunday is 10am-4pm.....\nEvery single Sunday I've worked, I've seen customers walk towards the shop well after it's closed... Surely they know the hours by now.... Even on a bank holiday.\nStill remember one NYE a couple of years back waiting for a lift home an hour after we closed and a car pulls up and I had to disappoint the poor driver and tell them the store is closed until January 2nd\nAlways 👏🏻 check 👏🏻 the 👏🏻 stores 👏🏻 trading hours 👏🏻 It's honestly not that difficult.....", "866" ], [ "<PERSON> gets shitty because I sent her to wrong aisle (I didn't, she's just braindead)\nSo this morning, we'd been open probably 5 minutes, one of the very first customers comes and asks me where an item is, to which I reply \"second aisle on the left, it looks like xyz in yellow packaging\" which is correct. I then watch her walk off and take the third aisle. A couple minutes pass and she comes back, item in hand.\nSo I said \"you found it okay then?\" smiling, interacting how i would with any other customer but I could already see her making a weird face and before I could finish my sentence she blurts out \"you sent me down the wrong aisle, it's actually the first aisle on the left bla bla bla\". Well actually no...", "931" ], [ "I reply \"technically second on the left yeah but we've got it now, anything else you need?\" I said this to finish the transaction as she hadn't actually handed it to me or put it on the counter yet to scan.\n\"No, that would be the first aisle\"\n\"Sorry but I'm not going to argue with you about which aisle it is or isn't\"\n\"Are you going to apologise to me for sending me down the wrong one\". Like I'm so sorry for misconveniencing you so much because YOU can't count aisles.. Why the fuck are you making this such a big thing. I gave her enough description about what the item looks like in the first place so she'd find it quicker IF SHE ACTUALLY WENT DOWN THE AISLE I SAID.\nI just replied the same thing \"I'm not going to argue which aisle it's down\".\n\"Oh, rude aswell as unhelpful in here\"\nShe put the item on the counter so I scanned and took card payment whilst she is pulling out all the classics.\n\"The customer is always right, you do know that don't you\" \"Have you even heard of good customer service, clearly not, that's why you're working here\"", "931" ], [ "only one left\nso one night I was closing and the last cashier (besides me) left at 8 bc his shift ended and we close at 10. fast forward a couple of minutes and my line is packed and I'm one of the fastest scanners in the front. I'm trying to get these customers out of here as fast as I can but there's also no baggers left to help (as the last bagger is doing his chores so he's busy).", "866" ], [ "this one lady as I start scanning her stuff asked me in a rude tone if there were any other cashiers open and I told her that I was sorry and that the last cashier has already left. and she asked me this like 3 times as if another cashier would pop up in the next minute. meanwhile this conversation is taking up a lot more time when I should be checking out the next customer.\nlike I'm sorry that you had to wait and I'm sorry that I'm trying to scan and bag everything by myself??? then she had the audacity to give me a stink eye pfft I just smiled and told her to have a nice night. and it didn't really help that the bagger was at the ice cooler putting more ice out bc I could see she was looking at him too lol.", "931" ], [ "Sometimes coworkers can be as bad as customers\nYesterday I was called in because someone couldn't do their shift. It was alright but my stomach starting hurting about an hour into my shift.\nSometime passes and I need to go to the restroom. I was backup cashier and finished up with the customer(ofc that customer wanted to break down the order into 3 parts and forgot something so had to run to get it). I told the other cashier(not the main cashier, the backup one) that I was going to the restroom. The line was kind of long but I couldn't hold it for much longer.\nBefore going I dropped my apron/walkie talkie into the breakroom and I saw the main cashier there finishing up her break. I go to the bathroom and come back to the register and the main cashier says \"Oh we were paging you over and over for backup\" and I replied \"I don't take my walkie talkie or the apron into the bathroom, that's gross\".", "814" ], [ "She didn't say anything.\nAfter the line dies down, I go back to doing recovery/go backs. I get called again for backup a while later and my stomach was still hurting so I go on register. With one customer I forgot to take off the sensor and it goes off when they try to leave. The main cashier goes \"Oh <PERSON>, did you forget to take off the sensor?\" and I reply \"Well if the alarms went off, I guess I did.\" and again she says nothing to that.\nI really wasn't in the mood yesterday for that. Wasn't in the mood to come in. Wasn't in the mood to be trying to do my work and keep getting called to the register. And I really wasn't in the mood for some 18 year old cashier who is high on their own farts to try and put me down or call me out for stuff.", "931" ] ]

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[ [ "<PERSON>\nThere's a wonderful visual gag early on that I thought was there just to skewer the vapid world of social media influencers, but in context with the rest of the film it also serves as a reminder to the viewer to keep on your toes.\nI tuned in hoping for another HOST or an UNFRIENDED-like experience, but this only dabbles with that sort of thing and is equally SCREAM and going on from there.\nAnd it's odd that this is yet another horror film I've seen in the very recent past that is playing with the \"killing dogs in genre films\" taboo. Seems to be a recent wave of that and I am glad to see it.", "645" ], [ "V/H/S/94\nFair play to any filmmaker who signs up to one of these things knowing they're there to support the <PERSON> segment. Turns out though that all the sections are actually worth the watch. Even the wraparound is\nrather effective this time.\nPleased I watched this with the headphones as that opening wraparound is quite spooky. A SWAT team lost in a disgusting warehouse while various static-y televisions blast out their \"movies\". A good start, especially as this is where the previous films generally suffer.\nFirst and fourth sections are quite good and made by filmmakers I'd not heard of.", "900" ], [ "It's why this is a good franchise. It doesn't need to have too many names.\nBut it's the middle-section of this thing which BANGS.\n<PERSON> EMPTY WAKE is not just a great idea (one funeral home worker having to hold a wake on their own, no guests, storm brewing, spooky stuff) but it does the idea justice. Was really disappointed with SEANCE but this did the trick for me.\nAnd of course we have <PERSON>'s THE SUBJECT. I purposefully stayed away from any synopsis and I don't think it really matters as I don't think mere words could sum up the customary insanity. He is truly a gem.\nMore of this, less shitty Halloween sequels please.", "19" ], [ "<PERSON>\nMaybe it's partly cos of where we find ourselves today, but this apocalyptic tale had me in the palm of its hand. Even when the inevitable CG kicks into gear, it wasn't off-putting at all like it so often is in grand scale movie disasters.", "909" ], [ "Which is somewhat surprising to me given that it's a <PERSON> movie and one that's helmed by the director of Angel Has Fallen Over (which I've NOT seen tbf but I have assumptions which are likely making an ass of you and me).\nVery clever to utilize the leading man's accent into a plot point so skillfully as well. People won't able to complain about that now.. *looks at Twitter*\n..Fuck sake.", "585" ], [ "Beneath the Planet of the Apes\nPretty good actually! Satisfyingly continues the dystopian nihilism of the OG while expanding our knowledge of this possible future timeline. It's telling that neither of these first two protagonists even entertain the possibility that this desolate wasteland could be Earth; it's that kind of self-assured hubris that got us there in the first place.", "462" ], [ "There's not much else on its mind beyond that, but I'll gladly accept the striking underground imagery and set design in exchange. I dig it.\nP.S. Still don't quite get the motivation behind casting another actor who looks JUST like <PERSON>...I was honestly convinced they were the same actor for almost ten minutes and was very confused 🤔", "577" ], [ "<PERSON>\nAs usual, <PERSON> style is something fun and to be admired, from the framing to color palette to awkward deadpan matter-of-fact tone of dialogue, but I've been chasing the high I felt from Moonrise Kingdom and The Grand Budapest Hotel where I believe <PERSON> really peaked in creativity, style, and storytelling.\nBoth Asteroid City and The French Dispatch have failed to impress me on that level, although I still can find enjoyment in them. They simply don't have that special something that can be found in some, well, most, earlier <PERSON> films.", "252" ], [ "Die Hard 2\nFirst rewatch in 15-20 years and I'm surprised by how much I dig this. <PERSON> reputation precedes him and casts a pall over the film, but honestly this is a pretty solid, often great, action film. It goes without saying that it lacks the magic that <PERSON> brought to the first and third installments. But DIE HARD 2 is maybe the greatest example of a sequel cash-in that merely restages everything about the first. Coming off of my first rewatch of HOME ALONE 2 in nearly 30 years, I was shocked by how lifeless and lazy it retraces the formula of the first, much like THE HANGOVER PART II. But DIE HARD 2 really makes the most of copy-pasting it's predecessor into a new, more sprawling locale. It also helps that this one minimizes the returning supporting cast and features a killer new line-up of characters (<PERSON>! <PERSON>! <PERSON>! <PERSON>!).", "995" ], [ "And while the villain of the Colonel is nowhere near as dynamic as either <PERSON>, <PERSON> breathes life into such an underwritten role.\nIt's politics are more fascinating than the film itself and stands as a crucial example of how most films have incoherent ideologies. By the measure of today's woke liberal cultural analysis, this technically qualifies as copaganda, and like most every action film it's values are right-wing conservative. But DIE HARD 2 constantly oscillates between a pro and anti stance on everything it depicts. <PERSON> is an individualist supercop, while the other officers are bureaucratic buffoons. The military is both the villain and savior (only later revealed to be a ruse). But it's pro-authoritarian individualism is also steeped in an anti anti-communism, with it's entire plot revolving around the murderous insanity of American military cold war beliefs (the plot is literally a US army officer murdering countless civilians to protect a CIA-backed right wing fascist who killed communists). But that's not to say that this is pro-communism. Even it's depiction of the media is confusing and mercurial: journalism creates panic, gets in the way of authority, but also can be a force for good? If anything, this might be the perfect text on the confusion and contradictions of American individualism, one that worships systems of authority while conveniently making them the enemy when they challenge the supercop individual.", "952" ], [ "Burn After Reading\nOne of the most relentlessly evil comedies I can think of. Honest though. Brutally honest.\nI made too much hash out of delineating the Brothers in my DRIVE AWAY DOLLS blurb, but there there really is something breathless about the PERFECT editing and Cinematography calibration of these comedies.\nThe right lenses give the right weight, the right edits play the right moments.", "862" ], [ "An almost obsessive interest in character behavior punctuated and reveals.\nI have some understanding that DRIVE AWAY DOLLS is attempting to embrace a visual language that is separate from that formal control...I just prefer the violent effectiveness of the formal control. That's just me though. I wish it was present in that movie.", "645" ], [ "Talk to Me\nFeels like the good concept-heavy horror films of the 2010s like It Follows but bogged down by the more modern Hereditary / Us family drama that I really don't find much interest in. If this didn't screech to a halt halfway through to focus on a non-interesting mother-daughter plotline then it'd be really really good for me I think.\nI still don't care much for the ooey gooey designs of the spirits, but the vibes are fun until that point and the concept is real neat throughout. Some great haunting moments here and there, but I'm getting very tired of the <PERSON>-bash-his-head-into-school-desk shtick.\nHaving spoken negatively about the main plotline however, I do think a film has never won me over by such a far margin as this one by its ending.", "823" ], [ "Brings it all back in a really rewarding way that condemns the character appropriately. Made me smile all silly like. Sequel already in the works tho 🪨", "583" ] ]

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[ [ "How to Make Wired Crystal Earrings\nIntroduction: How to Make Wired Crystal Earrings\nWhile I don't have a Youtube video for this one, I actually fell in love with these beads and have been wanting to make something with them for a while. I came up with these fun wire wrapped earrings. I had these Screw-back earrings that needed something special so I whipped up this little number. Literally took less than five minutes so lets get to crafting!\nI will have a future Youtube video on this, but currently, it is anon.\nSupplies\n* Crystal Beads\n* Earring jewelry pieces\n* matching jump rings\n* matching wire *the string is there in the picture for comparison*\nhardware\n* wire cutters or scissors\n* jewelry pliers\nEXTRA:\n* jewelry glue/ E6000\n* ruler\nStep 1: Picking Your Crystals\nIt's super important to know what size you want for your crystals. You don't want them to be too heavy for your ears. Otherwise how else are you going to wear them?\nStart this project by picking out the crystals that you like. They don't have to match but do make sure that you have two.\n*NOTE* If you feel adventurous in this step after making your first pair, feel free to do multiple crystals.\nStep 2: Step 2: Wire Length\nWith your crystals now chosen, it's time to add the piece that's going to hold them together: THE WIRE~!\nGrab your wire and measure a small length that can wrap around the crystal more than once.\nCut that two pieces of that length.\n*NOTE* It is totally okay to have too much wire. You can totally use a ruler here to make sure you have the exact measurement of wire.\nStep 3: Step 3: Wrapping It Like a Present\nTime to WRAP IT UP!\nSince mine are beads, it's a tad easier. If they're not just hold on.\nFor those that are using beads like I am. Follow this:\n1. String the wire through the crystal bead.\n2. Make the bead the center of the wire.\n3. Twist one end of the wire around the crystal bead.\n4. Twist the other end of the wire the opposite direction.\n5. Twist the two wires together at the top of the crystal.\nFor those who are using just crystals follow this:\n1. Find the middle point of your wire.\n2. Firmly press the wire into the crystal holding them together.\n3.", "972" ], [ "Use one side of the wire to wrap around the crystal to the top.\n4. Use the other side of the wire to wrap the opposite direction of the crystal to the top.\n5. Twist both wires together at the top of the crystal.\nIf you feel like the wire is a bit loose, add a tiny DROP of jewelry glue or E6000 to the bottom of the wire or any other connection points.\nStep 4: Step 4: Preparing Your Earrings\nI have screw-back earrings so they're different from normal fish hook earring hangers. Do not let this deter you from completion.\nAdd a jump ring to your earring.\nStep 5: OPTIONAL: SPIRAL CURLLY TAIL\nWith one of the wire tails, I decided to turn it into a spiral for extra flare. It's optional.\nThis is definitely a medium difficulty and takes a bit to get right.. but if you're up for the task. Lets go~\n1. Take one of the wires of the tail and curl it with needle-nose pliers.\n2. Twist it until it becomes a closed loop.\n3. Using the pliers hold the loop at the very tip and slowly press the wire around the loop: NOT the pliers.\n4. Release the little loop, rotate the loop slightly holding the curve in place, and grab it again with the pliers.\n5. Slightly press the wire again around the loop not crossing any of the current wire thats inside the pliers.\n6. Repeat steps 4-5 until you have used up all the wire.\nIf you've done it correctly you've created a spiral!!!\nStep 6: Add Your Crystal to the Earring Piece\nWe're almost done last step!!!\n1. With one of your tails bend it in the middle to make a hook.\nIf you want your earrings to be longer bend the wire more at the end.\n2. String the jump ring connected to the earring to the bent wire.\n3. Bend the wire back into the crystal.\n4. Stuck the wire into some of the existing wrapped wire or twist around the top of the crystal if you have enough length.\n5. Cut off the excess.\nStep 7: <PERSON> Would Be Proud~! You've Finished the Project!", "902" ], [ "Beginner Jewelry: Wooden Photo Earrings\nIntroduction: Beginner Jewelry: Wooden Photo Earrings\nThese are actually some of the first pieces I ever made when I started getting interested in making jewelry. I wanted some fan girl jewelry and couldn't afford to just go buy something, so I needed to make it myself. At the time I was in luck because I had a wooden necklace that had broken and was irreparable, but I had kept the wood pieces, and these became my base.\nSince I was able to do it as a beginner, I think that these wooden photo earrings are definitely a project that the jewelry artist who is just starting out will benefit from. Even those of us who have been making jewelry for a while could get some joy out of earrings with photos of our choice on them.\nI am using my own photos for this Instructable. You can use whatever you like, just please keep in mind that if you sell earrings like this your photos will need to be your own.\nSupplies\n1. Wood pieces: you can use scrap pieces you have or buy some premade. I'll talk more about this is the second step.\n2. Electric drill\n3. Small drill bit: mine is a #55 with a 118 degree point\n4. Sandpaper, fine grit (you may decide you don't need this)\n5. Photos or drawings (not pictured)\n6. A computer or laptop with a word document program (not pictured)\n7. A printer with colored ink (if your photo is colored). Mine is an inkjet. (not pictured)\n8. Regular white copy paper\n9. Scissors\n10. Pen or pencil\n11. Mod Podge or Polyurethane Varnish or some other sealer\n12. Brush\n13.", "95" ], [ "A pin (you don't have to have it)\n14. Round-nose pliers\n15. Jump Rings\n16. Earring Hooks\nStep 1: Wooden Pieces\nThe wooden pieces should have a flat or pretty much flat side to them. They can be whatever size you want, but you want them to be a size that you can wear comfortably.\nAs I said earlier, you can use scrap pieces of wood if you have any. You will probably have more work because you will need to sand your scrap pieces to make them smooth and to shape them.\nIf you don't have scrap pieces, or you don't want to mess with that, you can buy premade little wood circles, squares, and other shapes at craft stores. I bought mine at our local chain craft store. You can even find them at Walmart. You just want pieces that are pretty thin and the diameter you want.\nSince I bought a variety pack, I have a couple sizes to pick from. I am going to use the largest circle size I have (you can see in the photo how big it is), but size is up to you.\nStep 2: How to Remove and Add a Drill Bit\nI put my #55 micro drill bit into the drill.\nOn my drill you hold the chuck (the piece were you put the drill bit) while you run the drill in reverse. This causes the end to open up so you can remove the drill bit that is in the drill.\n(The reverse/forward button is a little push in button that you should find somewhere above the speed trigger. You push on it one way and the drill runs in reverse. Push it in the other way and the drill will run forwards.)\nThen I place my #55 drill bit in the end and hold onto it with a few of my fingers so I can make sure it is straight. I turn the drill to run forwards. Slowly I run the drill until the end closes around the drill bit.\nNow we are ready!\nStep 3: Drill\nPlace your wood piece on a surface that you can safely drill on (not the kitchen table). Remember that your drill bit will be going all the way through the wood.\nYou may want to mark with a pen or pencil where you want the hole. You can carefully hold onto the wood piece with one hand while running the drill with the other. Just make sure your fingers are no where near the drill bit.\nHolding the drill straight up from the wood piece, place the bit where you want the hole. Slowly run the drill forwards until it goes all the way through the wood.\n*Alternatively, hold the piece in your fingers while you drill, but this is more dangerous! Be careful!\nTurn the drill to reverse, and run the drill as you bring the drill bit out of the hole. This helps make the hole smooth.\nMake sure to do this slowly because if you go too fast you may cause your piece to move or you might crack the wood.\nStep 4: Sand (optional)\nThe hole might have little rough edges, so we will sandpaper that.", "56" ], [ "How to Make Fairy Tights\nIntroduction: How to Make Fairy Tights\nFirst and foremost:Thank you for selecting this tutorial to become magical. You're on your way to being one step fancier than the rest.\nTo help the tutorial I highly suggest watching my Youtube video on how to create them.\nThese are based on the tights <PERSON> created. However to my dismay, I can no longer purchase them, so I decided to make some for myself.\nThis is a fun project that easily turns into a lot longer of a project if you get too wrapped up in it. So let's get started!\nYou can totally use some old torn-up tights or fishnets that need some love. I had these old fishnet tights that I bought on sale and never used that are featured in my Youtube video.\nSupplies\n* Fishnet tights\n* sewing needle and thread\n* fabric flowers\n* cabochons aka flatback pearls or flatback rhinestones\n* thick paper or thin cardboard\n* scissors\n* beads\n* universal adhesive or E6000\nStep 1: Step 1: Picking Your Tights\nIn my supply list I say Fishnet tights. I haven't tried other tights but make sure you have a pair that works for you. It's extremely important to mention that the tights I used have a wide netting. The wider the netting the looser the cluster is going to be. The smaller the netting the better to have more clusters.\nWhile I have only done this with fishnets, I can imagine you can perform this on normal tights. I do not really recommend this tutorial on thigh highs because they might get heavy depending on how big your design is.\nStep 2: Step 2: Pick Your Materials\nPicking your materials to make yourself into a fairy is HUGE... well maybe not a fairy but if you want to feel like the magical creature you are and wanting to bring it to life, you need the special ingredients to make it happen. We can't say magical words to make it happen like the storybooks unless you can just wave a bank card and ta-da you have magic tights that way.\nBUT WE PREFER THE DIY ROUTE HERE. So the ingredients other than tights would be~~~\n-Cabochons aka flatbacked half-beads/icons are one of the best things I recommend here.\n-Fabric flowers are great for this.\nI don't recommend paper flowers because the tights will not be washable. If you live in a rainly location, this might also ruin them too.\n-Sequins of all shapes and sizes. Sequins are a great way for you to create your own flowers or shapes if you don't have access to other unique bits.\n-Assortment of beads.", "294" ], [ "Definitely great for filler or attaching your sequins on. The more shapes and sizes the better you have a chance to play around with your design.\n-Needles and thread. This is definitely the best way to attach all of your beads and findings to your tights.\n-Glue. And I mean the toughest hardcore glues out there. I prefer using E6000 or clear contact glue for this as it's strong and holds it all together. This is perfect for the cabochons and anything that might be heavy.\n-Small embroidery pieces or lace. You get the point I hope? You can go big if you want.\nJUST LETTING YOU KNOW!\nThis is the perfect time to create a layout or color scheme for your tights. It seemed to work better when you have a color palette to choose from.\nSuch ideas:\n* pink, teal, blues\n* white, iridescent\n* Holiday-themed\n* cabochon based\n* favorite colors\nStep 3: Step 3: Wear Your Tights~!\nExtremely important.WEAR YOUR TIGHTS. You need to wear your tights to see where you are going to place your pretty things.\nGive yourself a guideline of how high and low you want the design to go. Make sure you understand how much you want to wrap around the leg as well. Highly do NOT recommend wrapping around to the back of the knee cap. It'll feel really weird there so I recommend keeping the backside clean for sitting and walking purposes.\nI'm using a small piece of cardboard/cardstock underneath my tights as my working area. This is super important so you don't get glue on yourself or poke yourself with a needle. It's almost like an embroidery hoop but for your tights.\nStep 4: Step 4: Add Your Pretty Things!\nBefore you start working, make sure to get a good stretch in as you'll be wearing these and working on them at the same time. I've tried a different process and it just doesn't work well unless it fits your body.", "316" ], [ "Easy Jewelry Repair for Common Jewelry Breaks\nIntroduction: Easy Jewelry Repair for Common Jewelry Breaks\nJewelry often breaks. It's just a fact of life. No matter how fancy or cheap, tough or delicate, wearing jewelry causes it to break.\nToday I'm going to walk you through how to repair common jewelry breakage issues. If you wear jewelry, you will run into at least one of these problems.\nSupplies\nI will list the supplies under each specific break issue because that will be much less confusing. Here is a list of contents so you can skip ahead to your specific need.\n1. Broken Jewelry Chain\n2. Lost Earring Back\n3. Broken Stud Earring\n4. Broken Necklace Clasp\nStep 1: Broken Jewelry Chain\nSupplies:\n- Round nosed pliers OR Rosary pliers (using two pliers makes this a lot easier)\n- Broken chain\n- Optional: jump rings\nOne of the most common problems is a broken chain. Those tiny little links break SO easily.\nLuckily, they are a rather easy fix. Here I have two ways.\nTake the broken link out of the chain and discard it. I find that most of the time the broken link is practically impossible to repair, so just get rid of it.\nHold on to the first link on the chain end (the one that was next to the broken link) with one of the sets of pliers. Look and make sure that where the link opening is is facing up. Take the second set of pliers and grip the other side of the loop. The loop opening should be in between the two sets of pliers. Twist one of the pliers, causing the loop to open sideways (don't pull it open).\nUse your fingers or the second set of pliers to hook the other side of the broken chain in the now open loop. Use both pliers again like you did earlier, but this time twist the loop shut. Your chain is repaired.\nSometimes I like to kinda smash the new link shut just to make sure. Not really pretty, but functional.\nA second option is to get rid of the broken link, open a jump ring, and pass it into the two end links of the broken chain.", "902" ], [ "Try to find a jump ring that is a similar size to your chain loops and it will be practically invisible. This is easier than opening the actual links of the chain, so if you have a hard time working on such a small piece, I advice using this route.\nStep 2: Lost Earring Back\nSupplies:\n- Silicone Earring Stoppers\nOR\n-Hot glue gun stick\n-Knife\nEarring backs are so easy to lose. They just pop off and disappear. There is the old \"eraser\" repair, but I find that it doesn't really work for me, and having a piece of pink eraser stuck to the back of your ear is kinda obvious. Here are two ways you can fix a lost earring back.\nThe first way is kinda obvious. Silicone Earring Stoppers. They come with a lot of hook/hoop earrings that you buy, and they are actually what is inside clutch backs. If you look at one, you can barely see the silicone piece inside. When you buy earrings, keep those silicone pieces! I find they come in handy all the time. If you don't have any, you can easily find some online or in the store.\nNow here is a better hack for if you don't have any. A hot glue stick.\nCut a little bit of the end of the hot glue stick using a knife. Take the earring and push it into the hot glue round. This is your new back. It can be a little difficult to find the hole you made in the hot glue when putting it in, but once you have this back isn't really gonna move. Plus, it is clear so it won't be that noticeable. and even if it is people will just assume it is a normal earring back instead of a replacement.\nI was actually super pleased with how the hot glue back turned out. I liked it a lot and I need to try to remember it more when someone says they lost an earring back. A plus is that since the hot glue round is larger and flatter than most post backs, it will also help hold the earring up like those \"ear savers\"!\nStep 3: Broken Earring Stud\nSupplies:\n-Post backs (available in craft stores or online)\n-Gorilla Glue\nI have found that Gorilla Glue is a pretty trustworthy glue with repairing metal items. As long as you are not tugging or pushing on it, it should hold.\nThe post backs are easily available in different places. I wish I could tell you some awesome hack for them, but there really isn't one.", "320" ], [ "Pumpkin Ring : Fall Jewelry\nIntroduction: Pumpkin Ring : Fall Jewelry\nI love pumpkins.\nI actually don't like to eat them. I just like to grow them and have them for their cuteness. So for me, one of the biggest things in fall is pumpkins in their original or jack o' lantern form. Sometimes I feel like all I make is earrings, so I decided to make a pumpkin ring instead. I wanted this ring to be more adult and not the clunky plastic pumpkin rings you see in the store at this time of year. So let's make a ring to celebrate pumpkins!\nSupplies\n1. Clay in orange (or whatever color cuz we will be painting it later)\n2. A stylus tool or a large sewing pin\n3. Copper wire in 24 gauge (just a small gauge *thickness*; it doesn't have to be 24).\n5. Wire Cutters and Round-nosed pliers\n6. Paint in light brown, dark brown, orange, and light grey.\n7. Varnish (I use Duraclear).\n8. Brush to apply paint & varnish\n9. Copper in 18 gauge\n10. Metal file\n11. Ring mandrel\nIf you don't have a mandrel, don't worry; I'll shoe you what to do.\nStep 1: Design & Sculpting the Pumpkin\nI tend to just make scribbly designs for my jewelry. Since I make them with the pen I use in my notebooks, there is often a bunch of things that have been scratched out.\nI show you all this scrap of design work to help you realize you don't have to be a superb artist to draw out your ideas. This can help you visualize that piece of jewelry that is in your head but you don't know just exactly how go makr it. Here my scribbles helped me figure out how attaching the pumpkin was going to work.\nNow let's sculpt a pumpkin!\nPumpkins are pretty easy to sculpt.", "95" ], [ "You can make TONS of them in a matter of an hour (ask me how I know), but we only need one.\nTake your clay and make a small ball type shape (doesn't have to be perfect). Size is a preference, but mine is about as big as the end of my thumb.\nWith the needle tool, begin making lined on the orange clay. Don't make them too deep, but don't make them too shallow. For a pumpkin that is less round and more ridged, use the side of the needle tool and push it into the pumpkin's sides to make ridges.\nMake the needle marks go all the way to the top of the pumpkin.\nNow go back and make finer details with the needle tool. I like my pumpkin to have lots of lines.\nTo give my pumpkin a flatter shape, I press it down a little on my work surface. I then go back with my needle tool and re-detail parts that got squished.\nI want my pumpkin to sink in a little where the stem meets it, so I take the end of my needle tool and press it into the top to make a dent. You can use any smooth blunt object for this, even a finger tip.\nTake a tiny piece of clay in a log shape and press it to the top of the pumpkin. Using the needle tool, draw skinny lines in the new stem, pressing harder near the bottom so you join the pumpkin and the stem. Once your stem is as detailed as you like, you can leave it standing straight up or do what I did. I used my needle tool to bend the stem over on itself to make a little loop.\nThe pumpkin is finished being sculpted!\n* And please ignore my beat up hands. It all comes of taking apart sharp stuff without gloves.\nStep 2: A Way to Attach the Pumpkin\nWe need a way to attach the pumpkin to the ring. Now we will use our thin copper wire. The wire will go in the base of the pumpkin and then wrap around the ring we will make in the next step.\nWith the wire cutters, cut off a piece longer than you think you need. Mine is about 5 or 6 inches. You don't want to come up with too little wire when you wrap it on your ring base.\nBend a small kink in the end of the wire. Now poke that end into the bottom of the pumpkin.\nNow, bake the pumpkin or let it dry, depending on the type of clay you used.\nStep 3: If You Don't Have a Ring Mandrel\nIf you don't have a mandrel, don't fret. Simply look around for a cylindrical object aboug the size of your finger. Take an existing ring of your and put it on the object, testing if it will fit. You want it to fit snugly, but not tight.", "286" ], [ "Howl's Moving Castle Earrings- Studio Ghibli\nIntroduction: Howl's Moving Castle Earrings- Studio Ghibli\nHowl's Moving Castle is one of my favorite Studio Ghibli movies. I find it inspiring.\nOne of the most sought-after pieces of Studio Ghibli jewelry is Howl's jewelry set. They sparkle like magic and are pretty pieces in themselves without having belonged to a handsome wizard. Today I am going to show you how to make your own Howl's Moving Castle earrings. I will be publishing Instructables on the necklace and ring as well.\nSupplies\nEarrings:\n1. Clay in green\n2. Eyepins\n3. Gold hook earrings\n4. Two small glass red seed beads\n5. Wire in 24 gauge\n6. Pliers\n7. Green pastel\n8. Knife or toothpick to scrape and mix pastel\n9. Soft brush\n10. Triple Thick (or TLS for polymer clay)\nStep 1: Sculpt Teardrop Shapes\nWith the green clay, roll it between your fingers, making one end smaller than the other, to make a teardrop shape. Insert an eye pin at the top of the tear drop. Make two. They should be about as long as a quarter is from side to side.", "95" ], [ "Bake or leave to dry.\nStep 2: Adding Red Gems\nGet out the gold earring hooks, piece of wire, and the glass red seed bead. With the round nosed pliers, curl one end of the wire piece into a loop. Slide the red bead onto the wire. The loop will stop it from coming off at the end.\nTake the round nosed pliers and curl a second loop on top. You will probably have to remove your pliers and pinch it closed. Now the bead should be trapped by the two loops.\nOpen the loop on the earring hook by twisting the loop sideways where it meets. Don't pull it open. Slide on of the loops on the piece of wire onto the loop on the hook, then twist the hook closed, trapping the bead's wire loop on the hook. Do the same for both pieces.\n*If you had gold wire it would be more accurate, but I didn't have any, so I had to go with silver.\nStep 3: Attach Earrings\nGet out the dried/baked tear drop shapes. Open the loop on the eye pin on the tear drop shape. Hook it to the end loop on the bead wire, making it hang from the bottom. Close the eye pin loop.\nStep 4: Triple Thick Varnishing\nTo give them a bit of a luminescent appearance, I will be varnishing them with Triple Thick mixed with green pastel. I chose a darker shade of green pastel so that they could look like they \"glowed\" from within.\nScrap off the pastel stick into a powder. Mix this powder with a bit of Triple Thick varnish. Continue mixing until you get an even color.\nWith a brush, apply the colored Triple Thick to the teardrop shapes. Be careful not to overwork it; you can go back and add another coat later, but if you keep brushing what you have applied it will become lumpy.\nI applied three coats in total.\nStep 5: The Earrings of <PERSON>\nAnd there you have it! You have these magical earrings. You can sport your Studio Ghibli style without screaming, \"I love Studio Ghibli!\" (even if you might want to). These earrings can be worn to formal events without standing out as fan jewelry and still being pretty.\nI have another Studio Ghibli tutorial already published here. I am working on more Instructables about <PERSON>'s jewelry.\nGo clay today!", "902" ], [ "Water Marble Earrings - Easy\nIntroduction: Water Marble Earrings - Easy\nTie-Dye screams summer time!\nThese earrings are reminiscent of tie-dye by using the water marble nail technique. This was a really hot thing a few years ago, so I decided to revive it but it in a new way: earrings. With this technique you can have earrings in whatever colors you want with very little supplies.\nIf you have ever water marbled your nails you are ready for this Instructable! If you have never done water marbling, don't worry; it is pretty easy to get something cool with little effort. With a little practice, you can come up with eye popping designs for the summer!\nSupplies\n1. Newspaper or paper towels to protect your work surface.\n2. Extra paper towels for your hands.\n3. Nail polish in various colors*\n* I will note that some nail polishes don't work as well for water marbling as they just sit on the water and don't spread. You can still use them, but you are gonna have to push them around a lot more than nail polishes that will spread. I found that LA Colors doesn't spread, but Sally Hansen, Sinful Colors, and Broadway Nails do. However, sometimes I think it honestly varies bottle to bottle, but not necessarily brand to brand. I found some colors of a brand would work while others wouldn't, so you should do a test first to see if your colors will work.\n4. Tooth picks or pencils, or other pointed instruments for swirling the polish.\n5. Nail polish remover\n6. A cup or small dish (use one you can just throw away or one that will be ok to clean with nail polish remover, such as glass).\n7. Water at room temperature.\n8. Cotton balls to use with the nail polish remover to take the nail polish off your fingers.\n9. Little wooden pieces. I bought mine at a local craft store, but you can buy them off of Amazon. These ones are squares, but you can get cool shapes, too. (example: square 1X1 inch pieces )\n10.", "994" ], [ "Varnish - not necessarily necessary, ha ha, but I like it. I am using Duraclear Gloss Polyurethane Varnish.\n11. A brush to apply varnish.\n12.Earring components - I am using flat back post earrings like these on Amazon, but you can use french hooks if you like.\n13. Super Glue. I am using Gorilla Super Glue Gel.\n14. FOR HOOK EARRINGS ONLY: A pair of round nosed pliers, two earring hook pieces, two jump rings, a battery powered drill, and a small drill bit.\nStep 1: Prep Work\nFirst, prepare your work area. This project moves quickly, so it is important to have everything on hand.\nSpread paper towels or newspaper over your work surface so you don't risk ruining your table surface, or the floor, or the desk, or whatever you are using. Not fun to realize that you got bright blue nail polish on the dark wood table halfway through your craft time.\nPlace your nail polish bottles and tooth picks close at hand. You want to be able to grab the next color quickly.\nPour some of the water into the cup. You want it to be about 2/3 of the way full so it is easy to dip the pieces in and out but also not spill water every where.\nUnscrew the tops of the nail polishes that you want to use. This way you aren't pausing to unscrew the caps and wasting time.\nWith your little wood pieces waiting, you are ready to go.\nStep 2: How to Water Marble\nPick your first color. You can do as many colors as you like, or only two. Know what you plan to do before you start so that you can do the design as quickly as possible.\nWith the first color ( I am using bright green) get the nail polish brush full of polish and hold it over the water so it will drip into the water. Don't hold it too high above the water or the nail polish will simply go right through the surface of the water and end up as a little nail polish ball on the bottom of your cup. Do one drop or multiple drops. The nail polish should hit the water, stay a dot for a moment, then begin to spread out. It is really cool to watch.\nDo your second color, dripping right into the center of the first color.\nContinue to do this for as many colors as you like. I am using four (green, pink, yellow, and blue). I also start to just place the dots randomly wherever I feel like. Just remember that you have to work fast.", "1013" ], [ "\"Magic\" Studio Ghibli Earrings\nIntroduction: \"Magic\" Studio Ghibli Earrings\nIn the Studio Ghibli movies, there is a set of earrings (or very similar earrings) that are worn by various characters, most of which are magic types. Characters who are seen wearing these are <PERSON>'s mother, <PERSON> (<PERSON>'s Delivery Service) <PERSON> (<PERSON>'s Moving Castle), <PERSON>'s mom, <PERSON> (<PERSON>), and <PERSON> ( <PERSON> of The Valley of the Wind). The earrings are a red, teardrop dangle. I don't know if there is any specific connection, but I noticed it was a common theme.\nIf you want a subtle way to sport your love of Studio Ghibli movies, these earrings may magically give you the answer!\nI will show two different ways to make these earrings.\nSupplies\nVersion 1: With Glass\n1. Two glass teardrop pendants in red\n2. Round nosed pliers\n3. Copper wire in 24 gage (or bigger, depending on preference, I want mine to be practically invisible).\n4. Gold earring hooks\nVersion 2: With Clay\n1. Clay in red (or you can paint it) *polymer clay or air dry\n2. Eye pin\n3. Various clay tools (if needed), I recommend a roller and stylus tool, but I'm not actually going to use any tools.\n3. Varnish OR TLS, depending on if using air dry or polymer clay\n4. Soft pastel in red\n5. Toothpick or other tool for scraping off and mixing pastel\n6. Soft brush\n7.", "95" ], [ "Gold earring hooks or post earrings for diy earrings\n8. Pliers\nStep 1: V1: With Glass\nFirst, grip the end of the copper wire at the very base of your round nosed pliers. Wrap the wire twice around the base, then move the wrapped wire a bit up the plier nose and wrap again. Keep moving the wire upward while wrapping until you have a small spiral when you pull the wire off.\nPull the spiral off and grip it with the pliers. The wire that comes from the center should be bent upwards so the spiral forms a little foot or base.\nStep 2: Add the Bead\nMeasure your wire by holding the glass bead next to the wire.The spiral will be at the bottom of the bead . Cut the wire with excess for making an eye loop.\nSlide the glass teardrop bead on the wire.\nGrip the wire that comes from the top of the bead, pulling until the spiral is snug against the base of the bead. With the pliers, bend the wire to a horizontal position. Wrap the wire around the plier to make a small loop.\nWrap the excess wire around the base of this loop until all the wire is used (you can tuck the tail inside the bead if you prefer).\nDo this step for both beads.\nStep 3: Add Earring Hooks\nAdd earring hooks by twisting the loop on the earrings sideways to open the loop (don't wrench it open). Slide the copper wire loop onto the gold loop and then close the gold loop.\nYou are finished!\nStep 4: V2: With Clay\nTake a ball of red clay and shape it into a teardrop shape by rolling it and pinching it with your finger. It should be about as long as an American quarter is wide.\nPoke the eyepin into the top of the tear shape.\nMake two.\nLet the clay dry or bake as your clay instructs.\nStep 5: Add Earring Hooks\nOpen the earring loop by twisting it sideways with the pliers. Don't pull the loop open; twist it.\nAdd the pendant and then close the loop by twisting it back to its original position.\nStep 6: Colored Varnish\nI get a little bit of the Triple Thick on a container lid and then scrape pastel onto the varnish. I mix the pastel dust thoroughly with the varnish so there are no flecks of pastel dust.\nThen just apply it with a soft brush. I do several coats to try to give it a bit of a \"glass\" appearance. Let it dry for a day at least between coats, otherwise it will remain tacky.\nIf you like, you can mix up a good amount of this colored varnish and store it in a small airtight jar so that you can quickly swipe another coat on without having to mix the pastel every time. That is what I am going to do so that it saves me time!\nStep 7: Finished!", "902" ] ]

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[ [ "Zimbabweans Mock Suspended Opposition Leader on Twitter · Global Voices\n<PERSON> with <PERSON> cutting the wedding cake at at the Glamis Arena. Photo used with permission from nehandaradio.com\nAs former Prime Minister <PERSON>’s Movement for Democratic Change (MDC) implodes amid infighting for the party leadership, Zimbabweans took to Twitter and found humour in what others have described as a “Greek tragedy.”\nRebels within the party led by MDC Secretary General <PERSON> suspended <PERSON> and other senior officials accusing them of resisting leadership change and failing to oust president <PERSON>. <PERSON> says that he is still the party leader.\nZimbabweans, who call themselves “<PERSON>”, had a field day suggesting titles for an imagined book about <PERSON>, and the wisecracks came fast and funny.\n<PERSON> started the Twitter conversation that inspired some creativity among Zimbabwe’s Twitter users with the challenge:\n#<PERSON> I dare u to come up with a #TitleforMorgansBook after ths mess @SirNige @263Chat @deltandou @CynicHarare @RangaMberi @ConorMWalsh\n— <PERSON> (@fingerray) April 30, 2014\nPlaying on both the movie “12 Years a Slave” and <PERSON>’s tenure at the helm of the MDC, <PERSON> tweeted:\n@phirimarko @SirNige @263Chat @deltandou @CynicHarare @RangaMberi @ConorMWalsh @nematombo @teldah @cchabikwa @ChrisNqoe 15 years a slave\n— <PERSON> (@fingerray) April 30, 2014\nHe wrote again:\n<PERSON> @SirNige @263Chat @deltandou @CynicHarare @RangaMberi @ConorMWalsh #titleformorgansbook They said I was like <PERSON>\n— <PERSON> (@jpmatenga) April 30, 2014\n<PERSON> suggested:\n@fingerray @263chat @cchabikwa @chrisnqoe @cynicharare @deltandou @phirimarko @rangamberi @sirnige @teldah “A Series of Unfortunate Events”\n— Conor Walsh (@ConorMWalsh) April 30, 2014\n<PERSON> wrote:\n<PERSON> @SirNige @263Chat @deltandou @CynicHarare @RangaMberi <PERSON> The Man Who Wouldn't be King\n— <PERSON> (@phirimarko) April 30, 2014\n@jpmatenga suggested a self help book:\n@fingerray @SirNige @263Chat @deltandou @CynicHarare @RangaMberi <PERSON> #titleformorgansbook how to lose friends in 10 days\n— <PERSON> (@jpmatenga) April 30, 2014\n@__The_Duke came up with:\n<PERSON> My Lifestory:From The Frying Pan To The Fire. #TitleforMorgansBook\n— Guzzler (@__The_Duke) April 30, 2014\n@George_Ruzv wrote:\n@deltandou @cchabikwa @fingerray @SirNige @263Chat @CynicHarare @RangaMberi @ConorMWalsh @TVYangu “The End.”\n— <PERSON> (@George_Ruzv) April 30, 2014\n@DeltaNdou joined in:\n@cchabikwa @fingerray @SirNige @263Chat @CynicHarare @RangaMberi @ConorMWalsh @TVYangu “Being the face of the struggle & butt of every joke”\n— <PERSON> (@deltandou) April 30, 2014\n@RickyEMarima wrote:\n@ConorMWalsh @263Chat @CynicHarare @deltandou @fingerray @RangaMberi @SirNige The Great Betrayal.", "424" ], [ "Zimbabwe Police Arrest Top Human Rights Lawyer · Global Voices\nOne day after millions of Zimbabweans approved a new constitution that will bring about presidential and parliamentary elections later this year, prominent Zimbabwean human rights lawyer <PERSON> was arrested after demanding a search warrant from police who were attempting to arrest her clients.\nPolice detained <PERSON> and her four clients, all officials of the Movement for Democratic Change, the party of Zimbabwe's Prime Minister <PERSON>, on March 17, 2013. She appeared in court two days later to answer charges of obstructing justice after Zimbabwe police ignored a court order to release her.\n<PERSON>, who was described by the New York Times in 2008 as “Zimbabwe's top human rights lawyer”, has been targeted in the past by police and the feared Central Intelligence Organisation (CIO), a secret police force which critics say President <PERSON> uses as a tool to suppress dissent.\nHer arrest comes on the heels of a referendum in which nearly 95 percent of voters approved a new constitution for Zimbabwe. The new charter will see <PERSON> and <PERSON> face off against each other in elections expected this summer, marking the end of the pair's coalition government formed after disputed results in the 2008 elections led to violence.\n<PERSON> in the back of a police van. Photo courtesy of Zimbabwe Lawyers for Human Rights\nZimbabweans took to social media to express their dismay at <PERSON>'s arrest.\n<PERSON> (@Dewamavhinga) wrote:\n<PERSON>: president <PERSON> & his family in Rome for Pope <PERSON>'s inaugaration – back in #Zimbabwe lawyer <PERSON> remains in police custody\n<PERSON> (@cchimakure) tweeted:\n<PERSON>: No joy yet for <PERSON>.", "424" ], [ "She is still in police custody despite High Court order. It seems rule of law is alien.\n<PERSON> (@sokwanele) posted an action alert:\n@sokwanele: ACTION ALERT: Stand by the woman who would be the first to stand by YOU if your rights were being violated: http://bit.ly/15h0cL6 #zimbabwe\nEducation Minister <PERSON> (@DavidColtart) praised <PERSON>:\n<PERSON>: Well done <PERSON> – many of years of consistent and courageous upholding of the rule of law. Amhlope! [congratulations]\n<PERSON> (@DavidColtart) later tweeted:\n@DavidColtart: It is very difficult to adequately convey the depth of my disgust at the ongoing detention of <PERSON>…. http://fb.me/1tRXqejo2\n<PERSON> ‏(@TrevorNcube) wrote:\n<PERSON>: Sad that <PERSON> has spent another night in custody for doing her legitimate work.A reminder that #Zimbabwe still far from normal\n<PERSON> ‏(@Kudzi_Siphiwe) reacted:\n@Kudzi_Siphiwe: Really disturbed about <PERSON>, even more disturbed by people who continue to defend the indefensible.\n<PERSON> ‏(@KadomaKid) noted:\n@KadomaKid: This <PERSON> thing is now just getting out of hand , the cops need to perform better than this!\n<PERSON> ‏(@MthandazoNyoni) asked:\n<PERSON>: where is th future of Zim if police officers do nt obey High court orders? they refused 2 release human rights lawyer, <PERSON>\nBlogger Sir <PERSON> observed:\nWe are well aware of the Machiavellian tactics of the law enforcement agents and other state institutions who have everything to fear from lawyers who represent their clients without fear or favour and insist on full compliance with the law and constitutional safeguards.\nThese retrogressive forces believe that such tactics will intimidate <PERSON> and have a chilling effect on other human rights lawyers who continue to soldier on bravely in representing all manner of human rights defenders who have suffered serious rights violations. There is a misguided belief that by attacking lawyers, as well as their clients, positive forces who believe in a new professional way of behaving will be cowed, and civil society engagement in issues of human rights and democracy will be destroyed.", "424" ], [ "Zimbabwe Prime Minister <PERSON>’s Controversial Wedding · Global Voices\nAfter Zimbabwean Prime Minister <PERSON> went ahead with his wedding on 15 September, 2012, despite attempts to bar it by an estranged former partner, netizens of course took to Twitter and Facebook to express their thoughts.\n<PERSON>'s former lover sought the court's order to stop the wedding on the ground that the two of them were married. He abandoned plans for a civil wedding and went ahead with a traditional one; Zimbabwe's customary laws allow for polygamy.\nReactions on Facebook\nOn Facebook, <PERSON> posted:\nU can not stop the wind from blowing or either the time from moving, loca u failed dismally to stop the weding, <PERSON> [Tsvangirai] is brand no wonder the commander in chief is now supportng him..\n<PERSON> with <PERSON> cutting the wedding cake at at the Glamis Arena. Photo used with permission from nehandaradio.com\n<PERSON> wrote:\nif u love 2people @the same time,choose the 2nd one ,bcoz if u really loved the 1st one,u wldnt have fallen 4 the 2nd……(he <PERSON> did that,dn fight it gal,he followed his heart)\n<PERSON> added:\nGod knows the way wait n see the good things coming soon in your life madam, never give up coz of criticism but smile God loves you.\n<PERSON> said of the Prime Minister’s other “jilted lover”:\nshould not force to be loved. For love without mutual respect is hollow plus its high she resist to be used as a porn for political expediency.\n<PERSON> advised:\nRe-build your life and forget about <PERSON> [Tsvangirai]!\n<PERSON> posted:\nShe must visit <PERSON> [Popular Nigerian preacher].", "424" ], [ "Ane mhepo dzake [she is possessed]\n<PERSON> said:\ngold digger/ image tarnisher/ mutumwa [agent]\n<PERSON> prayed:\nOh Heavenly Father help this lady who had reduced Zimbabwean courts to be kangaroo courts.\n<PERSON> commented:\nleave the pm (Prime Minister <PERSON> dont tell me you have not been having an affair since <PERSON> dumped you. If you did it was adultary indeed.\nReactions on Twitter\n<PERSON>: Some people can't read PR trends. At #Locardia level the plot was working. Enter the SA woman & the overdose turned #<PERSON> into victim.\n<PERSON>: Is <PERSON> fit to be the leader of women? What are we feeling about all his love scandals as the electorate of Zimbabwe?\n@percyzvomuya: Ah, <PERSON>, why snub one woman for another? Why not do a couple of weddings? One in Harare, another in Bulawayo & make everyone happy?\n@Zanele_20: Wonder how long <PERSON>'s wedding is goin to last this time.", "424" ], [ "Zimbabwe: Bloggers not happy with the Coalition Government · Global Voices\nZimbabwean bloggers are unhappy with the way things are turning out within the coalition government between <PERSON> and <PERSON>. The reactions are a mixture of distrust of <PERSON> ad disappointment in the policy approaches of the MDC.\nThe blog Living Zimbabwe sees no point in <PERSON>'s remaining as Prime Minister if he is powerless. Supporting Mrs <PERSON>'s statement that “unless <PERSON> shows leadership now, it is going to be a waste of time having an inclusive government anyway”, the blogger says:\nNonetheless, what Mrs. <PERSON> had to say about the GNU was straight to the point and a fact that cannot be ignored. If <PERSON> cannot protect <PERSON>, what is the point of him being Prime Minister?\nMost bloggers are frustrated by the lack of visible change in the lives of ordinary Zimbabwe. Kubatana blog, for instance, has a photo of a Zimbabwean reading the state-owned daily newspaper, The Herald, from 11 March, exactly a month after <PERSON> was sworn in, with the headline: Harare Runs Out Of Water – Again.\nMostly in the firing line is <PERSON>, the new MDC minister in charge of telephone and Internet services (ICT Minister) in Zimbabwe. <PERSON> again reproduces a letter sent to the state-controlled telephone company, TelOne, which <PERSON> is now in charge of and which is threatening legal action against the company for their “high-handedness”\nZimbabwe's collapse of Internet services, cut off by Intelsat because TelOne had not paid its debts, also elicited biting responses from the blogosphere.\nPeace Love and Happiness blog has a post entitled, “Zimbabwe: Minister of Information and Technology, Pull Up Your Socks.” In it, the blogger says:\nIt has been a month since <PERSON> was sworn in as Minister of Communications and Technology and by now we expect him to have made inroads towards the improvement of the telecommunications industry or at least made a tour of all the TelOne telecommunications exchange control rooms so that he familiarises himself with how the company operates but he hasn't done that. If he had done that he would have been informed that TelOne bills that are red in arrears and he would have sorted that problem.", "424" ], [ "The word that is out among Zimbabweans at the moment is that <PERSON> is very good at talking as an opposition member and very weak when it comes to walking the talk.\nOn <PERSON>'s Zimbabwe Blog,in an article entitled: Is <PERSON> an Incompetent, Drooling and Clueless Minister, the new MDC minister is blamed for following discredited policies from ZANU PF, such as price controls on mobile phone charges:\nLast week, Comrade Minister <PERSON> announced that mobile phone charges were too high in Zimbabwe (which they are) and he was going to send a directive to mobile phone companies to reduce their charges drastically. So, we are back to price controls, which everyone, including the resident madman at the corner of First St and <PERSON> as well as street kids, knows does not work. ZANU PF tried it and service suffered as a result. Infrastructure collapsed. Because profit margins are a function of the market, and not a result of a minister's say-so. It is an elementary concept, really, and I wonder how the MDC fail to grasp it.\nWhat on earth has possessed <PERSON>? I ask again.\nWith power and water cuts continuing, this week the world should not be surprised to hear of more riots by soldiers. Most of them are failing to access their US$100 from the banks as promised by the Inclusive Government:\nThere is chaos in Harare today and you should not be surprised to hear later on that soldiers have gone on the rampage again.\nFirst street is absolutely choked with soldiers, policemen, teachers and other civil servants who are failing to access their US$100 salaries. They have been trying since Friday and it clear this morning on First Street that some of them have slept at the banks waiting for them to open. There are blankets and long jackets spread on the pavement, where the civil servants are sitting waiting for the money to get to the banks.\nThere is still a long way to go before things change in Zimbabwe, is the common consensus, but most bloggers seem to think we have started badly, especially considering the concessions the MDC are making to ZAU PF in terms of policy, an area the Coalition Agreement gives them (the MDC) sole control over.", "830" ], [ "Intrigue and Drama as Malawians Await Election Results · Global Voices\nIn some polling centres in Malawi, lines were so long people couldn't see ahead. Photo by <PERSON>. Used with permission.\nIn a bizarre twist for a country in Sub-Saharan Africa, a governing party is accusing an opposition party of having rigged the election.\nUnofficial results in Malawi's elections for president, members of parliament and ward councillors show the incumbent President Dr. <PERSON>, Malawi's and southern Africa's first female president, losing by wide margins and two opposition candidates neck and neck in the running.\nMalawians flocked to polling centres across the country on Tuesday, 20 May, 2014 for the vote. In much of the country voting went on smoothly, but in a number of centres things did not go as planned. In some centres people lined up from 4 a.m. and waited into the afternoon without voting. Anger spilled over into rage, with one centre being set on fire and cast ballots being destroyed in others.\nPeople had hoped that by Thursday, 22 May they would know who had won the elections, but things have taken a dramatic turn.\nA polling centre in Malawi burns. Photo by <PERSON>. Used with permission.\nAs results started trickling in on Tuesday night, <PERSON> took an early lead and Malawian social media went into overdrive. There was an overwhelming sense that he would win the election, even with only 23 percent of the votes counted. There were calls for <PERSON> to concede defeat and for the Malawi Electoral Commission to declare <PERSON> the winner.", "830" ], [ "Pundits started propounding opinions as to why <PERSON> had won and the other three had respectively lost.\n<PERSON> is the younger brother of late President <PERSON> who died suddenly on 5 April, 2012, in his third year of his second five-year term. <PERSON>, his vice president, had fallen out with <PERSON> Democratic Progressive Party and had formed her own party, the People's Party. After initial attempts by <PERSON> inner circle to subvert the constitution and make his brother <PERSON> the president, <PERSON> was sworn in and became Malawi's forth president, finishing the remaining two years from <PERSON> term.\n<PERSON>'s two years has been characterised by scandals, culminating in the uncovering of massive fraud dubbed “cashgate” that reached all the way to her office. A much-awaited opinion poll by Afrobarometer showed <PERSON> leading, followed by Malawi Congress Party candidate Dr. <PERSON>, and <PERSON> coming a distant third.\nOn Thursday morning, <PERSON> called the press to her official residence Kamuzu Palace where she issued a statement but did not take questions from the media. Blogger <PERSON> posted the statement on his blog. In the president's own words:\nIt has come to my attention that there some serious irregularities in the counting and announcement of results in some parts of the country and the People’s Party has presented specific details of these irregularities to the Malawi Electoral Commission\nShe alluded to fears that the electoral commission's communication system had been tampered with. She listed five irregularities, one of which was:\nUsing information technology to block communication devices of some monitors, and thereby limiting the monitors’ ability to effectively carry out their duties.\nTweeting the briefing was journalist <PERSON>, who reported the president's rigging allegation:\nPres <PERSON> says her party has evidence that election has been rigged and this has been submitted to Mec #Malawivote2014\n— <PERSON> (@suzgokhunga) May 22, 2014\nThe president repeated the allegation in a BBC Focus on Africa interview on Thursday night, putting the blame unequivocally at the electoral commission. The People's Party, of which Dr. <PERSON> is the leader, sought a court injunction to stop Malawi Broadcasting Corporation TV and Zodiak Broadcasting Station from announcing incoming election results from polling centres. The High Court rejected the application, according to a Nyasa Times report.\nIn another press conference later in the day, the Malawi Electoral Commission rejected claims that the computer system could have been hacked into. The Nation newspaper tweeted the press conference and quoted the MEC Chair Justice <PERSON> as saying:\n<PERSON>: “The issue of hacking, we are hearing it from the PP. Its not true, this allegation is not true”.", "830" ], [ "Can Zimbabwe handle the coronavirus amid a collapsing health care system? · Global Voices\nA health worker points out what few drugs he has left in his stores in a health center, Mazoe, Zimbabwe, April 22, 2009. Photo by <PERSON> / AusAID via Wikimedia Commons CC BY 2.0.\nCheck out Global Voices’ special coverage of the global impact of COVID-19.\nAs the government of Zimbabwe confirms the first COVID-19 casualty in the country, many Zimbabweans have questioned Zimbabwe's capacity to handle a public health pandemic of this magnitude.\nThe nation's fragile health care system combined with its poor record of internet access has citizens on high alert — and already grieving.\n<PERSON>, 30, succumbed to complications from the coronavirus on the morning of Monday, March 23, 2020, at Harare Wilkins Infectious Diseases Hospital, where he was admitted after showing symptoms.\n<PERSON> was popularly known for his explainer video series, “State of the Nation with Zororo.” He was the son of a prominent businessman, <PERSON>.\nThe Minister of Health and Child Care, Dr <PERSON> has confirmed the death of <PERSON>, who was the second person to test positive for Covid-19 in Zimbabwe.@GNyambabvu @EMupoperi @JoshMunthali @nickmangwana @MoHCCZim @lizmaggz @samaita44 pic.twitter.com/XIqHLiezR2\n— ZBC News Online (@ZBCNewsonline) March 23, 2020\n<PERSON> wrote on Twitter, “let us pause and reflect”:\nMr <PERSON>, the son of Mr <PERSON> has passed on. MHSRIEP. I have just learned of this tragic loss of life due to the virus. A giant with so much potential has fallen. Corona is real. Let us pause and reflect. Life is too precious.\n— <PERSON> (@mmawere) March 23, 2020\n<PERSON> is the second case of coronavirus reported by the Minister of Health and Child Care <PERSON> last week.\n<PERSON> announced the first confirmed case was a British national who resides in Victoria Falls. The 38-year-old male had traveled to Manchester, England on March 7 and traveled back to Zimbabwe on March 15 from Manchester, via South Africa.\nUpon arrival, the patient went into self-quarantine on the advice of <PERSON>, according to The Chronicle.", "424" ], [ "However, after developing “severe respiratory distress,” he was admitted to Wilkins Hospital, where he tested positive for the virus.\nWith two confirmed cases as of March 26, according to WHO, Zimbabweans have no choice but to brace themselves for potential disaster.\nCan Zimbabwe handle coronavirus?\nOn Wednesday, Zimbabwe's doctors and nurses went on strike to protest a lack of personal protective equipment (PPEs) necessary to treat patients with the highly contagious virus.\nEven before the coronavirus crisis reached Zimbabwe, its health care system was collapsing, and families have been expected to provide their own gloves and clean water for basic treatment in health care facilities, according to Time magazine.\nDoctors and nurses had only returned to work in January after a four-month strike to demand higher salaries and improved working conditions, according to Time.\nPresident <PERSON> last week issued an announcement banning gatherings of more than 100 people in an effort to slow the spread of the virus. <PERSON> also ordered the closure of schools, colleges and universities on Tuesday.\nTwitter user <PERSON> asked why there wasn't more “realistic discourse” about COVID-19:\nWhy are we not having a realistic discourse about #COVID19 in Africa- the first fatality in Zimbabwe died gasping for air, doctors on strike as no protective gear, no water in hospitals. People who stay at home have no income and no food\n— <PERSON> (@rashida_abbferr) March 25, 2020\n<PERSON> , a human rights advocate in Zimbabwe, wrote a Facebook post on March 23, sharing her concerns about Zimbabwe's state of unpreparedness:\nI am concerned about the state of unpreparedness that our country is in. A friend of mine battling to save lives in UK while at risk said the Covid Beast is real. I see my fellow citizens in denial that this can happen to us. No one is immune. The cities and towns are buzzing with life. Business as usual. What signs do we need? People are dying. Are we seriously waiting to be told to stay at home.", "424" ], [ "Tanzania’s President Fires 10,000 Civil Servants Over Forged Qualifications · Global Voices\nTanzania's President <PERSON> addressing a crowd during the 2017 May celebrations. Press photo from State House.\nOn the eve of May Day, a day where the world pauses to honour its workers, the government of Tanzania shamed thousands of civil servants in the country.\nOn April 28, President <PERSON> ordered the immediate firing of almost 10,000 civil servants after an investigation found that some government workers had been occupying their positions with forged qualifications.\n“They are thieves like any other thieves,” <PERSON> was quoted as saying. “They could be jailed for seven years as the law says.”\n#Today‘s editoon #TheCitizenToday pic.twitter.com/W3Jak3P1sg\n— The Citizen Tanzania (@TheCitizenTZ) 1 de mayo de 2017\nThis purge comes a year after the government found that it was losing billions of shillings annually to tens of thousands of “ghost workers.”\nThe report, which looked at verifying the authenticity of 450,000 government employees’ qualifications, found that district municipalities led in the number of civil servants with forged certificates at 8,716. They were followed by other government-run institutions like the Sokoine University of Agriculture which had 33 people with fake qualifications and the Tanzania Railway Cooperation with 24.\n‘Safi sana’ news\nIt didn't take long for the internet to share its two shillings on the news.\nSome people expressed some sympathy for the sacked civil servants, asking <PERSON> to give those with fake certificates strength.\n<PERSON> tu hayo majina yanayopita huko Whatsapp but hii ishu inaumiza sana kimaisha na kisaikolojia#Mungu awatie nguvu wenye#VyetiFeki\n— Dr <PERSON> (@emgeni) 29 de abril de 2017\nJust take note of the names circulating on WhatsApp but something like this is heart-breaking and can affect someone psychologically.", "424" ], [ "May God give strength to those with fake certificates.\nOthers were cracking jokes about the whole thing.\n<PERSON>, <PERSON>, <PERSON>, <PERSON>\n— Charles Mtekateka (@mtekatekajr) April 29, 2017\nStarting next Tuesday, if you see a public official not going to work, playing with the kids at home, don't ask too many questions!\nGenerally, the news received a lot of “poa sana” (very cool) “safi sana” (very nice) as people are pleased that some action is being taken over the issue. Even former President <PERSON> came out publicly supporting <PERSON>'s move, saying the decision was “overdue.”\n‘…they love to give jobs to their family members…’\nOf course, there were people who took the matter less lightly.\n<PERSON> went on Twitter arguing for an independent commission to adjudicate the matter.\nKuwepo na Tume Huru itakayopokea malalamiko ya wafanyakazi #vyetifeki . Serikali can not judge its own case. @MariaSTsehai @humanrightstz\n— <PERSON> (@hyphym) May 1, 2017\nThere should be an independent commission that will listen to the complaints of workers with fake certificates. The government cannot judge its own case.\nMeanwhile, one opposition party, Alliance for Change and Transparency (ACT), tweeted that although they supported the government's drive against fake certificates in the civil service, they questioned whether the exercise went far enough.\nJambo la Pili lisilokuwa sawa, madai ya Waziri @AngellahKairuki kuwa mchakato wa uhakiki wa vyeti haujawagusa wanasiasa na wateule wa Rais\n— <PERSON> ✋ (@ACTwazalendo) April 30, 2017\nThe second issue that's not right are the statements by Minister <PERSON> that the process of verifying certificates does not implicate politicians and government appointees.\nThe party went on to suggest that the decision amounted to the government protecting some of its appointees.\n<PERSON> wa kisiasa katika zoezi la uhakiki wa vyeti ni ushahi wazi jinsi serikali inavyohaha kuwalinda baadhi ya wateule wa Rais pic.twitter.", "424" ], [ "Cyclone leaves trail of devastation in Zimbabwe and throughout Southern Africa · Global Voices\nCyclone Idai devastates Zimbabwe, Malawi, Mozambique and South Africa with massive flooding, rocks, and mudslides. Image of flooding in Mozambique, shared widely on social media.\nTropical Cyclone Idai has left a devastating trail of destruction and death after sweeping through Mozambique, Malawi and Zimbabwe in Southern Africa.\nAt least 162 people have lost their lives so far in the devastating storm across region. In Mozambique, the city of Beira has been nearly entirely wiped out.\n#UPDATE A cyclone that slammed into Mozambique last week has damaged or destroyed 90 percent of the city of #Beira, the Red Cross says, as the death toll in the country and neighbouring Zimbabwe rose to 157 https://t.co/vZYLj71n4A #CycloneIdai pic.twitter.com/LiWR2MWIsY\n— AFP news agency (@AFP) March 18, 2019\nThis is a map of where the cyclone hit:\nSofala, Manica, Zambezia and Inhambane provinces in #Mozambique have been hardest hit by #CycloneIdai\nInitial reports indicate significant damage to Beira and surrounding areas, including destroyed houses.https://t.co/dAj2RpQKar pic.twitter.com/1eTv9wdmso\n— OCHA Southern & Eastern Africa (@UNOCHA_ROSEA) March 16, 2019\nAt least 89 people have died in Zimbabwe alone, amid fears of a higher figure, in Manicaland's Chimanimani district, located 406 kilometers east of Zimbabwe's capital, Harare, as homes and bridges were swept away by a tropical storm that began on Friday.\nSome people still attempt to cross this bridge in Chimanimani #Zimbabwe despite the danger\nCyclone #Idai pic.twitter.com/sVC6dDW6jr\n— harumutasa/aljazeera (@harumutasa) March 17, 2019\nMore than 300 people are missing according to the government.\nThe United Nations in Zimbabwe said that more than 8,000 people have been affected by the flooding in the eastern parts of the country.\n“Sadly lives have been lost and properties destroyed,” United Nations Zimbabwe said in a tweet:\n#UN in #Zimbabwe is on the ground in Chimanimani district and other areas to support ~8,000ppl affected by flooding & landslides caused by #Cycloneidai. Sadly, lives have been lost & properties destroyed.", "206" ], [ "Please take heed to SMS & media alerts by Civil Protection\n— UN Zimbabwe (@UNZimbabwe) March 16, 2019\nAccording to the government, Cyclone Idai hit the Ngangu Township are in Chimanimani the hardest where most lives were lost. Over a hundred houses were damaged by falling mud and rocks.\nThe storm originated in the Indian Ocean and led to a torrential rainstorm which commenced in Mozambique on Thursday, with wind speeds of about 160 kilometers per hour, reportedly causing ocean waves of up to 9 meters high.\nWe have no idea how much damage Cyclone Idai has caused – human and otherwise – especially in the area around Beira. Roads are blocked, power lines are down, cell phones are offline. It could be much worse than we know so far. https://t.co/sOpkTvbZ6W\n— <PERSON> (@simonallison) March 18, 2019\nThe police and military have been deployed to assist in the evacuation of victims.\nVisibility, according to the Information ministry, has significantly improved and this will help airforce helicopters to evacuate more people.\nThe Airforce of Zimbabwe and the Zimbabwe National Army are on the ground saving lives.\nPresident <PERSON> has deployed an Elite Team from the ZDF, CIO & other security forces to deliver aid & rescue victims of Cyclone Idai\nMilitary Engineers will also assist in rebuilding pic.twitter.com/5D35YO7RRx\n— <PERSON> (@KMutisi) March 17, 2019\nLocal government minister <PERSON> said that bodies are currently being seen floating in rivers and nothing much can be done at the moment.\nRoads, bridges and telephones are currently cut off and hundreds of homes destroyed.\nCountry director for the International Red Cross (IRC) Zimbabwe <PERSON> said the IRC teams in Zimbabwe are trying to reach communities affected by the cyclone but the infrastructure damage is severe and the teams couldn't reach Chimanimani or Chipinge.\n“Urgent road repairs in progress so we will try again in the morning,” said <PERSON>.", "424" ] ]

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[ [ "Colonizing the galaxy by slow boating reality check\nHumans like to explore and seem to have an almost instinctual need to expand. After spreading throughout the solar system and even into the Oort Cloud they decided that humanity should follow the robot probes out into the galaxy.\nWithout FTL, but having discovered a form of artificial gravity and having experience creating space habitats, they create a number of generation ships. These massive structures are initially given a population and crew of 30,000, with room to expand to 50,000, and each one has all the tools and manufacturing capabilities to make more generation ships and space habitats, along with the ability to terraform a planet.\nStrapping on a few large meteors with ice, minerals and other things they may need in an emergency, these ships slowly make their way to the nearest solar system. Slow being a little less than half the speed of light, thanks to getting a very large boost as they start their journey.\nOnce there, they get to work making comfortable habitats for the now increased and cramped population using the resources of the system.", "199" ], [ "They spend several decades there, creating a working system of habitats and making any repairs that are needed on the generation ships. After a century or two the generation ships, possibly a few new ones as well, get crewed by people who want to travel and move onto the next solar system to do the same thing all over again. Eventually the fleet splits into two and each one does the same thing, eventually splitting again, and again and again.\nIf they find a planet that looks like it can be terraformed, a planet with no life, or only the most basic of bacteria which is wiped out, they get to work making the planet livable for the people who want to have a sky over their head. Any planets with multicellular life is carefully studied by probes, but left otherwise alone because the risk of contamination, allergies, etc, are too great for the ships, and terraforming them will destroy the ecosystem.\nIs this a realistic way to colonize and explore the universe?", "197" ], [ "I foresee hollow protoplanets!\nSince this species develops in a free-fall environment within a space-based cloud of gas littered with resource-rich/-poor asteroids, the first major structures will be built on the asteroids for mining operations. Individuals rarely want to travel long distances to get to work (long is, of course, relative in space), so housing will be built on the same asteroid as the mining facility. As the facility grows, it will need access to more resources, so either the company will start another mining facility or haul other asteroids to an existing one.\nClumps of asteroids then become the foundation for larger settlements, which attract more attention, more business, and more inhabitants, which bring in more asteroids to support the growing population.\nIndependent facilities will produce a similar effect, though in this case \"clumps\" will be individual asteroids connected via trade routes. The collections will attract attention, which brings in business, inhabitants, and more facilities. To prevent unwanted drifting, asteroids would be tethered together to emphasize established trade and transport routes.\nIn either situation, the city is developing in three dimensions, expanding roughly evenly in all directions.", "788" ], [ "This produces a spherical structure, with the oldest buildings at the center.\nTethers and nuts and bolts should be quite capable of holding things together; after all, they do quite well under constant gravitational stress from Earth.\nThe common architecture is going to be something much like what's on the ISS. There's no real down direction, so doors can be in any flat surface, possibly even in cones, corners, or hemispheres. In the case of asteroid clusters, paths of travel will be delineated by the structures themselves, where walls and solid connectors work together to create tunnels through the whole structure. In the case of asteroid collections, paths of travel will, in the macroscale, be defined by the inter-asteroid tethers, while local conditions will be like those for asteroid clusters.\nThe tethers and pipes used to connect structures and asteroids can double as infrastructure. Tethers can provide electricity and fiber optic cable. Pipes supply fresh water and remove waste.\n(All of this ignores the viability question of your scenario, which I am in no way capable of answering.)", "99" ], [ "What large scale strategies would an interstellar nation use to conquer another interstellar nation?\nI'm working on a science fiction setting for a game. I'm trying to write a setting that focuses on man-operated war machines in sight range combat. Everything ranging from fighters to mechs to capital ships would be used and have logical reasons within the setting to steer combat towards that approach.\nOne of the factions are a group of colonies that had declared independence from Earth decades ago and had managed to win it. These colonies since declared themselves a new interstellar nation with a strong economy, but their military power has always been limited by their low relative population compared to other interstellar nations. Their military doctrines lean heavily into getting the most out of the individual in their military forces and maximizing the survival rates of their pilots and crews (think large war machines with small crew/pilot counts and lots of armor.)\nOver the decades since, interest in reclaiming these outer colonies would change with each election cycle, sometimes sparking one of many short lived wars to reunite humanity under one rule.", "46" ], [ "At best, they would manage a stalemate, at worst, they would be pushed back.\nI'm trying to figure out what the strategy of the Earth military would be in trying to re-establish control over these colonies. I imagine landing troops wouldn't really work on a planetary scale as they would need pretty much need an occupation force far larger than would be sensible to maintain. Though a strategy of precise military strikes on the ground might work?\nI know that taking points of interest might be a factor, as well, factories that produce war machines, shipyards and the like. Anything that might help them establish a foothold in enemy territory.\nI should also mention that robotic and other autonomous combatants are specifically outlawed by treaties signed by multiple interstellar nations that I'm still working on the details of. A robot/drone army isn't an option for them.\nThe only real strategy I can think of is blockading planets and taking control of the system gates to force a world into submission. FTL between systems utilizes artificial wormholes generated by massive gates that are expensive to produce, so it would be easy to control travel to and from a system by shutting off gates.\nArmed incursions might only be limited to things like seizing factories, military bases and shipyards to limit the colony's ability to fight back while under that blockade.\nWhat are some other strategies that might come into play in this scenario?", "46" ], [ "Space gate traffic control problem\nA civilization uses the sci-fi staple of space gates to get around between systems. These gates, for our purposes, are big, round and very much not transparent; think the star gates but huge or the gates in the X universe of games. You can't see though them, we will assume they have a frequency shadow some what like deep water.\nThe civilization has a huge range of ships, some tiny like cars and some colossal ships that only just fit through the gates. A system is doing really well, traffic is up a huge amount on last year, but there is a problem. The accident rate is also up.\nHow do you stop ships popping out of the gate directly in front of another ship, causing an accident? However, efficiency is very important. We don't want to limit the gates to one ship at a time in each direction. However, if one of the really big ships is coming through it is necessary to stop all craft from the other side.", "302" ], [ "It is also important that ships keep a minimum safe distance between each other. When a ship enters it leaves in the same place on the other side. The ship has to be entirely inside the portal before it starts coming out the other side. Travel time is near instant once inside the portal. Ships enter and exit at the same speed.\nBear in mind that it is hard for the two halves of the gate to talk to each other, deep water is hard to transmit though (though not impossible). I would like to not break the <PERSON> rate limit here. Some other method of communication between the sides is possible. I had a slightly crazy idea of using ping pong balls to signal a ships impending arrival while thinking about this.\nShips not following the proper protocol will be dealt with by law enforcement, for \"Reckless endangerment of life in control of a ship\" or some such law.\nI'm looking for a system that provides the best bi-directional through put of ships and doesn't cause any one to sit in a queue for hours on either side of the gate.", "537" ], [ "What observable traits set the MilkyWay apart from other Galaxies?\nIn a short story, Earth's humanity dies off to a plague and a few thousands years later a space faring race plants a new seed of humans in attempt to restore what civilization used to be.\nThe Earth is effectively the same, though biomes may change and a couple thousand years of wild evolution have passed (so a wild dog might look a bit different but it's still clearly a canine). The method of \"planting the seeds of civilization\" is apparently instantaneous to the humans, as if one day, everyone just woke up as if they had just gone to sleep normally the day before. At that point, the seed planters take their leave and observe from afar without interaction. (The story spans hundreds of years as they observe)\nIt's just one big city, outfitted with the tools and resources necessary to farm, process, and produce what a population of that size would normally consume. The humans have been granted the know how on how to operate the machines and build a sustaining civilization. Satelittes and cell phones don't exist but they would later be reinvented. Their next generation being the first humans that actually would need to learn how to walk, talk, read.", "302" ], [ "Their parents are somewhat programmed to work together in building a sustainable \"start\" to the civilization (even if they aren't exactly aware as to why) and would come off as very literal and set in their ways while their children are more creative, looking at the world in increasingly philosophical ways.\nOther than the knowledge of the world around them and how to survive though, these humans do not have a living past in memory. They don't have a notion of \"where did we come from\" and this first generation largely doesn't care. Their children though ask such questions, using the tools and technologies we have now and in the near future to rediscover the universe outside of the Earth. This generation spawning a renascence of invention and discovery in the absence of war and while crime is still a distant concept while everyone's needs are met. Some conflicts arise between competing theories and discoveries.\nWithout a history, polytheist stories (where the milky way got it's name in reality) or previous inspirations, they need something to name it. What observable traits set the Milkyway apart from other galaxies? Also keeping in mind they don't have a distant probe to view it from anywhere but Earth. They can see distant galaxies while they are deciding on a name.\nThis naming period may last a few years as these fresh explorers catch up to our current IRL astronomical knowledge and begin sending out orbital telescopes similar to our own.\nTypical DM brain, I can make a world, but fail to find a good name.", "693" ], [ "Living on a giant banana world\nIn my story, which should be taken entirely seriously, mankind encounters a region of space occupied mostly by giant exo-householdobjects.\nThat is, planet sized kettles, saucers, teacups, cutlery, etc. There is even a giant <PERSON> branded teapot, because this is how serious a story it is. They orbit around perfectly ordinary stars of various sizes.\nThe protagonists are going to spend a significant amount of time stuck on a giant banana while observing a solar system with many such objects. They are mostly incredibly impractical people - philosophers, theologians and so on - with a small cohort of ships engineers and tradesmen, as well as a rapacious mine manager called <PERSON> who only cares about the giant silverware.", "322" ], [ "They're very well supplied with everything they could want except the means to get offworld.\nLeave aside the problem of gravity trying to make the banana into a sphere - assume that either the banana is mostly made of a nearly infinitely strong material when you drill much beneath the peel, or better still, that gravity is excluded from operating within it and only begins at the surface (albeit with all the mass of the banana still contributing). With a sunlike star, what combination of orbital distance and rotational motion can make this pungent, ethyne laced world in the sweet spot of being inhabitable but periodically very uncomfortable or dangerous?\nI'm specifically interested in: 1) and main) What problems are generated by rotation of the banana and what if any rotational motions are amenable to life at least over a few square kilometres while still being a damned nuisance?\nSo, it needs a few square kilometres that have sort-of earth temperatures and pressures. I'll say -20 to 80 deg C temperature, and 0.3 to 3 bar pressure, with possible intermittent exceptions.\nI'm guessing depending on the axis of rotation, there are going to be areas that are uninhabitably hot/cold. I'd like to place their town in the middle of the banana on the concave side, unless there are any serious objections or better suggestions.\nFor obvious reasons, answers need only stand up to limited scrutiny.\nOrbiting fruit worlds and kettles raise such serious theological, philosophical and anthropological problems that the eggheads that are on it are only going to notice that their lives are in danger when the engineers are banging on their doors warning of the impending 30 day shadow that will cause temperatures to drop to dangerously low levels and they need to put their entire libraries in buggies or local flying craft and relocate.\nI welcome anyone raising problems relating to atmospheric composition or ground instability that are likely to arise as the banana ripens, although I am not short of ideas in this department...unlike, you know, how these people can survive for 20s without freezing or burning or being thrown off the surface.", "921" ], [ "Approximately the same time as it has taken the original to arrive at the same age and physical condition, obviously!\nYet this may not quite be acceptable from a plot point of view, so here's a few pointers on reducing that time frame, contingent on the use of the clone.\nSpare parts\nYou don't actually need a full clone for this, it should be possible to graft the organ to be replaced onto a bio-compatible host and with growth/rate accelerators you'd be looking at several months to years. Some organs are problematic: the brain, for instance (we simply don't know enough about the interconnections between all the neurons except that these interconnections are partly created through learning by the individual), but also muscles as muscles need a work out to be compatible with the individual receiving the spare part. On the bright side, you can require some re-validation therapy and it may be advantageous to use a younger version of an organ.\nRejuvenation\nThe practice where a much younger clone is used as a replacement body when old age becomes a hindrance. This requires a mind transfer technology which presumably fixes the neuron and neuron interconnection problem. There is plenty of time to grow a body (say, twenty years) and the clone body does not need much exercise and can be kept unconscious during the entire growth cycle. A period of up to a year of exercising the new body after the mind transfer (the old mind has to adapt to the much younger body) is probably acceptable as well.\nReplacement\nThe practice where a clone body is offered as a replacement in case of accidents or after being murdered.", "335" ], [ "Again, this requires a mind transfer technology in addition to regular mind recordings as a backup to restore onto the blank slate. This is one of the more difficult use cases as it requires the body to be grown fairly fast, say less than five years, while keeping it a blank slate. Another problem is to copy the physiological impact of the environment on the new body, i.e. scars, wear and tear, and so on. Without this the clone will not have an identical or even similar look! Again an adjustment period of the recorded mind to the new body of a year is acceptable.\nReplication\nThis is the use case where the genotype of successful individuals are copied to augment (or supplant, whatever the plot is) the general population. The problem here is to copy the environment and learning processes too as the phenotype is the determinant of success, not the genotype on its own. However, decades to grow and learn a clone into an individual are permissible, as each copy will be an individual, albeit very similar to another copy.\nOther uses\nThere are probably other very creative uses of clones but the main things to consider are:\n* in how far does the phenotype (result of environment and genetics) of the clone need to match the original? A blank slate is much easier than a fully trained individual.\n* how much time do you have to prepare the clone in advance? If you need anything less than a couple of years, I'd seriously look into biological 3D printing and infusing the 3d printed cells with the DNA from the host.", "335" ], [ "Would this setup of a terraformed moon hold up?\n[Edits added in italic]\nBACKGROUND A few thousand years from now the moon has become one of many habitable places in the solar system. Economy, constant growing knowledge and human will made drastic technological progress possible.\nEarly on people sat up moon bases and mines and flourishing trade quickly drew more and more investors. In some hundret years domes and cities of domes rouse on the moons surface, as resources were extracted from underneath, experiments and modifications were made in a variety of fields, and AI became deeply engaged in the maintainenace of all of this. People made business out of the delivery of resources from and to wherever they were needed in the solar system. During the course of many centuries humanity learned to terraform effectively and domes became temporary startup solutions. Terraforming is not cheap, but the moons location as easy-to-access trading spot in the solar system (earth-to-moon-to-mars / mars-to-moon-to-io / Kuiper belt-to-moon-to-earth etc) made it rich and thriving for progress.\nPeople have for long preserved earth's genetic heritage for multiple reasons and spread it to the other habitable places, in adapted forms. The moon, closest and therefore a perfect second hard drive, becomes over the course of a millenia swamped with flora and fauna. Modification in order to preserve is morally totally fine, but still not completely discovered. People, plants and animals feel fine (enough) to not suffer from living on the moon.\nThis future moon acquired the following conditions\n* Energy is provided by mega structures (have to look into that), as well as provided by nuclear fusion with helium 3 mined on place, but there is a lot of solar energy around, especially from tall towers in more or less permanent sunlight on the poles. Waste-to-energy became also pretty efficient, and there are some neat setups that use waste for other productions, like biochar, and some waste heat is converted into energy as well.\n* A thick, breathable atmosphere, rich on water vapour, is kept up with imported resources (AI and complex structures keep it dense, balanced and maintained).", "922" ], [ "It keeps the temperatures in range and protects from space threats.\n* An artificial magnetic field (AI is my cheap answer on that, too), to help keeping the atmosphere.\n* Enough water to create lakes and seas with a depth of 10 meters, and more brought by daily delivery (just like the 1950s milk man, only a business some million times bigger, travelling from the Kuiper belt to the planets).\n* 29 earth-day long days (14,5 days day time, 14,5 days night time, a sunset about 1 day long)\n* 13 days per year. The four seasons as we know them are about 3 days long each.\n* Temperature differences caused by the long \"nights\" and \"days\", ranging from -90 C to +70 C in the most extreme places. These provoke strong winds and thunder storms. The average temperature is +25 C in summer and -20 C in winter.\n* Habitable places, close to the poles and further off from the equator, experience -5 C during \"summer nights\" and up to -50 C during \"winter nights\", and the days warm up to +45 C during \"summer days\" and +5 C on \"winter days\". Just like on earth now, no one lives long without a house of some kind, but you can be outside for a limited amount of time with the right clothing.\n* [Comment: deep-freezing is apparently something to avoid, going to look into that]\n* There are mainly fast travelling clouds, clearing off in the middle of the day in spring, summer and autumn (after about 8-11 earth-days) when air starts to get heated up by the sun, and clouding in during or after sunset when the temperatures drop again, often resulting in thunder storms. Rain and snow falls mainly during the night.\n* Since there is only a 6th of earth gravity rain falls slower and in thicker drops. Hail is a common threat, balls get bigger, but the impact is a 6th softer. It almost always freezes during night.\n* Soil is made from 1/8 th compost or manure, 1/8th biochar and 6/8th gravel (trust me, this works on earth, too). Biochar can be produced on place as soon as there is vegetation. Not the entire surface will be soiled (ha!), only about 3-5%, with an average depth of 30 cm (trees get 80cm, but most plants need less). The manure and compost comes mainly from people and livestock on the moon.", "591" ] ]

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[ [ "Inconsistent? hamiltonians for a scalar field in the presence of a classical source\nConsider a real scalar field \\begin{equation} \\phi(x)=\\int\\frac{d^3p}{(2\\pi)^3}\\frac{1}{\\sqrt{2E_p}}\\left(a_pe^{-ip\\cdot x}+a_p^{\\dagger}e^{ip\\cdot x} \\right). \\end{equation}\nIn Chapter 2 of <PERSON>, right after Eq. 2.64, we have the form of the hamiltonian for a real scalar field coupled to a classical source $j(x)$: $$1) \\qquad H =\\int \\frac{d^3p}{(2\\pi)^3}E_p\\left(a_p^{\\dagger}-\\frac{i}{\\sqrt{2E_p}}\\tilde{j}^*(p) \\right)\\left(a_p+\\frac{i}{\\sqrt{2E_p}}\\tilde{j}(p) \\right),$$ where $\\tilde{j}(p)=\\int d^4y e^{ip\\cdot y}j(y)$.\nOn the other hand, the hamiltonian which describes such a system is given by \\begin{equation} 2) \\qquad H=H_0-\\int d^3x j(x)\\phi(x). \\end{equation}\nI want to see that these two expressions for the hamiltonian are indeed equivalent.", "281" ], [ "By expanding the first one we obtain \\begin{eqnarray} H&=&\\int \\frac{d^3p}{(2\\pi)^3}E_p a_p^{\\dagger}a_p+\\int \\frac{d^3p}{(2\\pi)^3}i\\sqrt{\\frac{E_p}{2}}\\left(a_p^{\\dagger}\\tilde{j}(p) -a_p\\tilde{j}^(p)\\right)+\\int\\frac{d^3p}{(2\\pi)^3}\\frac{|\\tilde{j}(p)|^2}{2}\\ &=&H_0+\\int \\frac{d^3p}{(2\\pi)^3}i\\sqrt{\\frac{E_p}{2}}\\left(a_p^{\\dagger}\\tilde{j}(p) -a_p\\tilde{j}^(p)\\right)+\\langle 0|H| 0 \\rangle. \\end{eqnarray}\nSince $\\langle 0|H| 0 \\rangle$ is a constant term we can ignore it. Therefore, \\begin{equation} H=H_0+\\int \\frac{d^3p}{(2\\pi)^3}i\\sqrt{\\frac{E_p}{2}}\\left(a_p^{\\dagger}\\tilde{j}(p) -a_p\\tilde{j}^*(p)\\right). \\end{equation}\nNotice \\begin{eqnarray} \\int \\frac{d^3p}{(2\\pi)^3}i\\sqrt{\\frac{E_p}{2}}\\left(a_p^{\\dagger}\\tilde{j}(p) -a_p\\tilde{j}^*(p)\\right)&=&\\int \\frac{d^3p}{(2\\pi^3)}i\\sqrt{\\frac{E_p}{2}}\\left(\\int d^4x j(x)\\left(a_p^{\\dagger}e^{ip\\cdot y}-a_pe^{-ip\\cdot y} \\right)\\right)\\ &=&\\int d^4x j(x)\\left[\\int \\frac{d^3p}{(2\\pi)^3}i\\sqrt{\\frac{E_p}{2}}\\left(a_p^{\\dagger}e^{ip\\cdot x}-a_pe^{-ip\\cdot x} \\right)\\right]\\ &=&\\int d^4x j(x)\\dot{\\phi}(x). \\end{eqnarray} That would leave us with the expression \\begin{equation} 1) \\quad H = H_0+\\int d^4x j(x)\\dot{\\phi}(x).", "374" ], [ "Does the commutator between the total derivative term of a symmetry generator and a quantum field always vanish?\nI am trying to understand the following derivation in <PERSON> section 28.2 as to how Noether Charges can be thought of as symmetry generators.\nWe start with the definition of $Q$ (for simplicity let's consider a single scalar field):\n$$ Q=\\int{d^3x}\\frac{\\delta L}{\\delta\\dot{\\phi}}\\frac{\\delta\\phi}{\\delta\\alpha}.\\tag{28.5} $$ Using the fact that $\\frac{\\delta L}{\\delta\\dot{\\phi}}(x)=\\pi(x)$ and $[\\pi(x),\\phi(y)]$=$-i\\delta^{(3)}(\\overrightarrow{x}-\\overrightarrow{y})$ we find $$ [Q,\\phi]=-i\\frac{\\delta\\phi}{\\delta\\alpha} $$ which is the desired result for $Q$ to be a symmetry generator (from my understanding).\nHowever this derivation neglects the possibility of a total derivative term in the current. For full generality we need to modify the charge expression to $$ Q=\\int{d^3x}\\frac{\\delta L}{\\delta\\dot{\\phi}}\\frac{\\delta\\phi}{\\delta\\alpha}+\\Lambda^0.", "818" ], [ "$$\nThus I would expect the relation to be modified to $$ [Q,\\phi]=-i\\frac{\\delta\\phi}{\\delta\\alpha}+\\int{d^3x[\\Lambda^0,\\phi]}. $$\nMy question is: for every example I have seen in QFT so far, $[\\Lambda^0,\\phi]=0$ and so the formula $[Q,\\phi]=-i\\frac{\\delta\\phi}{\\delta\\alpha}$ seems to hold. Is this true in general, and if so, is there a proof of this? Without this missing element I feel that the derivation in <PERSON> is incomplete, as many currents have boundary terms.\nTo give an example, consider the super-current in the free Weiss Zumino Model, which contains the following total derivative term $$ \\Lambda^\\nu=-\\theta\\sigma^\\mu\\bar{\\sigma}^{\\nu}\\psi\\partial_{\\mu}\\bar{\\phi} + \\theta\\psi\\partial^{\\nu}\\bar{\\phi}+\\bar{\\phi}\\bar{\\theta}\\partial^{\\nu}\\phi $$ We see that $$ [\\Lambda^0,\\phi]=[-\\theta\\sigma^\\mu\\bar{\\sigma}^{0}\\psi\\partial_{\\mu}\\bar{\\phi} + \\theta\\psi\\partial^{0}\\bar{\\phi},\\phi]=[-\\theta\\sigma^0\\bar{\\sigma}^{0}\\psi\\partial_{0}\\bar{\\phi} + \\theta\\psi\\partial^{0}\\bar{\\phi},\\phi]=[-\\theta\\psi\\partial_{0}\\bar{\\phi} + \\theta\\psi\\partial_{0}\\bar{\\phi},\\phi]=0 $$ where we used the fact that $\\partial_0\\bar\\phi$ is the conjugate momentum to $\\phi$, and $$ [\\Lambda^0,\\psi]=0 $$ as none of the terms in the current contain the conjugate momentum to $\\psi$ ($\\pi=-i\\sigma^{0}\\bar\\psi$).\nIs there a fundamental reason why this should always be true for any theory and any current?", "818" ], [ "Thanks for your hints so far. The question was to some extend already discussed here: (https://physics.stackexchange.com/questions/109343/eigenstate-of-field-operator-in-qft). <PERSON>, I give a more verbose and down-to-earth answer to my question. There is also a remark why I was confused first...\nEigenstates of the annihilation field as classical states\nWe assume a real valued scalar quantum field $A(x)$ of the form (neglecting normalization)\n\\begin{equation} \\hat A(x) = \\int \\hat a^{*}(k)e^{ikx} \\, d^{3} k + \\int \\hat a(k)e^{-ikx} \\, d^{3} k = \\hat A_c(x) + \\hat A_a(x) \\end{equation}\nwhich is split in a creation and annihilation part.", "669" ], [ "We are looking for a eigenstate $| \\psi \\rangle$ of the annihilation operator $\\hat A_a(x)$. Such a state is the tensor product of single mode coherent states: $| \\psi \\rangle = \\otimes_k |\\alpha(k) \\rangle_k$, since every single mode state in the tensor product is an eigenstate of the corresponding annihilation operator $a(k)$ with eigenvalue $\\alpha(k)$. Hence $\\hat A_a(x) | \\psi \\rangle = \\int d^{3} k' e^{-ik'x} \\hat a(k')\\otimes_k |\\alpha(k) \\rangle_k =\\int d^{3} k' e^{-ik'x} \\alpha(k') \\otimes_k|\\alpha(k) \\rangle_k = \\psi(x) | \\psi \\rangle$\nwith the eigenvalue $\\psi(x) = \\int d^{3} k e^{-ikx} \\alpha(k)$. The eigenstate $| \\psi \\rangle$ is also called coherent and can be written as \\begin{equation} | \\psi \\rangle = \\otimes_k e^{\\alpha(k) \\hat a^{}(k)} |0 \\rangle = e^{\\int d^{3}k \\alpha(k) \\hat a^{}(k) } |0 \\rangle = e^{\\int d^{3}x \\hat A_c(x) \\psi(x)} |0 \\rangle = e^{\\int d^{3}x \\hat A(x) \\psi(x)} |0 \\rangle \\end{equation} The first part of the above equation is more or less by definition true (refer to single mode coherent states) the second part is valid since all $\\hat a^{*}(k)$ commute, the third part is valid since (Fourier expansion of field and eigenvalue)\n\\begin{equation} \\int d^{3}x \\hat A_c(x) \\psi(x) = \\int \\int d^{3} k d^{3} q \\, \\int e^{i(k - q)x} d^{3}x \\, \\alpha(q) \\hat a^{} (k) = \\int d^{3} k \\alpha(k) \\hat a^{}(k) \\end{equation}\n(The space integral results in a delta function $\\delta(k-q)$). The last part of the defining equation above is true since $\\hat A_a |0 \\rangle = 0$ and hence $e^{\\int d^{3}x \\hat A_a(x) \\psi(x)} |0 \\rangle = 0$.\nCorollary: $\\langle \\psi |\\hat A_a(x) |\\psi \\rangle = \\langle \\psi |\\psi(x)|\\psi \\rangle = \\psi(x) \\langle \\psi |\\psi \\rangle = \\psi(x)$.", "66" ], [ "The Lagrangian for a massive vector field (without sources) has the form\n$$ L = -\\frac{1}{4}F_{\\mu\\nu}F^{\\mu\\nu} + \\frac{1}{2}M^{2}A_{\\mu}A^{\\mu}$$\nand is not gauge invariant due to the mass term. The eq.s of motion are\n$$\\partial _{\\mu}F^{\\mu\\nu} + M^{2}A^{\\nu} = 0$$ and by deriving a second time\n$$\\partial_{\\mu} A^{\\mu} = 0$$\nthat is not a gauge-fixing. Instead it arises dynamically and reduces the d.o.f. from 4 to 3. In the electromagnetic case (massless vector fields) once you fix the gauge you have an additional residual gauge condition that reduces the d.o.f.", "298" ], [ "from 3 to 2. The e.o.m. can be solved in the momentum space $$A^{\\mu}(x) = \\frac{1}{4\\pi^{2}} \\int \\frac{d^{3}k}{2\\omega}(e^{ik\\dot x}\\epsilon^{\\mu}(\\mathbf{k}) + c.c.)$$\nWhat I think <PERSON> wants to say is that in the massive case you can always choose a reference frame on the particle and so the time component of the polarization vector $\\epsilon^{\\mu}$ became redundant.\nWhen I think of three possibilities for spin-1, I think {+1,0,−1}. When I think >of a spin-1 \"vector state,\" I think the three positions in the vector represent {+1,0,−1}and not {,,}\nMaybe you are talking about the $z$-component of the spin. For $\\frac{1}{2}$-spin it can also point in 3 directions, in fact there is the quantum number $helicity$ that is the projection on the direction of motion of the spin.\nHere I understand that due to special relativity, is a function of , but since >I don't see the connection to the polarization states, I am missing the >relationship to the amplitude. I believe <PERSON> when he cites this dependence of the amplitude, but where does it come from?\nIn an analogous way to the scalar field, from the expression of the $A^{\\mu}(x)$ you can see that the creation and absorption amplitude are proportional to the polarization vectors.\nHow <PERSON> is able to conclude immediately that it is \"fixed proportional to ${}−\\frac{{}_{}}{^{2}}$?\nFor the Lorentz invariance $$\\sum \\epsilon_{\\nu}^{(a)}(k) \\epsilon_{\\lambda}^{(a)}(k) = -g_{\\nu\\lambda}A(k^{2})+k_{\\nu}k_{\\lambda}B(k^{2}) $$ You can multiply the previous for $k^{\\nu}$ and applying $k^{\\mu}\\epsilon_{\\mu}^{(a)} = 0$ you find $$0 = -k_{\\lambda}(-A(k^{2})+k^{2}B(k^{2})) \\iff B(k^{2}) = \\frac{A(k^{2})}{m^{2}}$$ Also in the case $\\nu = \\lambda$ for the completeness relation $$\\sum \\epsilon_{\\nu}^{(a)}(k) \\epsilon_{\\nu}^{(a)}(k) = -1 = A(k^{2})$$", "346" ], [ "Break down of time independent perturbation formula of quantum mechanics in quantum field theory\nThe following paragraph is from <PERSON> Sec 4.2.1\nUsing OFPT we would calculate the energy shift using\n$$\\Delta E_n = \\langle\\psi_n\\rvert H_{int} \\rvert \\psi_n\\rangle +\\sum_{m,m \\ne n} \\frac{\\rvert \\langle\\psi_n\\rvert H_{int} \\rvert \\psi_m\\rangle \\rvert ^2}{E_n-E_m}$$\nThis is the standard formula from time-independent perturbation theory. The basic problem is that we have to sum over all possible intermediate states $\\rvert \\psi_m \\rangle$, including ones that have nothing much to do with the system of interest (for example, free plane waves). It is still true in field theory that there are only a finite number of states below any given energy level $E$, so that as $E \\to \\infty$, $\\frac{1}{E-E_n}\\to0$.", "669" ], [ "The catch is that there are an infinite number of states, and their phase space density goes as $\\int d^3k \\sim E^3$, so that you get $\\frac{E^3}{E-E_n}\\to \\infty$ and perturbation theory breaks down. This is exactly what <PERSON> found.\nI have 3 doubts in the above text\n$1$.What does <PERSON> mean with the states which has nothing to do with our system of interest? Why does it cause us some uneasiness to sum over states that have nothing to do with our system of interest, where he gives an example of plane waves but perturbation does not regard whether the state has little or large impact in the summation. We just add all the terms mechanically to get the change in energy. For example, say we have $\\psi_1,\\psi_2,\\psi_3$ when we do calculation of $\\Delta E_1$ we have two terms in second-order $\\frac{\\rvert \\langle\\psi_2\\rvert H_{int} \\rvert \\psi_1\\rangle \\rvert ^2}{E_2-E_1}$,$\\frac{\\rvert \\langle\\psi_3\\rvert H_{int} \\rvert \\psi_1\\rangle \\rvert ^2}{E_3-E_1}$ now suppose latter term comes from the wavefunction($\\psi_3$) which has nothing to do with our system but still we have thrown it in our summation to get right result because that's how we derived the formulae for $\\Delta E_n$ the set of all wavefunction used in summation must be complete.\n$2.$ It doesn't matter whether there are finite number of states below any given energy $E$ since we are summing over all states we have to even add those states which have much higher energy than $E$ so what does he want to convey when he says as $E \\to \\infty$, $\\frac{1}{E-E_n}\\to0$.\n$3.$ What is phase space density? And how $\\int d^3k \\sim E^3$? If I assume $H$ to be of form $H_{int}=\\int {\\frac{d^3k}{{(2 \\pi)}^3} \\omega_k(a_k^{\\dagger}a_k + \\frac{1}{2})}$ then ${\\langle\\psi_n\\rvert H_{int} \\rvert \\psi_m\\rangle} \\sim (const)\\int d^3k \\omega_k \\sim E$ since $E=\\hbar \\omega_k$ and we are summing over all possible $k$ which will lead to an exponent of 2 rather than 3 in $\\frac{E^3}{E-E_n}$ though the sum will diverge in both the case.", "669" ], [ "How to derive Eq. 6.21 in <PERSON>?\nI'm reviewing <PERSON>'s chapter on path integrals and am having trouble understanding how he arrives at formula 6.21:\n$$\\left<0|0\\right>{f,h}= \\int \\mathcal{D}q \\,\\mathcal{D}p \\, \\exp \\left[i \\int{-\\infty}^{+\\infty} dt \\Big( p\\dot{q}-(1-i\\epsilon)H+fq+hp \\Big) \\right]. \\qquad (6.21)$$\nHe gives a wordy explanation that sounded like it made sense at first before I thought about it too hard, but on further thought, I just don't see his logic.", "916" ], [ "He begins with the following equation, which I can accept:\n$$\\left<0|0\\right>{f,h}=\\lim\\limits{t'\\to-\\infty}\\lim\\limits_{t''\\to+\\infty}\\int dq'' dq' \\psi_0^*(q'') \\left\"_{f,h} \\,\\,\\psi_0(q')\\,, \\qquad (6.19)$$\"\nwhere the $\\psi_0$'s represent the ground state of the Hamiltonian (without the $-i\\epsilon$). Then he introduces the trick of changing $H$ to $(1-i\\epsilon)H$, which I am also willing to accept. With this change, he shows that\n$$\\lim\\limits_{t'\\to-\\infty} \\left| \\, q',t'\\right> = \\psi_0^*(q') \\left|0\\right>$$ $$\\lim\\limits_{t''\\to+\\infty} \\left< \\, q'',t''\\right| = \\psi_0(q'') \\left<0\\right|.$$\nThis is the end of his mathematical derivation—he then uses two paragraphs to explain how this all means that \"we can be cavalier about the boundary conditions on the endpoints of the path\" and jump to Eq. (6.21).\nCan someone please fill in the mathematical gaps here? The issue I'm having is that the above fact seems to only bring us in a circle:\n$$\\left<0|0\\right>{f,h}=\\lim\\limits{t'\\to-\\infty}\\lim\\limits_{t''\\to+\\infty}\\int dq'' dq' \\psi_0^*(q'') \\left\"_{f,h} \\,\\,\\psi_0(q') \\qquad (6.19)$$\"\n$$ =\\int dq'' dq' \\psi_0^(q'') \\bigg[ \\psi_0(q'') \\left<0\\right| \\bigg] \\bigg[ \\psi_0^(q') \\left|0\\right> \\bigg] \\,\\,\\psi_0(q') \\qquad$$\n$$ =\\left<0|0\\right> \\int dq'' \\left|\\psi_0(q'')\\right|^2 \\int dq' \\left|\\psi_0(q')\\right|^2 \\qquad\\qquad\\qquad\\quad$$\n$$=\\left<0|0\\right>\\qquad\\qquad\\qquad\\qquad\\qquad\\qquad\\qquad\\qquad\\qquad\\,\\,\\,$$", "916" ], [ "So the aim is to solve the equation $(\\Box+m^2)\\phi(\\vec{x},t)=0$ for $\\phi$ ($m=0$ in <PERSON>'s example, but we'll leave it in). Note that (as <PERSON> writes) $$(\\Box+m^2)\\phi(\\vec{x},t)=(\\partial_t^2-\\vec{\\nabla}^2+m^2)\\phi(\\vec{x},t)=0\\tag{(1)}$$ Something you will get used to is flipping between differential operators in position space and their form in Fourier space. The Fourier conjugates of $\\Box$ and $\\Delta=\\vec{\\nabla}^2$ are namely $-p^2$ and $-\\vec{p}^2$, respectively.", "418" ], [ "To see how this works, consider the field expressed in terms of its $\\vec{p}$-space Fourier conjugate, which we will call $a_\\vec{p}(t)$: $$\\phi(\\vec{x},t)=\\int\\frac{d^3\\vec{p}}{(2\\pi)^3}a_\\vec{p}(t)e^{i\\vec{p}\\cdot\\vec{x}}.$$ Insering this into eq. 1 then gives \\begin{align} (\\Box+m^2)\\phi(\\vec{x},t)&=\\int\\frac{d^3\\vec{p}}{(2\\pi)^3}(\\partial_t^2-\\vec{\\nabla}^2+m^2)a_\\vec{p}(t)e^{i\\vec{p}\\cdot\\vec{x}}\\ &=\\int\\frac{d^3\\vec{p}}{(2\\pi)^3}(e^{i\\vec{p}\\cdot\\vec{x}}\\partial_t^2a_\\vec{p}(t)-a_\\vec{p}(t)\\vec{\\nabla}^2e^{i\\vec{p}\\cdot\\vec{x}}+m^2a_\\vec{p}(t)e^{i\\vec{p}\\cdot\\vec{x}})\\ &=\\int\\frac{d^3\\vec{p}}{(2\\pi)^3}(\\partial_t^2+\\vec{p}^2+m^2)a_\\vec{p}(t)e^{i\\vec{p}\\cdot\\vec{x}}\\ &=0 \\end{align*} So we find that the Fourier coefficients for each $\\vec{p}$ are solutions to the conjugate equation to (1): $$(\\partial_t^2+\\vec{p}^2+m^2)a_\\vec{p}(t)=0$$ which should be familiar as the differential equation for simple harmonic motion, solved by $a_\\vec{p}(t)=a_\\vec{p}e^{-i\\omega t}$ where $\\omega=\\sqrt{\\vec{p}^2+m^2}$ and $a_\\vec{p}$ is constant in time (but of course depends on $\\vec{p}$). The final step is to realize that $\\phi^\\dagger(\\vec{x},t)$ is also a solution to (1) (just take the Hermitian conjugate of both sides), so we arrive at the full general solution $$\\phi(\\vec{x},t)=\\int\\frac{d^3\\vec{p}}{(2\\pi)^3}\\left(a_\\vec{p}e^{-ipx}+a^\\dagger_\\vec{p}e^{ipx}\\right)$$ with $px=\\omega t-\\vec{p}\\cdot\\vec{x}$.", "281" ], [ "First of all, I remember <PERSON> is discussing about global U(1) in the case of superfluid. By $U(1)$ we mean that that both Hamiltonian and Lagrangian are invariant under $\\phi\\rightarrow e^{i\\theta}\\phi$ transformation.\nI think he mentioned that what he is doing in that section is called \"integrate out\" high energy fluctuations (fields.)\nThe goal here is---to study excitations around (classical) ground state (with <PERSON>'s notations $\\phi=\\sqrt{\\rho}e^{i\\theta}$), $$ \\phi_0=\\sqrt{\\rho_0}e^{i\\theta_0}, $$ where $\\phi_0$ and $\\theta_0$ correspond to the ground state.\nComments:\n1. Note that this classical ground state is asymmetric because it dose not obey the same symmetry, $U(1)$ of the Lagrangian.\n2. If one write down a self-consistent bosonic theoy in a not hand-wavy way, he will find that tuning the chemical potential (which is correspond to $\\rho$ in above) can obtain the transition between different phases. And for the same reason, for some range of chemical potential, one can have symmetry-breaking phase---superfluid phase in our case. Otherwise, one would get a trivial phase with symmetric ground state with no degeneracy.\nBased my own experience of using AZee's book as textbook in QFT course, I prefer to derive everything in detail, independently, with my notations.", "976" ], [ "Thus I'll slight change notations from here.\nTo be more quantitative, we will apply the language of Lagrangian for non-relativistic non-interacting bosons: $$ \\mathcal{L}=i \\Phi(x)^\\dagger\\dot{\\Phi}(x)-\\frac{1}{2m}\\nabla\\Phi(x)^\\dagger\\nabla\\Phi(x)+\\mu\\Phi(x)^\\dagger\\Phi(x), $$ where $\\mu=ng$ is the chemical potential and $n$ is the particle density of the ground state. We can further include interaction term which triggers the symmetry breaking $$ \\mathcal{L}=i \\Phi(x)^\\dagger\\dot{\\Phi}(x)-\\frac{1}{2m}\\nabla\\Phi(x)^\\dagger\\nabla\\Phi(x)+\\mu\\Phi(x)^\\dagger\\Phi(x)-\\frac{g}{2}\\big(\\Psi(x)^\\dagger\\Phi(x)\\big)^2\\nonumber\\ =i\\Phi(x)^\\dagger\\dot{\\Phi}(x)-\\frac{1}{2m}\\nabla\\Phi(x)^\\dagger\\nabla\\Phi(x)-\\frac{g}{2}\\big(n-\\Phi(x)^\\dagger\\Phi(x)\\big)^2+\\text{constant}. $$ To see the Goldstone modes, we can use polar coordinates to decoupled the amplitude and phase fields, $$\\Phi(x)\\equiv\\sqrt{\\rho(x)} e^{i\\theta(x)}$$. Then we have $$ \\mathcal{L}=\\frac{i}{2}\\dot{\\rho}-\\rho\\dot{\\theta}-\\frac{1}{2m}\\big[\\frac{1}{4\\rho}(\\nabla\\rho)^2+\\rho(\\nabla\\theta)^2\\big]-\\frac{g}{2}(n-\\rho)^2, $$ where $\\frac{i}{2}\\dot{\\rho}$ can be ignored since it's total derivative. In order to find the minimum of this Lagrangian, we can take derivative with respect to $\\rho$, set it to zero and get $\\rho_{min}=0$ as minimum This vacuum value has degeneracy under global $U(1)$ symmetry which will be broken if we pick out a particular vacuum---$\\theta_0$. Fixing the phase of the ground state as $\\theta_0$ is the same at every point in space and can take any value.\nBy <PERSON>'s theorem, breaking a continuous symmetry, global (or local with extra subtleties), will lead to emergence of Goldstone bosons.", "804" ] ]

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[ [ "How does the strong form of the PCP theorem imply the inapproximability of Max-XORSAT?\nTheorem 11.4 For any constant $\\delta > 0$, every problem in NP has probabilistically checkable proofs of length poly($n$), where the verifier flips $O(\\log n)$ coins and looks at three bits of the proof, with completeness $1-\\delta$ and soundness $1/2+\\delta$.\nMoreover, the conditions under which <PERSON> accepts are extremely simple - namely, if the parity of these three bits is even.\nThis theorem has powerful consequences for inapproximability. If we write down all the triplets of bits that <PERSON> could look at, we get a system of linear equations mod 2. If <PERSON> takes his best shot at a proof, the probability that <PERSON> will accept is the largest fraction of these equations that can be simultaneously satisfied. Thus even if we know that this fraction is either at least $1-\\delta$ or at most $1/2+\\delta$, it is NP-hard to tell which. This implies that it is NP-hard to approximate Max-XORSAT within any constant factor better than $1/2$.\nFirst, I don't think it can be as simple as just checking that the parity is even. <PERSON> could just make <PERSON> accept anything by handing him a proof of all zeros, and make him reject anything with a proof of all ones. Surely the parity must instead equal some value that <PERSON> computes along the way.\nFurther, It's not a priori clear to me that <PERSON> would select every triplet with equal likelihood. If that wasn't the case, wouldn't it be possible for a no-instance to yield a Max-XORSAT formula where more than $1/2+\\delta$ of the clauses can be satisfied even though <PERSON> accepts with probability less than $1/2+\\delta$?\nLet's take a degenerate case as an example. <PERSON> asks <PERSON> to help him decide whether a given sequence of $n$ bits $\\mathbf{b}$ is all ones - $\\mathbf{b=1}$ for short. This problem is trivially in NP. And <PERSON> clearly doesn't need <PERSON>'s help.", "768" ], [ "But he can go out of his way to use it anyway. Here's what they do:\nFirst <PERSON> gives <PERSON> a PCP $\\mathbf{x} \\in {0,1}^n$ (let's assume $n \\gg 3$). Then <PERSON> checks if $\\mathbf{b=1}.$ If it is, he checks that $x_1 \\oplus x_2 \\oplus x_3 = 1$ holds in <PERSON>'s PCP. Otherwise, he checks either $x_1 \\oplus x_2 \\oplus x_3 = 1$ or $\\overline{x_1} \\oplus \\overline{x_2} \\oplus \\overline{x_3} = 1$ (note that these can't both be satisfied) with equal probability 0.45. Or with probability 0.1 he checks $x_i \\oplus x_j \\oplus x_k = 1$ for a uniformly random triplet.\n<PERSON> can thus convince <PERSON> that $\\mathbf{b=1}$ by giving him, for example, the proof consisting of all ones. But if $\\mathbf{b\\neq1}$ there's no proof that <PERSON> accepts with probability greater than 0.55. This gives PCP's with completeness $1-\\delta$ (indeed we also have completeness 1) and soundness $1/2+\\delta$ where $\\delta = 0.05$.\nNow what's the Max-XORSAT formula corresponding to $\\mathbf{b\\neq1}$? Well, <PERSON> could look at any triplet $x_i, x_j, x_k$ as well as $\\overline{x_1},\\overline{x_2},\\overline{x_3}$. So presumably it's the conjunction of all those triplets when XORed together. All but one of these clauses can be satisfied. So the fraction is very close to one. But that's nowhere near the probability that <PERSON> will actually accept.\nPS: We need a PCP tag.", "768" ], [ "After some more thought here is my own attempt at a solution:\nAssume for contradiction that the depth $d$ isn't $\\Omega(\\log \\log n)$. Then it must be that\n$\\forall C,N:\\exists n > N: d < C \\lg \\lg n$.\n(Base 2 is an arbitrary choice for the logarithm.)\nIn particular if $C = \\frac 1 2$ then\n$\\forall N: \\exists n > N: 2^{2^{2d}} < n$.\nAt this point the Switching Lemma is required. The Switching Lemma is stated in The Nature of Computation as follows:\nConsider a circuit with $n$ inputs $x_1,...,x_n$ consisting of a layer of OR gates which feed into a single AND gate, where both types of gates have arbitrary fan-in. Now suppose that we randomly restrict this circuit as follows. For each variable $x_i$, with probability $1-n^{-\\frac 1 2}$ we set $x_i$ randomly to true or false, and with probability $n^{-\\frac 1 2}$ we leave it unset.", "743" ], [ "For any constant $a$, if there are $O(n^a)$ OR gates, then with probability $1-o(n^{-a})$ the resulting circuit can be expressed as a layer of a constant number of AND gates, which feed into a single OR gate.\nThe Switching Lemma is symmetric with respect to AND and OR. So every time the Switching Lemma is applied the top two layers are switched and the second and third layer can then be merged into a single layer leaving a circuit of depth $d-1$. Thus after applying the Switching Lemma $d-2$ times the circuit has depth $2$ remaining.\nApplying the Switching Lemma one last time no longer reduces the depth of the circuit but does leave a circuit that only depends on a constant number of inputs. (This follows from details of the proof of the Switching Lemma.)\nAt the same time the number of remaining unset variables is\n$\\sim n^{\\frac{1}{2^d}} > (2^{2^{2d}})^{\\frac{1}{2^d}} = 2^{\\big(\\frac{2}{\\sqrt 2}\\big)^{2d}} = 2^{2^d}$.\nAnd since a previous result established that Parity isn't in $AC^0$, we know that $d$ and for that matter $2^{2^d}$ eventually exceeds any constant.\nIf we were then to set those variables on which the circuit still depends, we'd arrive at a constant circuit computing Parity with some variables still unset, which yields a contradiction.\nAlso note that the width remained polynomial since the Switching Lemma increases it by a constant factor $m$ each time it is applied. So the width is multiplied by\n$m^{d-1} < m^{\\frac{1}{2} \\lg \\lg n} = (\\lg n)^{\\frac{1}{2} \\lg m} = poly(n)$.\nHence $d = \\Omega(\\log \\log n)$.\nI want to point out however that this proof is fairly out of my personal comfort zone. So I don't want to make any guarantees.", "743" ], [ "Is a <PERSON>-Levin reduction a <PERSON> reduction?\nMy understanding is that <PERSON> many-one reductions are more general than <PERSON> many-one reductions, and that <PERSON> many-one reductions must allow for the number of certificates for a problem $A$ reduced to $B$ to be recovered from a single oracle call giving the number of certificates for $B$.\nSo, what exactly is a <PERSON>-Levin reduction? Quoting this paper \"Witness Encryption and its Applications - https://eprint.iacr.org/2013/258.pdf\n\"We now formally describe our encryption systems. For building them we will assume the existence of a witness encryption scheme for an NP-Complete language L for which there exists a Karp-Levin reduction. We focus on presenting the constructions in this section and defer the proofs to Appendix A.\"\nOther instances of \"<PERSON>-Levin\" reductions can easily be found.\nFrom slide 11 here http://www.cs.rutgers.edu/~szegedy/11596/PCP-1.pdf it seems like a <PERSON>-Levin many-one reduction is just a <PERSON> many-one reduction?\nTo explain why I am uncertain about <PERSON> answer below, and why I'm asking this question, quoting from page 17-4 of the \"Hardness of Approximation\" chapter of the \"Handbook of Approximation Algorithms and Metaheuristics\", a chapter written by <PERSON> (a Godel prize winner for his contributions to the PCP theorem):\n\"Reduction is perhaps the most useful concept in algorithm design. Interesting, it also turns out to be the most useful tool in proving computational hardness [21-23]. When a problem $A$ <PERSON> reduces to $B$, the hardness of $B$ follows form the hardness of $A$. Unfortunately, <PERSON> reduction does not ensure that if $A$ is hard to approximate then $B$ is hard to approximate.", "603" ], [ "For reducing hardness of approximation new definitions are necessary.\nLet $F_1(x, y)$ and $F_2(x', y')$ be functions that are optimized for y and y' (maximized or minimized in an arbitrary combination). Let $OPT_1(x)$ and $OPT_2(x')$ be the corresponding optimums. A Karp-Levin reduction involves two maps:\n1. a polynomial-time map $f$ to transform instances $x$ of $OPT_1$ into instances $x' = f(x)$ of $OPT_2$ [Instance Transformation];\n2. a polynomial-time map $g$ to transform (input, witness) pairs $(x', y')$ of $OPT_2$ into witnesses $y$ of $OPT_1$ [Witness Transformation];\nObserve that the witness transformation goes from $OPT_2$ to $OPT_1$. Let $opt_1 = OPT_1(x)$, $opt_2 = OPT_2(f(x))$, $appr_1 = F_1(x, g(f(x),y'))$, and $appr_2 = F_2(f(x),y')$.\"\nSo <PERSON> answer below appears to only cover the \"[Instance Transformation]\" part of a <PERSON>-Levin reduction, and not the \"[Witness Transformation]\" part, which seems to be interpretable as a way to recover certificates from some problem $A$ in $NP$ reduced to $B$ in $NP$ provided the number of certificates for $B$.\nAm I off the mark here? And how is a <PERSON>-Levin reduction different than a <PERSON> reduction?\nIf there is non-standard terminology, or if definitions are supposed to be \"understood\" depending on whether one is talking about reductions among perhaps counting problems where witness transformations matter, please understand that this is intimidating for someone coming from outside of computer science! People's patience here is very much appreciated.", "603" ], [ "You can use meet-in-the-middle to reduce the running time to $O(n^{\\lceil k/2 \\rceil})$.\nFor simplicity, let me assume that $k$ is even.\nThe idea is as follows:\n* Partition $A$ into two parts.\n* For each part, compute a sorted list of sums of $k/2$ elements from the part.\n* For each $k/2$-sum in the first part, use binary search to find the best $k/2$-sum in the second part which conforms to the constraints.\nAs stated, there are several problems with the idea:\n1. It assumes that the optimal solution contains exactly $k/2$ summands out of each part.\n2. It runs in time $O(n^{k/2} \\log n)$.\n3. It uses $O(n^{k/2})$ memory.\nTo handle the first difficulty, there are several options. We could just repeat the entire algorithm $\\sqrt{k}$ times. Alternatively, there might be deterministic ways to achieve the same goal.", "743" ], [ "Here is a hybrid solution:\n* Randomly partition $A$ into $k^3$ parts $P_1,\\ldots,P_{k^3}$ (anything substantially larger than $k^2$ would work). With high probability, each element of the optimal solution is in its own part.\n* Consider all possible partitions of $A$ into two parts of the form $P_1,\\ldots,P_i$ and $P_{i+1},\\ldots,P_{k^3}$. One of these will contain exactly $k/2$ elements of the optimal solution.\nTo handle the second difficulty, we need to be slightly more careful in implementation. Using merging (the familiar subroutine from mergesort), it should be possible to compute the $k/2$-sums of each part in $O(n^{k/2})$. The final step can be implemented in $O(n^{k/2})$ using a classic two-pointer technique (the first pointer goes up on the first half, the second one goes down on the second half).\nThere are tricks to reduce the memory required from $O(n^{k/2})$ to $O(n^{k/4})$: further divide each part into two sub-parts. You can easily go over all $k/2$-sums in the first part by considering all pairs of $k/4$-sums in its subparts. Binary search on the second part can then be implemented using the two-pointer technique.", "743" ], [ "Interactive proofs for coNP languages proof clarification\nI was reading a paper by <PERSON> and <PERSON>. \"Are there interactive protocols for co-NP languages?\" Information Processing Letters 28 v5 (1988), pp. 249-251. An online version of the paper can be found at http://lance.fortnow.com/papers/files/conpipl.pdf.\nMy question concerns the second part of the proof (the last paragraph), in the case we have a prover which makes $V_i$ accept with probability 2/3: I am not sure why there must exist an oracle query $x$ of length $N_i$ that appears in at most $p_i/2^{N_i}$ computation paths. Shouldn't there be $2^{M_i}$ computation paths where $M_i = poly(N_i)$ is the number of random bits? So then some $x$ must appear in $p_i*2^{M_i}/2^N_i$ paths, which is not clearly small.\nFor reference, I am reproducing the proof below:\nWe want to prove that there exists an oracle A and a language $L \\in \\mathrm{coNP}^A$ such that $L \\not\\in \\mathrm{IP}^A$.\nFor any oracle $A$, let $L(A) = { 1^n : \\text{$A$ contains all strings of length $n$}}$. It is clear that $L(A) \\in \\mathrm{coNP}^A$ for all oracles $A$. We will create $A$ in stages. At each stage we look at some finite set of strings. For each string in this set, we decide whether to include or exclude this string from A. In stage $i$, we choose the set of strings so that $L(A)$ does not have an interactive protocol with verifier $V_i$. Thus, after the construction, $L(A)$ cannot have an interactive protocol and we have proved our statement.\nStage $i$: Pick $N_i$ large enough so $2^{N_i} > 3(N_i)^i$ and no oracle queries of length $N_i$ have been asked in any previous step.", "180" ], [ "Let $p_i = (N_i)^i$. We will determine some strings of $A$ such that either $1^{N_i} \\in L(A)$ and no prover can convince $V_i$ to accept $1^{N_i}$, or $1^{N_i} \\not\\in L(A)$ but there is a prover that will cause $V_i$ to accept. Every time $V_i$ makes an oracle query which hasn't been previously answered, we answer yes.\nIf there aren't any provers $P$ such that $P$ and $V_i$ accept on input $1^{N_i}$ with probability at least 2/3 then we put in the oracle $A$ all strings of length $N_i$ and every other previously unset string that $V_i$ asks about for any prover. This completes step $i$. Note that $V_i$ can only make queries of length less than $p_i$ so will will always be able to find $N_{i+1}$ in step $i+1$.\nOtherwise we have some prover $P$ such that $P$ and $V_i$ will accept $1^{N_i}$ with probability at least 2/3. On any computation path (which is determined by $V_i$'s coin tosses), $V_i$ can ask at most $p_i$ oracle queries of length $N_i$. Since the same number of coin tosses are used during each round, the probability of each computation path is identical. There is some oracle query $x$ of length $N_i$ that appears in at most $p_i/2^{N_i}$ of the computation paths of $V_i$. By the way we chose $N_i$, this means that the oracle query $x$ appears in fewer than one-third of the computation paths of $V_i$. We put all the strings of length $N_i$ except for $x$ in the oracle A, and also place in the oracle every string queried by $V_i$ on every possible communication with $P$. $P$ will convince $V_i$ to accept with probability greater than one-third since more than a third of the computation paths are the same as before. So we are done with step $i$.", "743" ], [ "Proof of PCP theorem\nI am reading the proof of PCP theorem in Proof Verication and Hardness of Approximation Problems. The following paragraph appears in section 3 (page 4), \"Outline of the Proof of the Main Theorem\".\nThe results of these sections show that $NP \\subset OPT (poly(n), 1)$ (Theorem 5) and $NP \\subset OPT (\\log n, poly \\log n)$ (Theorem 8). Theorems 9 and 10 show that the recursion idea applies to these proof systems, and in particular shows the following:\n1. $OPT (f (n), g(n)) \\subset OPT (f (n) + O(\\log g(n)), (\\log g(n))^{O(1)} )$ and\n2.", "945" ], [ "$OPT (f (n), g(n)) \\subset OPT (f (n) + (g(n))^{O(1)} , 1)$.\nThis allows us to conclude that $NP \\subset OPT (\\log n, poly \\log \\log n)$ (by composing two $OPT (\\log n, poly \\log n)$ proof systems) and then by composing this system with the $OPT (poly(n), 1)$ proof system we obtain $OPT (\\log n, 1)$ proof system for $NP$.\nEdit. Composition of verifiers is defined in Probabilistic Checking of Proofs: A New Characterization of NP section 3 (page 13) \"Normal Form Verifiers and Their Use in Composition\".\nLet $r, q, s, t$ be any functions defined on the natural integers. Suppose there is a normal-form verifier $V_2$ that is $(r(n), s(n), q(n), t(n))$-constrained. Then, for all functions $R, Q, S, T$, $$RPCP(R(n), S(n), Q(n), T(n)) \\subseteq \\RPCP(R(n) + r(\\tau), s(\\tau), Q(n) + q(\\tau), Q(n)t(\\tau))$$ where $\\tau$ is a shorthand for $O((T(n))^2)$.\nWhere $RPCP(r, s, q, t)$ is a $PCP(r, s \\cdot q)$ which takes $t$ time to accept of reject after reading the $s \\cdot q$ bits.\nI still don't see how this composition works. Is $OPT(r, q) = RPCP(r, q, 1, q)$ and a normal form verifier? In that case it seems to work, but then just composing $OPT(poly(n), 1)$ with $OPT(\\log n, poly \\log n)$ is enough, so why bother with $OPT(\\log n, poly \\log \\log n)$ or relations $1.$ and $2.$?", "945" ], [ "IP algorithm for finding path in graph\nSuppose for each positive integer $N$, we have a graph $G_N$ with $N$ vertices labelled $1$ to $N$ (so $\\log N$ bits are required to specify a vertex). Suppose we have a PSPACE algorithm to determine whether two given vertices in $G_N$ are adjacent (ie the space used is $P(\\log N)$ for some polynomial $P$). Consider the following decision problem:\nGiven integers $N,M$ and vertices $a,z$ in $G_N$, is there a path of length $\\leq M$ from $a$ to $z$ in $G_N$?\n(the size of the input is $3\\log N+\\log M$ bits). We can answer this problem using the following recursive algorithm:\ndef exists_path(N,M,a,z):\nif M == 0: return a == z\nif M == 1: return are_adjacent(N,a,z)\nfor b = 1 to N:\nif exists_path(N,M/2,a,b) and exists_path(N,(M+1)/2,b,z): return True\nreturn False\nThe recursion depth is $\\log M$, so the space used is $(3\\log N+\\log M)\\log M+P(\\log N)$. In particular the problem is in PSPACE.", "180" ], [ "Since IP=PSPACE, there must be an IP algorithm for this problem. In theory I can follow the proofs on wikipedia to encode the problem as a TQBF problem... but I doubt the result will be pretty.\nIs there an explicit IP algorithm for this problem?\nI'm happy to assume the adjacency problem is actually in P if it makes things simpler.\nNote that we can't just treat the adjacency algorithm as a black box. Indeed fix $k\\in(0,1)$ and consider two possible adjacency functions:\ndef are_adjacent1(N,a,z):\nreturn z == a + 1\ndef are_adjacent2(N,a,z):\nreturn z == a + 1 and a != ceil(k*N)\nThese represent graphs $G_N,G_N'$ where $G_N$ is a path graph and $G_N'$ is the same minus a single edge. Now hand are_adjacent1 to an honest prover and are_adjacent2 to an honest verifier. Since the verifier can only make $O(\\log N)$ calls to the adjacency function, with high probability it will never check the single missing edge, and be convinced that vertices $1$, $N$ are connected in $G_N'$, which is false.", "180" ], [ "Here's something more complicated, which performs $n + o(n)$ comparisons, and achieves an approximately correct list with high probability.\nSuppose you want to partition a set $V$ of $n$ elements into a disjoint union $L \\cup S$ of a set of larger elements and a set of smaller elements, where every $s \\in S$ is bounded above by every $\\ell \\in L$, and where where $# L \\approx \\sigma n$ for some constant $0 < \\sigma < 1$. Then with only a constant (or smaller than constant) probability of failure, we can select $L$ in such a way that it contains all of the $\\sigma n$ largest elements of $V$, together with only a constant (or decreasing) fraction of extraneous elements.\nAlgorithm\n1. Obtain a sample $X$ of $N$ randomly selected elements, for some $0 < N < n$ which we will specify later. Sort them. This takes time $O(N \\log(N))$.\n2. For some parameter $\\delta > 0$, find a pivot $x^\\ast$, chosen to be the $(\\sigma + \\delta/2) N^{\\text{th}}$ largest element of $X$. (If there are multiple elements with the same value, put all of the copies of the value of $x^\\ast$ which precedes the $(\\sigma + \\delta) N^{\\text{th}}$ largest element into $L$; put the rest of the values, including $x^\\ast$ itself, into $S$.)\n3. Compare all of the remaining elements of $V \\smallsetminus X$ to $x^\\ast$.", "743" ], [ "If they are larger, put them in $L$; otherwise, put them in $S$.\nLet $M$ be the set of the $\\sigma n$ largest elements of $V$. We will consider the probability that $L$ contains all of the elements of $V$, but no more than $\\delta n$ additional elements of $V$ beyond that.\nProbabilistic and run-time analysis.\nThe probability that any particular element of $X$ is in $M$ is, by definition, $\\sigma$. In particular, by the <PERSON> bound, the probability that $X$ contains as many as $(\\sigma + \\delta/2)N$ elements of $M$ scales as $$ \\Pr\\biggl[ #(X \\cap M) \\geqslant (\\sigma + \\delta)N \\biggr] ~~\\leqslant~~ \\exp\\Bigl( -\\delta^2 N/2\\Bigr),$$ and that therefore $$ \\Pr\\biggl[ x^\\ast \\in X \\cap M \\biggr] ~~\\leqslant~~ \\exp\\Bigl( -\\delta^2 N/2\\Bigr). $$ Because $L$ is constructed to be all of the values which are larger (or at least succeed) $x^\\ast$ in $V$, it follows that $M$ is a subset of $L$ provided that $x^\\ast \\notin M$. Then, we have $$ \\Pr\\biggl[ M \\not\\subseteq L \\biggr] ~~\\leqslant~~ \\exp\\Bigl( -\\delta^2 N/2\\Bigr), $$ for any $\\delta > 0$. We want more than this, however: we would like the number of extraneous elements in $L$ not to be too large. The expected number of elements in $L$ is going to be $(\\sigma + \\delta/2)n$, but we're interested in the probability with which it is less than $(\\sigma + \\delta)n$, as well as being at least $\\sigma n$. That is, we want to know the probability with which the number of elements is bounded by $\\delta n/2$ from the expected value, which is $$ \\Pr\\biggl[ |# L - \\sigma n | \\geqslant \\delta/2 \\biggr] ~~\\leqslant~~ 2 \\exp\\Bigl( -\\delta^2 N/2\\Bigr). $$ If we want this probability of failure to be at most some value $0 < p < 1$, we then require $$\\begin{equation} p \\geqslant 2\\exp\\Bigl( -\\delta^2 N/2\\Bigr) ~~\\implies~~ N \\geqslant \\frac{2\\ln(2/p)}{\\delta^2}\\;.", "532" ] ]

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[ [ "Fast multiplication of highly structured matrix\nI want to compute a fast matrix-vector product using a matrix $T$ which has a peculiar quasi-Hankel structure. For example, \\begin{equation} T_2= \\left( \\begin{array}{c|ccc|cccccc} a & b & c & d & e & f & g & h & i & j\\\\hline b & e & f & h & 0 & 0 & 0 & 0 & 0 & 0\\ c & f & g & i & 0 & 0 & 0 & 0 & 0 & 0\\ d & h & i & j & 0 & 0 & 0 & 0 & 0 & 0\\\\hline e & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0\\ f & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0\\ g & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0\\ h & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0\\ i & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0\\ j & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 \\end{array} \\right). \\end{equation} \\begin{equation} T_3=\\left( \\begin{array}{c|ccc|cccccc|cccccccccc} a & b & c & d & e & f & g & h & i & j & k & l & m & n & o & p & q & r & s & t\\\\hline b & e & f & h & k & l & m & o & p & r\\ c & f & g & i & l & m & n & p & q & s\\ d & h & i & j & o & p & q & r & s & t\\\\hline e & k & l & o\\ f & l & m & p\\ g & m & n & q \\ h & o & p & r\\ i & p & q & s\\ j & r & s & t\\\\hline k & \\ l & \\ m & \\ n & \\ o & \\ p & \\ q & \\ r & \\ s & \\ t \\end{array} \\right) \\end{equation} Larger matrices $(T_4,T_5,...)$ have the same block structure; in fact, each successive $T_i$ is contained as a partial block of all $T_j,j>i$ (see above examples). All of the unique elements are contained in the first column or row, but the matrix does not possess classical Hankel/Toeplitz/etc.", "490" ], [ "structure typical of fast structured matrix vector multiplication. This matrix arises from a convolution of a certain sort, so I am convinced that the matrix-vector product can be computed in $\\mathcal{O}(N\\log N)$ time or something close rather than $\\mathcal{O}(N^2)$. I'd appreciate the input of others, or potentially helpful references.\nEdit: The block structure is controlled by the parameter $P$ so that the matrix $T_P$ has a $(P+1)\\times(P+1)$ upper left triangular block structure. The $p$th row or column block is of dimension $(p+1)(p+2)/2$.", "945" ], [ "Comparing algorithms for tridiagonal linear systems solution\nBelow there are two algorithms for solving tridiagonal linear systems of the form $$ \\left[ \\begin{array}{ccccc|c} b_1 & c_1 & & & &d_1\\ a_2 & b_2 & c_2 & & & d_2\\ & \\ddots & \\ddots & \\ddots & & \\vdots\\ & & a_{n-1} & b_{n-1} & c_{n-1} & d_{n-1}\\ & & & a_n & b_n & d_n \\end{array} \\right]. $$ I called them Algorithms A and B.", "490" ], [ "Both of them are equivalent to Gaussian elimination, but with important difference in the form of the resulting triangular (bidiagonal) matrix.\nMy main question is: which one of them is more preferrable?\nAlgorithm A is the one that described in Wikipedia and many textbooks, it is called <PERSON> algorithm and is implemented, for example, in Numerical Recipes in some tricky form. Algorithm B is more straightforward and, in my opinion, is more numerically stable in cases when $|b_i|\\gg|a_i|+|c_i|$ . Though I haven't seen Algorithm B in texbooks, note that exactly this algorithm is implemented in the mentioned Wikipedia article, see \"Implementation in Fortran 90\", while \"Implementation in Matlab\" deals with Algorithm A (\"Implementation in C\" in its current state is a mess that does not seem to work at all).", "768" ], [ "When using <PERSON> solvers to solve $\\mathbf A \\mathbf x = \\mathbf b$ systems, singularity in $\\mathbf A$ can be pretty benign as long as $\\mathbf b$ is consistent. Consider applying the conjugate gradient (CG) algorithm to a symmetric positive semidefinite $\\mathbf A$ (singular, but all non-zero eigenvalues still positive). Further assume $\\mathbf b$ is in the range of $\\mathbf A$, and we pick the initial guess to be $\\mathbf x = \\mathbf 0$. Then, the search vector/residual $\\mathbf r = \\mathbf b - \\mathbf A \\mathbf x$ will always be orthogonal to the nullspace of $\\mathbf A$ (because in CG, search vectors/residuals are always drawn by applying $\\mathbf A$ to previous residuals, and this multiplication by $\\mathbf A$ can't generate any component in the nullspace).", "768" ], [ "The algorithm can never \"sense\" the singularity of $\\mathbf A$, and will converge to the (unique!) $\\mathbf x$ such that $\\mathbf A \\mathbf x = \\mathbf b$ and $\\mathbf x \\perp \\mathrm {null}(\\mathbf A)$\nA short demo in matlab:\nclear all\nclose all\n% Form positive semidefinite A.\nN = 10;\n[Q,~] = qr(rand(N));\nD1 = linspace(1,N/2,N/2);\nD2 = zeros(1,N/2);\nD = diag([D1 D2]);\nA = Q*D*Q';\nkappa = cond(A) % infinite/singular\n% Form random b in range(A).\nb = A * rand(N,1);\n% Solve A*x=b using CG.\nx = pcg(A,b);\n% Check properties.\nresidual = norm(A*x-b)\nnullity = norm(x'*null(A))\nSimilar arguments can be made for other <PERSON> solvers, but I can't really speak to \"classical\" iterative solvers (Gauss-Seidel etc) .. I doubt they are as well-behaved.\nThere are preconditioning strategies (deflation) based entirely on this idea: find a basis for the eigenvectors of $\\mathbf A$ that are somehow problematic to the solver, then \"deflate\"/project them out (change the operator such that the corresponding eigenvalues are mapped to zero), then apply the same projection to $\\mathbf b$, and iterate away. For more information about deflation preconditioning (which involves convergence analysis for singular systems), I recommend:\n<PERSON>, <PERSON>, et al. \"A comparison of two-level preconditioners based on multigrid and deflation.\"\n<PERSON>, <PERSON>, and <PERSON>. \"Deflation and balancing preconditioners for <PERSON> subspace methods applied to nonsymmetric matrices.\"", "768" ], [ "Inverse problems in Computational Chemistry: The case of Inverse eigenvalue Problems for molecule structures\nMathematics Background\nAn inverse eigenvalue problem (IEP) is the problem of reconstructing a matrix with a special structure from prescribed spectral data. By structure we mean the pattern of entries that are either zero or nonzero. There are many different types of IEPs with different level of difficulty which depends on the structure of the matrices which are to be reconstructed and the available eigen information. For example consider the following real Jacobi matrix:\n$$ A_n = \\begin{bmatrix} a_1&b_1&0&0&0&0& \\cdots & 0\\ b_1&a_2&b_2&0&0&0&\\cdots&0\\ 0&b_2&a_3&b_3&0&0&\\cdots&0\\ 0&0&b_3&a_4&b_4&0&\\cdots&0\\ 0&0&0&b_4&a_5&b_5&\\cdots&0\\ 0&0&0&0&\\ddots&\\ddots&\\ddots&0\\ 0&0&0&0&\\cdots&b_{n-2}&a_{n-1}&b_{n-1}\\ 0&0&0&0&\\cdots&0&b_{n-1}&a_n \\end{bmatrix} $$\nSuch that $b_i$s are nonzero and $a_i$s may or may not be zero. An IEP about this matrix is this:\nLet $A_i$ be $i$th leading principle submatrix of $A_n$ and let $n$ be an even number, for a given Jacobi matrix $J$ of size $n/2 \\times n/2$ and list of numbers $\\Lambda = {\\lambda_1, \\cdots, \\lambda_n}$, find an $n \\times n$ Jacobi matrix $A_n$ such that $J$ is its minor principle submatrix and $\\Lambda$ is its eigenvalues.\nor\nFor a given list of real numbers $\\Lambda = {\\lambda_1, \\cdots, \\lambda_n }$ and $\\mu ={ \\mu_1, \\cdots, \\mu_{n-1} }$, find a Jacobi matrix $A_n$ such that $\\Lambda$ is its eigenvalues and $\\mu$ is eigenvalues of $A_{n-1}$.\nMany different problems are considered by researchers in many papers.\nBecause graphs are appropriate tools for presenting a matrix structure, many papers concern IEP of graphs.", "945" ], [ "For a given symmetric matrix $A_{n \\times n}$, graph of $A$ is a graph $G=(V,E)$ such that $V = {v_1, \\cdots,v_n}$ and edge ${v_i,v_j} \\in E$ if entry $[A]_{ij} \\neq 0$. In many papers IEP of matrix of graphs (path and broom graph (path graph is actually a symmetric Jacobi matrix), star graph, four different IEPs for paw graph and etc.) are investigated by researchers. Please note that it is also possible to consider IEP of a directed graph, in this case its matrix will not be symmetric anymore.\nWhat I am looking for ...\nAfter a few years of studying IEPs in pure mathematics, I am looking for inverse eigenvalue problems with real practical application. many times, problems are modeled as a matrix and the limits on the problem are moved to the matrix entries or its spectral information and then researchers study the matrix. For example IEP of mass spring system is investigated which is a topic in physics.\nIEP of problems in Computational Chemistry are rarely (or even never) investigated and because many entities and molecules in chemistry are look like some graphs (path or cycle), and graphs can also be modeled as a matrix, hence different types of IEPs may happen there. I ask for any help to introduce some field of studies or references or even cooperation to help me in doing this.\nThanks in advance.", "180" ], [ "After a bit more thought, I think it's actually fairly simple to modify TDMA to deal with arbitrary diagonal offsets:\nForward sweep:\n$$ \\begin{align} c'i & = \\begin{cases} \\cfrac{c_i}{b_i} & ; & i=1,2,\\dots,k \\ \\cfrac{c_i}{b_i-c'{i-k} a_i} & ; & i=k+1,k+2,\\dots,n-k \\end{cases} \\ \\ d'i &= \\begin{cases} \\cfrac{d_i}{b_i} & ; & i=1,2,\\dots,k \\ \\cfrac{d_i-d'{i-k}a_i}{b_i-c'_{i-k}a_i} & ; & i=k+1,k+2,\\dots,n. \\ \\end{cases} \\end{align} $$\nBack substitution:\n$$ \\begin{align} x_n &= d'n\\ x_i &= d'_i-c'_ix{i+k} & ; {}& i=n-1,n-2,\\dots,1. \\end{align} $$\nI've written a quick implementation in Cython:\ncimport numpy as cnp\n# NB: `b` and `d` are modified in place\ncpdef TDMA_offset(const double[:] a, double[:] b, const double[:] c, double[:] d):\ncdef size_t i, k, m, n\nm = a.shape[0]\nn = b.shape[0]\nk = n - m\n# Forward sweep\nfor i in range(m):\nd[i+k] -= d[i]*a[i]/b[i]\nb[i+k] -= c[i]*a[i]/b[i]\n# Back substitution\nfor i in range(m-1, -1, -1):\nd[i] -= d[i+k]*c[i]/b[i+k]\nfor i in range(n):\nd[i] /= b[i]\nThis approach still doesn't make use of the fact that $M$ is symmetric, and a parallel implementation would also be very nice.\nFollowing the comment by <PERSON>, I made a simple Python test script:\nimport numpy as np\nfrom cymodules import _solvers\nfrom scipy import sparse\ndef test_trisolve(n=10, k=5):\na = np.random.randn(n - k)\nb = np.random.randn(n)\nc = np.random.randn(n - k)\nx = np.random.randn(n)\nM = sparse.diags((a, b, c), (-k, 0, k), format='csc')\nd = M.dot(x)\n# solve for x in place\nx_hat = d.copy()\n_solvers.TDMA_offset(a, b, c, x_hat)\nprint \"||x - x_hat|| = \", np.linalg.norm(x - x_hat)\nI've tested my solver for a variety of values of $n$ and $k$, including cases where $k \\geq (n - 1) / 2$:\ntest_trisolve(n=10, k=3)\n# ||x - x_hat|| = 1.67369803253e-15\ntest_trisolve(n=10, k=6)\n# ||x - x_hat|| = 6.85231143806e-16\nIt seems to be working OK.", "262" ], [ "How can I improve my algorithm for finding optimally balanced P-way partitioning of array\nI have an array of $N$ weights $w_i$, say $w_i={4, 5, 12, 16, 3, 10, 1}$, and I need to divide this array into $P$ partitions such that partitions are optimally balanced, i.e. that maximum sum of weights of any partition is as small as possible. Luckily the problem is constrained by the fact that the weights can't be reordered. If the number of partitions is three, the above example would give the optimal partitions: ${4, 5, 12}, {16}, {3, 10, 1}$.\nI have found efficient recipes (e.g. partition problem, subset sum, https://cs.stackexchange.com/questions/82479/optimal-partition-of-book-chapters, https://cs.stackexchange.com/questions/38330/a-partition-algorithm, https://cs.stackexchange.com/questions/89663/an-algorithm-for-k-way-array-partitioning) for many similar problems for the cases where the weights are unordered sets and/or the number of partitions is fixed at 2 or 3, but none that seem to exactly address my problem where the number of partitions is arbitrary.\nI have solved the problem myself using divide-and-conquer algorithm (written in Python below), but it seems to be awfully slow for many partitions (e.g.", "690" ], [ "N=100, P=8). So I was thinking that there got to be a better way, using dynamic programming or some other clever tricks?\nDoes anyone have any suggestions?\nSlow Python divide-and-conquer algorithm: ``` def findOptimalPartitions(weights, num_partitions): if num_partitions == 1: # If there is only one partition, it must start at the first index # and have a size equal to the sum of all weights. return numpy.array([0], dtype=int), sum(weights)\n# Initially we let all partitions start at zero, meaning that all but the\n# last partition gets zero elements, and the last gets them all.\npartition_offsets = numpy.array([0] * num_partitions)\nmax_partition_size = sum(weights)\n# We now divide the weigths into two partitions that split at index n.\n# We know that each partition should have at least one element, so there\n# is no point in looping over all elements.\nfor n in range(1, len(weights) - num_partitions):\nfirst_partition_size = sum(weights[:n])\nif first_partition_size > max_partition_size:\n# If the first partition size is larger than the best currently\n# found, there is no point in searching further.\nbreak\n# The second partition that starts at n we now further split into\n# subpartitions in a recursive manner.\nsubpartition_offsets, best_subpartition_size = \\\nfindOptimalPartitions(weights[n:], num_partitions - 1)\n# If the maximum size of any of the current partitions is smaller\n# than the current best partitioning, we update the best partitions.\nif ((first_partition_size < max_partition_size)\nand (best_subpartition_size < max_partition_size)):\n# The first partition always start at 0. The others start at\n# ones from the subpartition relative to the current index, so\n# add the current index to those.\npartition_offsets[1:] = n + subpartition_offsets\n# Find the maximum partition size.\nmax_partition_size = max(first_partition_size, best_subpartition_size)\nreturn partition_offsets, max_partition_size\n```\nEDIT: A trivial Greedy algorithm where the last partition will typically be too large. ``` def greedyPartition(weights, num_partitions): target_size = sum(weights) / num_partitions\npartition_offsets = numpy.zeros(num_partitions, dtype=int)\npartition_sizes = numpy.", "864" ], [ "Open Source Quadratic Programming with Piecewise Linear Objective\nI am looking for an open source solver to solve the a quadratic programming problem with an additional piecewise linear objective, as show below. The problem is fairly small ($\\mathbf{x}$ is a vector of dimension 120).\n\\begin{equation} \\max_{x}: \\mathbf{x}^{T} \\mathbf{q_0} - \\mathbf{x^{T}} P_0 \\mathbf{x} - f(\\mathbf{x}) \\end{equation}\nNote that above $P_0$ is positive semidefinite and $f$ is piecewise linear for each variable in $\\mathbf{x}$ but not convex.", "935" ], [ "For each $x_i$, $i \\in \\left{1, ..., 120\\right}$, $f(x)$ would be a vector of coordinate points, e.g.\n[(x_0, y_0), (x_1, y_1), ..., (x_N, y_N)]\nFor any given $x_i$, $f(x_i)$ looks something like the following.\nSince $f$ does not depend on any cross terms in $\\mathbf{x}$, the above optimization could also be written as\n\\begin{equation} \\max_{x}: \\mathbf{x}^{T} \\mathbf{q_0} - \\mathbf{x^{T}} P_0 \\mathbf{x} - (f(x_1) + ... + f(x_{120})) \\end{equation}\nThe are also linear constraints of the form $A\\mathbf{x} < \\mathbf{b}$ are added.\nI have formulated the problem in Gurobi which is fairly straightforward but was hoping to compare this to an open source solver. Looking around it seems like GLPK would work for this, but I have no experience using this library so was hoping for a bit of info related to this or alternative solutions.\nA sample problem for gurobi using the matlab API is shown below.\nN = 2;\nq_0 = [-3.31e3, -5.07e3];\nP_0 = [-0.90e-04 -0.63e-04;\n-0.63e-04 -0.90e-04];\nx = [-2.0000e9, -1.0000e9, -0.8000e9, -0.6000e9, -0.4000e9, -0.2500e9,...\n-0.1000e9, -0.0500e9, -0.0250e9, -0.0100e9, -0.0010e9, 0, 0.0010e9,...\n0.0100e9, 0.0250e9, 0.0500e9, 0.1000e9, 0.2500e9, 0.4000e9,...\n0.6000e9, 0.8000e9, 1.0000e9, 2.0000e9];\ny = [2.938964e6, 0.753364e6, 0.488104e6, 0.280144e6, 0.129472e6,...\n0.053766e6, 0.011007e6, 0.003751e6, 0.001435e6, 0.000465e6,...\n0.000037e6, 0, 0.000037e6, 0.000465e6, 0.001435e6, 0.003751e6,...\n0.011007e6, 0.053766e6, 0.129472e6, 0.280144e6, 0.488104e6,...\n0.753364e6, 2.938964e6];\nparams.outputflag = 0;\n%formulate model\nmodel.obj = zeros(N, 1);\nmodel.Q = sparse(P_0);\nmodel.A = sparse(zeros(1, N));\nmodel.sense = '=';\nmodel.rhs = 0;\nmodel.ub = repmat(1e9, N, 1);\nmodel.lb = repmat(-1e9, N, 1);\nmodel.modelsense = 'max';\n% piecewise tcosts\nfor i = 1:2\nmodel.pwlobj(i).var = i;\nmodel.pwlobj(i).x = x;\nmodel.pwlobj(i).", "935" ], [ "Find dominated or subsumed linear inequalities efficiently\nProblem statement\nGiven a set of $N$ linear inequalities of the form $a_1x_1 + a_2x_2 + ... + a_Mx_M \\geq RHS$, where $a_i$ and $RHS$ are integers. The inequality $A$ dominates or subsumes inequality $B$ if all its coefficients are less or equal and $RHS_A \\geq RHS_B$. Most inequalities are sparse, i.e. most coefficients are zero. Usually, both $N > 1000$ and $M > 1000 $. I'm trying to identify dominating or subsuming inequalities efficiently.\nWhat are quick ways to find a) if an inequality is dominated by any other inequality, and b) which inequalities are dominated by a given inequality?\n(Monte-Carlo algorithms are fine, that only report correct results most of the time)\nProposed solutions in the literature\n<PERSON>, N. and <PERSON>, A., 2005, June. Effective preprocessing in SAT through variable and clause elimination. In International conference on theory and applications of satisfiability testing (pp. 61-75). Springer, Berlin, Heidelberg. (chapter 4.2) discuss a variant of this problem in the context where all coefficients are binary, i.e. $a_i \\in {0, 1}$. They propose occurrence lists, one per variable $x_i$, containing all inequalities with non-zero coefficients $a_i$. Additionally they use a hashing scheme, similar to Bloom filters, to quickly eliminate candidates. I don't see how to translate this to non-binary coefficients.\n<PERSON>, T., <PERSON>, R.E., <PERSON>, Z., <PERSON>, <PERSON> and <PERSON>, D., 2020.", "603" ], [ "Presolve reductions in mixed integer programming. INFORMS Journal on Computing, 32(2), pp.473-506. (chapter 5.2) discuss a variant of the problem, but don't solve it. They first hash inequalities by indices of non-zero coefficients and the coefficient values. Additionally, they limit their search to a small subset of inequalities.\n<PERSON>, S., 2013. Simple and efficient clause subsumption with feature vector indexing. In Automated Reasoning and Mathematics (pp. 45-67). Springer, Berlin, Heidelberg. describes Feature Vectors for clauses and a kd-tree-like data structure to query combinations of feature vectors.\nThings I've tried\n* The trivial solution is to check all pairs of inequalities in $O(n^2)$. Unfortunately, that's too slow for my application where I have millions of inequalities.\n* I tried performing a random projection of the coefficients for every inequality, resulting in a projection $p_j$ for every inequality. An inequality $j$ can only dominate inequality $k$ if $p_j \\leq p_k$. Thus we don't have to check all pairs. I repeat this process 10 times with multiple random projections, and use the random projection where I have to check the fewest pairs. In practice this is not effective, as most coefficients are zero - and it's unlikely that a random projection focusses exactly on the few non-zero elements. It doesn't help nearly enough.\n* Similarly I implemented Feature Vectors, but couldn't replicate the performance reported by <PERSON>.\n* AFAIK, multi-dimensional data structures break down in high-dimensional scenarios (curse of dimensionality). I'm not aware of indexing techniques that work for high-dimensional range queries.\n* I thought about Bloom filters, unsuccessfully.\n* I thought about randomized algorithms, unsuccessfully.\nDo you have any other ideas?", "603" ] ]

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[ [ "what is the geometric interpretation of a general 'state space' in classical mechanics?\nLet $\\pmb{q}\\in\\mathbb{R}^n$ be some n generalized coordinates for the system (say, a double pendulum). Then the 'state space' is often examined using either the 'Lagrangian variables', $(\\pmb{q},\\dot{\\pmb{q}})\\in\\mathbb{R}^{2n}$ (satisfying the Euler-Lagrange equations), or using canonical variables, $(\\pmb{q},\\pmb{p})\\in\\mathbb{R}^{2n}$ (satisfying <PERSON>'s canonical equations). But these are just coordinate representations (in some chart) in $\\mathbb{R}^{2n}$; the former set, $(\\pmb{q},\\dot{\\pmb{q}})$, are coordinates for a point on the tangent bundle, $\\mathbf{T}\\mathbb{Q}$, and the latter set, $(\\pmb{q},\\pmb{p})$, are coordinates for a point on the cotangent bundle, $\\mathbf{T}^\\mathbb{Q}$ (where $\\mathbb{Q}$ is the n-dimensional configuration manifold). We could use some other coordinate chart, $(\\pmb{q}',\\dot{\\pmb{q}}')$ or $(\\pmb{q}',\\pmb{p}')$, but these would still be coordinates for the same point on either $\\mathbf{T}\\mathbb{Q}$ or $\\mathbf{T}^\\mathbb{Q}$, respectively. Further, in these two types of state space coordinates, the first n coordinates are always 'position level' coordinates, while the last n coordinates are always 'velocity/momenta level' coordinates.\nMy question: We can also transform some other state space coordinates, $\\pmb{z}\\in\\mathbb{R}^{2n}$, where the separation between 'position coordinates' and 'velocity/momenta coordinates' is lost (for example, the classic Keplerian orbital elements for the two body problem $\\pmb{z}=(a,e,i,\\Omega,\\omega,\\nu)\\in\\mathbb{R}^6$).", "101" ], [ "In general, what is the geometric meaning of some general state space coordinates, $\\pmb{z}\\in\\mathbb{R}^{2n}$, which are simply any 2n independent coordinates which fully define the state of the system? This is the coordinate representation of a point on...what?\nI suppose we could say that $\\pmb{z}\\mapsto (\\pmb{q},\\dot{\\pmb{q}})$ is just a coordinate transformation (transition function) for a point $(\\text{x},\\mathbf{v})\\in\\mathbf{T}_{\\text{x}}\\mathbb{Q}$ in which case $\\pmb{z}$ is just some alternative coordinate chart for $\\mathbf{T}\\mathbb{Q}$. But we could also come up with a coordinate transformation $\\pmb{z}\\mapsto (\\pmb{q},\\pmb{p})$ for some point $(\\text{x},\\mathbf{p})\\in\\mathbf{T}^_{\\text{x}}\\mathbb{Q}$ in which case $\\pmb{z}$ would be some coordinate chart for $\\mathbf{T}^\\mathbb{Q}$. But $\\mathbf{T}^*\\mathbb{Q}\\neq \\mathbf{T}\\mathbb{Q}$.\nExample: The classic two-body problem. We could use 'lagrangian coordinates', $(\\pmb{q},\\dot{\\pmb{q}})=(r,\\phi,\\theta,\\dot{r},\\dot{\\phi},\\dot{\\theta})$, or canonical coordinates $(\\pmb{q},\\pmb{p})=(r,\\phi,\\theta,p_r,p_\\phi , p_\\theta )$, which are coordinates (in the spherical coordinate chart) for $\\mathbf{T}\\mathbb{Q}$ and $\\mathbf{T}^\\mathbb{Q}$, respectively. We could transform to their cartesian counterparts but they are just different coordinates for the same points.", "101" ], [ "Are differentials of a smooth maps tensors? Connection to Jacobian matrices?\nI'm trying to learn about smooth manifolds and differential geometry in order to learn the geometric view of classical mechanics. I'm confused about what kind of \"object\" the differential of a smooth map is.\nSet up: Let $M$ be some smooth n-dimensional manifold and let $f: M \\to M $ be a smooth map from $M$ onto itself such that a point ${x}\\in M$ is mapped to ${y}=f({x})\\in M$. Let $(x^1,\\dots ,x^n)\\in \\mathbb{R}^n$ and $(y^1,\\dots ,y^n)\\in \\mathbb{R}^n$ be the coordinate representations of the points ${x}$ and ${y}=f({x})$ in some smooth chart.", "916" ], [ "The differential of $f$ (evaluated at ${x}$) is then a linear map between tangent spaces, $\\mathbf{d} f_x: T_x M \\to T_{f(x)} M \\equiv T_y M$.\nmy question: Is it correct to say that the matrix representation of $\\mathbf{d} f_x$ is given by the Jacobian $\\tfrac{\\partial y^i}{\\partial x^j}$? If so, is $\\mathbf{d} f$ a (1,1)-tensor field and $\\tfrac{\\partial y^i}{\\partial x^j}$ are the components of $\\mathbf{d} f_x \\in T_y M \\otimes T^*_x M$? Can we then write it using coordinate basis vector fields $\\mathbf{e}_i$, and 1-forms $\\boldsymbol{\\epsilon}^i$ as:\n$$ \\mathbf{d} f _x \\;=\\; \\frac{\\partial y^i}{\\partial x^j} \\mathbf{e}_i|_y \\otimes \\boldsymbol{\\epsilon}^j|_x \\;=\\; \\frac{\\partial y^i}{\\partial x^j} \\frac{\\partial}{\\partial y^i} \\otimes \\mathbf{d} x^j \\quad \\in T_y M \\otimes T^*_x M \\qquad (1) $$\nThe above is indeed a linear map $T_x M \\to T_{f(x)}M$. But $\\frac{\\partial y^i}{\\partial x^j} \\frac{\\partial}{\\partial y^i} = \\frac{\\partial}{\\partial x^j}=\\mathbf{e}_j|_x$ so, if the above is correct (is it?), then it is the same thing as\n$$ \\mathbf{d} f _x \\;=\\; \\frac{\\partial}{\\partial x^j} \\otimes \\mathbf{d} x^j \\;=\\; (\\mathbf{e}_j\\otimes \\boldsymbol{\\epsilon}^j)|_x \\qquad\\qquad (2) $$\nAnd isn't this just the identity tensor field evaluated at the point $x$? What's going on here? Is it possible to expand the differential, either $\\mathbf{d}f$ or $\\mathbf{d}f_x$, as a linear combination of basis vectors (or rather, tensor products of them)? Or is my attempt to associate $\\mathbf{d} f$ with a tensor misguided?\nAnother question: If $f$ is the map and $y^i$ are just the labels we give to its output, should the jacobian $\\frac{\\partial y^i}{\\partial x^j}$ actually be written as $\\frac{\\partial f^i}{\\partial x^j}$? This is perhaps a small detail with little consequence but I'm just curious. (I'm abusing notation here by using $f$ to denote both the smooth map on $M$ as well as its coordinate representation, $\\varphi\\circ f \\circ \\varphi^{-1}$, on $\\mathbb{R}^n$)\nEdit: question 2: Based on <PERSON> answer, I see why $\\mathbf{d} f$ is not really a tensor field since $\\mathbf{d} f_x$ maps between tangent spaces of two different points.", "281" ], [ "I think there is some sort of bug near the end of the first answer (joshphysics), possibly in the variational step which involves integration by parts. Unless some further assumptions were used. Otherwise the implied conclusion seems to be that the EL eqns for any functional with integrand $F(x(s),\\dot{x}(s))$ are generally the same as for the functional with integrand $F^2$.\n[A simple counterexample is $F = x(s)$, though I realise this is getting away from geodesics.", "359" ], [ "Then the EL eqn for $F^2$ would be $x=0$ whereas the EL eqn for $F$ itself would be $1=0$.]\nAnyway, getting back to the original question, often the words \"Cauchy-Schwarz\" appear when relating $\\int f^2$ to $\\int f$.\nIgnoring that, and looking just at EL equations, consider minimizing/maximizing the two functionals $\\int F^2 ds$ and $\\int F ds$ (with the same parameter and bcs), where $F = F(x(s),\\dot{x}(s))$. When are these two problems equivalent (or at least, one implies the other)?\nThe EL eqns for the two cases are generally different (cf counterexample above), but one condition for equivalence is $dF/ds = 0$ (when evaluated on a solution to either of the two EL eqns).\nWe also have the Beltrami identities for each case, which are first integrals of the EL eqns (cf energy conservation): for $F$ we have $\\dot{x}_i\\frac{\\partial F}{\\partial \\dot{x}_i} - F = c_1$ and for $F^2$ we have $\\dot{x}_i\\frac{\\partial (F^2)}{\\partial \\dot{x}_i} - F^2 = c_2$ (*).\nRestricting to the problem of geodesics on some surface, we have an integrand of the form $F = \\sqrt{g_{ij}(x)\\dot{x}^i\\dot{x}^j}$ and this satisfies $\\dot{x}_i \\frac{\\partial F}{\\partial \\dot{x}_i} = F$ (identically), and also satisfies $\\dot{x}_i \\frac{\\partial (F^2)}{\\partial \\dot{x}_i} = 2F^2$ (+).\nLet's suppose we have a solution to the EL eqn for $F^2$, and thus to the Beltrami identity $()$ for $F^2$. Then () and (+) together give $F^2 = c_2$ i.e. $F$ is constant when evaluated on our solution.\n[this is essentially point 9 of <PERSON>'s answer] Hence the equivalence condition mentioned above ($dF/ds = 0$) is satisfied, and so the EL eqn for $F$ is also satisfied.\nThe converse doesn't hold in general since the <PERSON> identity for such an $F$ is satisfied identically (with $c_1 = 0$), so does not give anything \"extra\".", "374" ], [ "Edit: As the comments seem to misinterpret my question, let me clarify it. I don't even understand what is the meaning of multiplying a vector (state) by a number with units such has $\\hbar$. By definition, in a vector space you can multiply by a vector by a scalar from the field of definition ($\\mathbb C$ in our case), but I can't make sense of multiplying by a number with units.\nI will build on the material in <PERSON>'s answer and my answer to 'Is 0m dimensionless? .\nIn physics, calculations are normally done with physical quantities, and not with real numbers. This is important, because physical quantities are not a field, since not all additions are well-defined.", "359" ], [ "Instead, the set of physical quantities is a set $$ \\mathcal P = {(q,d):q\\in \\mathbb C,d\\in \\mathbb Q^N} $$ whose elements consist of the quantity value $q$, which may be real but we allow in general to be complex, and the dimension, which is an $N$-tuple of rational numbers, with $N$ the number of algebraically-independent dimensions that you want to include in your theory.\nNow, as I said, $\\mathcal P$ is not a field, and instead it what you might call a field-with-dimensions, which is equipped with the following operations:\n* addition, $(q_1,d)+(q_2,d) = (q_1+q_2,d)$, when both quantities have equal dimension; and\n* multiplication, $(q_1,d_1)\\times(q_2,d_2) = (q_1\\times q_2, d_1+d_2)$.\nSince these are not field operations, the field axioms do not even make sense. However, they have transparent generalizations; if you really care about this then it's a good exercise to write them down.\nNow, this works thus far for scalar physics, but we have yet to touch vector spaces. Those are normally defined relative to a field, but we want to move away from those dimensionless mathematics, so we need to define a new structure, which you might call a vector-space-with-(physical)-dimensions. To do this we need a pre-existing vector space $V$ over $F=\\mathbb C$ (or $\\mathbb R$ as required), and we basically generate $\\mathbb Q$-fold copies of $V$, each with its own physical dimension: $$ V_\\mathcal P = {(v,d):v\\in V,d\\in \\mathbb Q^N}. $$ As above, we need to define the operations anew, and this is again transparent:\n* addition, $(v_1,d)+(v_2,d) = (v_1+v_2,d)$, when both vectors have equal physical dimension; and\n* scalar multiplication, $(s,d_1)\\times(v,d_2) = (s\\, v, d_1+d_2)$, for $s\\in \\mathbb F$ and $v\\in V$.\nSince these are not the algebraic operations of a vector space, the vector-space axioms no longer make sense, so instead they need to be generalized to this setting; again, the generalization is transparent and obvious.\nFinally, what happens with linear operators? We want to assign them physical dimensionality as well, so how is that done? Basically, again, by direct imposition: we define linear operators on vector-spaces-with-physical-dimensions as functions $$ A:V_\\mathcal P \\to V_\\mathcal P $$ with an assigned dimension $d_A$ such that $A(v,d_v)$ has dimension $(d_V+d_A)$ for every $(v,d_v)\\in V_\\mathcal P$, and such that\n* $A\\big((v_1,d_v)+(v_2,d_v)\\big) = A(v_1,d_v)+A(v_2,d_v)$; and\n* $A((s,d_s)\\times(v,d_v)) = (s,d_s)\\times A(v,d_v)$.\nAt least on the surface, this looks different enough to the normal definition of linear operator that the entire work needs to be repeated, but this is easy to avoid.", "499" ], [ "... my question is why can we use <PERSON>'s rotational second law in $P$'s frame? The point $P$ of contact moves (indeed, accelerates, with time). I suppose that, at an instant of time, we can consider $P$ as the point on the fixed ground which is in contact with the disk.\nWhen in doubt, be careful; assumptions here do not appear as they seem.\nLet $\\textbf{r}{\\text{s}}$ be the vector connecting our lab frame to some other stationary frame of reference, and let all positions in the lab frame $\\textbf{r}_i$ be represented as $\\textbf{r}\\text{s} + \\textbf{δ}i$, where $\\textbf{δ}_i = \\textbf{r}_i - \\textbf{r}\\text{s}$.\nAngular momentum of a body, in that other frame of reference, is defined by $$\\textbf{L} = \\int_{\\,V}\\textbf{δ}{dm} \\times (\\dot{\\textbf{δ}}{dm}\\, dm) = \\int_{\\,V}(\\textbf{r}{dm} - \\textbf{r}\\text{s})\\times\\dot{\\textbf{r}}_{dm}\\,dm$$\nWith that in mind, let's examine the validity of switching stationary frames.", "101" ], [ "For constant different $\\textbf{r}_\\text{s}$, it might be of value to find the geometric shape such that $\\textbf{L}$ remains invariant.\nThen the angular momentum, for different $\\textbf{r}\\text{s}$, becomes $$\\begin{align} \\textbf{L} &= \\int{\\,V}(\\textbf{r}{dm}\\times\\dot{\\textbf{r}}{dm})\\,dm - \\int_{\\,V}(\\textbf{r}\\text{s}\\times\\dot{\\textbf{r}}{dm})\\,dm \\ &= \\int_{\\,V}(\\textbf{r}{dm}\\times\\dot{\\textbf{r}}{dm})\\,dm - \\textbf{r}\\text{s}\\times\\left(\\int{\\,V}dm\\right)\\left(\\frac{\\int_{\\,V}\\dot{\\textbf{r}}{dm}\\,dm}{\\int{\\,V}dm}\\right) \\ &= \\int_{\\,V}(\\textbf{r}{dm}\\times\\dot{\\textbf{r}}{dm})\\,dm - \\textbf{r}\\text{s}\\times M\\dot{\\textbf{r}}\\text{CM} \\ \\end{align}$$\nDue to the cross product, the endpoints of $\\textbf{r}\\text{s}$ that correspond to the same $\\textbf{L}\\,$ effectively draws a line parallel to whichever direction $\\dot{\\textbf{r}}\\text{CM}$ points in.\nHence, if we were to consider a disk rolling down a slope, we can set the endpoints of $\\textbf{r}\\text{s}$ to sit on the contact points the disk rolls through, since this is a straight line. As the disk rolls by each endpoint, we can peer in each stationary frame and safely analyze the torques and forces as expected, in a snapshot of time; the contributions $\\dot{\\textbf{L}}=\\textbf{Γ}$ considered correspond to a commensurate change in the same angular momentum across our stationary $\\textbf{r}\\text{s}$ vectors.\n$$\\rule[0]{300pt}{0.4pt}$$\nIt's important to note that if the endpoint of $\\textbf{r}s$ is legitimately translating along with the contact point of the disk, then the angular momentum obtained is different from the angular momentum we analyzed through jumping across stationary frames—we must take into account $\\dot{\\textbf{r}}\\text{s} \\neq 0$, and the equivalence between $\\dot{\\textbf{L}}$ and $\\textbf{Γ}$ is not quite true.\n... the result holds only in an inertial frame precisely because <PERSON>'s second law has been invoked (with the standard \"coincidence\"/exception of the result holding in the CM frame being noted).", "804" ], [ "Are the linear Lie groups matrices, tensors, or both?\nIn some ways, this is a question about notation.\nIn my experience, I have only seen the classical Lie groups — such as $GL(n,\\mathbb{R})$, $SL(n,\\mathbb{R})$, $O(n,\\mathbb{R})$, $SO(n,\\mathbb{R})$, $Sp(2n,\\mathbb{R})$, etc. — introduced and defined in terms of (real) matrices (I'm sticking with $\\mathbb{R}$ as the field just to keep things simpler).\nMy question: can a 2nd order tensor be a member of one of these groups? Or is it only the matrix representation of a tensor that can be a member of one of these groups? If the answer is the latter, then are there corresponding tensor groups for tensors whose matrix representation (in any basis) is a member of one of the classic <PERSON> groups?\nExample: The general linear group, $GL(n,\\mathbb{R})$, is defined for matrices simply as the group of all non-singular real square matrices: $$ GL(n,\\mathbb{R}) \\;=\\; { A\\in M_{n,n}(\\mathbb{R}) \\;|\\; \\text{det}(A)\\neq 0 } $$\nwhere $M_{n,n}(\\mathbb{R})$ denotes $n\\times n$ real matrices. Now, consider some finite n-dimensional (real) vector space, $V$, with an inner product.", "364" ], [ "If we have some (1,1)-tensor $\\mathbf{Q}\\in \\mathcal{T}^1_1(V)$ with non-zero determinant (i.e., $\\mathbf{Q}$ is non-degenerate), then can we say that $\\mathbf{Q}\\in GL(n,\\mathbb{R})$? Or maybe the proper notation would be $\\mathbf{Q}\\in GL(V)$?\nAlthough I used a (1,1)-tensor for this example, I don't think anything would change if $\\mathbf{Q}$ were a (2,0)-tensor or a (0,2)-tensor, would it? (I am assuming we have an inner product and can thus raise and lower indices as we please)\nDoes anything change for the other classical Lie groups? For instance, if $[Q]$ is the matrix representation (in any basis) of $\\mathbf{Q}$ and satisfies $[Q][Q]^{\\top}=I$ such that $[Q]\\in SO(n,\\mathbb{R})$, can we say $\\mathbf{Q}\\in SO(n,\\mathbb{R})$? Or perhaps $\\mathbf{Q}\\in SO(V)$? (this would mean that $\\mathbf{Q}\\cdot\\mathbf{Q}^{\\top}=\\delta^i_j\\mathbf{e}_i\\otimes\\boldsymbol{\\epsilon}^j=\\mathbf{I}$, where, here, the dot denotes a contraction using the inner product/metric, $\\mathbf{e}_i$ and $\\boldsymbol{\\epsilon}^i$ are basis vectors and basis 1-forms for $V$ and $V^*$, and $\\mathbf{I}$ is the identity tensor for $V$. )\nAnother question: same question for the associated Lie algebras. I.e., can a tensor be a member of $\\mathfrak{so}(n,\\mathbb{R})$ or only a matrix?\nEdit: To clarify, I'm using the term tensor such that $T\\in \\mathcal{T}^p_q(V)$ means $T$ is (p+q)-linear map, $T:(V^)^{\\times p} \\times V^{\\times q} \\to \\mathbb{R}$. That is, $T= V^{\\otimes p}\\otimes (V^)^{\\otimes q}$.", "656" ], [ "It seems the confusion is coming from thinking that in the body $\\mathbf{V}$ equals $\\dot{\\mathbf{Q}}$. This is however not true. The position vector $\\mathbf{Q}$ of a point that rotates with the body is constant. (Arnol'd allows more general motions where a point $\\mathbf{Q}$ moves in a rotating coordinate system $\\mathbf{K}\\,$ but let's stick to the case of constant $\\mathbf{Q}\\,.$)\nIt is true that in space $\\mathbf{v}=\\dot{\\mathbf{q}}=[\\omega,\\mathbf{q}]$ holds, and in the body $$ \\mathbf{V}=[\\Omega,\\mathbf{Q}]\\,.", "499" ], [ "$$ (This is Arnol'd's notation for the cross product). But it is not true that the \"velocity in the body\" $\\mathbf{V}$ equals $\\dot{\\mathbf{Q}}$ (the derivative of a constant is zero).\nWhen $B$ is the time dependent rotation matrix around the $z$-axis,\n\\begin{eqnarray}\\label{eZRot} B=\\left(\\begin{array}{ccc}\\cos(\\alpha\\,t) & -\\sin(\\alpha\\,t) & 0 \\ \\sin(\\alpha\\,t) & \\cos(\\alpha\\,t) & 0\\ 0 & 0 & 1 \\end{array}\\right)\\,, \\end{eqnarray} and $\\mathbf{Q}$ is, say, the vector $$ \\mathbf{Q}=\\left(\\begin{array}{c}1\\0\\0\\end{array}\\right) $$ then $$ \\mathbf{q}=\\left(\\begin{array}{c}\\cos(\\alpha\\,t)\\\\sin(\\alpha\\,t)\\0\\end{array}\\right)\\,,~~ \\mathbf{v}=\\dot{\\mathbf{q}}=\\alpha\\left(\\begin{array}{c}-\\sin(\\alpha\\,t)\\\\cos(\\alpha\\,t)\\0\\end{array}\\right)\\,,~~ \\mathbf{V}=B^\\top\\mathbf{v}=\\left(\\begin{array}{c}0\\\\alpha\\0\\end{array}\\right)\\,, $$ and $$ \\omega=\\Omega=\\left(\\begin{array}{c}0\\ 0\\ \\alpha\\end{array}\\right)\\,. $$ The equations $\\mathbf{V}=[\\Omega,\\mathbf{Q}]$ and $\\mathbf{v}=[\\omega,\\mathbf{q}]$ are easily verified.\nDenote by $\\mathbf{e}_x,\\mathbf{e}_y,\\mathbf{e}_z$ the cartesian basis vectors fixed in space and by $\\mathbf{E}_x,\\mathbf{E}_y,\\mathbf{E}_z$ their counterparts that are fixed in (i.e. rotating with) the body. Then clearly, $\\mathbf{q},\\mathbf{v},\\omega$ is a system of orthogonal vectors that rotates in space around the axis $\\omega=\\alpha\\mathbf{e}_z$, and, $$ \\mathbf{Q}=\\mathbf{E}_x,\\quad\\mathbf{V}=\\alpha\\mathbf{E}_y,\\quad\\Omega=\\alpha \\mathbf{E}_z $$ is a system of orthogonal vectors that is fixed in the body.", "804" ], [ "I would agree with <PERSON>'s suggestion that the most \"fundamental\" definition of momentum is the quantity that is conserved when the Lagrangian is invariant under spatial translations $\\boldsymbol{x}\\rightarrow\\boldsymbol{x}+\\boldsymbol{s}$.\nHowever, do terms like Lagrangian even make sense when we try to include massless objects?\nYes, absolutely. In fact the machinery used to describe such particles, quantum field theory, is expressed in terms of Lagrangians.\nLagrangian mechanics and generalized momentum\nLet's start with the simpler classical dynamics notion of momentum. We start with a Lagrangian, expressed in terms of the generalized coordinates $q_i$ and their time derivatives, $$L(q_i, \\dot{q}_i)=T(\\dot{q}_i)-V(q_i)$$ where $T$ and $V$ are the kinetic and the potential energies, respectively. The reason we care about the Lagrangian is that it allows us to easily derive the equations of motion for the system under consideration using the Euler-Lagrange equations, $$\\frac{\\partial L}{\\partial q_i}-\\frac{d}{dt}\\left(\\frac{\\partial L}{\\partial\\dot{q}_i}\\right)=0$$ which are a direct result of the principle of least action. There is a famous and beautiful theorem in mechanics by <PERSON>, which states that for every continuous symmetry of the Lagrangian there exists some quantity that stays the same throughout time. More precisely, for some continuous transformation parameterised by $s$, $q_i(t)\\rightarrow Q_i(s,t)$, if $$\\frac{\\partial}{\\partial s}L(Q_i(s,t),\\dot{Q}_i(s,t),t)=0$$ then the quantity $$\\sum_i\\frac{\\partial L}{\\partial\\dot{q}_i}\\frac{\\partial Q_i}{\\partial s}$$ is conserved though all time.", "101" ], [ "These $\\partial L/\\partial\\dot{q}_i$ are known as generalized momenta.\nDefining momentum\nConsider the specific case of a collection of free particles, which has a Lagrangian $$L=\\frac{1}{2}\\sum_i m_i\\dot{\\boldsymbol{x}}_i^2-V(|\\boldsymbol{x}_i-\\boldsymbol{x}_j|)$$ Now consider making a translation $\\boldsymbol{x}_i\\rightarrow\\boldsymbol{x}_i+s\\mathbf{n}$ where $\\mathbf{n}$ is an arbitrary vector. The above Lagrangian is clearly invariant under such a transformation. Therefore we know per <PERSON>'s theorem that the quantity $$\\sum_i\\frac{\\partial L}{\\partial\\dot{\\boldsymbol{x}}_i}\\frac{\\partial(s\\mathbf{n})}{\\partial s}=\\sum_i m_i\\dot{\\boldsymbol{x}}_i\\cdot\\mathbf{n}$$ is conserved. But this is just our usual conservation of the total momentum $\\sum\\boldsymbol{p}_i=\\sum m_i\\dot{\\boldsymbol{x}}_i$ along the direction of $\\mathbf{n}$! So we see that the quantity momentum naturally arises as the thing that is conserved under space-translation symmetry.\nBut this notion of momentum extends much further than free particles. It can be applied to any Lagrangian with space-translation symmetry, with the conserved quantities that arise being given the label momentum.\nSo now, how do massless particles like photons fit into this? For describing particles such as photons we use quantum field theory, however it suffices here to stick to the classical theory.\nLagrangian of fields\nLike the name suggests, in field theory our dynamical variables are fields which are themselves functions of space and time (or, spacetime). As such we replace the usual Lagrangian with a Lagrangian density, $\\mathcal{L}$ which is defined by $$L=\\int\\mathrm{d}^3\\boldsymbol{x}\\,\\mathcal{L}(\\phi(x),\\partial_\\mu\\phi(x),t)$$ where $\\phi(x)$ is the field as a function of spacetime coordinate $x=(t,\\boldsymbol{x})$ and $\\partial_\\mu=\\partial/\\partial x^\\mu=(\\partial/\\partial t,\\nabla)$ is the four-gradient.", "101" ] ]

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[ [ "Past Lives\nFull disclosure: the first time I saw the trailer for ‘Past Lives’ in the theater, I began sobbing uncontrollably. Soundtracked by <PERSON> gorgeous cover of <PERSON>’s “Stay,” I was instantly transfixed by the song’s lyrics combined with the film’s sumptuous visuals.\nNot really sure how to feel about it\nSomething in the way you move\nMakes me feel like I can’t live without you\nWhile the song does not appear in the actual movie, “Stay” perfectly accompanies ‘Past Lives,’ the first feature film from Korean-Canadian playwright and director <PERSON>. It’s a story so intensely personal and lived-in, that it doesn’t seem possible that it is her first movie.\nIt tells the story of <PERSON> (<PERSON>) and <PERSON> (<PERSON>) – two childhood friends from South Korea who fell out of touch when <PERSON>’s family immigrated to Canada. We follow as they reconnect at different points in their adult lives.\nWe’re all impacted differently by our memories.\nIn <PERSON> case, the way that he remembers <PERSON> from when they were young has never left him. When they first are in contact again in their twenties, they are in very different places. <PERSON> is in New York trying to find success as a writer while <PERSON> is finishing up his engineering studies in Korea. They begin talking to each other again over Skype, but <PERSON> struggles with the intense feelings their conversations stir up inside her knowing that they are literally worlds apart.\nBy the time they cross paths again in their thirties, life is even more different between them. <PERSON> is married to a fellow writer named <PERSON> (<PERSON>) and <PERSON> visit to New York City marks a potentially significant conflict for her relationship.\nBased on how I reacted to the trailer initially, I was prepared to cry through this entire movie.", "80" ], [ "And then I was somewhat surprised when that didn’t happen. I was fully invested in the story as it went along, but it was less emotional than I expected.\nUntil, that is, the final 20 minutes of the film.\nThere is a quiet brilliance in <PERSON>’s storytelling and the casting only enhances it. Both leads are remarkable, but <PERSON> is a revelation. He somehow expresses the desperation of longing and all the conflict of a lost love with a simple glance. His posture and anxious body language tell his story in ways the dialogue can only hint at. These final moments brought the tears, big time.\nTo accent the stellar performances and sharp technical aspects, ‘Past Lives’ is scored by <PERSON> and <PERSON> of Grizzly Bear. <PERSON> and <PERSON> also contribute an beautiful original tune called “Quiet Eyes” that plays over the end credits and is a fine soundtrack to finish crying to!\nYes, the pacing of ‘Past Lives’ is languid. I anticipate that those who don’t like the film will argue that it’s just too slow. But if you give in to its charming honesty, it’s hard to resist.\nSimply put, <PERSON> has crafted one of the finest debut films in recent memory.", "529" ], [ "The Menu\n2022 Films Ranked\nA captivating and highly original critique on “The Elite” 1% and their presence within modern society.\nThe Menu is a really well executed dark comedy with elements of horror. It’s a somewhat satirical dissection on pretentiousness and what it means to truly be an “artist.” This film was super entertaining from start to finish and though it was slightly predictable the storyline was one that felt very fresh and original.\n<PERSON> leads this talented ensemble with a heartfelt but unnerving performance that is truly incredible. He, to a certain extent, carries this film through his acting, and helps to make even the slow parts enjoyable and memorable.\nThe food is stunning. Truly some of the most beautiful dishes I’ve ever seen presented on screen.", "241" ], [ "Whether it’s a miniature edible ocean ecosystem or a simple cheeseburger, the food was gorgeous.\nPersonally, I didn’t love the ending. It was fine, but for some reason it just didn’t hit me as hard as I think it should have. It honestly just felt like a mediocre recreation of Midsommar that lacked the shock value and artistic flare.\nIt’s a solid film that has a great message. It’s also executed well and is really entertaining. It’s not a perfect movie by any means and it doesn’t really try anything new from a filmmaking perspective, but if you are into dark comedies or have a passion for the culinary arts, you’ll definitely enjoy this one.\nGrade: 74%", "596" ], [ "Scenes from a Marriage\n“Happiness is contentment.”\nI don’t know if a film has ever broke me the way <PERSON> Scenes from a Marriage crushed me. There’s this profound intimacy that almost makes watching the film feel wrong.\nThere has never been an actor like <PERSON>, she is truly such a chameleon. Her raw vigor and emotion truly drained me. There’s this haunting hopelessness; this feeling that a grip is being let loose.", "1009" ], [ "This brutal honestly shines in both performances. As wonderful as <PERSON> is, <PERSON> is just as incredible.\nThere’s this moment in Episode Four that is so charming on the surface but the underlying weight hits like a freight train. This film is so beautifully haunting and depressing, there’s this obvious love that’s under the surface but the weight and pressure is so crushing.\nWould Recommend!\n“You were awfully attractive as a socialist.”\nNote:\nRe-posting this 2019 review unedited because I logged the wrong cut. Didn’t know the TV cut had its own entry!", "1009" ], [ "May December\nMay December explores the deepest, most unspoken layers in each of its characters. Pitting the stories they tell themselves about who they are against an elusive truth, observing how they break down when confronted with just the suggestion of a reality that breaks their narrative.\n<PERSON> really delivers with something so unexpected, walking a tightrope in executing a distinct tone for this deeply uncomfortable story. It's darkly comic and tragic, but also cerebral in its approach. Very good stuff.", "352" ], [ "<PERSON> has made a beautiful, terrible nesting doll of a film with a uniquely twisted core. Beneath the droll portrait of an actor's obsession with her muse is an unsettling tale of what happens when people refuse to tell the truth.\n<PERSON> and <PERSON> are sensational, but <PERSON> managed to stand out from the two actresses with a sincere standout performance in a tricky role. <PERSON> steals the show in a vulnerable, heartbreaking fashion. Three of the greatest performances of the year.", "529" ], [ "People Having Fun\nDefinitely <PERSON>’s most ambitious and out-there film. It’s the type of thing that truly makes you wonder where the hell it’s going next, and thankfully not in a way that’s annoying or amateur as each section brings about various vibes and situations both perplexing and strange.\nI haven’t been interested in filmmaking for awhile now, or watching independent films for that matter.", "647" ], [ "But I’m glad I decided to watch this. It’s been quite a long time since I viewed a <PERSON> film, and it was a great to be back in the mind of this wholly unique artist. A DIY king.\nGood job dude.\nYou have until Monday to watch, before it’s taken off YouTube for idk how long!!\nhttps://youtu.be/W1UfBHZhO7k?si=Yphp8reJyS2Yuxvd", "410" ], [ "<PERSON> – Monster: The <PERSON> Story\nI’ve seen a lot of people discuss the ethical shades of grey when it comes to making a show such as this. Whether it’s giving this dude more attention or not contacting the real-life victims or whatever else is being said.\nPersonally, I’m not interested in these debates. The morality of cinema has always been a topic I’ve intentionally steered away from, because who am I to say what is and isn’t “right”.\nMy top priority is always story. And as far as this one goes, I was far more impressed than I thought I would be.", "647" ], [ "However, I do think it starts to lose itself a bit once the focus moves away from <PERSON>/his father and emphasizes too much on the impact of the victims. I imagine this was intended to pay tribute to the real-life people, but nonetheless it resulted in a serious drag in the overall narrative.\nIn my opinion, the show hits the hardest when it remains fixated on <PERSON>’s spiral into madness and the ever-increasing evolution of his relationship with his father. Once that moves from the spotlight, it becomes a bit monotonous.\nBut overall, this was an extraordinarily fascinating show, packed with phenomenal performances all around (my favorite of which probably being <PERSON>). It’s a solid recommendation from me.", "282" ], [ "The Beekeeper\n“To bee or not to bee?”\nThe Beekeeper is a 2024 American action thriller film directed by <PERSON> which follows one man's brutal campaign for vengeance which takes on national stakes after he is revealed to be a former operative of a powerful and clandestine organization known as \"Beekeepers\".\nEveryone knows I love a good, cheesy horror film and so the trailer for The Beekeeper was pretty much catnip for me. From its self-serious tone to the one liners, I knew I’d at least have fun with this.\nUnsurprisingly, The Beekeeper is a delight — a capital B B-Movie (or should I say Bee Movie) with its tongue firmly in cheek. Though it’s revenge trappings may recall <PERSON>, I felt it had even more in common with an early 90s <PERSON> flick, particularly Hard to Kill.\n<PERSON> is essentially the fuckin’ Terminator here and though his lack of taking a punch bugged me at first, once he finally takes some hits from a henchman with the funniest accent I’ve ever heard, it’s great.", "995" ], [ "<PERSON> also attempts an American accent but even the film knows it’s bad so comes up with an excuse for it.\nThe villains are also just comically inept, and the committed performances by <PERSON> and <PERSON> are campy as hell — shoutout to the dudes playing the scammers too, they were hilarious.\nOn the whole, The Beekeeper is a fun actioner which well-deserves the buzz. Take your hive (or honey) and see it on the big screen and bee-lieve the hype. I’m so sorry.", "585" ], [ "<PERSON>\nI have been on a string of terrible movies lately, so I was desperate for one to break the streak and luckily, <PERSON> did just that. I had no idea this was coming, but anytime there’s a new soder film, I’m hyped. <PERSON>’s directing was both slick and vexing, making the audience feel like there’s always something more sinister lurking beneath the surface (or behind the screen) hehe. The entire movie caught me off guard, but what really got me was the humor.", "577" ], [ "I don’t know what I was expecting, but that really had me chuckling. Early on, I wasn’t really gelling with <PERSON>’s script, but by the end, I was fully on board, and <PERSON> was clearly having fun with his foreshadowy visuals. So many cool shots and scenes but that chase scene stood high above the rest. Highly recommend; a nice little treat from one of the best living directors.", "657" ] ]

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[ [ "Glow`rious Cheesecake\nIntroduction: Glow`rious Cheesecake\nIf you are looking for a super cool theme party I would suggest.. a Blue light party! There are lots of cool things that you can do with a blue light and one of them is naturally making food glow!\nThere are some ingredients that are naturally glowing under blue light and one of them is Tonic Water. Tonic Water has quinine, which is the natural element that glows in the dark. Therefore that is when the idea of a glow in the dark Gin and Tonic Cheesecake came! Just image a table filled with Gin-tonic`s and a big cheesecake all lighten up!\nSupplies\nFor the base:\n* 100 gr digestive biscuits\n* 50 gr unsalted butter, melted\n* 2 tsp sugar\nFor the Cheesecake:\n* 250 millilitres double cream\n* 1 sachets of powdered gelatine (13 gr x sachet)\n* 300 gr of cream cheese\n* 1 lemon zest\n* 25 ml of gin\n* 60 gr of icing sugar\nFor the gelatine:\n* 500 ml tonic water\n* 150 grams caster sugar\n* 1 sachets of powdered gelatine\nStep 1: Prepare the Biscuit\nGrind the biscuits into a crumbs. Add the melted butter, the sugar and mix (This step can be done by either using a mixer or by hand).\nCover a cake tin with baking paper. Using a spoon press the biscuits crumbs down in the cake tin until well compacted.\nPlace the tin in the fridge for 1h\nStep 2: Prepare the Gelatine for the Cheesecake\nPour 4 tsp of double cream into a pan and heat it up on the stove (it does NOT have to boil). In the meantime, add 1 sachet of gelatine to 4 tsp of cold water by spreading evenly the gelatine powder. Do not mix.\nWhen the double cream is warm, add the gelatine and water (it should be now compacted) to the pan, and stir until the gelatine is completely dissolved.\nLeave it on one side to cool down.\nStep 3: Cheese of the Cheesecake\nBy using a wooden spoon, stir the cream cheese until soft.", "305" ], [ "Add the sieved icing sugar, the lemon zest and the gin, and stir until the ingredients are all well mixed together.\nStep 4: The Cream for the Cheese\nAdd the now cold double cream to the double cream that was left and whip it until it forms stiff peaks.\nAdd, one tsp at a time, the whipped cream to the cream cheese, and stir with the wooden spoon.\nOnce all the cheese is well mixed, add the mixture on top of the biscuit that was prepared on step 1.\nEnsure that the cream is well spread out and even at the top.\nPlace the cheesecake in the fridge for 4h or overnight.\nStep 5: The Magic Ingredient\nGelatine preparation:\nAdd the Tonic Water to a pan a squeeze a lemon in it. Heat the tonic water on the stove. Do NOT let it boil.\nOnce warm enough add the powder gelatine, mix well, and let it rest up until completely cool down.\nStep 6: Decoration\nThis step is completely up to you!\nI added lemon and lime slices but you are free not to do so.\nAdd the cool gelatine on top of the cheesecake (1tsp at a time!). Depending on how big you like the gelatine layer the procedure is different. I would suggest to have a layer of gelatine not higher than 1 cm this is because gelatine tends to break once you open the tin. In that case, before adding the gelatine, using a brush, spread some olive oil on the tin walls. If you are a massive fun of tonic water, and you like a big layer of gelatine, use an acetate sheet to avoid the gelatine getting stacked on the tin.\nPlace the cheesecake in the fridge for at least 4h.\nP.S. If you are not a massive fun of tonic water, you can add lime cordial to the gelatine to give it a sweeter flavour.\nStep 7: Glow Your Cake!\nTurn of your blue light... and make your cake glow!!", "567" ], [ "Galaxy Macarons\nIntroduction: Galaxy Macarons\nThis lovely galaxy-themed macarons are a deliciously and stunning cookie you can make to take your friends to a galaxy far far away! They are also gluten free!!\nSupplies\nIngredients\nMacaron Shell:\n* 200g Sifted Almond meal (You will need more as you will sift out lumps)\n* 200g Pure Icing sugar (again may need slightly more) (It is important to use our icing sugar as using icing mixture can change the texture, this step also makes it gluten-free)\n* 80g Old egg whites, room temp (old egg whites refer to separated egg whites that have been cracked 3-5 days beforehand, covered in a cling wrapped container. this gives a better meringue)\n* 70g Fresh egg whites, room temp (cracked at the time)\n* 50ml water\n* 200g caster sugar\n* Edible food colouring (ideally gel or powdered, not liquid)\nFilling:\n* Use any filling that you like, such as a chocolate-based ganache or salted caramel, I have a separate video for the salted caramel but the ingredients are.\n* 250g caster sugar\n* 70ml water\n* 120ml thickened cream\n* 200g butter\n* 1-2 tsp vanilla bean paste\n* 1-2 tsp salt (I recommend trying this and adding more salt than you think, the shells are quite sweet, therefore having a salty filling complements the flavour really well)\nEquipment:\n* Small saucepans\n* candy thermometer\n* standing mixer with the whisk attachment and metal mixing bowl\n* oven\n* spatula/scraper\n* circle macaron print templates (I use one off of google images with XXXcm diameter circles)\n* Baking paper (NOT wax paper)\n* Piping bags 11mm round piping tip\n* toothpicks or skewers\n* Whisk\nStep 1: Make Your Filling\nI typically make the filling for my macarons the night before I make my macarons so that it can chill adequately.\nI have a separate full video for this on my channel but here are the pictures\nFor the salted caramel filling:\nPlace the 250g caster sugar and 70ml water in a small saucepot and put on high heat until it changes colour. For a sweeter caramel let it go yellow, for a slightly bitter caramel let it go darker (I recommend this as the darker more bitter caramel tastes lovey with the sweet macaron shell).\nOnce it changes colour, immediately whisk in the thickened cream (WARNING) This will steam quickly so be careful not to burn yourself. Then whilst mixing, add a candy thermometer and allow it to come to 108 degrees Celcius (226.4F). Immediately place the pot into cold water to stop the caramel from getting hotter.\nOnce cooled for a minute, add the vanilla bean paste, salt and whisk in half of the butter. (do this quickly so that the butter doesn't melt and separate from the caramel). Then add the rest of the butter and whisk. taste it and make sure it is to your liking.", "305" ], [ "I would make it slightly saltier than expected as the shells are quite sweet.\nYou can fill them with any delicious filling and I have some other options on my channel if you want to try different ones.\nSuch as raspberry and white chocolate ganache, vanilla white chocolate ganache etc.\nStep 2: Prepare Dry Ingredients\nIn a large metal, bowl sift/whisk together the almond meal and pure icing sugar.\nStep 3: Make the Meringue\nPrepare a standing mixer with a whisk attachment and metal mixing bowl. Ensure the bowl is properly clean with no water, dust or oils, it needs to be clean for a good meringue.\nIn a small saucepan heat 200g caster sugar and 50ml water to a boil. With a candy thermometer heat it up to 117.5 Degrees Celcius (243F). Once it reaches this temperature immediately plunge the pot into cold water to stop the sugar syrup from heating up further. Once the syrup stops making small bubbles it is ready to add to the egg whites.\nOn a medium-high speed quickly beat the egg whites for 30 seconds. Then slowly drizzle in the hot sugar syrup so that\n1. The egg whites don't cook\n2. the sugar syrup does not clump and cool on the bowl\nThen continue to beat the meringue on a high speed for about 8-10 minutes, or more until it creates stiff peaks and that the bowl is cool to the touch.\nStep 4:\nIn the metal bowl with the dry ingredients add the 70g new egg whites and mix them all together to form a paste. Then slowly fold in half of the meringue into the mixture.", "136" ], [ "Country Pie\nIntroduction: Country Pie\nThe Country Pie is an egg based pie which can have all the fillings you like! From a meaty one to a veggie one!\nThe saltiness of the filling and the sweetness of the shortcrust merge in an amazing marriage of flavours!\nPrepare it, eat it, enjoy it! And let me know which version you did!\nSupplies\nFor the dough:\n* 200 gr of Flour\n* 75 gr of butter\n* 60 gr of sugar\n* 2 eggs\n* 2 tbsp of milk\nFor the filling:\n* 5 eggs\n* 150 gr of Ricotta cheese\n* 250 gr of mozzarella (or your preferred cheese)\n* 75 gr of Ham\n* 74 gr of Salami\n* Grated parmesan (as you prefer)\n* Black pepper (as you prefer)\nIf you like the veggie option you can substitute the ham and salami with your preferred veggies. Although, bare in mind that you have to cook them first and make sure that all the water has come out. If you are going for this option 10 gr of salt need to be add to the filling!\nIf you decide to go for the mozzarella option, you can either buy a really dry mozzarella or you can open the mozzarella the day before, chop it and leave it open in the fridge to make sure that it dries out. The day after drain the water that has come out.\nStep 1: Prepare the Shortcrust Pastry\nAdd on egg and one yolk to the flour, the sugar and the butter (from the fridge) and mix all together. Knead the dough up until the surface is really smooth.\nStep 2: Leave It Rest\nAdd 2 tbsp of milk, knead the dough. Once the dough absorbed the milk wrap it in cling film and let it rest in the fridge for at least 30 min.\nIf you prefer, you can prepare the dough the night before and leave it to rest for the entire night.\nStep 3: Prepare the Stuffing\nCut the cheese, the ham and the salami.\nIf you like the veggie option cook the veggies and make sure that all the water in excess is taken out. Let them cool.", "277" ], [ "Chop them up.\nStep 4: Prepare the Stuffing Pt2\nMix the 5 eggs with a mixer and when they start to look foamy add a spoon of ricotta at a time and continue to mix. Once the ricotta is finished add the parmesan and the grinded black pepper (how much you like! I like it with a loooot of parmesan and black pepper). Continue to mix for one minute.\nAdd the filling from Step 3 and mix using a spoon. The movement should be slow and from the bottom to the top.\nStep 5: Prepare the Pie\nTake the dough out of the fridge.\nWith the butter, spread a thin layer in the baking tray and pour some flour in and spread it.\nOnce the dough is at room temperature, take 2/3 of the dough and roll it. Place it on the baking tray. Make sure that there are no holes in the dough. Add the filling.\nTake the remaining dough, roll it and cover the pie.\nTake out the dough in excess and using a fork close the pie.\nStep 6: Decorate!\nUsing the left over dough decorate the pie as you prefer! Make sure, with a toothpick to do a small hole on the top, in the middle of the pie (where the flower is in the picture).\nSpread a thin layer of milk on the top of the pie.\nPlace in the oven at 180C for 1 hr.\nIf the pie is burning the edges you can cover it with an aluminium foil layer.\nStep 7: Enjoy!\nTake the pie out of the oven and let it cool down!\nCut it and enjoy!", "702" ], [ "Triple Chocolate Custard\nIntroduction: Triple Chocolate Custard\nThis triple chocolate custard is a delicious and comforting dessert that is so easy to make and tastes incredible!!! why have one type of chocolate custard when you can have all three?? This is a staple in my house and I hope that you try it too.\nSupplies\nIngredients\n* 600ml Full cream milk\n* 6 Egg yolks\n* 100g Caster sugar\n* 50g Cornflour\n* 50g cold unsalted butter (keep it in the fridge until use)\n* 1 Vanilla bean pod (or 1 tsp vanilla bean paste)\n* pinch of salt\n* 70g white chocolate\n* 70g milk chocolate\n* 70g dark chocolate\n* Decorations (strawberries, whipping cream, extra chocolate)\nEquipment\n* Whisk\n* Medium Saucepan\n* Knife\n* Small whisk\n* Microwave\n* Mixing bowls and spoons\n* Serving glasses or bowls\n* Piping bag\nStep 1: Heat Milk\nIn a medium saucepan heat the milk and vanilla bean on medium heat until it lightly simmers. Allow it to cook for a few minutes if there are lumps from the bean sieve them out.\nStep 2: Prepare the Egg Mixture\nIn a mixing bowl whisk together the egg yolks, sugar and cornflour for a few minutes until it becomes light and fluffy.\nStep 3: Mix Together\nOnce both mixtures are ready pour a few tablespoons of warm milk into the egg mixture and whisk together. Ensure you add small amounts of milk so you don't cook the eggs with too much hot liquid. once it is all added place the custard back onto the heat and then continue to whisk for a few minutes until it thickens. this may take about 3-5 minutes.", "604" ], [ "Then take the custard off the heat, allow it to cool for 5 minutes and whisk in the cold butter.\nStep 4: Melt and Add the Chocolate\nMelt each of the white, milk and dark chocolates in the microwave at 30-second intervals, stirring in between. Then divide the custard into 3 separate mixing bowls. Then add one chocolate type to each bowl of custard and mix to combine.\nStep 5: Pipe Into Serving Bowls\nPlace each chocolate custard into a piping bag or ziplock plastic bag. Cut the tips off the bag and then pipe the different custards into the serving bowls. I like the gradient of dark chocolate on the bottom, milk chocolate in the middle and white chocolate on top.\nTo decorate place some whipping cream, a serrated strawberry or grated chocolate, whatever you may want!\nStep 6: Serve!\nServe it straight away as a warm custard or chill in the fridge for a few hours to serve cold.\nI hope that you enjoy these beautiful desserts!!", "136" ], [ "Sandwich Cake\nIntroduction: Sandwich Cake\nWhile preparing food for a birthday party I realized that the best appetisers where the fun ones! Therefore, the idea of having small finger-food sandwiches has been replaced by a sandwich cake! It looks like a cake, you cut it like a cake, but... it`s a sandwich!\nSupplies\n* White sliced bread (16 slices)\n* 400gr of cream cheese\n* 400gr of smoked salmon\n* Lettuce\n* Half cucumber\n* 2 carrots\n* Mayonnaise\n* 3 small avocados\n* 4 salad tomatoes\n* 1 can of tuna\n* 1 Olive\nNon food stuff: baking paper;toothpicks (you can even use spaghetti) and a round base tin (although, this is optional because is mainly used to shape the cake, while, for an easier version, the cake can remain squared shaped).\nYou can fill the sandwiches as you like! Pepperoni, ham, cheese, mozzarella... the more the merrier!\nIt`s a new concept, and people will be surprised!\nStep 1: Prepare the Base\nShape the baking paper as the same size and shape of the chosen base.", "22" ], [ "Cover the baking paper with mayonnaise to ensure that the bread sticks on the paper.\nStep 2: Start the Sandwich\nPlace 4 slices of bread ensure that the straight sides are aligned.\nPrepare the tuna. Drain the can of tuna and place it in a bowl, add 4 spoons of mayonnaise and mix.\nEnsure that the tomatoes, the avocadoes and the salad are sliced and ready to filled the sandwiches.\nStep 3: Build Your Sandwich!\nThis can be done as you like! I personally added:\nbread - a layer of mayonnaise - smoked salmon - salad - avocado - bread - tuna and mayonnaise - tomatoes - bread - mayonnaise - smoked salmon - salad - tomatoes - avocadoes - bread\nStep 4: Cover You Cake\nCut and shape the edges of your cake (make sure that all the external parts of the bread are cut). Once the desired shaped has been achieved cover you cake with cream cheese.\nEnsure that the cream cheese covers all the empty part in between the slices of bread and cover you cake as you are icing a sweet cake!\nStep 5: Decoration And... Enjoy!\nDecorate your cake as preferred.\n(Tu ensure that the flower shaped carrot pieces stayed together I used a spaghetto).\nCut, and eat!", "405" ], [ "Ice-cream Sandwich\nIntroduction: Ice-cream Sandwich\nA sweet bread with coconut flavour and a homemade vanilla ice cream with little pieces of chocolate together to make a great Sweet Sandwich!\nThe tin that I used is a round one, although, I would suggest to use a squared shaped one so when you cut your sandwiches you are not loosing anything!\nGreat for both kids and adults!\nSupplies\nRecipe for 6 sandwiches\nFor the Coconut Bread:\n* 2 big eggs (or 3 small eggs)\n* 75 gr of plain flour\n* 75 gr of coconut flour\n* 8 gr of yeast for sweets (or 4 gr of baking powder with 3 drops of lemon juice)\n* 60 gr of sugar\n* Lemon Zest\n* Butter as needed\nFor the Ice-Cream:\n* 300 mL of double cream\n* 225 gr of condensed milk\n* 20 gr of chocolate\n* Vanilla flavour (either powder or liquid)\nStep 1: Prepare the Sweet Bread\nBeat the eggs with the lemon zest using a hand mixer (you can also use a fork). The eggs are ready when foam is formed. Add the sugar and the yeast and continue to mix.\nAdd the two types of flour (Starting from the coconut flour) spoon by spoon whilst continuing to mix.\nStep 2: Cook and Let It Rest\nWhen all the elements are well mixed prepare a tin. Spread some butter on the tin and place on top a baking paper.", "305" ], [ "Pour the mixture in.\nUsing a squared shaped tin is easier then a round one!\nCook in the oven for 30 minutes at 180 C. If, whilst cooking, you see that the cake is burning, cover the tin with foil and continue to cook.\nStep 3: Cut the Sweet Bread\nLet the bread rest up until is cold.\nCut the bread in two parts.\nStep 4: Prepare the Ice-cream\nStart by pouring the double cream (cold) and whip it. Once ready add the condensed milk and the vanilla and continue to mix.\nAdd the chocolate (cut into small pieces) and mix it in the ice cream using a spoon. Do slow movements because otherwise the whipped cream can loose its form.\nPlace the ice-cream in the freezer for 30 minutes.\nStep 5: Build Your Sandwich\nOnce everything is cooled down add the ice cream in between the two pieces of bread and place it again in the freezer, covered in cling film, for 30 minutes.\nYou can leave the cake there up until you need to cut and eat the sandwiches!\nStep 6: Cut and Enjoy!\nCut the sandwiches and enjoy!!\nKeep the sandwiches in the freezer and let them rest outside the freezer for 5 minutes before eating.", "891" ], [ "Homemade Lemon Curd\nIntroduction: Homemade Lemon Curd\nThis lemon curd is a light and refreshing preserve for toast, scones or desserts. It is best made with fresh lemons straight off the tree if you can get them! I hope you try it as it is super simple to make and absolutely delicious!\nSupplies\nIngredients\n- 2 large eggs (room temperature)\n- 3 large egg yolks (room temperature)\n- ½ cup of 112.5g unsalted butter (room temperature)\n- 1 cup caster sugar\n- Juice and zest of 4 small-medium lemons\n- Pinch of salt\nEquipment\n* Mixing bowl\n* Wooden spoon or whisk\n* Saucepan\n* Knife\n* Fine greater\n* Mixing spoons\n* Storage jar or container\n* *optional sieve\nStep 1: Cream the Butter and Sugar\nFirst, take the room temperature butter and place it into a mixing bowl and cream or smooth out the butter in the bowl with a wooden spoon. Then add the caster sugar and cream them together until it has a sugar scrub consistency.\nThen add one whole egg and mix it into the butter mixture, once fully incorporated add the second egg and mix in until it is light and fluffy. Then mix in the three egg yolks until it is combined.\nStep 2: Prepare the Lemons\nTo prepare your lemons make sure they are room temperature and roll them on your kitchen bench to help loosen the juice inside. Then wash the lemons and then with a fine grater zest the 4 lemons into the butter mixture.\n** it is important to get the yellow part of the zest only, if you grate too much of the rind you will get the bitter white part of the rind.\nThen cut the lemons in half and juice the lemons, ensure you do this in a separate bowl before adding to the butter mixture to capture any lemon seeds.", "491" ], [ "This should yield about 3/4cup of juice.\nThen pour the juice into the butter mixture and add a pinch of salt to balance out the sweetness.\nStep 3: Cook the Curd\nThen add this mixture to a saucepan and place on medium heat and stir continually with a wooden spoon until it thickens, it might take about 5 minutes. Don’t worry if the mixture looks like it is separating just continue to stir, it will come together eventually.\nTo check that it is thick enough take out the wooden spoon and carefully draw a line on the back of the spoon with your finger. If the mixture stays separated it is ready.\nStep 4: Store the Curd\nThis step is optional but you can sieve the lemon curd if you do not want the zest in your curd and want it smoother. I like it with the zest as it gives an even better flavour.\nThen place the lemon curd into a sterilised jar or container and allow it to cool. You can serve it warm or cold after being in the fridge.\nStep 5:\nI hope that you try making this lemon curd it is such a lovely addition to brunch or desserts. It is such a great way to use delicious lemons!", "491" ], [ "Eat-and-Drink Chocolate Chip Cookies\nIntroduction: Eat-and-Drink Chocolate Chip Cookies\nCookies are always better with a nice glass of milk! So... what about using that same cookie to drink that milk? This is how the idea of the drink-and-eat cookie came to life!\nThis recipe is made with white chocolate but you can use every chocolate type you like!\nSupplies\n* 400 gr of plain flour\n* 150 gr of butter\n* 1/2 tsp of salt\n* 100 gr of brown sugar\n* 75 gr of caster sugar\n* 1 egg\n* Vanilla flavouring\n* 180 gr of white chocolate\nStep 1: Prepare the Butter\nBeat the butter (at room temperature) until appears nice and fluffy\nStep 2: Prepare the Cookie Dough\nFirstly, add the brown sugar, the caster sugar and the salt and mix well. Once mixed add the egg and the vanilla flavouring.", "305" ], [ "Mix well.\nAdd the flour and mix using a spatula.\nStep 3: Add Chocolate\nCut 80gr of chocolate and add it to the cookie dough\nStep 4: Shape the \"shot Glasses\"\nOil your hands and prepare small balls with the dough (the size will depend on your silicon mould size) and press the ball against the bottom of the mould creating a small cup.\nAdd the cookies to the oven at 170C for 25 minutes.\nTo make sure that you are not burning your cookies check the oven every 5 minutes.\nStep 5: Melt and Cover With Chocolate\nMelt the remaining chocolate (100gr) and fill the inside of the \"cup\" by covering also the edges. This procedure can be done by using a small teaspoon.\nStep 6: Garnish\nLay some crashed nuts on a plate and press the cup against the garnish (the chocolate MUST be still warm to do this step).\nIf you don`t like nuts you can substitute them with other garnishes (e.g. sparkles, crashed chocolate, etc.)\nLeave the cookie in the fridge for 2 hours (or overnight).\nStep 7: Add Milk and Eat and Drink!\nPour the milk in the cookie and drink it!\nIf you like you can also sparkle some chocolate on top of the milk and use a straw to drink it all!", "122" ] ]

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[ [ "Am I doing this right? Finding the time derivative of expectation value of momentum\nI am currently working through the problems in <PERSON> Intro to Quantum mechanics, with the goal of hopefully understanding how magnets work.\nAt the moment I am a little stuck on one of the early problems in the first chapter. And I would like a Hint about how to proceed.\nThe problem is to solve the time derivative of the expectation value of momentum of a particle. ie: $$ \\frac{d\\left\n}{dt}. $$\nMy working so far\nJust prior to that question the text gives an expression for momentum, $$\\int\\limits_{-\\infty}^{+\\infty}{\\Psi^*\\left[-i\\hbar \\frac{\\partial}{\\partial x}\\right]\\Psi}dx, $$ (Where $\\Psi$ is a function satisfying <PERSON>'s equation, $i$ is the square root of negative 1, and $\\hbar$ is <PERSON>'s constant divided by $2\\pi$.)\nSo my initial approach was to try and differentiate this with respect to $t$. $$ \\frac{d}{dt}\\int\\limits_{-\\infty}^{+\\infty}{\\Psi^*\\left[-i\\hbar \\frac{\\partial}{\\partial x}\\right]\\Psi}dx.", "955" ], [ "$$ However I didn't know how to do that, so I asked around in the maths chatroom, and got a lot of help. Specifically this strategy from @RobJohn: $$ \\begin{align} \\int vv'\\,\\mathrm{d}x &=vv-\\int vv'\\,\\mathrm{d}x\\ &=\\frac12vv+C \\end{align} $$\nSo I suppose it would follow that, $$ \\begin{align} \\int\\limits_{-\\infty}^{+\\infty}{ \\left( \\Psi^ \\left[ \\frac{\\partial}{\\partial x} \\right] \\Psi \\right) }\\,\\mathrm{d}x &= \\left[\\Psi^ \\cdot \\Psi\\right]{-\\infty}^{+\\infty} - \\int\\limits{-\\infty}^{+\\infty} {\\Psi\\frac{\\partial \\Psi^}{\\partial x} }\\,\\mathrm{d}x\\ &= \\frac{1}{2}|\\Psi|^2 \\Big|{-\\infty}^{+\\infty}, \\end{align} $$ And then, $$ \\begin{align} &\\frac{d}{dt}\\int\\limits{-\\infty}^{+\\infty}{\\Psi^\\left[-i\\hbar \\frac{\\partial}{\\partial x}\\right]\\Psi}dx \\&=-i\\hbar \\frac{d}{dt}\\left( \\frac{1}{2}|\\Psi|^2 \\Big|_{-\\infty}^{+\\infty} \\right). \\end{align} $$ But this feels wrong. I'm not sure exactly why. (Maybe it's just because it is the limits of my maths)\nFor reference, regarding what I understand, my maths is pretty low-level, I took a course in undergrad calculus over 10 years ago and only just passed that at the time, and my physics knowledge is not much further than that of an enthusiastic lay person.", "955" ], [ "What is the next step in solving the time derivative of expectation value of the momentum of a particle\nSo this question is a direct follow on from my last question\nI am trying to get an expression for $\\frac{d\\left\n}{dt}$.\nI have my working out below, which was thanks to the Anonymous Physicist's help, (not to mention all the patient people in the mathematics chatroom) I have got to this expression: $$ i\\hbar \\left( \\int\\limits_{-\\infty}^{+\\infty}{ \\frac{-i\\hbar}{2m} \\dfrac{\\partial^2 \\Psi^}{\\partial x^2} \\frac{\\partial \\Psi}{\\partial x} + \\frac{i}{\\hbar}V \\Psi^ \\frac{\\partial \\Psi}{\\partial x} }dx + \\int\\limits_{-\\infty}^{+\\infty}{ \\Psi^* \\frac{\\partial}{\\partial t} \\frac{\\partial \\Psi}{\\partial x} }dx \\right). $$\nAnd now I'm stuck. What can I do about $$ \\int\\limits_{-\\infty}^{+\\infty}{ \\Psi^* \\frac{\\partial}{\\partial t} \\frac{\\partial \\Psi}{\\partial x} }dx $$\nIn particular how to deal with $$ \\frac{\\partial}{\\partial t} \\frac{\\partial \\Psi}{\\partial x}? $$ With the $\\partial t$ in play I don't know how solve the integral...\nAs before, I really would appreciate hints to get me moving in the right direction more than an outright solution.\nMy working so far\nWe are given $\\left\n$ in the text, which is determined by computing $\\frac{d\\left}{dt}$ and multiplying by $m$.\nLets just start with what we know: $$ \\left\n= \\int{\\Psi^*\\left[-i\\hbar \\frac{\\partial}{\\partial x}\\right]\\Psi}dx. $$\nSo taking the time derivative, $$ \\frac{d\\left\n}{dt} = \\frac{d}{dt}\\int{\\Psi^*\\left[-i\\hbar \\frac{\\partial}{\\partial x}\\right]\\Psi}dx. $$\nWe probably should at this point pause, and listen to <PERSON>, (and <PERSON>). So take out the constants before going any further.", "955" ], [ "We get, $$ -i\\hbar \\frac{d}{dt}\\int\\limits_{-\\infty}^{+\\infty}{ \\left( \\Psi^* \\left[ \\frac{\\partial}{\\partial x} \\right] \\Psi \\right) }dx. $$\n(1) Since the variables t and x are independent, you can bring the time derivative into the integral. You can also use the derivative product rule to get two terms in the integral.\nBringing the time derivative into the integral, gives us $$ -i\\hbar \\int\\limits_{-\\infty}^{+\\infty}{\\frac{\\partial}{\\partial t}\\Psi^*\\left[\\frac{\\partial}{\\partial x}\\right]\\Psi}dx. $$\nThen differentiating with the product rule yields, $$ -i\\hbar \\int\\limits_{-\\infty}^{+\\infty}{ \\frac{\\partial \\Psi^}{\\partial t} \\frac{\\partial \\Psi}{\\partial x}+ \\Psi^ \\frac{\\partial}{\\partial t} \\frac{\\partial \\Psi}{\\partial x} }dx. $$\nNow we have two terms in our integral, let's split em up. Let's consider the left handside first, we have $$ \\int\\limits_{-\\infty}^{+\\infty}{ \\frac{\\partial \\Psi^*}{\\partial t} \\frac{\\partial \\Psi}{\\partial x} }dx. $$\nBy <PERSON> this can become, $$ \\int\\limits_{-\\infty}^{+\\infty}{ \\left(\\frac{-i\\hbar}{2m} \\dfrac{\\partial^2 \\Psi^}{\\partial x^2} + \\frac{i}{\\hbar}V \\Psi^ \\right) \\frac{\\partial \\Psi}{\\partial x} }dx.", "955" ], [ "Note: I have tried to make my answer a little more general, with detail, so that it will be useful for more people.\nThe question is what boundary conditions do we apply to our wavefunction either side of a Dirac delta function?\nIn your example we have the potential $$V(x)=\\begin{cases}\\infty &\\text{ if } x < 0\\ \\alpha~\\delta(x-a) &\\text{ if } x \\geq 0 \\end{cases}$$ We are interested in the boundary conditions either side of $x=a$. What information do we have? Well, due to the probabilistic interpretation of the wavefunction we require continuity of the wavefunction. That is, our first boundary condition is $$(1)~~~~~~~~~~~~\\boxed{\\psi_{-}(a) = \\psi_{+}(a)}$$ where the $\\pm$ subscripts represent the right and left sides of $x=a$ respectively.", "474" ], [ "What other conditions can we set? Well, usually we would ask that the first derivative is also matched either side of $x=a$ (you should be asking yourself why do we do this?), but in this case this is not the right condition to impose. Let's see why.\nWhere does the boundary condition on $\\frac{\\partial \\psi}{\\partial x}$ come from?\nOur wavefunction is a solution to the 1-D time-independent Schrödinger Equation: $$H~\\psi(x) = -\\frac{\\hbar^2}{2m}\\frac{\\partial^2}{\\partial x^2}\\psi(x)+V(x)\\psi(x) = E~\\psi(x)$$ Looking at this equation, we see that we can get a boundary condition on $\\frac{\\partial \\psi}{\\partial x}$ at any point $a$ by integrating it w.r.t $x$ over the region $[a-\\epsilon,a+\\epsilon]$, taking $\\epsilon\\rightarrow 0$: $$\\lim_{\\epsilon\\rightarrow 0}\\left[-\\int^{a+\\epsilon}{a-\\epsilon}dx\\frac{\\hbar^2}{2m}\\frac{\\partial^2}{\\partial x^2}\\psi(x)+\\int^{a+\\epsilon}{a-\\epsilon}dx~V(x)\\psi(x)\\right] = E~\\lim_{\\epsilon\\rightarrow 0}~\\int^{a+\\epsilon}{a-\\epsilon}dx~\\psi(x)\\ \\implies -\\frac{\\hbar^2}{2m}\\left[\\frac{\\partial \\psi{+}(a)}{\\partial x}-\\frac{\\partial \\psi_{-}(a)}{\\partial x}\\right] + \\lim_{\\epsilon\\rightarrow 0}\\int^{a+\\epsilon}{a-\\epsilon}dx~V(x)\\psi(x) = 0$$ where we have used the continuity of $\\psi$ to evaluate the RHS as zero. Note that for any $V(x)$ the second term doesn't necessarily vanish. But, if $V(x)$ is continuous, this term will vanish for the same reason the RHS did, and in those cases we yield the usual boundary condition $$\\boxed{\\frac{\\partial \\psi{+}(a)}{\\partial x}=\\frac{\\partial \\psi_{-}(a)}{\\partial x}}~~~~~~~(\\mbox{when $V(a)$ is continuous at $x=a$})$$ We note that the for example given here, $V(x)$ is definitely not continuous at $x=a$, where it diverges to infinity.", "955" ], [ "What is $\\langle H \\rangle$ in the infinite square well in the state $|\\psi \\rangle = | x_0 \\rangle$, where $0 \\le x_0 \\le L$?\nIn the 1-dimensional infinite square well (with width $L$) the eigenvalues and the corresponding eigenfunctions are $$ E_n = \\frac{\\hbar^2 \\pi^2 n^2}{2L^2 m},\\qquad \\psi_n (x) = \\sqrt{\\frac{2}{L}}\\sin\\left( \\frac{n\\pi}{L}x\\right), \\qquad x \\in [0,L] $$ The general solution of the time-independent <PERSON> equation in the basis of the Hamitonian is $$ \\psi (x) = \\sum_{n=1}^\\infty c_n\\,\\sqrt{\\frac{2}{L}}\\sin\\left( \\frac{n\\pi}{L}x\\right) $$\nQuestion:\nIf the particle is in the state $\\psi_(x) = \\delta(x-x_0)$, where $0 \\le x_0 \\le L$, i.e. the particle is at the position $x =x_0$ at $t = 0$ with certainity, then what is the expectation value of the energy $\\langle H \\rangle$ in this state ? or even what is the probability of getting each of the eigenvalues $E_n$ upon measurement ?\nI don't know if this is the right way but my attempt is as follows:\nI.", "669" ], [ "The coefficients $c_n$ of the expansion using Fourier trick are $$ c_n = \\int_0^L \\sqrt{\\frac{2}{L}}\\sin\\left( \\frac{n\\pi}{L}x\\right)\\delta(x-x_0)\\,dx = \\sqrt{\\frac{2}{L}}\\sin\\left( \\frac{n\\pi}{L}x_0\\right) $$ II. It folows that (I'm not sure if this makes sense) $$ \\langle x_0|x_0\\rangle = \\sum_{n=1}^\\infty |c_n|^2 = \\delta(x_0 - x_0) = \\infty $$ III. The expectation value of the energy is $$ \\langle H \\rangle = \\sum_{n=1}^\\infty E_n\\,|c_n|^2 = \\frac{2}{L}\\sum_{n=1}^\\infty E_n\\,\\sin^2\\left( \\frac{n\\pi}{L}x_0\\right) $$ or differently $$ \\langle H \\rangle = \\int_{-\\infty}^\\infty \\delta(x-x_0)(-\\frac{\\hbar^2}{2m}\\frac{d^2}{dx^2})\\delta(x-x_0)\\, dx = \\cdots $$\nI don't know how to check whether these two expressions of $\\langle H \\rangle$ are equivalent, how does the first converge and how to compute the second ?\nADDED:\nThe first expression should be more completely written as $$ \\langle H \\rangle = \\frac{\\langle \\psi|H|\\psi\\rangle}{\\langle\\psi|\\psi\\rangle} = \\frac{\\sum_{n=1}^\\infty E_n\\,|c_n|^2}{\\sum_{n=1}^\\infty |c_n|^2} = \\frac{\\infty}{\\infty} = \\ ? $$ and I would suggest to get the limit as the limit of the sequence $$ \\langle H \\rangle_m = \\left( \\frac{\\sum_{n=1}^m E_n\\,|c_n|^2}{\\sum_{n=1}^m |c_n|^2}\\right)_{m\\in\\mathbb N} $$ Result: it will not converge", "955" ], [ "Finding $\\langle \\psi_n | x | \\psi_m \\rangle$ for the harmonic oscillator\naketitle\nI need to prove the following for the quantum harmonic oscillator, whose potential is given by $V(x) = \\frac{1}{2}m\\omega^2 x^2$:\n$$\\langle x\\rangle_{n m}=\\left\\langle\\psi_{n}|x| \\psi_{m}\\right\\rangle=\\left{\\begin{array}{cl} \\frac{1}{\\alpha}\\left(\\frac{n+1}{2}\\right)^{1 / 2} & m=n+1 \\ \\frac{1}{\\alpha}\\left(\\frac{n}{2}\\right)^{1 / 2} & m=n-1 \\ 0 & \\text { otherwise } \\end{array}\\right.$$\nAnd I think I am on the right path but I am not very sure how to proceed. I know that the wavefunction obtained as a solution for <PERSON>'s equation and the mentioned potential is:\n$$\\psi_n(x) = \\sqrt{\\frac{\\alpha}{\\sqrt{\\pi}2^n n!}} H_n(\\alpha x)e^{-a^2x^2/2}$$\nWhere $H_n(x)$ is the n-th order Hermite polynomial and $\\alpha = \\sqrt{m\\omega / \\hbar}$.", "955" ], [ "I know that the following holds for Hermite polynomials: $$H_{n+1} = 2 x H_n - 2 n H_{n-1}$$ And therefore: $$x H_n = \\frac{1}{2}H_{n+1} + n H_{n-1}$$\nI also know that these are a set of orthogonal polynomials, since:\n$$\\int_{-\\infty}^\\infty e^{-x^2}H_n(x) H_m(x) dx = \\sqrt{\\pi} 2^n n! \\delta_{nm}$$ Where $\\delta_{nm}$ is the <PERSON> delta. With these things in mind, this is what I have tried to do: $$\\langle x \\rangle_{nm} = \\int_{-\\infty}^\\infty \\psi_n(x)\\cdot x \\cdot \\psi_m(x) dx$$\nNow some constants come out of the integral, and the integral which I am having trouble solving is: $$I = \\int_{-\\infty}^\\infty H_n(\\alpha x) H_m(\\alpha x) e^{-\\alpha^2 x^2} \\cdot x \\cdot dx$$\nAnd taking $\\mu = \\alpha x$ we get:\n$$I = \\frac{1}{\\alpha^2}\\int_{-\\infty}^\\infty H_n(\\mu) H_m(\\mu) e^{-\\mu^2} \\cdot \\mu \\cdot d\\mu$$\nIt is clear that the orthogonality of the <PERSON> polynomials is going to be useful somehow, but I don't know how to keep going because the simpler integrals I obtain always diverge or turn out to be more difficult to solve. Any tips would be appreciated.", "955" ], [ "Does this wave function from <PERSON> book (Quantum Mechanics) violate uncertainy principle?\nI am not sure whether my question count as homework and exercises or not, because I already know the answer. The problem is, I find <PERSON> answer rather unsatisfactory.\nProblem 1.11 (a) Find the Fourier transform for $\\phi(k)=A(a-|k|),~~|k|\\leq a~$ where a is a positive parameter and A is a normalization factor to be found. (b) Calculate the uncertainties $\\Delta x$ and $\\Delta p$ and check whether they satisfy the uncertainty principle.\nThere are many ways to calculate $\\Delta x$ from wave function. One can find it from $\\phi(k)$ or $\\psi(x)$ (wave function in position space) and etc.", "346" ], [ "The easiest way in my opinion is obtaining it from $\\phi(k)$. Note that $\\psi (x)=\\frac{4}{x^2}sin^2(\\frac{ax}{2})$ according to <PERSON>. So in momentum space we have: $$\\hat{x}=i\\frac{d}{dk}~~~and~~~~\\hat{x}^2=-\\frac{d^2}{dk^2}$$ $$=\\int_{-a}^{a}\\phi(k)\\hat{x} \\phi(k)dk=i(\\int_{-a}^{0}A^2(a+k)dk-\\int_{0}^{a}A^2(a-k)dk)=0$$ $$=\\int_{-a}^{a}\\phi(k)\\hat{x}^2 \\phi(k)dk=0$$ $$\\rightarrow \\Delta x=\\sqrt{-^2}=0$$ Which obviously violate uncertainy principle. I asked this from my university professor, he said due to the discontinuity of wave function you should change $\\hat{x}$ such that: $$\\hat{x}=-i\\frac{d}{dk}, ~ -a\\leq x <0 $$ $$\\hat{x}=i\\frac{d}{dk}, ~~~~~~ 0\\leq x <a $$ But it gives me a complex number for average of position! It does not make any sense. Besides it is possible to show to that average of position in position space is also zero\n$$=\\int_{-\\infty}^{\\infty}\\psi(x)\\hat{x} \\psi(x)dx=0$$\nAll wave functions are real, so I didn't use complex conjugate anywhere.\nThis is <PERSON> answer:\nNow, let us find the width $\\Delta x$ of $\\psi(x)$ Since $sin(a\\pi/2a)=1$, $\\psi (\\pi/a)=4/\\pi^2$ and $\\psi(0)=a^2$ we can obtain $\\psi (\\pi/a)=4/\\pi^2\\psi (0)$ or $\\frac{\\psi (\\pi/a)}{\\psi(0)}=\\frac{4}{\\pi^2}$ This suggests that $\\Delta x= \\pi/a$\nWhere did i go wrong?", "402" ], [ "The problem lies on the notation. The state $|\\psi\\rangle$ is not exactly equal to the eigenfunction $\\psi(x)$.\nThe eigenfunction $\\psi(x)$ is formally defined to be the projection of the state to the position basis $|x\\rangle$ i.e. $$ \\psi(x)=\\langle x|\\psi\\rangle $$\nTherefore the eigenstates $|\\psi\\rangle$ are not \"functions\" of position. Similarly, the operators can be represented as differential operators, but a more correct way of doing so is as follows. For this example I am using the momentum operator in the position representation:\nLet $|x\\rangle$ and $|y\\rangle$ be two orthonormal states in the position basis.", "66" ], [ "We note that $[X,P]=i\\hbar$, therefore $$ i\\hbar\\langle x|y\\rangle = \\langle x|[X,P]|y\\rangle=\\langle x|XP|y\\rangle-\\langle x|PX|y\\rangle=(x-y)\\langle x|P|y\\rangle $$ Since $\\langle x|y\\rangle=\\delta(x-y)$, then $$ \\langle x|P|y\\rangle=i\\hbar\\frac{\\delta(x-y)}{x-y}\\equiv i\\hbar\\frac{\\partial}{\\partial y}\\delta(x-y) $$ Which is a property of the Dirac delta i.e. $\\frac{\\partial}{\\partial y}\\delta(x-y) = \\frac{\\delta(x-y)}{x-y}$. Therefore we see that\n$$ \\langle x|P|\\psi\\rangle=\\int dy \\langle x|P|y\\rangle\\langle y|\\psi\\rangle=\\int dy \\bigg(i\\hbar\\frac{\\partial}{\\partial y}\\delta(x-y)\\bigg)\\langle y|\\psi\\rangle $$ $$ =\\int dy i\\hbar\\frac{\\partial}{\\partial y}\\delta(x-y)\\psi(y)=-i\\hbar\\frac{\\partial}{\\partial x} \\psi(x) $$ From this it is suitable to use the representation \\begin{equation} P\\longrightarrow -i\\hbar\\frac{\\partial}{\\partial x} \\end{equation} As you can see, the operator $P$ in a more general sense is not equal to $-i\\hbar\\frac{\\partial}{\\partial x}$, thus the arrow instead of an equality. It is mere a representation.\nNow that we have this information at hand, in truth when some books or lectures say $$ \\frac{d}{dx}|\\psi(x)\\rangle\\langle u(x)| $$ what they actually mean is $$ \\bigg(\\frac{d}{dx} \\psi(x)\\bigg)u(x) $$ Additional notes:\nWe can see the relationship of the momentum and the position bases states as $$ p\\langle x|p\\rangle=\\langle x|P|p\\rangle=-i\\hbar\\frac{\\partial}{\\partial x} \\langle x|p\\rangle $$ which is a first order partial differential equation, solving this gives $$ \\langle x|p\\rangle=\\frac{1}{\\sqrt{2\\pi\\hbar}}e^{\\frac{ipx}{\\hbar}} $$ i.e. the bases are Fourier transforms of each other $$ |p\\rangle=\\frac{1}{\\sqrt{2\\pi\\hbar}}\\int dx e^{\\frac{ipx}{\\hbar}}|x\\rangle $$ $$ |x\\rangle=\\frac{1}{\\sqrt{2\\pi\\hbar}}\\int dx e^{-\\frac{ipx}{\\hbar}}|p\\rangle $$", "955" ], [ "I am not 100% sure why we go from derivatives involving time to derivatives involving position. I will nevertheless thake the rightmost term in (1.29) and start from there. Let us ignore the constants.\n\\begin{equation} \\int x\\frac{\\partial}{\\partial x}\\Big( \\psi^{}\\frac{\\partial\\psi}{\\partial x} - \\frac{\\partial\\psi}{\\partial x}\\psi^{} \\Big)dx \\end{equation} let us use integration by parts where $x = U$ and $\\frac{\\partial}{\\partial x^\\prime}\\Big( \\psi^{}\\frac{\\partial\\psi}{\\partial x^\\prime} - \\frac{\\partial\\psi}{\\partial x^\\prime}\\psi^{} \\Big)dx = dV$. Integrtion by parts says that\n$$ \\int U dV = UV\\Big|_{-\\infty}^{\\infty} -\\int V dU $$ where we are integrating over the entire real line.\nNotice that $dU = dx$ and that $V = \\int\\frac{\\partial}{\\partial x^\\prime}\\Big( \\psi^{}\\frac{\\partial\\psi}{\\partial x^\\prime} - \\frac{\\partial\\psi}{\\partial x^\\prime}\\psi^{} \\Big)dx =\\Big( \\psi^{}\\frac{\\partial\\psi}{\\partial x^\\prime} - \\frac{\\partial\\psi}{\\partial x^\\prime}\\psi^{} \\Big) $ Ignore the constant of integration.", "955" ], [ "$$\\int x\\frac{\\partial}{\\partial x}\\Big( \\psi^{}\\frac{\\partial\\psi}{\\partial x} - \\frac{\\partial\\psi}{\\partial x}\\psi^{} \\Big)dx = x\\Big( \\psi^{}\\frac{\\partial\\psi}{\\partial x} - \\frac{\\partial\\psi}{\\partial x}\\psi^{} \\Big)\\Big|_{-\\infty}^{\\infty}- \\int VdU = $$\n$$ x\\Big( \\psi^{}\\frac{\\partial\\psi}{\\partial x} - \\frac{\\partial\\psi}{\\partial x}\\psi^{} \\Big)\\Big|{-\\infty}^{\\infty}- \\int VdU = $$ $$ x\\Big( \\psi^{}\\frac{\\partial\\psi}{\\partial x} - \\frac{\\partial\\psi}{\\partial x}\\psi^{} \\Big)\\Big|{-\\infty}^{\\infty}- \\int \\Big( \\psi^{}\\frac{\\partial\\psi}{\\partial x} - \\frac{\\partial\\psi}{\\partial x}\\psi^{} \\Big) dx $$\nthe sneaky assumption being made is that the wave fucntion $\\psi$, its derivative and ints comple conjugate all go to zero at infinity faster than the linear term $x$ blows up. If you use a gaussian for $\\psi$ you will see that this is so. Therefore the boundary term is just zero, i.e. $$x\\Big( \\psi^{}\\frac{\\partial\\psi}{\\partial x} - \\frac{\\partial\\psi}{\\partial x}\\psi^{} \\Big)\\Big|_{-\\infty}^{\\infty} = 0 $$\nhence $$\\int x\\frac{\\partial}{\\partial x}\\Big( \\psi^{}\\frac{\\partial\\psi}{\\partial x} - \\frac{\\partial\\psi}{\\partial x}\\psi^{} \\Big)dx = - \\int \\Big( \\psi^{}\\frac{\\partial\\psi}{\\partial x} - \\frac{\\partial\\psi}{\\partial x}\\psi^{} \\Big) dx.$$\nThis should do it. I was not too careful with the integration dummy variables and a few other details but the framework of what you are trying to show is presented here.", "955" ] ]

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[ [ "Improving long range accuracy of rockets without active guidance in flat/minimum arc trajectory\nI am using rockets as a main weapons platform for my vehicles. Currently they are fired from a railgun like apparatus. A rocket is at the center of three rails arranged in the fashion of a triangle. A sabot jacket surrounds the rocket, which is connected to the rails. The rocket motor ignites bringing it up to a maximum burn rate, after that the breaks on the rails disengage and the sabot jacket carries out it out of the rail system. The jacket separates and the rocket flies off to hit its target at an incredible speed. The rocket motor would still be active throughout the flight, stopping only if it runs out of fuel or hits its target. The sabot may rotate, as of now I'm not entirely sure if that would increase or decrease the accuracy of the weapon.\nThe weapon system will be firing both guided and unguided kinetic energy missiles. This question focuses strictly on the unguided solid rod penetrator rocket.\nKinetic energy missiles have a massive benefit in that they can accelerate to high speeds without using complex technologies that require advanced technologies seen in railguns, coilguns, combustion light gas guns etc. They also have a significantly higher upper velocity compared to the upper limit of chemical/gunpowder rounds. Outside of the initial acceleration phase, they greatly out speed even armor piercing fin stabilized discarding sabot rounds.\nInterestingly enough the fuel needed to get such a weapon system to such speeds and velocities (1.5-2.23km/s) to kill in a small portable fashion was created during the days of the Future Combat System and 1980s-early 2000s. Several kinetic energy missiles were created, LOSAT, KEM, CKEM for reference. They observed excellent penetration powers during testing application against even ERA equipped T-72s.", "898" ], [ "The minimum range of CKEM was 200m whereas LOSAT was 400m.\nAll my targets will be engaged at ranges of 1Km+ (maximum ranges for older kinetic energy missiles range between 5-10km using technology from the late 90s to early 2000s), and the maximum speed will be much higher due to in setting rocket fuel sources. The issue I have with such a system is accuracy. In the real world the situation was solved with active guidance. However, my rockets can't use active guidance for multiple reasons. Once it leaves the barrel, whatever direction its pointing at, is the direction in which its going to hit its target. Ideally the rockets should fly in a level trajectory. They won't be doing any maneuvers or top attack of any kind or use any chemical effect warheads (HEAT/HEAT-FS/HE/HESH/HEDP).\nWhat modifications would be needed to make such a rocket more accurate to be able to hit targets at long range (1-10km) without the use of active guidance? Active guidance in this case refers to something like beam riding, warhead seekers, or radar guidance from a command vehicle.\nI am okay with some \"passive\" guidance systems so long as they aren't actively scanning data from outside the rocket itself. For example, keeping track of a rockets angle of attack or speed would be considered \"passive\" in this sense since an onboard computer in the rocket can do this without having to communicate with a command vehicle. But an image/heat seeker would be considered active since its scanning target data to make major course changes instead of course correcting to its initial launch vectors. Preloaded data onto the rocket is fine to set information such as range, elevation, angle, etc. The goal is to stabilize the rocket as much as possible so that it has a linear flight plan, based on the initial vector it left the barrel from. In this sense the \"unguided\" rocket rounds act as tank rounds.\nWhile active guided missiles are obviously better, they're also significantly more expensive and complex to mass produce. A \"dumb\" KEM would cut heavily on costs and past certain speeds would benefit from not having seekers/fragile electronics as they can be damaged by shock/trauma which KEMs are more than capable of doing on launch or even main boost phase.", "234" ], [ "How feasible would it be to build and field a tv/radio guided drone against aerial targets without modern technology?\nI have a constantly moving floating island that is looking to augment its air force against numerous threats in the sky. Having long run out of resources that don't grow out of crystals or biomaterial on the island, the majority of its resources come from attacking and excavating other islands. Islands which may have native hostile life or intelligent life.\nAt times multiple islands may be fighting each other or over the same piece of unclaimed land, so control over the skies around the island is critical. The air force operates a range of aircraft. One of which acts like a fleet defense aircraft. Only it defends the island, hurling long range missiles in beyond visual range combat. It combines a powerful radar, high fuel load, and decent computerized technology (pre 2000s military tech). However, due to limited resources and scales of industry they are unable to field many of these platforms. Furthermore, it takes a lot longer to re arm and refuel (does not use normal jet fuel). The large distances involved compound the situation.\nIn offensive actions it acts as a long-range missile platform, however once it expends its ammunition it cannot contribute any offensive action short of EW. To offset this lack of combat capability, drones carrying a load of missiles have been developed. Essentially missile trucks. Once a fighter expends its ammunition, they circle a drone carrier, link with a drone and fly off with one. Essentially a soft reload of sorts.\nWhile their exists automation on the island, there is no artificial learning, machine learning or deep learning. They are unable to make transistors at such a small level with the necessary computer science to enable truly autonomous aircraft control that is combat rated. As such the drone is only capable of basic auto pilot and preprogrammed holding patterns. Some even use electromechanical computers.", "46" ], [ "More advanced maneuvers require the use of a human operator who is in a parent fighter aircraft who establishes a link to the drone.\nThe human operator is essentially a back seater/weapons system officer (WSO) w/ a slightly extended suite. Using a combination of TV and radio guidance, the WSO flies the drone manually from their aircraft. The fighter's onboard radar handles targeting information for the drone. Once a target is locked on, the WSO executes a fire command, from which the drone will fire a missile. The missiles that can be fired include both active and semi active missiles. During such operations, the fighter won't be pulling any aggressive maneuvers except for defensive actions. It'll stay at distance firing away with missiles, aiding older generation fighters. After firing its magazine, the WSO will fly the drone back to an airship and land it while the fighter circles in a holding pattern.\nHow feasible would it be to build and field such a drone that utilizes TV and radio command guidance against air targets without access to modern technology\nAssume technology (military and industrial) is capped to pre 2000s, there is no contemporary AI control or advanced flight mapping technologies that you'd expect to see on either Loyal Wingman or FCAS' drones. All flight maneuvers short of a pre-planned takeoff or basic holding pattern will be done by a human operator over wireless.\nNotes:\n1. Total fuel load of parent fighter aircraft is of no concern\n2. The drone mounts a forward-facing camera and a few sensors across the aircraft. The WSO gets a HUD and relevant data superimposed onto the view they receive from the drone. Their station is equipped to handle these drones.\n3. WSO/back seater is pilot trained and qualified to fly these drones\n4. The targets these drones will be firing at will range from anything involving primitive aircraft to 5th gen aircraft platforms. While the island in question may not be able to build high transistor density chips, that doesn't mean other islands cannot. There are enough flying based organisms that pose a threat to warrant this aircraft to be sortied against them as well.\n5. Size can vary between something as small as a jet powered drone or as big as an F16.", "160" ], [ "Future therapy/treatment for veterans of near future/ further future mass casualty conflicts\nThe setting I am working on is near future in a sense and involves veterans dealing with the aftereffects and trauma of war. However, in this setting war is extremely deadly even if not always fatal. More so than our current battlefields. For example, the use of loitering munitions is so prevalent that most infantry units operate from armored APCs with heavy active protection systems and dismount only if the situation calls for it. There is some light shielding so tanks, APCs etc. can take a few hits. Short of nuclear weapons (non-factor in the setting), the soldiers from all sides practically threw everything at each other over a protracted conflict that spanned years. Death is either very fast and unexpected via the use of PGMs or large explosives/artillery. Or slow and painful i.e., when armor piercing shots damage vehicles and maim the crew but don't outright kill them immediately because of shielding.\nThe result of this is that there are a lot of injured and physically disabled veterans.", "347" ], [ "By the end of the war, which ended in a stalemate with all sides hanging on by a thread, the majority of active-duty soldiers are heavily injured and or have major war related trauma. While not a majority, a decent percentage of each countries' population was recruited or conscripted during the war. The casualties were horrific regardless. Essentially to the point that the militaries of countries have to wipe away the majority of their armed forces and recruit or conscript from scratch due to the prevalence of severely injured soldiers (think <PERSON> levels of bad, but instead of the old and extremely young its mainly the heavily injured.).\nWith all these returning veterans coming back home there is obviously a major reintegration problem. Especially with how violent the war was. One of the issues is that the fighting didn't really affect civilian areas. Civilians no doubt had their own stressors and issues, but the fighting largely took place off planet. As a result, civilians including the academic/medical community back home have a different and less popular view of the war and the soldiers (think Vietnam).\nGiven the extra level of violence one could expect from close to far future conflicts between peer forces what would therapy/treatment look like on a systemic level. With the sudden influx of mass casualties returning from an entirely different planet at the end of the war, what medical and psychological advancements could one expect to be used to treat such a large group of returning veterans.\nEdit: Focused question based on feedback to focus on future treatments instead of \"upper limit\" on treatments.", "454" ], [ "Realistically overcoming point defenses with starfighters and their role in combat\nI'm developing a game right now focused on starfighter based combat where the character is a pilot of said starfighters. I had intended for bombers to be surgical strike craft, taking out weak points that would otherwise be out of view for opposing capital ships. Fighters would then serve as escort or interception for/against bombers.\nThe big advantage I see to the starfighters and bombers currently designed for the setting are that a great number of them are made for both atmospheric and space combat (some [expensive] models are even capable of re-entry on their own.) They could essentially double as atmospheric fighters in the case of planetary landing.\nIn reality, I'm certain they would be easily picked off by point defenses alone. Most likely a high power laser that could vaporize most of the fighter before they could even get a good visual on their target.\nSo, I wanted to turn here for suggestions on making starfighters a more viable while keeping it mostly realistic and get thoughts on the solutions I've thought of. What are some other realistic means of countering, or at least reducing the effectiveness of point defenses?\nSolution one - Laser-resistant armor:\nA new technology or alloy has rendered the most effective forms of point defense useless against fighters, forcing them to use less reliable means.", "898" ], [ "I don't want to have them jam tracking systems, but maybe their hulls are layered with something that is resistant/reflective to high power light-based weapons such as lasers. And more powerful, larger, lasers that could overpower that defense become too hard to turn quick enough to track. I feel it is a weak option as other point defense systems could easily take their place.\nSolution two - Situational use\nAnother thought was creating scenarios where ships have to fight in close proximity where fighters might shine. The only reason I can think to force capital ships into close quarters would be for the sake of capturing stations and other points of interest that require boarding, but I'm not sure about putting that in every battle. I could see fighters being reserved for exactly those battles and being left in hangar in long range engagements (which from a gameplay standpoint sucks a little bit of variety out of the game, unfortunately.)", "898" ], [ "What are the risks with massive banks of batteries/capacitors?\nIn redesigning a large number of my ships, I've decided that having larger ships generate enough power for FTL was too convenient and made balancing the factions varied FTL methods difficult (both for writing and game development.) To work around this, I'm moving the ships towards having large banks of capacitors/batteries that store energy for later use (FTL or other power-intensive equipment.) The ships would need to recharge off their reactors between jumps/warps.\nThis also presents a new weak point on many of these ships, I think.\nShips are powered by fusion reactors (plural for redundancy reasons) and store the excess power that isn't running the ship into capacitors and batteries for later use. These capacitors and batteries would likely work similar to those we have today but with advances in energy storage density. Fusion reactors have the added benefit of being the \"safer\" forms of nuclear power in that a runaway reaction is not possible as fuel is added on demand and to maintain the reaction.", "284" ], [ "If a system fails and takes away conditions needed to maintain fusion, the reaction ceases. Contained heat and energy might disperse into the local hull, but the rest of the ship would likely survive.\nBatteries would be used for taking over powering ship systems in the case of a local reactor failing while the nearest reactor transitions towards higher capacity of output to compensate.\nCapacitors would be used for systems that require all of that energy in an instant: massive weapons with slow firing cycles and various FTL drives being the two primary examples.\nBoth of these capacitors and batteries would function much like what we have presently, only with advances in energy storage density. Batteries storing energy through chemical reactions and capacitors storing the electrons themselves.\nIf these ships were storing massive amounts of energy, astronomical by our standards since we are talking about faster than light travel, I could imagine damage to these banks causing a catastrophic discharge of the energy contained. Something that would likely vaporize the ship in a near instant along with anything nearby.\nWhat would likely happen if they were struck in combat or something collided with the ship? And are there means to prevent this violent discharge, protect the ship itself from it, or redirect it away from the ship?\nIf it could be directed, I can imagine fleet formations being set up so that friendly vessels are never in the path of these discharges.", "284" ], [ "Not as much of an effect as you think.\nDoing some back of the envelope physics calculations:\nA M1 Abrams tank shells weigh around 18 kg.\nModern capacitors have a max energy density of 9.5 Wh/kg.\n* Assuming all of that shell is capacitor you get a maximum energy released of 171 Wh or 640kJ.\nThe math would get even worse if you only considered the mass of the projectile.\nTo put that in perspective; * Setting off ONE kilogram of TNT releases 4.6 million Joules of energy. * A .50 BMG bullet produces between 14kJ and 20Kj * There is more power in chunk of C4 the size of a deck of cards than in your 18kg tank shell.\nReal world plasma is very different than the plasma you get in sci-fi. To quote @GrumpyYoungMan;\nPlasma isn't special, it's just ionized gas, usually at high temperature but not always (see en.wikipedia.org/wiki/Nonthermal_plasma). Even conventional HE produces plasma (e.g.", "435" ], [ "https://www.researchgate.net/publication/336015137_Study_on_Electromagnetic_Radiation_Generated_During_Detonation which discusses RF generated by plasma during HE detonation) so one could say that HE shells are already \"plasma explosives\". Any damage caused would be because of the high temperature and kinetic energy of the gas, not the ionization, just the same as regular HE does.\nAre you sure you need to do calculations based on your (I'm guessing, limited) understanding of physics? Pretty much every established sci-fi IP that uses plasma weaponry has handwaved the physics and said \"Plasma weapons are effective.\" For instance the super cool bolter round cutout images in 40k don't derive effectiveness from physics. In the game the effectiveness changes as the game gets rebalanced. In the lore it's as effective as the story needs it to be.\nMy advice is when in doubt do what is cool and trust your audience to care more about your cool story, film, comic, or game than they do about doing physics homework. In fact if someone cares enough about your work to take the time to point how you got your math wrong that's a sign that they care enough about it to obsess over it.", "477" ], [ "All of the workable defense strategies I've read thus far assume the space bees are in a tightly packed formation. There is no particular reason for this to be the case, and since they are not idiots I am going to assume they spread themselves over the maximum volume possible. A relatively small sacrifice in delta V will result in very large fleet dispersals meaning that no nuclear weapon will be able to kill more than a single bee, and clouds of dust or sand will not be large or dense enough to materially affect the fleet during transit.\nThe OP says the fully fueled mass of the bees is 3141kg. Using this online calculator http://www.strout.net/info/science/delta-v/ an 80,000 ISP, and 70,000 m/s delta V suggests an unfueled mass of 2870 kg. That gives me a 7E12 joule energy. (i.e. 7 terajoule or 1.6 KT)\nThe total energy of the fleet will be 7E20 joules or 170,000 MT. The bolide which killed off the dinosaurs is estimated to have had 130,000,000 MT of energy, so the bees would have almost 1,000 times less energy if they all get through our defenses.\nThis handy calculator gives you the effects of an individual impactor. http://impact.ese.ic.ac.uk/cgi-bin/crater.cgi?dist=.001&diam=2.76&pdens=261&pdens_select=0&vel=70&theta=90&tdens=2500&tdens_select=0 projectile diameter is 2.76m, density is 261 kg/m^3, velocity is 70 km/s, angle is 90 degrees. The one problem it has is that it assumes an impactor tensile strength of a natural material, whereas these impactors are made from carbon nanotubes. I don't know how to calculate how atmospheric frictional heat loadings affect the material, nor what kinds of tensile stresses result from the atmospheric traversal, but I think it is safe to say the impactors would penetrate to a lower altitude than indicated in this calculator.", "912" ], [ "But since the calculator has the impactor detonating into a fireball at 121,000 meters altitude, I think it's very unlikely that it would reach a low enough altitude to markedly affect the surface before it detonated into a fireball.\nThe other noteworthy takewaway from this calculator is that the fireball energy is only 1/7th the kinetic energy of the impactor. (Presumably the rest is lost to friction prior to this point.)\nThis puts the attack in a very different light. Essentially all of the energy of a fleet attack which was well distributed across one half of the Earth would go toward heating the atmosphere, producing little or no effects on the ground other than loud noises and bright flashes of light.\nIn order to produce any truly dangerous effect, the attack would have to be focused. If the bees fire a dense stream of impactors at selected targets, they can produce deeper penetrations. The initial impactors would produce a partially evacuated shockwave in their wake, through which the following bees could travel with less energy lost to the atmosphere as friction, resulting in lower detonation altitudes (possibly not detonating until impacting with the surface). Also, the thermal flash effects would be concentrated in one area, resulting in arbitrarily high thermal loads in that vicinity.\nPotential strategic impact sites might include the Yellowstone super volcano (possibly requiring the entire fleet to cause any likely volcanic effect here?), nuclear reactors, flash heating attacks on drought afflicted forests in order to cause massive firestorms and nuclear winter effects (nuclear winters rely entirely on sending smoke into the stratosphere via a firestorm), flash heating of crop lands in order to create famine conditions, bioweapon research labs (human diseases are pretty bad, but just as horrible would be the effects of uncontrolled release of novel crop diseases), and oil refining and storage facilities (cripples our economy and contributes smoke to stratosphere).\nOne problem with focused attacks is that they make it easier for the Earth to degrade the attack (with nuclear detonations in space and sand cloud attacks). The goal would be to degrade the nanotube structures to make them break up higher in the atmosphere. The higher the altitude at which the impactor breaks up in a fireball, the less the damage to the surface.\nI think the bees would be smarter to invest in larger and denser but fewer impactors. Carbon nanotubes might be good material for the outer skin (I'm not sure) but the impactors should carry a payload of natural (non-explosive) uranium, tungsten, or other extremely dense material. The impactors should be shaped like arrows, not like pods. They need to lose as little energy as possible on atmospheric friction, and density is the key to this. The impactors should come in a variety of sizes.", "435" ], [ "Very Close Quarters Combat in space\nWhen I saw this question today in the active questions list I thought it would be about one-on-one combat in space. But the question and answers (while still good) were focused on battles between space craft with long range weapons.\nFor this question, I would like to see answers about personal or hand-to-hand combat in zero/micro-gravity would look like. How could someone defend themselves in space? How could you incapacitate an opponent? What about lethal maneuvers?\nFor the outdoor space battles, assume that combatants are in flexible highly tear-resistant suits (although not un-puncturable) with propulsion systems controlled by a non-intrusive method leaving hands and legs free (possibly a brain-computer interface). Propulsion power is low and limited to slow maneuvering before an engagement (i.e.", "46" ], [ "does not have anywhere near the power output of the Iron Man suit).\nI would consider the following scenarios to be conducive to this sort of combat. (sub-questions are meant to inspire, they don't all need to be answered):\n* Heated, personal disputes between community members of an asteroid colony (lethal or non-lethal)\n* Hitting someone for personal reasons is not likely to result in well thought out efficient strikes - might it be dangerous for both parties involved?\n* How might a bar brawl in space play out?\n* Territorial wars between small to mid-sized gangs who are not wealthy/organized enough to purchase and operate battle-ready space craft (lethal)\n* What tactics would be used for say 10-on-10 fights?\n* What simple weapons would be effective (outside only)?\n* One-on-one space grappling as a professional sport, maybe indoors (non-lethal)\n* What would a 'pin' look like in a grappling?\n* If the goal was to force the opponent out of a ring or sphere (given some fixed structures inside which can be used) what tactics would be used?\n* Tactical SWAT teams who don't use ranged weapons to avoid detection from sensory equipment (could be outside or inside). Possibly need to software hack the space suits of their targets so that they don't raise the alarm when the target's vital signs drop off. (lethal or non-lethal)\n* What would a stealthy strike look like to disable a critical piece of enemy equipment?\n* What would a hostage rescue operation look like from a well guarded space vessel?\nGood luck, have fun!", "477" ] ]

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[ [ "The Matrix Reloaded\nAn immediately noticeable step down from the original, from the over usage of sets and green screen, to bland cinematography, to cartoonish levels of stoic circling dialogue eating its own tail of profundity. Yes there are interesting ideas, yes that highway sequence is incredible, yes Trinity, but the first movie balanced spectacle, existentialism, and intense cultural criticism while never losing sight of the message that love for each other is what will actually make us superheroes; Reloaded (and Revolutions further) sacrifices so much heart in their ambitious commitment to a mythos that is neat in theory but probably would have worked better in an Elder Scrolls style game when there is room for long explanation at your own pace vs truncated meta philosophizing and bullet time. If The Matrix was a radical albeit aesthetic nudge to recognize the history of western culture (colonialist cisgendered heteronormativity, whiteness, etc) and the rot of capitalist individualism, the sequels feel like the very product being critiqued (made more apparent when you read about <PERSON> objections).", "387" ], [ "<PERSON>\nThe effects sequences that represent the neural link between possessor and possessed are truly inspired. The physicality of the facial effects and the editing techniques suggest a much better film. As a feature length narrative this is dreadful and manages to be a step backward from the promising, if not cliché, Antiviral. It doesn't help that the son sets up a comparison to the father, aping <PERSON> the elder's masterpiece Videodrome (not only in plot but in elements of the design).", "5" ], [ "But apart from a handful of \"interesting ideas\" (critic speak for how do I justify sitting through this) this is among the more inept indie horror films of the past decade. It is entirely reliant on the visual styles of the day, which I must admit, I find to be suggestive of a cohort of filmmakers more interested in packaged effect than in cinematic expression. Like The Devil's Candy, Hereditary, or Beyond the Black Rainbow this is obsessed with an aesthetic of portent, but lacks the cinematic brain to imagine such an aesthetic. I cannot wait for the era of symmetrical compositions, slow zooms, and synth scores to die as brutal a death as we are subjected to witnessing in these woefully generic films.", "645" ], [ "The French Dispatch\nWhat is the purpose of the artist, to inform, to spread humor snd humility, or to endlessly drone on about drab politics and confusing philosophical questions. In the end, it turns out that the artist is a host to the parasite of the modern masses, but they don't stop to turn the parasites away from running the hosts to the ground. In a year of pain and sadness, <PERSON> has pulled off a masterpiece of wit and contorted it into a comedy, whilst it being an obvious tragedy. <PERSON> definitely enjoys the work of <PERSON>", "378" ], [ "<PERSON>\nAdmittedly, I did not register this as a comedy until 40 minutes in at which point after realizing this everything the film was doing became crystalized and threatened to break the film in two. The mood piece about alienation as an immigrant worker is nearly overtaken by a dead pan humor that is somehow too arch and too subdued, best exemplified by <PERSON> performance that threatens into becoming a caricature every time the film returns to him.", "132" ], [ "Fortunately, the film finds it's footing again at it's closing with <PERSON> mechanic. Very much of a piece with <PERSON>'s Fallen Leaves as a film that perfectly captures the feeling of living in current moment even if it isn't as fully realized as <PERSON>'s film. I imagine this plays better in a theater with an attentive crowd.", "529" ], [ "Fanatic\nI lost count how many times I checked the time\nI think Fanatic is a slow uninspiring drag which is bland and unrewarding throughout majority of it.\nThe ideolic concept of this old woman being a fanatic to religious values is left flat and unexplored beyond the surface level of restricting the virtues of a prisoner.\nAn idea like Fanatic's feels too small for 97 minute run time that felt like a frustrating 3 fucking hours, as a result we get a basic filler narative piled on top of boring sequences of <PERSON> failing to escape the midst of <PERSON> who never shuts up raving on about her dead son no one gives a shit about in the first place.\nThe mystery of <PERSON> is the most interesting part and was anticipating in the finale with his painting and the his alluring spirit but is left waiting in a writing purgatory, no enticing progression in story, repetitive events that posses minimal thrill and lead to nothing.\nSome great acting was no compromise on an idea which wastes it's own time.", "952" ], [ "The Matrix Resurrections\nA Matrix Sequel written as an extended Saturday Night Live sketch, and not a funny one either (if there is such a thing). It's spelled out explicitly early on why this movie was made but you know <PERSON> maybe you should have kept your dignity and just let them reboot the franchise, because this is an embarrassing way of turning something genre defining that you helped create into a joke about how franchises and movie studios work. Even if you focus more on the idea of it being about <PERSON> saving Trinity there is still so much cringe worthy/snooze worthy/down right embarrassing material here. It is truly depressing to believe that such an important film in the Hollywood system has been reduced to this utter shite", "292" ], [ "Orion and the Dark\nReally didn't love the personification of ideas, and honestly feel like no film has touched the magic of Inside Out when it comes to this but it came together in a fun way. It actually weirdly just takes away from the messages of the movie as it's completely obvious what this is immediately, personified metaphors are fun when there's some more layers.", "823" ], [ "I feel like the story is not deep enough to warrant the excessive metaphors.\nWas really shocked at how this looks a lot worse than most animation films releasing at the moment. It looked really cheap especially coming from a large studio.\nI enjoyed <PERSON>'s existentialism riddled script but I don't think he managed to balance being dark and comedic, I don't think children or adults would either get enough out of this, feels both simultaneoulsy made for children and adults and also made for neither. Jokes about Sundance and <PERSON>, who is this film made for?!?", "698" ], [ "Handling the Undead\nIn an already tired genre, Handling the Undead aims for a more contemplative and somber face than what we’re used to with said genre. The standouts here being the music and atmosphere, one must think such a devotion to visuals would garner strong staying power, yet such was not the case. It’s grief observed, through the lens of dark corridors and isolated pastures, asking the singular question, “if you had one more chance to talk to your loved one, what would you say?”.", "831" ], [ "Throughout the runtime I discovered the film wasn’t exactly interested in exploring this question through a vessel or character of sorts, as it’s practically nonexistent. In the end I was left starved, yearning for a connection. A film with a pulse that slowly fades into obscurity.\nAsk me in a few months and I’ll say, “Oh yeah I forgot I watched that”.", "236" ] ]

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[ [ "Help needed - Writing a novel in third person\nI'm writing a fantasy story in third person and I'm not that confident if I'm doing it right.\nI noticed I'm using the word \"he\" so often (the character's guy by the way) and I'm afraid that I'm \"telling\" more than \"showing.\"\nBelow's a tidbit of my chapter 1\nCold drops of water falling from the ceiling prevented <PERSON> from falling asleep. Each time his eyes were to droop, a single drop of water would fall on his nape, the shivers pulling him back to reality. And each time this happened, his eyes would always meet with the oil lamp on top of a wooden table a good two meters away, its red-orange and yellow flame casting funny looking shadows all around the dark and damp cellar he was in.\nHe would’ve done something about it—but with his hands bound to a chair and his mouth gagged with a cloth, he couldn't do anything much.\nIt might have been hours already since he was brought here; he couldn’t tell exactly. But judging on how soaked his tunic was, it could have been more. The room had no windows; he could've used sunlight to tell the time.\nSpeaking of time, he had a pocket watch with him. Where could it be? Did he dropped it? Or was it taken?\nNo windows. No sunlight. No watch. Great. At least the faint, festive-like merriment from the outside passed through the thick walls, making him feel he had some company.\nHow did I end up in this place again? He squinted at the flame of the oil lamp, as if it would spout some answers.", "624" ], [ "He wanted to scream for his captors to come down and answer his question—and demand for his release; the cloth was doing its job properly.\nSo, no other choice but to rely on good old memory—even if it was currently a dud.\nHe closed his eyes and rummaged his memories for any possible clues.\nNothing—still. What came about was a faint yet sharp throbbing pain from the back of his head.\nMaybe <PERSON> should stop; he'd been doing the same thing since earlier but always got the same result . . .\nThe pain made him wince. A concussion? Aside from the memory loss, there was confusion. He also felt he was out for a swim in the ocean . . .\nHope it’s mild. He was urgent to remember everything—and fast. He closed his eyes and focused on sleeping instead, ignoring the water falling water on his nape, the sensation of his shirt sticking to his skin. Maybe if he slept—maybe if he rested his mind—everything would come back.\nBut his plans of some shut-eye and relaxation got scrapped when the door flew open.\n“Damn it,” he cursed through gritted teeth after nearly falling off the chair.\nAm I abusing the \"he\" in this? Is it too filter-y?\nAny further suggestions to help my story go better?\nNeed your help on this guys.\nThanks ever so much! :)", "624" ], [ "Vision/dream as an effective opening?\nI'm looking for opinions on the effectiveness of this opening scene. It's a vision, not that he knows that at first. He thinks it a dream and won't quite act on it straight away. The vision was given to him by a sentient alien. It's basically the first of a few visions meant to kick start a bit of an adventure sci-fi plot.\n<PERSON> opened his eyes. He saw nothing though he could hear his breathing plainly and the beating of his heart thudded as if he were holding it up to his ear. The air, if there was any, felt as clean as the air in an untouched forest. Slowly, his eyes adapted to the dark and he saw the shapes of jagged spikes of rock in the distance; black and rough yet lit up by a ghostly white light. They were arranged like a passage way, reaching upward until they could no longer be seen.\nHe blinked, a subconscious automated blink, yet now stars shone bright in all directions. He felt like he was floating in space; a void of nothingness littered with sparkles further away than he could imagine.\nHe had a mind now to seek out the passageway. He tried to walk though he felt weightless in the vastness of this starry void, yet he knew somehow that he was moving forward.", "624" ], [ "Or was it moving to him?\nStrangely, he felt at peace, curious even, and didn’t fear what had become of him. In fact, he wasn’t even aware of what he had previously been doing.\nEverything disappeared.\nBefore he knew it, the sound of the garbage truck hit his ears, the sun blinded him and he felt the hard cement underneath his feet. Gravity took hold and he fell to the ground, disoriented. Reality came back to him, reeling his mind in from the far off place. Birds, trees, people passing by, staring at him on the ground.\nSci-fi setting: humans in the far future, no aliens as they thought there might be, a little like a Star Wars type setting (no aliens though). I.e. normal life can be gritty, rich people, poor people, themes from modern society etc.\nStory brief: beacons are found, they signal an onslaught from an alien species that seeks to reclaim \"their\" galaxy. they left a long time ago to end a war with the species of alien this \"vision-giver\" is. The beacons were meant to signal the fact that another race had tried to inhabit the galaxy. They don't like this. Greedy aliens in other words.", "1012" ], [ "Fairy tale princess turning suitors into stone\nI read this fairy tale when I was a kid, around 30 years ago. I've now tried searching for this story, checking the usual suspects (brothers <PERSON> and <PERSON>), but haven't found anything matching. I'm almost starting to believe I've imagined the whole thing... So here's the story:\nOnce upon a time there was a king of a small/poor kingdom, and he had three sons. Since they were so poor, the king decided that one of the princes should marry the princess in a much larger/richer kingdom. The problem was that this particular princess was very picky, and also had magical powers. So any suitors she didn't like, she would turn into stone statues.\nThe princes went to the princess' castle, and entered it one at a time (maybe only one prince was allowed in per day?).", "992" ], [ "The garden of the castle was full stone statues, all the previous suitors.\nSecretly, the princess had disguised/turned herself into a maid so that she could observe the princes before meeting them officially. The first (and of course the oldest) prince went in first; he was certain that the princess would be very impressed by his strength and fighting skills. He of course treated the maid very poorly. Needless to say, the princess turned him into a statue.\nThe second prince didn't do any better.\nThe third prince was very uncertain of himself, I think he discussed with the maid that he didn't really want to do this, but had to try in order to save his poor country. If all three princes were turned to stone, their kingdom would be ruined. He also treated the maid well.\nI believe the maid turned into the princess right there in front of him. I guess they got married, and possibly she brought back to life the other too princes (maybe even everyone she had turned to stone?). And they lived happily ever after.\nThis story to me seems to be a bit more modern than <PERSON>/<PERSON>; the princess decides herself whom she wants to marry, and there are no animals featured.", "992" ], [ "A group of 10 walk into a relatively popular hole in the wall—use our bathroom then bounce. But apparently one of them is super “famous.”\nA couple walks into my tiny ass place asking for a table of 10. We were empty luckily so I kindly pushed a bunch of tables together happily to accommodate. I asked if they wanted drinks in the meantime. They ask for a round of waters.", "314" ], [ "I pour and gather 10 waters.\nA few min later the rest of the party walks in—almost nobody acknowledges me or says hi.—I ask if they want other drinks or if they wish to order—-They barely acknowledge me again.—say no—\nMeanwhile I watch everyone use my bathroom.\nI try to take the order from the table again. They all just walk out. Not saying sorry or bye or anything.\nAmidst this one customer acknowledged that the one guy was famous and yelled it out loud. But no one was there except the groupie and my staff. Maybe thru were turned off by this or maybe they were non humble users?", "314" ], [ "How to describe an angry voice in dialogue?\nI've been looking for a word to describe this tone of voice for a long time but never came across it. Now let me just spread a pinch of context. It's a first person novel, and our protagonist is very emotionally conflicted within. Dead parents, dead friends, blames himself etc. The only thing he has left is his younger companion who he cares for like an extremely over-protective older brother. Our protagonist is responsible (involuntarily responsible) for some earthquakes (long story), and his younger companion at this point in the novel questions if he himself was responsible for it.\nThis is how it goes...\nHe didn’t say a word, as he stared motionlessly straight ahead. He was doing that thing where he overthinks.\n“Stop overthinking. I’ve told you if you keep doing that you’ll get grey hairs.”\nAll of a sudden his eyebrows curled against each other, and his eyes widened with grief, “Please don’t tell me I caused that earthquake?” he whimpered.\nHearing this, I dropped to my knees, and grabbed his face, “Have you absolutely lost your mind?” I yelled.\nOK. So the final bit of dialogue where the protagonist asks \"Have you lost your mind,\" is actually the part I'm struggling with here. He does't actually yell.", "522" ], [ "His voice is more like a throaty growl, as if to convey some frustration as well. Hearing this from <PERSON> (younger companion) just turns his world upside down, because he would never allow his naive younger counterpart to step foot near the earthquake. Yeah, so instead of \"I yelled,\" what the hell is that word. You ever watched the dark knight... where <PERSON> goes to the joker \"Where is she?\" in that interrogation scene. Well it's a voice like that, but obviously with a bit less aggression. A brooding voice. God, what's the damn word?!\nAnyway, thanks if you take the time to read and/or answer my question, and sorry for my panicky tone. I get super worked up over minor word haha.\nOh, and one last thing. I feel like I could have simulated the \"I dropped to my knees and grabbed his face,\" a little better. How do I describe holding <PERSON>'s face in urgency?", "522" ], [ "Work the Spring\nThere's a book that I read several years ago that I'd like to find. However, I cannot remember enough about it to find it myself. Neither the title nor author remain in my mind, nor any keyword or phrase that's unique enough for the Grand Google to nail for me. Hence my desperate plea here.\nIn the book, there is an interstellar civilization composed of several power blocks. The entire civilization did not fill the galaxy, but it did span several stellar systems. Maybe 10s or 100s.\nI seem to remember that one of the civilizations was a decentralized group referred to as the Brotherhood and they seemed to have been keen on preserving old learning and political ideals.\nA derelict alien spacecraft from outside all of this had been discovered and at least two of the power blocks sent ships to recover it. I don't recall if they knew at the time about the power the alien ship had, but they must have had some clue since there was some urgency in capturing this ship.\nOne of the ships sent to capture the Alien craft was commanded by somebody who was rather shaken up, to say the least. He had had some big trauma in his past (like... the last ship he captained was annihilated with all hands.) so he was kinda bummed out about things and wasn't really putting his heart into getting this done. He was assisted by the ship's AI who had a lot of soul-to-soul chats with the captain, and at one point almost relieved him of command because he was just not getting the job done. I think the ship's name was Boaz. These were the \"good guys\".\nThere was at least one other ship sent from the \"bad guys.\"\nThe alien craft had some remarkable powers. The interior volume was apparently infinite and the operators could see and manipulate anything in the universe.", "1012" ], [ "There might have been some example given where all the rats somewhere were found and disposed of.\nWhoever had control was tempted by the ole absolute power corrupts absolutely problem, but nobody but nobody could stop them because of their power. They could eat and multiply within the ship and become real bad-asses. But alas... (or hurray, depending upon which side you're one) everything fails eventually, and whoever controlled the ship would eventually succumb to some horrible end. Whereupon the ship became derelict again until some other lucky race found it and repeated the cycle.\nThe ship had an AI that was real interested in taking the power for itself, but there was some mechanical, spring-loaded, mechanism outside of its control that needed to be worked in order to execute power. The AI apparently never figured out how to \"work the spring\" and this made him crazy angry.\nThe ending is equally foggy for me. I'm pretty sure the good guys got the ship. They agonized over what to do with it. Apparently it was indestructable and nobody wanted to taste the temptation of all that power. In the end they dumped it on the surface of a neutron star. There it sat forever more, probably with the crazy AI really pissed off about being there.\nIf you've read this book, you'll recognize it immediately from these clues. I'm looking forward to finding out the name of this book. Thanks!", "1012" ], [ "I cannot figure out the exact genre (and target audience) of my book\nFor more than three years, I've been writing and re-writing my novel involving immortal characters.\nNow I'm finally gathering courage to write a query letter and begin searching for agents. My problem is that I don't know what kind of agents to contact, as my book seems to fall somewhere in between genres.\nWithout actually getting into the plot, my book is an ensemble piece involving seven immortal characters, some who have lived merely decades, others centuries or millennia. The setting is contemporary (2018, mostly inside a hotel). The book borrows a lot of tropes from the mystery genre, especially from traditional mysteries (a murder in a confined space where all the characters know and suspect each other, lots of red herrings, a fair challenge to the reader where all the clues are presented throughout). The central question is not a whodunnit, however, but a whydunnit and it involves something related to the characters' condition as immortals (not the origin of immortality itself).\nHere's the difficult part. These immortals are simply long-lived characters who come back to life upon death; nothing sets them apart from normal people besides their prolonged existence. They don't have any special powers. There is no magical system inside the story. There are no other paranormal beings inside the narrative (think ghosts or vampires or werewolves).", "775" ], [ "Thus this can't fall into the paranormal mystery subgenre.\nI've turned to fantasy too, but most subgenres that seemed somewhat plausible (contemporary fantasy or urban fantasy, for example), seemed to be quite heavy with the supernatural elements; my book isn't. If anything, it has a pretty rational approach to the issue of immortality.\nSomebody in my writing club suggested magical realism. The problem is that this genre is about the complete opposite of my book in terms of tone (since it involves a certain mysticism, languid pace and flowery prose). My book is fast-paced, full of snappy dialogues and does actually treat immortality as something special, rather than a natural occurrence.\nI'm afraid if I pitch my book as just a mystery, most agents/publishers/mystery readers will be turned off by the supernatural element. If I pitch this as fantasy or paranormal mystery, they will be expecting magic and paranormal beings. I don't know enough about SF subgenres to see if there's anything that fits, as I've only read a bunch of classic SF novels. Thus, I can't seem to figure out my audience either.\nThoughts? Also, are there any other books that fall between similar genres that you could tell me about (mystery with a slight supernatural twist)? It might help me tremendously, as I'd have a starting point in seeing what kind of audience these books attracted.\nEdit: My book is somewhat similar to Death Note in that the supernatural element is more of a plot device/means for the mystery to happen, not the mystery investigated itself. If you suspend your disbelief and accept that Shinigami/Death Notes (or in my case, immortality) exist, then the mystery itself focuses on a (series of) murder(s), involving humans and caused by humans. That's one of the extra reasons why I hesitate to call this fantasy.", "59" ], [ "Ensemble cast novel - pitch and synopsis\nMy mystery novel features an ensemble cast of seven characters. Since I can't talk about all of them in the short span of the query letter, I've decided to focus on the antagonist. He's the main driving force behind the plot and despite appearing the least, he's ever-present in the minds of the other characters. Of course, I'll still mention in the letter that there are multiple POVs united in theme.\nThis, however, leads me to two issues.\n1) Right now I've written a synopsis of almost 600 words where all the characters appear. The other six all influence the main plot and I can't really pick one out and eliminate him/her without losing something crucial to understanding the story. However, I'm afraid the agent reading the synopsis will have a difficult time remembering who is who. Is there an efficient way to make the agent care about each character in such a short span? Or should I do the same for the synopsis - focus on the antagonist and mention the others as the group opposing him? Thing is, they only learn to act as a group at the very end by opposing the antagonist...", "248" ], [ "before that, each does his/her own thing inside interwoven alliances.\n2) My very first chapter is not from the antagonist's POV. The first chapter is more of a short, 450-words event that triggers the main plot (kind of like the victim of a murder mystery dying on the first page, but with a slight twist).\nThe second chapter is from the antagonist's POV and how he plots the entire action that will further occur in the book. It references the event happening in the first chapter.\nThere are some agents I've stumbled upon who only request the first chapter. Should I rewrite my second chapter (featuring the antagonist's POV) as the first one? I feel like something from the book's voice/atmosphere/theme/understanding of the first chapter's POV character will be lost that way, even if it can somehow be worked into the plot.\nEdit:\nI guess I should have cleared some things and reworded my questions better.\nI can't combine the first two chapters. My book follows a pretty strict internal logic where each chapter is from a different character's POV. Chapter 1 focuses on character A and triggers the events in the book. Chapter 2 focuses on character B (the antagonist) who decided to hurry the entire plot of the book because of what happened in chapter 1.\nI could take out chapter 1 since I already mention the event in chapter 2, but I'd rather have it shown for clarity than merely mentioned.\nMy reworked questions are these:\n1) Would seven mentioned characters in a synopsis be too much/too difficult to track? Is there another way to avoid this confusion other than simply labeling some of them as \"the group\"?\n2) Since in my (much shorter) query letter I focus on the antagonist (and lump the other six characters as \"the group\", for space constraints), and I do mention it's an ensemble cast, would an agent automatically expect the first chapter to be from the antagonist's POV? And since it isn't, would that be an instant rejection?", "775" ] ]

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[ [ "<PERSON> gave some good information in his answer. Not only some numbers but how to get the numbers. I would like to add to it.\nThe approach I use is different from <PERSON>'s. I try to explain it here. To get acceleration at elevator foot the model subtracts $\\omega^2r$ from $GM_{planet}/r^2$ to get net acceleration. If a moon is the tether anchor, $GM_{moon}/r_{moon}^2$ is also included, whether this acceleration is added or subtracted depends if the tether is above or below the moon.\nThis net acceleration times kilograms gives the newtons payload exerts. This sets the thickness of the first length of zylon. The next length of tether is thicker as it supports the first length as well as payload. The model chops the tether into a 1000 lengths.\nHere is a screen capture from my look at a Mars elevator:\nIt is reassuring to me that my numbers aren't much different from Rominger's. For a safety factor of one, Rominger gives a Zylon taper ratio of 12.449 (vs 13 for my model). For a safety factor of three he gives a Zylon taper ratio of 1929.560 (vs 2016 for my model).\nMy model based on <PERSON>'s spreadsheet also gives ratio of Zylon tether to payload mass. For a safety factor of 1, you'd need 154 times the mass in Zylon as the payload being lifted. By \"payload\" I mean the elevator car and contents. The elevator car would need its own power source and engines.", "234" ], [ "So the actual cargo would be even less.\nWith a safety factor of 1, the slightest nick or scrape will cause a break. Given the large length of this elevator, I'd expect breaks to be frequent. I would not risk valuable cargo on such an elevator, much less human lives.\nGiven a sensible safety factor of three, tether to payload ratio would be 51,824.\nAnd this wouldn't be the entire elevator. There must be tether and a counterweight above Mars synchronous orbit to balance the downward newtons exerted by the lower elevator.\nA Zylon Clarke tower for Mars is implausible.\nHowever I don't write off the notion of Mars elevators. Mars equator isn't the only place to anchor an elevator. There are a number of scenarios I look at:\nLower Phobos Elevator\nUpper Phobos Elevator\nDeimos Elevator\nI am excited about elevators allowing a Zero Relative Velocity Transfer Orbit (ZRVTO) between Phobos and Deimos:\nTaper ratios and tether to payload ratios for these two elevators are quite modest:\nExtend the upper Phobos elevator and you can fling payloads to the Main Asteroid Belt as well as towards earth. And without prohibitive tether to payload mass ratios.\nExtend the lower Phobos elevator 1400 kilometers and you can drop payloads into orbits where periapsis passes through Mars' upper atmosphere. A few periapsis drag passes can circularize at low Mars orbit with a velocity of about 3.4 km/s. EDL would be easier than the 5.5 km/s atmospheric entry a payload incoming from an earth to Mars Hohmann would experience. Especially if the descent vehicle had some propellent and reaction mass from Phobos. Mars EDL could be considerably easier. Given a safety factor of three, tether to payload mass ratio would be .33.\nCan a Zylon Phobos elevator descend all the way to Mars upper atmosphere? If so, tether foot velocity with regard to Mars would only be .6 km/s. That's only about mach 2, the Concorde did that. But alas, given a safety factor of three, tether to payload mass ratio would be 638. I don't think a lower Phobos Zylon elevator 5,800 km long is practical.", "234" ], [ "Sounds like a system of space planes that operate in the style of the railway system in the early 20th century. Since you said you already had space elevators in place, then you would need a series of space stations that act as rail stations near the elevators. The plane would dock at the station, which gives you quick turnaround time since they never enter an atmosphere. Since everything is in space the space station could be multilevel allowing several planes to dock at once.\nAs far as propulsion, I don't have an exact method, yet, but I know how to meet the \"2 days to Mars at closest approach\" requirement. An engine that is capable of sustaining 1g (Earth normal gravity) of constant acceleration will get a plane from Earth to Mars, assumed 65 million km separation, in 1d 21h 13m 1s. I would love to take credit for figuring that out, but alas, I can't. Check out How fast will 1g get you there? for a really great set of charts, graphs, and travel times. Somebody figured out all the travels times from Earth to each major body in the solar system.", "947" ], [ "That time is for constant acceleration for half the trip, then the ship flips a 180 and does a constant burn for deceleration.\nAnother benefit of constant acceleration is that it provides Earth normal gravity to the passengers and cargo. For more about this see Space Travel Using Constant Acceleration.\nAs I mentioned in the beginning, I would model the entire system around the railway of the early 20th century. Through a series of transfers, a person could travel across the US with little fuss.\nConstant acceleration even works for interstellar travel as well. It would take 1 year + the number of light years to reach any given star. So Alpha Centauri would take 5.2 years since it's 4.2 light years away.\nWhile I'm writing this I thought of a possible propulsion system, an EM Drive or an RF resonant cavity thruster. I know next to nothing about the science of the drive, but my understanding is that it's a \"fuel-less\" drive system. An engine produces an EM field, which it needs to run the lights and whatnot anyway, it diverts a portion of the EM to the propulsion system and it produces thrust. Anyway, it's a thought.", "947" ], [ "So long as we're not bumping into a logistic growth ceiling, I don't see a strong incentive to leave our solar system\nAlong with generation ships comes the assumption of a non solar power source and the technology to engineer closed ecosystems-- the Main Asteroid Belt would be open to real estate development.\nI see several logistic growth ceilings here. I suspect it'd take centuries or millennia to fill the Main Belt. From there the Hildas are natural cyclers between the Main Belt and Sun-Jupiter Trojans. (See this vid where first half shows <PERSON>, 2nd half Trojans). When the Main Belt and Trojans are filled up, there's the Centaurs as well as moons of gas giants. After those are filled comes the Kuiper Belt. And then the Oort Cloud.\nBy the time we fill the Oort, our civilization will probably have many millennia of experience building biomes from ice balls as well as using fusion power.\nGiven a civilization with this infra structure and capabilities, I'd construct the generation ship in the Oort. On the boundaries of the the sun's gravity well, it only takes a small burn to drop the ship to a perihelion deep in the sun's gravity well.\nIt'd take a few centuries for the ship to fall from the Oort to the inner solar system.", "99" ], [ "But given city states throughout the Oort, spending centuries dwelling in artificial biomes is already the norm.\nWhen 1 A.U. from the sun, the ship would be traveling about 42 km/s. If perihelion is within .1 A.U. from the sun, perihelion speed is about 133 km/s. Doing the burn near the perihelion can give a substantial Oberth benefit. If the ship does a 55 km/s burn near perihelion, it'd pick up 133 km/s Vinf.\nOf course 133 km/s is only .0004 C (speed of light). It would take around ten millennia to reach Alpha Centauri and longer for other neighboring stars.\nIf the ship had a drive capable of reaching .1 C, solar Oberth benefit would be of little consequence. In this case I might depart directly from from an Oort object a light year or two out -- as close as possible to the destination star.", "99" ], [ "Ditch Everest. Switch to Chimborazo in Ecuador. Two reasons: 1) Because it is closer to the equator, it's peak is actually farther from the center of the Earth. 2) Because it is closer to the equator, you get more of a boost from rotation of the Earth. Everest at 29.59 degrees North loses almost 14% of the rotational velocity.\nSo launching from Chimborazo gets you additional altitude, and about 223 km/hr extra launch velocity.\nThe structure you have envisioned is massively beyond our current tech. At both ends.\nDigging a slanted tunnel roughly 100 km long is getting to silly proportions. The deepest mine right now is 4 km deep. This is getting pretty close to the limits of our tech right now.\nThe truss you envision holding the launch tube is grotesquely beyond what we can build now.\nThe launch energy needs to be supplied. You need electromagnets up the length of the tube. The energy they need to supply, assuming a constant acceleration, increases as the speed increases. So you need to run gargantuan power cables up the structure as well.\nYou might get someplace by forgetting the extension above and below the mountain.", "234" ], [ "You could have some sort of electromagnetic launcher that pushed a sled that carried your orbiter. Assuming a 50 km track and only 1g, you get 1 km/s in 100 seconds, pretty close to Mach 1, up the mountain. This is fast enough that the sled could detach and the orbiter take over its own burn. The first 25 km or so of the track would be level then curve up the mountain.\nThere are lots of variations on this. For example, the sled could also be a rocket motor that acted as a first stage. Or you could amp up the acceleration up the hill. At 4 g you get pretty close to Mach 2, in 25 seconds.\nYou can get an idea of what you are gaining from launching from the mountain. At 4g you are basically getting the first 25 seconds of rocket power from your launch sled. Suppose you were able to build the truss and extend the ramp another 50 km. This gives you only about another 10 seconds. The part on the mountain might be worth it. Building this currently-impossible truss seems to be a diminishing return.", "234" ], [ "I'm following <PERSON> direction of thinking.\n1. Mars and Earth orbit the Sun. A single blow can't put Mars into path where it would gradually decrease its distance to Earth for 300 years.\n2. One could attempt to put Mars onto an eccentric orbit intersecting with Earth's orbit. That would require a knock of velocity of at last 2500 km/h (calculations below), thus quite some more than 21 km/h. Mars would then intersect the Earth's orbit in less than a year. Depending on the initial positions of the planets on their orbits the collision could occur during the first intersection or one of the further ones. If however they would not collide for 300 years, the Earth's orbit could be still perturbed by the gravitational force of Mars, which by itself could have catastrophic results. Predicting the details would require a complex simulation.\n3. If you want to postpone the collision for 300 years, I would propose to knock Mars away from the Sun, so it would cross Neptune's orbit and come back after 300 years to hit the Earth. One still would need to take into account possible interactions of Mars with the outer planets and perform very precise calculations, but that might be easier than keeping Mars just next to the Earth without a collision for 300 years. The knock velocity to the planet would need to exceed 11500 km/h so even more. An advantage of this method is that depending on the planets position the recoil may put the protagonist into virtually any spot in the solar system you want, including the Earth or its Moon.\n4. As the others pointed out, if the protagonist transfers momentum to the planet, it receives the same momentum in the opposite direction. For 2500 km/h knock on Mars a 100kg protagonist would receive energy of 16·10¹⁵ GeV per each nucleus of his body.", "921" ], [ "This is a lot. That's way more than any energy ever produced in laboratory or observed in nature. That's a hypothesized energy of Grand Unification (https://en.wikipedia.org/wiki/Grand_unification_energy). The act of knocking would be extremely violent. Complete disintegration of any molecular and nuclear structures, production of any known and perhaps unknown particles, maybe even black holes.\n5. Some suggested that the knock would destroy the planet. Maybe. The energy of the knock described in point 2 is 39·10³⁰ J, while Mars binding energy is perhaps 5·10³⁰ J. Some matter would follow in the desired direction. It's difficult for me to speculate how exactly it would turn out.\n6. Once the protagonist lands on another target planet or moon, it transfers its momentum to it, causing similar level of destruction and orbital perturbation as that done to Mars. As the others pointed out, it would violently interact with any matter on its way, and even with cosmic background (see: https://en.wikipedia.org/wiki/Greisen%E2%80%93Zatsepin%E2%80%93Kuzmin_limit).\nMaths. I'm sorry if there are any mistakes, but note we're in the regime where adding or deleting a zero wouldn't change the conclusions.\n1. Knocking Mars towards the Earth The total (potential and kinetic) energy of a planet with mass m orbiting around a star with mass M is $$E = -G\\frac{Mm}{2a},$$ where a is the semi-major axis.\nAssuming Mars following a circular orbit, $a=R_\\mathrm{Mars}$ (distance between Mars and the Sun), $$E_\\mathrm{Mars} = -187·10^{30} \\mathrm{J}.$$\nFor elliptic orbit between the present Mars and Earth's orbits $a = (R_\\mathrm{Mars} + R_\\mathrm{Earth})/2$, $$E_\\mathrm{Mars-Earth} = -226·10^{30} \\mathrm{J}. $$\nThe knock corresponds to change of the energy by $$\\Delta E = E_\\mathrm{Mars-Earth} - E_\\mathrm{Mars} = -39·10^{30} \\mathrm{J}.$$ As the potential energy remains constant, $\\Delta E$ corresponds to change of the kinetic energy only.\nThe orbital velocity of Mars is $v_\\mathrm{Mars} = 86430$ km/h, it's initial kinetic energy is $E_\\mathrm{k} = mv_\\mathrm{Mars}^{2}/2$, and final kinetic energy (just after the knock) is $$E_\\mathrm{k} + \\Delta{E} = m\\frac{(v_\\mathrm{Mars} + \\Delta v)^{2}}{2}.", "921" ], [ "Good thing you've got fusion plants\nBecause you're going to need a lot of energy. Of critical importance is the ionization energy of all the elements. As plasma contains normal elements stripped of their electrons, enough energy will need to be pumped into each trash cube to liberate enough electrons to form a plasma.\nThe energy required to energize/plasma-ize 10m^3 of random garbage will be immense. At the low end, let's continue consider hydrogen. It takes 1312 kJ/Mol for complete ionization. But hydrogen is easy. It's already a gas.\nIron is trickier. It's a solid and does not yield energy through fusion. Iron's ionization energy is 762.5 kJ/Mol for the first electron. Ionization energies rapidly increase for each electron there after.\nI don't know if iron has to be heated to boiling before it can turn into a plasma. If it does then the energy requirements for this reactor are staggering. Assuming linear specific heat values at all temperatures of 1kg of iron of 449 J/kg K; it takes 1407166 J to boil 1kg of iron. Add in the heat of vaporization and it gets even more expensive.\nReactor Design Considerations\nThere's a couple things you'll need to account for in this reactor.\n* Don't let the plasma touch anything. I've seen temperatures of 30,000 Kelvin in the literature. With the energies under discussion, the plasma temperatures may be considerably higher. Normal matter does not perform well when hit with high energy atoms.", "435" ], [ "This is a long standing problem in fusion power plants under development now.\n* This is not fuel. Anything iron and heavier does not yield energy when fused.\n* Injecting cold matter into this reactor will require ridiculously high energy flows to sustain. Each 10m^3 will need to be heated to plasma temps, which will vary wildly from cube to cube. As mass leaves the plasma chamber, it will take thermal energy that must be restored in order to maintain the plasma.\n* The reactor must contain the rapid expansion of gas phase products. Water expands 1700x when turned to steam. Other solids or liquids may expand even more. Not only must the reactor contain the expanding gasses but also the high speed chunks of arbitrary mass accelerated by those products. In other words, without preprocessing, each cube is a 10m^3 fragmentation bomb.\n* Watch out for the really caustic elements such as fluorine and chlorine. These elements aren't bad when bound to other elements at room temperature, but this reactor is not normal. Special precautions will have to be taken or the reactor may eat itself.\nDesign trade-offs\nOkay, so somehow the reactor works. It separates each element and doesn't destroy itself. You've expended an enormous amount of energy to get a very hot gas. Well done!\nHowever, you now have a big hot cloud of random elements that need to be sorted, cooled and turned into products that can be sold. How will you sort these? How will you prevent unhelpful chemical reactions when the atoms cool down?\nHaving done a little research into hydrocarbon plasmas, I can say without a doubt that this area is crazy complex and very hard to manage, even with single element plasmas. This reactor must accept all elements in any ratio or quantity. This is the pdf manual for a real life plasma calculator that only does one element plasmas. All of those input variables will change between batches and perhaps within each batch.", "435" ], [ "You would need:\nEnergy: Nuclear power, fission or fusion. Nuclear waste recycled or glassified and buried.\nElectrical Food Chain:\nPhotosynthesis is just a way to knock electrons off atoms. In principle, it can be done with electricity alone. There's active research on this. Probably soon we'll have microbes that can produce sugar, fats etc from a current.\nMore simply synthesize high energy compounds and let microbes eat them.\nLastly, convert electricity to light, put plants under lights, stack as high as needed.\nRegardless of method, food is produced in highly compact areas in quantity year round.\nCarbon cycle remains closed.\nRaw Materials No real changes, everything recycled simply because there is no place to put waste. Mines and the like are just in the basement.\nHeat\nThe real problem with a planetary city is heat. Urban areas are already heat islands, always hotter than the surrounding natural terrain. Cover the entire planet and you'd heat the entire planet. Might actually cover the entire top in reflectors because really you don't need solar energy (solar panels are thousands of times less dense than nuclear power and they'd generate more waste heat per kilowatt.)\nPresumably the planet starts as a terrestrial planet and has seas. Seas are the major heat conveyers on earth. They are powered by solar evaporation which changes density causes changes in density of seawater at top causing it to fall. If you build over the ocean you will stop the heat conveyers and the poles and the equator will have radically different temperatures which will produce storms.", "208" ], [ "Likely, they will dump some waste heat back into the ocean to mimic solar effects and keep the conveyer going.\nThe real problem will be radiate enough heat into space. There is a phenomena called \"heat pollution\" that will occur when just the heat dumped into the atmosphere by technology starts to alter climate and drive storms.\nMost likely a civilization advanced enough to build a planet city could figure out alternative radiators for the planet e.g. radiating lasers, magnetic radiators or just a bunch space elevator like structures that were just radiators carried huge amounts of heat from the ground to space.\nEconomics: To my mind, the major technical road block to a planetary city would be one of what pragmatic or economic forces would drive that many people to pay the enormous price of cramming that many people together?\nPopulation will not grow as populations urbanize because children cost a great deal in urban areas and unlike under farming, produce no income until well into adulthood. Long before a planet gets paved over, population growth will be flat or even declining.\nDense urban cores, especially ones with skyscrapers, were justified by the need to cram lots of people close together so they could communicate with analog technology. Such dense cores are already technologically and economically obsolete, though not with out their lifestyle appeal for many.\nWe've long passed the stage where people had to be in New York to hit the big time. Major corporations are spread all over the world in urban areas big and small. It's as easy to send email around the world as in the same building.\nI think the most likely scenario might be a completely non-economic reason to cram hundreds of billions of people on a single planet.\n* A prison for a very large galactic civilization, perhaps locking up entire societies for some reason.\n* A refuge of some kind, everyone is there because it's the only place to survive. It could be a hiding place or a fortress. If the latter they would be like people fleeing the barbarians to hide in the castle.\n* Planet city, but mostly empty. For whatever reason, a lot more city got built than needed. Runaway autonomous construction robots is a scenario I've seen once or twice. In that scenario, the city becomes the geography with 99% of it empty but maintained the robots. Spooky.", "99" ], [ "Shear stress in Interstellar docking scene\nThe movie Interstellar has a scene where a huge spaceship (64 meter diameter ring) called Endurance is spinning out of control after an explosion. The protagonist slows its angular velocity down by docking his smaller craft (Ranger) to Endurance and using Ranger's retro thrusters for about 30 seconds until their (Ranger+Endurance) angular velocity is reduced to zero.\nThe first time I watched the scene, I couldn't stop thinking the docking mechanism would have to be massively strong to resist the shear stress caused by the torque applied to Endurance.\nI did some back of the envelope calculations to estimate the shear stress it would have to withstand.\n$$ \\omega = \\frac{2\\pi}{T} $$\n$$ \\alpha = -\\frac{\\omega}{\\Delta{t}} $$\n$$ I = MR^2 $$\n$$ \\mathcal{T} = I\\alpha = -\\frac{2{\\pi}MR^{2}}{T\\Delta{t}} $$\nWhere:\n$$ \\omega \\text{ is the angular velocity of the Endurance.}\\ \\alpha \\text{ is the angular acceleration required to stop the spin.}\\ I \\text{ is the moment of inertia of the Endurance approximating it to a ring.}\\ \\mathcal{T}\\text{ is the torque required to slow the Endurance down.} $$\nMy estimates follow: $$ T \\text{ is visually about 6 rpm, although TARS says 60 rpm. So } \\text{0.1 }s^{-1}.\\ \\Delta{t} \\text{ is about } 30 \\text{ s}.\\ M \\text{ is unknown.", "394" ], [ "I will use 445,000 kg to match the ISS mass.}\\ R \\text{ is 32 m, Endurance being 64-meter wide.} $$\nThe required torque would be $\\mathcal{T} = -954\\text{ MNm}$.\nThat is huge! And it should come from retro thrusters!\nSo I estimated the shear stress considering the docking mechanism to be a solid round shaft. It is a best case scenario, since it would have to be hollow to allow flow of people.\n$$ \\tau = \\frac{\\mathcal{T}r}{I_p} $$\nWhere:\n$$ \\tau \\text{ is the shear stress at distance }r\\text { from the center}\\ I_p \\text{ is the shaft polar moment of inertia.} $$\nFor a solid round shaft $I_p = \\pi{r}^4/2$. So if we consider a $\\text{2 m}$ diameter solid shaft, the maximum shear stress would be:\n$$ \\tau_{\\text{max}} = \\frac{2\\mathcal{T}}{\\pi{r}^3} $$\nAnd that would give $\\tau_{\\text{max}} = 607 \\text{ MPa}$.\nThis is above what most types of steel would withstand.\nDo my calculations make sense? Would that be possible in the real world anyhow?", "15" ] ]

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[ [ "Your reasoning is correct, but it seems to me that introducing the changing of $B's$ origin was kind or arbitrary. Usually, when we talk about Lorentz transformations, we do not talk about looking at individual lines from different frames in reference. Instead, a much easier way would be to actually make a change in the whole co-ordinate system itself.\nWhen you are talking about normal situations, when we consider only two co-moving people, the normal <PERSON> transformations hold, without actually needing spacetime diagrams. These are $$t' = \\frac{t - vx}{\\sqrt{1- v^2}}$$ $$ x' = \\frac{x - vt}{\\sqrt{1 - v^2}}$$ assuming we choose units with $c = 1$. These are the Lorentz transformations that you reasoned with only $A$ nd $b$ in account.\nNow, when we rather talk about more objects, like in the situation where one frame of reference has both $A$ and $C$, we prefer to use spacetime diagrams. But, then it is becomes less convenient to do the <PERSON> transformations on each and every worldline and measure values. So, we do a trick (which I will briefly describe here, and leave the nitty-gritties to you):\n1. Take any one object, for example $A$, and look how its worldline transforms in $B's$ frame. In your case, that was the first part of your derivation.\n2. Using the results you obtain create a matrix. By now, its seems apparent where this is going.\n3. Take the matrix you obtained and then apply it to the entire $A$ frame of reference (the co-ordinate system where $A$ and $C$ are located). This is standard linear algebra.\nThe new co-ordinate system that you get will contain every worldline ($A$ and $C$ in this case), from the reference frame of $B$. Yes, your reasoning was correct and works, but is not very convenient for frames with many objects.\nUpdate: I have been asked in the comments to touch upon the second update in the question. It is a way of deriving the $\\gamma(v)$ function.", "499" ], [ "But here is why that mathematically yields results but is not that correct.\n1. Anything involving faster than light travel is generally avoided due to the fact that special relativity tells us that nothing can travel faster than light. So, even in derivations and mathematics, it is preferable to avoid faster than light situation or reference frames.\n2. Time is not interchangeable. While spacetime diagrams are a very powerful way to model relativistic situations, they seem to imply that time and space can switch places by rotations. Physically, this is not possible: sure, you can make changes to the time and space axes, but you cannot switch them. (In very high gravity situations, like inside black holes, time and space can switch but then we need to take into account general relativity, which in this context is out of scope.)\nSo, though you get results, that is not actually the correct way to do it. Instead here are some clues to what you can do.\n1. Leverage symmetry: symmetry is a very important concept in physics, and in deriving the $\\gamma(v)$ there are two main symmetries which come into play. I won't just straightforwardly reveal them, instead for now, I will just say that they have to do with directions of velocities and the fact that all observers consider themselves at rest.\n2. Substitute: When I learned the derivation of $\\gamma(v)$, it used the fact that <PERSON> transformations work both ways: $A$ to $B$ or $B$ to $A$. So you substitute the values of one into another and work your way through it.\n3. Work your way through it: You inevitable have to do some very length but easy algebra. So instead of trying to find shortcuts, just go through it the ugly way, and the results you get will be simple and elegant.\nIf these sounded vague, it is because I don't want to give away the derivation steps completely. Rather, it is meant as an exercise to the reader to try and do this task.", "562" ], [ "The above answers seem to nicely summarize why charge is conserved in every frame of reference. I would like to take a different approach as to why that makes sense, and why the charge conservation law holds.\n1. Charge, current and conservation:\nThe most simplest way to state the conservation of charge is to say, $$\\frac{dQ}{dt} = 0$$\nThat the rate of change of charge in time is $0$, implying that the quantity of charge is a constant.\nBut, sometimes charge can decrease in a system. This does not violate the supreme principle, but rather states that charge can 'leak' or flow through an area, causing the charge in the system to decrease, and the charge outside to increase. So, the amount of charge in the entire universe is the same, but for smaller systems the above equation may not hold true.\nConsider a box with some charge inside of it. The charge can flow out through any of the faces of the box, thus decreasing the overall charge inside (it can also increase if the charges are instead entering the box). So, you need to take into account this flow of charges, called a current to make sure that the conservation law holds. The resulting mathematical form is:\n$$\\frac{d\\rho}{dt} + \\nabla . J^i = 0$$\nwhere the $\\rho$ represents the density of charge inside the box, and $J^i$ is the current vector, because current can flow through the $x$, $y$, and $z$ axes; so we use a vector to keep track of them all. What the above expression says is: the rate of change of charge in the box and the rate of change of current flowing in or out of it, is going to be conserved.\n2. Four vectors, dot products and Lorentz invariance:\nIn Relativity, we use something known as four-vectors, which are 4 dimensional vectors. Usual vectors have only three components: one corresponding to each dimension of space; in Relativity, we consider a fourth dimension: time.", "780" ], [ "So, vectors in Relativity have four components, one corresponding to time, and three to space. We denote these vectors by $$A^{\\mu}, \\mu = (0, 1, 2, 3)$$ where the $0$ index corresponds to the time component and the other three to the space components.\nNow, let's move on to Lorentz invariance. In Special relativity, whenever we want to consider events from a different reference frame, we use something known as Lorentz transformations. I am going to leave a few nice resources in the further reading below, but for now, that is enough information.\nIf a certain quantity does not change when the Lorentz transformation is applies to it, we say it is Lorentz invariant.\nSo, some of the things that are always Lorentz invariant are the dot product between two four-vectors. Again, for length purposes, I will leave a link to some resources below, but simply put, dot products between two vectors can be denoted as: $$Product_{dot} = A^\\mu B_\\mu$$\nThe only constraint is that the index of the four vectors should be the same and they should be repeated upstairs and downstairs. Expanding this expression, we get: $$A^{\\mu}B_{\\mu} = -(A^0 B_0) + (A^1 B_1) + (A^2 B_2) + (A^3 B_3)$$ which is a scalar and is Lorentz invariant. These scalars are called Lorentz scalars.\n3. Bringing it all together:\nIn Special Relativity, we denote the charge and current of a particle as a four vector $J^{\\mu}$. The time component is $\\rho$ and the space components are $J^i$. There is another four vector $\\partial_{\\mu}$ which is defined to be: $$\\partial_{\\mu} = \\left (\\frac{\\partial}{\\partial t}, \\frac{\\partial}{\\partial x}, \\frac{\\partial}{\\partial y}, \\frac{\\partial}{\\partial z}\\right)$$\nOkay. Now, particles have some properties, like mass and charge that do not change when you shift frames. Similarly for the conservation of charge, you can write it as $$\\partial_{\\mu}J^{\\mu} = 0$$ which is a dot product, so it is naturally a <PERSON> invariant.\n4. So, can charge vary for observers?\nI took an unconventional way of answering here, by first showing the true way of expressing the conservation of charge and then going through a long way to show why the law hold even when our frames change.", "418" ], [ "Relativity is a theory of frames of reference. The question says that $\\Delta t$ is the time measured between two events by two synchronized clocks in frame $S$. But now, here's the catch: $\\Delta t$ is actually the time between the two events as observed by $S$, as observed by $S'$.\nUsually, in SR, we try and compare the flow of time and the measure of lengths, with respect to another frame. So, the $\\Delta t$ in the equation above is what the person standing in $S'$ sees in his frame. Let me try and explain.\nSuppose you look at it from the perspective of $S'$, with $S$ travelling relative to $S'$ with velocity $v$. Let's give them both stopwatches. Now, let two events $A$ and $B$ happen in $S$. When $A$ happens, $s$ (the observers are denoted by small letters here) starts the stopwatch. When $B$ happens, he stops the stopwatch.", "562" ], [ "The time between them is $\\Delta t$, as we know from the question. Now, will the time between them, as seen by $s'$ be the same? No. The stopwatch will start and stop at a different time, so you get $\\Delta t'$.\nBut now, say $s'$ is trying to see how much time elapsed according to $s$. He will see that $$\\Delta t = \\frac{\\Delta t'}{\\sqrt{1 - \\beta^2}}$$\nThat's where we have to compare two observers instead of one, and think about how the clocks in two separate frames are synchronized.\nComing back to the question the OP asked, it does matter how clocks are 'ticking' in other frames, when you are comparing some quantity in your frame to the others. That's what the word 'relativity' means. How $S'$ behaves relative to $S$ or vice versa.\nWhen $S'$ tries to measure what $\\Delta t$ is going to be, of course he cares about how the clocks are synchronized in that frame. Because, he is trying to find out how much time has elapsed in the other frame.\n$\\Delta t$ in this context isn't the time that $s$ measures. Instead, it is the time that $s'$ sees has passed for $s$. And how does he 'see' how much time has passed for $s$? By finding out what time the clocks (or stopwatches) in $S$ are showing in between the two events (which includes measuring whether they are synchronized or not to get a better idea), and comparing those values with that of his own clocks.\nSo, that is why it matter to know what is going on in other frames. You may see a lot of bold and italics in this answer, and that is because this is a delicate concept, and you need to know what's going on exactly and not get caught up on the long sentences.", "562" ], [ "I will try my hand in simplicity...\nMomentum is the measure of motion.\nSo, it is a measure of how much stuff is moving, and how fast that stuff is moving.\nWhat we call mass at the very basic level is \"amount of stuff\". Very interestingly, more stuff is heavier (pulled more strongly by the Earth - gravitational mass) and harder to move around (change velocity - inertial mass). By some conspiracy of nature (which we think general relativity explains) these are the same to the best of our knowledge. So, more stuff is more stuff, and we call the answer to \"how much stuff\" the mass.\nThis all depends on experiment, you see. By experimenting, we have observed that two pieces of stuff moving at a certain speed (let us consider one dimension here, which is sufficient to understand what momentum is) can be exchanged for one piece of stuff (that is, half the mass) which was originally at rest moving double that speed, with the original two pieces of stuff having stopped. You have to arrange the collisions carefully, and avoid affecting the three pieces externally, but this can be done.\nSo, observation of colliding masses (which is essentially electromagnetic interaction, but let us not digress) with negligible external effects (like friction) you can arrive at the following conclusions:\n(1) The amount of stuff moving can change.\n(2) The speed of motion can change.\nSo that is not really a lot. But as it turns out, the product of stuff and speed summed together does not change. This can be confirmed by further experimentation - so we give it a name. Call it momentum. (We could have called it <PERSON>. Not convenient, but possible. A name is a name.)\nIn trying to describe how this quantity, which is conserved but can be exchanged, is actually exchanged, we introduce the concept of forces. A force is how momentum exchanges hands, so to speak. How much momentum is exchanged depends on how much force is applied and for how much time it is applied.", "343" ], [ "(This even holds relativistically, if you use the relatvisitic momentum.) If the force is internal, that is between two pieces of the system you are studying, one gains momentum while the other loses it -- and in the exact same amount. This is essentially <PERSON>'s third law. But, if you apply an external force (whose reaction force, that is, canceling pair is not within your system) the momentum of the system you are studying will change. You can always expand your system and include more stuff, and ultimately you will have a system whose momentum is conserved. Thus, as far as we believe, the momentum of the universe is fixed.\nAlthough not strictly part of the answer let me add the following:\nConservation of momentum is the coolest conservation law ever. It is always valid. Relativity? Yes (use the correct form). Quantum systems? Yes. Newtonian mechanics? Of course!\nEnergy is also very carefully conserved by nature, but it is a bit more subtle. When studying macroscopic objects, you need to track heat exchange and internal energy. Also, potential energy is sometimes easy to miss. Momentum? Very nice and simple.\n... well, sometimes in charged particle collision, you get a radiated photon which you need to be careful about (it carries some momentum away). But that is significant when things are relativistic. Oh well.", "343" ], [ "In General Relativity, which is our current description of gravity, changes in the gravity field is mediated by gravitational waves.\n1. What are gravitational waves:\nIf you have any medium, and you add some energy to it, it starts to oscillate or wiggle. In other words, there is sort of a disturbance in the medium. This is true for air, water and even massless fields like electromagnetic fields. These disturbances are waves.\nIn GR, gravity is described as a property of the geometry of space and time itself. Any matter or energy can change the geometry of spacetime, and this is what other objects experience as the 'gravity' of the first one.\nSpacetime is a medium in GR. It can ripple, it can be disturbed. Indeed, in situations where there is movement of energy, the spacetime around it can 'squish and squash', causing a wave of spacetime itself.\nNotice, I did not say a wave in spacetime, because the spacetime itself is waving. Space and time expand and contract. That is a gravitational wave.\n2.", "343" ], [ "What is the speed of gravitational waves:\nIf the spacetime itself is waving, then how do we define the speed of those waves?\nSimple put, we take two objects separated by a long distance and interacting through gravity. Now, if we slightly change the position of the first one, the second one will not immediately change its motion. Instead, there will be a time gap. The distance between the two objects (before and after the change doesn't matter as we only slightly changed it; also the corresponding change in movement is small).\nNow the large distance between the two objects divided by the small time gap gives us how fast gravity can propagate (through gravity waves), in other words, the speed of gravity,. That is how we define it: in terms of the distance between objects and the time gap between movement of a large object and corresponding effect on the smaller object.\n3. Trivia: What does that come out to be?\nAs it turns out the speed of light $c$. This is because of the fact that waves can be thought to have 'mass', which is basically the mass of the medium (remember that the wave is nothing but a disturbance in the medium; so the mass of the wave is the mass of the medium, in a simplistic sense).\nNow, electromagnetic fields have no mass and the wave in the fields is light. Special Relativity tells us that anything without mass travel at the speed of light, a constant $c$.\nSpace-time itself is massless too; it may contain mass in it, but that does not mean that it itself is massive too. Okay. So a wave in spacetime, is massless, and by the laws of physics, can only travel at the speed of light.\nTa-da!", "343" ], [ "There is a general reasoning that takes into account your chemical reaction and any other time dependent process. The reason for this is that no matter the reaction, it is always going to take the same amount of time in its own proper time. Gravitational effects would be negligible for the reaction itself, as it is when one considers atoms and atomic scaled objects.\nFirst notice that if one were to construct your setup even for inertial observers in <PERSON> spacetime at rest with respect to each other and separated by a distance $L$ with a reaction that takes a time $T$, the setup would have to be changed a bit so the computation can be done. For example, one could assume there are two synchronized clocks in each of the reference frames that would perform the reaction and that they start the reaction at $t=0$. Then, the time so that the light ray emitted at $T/2$ from wither source to reach the other would be simply $T/2+L$.", "562" ], [ "We would see a delay for the communication, which would be associated to the time light takes to travel between them.\nIn general spacetimes we would have to keep track of two things: The time the event takes to occur and the time the light rays take to travel between the observers.\nTo solve the problem assume the proper time so that the reaction takes place is $T$. If one observer is at the radial coordinate $r_1$ and the other one at $r_2$ and both are static in Schwarzschild spacetime, then the coordinate time $t$ that will represent the times the reaction takes to occur will be given by their proper times, $$T_1=\\frac{T}{f(r_1)},$$ $$T_2=\\frac{T}{f(r_2)},$$ where $$f(r)=1-\\frac{2M}{r}.$$\nTo solve the problem I will assume the reactions start at the same coordinate time, which could be achieved by sending a light ray to both from a point in between (synchronizing their clocks).\nNow we need to compute the proper time it takes for one of the observers to receive a light ray emitted by the other. The coordinate time parametrization of the light ray can be obtained via\n$$0 = ds^2 = - f(r) dt^2 + \\frac{dr^2}{f(r)}\\Rightarrow \\frac{dt}{dr} = \\frac{1}{f(r)} \\Rightarrow \\Delta t = r_2 - r_1 + 2M log\\left(\\frac{r_2-2M}{r_1 - 2M}\\right).$$\nThus, the total $coordinate$ time it takes for a light ray originating from $r_1$ to reach $r_2$ is given above. In terms of coordinate time, we then have the total time to reach $r_2$ given by $\\Delta t + T_1/2 $. Subtracting half the time it takes for the reaction at $2$ to take place we obtain the final answer in coordinate time:\n$$\\Delta t + \\frac{T_1}{2}-\\frac{T_2}{2} = r_2 - r_1 + 2M log\\left(\\frac{r_2-2M}{r_1 - 2M} \\right)+ \\frac{T}{2}\\left(\\frac{1}{1-\\frac{2M}{r_1}} - \\frac{1}{1-\\frac{2M}{r_2}}\\right).$$\nTo obtain the time in the reference frame of $2$, we simply multiply the result above by the redshift factor $$\\frac{1}{\\sqrt{1-\\frac{2M}{r_2}}}$$.\nI really enjoyed doing this computation :)", "272" ], [ "I think I have solved the problem after thinking about it.\nBasically, I forgot the mathematical formalism for a moment and thought about it physically. We want to know the general velocity and position of a body that is moving at constant acceleration. Therefore, all we need is one moment in time for which we know the position and velocity, then we can use the constant acceleration to get other times. In other words, we know $v(t_0)$, so we just do $v(t_0)+at$ for times more than $t_0$, and $v(t_0)-at$ for times less than $t_0$. This is without using any \"mathematics\", since we know that each second, the velocity increases by $a$ since it is constant acceleration.\nNow let's see how this compares with the integral formalism. As it turns out, $t_0$ is not an initial time at all, it is only an arbitrary time, as it clear from the intuitive physical explanation above. It is only when we come to the mathematics that it all of a sudden becomes an \"initial\" time. Do you know why? Because in the mathematical formalism, when we work out the area under the a-t graph, we have to choose an \"initial\" time on the graph from which we work out the area.", "499" ], [ "It couldn't be otherwise, since area is 2-D and we have to start somewhere, ie $\\int_{t_0}^t$. If there was some magical mathematical way we could avoid starting somewhere, and invent a notation where we don't appear to \"start\" at $t_0$, say $\\zeta(t_0)$ (this isn't like $\\int_{t_0}^t$ which has the illusion of \"starting\" at $t_0$ and moving to $t$), then it would be as clear as the physical explanation above. (However, I guess we can rest contented with the fact that $\\int_{t_0}^t = -\\int _t^{t_0}$, so that it does have symmetry after all, and does not have to have an illusion of starting at $t_0$). Unfortunately, this is not the case. So the mathematical formalism makes it look like $t_0$ is an \"initial\" time. It is not: it is simply an arbitrary time for which we know v and x.\nSo it isn't as simple as I thought at first. The fact that authors call it \"initial\" and \"starting\" time is due to the mathematics, in particular, how it appears on the graph. It has nothing to do with the physics.", "499" ], [ "This is a question everyone asks at first because it intuitively seems like a contradiction. However, it is not.\nConceptual Examples\nI think you are not far off but perhaps the third law is the one tripping you up, not the 1st... But anyway, here are some conceptual examples, which might help...\nExample 1.\nConsider the particle in the frame for a moment. Is it moving or is it still? Well, we know that:\n* A particle moving at velocity $v=0$ (in its own inertial frame) is at constant speed and constant acceleration because $$\\frac{d v}{dt}=a$$\nSo if $v=0$ then it follows that $a=0$.\nHowever, it is vital you make sure not to confuse this with a case when $a=0$, because in that case v could be $v=0$. Velocity might not be zero at all, the thing about constant acceleration is there is no change in speed because the individual forces acting on bodies in the system sum to zero.\n$$F_{net}=F_1+F_2+...+F_n$$\nExample 2.\n* A particle moving at velocity $v\\approx c \\approx 3\\times 10^{8}\\mathrm{ms^{-1}}$ (in its own inertial frame) is moving at constant acceleration, but it is definately moving and very, fast too! Though, it is likely to have negligible mass at that speed, don't worry about that for now.", "766" ], [ "I am just trying to help you stop thinking of velocity and acceleration interchangeably (if that has been the source of the confusion)\nRemember, we are talking about simple models involving conservation. So just because there is a reaction force in the system, that does not mean nothing in the system can move, but it does mean that net force, in the inertial frame of the system, $F_{net}=0$ which is not the same as velocity $v=0$ at all...\nThis:\n$$\\frac{d p}{dt}=m\\frac{d v}{dt}$$\nTry to do some momentum conservation problems to help you get your head around the idea and recognise $a$, $v$, $x$ graphs of acceleration, velocity and displacement with respect to time, respectively.\nWhat it means mathematically is that mass by the derivative of velocity is zero - or in other words: The change in momentum of the system is zero, which is different because the change in momentum is given by:\n$$\\frac{d p}{dt}=m\\frac{d v}{dt}$$\nExample 3\nImagine you are still for a moment and you find yourself in the path of a car driving towards you in a straight line at a constant speed of $20ms^{-1}$ you for some reason prefer to stay stationary (a pretty extreme hypothesis test!).\nA collision happens between you and the car and you might expect to change your speed (from rest) pretty fast, and in the opposite direction on impact. You will do this at a ratio proportional to your initial speed and mass plus the speed and mass of the car equal to the final speed of you and the car (and once you get that. the next stage is getting familiar with varying mass problems - yay rocket science!)\n$$m_1 u_1 + m_2 u_2=m_1 v_1 + m_2 v_2$$\nMomentum is conserved: Alrthough you might be worse off than the car, this is so because the car has a larger mass\ni.e. you go flying in one direction, because you are subject to the force of the car and the car is dented because of you but the net speed and mass of both of you combined is the same after the collision as it was beforehand\nmomentum $\\frac{d p}{dt}=ma$:\n$$\\frac{d p}{dt}=m\\frac{d v}{dt}=ma=F_{net}$$\nThe first law states that a body will move at constant speed and direction unless an external force causes the body to change speed and/or direction.\nAn external force is not (by definition) in the inertial frame of a body which is moving at constant speed (inside its own inertial frame as it goes...)\nIncidentally, this idea of reference frames was first conceived by <PERSON>, when he came up with this notion of invariance.", "512" ] ]

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[ [ "Space Chicken Spaceship Chicken Coop\nIntroduction: Space Chicken Spaceship Chicken Coop\n(Opening song; Rocky Horror Picture Show, first stanza) (open this link in another tab and sing along!)\n<PERSON> was ill the day the earth stood still\nBut he told us where we stand\nAnd <PERSON> was there in silver underwear\n<PERSON> was the invisible man\nThen something went wrong for <PERSON> and <PERSON>\nThey got caught in a celluloid jam\nThen at a deadly pace they came from outer space\nAnd this is how the story began:\nSpace Chickens in Space! 2\nIn the beginning three chickens accidently enroll in a diplomacy school where they had to face unthinkable challenges of technology, school and sibling relationships in outer space. All goes well for 26 episodes, and then things go from bad to worse when our intrepid Space Chickens pick up an intergalactic hitchhiker! Without considering the improper weight-and-balance distribution that their newest cast member would cause to their spaceship, they are forced to crash-land on planet Earth (in my backyard) and were subsequently dropped from syndication! But their problems didn’t end there.\nOnce they were exposed to our sun they did not become super beings (with strange and awesome powers), nor did they keep their intelligence; instead they reverted back to normal chickens [albeit extremely friendly ones at that]!\nThis is where I come in; I needed to get them back into thinking (and acting) like the Space Chickens they are, so I built them a new chicken coop to remind them of where they come from. But being the poor chicken farmer I am, I had to build it entirely broken, discarded, obsolete or used material. (I also needed to build a new chicken coop because the one that they are currently roosting in was built in a hurry and designed to be temporary at best.)\nDisclaimer: I am a packrat for all defunct gadgets, broken appliances, knobs, covers, antenna and removable paraphernalia [from all things my wife wants me to pitch]. For me, this project was a no-brainer.\nThe following is a pictorial chronology of my efforts to return these wayward space travelers back from whence they came (or at least make them feel at home).\n1. Science Fiction – Double Feature by <PERSON>2. Animated television series created by <PERSON> and <PERSON>\nSupplies\nI didn't need to buy any of the components for this spaceship; I had most of this stuff stashed away in one bin or another. Some of them are just cool packaging trays, some are just extra stuff from things I bought, some I fished out of friend's garbage and others are actual defective/discarded hardware that I made in my previous professional life. I did have to buy a few things however...\nBill of new material used:\n3 Piano hinges\n3 Strap hinges\n1 Box of screws; 100 count\n2 Cans of grey spray paint\nStep 1: Find the Right Fuselage.\nI knew that I couldn’t build a standard coop and hope to fool the chickens (unless of course I fashioned a TARDIS) so I started looking for a suitable spaceship vestibule.", "820" ], [ "A fellow farmer had a busted 3,000 liter water tank. (The foot had a nasty crack and would no longer hold water). It was a little bigger than I wanted (or needed) but beggars can’t be choosers so I took it off his hands. Besides, he was only too happy to see me cart it away!\nI used a cordless circular saw and cut it half along the seem. It was too big to bring home in one piece so I had to bring it home one half at a time.\nStep 2: Construct the Interior.\nI had about a ½ dozen rough-cut 8’ 1x6’s left over from pouring concrete to make the interior framework from (since I had used them as forms they weren’t good for much else). Using about 3 of them I built a support frame [that nested in the bottom half of the tank] and another 4 of them to fashion a removable tray. I used a couple spare feet of chicken wire to line the bottom of the tray. Then I used a couple of metal framing brackets as temporary tabs to line up the top and bottom.\nStep 3: Reassembly.\nAfter I got the top back on the base I used a piano hinge to line up, and secure the top to the base. I then relocated the metal tabs from the inside to the outside. This would make it a rigid structure and easier to move around.", "787" ], [ "Hammock Shed (aka Outdoor Storage Box)\nIntroduction: Hammock Shed (aka Outdoor Storage Box)\nI wove my own hammock a few years ago and since then I've been very paranoid about leaving it out in the elements. If you put that kind of work into something you get a little protective. If I see rain clouds on the horizon I unhook the hammock and drag it back into the garage. I can count on both hands the number of times I've left it out overnight. In the winter it slumbers in a large plastic bag in my attic. It's excessive. It's compulsive. It's obsessive. It has to stop. And here's the solution - a hammock shed.\nStep 1: Alternate Uses\nWhat brings more pleasure than swinging lightly in a shaded summer breeze? Not much. Maybe a small basketball (as see in the picture). But this need not be just a container for a hammock. Think of things you constantly bring in and out of your house, garage, shed and into your yard. Any of these things could fit into a custom made storage box and fitted to a tree in your yard (or to a 4x4 post set in concrete wherever you like). The two big uses for this kind of container that I can think of are for yard games and garden tools. If you and your family have one of those badmiton/volley ball sets, croquet sets, horsehoe sets or whatever then this might be a great storage solution for you. If you enjoy gardening then a well placed box with your shovels, hoes, and miscellany might be a time and energy saver. Could also be used to hold garden hoses, drip irrigation hoses, loads and loads of things.\nStep 2: The Needed\n* 4 - 1\" x 10\" x 6ft boards\n* 1 scrap piece of 1\" x 12\" board\n* Outdoor screws - here I used stainless steel\n* hinges\n* weather stripping gasket\n* lock latch\n* A drill\n* A compound miter saw helps greatly, but a hand saw would work nicely.\n* Chisels\n* Wood glue\n* Shop vac or broom for the horrid mess this makes\nStep 3: The Wood\nI decided to put a sloped roof on this box. I settled on a 15 degree slope. I cut the two sides accordingly and gave the back piece an angled cut to match as well.", "644" ], [ "While I had the saw set to this angle I cut the 1\"x12\" scrap piece to be the roof board.\nStep 4: Glue It, Screw It\nDrill the holes that the screws will go in so that you won't risk cracking the wood. Apply a thick coat of glue before screwing them together. I used one screw per foot.\nStep 5: The Bottom, the Top\nI measured the bottom and cut the wood to fit, then I drilled, glued, and screwed it. With the top I used the 1\"x12\" scrap piece to give a little overhang. It too was drilled, glued, and screwed.\nStep 6: Hinges\nUpon reflection I think I should have used 3 hinges. I may add one eventually if the wood decides it wants to warp. Cutting the wood away for hinges is called mortising. There are a number of machines and \"jigs\" out there for routers and other tools. I have none of those things and opted for a chisel and hammer. I marked the length of the hinge and then the depth and slowly worked the wood away. The hinges were then screwed on (the holes were drilled first; always pre-drill). You'll have to do this on both the door and the box.\nOkay, you don't actually have to mortise for the hinges, but it will make less of a gap and hence a tighter seal if you're interested in that.\nStep 7: Stripping\nThere are a number of ways you can attach this vinyl weather stripping. I chose to go with a staple gun. If I'd have had a pneumatic stapler I'd have gone with that. I didn't bother putting glue or silicone beneath the stripping, but you certainly could do this. I stapled about every 2 to three inches.\nStep 8: Latch and Hole\nI drilled and screwed on the latch and then drilled a hole in the back of the box for the large lag bolt hook that I use to hold the hammock chain.\nStep 9: Mount and Finish\nHere it is mounted to the tree and the hammock installed. I'll probably post another picture once I paint it.\nYou could make these out of cedar. The cost will be higher, but you could probably get away with not putting any kind of finish on it at all. Plus whatever you put inside of it will smell like cedar. And it'll keep some bugs away.", "56" ], [ "Fuel Pellet Adapter for a Wood-burning Fireplace (or Stove)\nIntroduction: Fuel Pellet Adapter for a Wood-burning Fireplace (or Stove)\nWelcome to another kick-ass Instructable from Disc Dog!\nI have a wood-burning fireplace/stove in our house. By and large it supplies most of the heat for the house during during the evening in the colder months; it's a small house (about 850 sqft). When I bought the stove (about 4 years back) Pellet Stoves were coming out in full force, but [having an abundance of free wood lying about] I didn't savor the idea of having to buy a $5 bag of wood pellets every day just to have a fireplace. (MOst pellet stoves burn about 3/4 to a bag a day) True, they are efficient and, depending on where you live, cheaper than running most heating systems but still, it's hard to compete with 'free'.\nInevitably there would come a long-enough winter to exhaust my chopped, dried wood supply but I figured that we spend enough time outdoors during the day that I wouldn't see that long, indoor period for a number of years.\nThen came Covid...and the quarantine that kept us indoors aaallll daaaaay looooong, months on end. This year I ran out of wood before we ran out of cold, wet days. Time to think outside the box...\n(The other issue I have with pellet stoves is that they need electricity to run! A wood burning stove that needs electricity to work doesn't do you a lot of good during a power outage, especially when you need heat the most!)\nI have a friend who welded up a cage [from expanded metal] to fit in his fireplace. (He has an open fireplace) He would just dump a 40 lb. bag of wood pellets on evenings when he wanted a fire, light it off and enjoy a nice fire. It was expensive [but as he put it] he \"didn't have the hassle of cutting, storing, burning and dealing with the mess of burning cut wood in his fireplace\". I did a little research and found that you can buy these wood baskets on line for anywhere from $20-$60, and that some of them are modified to deal with just wood pellets. I decided I could build a better, more efficient adapter that would only burn about 10 lbs.", "842" ], [ "of pellets every 4 hours and STILL put put out a good, steady amount of flame (and heat) to warm the house up very nicely.\nStep 1: What You Need and What It Costs; <$8 and <2 Hours\nYou'll need a section of 'machine netting' (rabbit-hutch screen) big enough to fold up and fit inside your fireplace/stove. Your screen section should be made of steel, as stout as you can get, and should have very small holes (most rabbit-hutch screen has 1/4\" holes, and that works fine). If you can find the smaller, 3/16\" or 1/8\" netting so much the better.\nMeasure your fireplace/stove floor. Get a piece of netting that is 1-1/2 times longer and wider than the floor of the fireplace. My wood-burner is very small, and only measures about 30 cm x 20 cm [on the inside], so I bought a piece of 60 cm wide netting. I needed about 90 cm for the box so I had the store cut me a piece about 1 meter (100 cm) long.\n(I originally use a piece of steel sheet-rock corner bead but it didn't last long because I let the fire get too hot. Read more about that on the last step) Use heavy gage steel construction angle or shelving angle [as shown] to make the base of the pellet box. (Do not use plastic or aluminum). You will need to use a right-angle grinder with a metal cutting wheel to cut up your angle for the base\nYou'll also need some thin, pliable steel wire [typically used in construction work for temporarily tying up or securing things together].\nThat's it; less than $8 worth of supplies.\nYou'll need a measure, a felt-tip pen (for marking the netting wit) and a couple of pliers to weave, twist, bend and/or cut the wire with. Make sure you have a good pair of diagonal cutters (pictured above) to cut the netting with.\nIt took me a bit less than an hour to put the first version together and then another 30 minutes to modify it. All-in-all, It should take you less that 2 hours to put one together. It took me another hour to modify it with the better base.", "56" ], [ "Bending Wood / MDF\nIntroduction: Bending Wood / MDF\n“Where the curve starts a proper earning ends” my grandfather, a carpenter by trade, used to say.\nWell, after some experience gained I totally agree with him. Compared to angular joints curvy and bendy shapes made of wood take an infinite time longer to make. The best way to bend wood and medium-density fibreboard is by the use of steam. Since I don’t have a steam chamber I was looking for an easier way for an aspiring project, the make of a flowerbed for my balcony.\nThis Instructable shows a technique almost forgotten – shaping wood and medium-density fibreboard by watering it and the use of ammonia.\nSupplies\nThose are the things you need:\n* several clamps\n* Ammonia (I used a 10% solution)\n* spray can\n* tension belt\n* wood glue\nPLEASE NOTE: ammonia solution, or ammonium hydroxide, to be precisely, is an extremely hazardous liquid. It was widely used as a household cleaner until a couple of decades ago. The stench is almost unbearable.\nAlways wear goggles, gloves and a mask and apply it only on the outside!\nStep 1: Soaking the Wood / MDF\nThe principal idea is to bend small layers of wood and / or fibreboard, let them dry and then glue them together.\nFirst I sprayed the cut pieces with a 10% ammonia solution on both sides. I did this twice and let everything dry for a day.\nThen I watered the pieces.", "254" ], [ "The strong stench of the ammonia is nearly gone, I did this in my shower cabinet.\nStep 2: Bending It in Shape\nAfter the soaking I bent the pieces around the shape they should take and fixed everything with clamps.\nI left it that way for a couple of hours, then took it off and fixed it by the use of a tension belt. This is for letting the material dry off, also for keeping the shape (it would otherwise go back to almost normal).\nStep 3: Glueing Everything Together\nA day later you can start glueing everything together. Take wood glue and coat the entire contact area. Again put it around the shape or a pattern and press it as strong as possible together. Let it rest for 24h and take it off.\nSometimes some smaller spots on the edge between the layers didn’t properly stick together. I inserted wood glue into the gaps and pressed it again with a clamp.\nStep 4: Finishing\nI made the bent part of the flowerbed out of two layers of MDF, about 8 mm thick, and a thin layer of wood with a thickness of about 2 mm. The latter was for the visible surface, it shall match with the other parts of the construction.\nIMPORTANT: Since it is almost impossible to measure the proper length of a curve before, make sure all the pieces are a bit oversized and do the cutting later in place.", "556" ], [ "RavenClawed Wand Stand – Luna Lovegood Style\nIntroduction: RavenClawed Wand Stand – <PERSON> Style\nMy whole family is a bunch of dorks.\nI am dorky about old medieval/viking stuff, my wife is a big <PERSON> dork and we both are dorky for Star Wars. It’s probably a good thing my boys are homeschooled cause they are dorky about all of these things by now.\nIt was our 11th anniversary this year and since we are lucky enough to have whatever we need, we enjoy exchanging goofy gifts. (see my Falconry Glove from 2020)\nThe 11th year is Steel, one of my favorite mediums. So, I was excited.\nWe took an unexpected trip to Disney this year and my wife indulged her inner (and outer) dork by procuring a wand from Olivanders. She was chosen by a lovely little wand, slender and perhaps even “swishy”. The end is shaped like a tulip. It was Luna Lovegoods.\nIt is, dare I say it…fitting.\nWhen we got home she stated she clearly needed a stand on which she could show off her wand, otherwise it would live in a box and that was apparently unacceptable.\nSo off my mind went.\nSupplies\nScrap mild steel bar\nOld piece of firewood\nMetal files\nMetal cutting bandsaw\nSandpaper\nCold Blue\nQ-tips\nRubbing alcohol\nButcher block oil/wax\nEpoxy\nStep 1: Symbology\nPerhaps the word I am looking for is symbolism… ssssymbolism.\nHarry Potter is full of it and I needed to make the stand reflect both my wife and her house of Ravenclaw.\nI decided that a pair of bird claws holding up the wand would be pretty sweet, if one of the more complex choices. But after all, what are anniversaries for if not going the extra mile – plus I may have forgotten one or two so I really try now.\nANYHOW, I searched for vector files that look like something I could recreate in steel and came upon a couple that were not overly complex and could be modified to fit my needs.\nI “photoshopped” them (technically I guess I “paint.netted” them but that sounds weird) and removed a few claws/details since I already had ambitious goals and simplifying a bit did not hurt.", "348" ], [ "(See the above for before and after drawings)\nI took them, printed them out, made sure I didn’t leave a copy on the printer for my wife to find and grill me about and glued the claws to a piece of scrap mild steel I had.\nStep 2: How Do You Eat an Elephant\nOne bite at a time.\nLuckily, I have a decent metal cutting bandsaw. Being so small the claws were pretty trying to cut out cleanly and it took some time but little bit by little bit I got them into roughly claw shapes.\nStep 3: Files, So Many Files\nIf band sawing was time consuming it was nothing compared to using hand files.\nGood lord did this take some time.\nIt was much quieter though and it helped me work on my patience... which I feel I could use more of.\nI suggest a good assortment of files is a worthy investment for anyone who likes to make things from metal. I used primarily a wide flat one, a round one, a smaller square one, and some little needle files, each had the area it worked the best in and it took some trial and error.\nThe bad thing about files is they take a while to cut into steel.\nThe good part is you can’t instantly fubar a project like you can with power tools. And I have fubar’d a lot of stuff.\nFubar’d… Fubared? Fubarred?\nSomeone help me. Is there a proper past tense of FUBAR.\nStep 4: Doot Doot Doot Doot Do Do Do Doo Doo COLD BLUEY!\nSo after getting to final shape and really working the detail to the point I found acceptable I decided to use some cold blue I had leftover from something to really make those claws POP.\nI prepped the claws and cold blued all except the talons which I polished up extra bright. I thought it looked pretty snazzy.\nStep 5: All Good Things Need a Solid Base\nI thought about it a lot and decided that the base needed to be 2 things to go with my theme.\n1.) imperfect. For some reason wizards can’t figure out a Plum bob or level so nothing they have is square\n2.) natural material and <PERSON> approved.", "177" ], [ "Big Stylish Storage Over Stairs\nIntroduction: Big Stylish Storage Over Stairs\nOur house used to have a large chunk of wasted space above the stairs from the first floor to the second. It was empty all the way to the second floor ceiling. I decided to build in storage shelves and giant drawers for bedding and bathroom supplies. It turned out to be a really great addition.\nStep 1: Mock Up the New Ceiling Height Above Stairs\nMock up the new ceiling height above stairs to get a feel for how high it needs to be. I put up some light-weight materials to play with the height and live with it for a few days to see if it would bother anyone.\nStep 2: Mark Where New Storage Will Be\nI used black tape to mark the wall.\nStep 3: Remove Plaster and Lath Where New Storage Will Be\nThis is always messy. Protect the floors with drop cloths to collect the heavy debris. I built a temporary platform over the stairs to catch the plaster when I knocked it out from above. Then I hauled it to the dump in IKEA shopping bags which are perfect for the job.\nStep 4: Frame in New Storage\nI designed the spacing of the shelves to fit with the big translucent storage tubs we use for out of season clothes and other crap. The supports for the shelves and drawers are screwed to the wall with drywall screws.\nStep 5: Add the Shelves\nI had a supply of mdf shelves (9” wide x 4’) that I used for the shelves. Plywood would probably be better and lighter.\nStep 6: Frame in for Giant Drawers\nI created some drawer glides out of wood and 2” rubber wheels and some ball bearings.\nStep 7: Build Giant Box Drawers\nI first built the frame pieces for the drawers and clamped them together while fitting them into the space. Then I glued and nailed ¼” plywood to the frames to make the boxes. They are very light for their size.", "47" ], [ "Light duty as well. We don’t put heavy things in them. Blankets and pillows, etc...\nStep 8: Build the Shelf Drawer\nBecause of its height the third shelf opens from the side instead of the top, and so is designed differently with shelves of its own. We keep bathroom supplies on them.\nStep 9: Build the Shoji Doors\nThese were fun to make. I ripped some clear pine boards into ¾”x ¾” strips and used half lap joints cut on the table saw. When the fit was right I glued Japanese mulberry shoji paper to the doors. After the glue was dry, I lightly misted the paper with water. This makes them dry nice and tight and smooth.\nStep 10: Build and Install Paper Ceiling Above Stairs\nFor the new ceiling above the stairs I wanted it to be removable in case I ever need to service the drawer glides. I made four big single frames and put specially folded paper on them. They hang invisibly from pins that slide into the wall framing. To fold the paper I devised a sort of break bender. Then I glued it to the frames.\nStep 11: Done!\nThis project goes a long way toward making an old house with limited storage much more usable. We love it!", "959" ], [ "Mobile Table Saw Stand With Storage Drawers and Folding Outfeed Table\nIntroduction: Mobile Table Saw Stand With Storage Drawers and Folding Outfeed Table\nThis was my table saw stand. (Please don’t laugh.) I got a great deal on my table saw when I bought it, but the optional portable stand available for it seemed flimsy and overpriced. I opted instead, to repurpose this old aquarium stand by adding a 2’x2’ sheet of plywood on top. It worked for a while. (Kind of)\nOvertime though, I realized, it wasn’t level, the footprint was a little too narrow, and the joints were getting wobbly from dragging in around. I decided it was time to build something better with more functionality. I needed something sturdy with increased storage, and an outfeed table. I needed it to be mobile, and easy to fold up and put away.", "47" ], [ "Lastly, with the price of wood these days, my goal was to build it using either scrap, or repurposed wood that I had on hand.\nSupplies\nI was fortunate enough to be able to scavenge the wood needed, but here is an approximate list of materials needed if you want to build this.\nDimensional Lumber:\n(12) 2\"x4\"x24\" (Cube Frame)\n(2) 2\"x2\"x10\" (Outfeed frame)\n(1) 2\"x2\"x24\" (Outfeed frame)\nPlywood: (Preferably 3/4\" sanded surface, 1/2\" will work, Pine board also works well for drawer components)\n(3) 24\"x24\" (Cube Top, Cube bottom, and Outfeed table)\n(2) 24\"x35\" (Side panels)\n(1) 25\"x25\" (Rear panel)\n(2) 2\"x10\" (Outfeed frame cover)\n(1) 2\"x24\" (Outfeed frame cover)\n(4) 7\"x20\" (Drawer Sides)\n(4) 7\"x18.5\" (Drawer front and rear)\n(2) 7\"x24\" (Drawer Facades)\n(2) 18.5\"x18.5\" (Drawer bottoms)\nMinwax Wipe-On Poly Clear Satin Oil-Based Polyurethane (1-Pint) in the Sealers department at Lowes.com\nBlum 18-in Drawer Slide in the Drawer Slides department at Lowes.com\nPower Pro #10 x 3-in Bronze Epoxy Flat Exterior Wood Screws in the Wood Screws department at Lowes.com\nPower Pro One #8 x 1-in Bronze Epoxy Flat Exterior Multi-Material Screws in the Wood Screws department at Lowes.com\nAmazon.com: Anwenk Leveling Feet Heavy Duty Furniture Levelers Adjustable Table Leg Leveler w/Lock Nuts for Furniture,Table, Cabinets, Workbench,Shelving Units and More : Tools & Home Improvement\nSPACEKEEPER Workbench Casters kit 660 Lbs - 4 Heavy Duty Retractable Caster Designed for Workbenches Machinery & Tables: Amazon.com: Industrial & Scientific\nAmazon.com: 8\" Folding Shelf Brackets, Heavy Duty Stainless Steel Collapsible Bracket Wall Mounted DIY Foldable Brackets for Table Desk Workbench, Max Load 300 lb : Tools & Home Improvement\nTitebond Yellow Interior/Exterior Wood Adhesive (Actual Net Contents: 16-fl oz) in the Wood Adhesive department at Lowes.com\nStep 1: ​Build the Frame.\nI cut 12 pieces of 2”x4”x24”. I assembled a 24”cube frame. I built the tops and bottoms first, with the sides inset by 1 1/2” to allow the legs to sit at the outer edges of the cube. I added 2’x2’ plywood for the top and bottom.\nStep 2: Build the Enclosure\nI cut the side panels 35”x24” to allow support for the outfeed table, but cut out sections to leave the table saw accessible from the sides. With the sides in place, I built a frame in the rear using 2”x2” to support the outfeed table. Lastly, I cut plywood pieces to enclose the rear.\nStep 3: Mobility\nWith the frame and enclosure built, it was time to add mobility. I wanted it to be easy to move around, but also wanted the ability to lock it down firmly and level it on uneven terrain. I felt that just simple casters would be too wobbly.", "401" ], [ "Big Lazy Susan From Upcycled Cabinet Doors\nIntroduction: Big Lazy Susan From Upcycled Cabinet Doors\nI salvaged some solid maple cabinet doors a while back and decided to make an oversized Lazy Susan from two of them. It has 16 sides and is 25\" in diameter which is perfect for our dining table. Finished with Danish Oil.\nStep 1: Pick Out Doors\nI realized I would need two doors to make a slab big enough. I picked two that were not too much wider than 13 inches so I could conserve the resource. They are veneered maple over a core of laminated solid maple. They were pretty grungy looking, but I knew the wood inside would probably be nice.\nStep 2: Cut Down to 13” Width\nMy planer is 13\" wide, so I ripped the doors to that dimension on the table saw. I figured after trimming the diameter would be 25\".\nStep 3: Run Through the Planer\nI didn't like the antique color of the veneer so I planed it off. The laminated core looks nice.\nStep 4: Cut to Length\nI cut them on the table saw to the length of both door widths combined: 26\". They will make a nice square.\nStep 5: Glue Together\nI taped them together on the good side. Then folded on the tape to expose the edges. Added glue, and clamped with my two biggest clamps. I love those clamps. They're really old and cool. They were my grandpa's once.\nStep 6: Build a Faceting Jig\nMy plan was to cut off the corners of the square board.", "443" ], [ "But it being larger than my table saw, I had to do some figuring on how I could safely cut the corners while keeping the center a consistent distance away. I built a jig out of scrap that would allow me to bolt the center to a fixed point, and run in the miter slot of the table saw. I glued a runner for the miter slot to a piece of thin plywood, then measured from the blade to 12½\" out for the center hole.\nStep 7: Cut Off 4 Corners\nI glued a stop to the jig that kept the board from rotating during the cut.\nStep 8: Cut Off 8 Remaining Corners\nI moved the stop to work for the next 8 cuts.\nStep 9: Sand\nYuck. But it has to be done. Up to 320 grit.\nStep 10: Danish Oil\nApply liberally. Let it soak in for 15 minutes. Reapply. Wait 15 more, then wipe dry. It's great finish. It really brings out the wood grain.\nStep 11: Attach the Swivel Ring\nThese are awesome. There is no play in the bearings unlike the smaller more common ones you see. They can be expensive to buy, but I got this one from a yard sale for cheap. I drew a circle to line it up with the center, used an awl to mark the holes for the mounting screws, drilled pilot holes and then screwed them all together.\nStep 12: Test It Out\nAfter waiting over night for the finish to fully dry, I tested it out on the family to make Pan Bagnas. Yum.", "599" ] ]

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[ [ "Its survival depends mostly on what is available to it. While photosynthesis is an option for a source of biological energy if you have the required structures, CO2, and water, sustaining that system is going to take materials you may not have access to, such as certain minerals and compounds. However, given adequate knowledge and biomass, it wouldn't be beyond reasoning to reverse-engineer the systems that create all but the mineral components here on earth. Basically, re-create a biosphere to manufacture what you need. Either with separate minion-creatures contained within the shell, or as organ-like additions to the main creature. The thing is, this isn't as difficult as it initially seems. You don't need these organisms to survive competing in the wild, you can over-specialize and make them monstrously efficient, so long as you're willing to spoon-feed and protect them.", "258" ], [ "So-fungi/lichen/micro-organisms to break down rocks/dirt/excess biomass, flora to feed off of waste material from that and produce biologically usable energy & compounds, and fauna to recycle O2 back to CO2, anything more complicated than that can likely be hand-waved away for your general audience by sci-fi space-crab genetics.\nNow that we've established that with preparation, sustaining your brood is possible, we need to focus on long-term growth/development. If the moon in question was formed similarly to earth's moon (in that it's mostly material cast off by the planet during its formation process and later huge meteorite impacts) than you likely won't have much problem finding and re-purposing material to feed your growing brood, so long as the process is efficient enough that it's a net-gain, not a net-loss. Again, hand wave sci-fi space crab genetics, we're looking for stuff usable in-story, not to publish a scientific article. On the other hand, if the moon was formed by snagging passing meteors (such as Mar's Phobos and Deimos) the brood is going to have a much harder time finding the components they're used to breaking down for sustenance. But there's also the chance for serendipity to smile on them as well, and find a best-case scenario even better than what they're used to. That's assuming a barren moon, unlike Jupiter's Titian or Star War's Endor.\nTL;DR: we're already doing this on earth, rocks are broken down, minerals are consumed, the dead are recycled. You just need enough air, biomass, and overly-specialized organs/organisms in a concentrated space to self-perpetuate. Maybe checkout this fanfiction for some more ideas (be forewarned, the first chapter is a bit info-dumpy and tailored to those already somewhat familiar with Prototype's genetically self-modifying Blacklight)\nEdit: I've been seeing a bunch of references to the square-cube law and the like, but picture a mostly-hollow creature mixed with a hive?", "99" ], [ "The problem with how a creature could evolve to use light as a weapon is inherent to the issue presented - light does not make a very good weapon.\nEven with all the technology that we currently have, light has several very important disadvantages:\n* poor efficiency of generating mechanisms when approaching damage-dealing energy levels\n* very poor energy transfer\n* is easily deflected or absorbed by even the most rudimentary armor (shiny or dark and matte, temperature-resistant material)\n* needs to be focused and directed or it dissipates\n* susceptible to environmental disturbance (dust, fog etc. blocks it)\n* telegraphs attacker's position when used\nThus in a fight light is usually used as a distraction, lure, stunning mechanism or for communication.\nHowever, if we put all of these aside, how would that happen?\nLight may be used to blind the enemy, which is an attack in its own right. It could be used as a defense mechanism, assuming the predator usually looks at his target, a sudden flash of light might blind or stun him. However, biological mechanism used to generate sufficient amount of light might be tricky to design. You could consider plants that have an amount of flash powder in a pod-like or hard shelled compartments used to discourage foraging animals.\nA predator could be using external light sources, e.g.", "477" ], [ "biological lenses to focus sun's rays on it's prey. While this would be a cool way to cook its meal in the process, it is rather complicated and unnecessary.\nFor a laser-like damaging light, forget it. Biological sources don't generate nearly enough energy to be converted to a laser-like beam. Also, coherent light emitted by lasers requires much better quality of optics than anything known to biology.\nThe question behind a question is in fact the issue with inefficiency and difficulty employing this mode of attack. Unless you would design your world using very strange, pro-light anti-claw characteristics, a good old rip & tear will trump shine & burn anytime. And since you ask about such weaponry as an effect of evolution, which assumes light would be somehow preferable as a weapon to other ones, it simply wouldn't happen.", "477" ], [ "If a truly fuel-less launch mechanism existed, don't you think we'd be using it right now?\nEven air-breathing engines require fuel to heat and expand the air for thrust.\nOption 1:\nYour spacecraft deploys a space elevator down onto the planet. This'll probably require some preparation time. If your spacecraft has some manufacturing capability, it may harvest materials in asteroids and such to construct the cable and counter-balancing mass at +geostationary altitude (which could probably just be a raw, unprocessed asteroid tethered to the cable).\nThe spacecraft may aerobrake in the atmosphere if it is capable of doing so, but would need to ride the space elevator for perhaps a day or so to reach orbital altitude + velocity again.\nFor a fuel-less ride, the space elevator could have a matrix of solar panels at GEO for solar energy.\nOption 2:\nYour spacecraft deploys a rotating sky hook. Sky hooks are a type of momentum exchange tether. They are similar to space elevators but require much less cable & mass to build. They also require a large counter-balancing mass to exchange momentum with which, like the space elevator, could also be a captured asteroid.", "199" ], [ "Your spacecraft must simply be able to reach a target altitude & speed well below orbital and the tether carries you the rest of the way (no simple feat, but any competent spaceplane could make the rendezvous). If you don't care about the sky hook's orbit eventually decaying (possibly leaving you stranded if you can't reach it in time), you don't have to build any thrusters into it for orbital corrections (although there are a number of electrodynamic tethers that use the geomagnetics of planets for orbital corrections).\nThis is IMO the best option. The cable can be coiled-up and reused for later planetary excursions, and all one needs to do is find a large enough counter-mass (such as an asteroid) and to place the thing into the correct orbit.\nOption 3:\nYou leave your spacecraft in orbit and take a hypersonic airship down to the planet. This is JPAerospace's Airship-to-Orbit proposal for space launch & return missions. A mile-long, solar-powered hydrogen airship slowly decelerates to suborbital speeds over the course of a couple days, coming to rest several miles above sea level. (The airship is delicate due to mass constraints and must remain floating in the upper stratosphere to avoid high barometric pressures and weather conditions.) Smaller balloons/airships or heavier-than-air vehicles could then deploy from the orbital airship's cargo bay to peruse the planet at will.\nTo return to space, the orbital airship gradually builds up orbital speed & altitude over 2-3 days using solar-powered ion engines, rendezvousing with the main spacecraft.", "199" ], [ "I foresee hollow protoplanets!\nSince this species develops in a free-fall environment within a space-based cloud of gas littered with resource-rich/-poor asteroids, the first major structures will be built on the asteroids for mining operations. Individuals rarely want to travel long distances to get to work (long is, of course, relative in space), so housing will be built on the same asteroid as the mining facility. As the facility grows, it will need access to more resources, so either the company will start another mining facility or haul other asteroids to an existing one.\nClumps of asteroids then become the foundation for larger settlements, which attract more attention, more business, and more inhabitants, which bring in more asteroids to support the growing population.\nIndependent facilities will produce a similar effect, though in this case \"clumps\" will be individual asteroids connected via trade routes. The collections will attract attention, which brings in business, inhabitants, and more facilities. To prevent unwanted drifting, asteroids would be tethered together to emphasize established trade and transport routes.\nIn either situation, the city is developing in three dimensions, expanding roughly evenly in all directions.", "788" ], [ "This produces a spherical structure, with the oldest buildings at the center.\nTethers and nuts and bolts should be quite capable of holding things together; after all, they do quite well under constant gravitational stress from Earth.\nThe common architecture is going to be something much like what's on the ISS. There's no real down direction, so doors can be in any flat surface, possibly even in cones, corners, or hemispheres. In the case of asteroid clusters, paths of travel will be delineated by the structures themselves, where walls and solid connectors work together to create tunnels through the whole structure. In the case of asteroid collections, paths of travel will, in the macroscale, be defined by the inter-asteroid tethers, while local conditions will be like those for asteroid clusters.\nThe tethers and pipes used to connect structures and asteroids can double as infrastructure. Tethers can provide electricity and fiber optic cable. Pipes supply fresh water and remove waste.\n(All of this ignores the viability question of your scenario, which I am in no way capable of answering.)", "99" ], [ "I don't think a Type II civilization would build a Dyson Sphere because I don't think Dyson Spheres are very practical. <PERSON> explained some of the physics/engineering advantages of a ring over a sphere in Ringworld, so it seems more likely that a Type II would build one of those instead (and <PERSON> had to invoke implausible materials science just to hold the ring together). Of course, if you don't want to actually live on the Dyson sphere, you can have much looser constraints, but you still have the stability problem (active management of the sphere's distance from the star).\nThe main trick with a ring is that you want to spin it for stability (which helps maintain the shape, but doesn't do anything for the orbit/position relative to the star). A ring perpendicular to the ecliptic would occlude the sun 2x a year, unless you also spun it with the earth (but that would introduce a bunch of forces that you probably don't want to deal with). However, if you can engineer a ring that large, you can probably come up with a way to maintain a moving hole that lets the earth-bound light through.\nThe real question is whether a Type II civ needs to build a Dyson Sphere/Ring. If you build one small and close to the star, for energy only, you need to beam it around to where you want to use it.", "477" ], [ "While the sun is giving you a lot of \"free\" energy, it seems more plausible that such a civ would prefer to generate the energy more local to the point of use, and would likely be able to harness fusion energy at much smaller than stellar scales. Even a \"micro-star\" near home planet orbit would probably be more convenient than aiming a giant stellar-energy maser at/near Home.\nHowever, a Dyson Sphere may be constructed not for civilian use, but for military defense. The civ may deem it necessary to focus their entire star's energy to power a \"stellar X/gamma-ray cannon\" to deter/repel enemy invasions of their solar system. Whether this involves focusing the stellar energy with arrays of mirrors/lenses, or capturing it and converting it directly via a massive laser, the point is that Type II civs must believe that other spacefaring races may one day visit them, with less than peaceful intentions. Being able to blast them out of your solar system with the full power of your star may be considered an essential first step to becoming a credible interstellar civilization.\nAs others have noted, such a system can very likely be built out of a medium-sized planet or less--surely with the materials we see in most extra-solar planetary systems. And if you care about Home, it should be apparent why you build this device around Home Star and not Elsewhere.", "99" ], [ "I believe that a realistic answer to this will heavily depend on your universe's current understanding of human sleep patterns. Historical records indicate that prior to the easy access to artificial lighting, people used to sleep in two, 4-hour chunks, separated by a waking period of 1-2 hours. A psychiatrist's experiment in the 1990s confirmed this pattern. One study indicated that access to artificial light has shortened our sleep periods by about an hour; seasons also caused variation.\nThe best long-term case studies that I know of for someone living in a completely artificial light environment occurred over a period between 1962-1972 by the French scientist <PERSON>. In 1962, he spent two months in a cave, notably without access to a clock or calendar, in an attempt to determine what natural biorhythms would develop in such an environment. In 1972, he repeated the experiment, staying in a cave for six months. For those interested in reading more, the latter experiment was covered in the March 1975 issue of National Geographic in a piece entitled \"Six Months Alone in a Cave\" (summarized here).\nPhysiological effects included:\n* developing an extended 25-26 hour sleep/wake cycle, with some occurrences of a 48-hour sleep/wake cycle (36 hours awake, 12-14 hours asleep)\n* a subjective experience of the passage of time; he experienced it ~2x slower than it was in reality (from the 2-month experiment)\nThere have also been other experiments done as test runs for living in space habitats.", "551" ], [ "The Russian MARS-500 isolation experiment between 2007-2011 simulated a 105-day stage and later a 520-day mission; it's assumed that this closed habitat had no access to natural light. The data on physiological changes is sparse, but articles indicate that circadian rhythms were effected, and that in general, astronauts are plagued by sleep issues.\nWhat do we do with all these facts?\nYou'd need have some semblance of conformity to a natural sleep cycle unless you want your residents chronically fatigued, irritable, etc. There would be natural limits to wake periods due to physical exhaustion, of course (if we're ignoring biomedical enhancements or pharmaceuticals).\nShift systems might be based on the length of an orbital cycle, if the artificial environment is orbiting a planetary mass. This could be merely for convenience's sake, if the station is coordinating with people working on the planet who are subject to a more traditional day/night cycle.\nMaterial resources are also a consideration; in <PERSON> recent science fiction novel Seveneves, he posited that staggering wake/sleep cycles across a space station's population would prevent a strain on life-support systems and allow it to support a larger population. This did allow for some overlap between people on different \"shifts\", for work collaboration & social interaction. Special attention was paid to being cognizant & respectful of seeking someone's attention during their sleep period. In your universe, this could be imbued via the development of cultural practices and the implementation of shared calendar/contact systems that warned someone if they were trying to digitally interact with a person who was in a sleep period.", "551" ], [ "The only way I can see how this can occur is if the skull of the valkyries possess a circular magnet and their halos are wide-temperature-superconducting bioluminescent dandruff-like substance that clump together to follow the circular region of optimal magnetic flux. Okay. Let me break it down.\nToroidal Magnetic Field of Optimal Flux\nThe skull of a valkyrie has a circular portion lined with magnetic materials that was evolved from the time they used to migrate from one side lf their world to another. Think of this magnetic skull as a supersensitive biological compass. Possible enough to derive such structures from mihratory birds since your valkyries are basically winged humanoids. The average magnetic field of these materials form a region of strong magnetism shaped into a circle that forms above the skull.\n<PERSON> on Hair/Scalp/Feathers\nSome of the cells found in the hair and scalp and feathers of valkyries glow after they are shed and mixed in with particulate matter like dust and dirt in the air.", "671" ], [ "It turns out that once these cells are shed, they became wide-temperature superconductors that stay flux-pinned into magnetic field sources regardless of temperature changes.\nI admit those two components are a little too overcomplicated to pass as scientifically sound and naturally evolve-able, but imagine the scenario they can create for your valkyries, when they learn to exchange synthetic materials to decorate their halos.\nHalo Accessories\nHalos once appeared as natural as uncombed hair. They are messy, incomplete, but still a byproduct of weird valkyrie biology that got a bit too beautiful to even change. Young valkyries have at least a small arc of glowing superconducting dandruff. This small arc gets denser, accumulating and forming a complete circle that maintains its shape as the valkyries ages. Apart from the fact that stolen halos are easy to distinguish since they wobble on heads that are not naturally fitted to them, halos can be a sign of merit. They show just how often and how long a valkyrie has been working hard that their skin literally falls off, and then glows, and then floats, and then forms into a circle crown that proudly and firmly hovers above the head of a distinguished valkyrie.", "671" ], [ "Pretty much all flight on Earth relies - unsurprisingly - on gravity, so there aren't a lot of examples we can go with from Earth's flying species. We can get a few ideas from aquatic species that might be more useful, but air and water are quite different environments in terms of viscosity, so 'swimming' through air is unlikely to be useful. Still, there are probably analogs depending on the ecology of your world.\nFor this I'm going to assume that there are air currents of some sort in the gas envelope/atmosphere. This seems to be necessary to allow a proper respiration cycle and prevent atmospheric stagnation. I'll leave it to you to explain how those air currents work, I'm just interested in their effect on life forms.\nGiven those air currents we can start with microscopic airborne algae, similar to the phytoplankton you find in Earth's oceans, that forms the basis of your ecology. Drifts of algae will be carried along by the air currents, possibly forming visible dust clouds, probably limiting visual range in high density areas.\nAlong with the algae swarms you could add other lightweight plant forms, structured to be carried along on the breeze. They'd be fluffy, spherical masses with leaves (green if chlorophyll is dominant, depending on ambient light conditions) on the outside and root mats on the inside that capture particulates and moisture from the atmosphere. I imagine there's at least one variant of this plant that grows to be a large hollow sphere that floats along, possibly carrying small animals and other things inside and out.\nSimple animal life can use the air currents as well, simply floating along with very little actual motion. Larger, denser bodies will be less affected by the currents, so in algae-rich areas the food will be passing by on the breeze. Passive capture of nutrients in this way could support fairly large animal forms, since their energy use is very low.\nMore active animal forms will need to develop from more mobile precursors. Amoeba with cilia and flagella for motion are fairly common on Earth, and there's no reason they couldn't develop in your world. Simple forms grow and become more interesting.\nNow that we have the basics, we can start theorizing on the developments.\nFloaters\nAlgae, plants and drifting collectors just need to float in the breeze. They don't need any motive power since their movements are controlled by the air currents.", "731" ], [ "Some drifting collector-class creatures may have fins or other aerodynamic features to better orient themselves, but these can be purely structural with little or no control.\nFloaters also includes baloon-type creatures, like the Portugese Man-O-War jellyfish. A lot of variation is available there, from large single bags to hundreds of tiny gas cells. Gas can be generated biologically, through symbiotic bacteria or drawn directly from the surrounding atmosphere using a bellows arrangement.\nSailers\nExtend the aerodynamic surfaces on a floater and add more control musculature and you can better control movement through the air streams. Being able to tack against the wind makes a sailer more able to maneuver to greener pastures.\nUndulants\nSails become active surfaces that use rippling motion to push against the air, allowing the creature to move against the airflow or in areas with low air movement. Think of how cuttlefish fins work, but much bigger. Also imagine ribbons and carpets that undulate in the air, using cilia on their surfaces to increase air resistance. Might look something like how snakes do when they're moving through water or over sand.\nJets\nSimple balloons move well with the breeze, but with a little effort the internal gasses can be pressurized and used to maneuver. Over time a variety of animals of all sizes can develop from here, from simple mobile spheres to fast hunters that draw in air, pressurize it, then push it through directional nozzles. With the right sort of multi-stage pressurization this could even be a sustained flight model.\n(Juvenile jet-based creatures would have to be strongly familial since they'd be completely helpless until they learn how to control their jets. Packs of baby jets would probably be terribly cute.)\nOpposed Wings\nWhile Earth-formed wings use gravity, wings in this environment would need to have some other opposed force. Rather than having pairs of wings pushing 'down' and providing aerodynamic lift, a set of opposed pairs of wings pushing against each other would work as well. This could work well for insect-like forms, but other large creatures could benefit from it as well. A bird with four wings and a pair of tail surfaces would work well.\nInstead of simple pairs you could have a ring of wings where each wing opposes both of its neighbours during the full cycle. This would be quite maneuverable but potentially not as fast.\nFlapping Umbrella\nI don't know what else to call this.", "671" ] ]

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[ [ "Ethiopia Imposes Nationwide Internet Blackout · Global Voices\nAn October 2016 protest in London by Oromo people over killings and human rights abuses at the hands of the Ethiopia government. Photo by Flickr user <PERSON>. CC BY 2.0\nOn May 30 at 3pm local time, Ethiopians found themselves unable to access the Internet. The blackout appears to be country-wide.\nIt appears that Ethiopian authorities imposed the nationwide Internet blackout in order to prevent “leaking of exam questions on Facebook” ahead of secondary school exams set to be administered over the next two weeks.\n24 hours after the total Internet blackout, Ethiopia still refuses to say why it shut down. Via @AFP pic.twitter.com/ZzJcX6Vqe8\n— <PERSON> (@zelalemkibret) May 31, 2017\nTwenty-four hours after the blackout, Deputy Communication Minister of Ethiopia <PERSON> told AFP that mobile data also had been deactivated.\nFinally, the Ethiopian government announced that the internet blackout will continue until June 8, 2017, reasoned by fear of ‘exam leaking’.\n— <PERSON> (@zelalemkibret) June 1, 2017\nLast year, the government was forced to postpone the national university entrance exam after the initial session was marred by a leak spread on Facebook.", "960" ], [ "Activists in the diaspora leaked questions on Facebook ahead of the exam in early June in 2016 after the government refused to re-schedule the exam for students who missed an entire semester of classes due to protests.\nBut the current blackout is different from previous mobile Internet and social media shutdowns that have been imposed in an effort to prevent exam leaking. This blackout is broader in scope and scale, effectively eliminating Ethiopia from the map of the global Internet.\nThis is especially easy for the Ethiopian government to do, since all Internet and phone service in the country is provided through through a single government-owned Internet service provider, Ethio Telecom. The blackout thus leaves businesses, banks, Internet cafes in Addis Ababa and social media pages of government media cut off from the rest of the world, making it harder for them to do their day-to-day work.\n‘Cos of the blackout: Banks are out of service, Bulk SMS services are not available, GPS services are not accessible …\n— <PERSON> (@zelalemkibret) May 31, 2017\nThe gravity of this move begs the question: Are authorities really just trying to prevent students from cheating on exams, or is there more to it? Indeed, this is just one among various reasons that Ethiopian authorities have used to justify censorship and shutdowns in recent years.\nEthiopia has blocked the Internet on three occasions since huge anti-government protests exploded in November 2015. Mobile and landline phone networks are also crippled in much of the country’s two biggest regions, Oromia and Amhara, where anti-government protesters have become common over the last two years.\nWhen Ethiopian authorities declared a state of emergency in October 2016 they officially blocked access to Facebook, Twitter and popular messaging apps such as Viber and IMO. Since Internet speeds are already incredibly slow, data-heavy video platforms such as YouTube have been rendered inaccessible even though they are not officially blocked.\nJust two weeks ago, activists inside the country reported that they were finally able to access Facebook freely, after many months of using VPNs and other circumvention tools to login to the social network. But with the country now in total blackout, they are now even more isolated from the rest of the world, and even from each other, than before.", "960" ], [ "Ethiopian Protester Sentenced to Six Years Behind Bars for Facebook Posts · Global Voices\n<PERSON>. Photo shared on Twitter by <PERSON> @eyasped\nThis week in Ethiopia, two prominent human rights advocates and critics of the ruling government were given long-term prison sentences for “incitement” on Facebook.\nOn May 25, <PERSON> was sentenced to six years and three months in prison for “inciting” antigovernment protests in nine Facebook updates.\nBreaking: #Ethiopia fed court sentenced former oppos'n Blue party PR head <PERSON> six years & 3 months in jail for terrorism pic.twitter.com/LQKqVh1wne\n— Addis Standard (@addisstandard) May 25, 2017\nThe 30-year-old activist has been an outspoken opponent of government’s violent response to the popular protest movement that has challenged Ethiopia’s ruling party and government since 2015. <PERSON> had previously served as a press officer for the leading opposition Blue Party before resigning in 2015.\n<PERSON> was jailed for nine Facebook posts that expressed solidarity with the protesters, called for open dialogue and pleaded for an end to the violence.\nThe day before his sentencing, <PERSON>’s former colleague <PERSON>, was found guilty of inciting violence for a private message he sent to colleagues through his Facebook messenger app. The former editor-in-chief of opposition newspaper Negere Ethiopia, <PERSON> was sentenced to one year and six months in prison:\nBreaking- #Ethiopia court sentenced <PERSON> editor-in-chief of Negere Ethiopia NP, to 1yr & half in jail, time he already served pic.twitter.com/Pzp3dXCK6A\n— Addis Standard (@addisstandard) May 26, 2017\nThe Facebook message that allegedly contained inciting content made reference to a heckling incident targeting late Prime Minister <PERSON> at a 2012 symposium in Washington, D.C. In the message <PERSON> wrote, “since the political space in Ethiopia is closed heckling Ethiopian authorities on public events [sic] should be a standard practice.”\nThese cases are among many others of less well-known citizens who have spoken out against the regime's violent targeting of protesters demanding protections for land rights and other fundamental freedoms. According to Human Rights Watch, at least 800 people have died at the hands of Ethiopian police, and thousands of political opponents have been imprisoned and tortured during the protests.\nFacebook is a key tool for activists — and law enforcement\nFacebook, along with other social media platforms, has had a central role in interactions between authorities and protesters. Ethiopian authorities have blamed social media for waves of protests that began in April 2014 and have continued ever since. In October 2016, Facebook was blocked in Ethiopia as part of the government's state of emergency. But activists — and likely Ethiopian law enforcement — have continued to use the platform via VPN.\nAlthough it is difficult to know the precise number of detainees, dozens of arrests appear to have been triggered by a person posting, liking or sharing a post on Facebook.", "799" ], [ "Others have been arrested for communicating with diaspora-based activists through Facebook messages.\nThese cases have been compounded by an increasingly common practice in which Ethiopian authorities demand that detainees divulge their Facebook logins and passwords. In some cases, people have been arrested before being charged, forced to hand over their Facebook credentials, and then charged based on what authorities find in their accounts.\nPolice will arrest activists, force them to hand over their Facebook credentials, and then charge them based on what they find in their private message logs.\n<PERSON> was charged with “inciting violence” after he was forced to give his username and password of his Facebook page. The private chat texts on his Facebook message were presented as evidence in his charge sheet.\nWhatever the court decides, friends and family members of <PERSON> and <PERSON> wanted the case to end. So, they would learn their fate, to take their fight to the next stage. But their case, like so many others court cases, had been delayed.\nIn Ethiopia, it is not uncommon for court cases involving bloggers journalists and politicians to take longer than other cases. This causes exhaustion for defendants and brings pain to their loved ones.\n<PERSON> and <PERSON> each spent 18 months in jail before they learned their fate. They were brought before the court at least a dozen times. Their private Facebook accounts were laid bare by authorities. Judges failed to appear in court, and police failed to bring defendants to court on their trial days, causing their cases to drag on for 18 months.\nFacebook has been a critical platform for Ethiopian activists and rights advocates working to document and communicate human rights violations.", "409" ], [ "Residents of Ethiopia’s Oromia Region Strike to Demand Release of Political Prisoners · Global Voices\nClosed shops and deserted streets in Bale Robe, a town in Eastern Ethiopia. Photo sourced from <PERSON> Facebook page and widely shared on social media.\nThe Oromos, Ethiopia’s single largest ethnic group, collectively rallied against Ethiopia's ruling regime on Wednesday, August 23, this time by staying at home, skipping work and refusing to open their businesses.\nThe towns and cities of Oromia, Ethiopia’s largest administrative region where the Oromo people are concentrated, are normally bustling. But photos shared on Facebook showed shopping centers and open markets were largely quiet on Wednesday and Thursday. Roads were nearly empty, and public transportation services providers such as buses stopped, forcing government workers who had no other way of reaching their post to take part in the protest.\n#Breaking: Harar and its surroundings under strike; no trade and transport activities observed. Some damaged vehicles were also spotted. pic.twitter.com/YmyOSIt2Tk\n— The Reporter (@TheReporterET) August 24, 2017\nThe strike, which is set to last for five days, was called by a mysterious Oromo youth movement calling themselves “Qeerroo,” referring to their youthfulness in the Oromo language.\nThe secretive activist group’s main demand is the release of political prisoners and jailed activists, in particular prominent opposition figures such as <PERSON> and <PERSON> who were arrested over the last two years of protests and charged with crimes such as terrorism and promoting “regime change using illegal forceful means and threats”.\nTwo years ago, thousands across Ethiopia mainly in the Oromia and Amhara regions rose up, demanding more political freedoms and social equality and a stop to government land grabs. In terms of representation, Oromos make up 35 percent of the country’s 100 million people and Amharas account for about 30 percent of the population. The Tigrayans, on the other hand, represent only 6 percent of the population, yet Tigrayan elites are among the most high-ranking military officers who control the nation's security.\nThe government's response to that uprising was brutal; hundreds were killed and thousands arrested.", "960" ], [ "In October 2016, authorities declared a nationwide, nine-month state of emergency that was lifted on August 4, 2017.\nWith this recent strike, the Qeerroo also want an end to what diaspora-based activists say an unjust tax hike. In July 2017, the government introduced a new tax scheme for small business operators across the country that prompted a similar protest both in the Oromia and Amhara regions. That protest in July quelled without any demonstrable political results, but the demand has resurfaced here.\nAlso, in the middle of all of this, the Oromos have a border dispute with the neighboring Ethiopian Somali. In April 2017, during the state of emergency, the Ethiopian government told the two regions to come to an agreement redistricting their boundaries per the outcome of a referendum that was conducted 10 years ago, in which Oromia lost some land. The government recruited “Liyou Police” or special police of the Somali region as an armed force to enforce the outcome.\nThe Oromos saw this as a plot of the Tigryan elite to weaken them, and they accuse Liyou Police of human rights violations. Ending the alleged human rights violations is contained within demands of the ongoing peaceful protest.\n#Ethiopia – call for an end to “Liyu police anarchy” in #Oromia as stay-at-home strike spreads through the region https://t.co/GbY1YcRhz0 pic.twitter.com/BNnsZ0gnQA\n— Addis Standard (@addisstandard) August 24, 2017\n‘It should be waged at a national scale’\nThe <PERSON> reach to their audience entirely through Facebook, a website, and diaspora-based satellite television networks. <PERSON>, executive director of Oromo Media Network, appears to be a major source of information. His Facebook page has more than one million followers, most of them gathered over the last three years.\nThe only apparent major information hub focusing on the current protest is the Facebook page of America based Oromo activist <PERSON>.\n— <PERSON> (@ZekuZelalem) August 23, 2017\nThe ongoing protest underscores the rise of a potentially treacherous challenge to the ruling Ethiopian People's Revolutionary Democratic Front (EPRDF) monopoly of power: widespread public outrage and a growing willingness of the public to participate in a strike when they are called.\nBut there are concerns about the absence of a single compelling protest message, coming even from supporters of the cause.", "960" ], [ "Months after pledge to open internet, Ethiopia disrupts connectivity amidst communal violence, tension · Global Voices\nEthiopian Prime Minister <PERSON> sits with Minister of Defense <PERSON>, November 24, 2017. Photo by <PERSON> via Wikimedia Commons CC BY 4.0.\nThis story is the second in a two-part series on online disinformation, shutdowns, and rising political and ethnic tensions in Ethiopia. You can read the first part here.\nOn June 18 of last year, in his second parliamentary address, Ethiopia’s reformist Prime Minister <PERSON> announced his government would no longer block online publications. Within a day, his then-chief of staff, <PERSON>, followed up in a tweet acknowledging the unblocking of more than 250 largely diaspora-based, pro-opposition websites and blogs.\nAt that time, the move was celebrated as a major step toward internet freedom in a country where the ruling regime, the Ethiopian People’s Revolutionary Front, (EPRDF) had for years controlled the flow of information.\nAs the political environment relaxed, comedians, journalists, bloggers and opposition activists voiced thoughts and criticisms that had been bottled up for decades. Ethiopia's embrace of civil liberties, however, has deflated as political rifts resurfaced between non-ruling elites of Ethiopia's two main ethnic groups: the Amharas and the Oromos. With ethnic and political tensions between the two groups manifesting online in the form of hate speech and disinformation, the government responded — on a number of occasions — by imposing restrictions on access to networks and social media platforms.\nPrior to the political reforms introduced by PM <PERSON>, disruptions of internet connectivity, cell phone services, or social media occurred for reasons ranging from curbing mass protest demonstrations to preventing cheating during examinations.\nThis time around, although politics is at the center of internet shutdowns, the dynamics are more complicated than they had been prior to the start of the political reforms.\nDeadly communal violence and a shutdown\nView over Churchill Road in Addis Ababa, Ethiopia. Photo by <PERSON> via Wikipedia.\nIn September 2018, just two months after the government's pledge to open up the internet, deadly communal violence erupted in Burayou, a town located in outskirts of Ethiopia’s capital, Addis Ababa, following the homecoming of two exiled political groups in competition with each other: Patriotic Ginbot 7 and Oromo Liberation Front (OLF).", "960" ], [ "In response, the government resorted to large-scale, deliberate disruptions of internet connectivity, cell phone service, and social media.\nAuthorities believe social media — particularly Facebook — played a central role in stoking communal tension, and they are not alone. The fact that communal tension hit a boiling point in Burayou just as social media made inroads in the area drove many to speculate that the violence was stoked by messages shared on social media.\nHowever, a closer look at the violence reveals there are other deep-rooted factors, too.\nIn recent years, communal tensions have been a fact of life in Ethiopia. Among the many ethnic tensions that dominate Ethiopian politics, perhaps none have been as caustic as the issue of Addis Ababa, Ethiopia's capital city, around which conflict and tension have been building for years.\nAddis Ababa, geographically located in Oromia, is predominantly Amharic-speaking and continues to expand into Oromia, Ethiopia’s largest administrative region.\nIn reaction to the persistent expansion of Addis Ababa into Oromia until 2014, a protest movement started in 2015. After years of struggle, these protests slowed down the expansion of the sprawling city.\nBut the protest movement’s initial claim of halting the unrestrained expansion of Addis Ababa at the expense of Oromo farmers eventually evolved into nationalistic claims defined in terms of ethnic ownership of the city.\nIn the days leading up to the communal violence in Burayou, the supporters of the two rival political blocks spread an “us-versus-them” philosophy through various means of communication. They hoisted and waved flags and banners of the competing groups in the streets of Addis Ababa. There were even physical confrontations and a few violent clashes in the capital.\nWhile many factors contributed to the communal violence in Burayou, such as ethnic and linguistic divides and a lack of faith in the government, the internet was singled out to blame as the main reason.\nThis was the second time (as per available information) that internet services were suspended after authorities promised the government would no longer block the internet nor restrict access to specific apps or websites.\nAuthorities also shut down the internet on grounds of security or public order measure when ethnic violence broke out in eastern Ethiopia in August 2018. Authorities only reversed their decision after a short-lived positive turn — following the political reforms that began in April 2018 under <PERSON>.", "960" ], [ "Ethiopia’s Human Rights Commission Admits Protesters Were Killed, but Shifts Blame Away From Government · Global Voices\nAn October 2016 protest in London by Oromo people over killings and human rights abuses at the hands of the Ethiopia government. Photo by Flickr user <PERSON>. CC BY 2.0\nThe Ethiopian government's Human Rights Commission has declared that 669 people were killed during the uprising of 2016, a figure that is significantly lower than other numbers reported by Human Rights Watch and Amnesty International.\nThe unveiling of the report took place on April 18 in a parliament that is completely controlled by the government. <PERSON>, the head of the Ethiopian Human Rights Commission, read out the commission’s main findings to Ethiopian parliament, which placed the burden of responsibility for the bloodshed largely on opposition groups: “The violence happened because protesters were using guns and security forces had no other options”. <PERSON> said the “negligence” of security forces was also a contributing factor, albeit a minor one.\nSeveral human rights organizations, however, have reported that it was largely security forces firing on unarmed demonstrators.\nUntil the movement was subdued in October 2016, when Ethiopia declared a state of emergency, thousands had been demonstrating across Ethiopia. The protests began in April 2014 in Oromia, the largest of nine ethnically federated states, against a plan to expand the territorial limits of Ethiopia's capital, Addis Ababa, into neighboring Oromia villages and towns. The Oromo people have historically been persecuted by those in power in Ethiopia, and the plan was viewed as yet another encroachment on their rights. Over the following months, the protests expanded into other states, with participants rallying behind broader grievances against the government.\nThe government responded brutally; according to Amnesty International, at least 800 people were killed, while opposition groups and activists put the figure in the thousands.\nThe report as told by <PERSON> blames opposition groups, diaspora-based satellite television stations, particularly Oromo Media Network, and social media for exploiting the prevailing “lack of good governance” in Ethiopia to stir violence.\nThe long-awaited report of the Human Rights Commission's investigation is not available on its website; the state-affiliated Fana Broadcasting Corporate did not provide a link to it in their news report either.", "960" ], [ "However, Al Jazeera has embedded a video that shows <PERSON>’s presentation in parliament. Most of the news reports are based on the summary that was presented for the parliamentarians, which focused largely on the number of people killed and the losses to property.\nThe news reports did not indicate if the commission’s report addressed torture, arbitrary detention, and poor prison conditions. International organizations like Human Rights Watch, Amnesty International, and Freedom House often point to evidence that shows these issues are rampant in Ethiopia. Similarly, the Ethiopian Human Rights Council, the only independent local human rights organization in the country, has also reported their prevalence.\nBut concrete information about torture, arbitrary detention, and prison conditions have been elusive in past reports from Ethiopia’s Human Rights Commission.\n<PERSON>, who himself spent at least four months in prison during the protest, wrote in response to the report: “God Save Us from Subservient Human Right Commission that intimidates the public”.\nA day before the release of the report, Ethiopian officials rejected requests by the United Nations and the European Union to send independent investigators to consider the alleged human rights violations. Speaking to BBC Africa, Ethiopian Prime Minister <PERSON> said Ethiopia has independent institutions that can do such investigations on their own.\nHowever, a closer look at the chairperson of the Ethiopian Human Rights Commission <PERSON> reveals that he has substantial ties to the government and a significant interest in maintaining the status quo. Previously, <PERSON> held posts in the Ministry of Federal Affairs and was a deputy chair of the Ethiopian National Electoral Board that supervised the May 2015 parliamentary election, which was won by the ruling party, the EPRDF. The opposition complained of irregularities during and in the lead-up to that vote.\nSince November 2015, Ethiopia has followed a devastating cycle of protests and repression. The country's Human Rights Commission published the findings of a similar investigation last June, but in it those responsible for the killings were not held to account, and protests abated only in October 2016 when authorities declared a state of emergency. With Ethiopia’s prisons full of political opponents, the latest report will likely only deepen the impasse if it also fails to address the root causes of the discontent.", "409" ], [ "For Opponents, WHO Director General Nominee <PERSON> Represents Ethiopia’s Repressive Government · Global Voices\nDr. <PERSON>, Minister of Health, Ethiopia, speaking at the London Summit on Family Planning in 2012. Photo by Flickr user UK DFID. CC BY-SA 2.0\nSome Ethiopians are fiercely campaigning against <PERSON>, Ethiopia’s candidate to replace <PERSON> <PERSON>, as director general of World Health Organization, just a few weeks before member states are set to vote on the final three candidates.\n<PERSON>, a former Ethiopian foreign and health minister, along with Pakistan’s <PERSON> and the UK’s <PERSON> are the three director-general nominees who made the cut from a larger pool of candidates in January.\n<PERSON>, who is running a well-funded campaign, is considered as a prime contender in the race. His candidacy was endorsed by the African Union, and just last week he picked up an endorsement of <PERSON>, the UK’s former international development secretary.\nHowever, he is facing unrelenting opposition from his own citizens.\nEthiopians who feel marginalized by their country's government are campaigning hard against him online, arguing he should not be elected because he represents the interests of Ethiopia’s autocratic ruling elites and not the people.\nThe irony is beyond tragic. The person who is responsible for the crimes against humanity in #Ethiopia is running for #WHODG! #NoTedros4WHO\n— <PERSON>@kiruskyy) April 28, 2017\nThey have set up online petition pages against <PERSON> and produced a documentary film detailing what they consider to be his failures and his alleged mismanagement of funds while he was Ethiopia’s health minister.\n<PERSON> presided and participated in the biggest financial corruption scandal of misusing Global fund in Ethiopia. #NoTedros4WHO\n— Amsalu (@AmsaluKassaw) April 28, 2017\nThey have organized Twitter campaigns under a hashtag #NoTedros4WHO to organize conversations surrounding the topic. To make his Ethiopian government profile at the top of the public’s consciousness, his opponents have share detailed research that accuses <PERSON> of inefficiencies, misreporting, and exaggerations of his achievements when he used to serve in Ethiopia.\nOne of the images that have circulated against <PERSON>, showing his face with an X over it next to the two other candidates. Shared by Twitter user <PERSON>, amid fears that the campaign might diminish his chances, government groups are also running a parallel campaign supporting his candidacy. They have downplayed the opposition as unpatriotic, mean-spirited and trivial jealousy.\nSince April 2014, a popular protest movement in Ethiopia has challenged the government, which has responded brutally.", "960" ], [ "According to Human Rights Watch, at least 800 people have died, and thousands of political opponents and hundreds of dissidents have been imprisoned and tortured. Since October 2016, authorities have imposed some of the world’s toughest censorship laws after it declared a state of emergency.\nThe role of ethnic politics\nSome of <PERSON>’ detractors say they oppose his candidacy because of his alleged incompetence. But a big part of what drives the fierce opposition to <PERSON> is the logic of ethnic politics.\n<PERSON> holds a Ph.D. from the University of Nottingham in community health. He studied biology at Asmera University before he completed a master’s degree in immunology of infectious diseases in London.\nWhen people hear his name, as qualified as he may be, his opponents associate him with a repressive Ethiopian government that has killed people, jailed thousands of political opponents, and imprisoned and tortured dissidents.\nHis meteoric rise to power started soon after he finished his Ph.D. in 1999 when he was tasked to lead the Tigray region’s health department. After two short years in Tigray, he was promoted to Ethiopia’s minister for health by the late prime minister <PERSON>, a Tigrayan himself. In 2012 when <PERSON> died, <PERSON> became Ethiopia’s foreign minister.\nTigray is one of the nine regional states that are federated based on ethnolinguistic compositions.\nOver the past 26 years, the Tigrayan elites have taken center stage in Ethiopia’s political affairs, largely due to their control of the military, security and the economy of Ethiopia. Though accounting for only 6% of Ethiopia’s population, all senior positions of country’s military and security and the most meaningful positions in state institutions are packed by Tigrayan elites. This has always been a sore point with the elites of the Oromo and Amhara ethnicities, who together comprise 65% of Ethiopia’s population.", "409" ], [ "Everybody Is Hailing Billboard-Topping Musician <PERSON>, Except Ethiopian State Media · Global Voices\n<PERSON> live in concert. YouTube video.\nEthiopian pop singer <PERSON>, better known as <PERSON>, was all set to be the subject of a highly-promoted interview with Ethiopian state broadcaster EBC, before authorities suddenly pulled the plug.\n<PERSON> interview was scheduled to broadcast on Sunday, May 14, with the artist expected to discuss the success of his latest album,'Ethiopia’, which is currently sitting at the top of Billboard’s “World Music Chart”. But <PERSON>, a veteran government journalist confirmed on his Facebook page on May 12 that the interview would not be aired.\nEthiopian authorities are regular culprits of political censorship, targeting journalists and artists alike.", "23" ], [ "<PERSON>'s songs are often critical of the Ethiopian state.\nBefore <PERSON>'s Facebook post, the state broadcaster had quietly removed a short video containing a promotional excerpt from the interview with <PERSON> from its Facebook page.\nhttps://globalvoices.org/wp-content/uploads/2017/05/Teddy-Afro-New-Interview-on-EBC-Ethiopia-ቴዲ-አፍሮ-ቃለ-መጠይቅ-በኢቢሲ.mp4\nJust hours later, <PERSON>, another pro-government journalist wrote on Twitter that the interview is back on, but the broadcaster has refused to confirm or deny that statement.\nAt last! EBC reached in a decision to air <PERSON> Interview\n— Awramba Times (@AwrambaTimes) May 13, 2017\n‘Ethiopia’ stormed to number one on Billboard's World Music albums chart following record-breaking sales both internationally and domestically. Since <PERSON> released the title song on his YouTube Channel on April 16, the song has racked up over three million views.\n‘Ethiopia’ is <PERSON>'s fifth album. All his previous albums were bestsellers in Ethiopia but his Billboard achievement is unprecedented for any artist from the country.\nFollowing the success of his album, <PERSON> gave interviews to different international media including Associated Press (the story was published in several major newspapers) and Voice Of America's Amharic service. He is also scheduled to appear on BBC Africa.\nIt was perhaps this surge in international interest that put Ethiopian state television under pressure to interview <PERSON>, despite state-affiliated media broadly ignoring his achievement up until that point.\nHowever, as fans waited in curiosity for the broadcast, the censorship machine did what it does best, and spoiled the party.", "23" ], [ "Leaked Documents Show That Ethiopia’s Ruling Elites Are Hiring Social Media Trolls (And Watching Porn) · Global Voices\nEPRDF rally in Addis Ababa in 2010. Photo by <PERSON>/BBC World Service via Flickr (CC BY-NC 2.0)\nOver the past two months, a series of leaked documents from Ethiopia’s powerful political elites have been circulating online.\nAmong other revelations, the leaks show that the Ethiopian government has been paying online commenters to influence social media conversations in the ruling party's favor. The documents include hundreds of pages of chat logs and email correspondence of Ethiopia’s top government officials, multiple government planning documents and top-secret meeting records.\nThe leaks have come at what may be a turning point in Ethiopia's recent political crisis. Since mid-2015, thousands across Ethiopia rose up, demanding more political freedoms and social equality and a stop to government land grabs in the Oromia region, which represents Ethiopia's largest ethnic group. The government response was brutal: Hundreds have been killed, thousands have been arrested, and critical voices — both on and offline — have been systematically silenced.\nAmong the recent leaks, which began to circulate on Facebook in November 2017, one of the most revealing documents is a list of individuals who appear to have been paid to promote the ruling coalition on social media. The list shows the names of the so-called “social media commentators” along with their job titles and a precise amount of money that they apparently received for their online postings. Most of the people listed are government employees.\nThe list corroborates previous evidence that the Ethiopian government has been hiring online commenters to promote its agenda and harass its opponents.\nOnline communities in Ethiopia have been calling these paid commenters “cocas”, a colloquialism in Amharic (the most widely spoken language in the country) that can be translated as “contemptible cadres.” In Amharic, this term typically refers to people who sell themselves for easy money. But in this case, most of the commenters listed in the leaked directory are already on the government payroll.\nWho is responsible for the leaks?\nThe origin of the leaks has been rumored and contested at several levels. The documents were originally sent to diaspora activists from the at least two Facebook accounts, both of which belong to government employees, in November 2017.\nThe first known leak, of the “coca” list, came from the Facebook account of <PERSON>, an employee of the communications affairs office of the Tigray state.", "960" ], [ "<PERSON> first denied sending the documents, claiming his account was hacked. But he then backtracked on this claim. It is now rumored that he has been dismissed from his job.\nSoon after the initial leak, more documents began arriving in the inboxes of diaspora activists, this time coming from the Facebook account of the Director of the Federal Communications Affairs office, <PERSON>. Shortly thereafter, <PERSON> began to publicly shame those government officials who are implicated in the leaks. On January 18, he denigrated Deputy PM <PERSON> in a public Facebook post.\nIt is unclear whether <PERSON> sent the documents himself have been hacked.\nSocial media ‘cocas’ push pro-government discourse\nThe revelations of political and state officials paying “cocas” to promote the ruling party agenda online correspond with a recent rise in polarization and hate speech on social media, alongside increased online persecution of independent journalists.\nThe leaked “coca” list reveals that at least thirteen commentators were each paid at least USD $300 (a large sum in Ethiopia, where average GDP per capita was USD $660 in 2016) for blog posts or Facebook messages that they wrote at the behest of the ruling coalition.\nList of paid internet commentators. Image widely circulating on Facebook\nAmong individuals named on the list are <PERSON> and <PERSON>, publishers of two Ethiopian internet news site HornAffairs and Awaramba Times respectively. The two journalists have long been accused of cheer-leading a pro-government information campaign especially during a heightened political tension.\nIn recent years, independent Ethiopian journalists reporting on government affairs, corruption and human rights have been arrested or exiled en masse. The resulting gap in news coverage has thus been filled by opposition activists and protesters who often work with diaspora-based media outlets to draw global attention to the brutal military crackdown on protesters that has killed more than 1200 people and has led to several mass arrests since mid-2015.\nOn the heels of the list came a separate leak of what appears to be a proposal to counter opposition groups using social media platforms. The Amharic-language document from the office of Ethiopia’s longtime governing coalition, the Ethiopian People’s Revolutionary Democratic Front’s (EPRDF), enumerates solutions and strategies to curtail the influence of online diaspora-based activists.", "960" ] ]

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[ [ "<PERSON> and <PERSON>, the authors of the paper on the possible planet, have a webpage addressing this.\nA few reasons not already covered:\n* It moves quite slowly - the authors estimate 0.2-0.6 arc seconds per hour - so standard surveys may not notice the movement and fail to recognize it as a solar system object.\nEris, which is the most distant confirmed object still known in the solar system, moves at a speed of 1.5 arcseconds per hour, which is so slow that it was missed the first time around. Most surveys of the outer solar system would not be able to find Planet Nine, even if it were quite bright, as they would just think it is a stationary star.\n* If the planet is near aphelion, it might be an order of magnitude further away than any major or minor planet we've found so far (excluding exoplanets, which are found by methods that don't apply in this case). The authors suggest an aphelion between 500 and 1200 AU. For comparison, Pluto is at 30-50 AU, while Eris at around 100 AU wasn't discovered until 2005. The potential 9th planet would be far larger than Eris, but is also likely to be much further away, and thereby fainter.\n* The WISE survey eliminated Saturn-sized planets within 10,000 AU, and Jupiter-sized planets within 26,000 AU. But the potential 9th planet is far smaller than those. WISE has also done a more sensitive search, which would pick up Neptune-sized objects, but that search has so far covered only a limited part of the sky.\n* The planet will be far harder to spot if it has the Milky Way in the background - there are too many stars potentially drowning out a faint object.\nHere's the authors' summary:\nEstimated orbit for the putative 9th planet. The horizontal axis is the right ascension.", "196" ], [ "The colored segments are regions where it should have been found by existing surveys.\nIllustration by <PERSON> and <PERSON>, assuming fair use applies.\nThe biggest unexplored territory is where, statistically, it is most likely to be: near aphelion. Sadly, aphelion is also very close to the Milky Way galaxy. Ugh.\nSo where is it? Probably distant. 500 AU+. Probably fainter than 22nd magnitude. Very possibly in the middle of the Milky Way galaxy.\nNow go find planet nine.\nMore details on the authors' webpage: http://www.findplanetnine.com/p/blog-page.html\nFinally, the gravitational dominance of the Sun reaches halfway to the nearest star. There's still plenty of unexplored territory for planets smaller than Saturn to hide in.\nNote the log axis. We have a good map for the inner 50 AU, and are starting to find objects around 100 AU, but solar system objects might exist all the way to the outer edges of the Oort cloud.\nIllustration from wikipedia.", "196" ], [ "There are no undiscovered planets between the sun and Neptune\nObjects closer to Neptune that are large enough to be considered planets (and not dwarf planets) can't remain 'hidden'. If it's there, the light from the sun will bounce off it and we will see it. As it moves in its orbit, we will notice the position in the sky change, so we will know it isn't a star.\nI would like to give a more broad answer to this question though: What is the maximum size of an undiscovered solar system object and how does it change as you get further from the sun?\nThe further out a solar system object is, the harder it is to detect. The rate at which it gets harder is severe; the light we receive from an object scales roughly as $1/r^4 $.\n($1/r^2$ for the light travelling from the Sun to the object, and again, $1/r^2$ for the light travelling from the object to us on earth).\nWe are able to detect some very small earth-crossing asteroids. Some as small as ~50 metres across. At a guess (and this is just based on my intuition, not any calculations), there are probably no undiscovered objects larger than 1 km close to earth.\nAs you travel to the outer solar system (Jupiter to Neptune), the number of bodies increases dramatically. There are currently ~700,000 known solar system bodies and most of them occur in this area. It is believed that all asteroids larger than 10 km have been found.\nIn the area immediately beyond Neptune (30 AU to 100 AU), we have been finding many pluto-like objects in the past two decades, objects with diameters of 500 km or more.", "710" ], [ "For reference, Pluto is about 2200 km across. It is entirely plausible that there are some, if not many, similar objects at this distance range that have not yet been found. Some of these would classify as dwarf planets, in that they are round, orbit the sun, but have not cleared 95% of their orbit of other matter.\nAnd finally - and this is where it gets exciting - where it gets really far out, there may be an undiscovered large planet, out at ~700 AU. Referred to as Planet Nine, this is a hypothetical object that some (noteworthy) astronomers believe exist because of patterns they see in the orbits of other distant dwarf planets. From calculations, they estimate that it would be as heavy as 10 earths and travel between 200 and 1200 AU. However, these distances are so large and the sunlight out there is so dim, that even with the best telescopes and two years of looking, they haven't found it.\nFinally, I'd like to share two graphs. The first one is of distance (of closest approach, or perihelion) vs diameter of various outer solar system bodies. In the bottom right corner there is a noticeable lack of dots, indicating roughly where we don't yet have the capability of seeing objects that small and distant.\nThe second is an expanded but slightly less accurate diagram of the same.", "196" ], [ "A few hundred kilometers beyond geosynchronous is the satellite graveyard orbit, which distance is also a function of satellite size. One could place an asteroid into such a orbit to be a quite visible moon. One can argue that since we do not have such a moon, that it is therefore improbable. However, as below, no moon is forever, and most assuredly in the past we had lots of little moons. Earth more or less has a sort of a second moon, and will for centuries so \"can't have\" is doubtful.\nI do not buy the \"I do not like the complicated orbit small temporary natural satellite argument.\" Using that argument, Phobos would not be a moon of Mars as its orbit will terminally decay in 30 million years.", "196" ], [ "Our Luna will eventually escape due tidal braking, so, I would prefer to say that no satellite is forever. The next problem is that if 2016HO3 above is not a 'moon' or 'satellite' then Earth is not a 'planet,' as planets 'clear their own orbits' as point 3 of the IAU definition of planet.\nThe Hill sphere is only an approximation, and other forces (such as radiation pressure or the <PERSON> effect) can eventually perturb an object out of the sphere. This third object should also be of small enough mass that it introduces no additional complications through its own gravity. Detailed numerical calculations show that orbits at or just within the Hill sphere are not stable in the long term; it appears that stable satellite orbits exist only inside 1/2 to 1/3 of the Hill radius. The region of stability for retrograde orbits at a large distance from the primary, is larger than the region for prograde orbits at a large distance from the primary. This was thought to explain the preponderance of retrograde moons around Jupiter; however, Saturn has a more even mix of retrograde/prograde moons so the reasons are more complicated...The Hill sphere of (66391) 1999 KW$_4$, a Mercury-crosser asteroid that has a moon (S/2001 (66391) 1), measures 22 km in radius.", "196" ], [ "It's too dim to be seen during a normal survey during the majority of its orbit.\nUpdate: Scientists at the University of Bern have modeled a hypothetical 10 Earth mass planet in the proposed orbit to estimate its detectability with more precision than my attempt below.\nThe takeaway is that NASAs WISE mission would have probably spotted a planet of at least 50 Earth masses in the proposed orbit and that none of our current surveys would have had a chance to find one below 20 earth masses in most of its orbit. They put the planets temperature at 47K due to residual heat from formation; which would make is 1000x brighter in infrared than it is in visible light reflected from the sun.\nIt should however be within reach of the LSST once it is completed (first light 2019, normal operations beginning 2022); so the question should be resolved within a few more years even if its far enough from <PERSON> and <PERSON>'s proposed orbit that their search with the Subaru telescope comes out empty.\nMy original attempt to handwave an estimate of detectability is below. The paper gives potential orbital parameters of $400-1500~\\textrm{AU}$ for the semi major axis, and $200-300~\\textrm{AU}$ for perihelion. Since the paper doesn't give a most-likely case for orbital parameters, I'm going to go with the extreme case that makes it most difficult to find. Taking the most eccentric possible values from that gives an orbit with a $1500~\\textrm{AU}$ semi-major axis and a $200~\\textrm{AU}$ perihelion has a $2800~\\textrm{AU}$ aphelion.\nTo calculate the brightness of an object shining with reflected light, the proper scaling factor is not a $1/r^2$ falloff as could be naively assumed. That is correct for an object radiating its own light; but not for one shining by reflected light; for that case the same $1/r^4$ scaling as in a radar return is appropriate.", "24" ], [ "That this is the correct scaling factor to use can be sanity checked based on the fact that despite being similar in size, Neptune is $\\sim 6x$ dimmer than Uranus despite being only $50\\%$ farther away: $1/r^4$ scaling gives a $5x$ dimmer factor vs $2.25$ for $1/r^2$.\nUsing that gives a dimming of 2400x at $210~\\textrm{AU}\\;.$ That puts us down $8.5$ magnitudes down from Neptune at perihelion or $16.5$ magnitude. $500~\\textrm{AU}$ gets us to $20$th magnitude, while a $2800~\\textrm{AU}$ aphelion dims reflected light down by nearly $20$ magnitudes to $28$ magnitude. That's equivalent to the faintest stars visible from an 8 meter telescope; making its non-discovery much less surprising.\nThis is something of a fuzzy boundary in both directions. Residual energy from formation/radioactive material in its core will be giving it some innate luminosity; at extreme distances this might be brighter than reflected light. I don't know how to estimate this. It's also possible that the extreme cold of the Oort Cloud may have frozen its atmosphere out. If that happened, its diameter would be much smaller and the reduction in reflecting surface could dim it another order of magnitude or two.\nNot knowing what sort of adjustment to make here, I'm going to assume the two factors cancel out completely and leave the original assumptions that it reflects as much light as Neptune and reflective light is the dominant source of illumination for the remainder of my calculations.\nFor reference, data from NASA's WISE experiment has ruled out a Saturn-sized body within $10,000~\\textrm{AU}$ of the sun.\nIt's also likely too faint to have been detected via proper motion; although if we can pin its orbit down tightly Hubble could confirm its motion.\nOrbital eccentricity can be calculated as:\n$$e = \\frac{r_\\textrm{max} - r_\\textrm{min}}{2a}$$\nPlugging in the numbers gives:\n$$e = \\frac{2800~\\textrm{AU} - 200~\\textrm{AU}}{2\\cdot 1500~\\textrm{AU}} = 0.867$$\nPlugging $200~\\textrm{AU}$ and $e = 0.867$ into a cometary orbit calculator gives a $58,000$ year orbit.", "70" ], [ "I'm following <PERSON> direction of thinking.\n1. Mars and Earth orbit the Sun. A single blow can't put Mars into path where it would gradually decrease its distance to Earth for 300 years.\n2. One could attempt to put Mars onto an eccentric orbit intersecting with Earth's orbit. That would require a knock of velocity of at last 2500 km/h (calculations below), thus quite some more than 21 km/h. Mars would then intersect the Earth's orbit in less than a year. Depending on the initial positions of the planets on their orbits the collision could occur during the first intersection or one of the further ones. If however they would not collide for 300 years, the Earth's orbit could be still perturbed by the gravitational force of Mars, which by itself could have catastrophic results. Predicting the details would require a complex simulation.\n3. If you want to postpone the collision for 300 years, I would propose to knock Mars away from the Sun, so it would cross Neptune's orbit and come back after 300 years to hit the Earth. One still would need to take into account possible interactions of Mars with the outer planets and perform very precise calculations, but that might be easier than keeping Mars just next to the Earth without a collision for 300 years. The knock velocity to the planet would need to exceed 11500 km/h so even more. An advantage of this method is that depending on the planets position the recoil may put the protagonist into virtually any spot in the solar system you want, including the Earth or its Moon.\n4. As the others pointed out, if the protagonist transfers momentum to the planet, it receives the same momentum in the opposite direction. For 2500 km/h knock on Mars a 100kg protagonist would receive energy of 16·10¹⁵ GeV per each nucleus of his body.", "921" ], [ "This is a lot. That's way more than any energy ever produced in laboratory or observed in nature. That's a hypothesized energy of Grand Unification (https://en.wikipedia.org/wiki/Grand_unification_energy). The act of knocking would be extremely violent. Complete disintegration of any molecular and nuclear structures, production of any known and perhaps unknown particles, maybe even black holes.\n5. Some suggested that the knock would destroy the planet. Maybe. The energy of the knock described in point 2 is 39·10³⁰ J, while Mars binding energy is perhaps 5·10³⁰ J. Some matter would follow in the desired direction. It's difficult for me to speculate how exactly it would turn out.\n6. Once the protagonist lands on another target planet or moon, it transfers its momentum to it, causing similar level of destruction and orbital perturbation as that done to Mars. As the others pointed out, it would violently interact with any matter on its way, and even with cosmic background (see: https://en.wikipedia.org/wiki/Greisen%E2%80%93Zatsepin%E2%80%93Kuzmin_limit).\nMaths. I'm sorry if there are any mistakes, but note we're in the regime where adding or deleting a zero wouldn't change the conclusions.\n1. Knocking Mars towards the Earth The total (potential and kinetic) energy of a planet with mass m orbiting around a star with mass M is $$E = -G\\frac{Mm}{2a},$$ where a is the semi-major axis.\nAssuming Mars following a circular orbit, $a=R_\\mathrm{Mars}$ (distance between Mars and the Sun), $$E_\\mathrm{Mars} = -187·10^{30} \\mathrm{J}.$$\nFor elliptic orbit between the present Mars and Earth's orbits $a = (R_\\mathrm{Mars} + R_\\mathrm{Earth})/2$, $$E_\\mathrm{Mars-Earth} = -226·10^{30} \\mathrm{J}. $$\nThe knock corresponds to change of the energy by $$\\Delta E = E_\\mathrm{Mars-Earth} - E_\\mathrm{Mars} = -39·10^{30} \\mathrm{J}.$$ As the potential energy remains constant, $\\Delta E$ corresponds to change of the kinetic energy only.\nThe orbital velocity of Mars is $v_\\mathrm{Mars} = 86430$ km/h, it's initial kinetic energy is $E_\\mathrm{k} = mv_\\mathrm{Mars}^{2}/2$, and final kinetic energy (just after the knock) is $$E_\\mathrm{k} + \\Delta{E} = m\\frac{(v_\\mathrm{Mars} + \\Delta v)^{2}}{2}.", "921" ], [ "This is an intriguing question, with a solution suggested by the <PERSON> et al. (2022; arXiv:2201.04516) paper that inspired the YouTube, NewScientist, ScienceAlert, Phys.org, etc. coverage of the past couple days. Still, I would wait a few years to see if others have alternate ideas before calling this case closed. Also, the paper needs to go through peer review.\nHere is the top half of Figure 1 from the <PERSON> et al. paper:\n\"Human eye\" curves are compared with Hubble Space Telescope spectra of the two planets. A couple things to note: Neptune is slightly more reflective where human blue optical cones peak, while Uranus is slightly more reflective where the red cones peak. So this is the color difference that the OP was asking and answering about. These Hubble observations of Uranus and Neptune were already published in 2009 and 2011 based on 2002 and 2003 observations.\nWhat is new from the <PERSON> et al.", "70" ], [ "study is a model, or theoretical description, of the haze and cloud layers present in both Uranus and Neptune. The paper actually argues for a simple structure of 3 haze/cloud layers on Uranus (plus one additional layer on Neptune), mostly similar between the two planets. Earlier papers assumed all the layers were either hazes (like photochemical smog) or ices (of methane or hydrogen sulfide), but this new model has hazes mixed into all the layers (except for that extra methane-cirrus layer on Neptune).\nThe \"Aerosol-2\" layer is the one claimed to account for color differences. In this new model, the Aerosol-2 layer is a little bit absorbing, especially at UV and blue wavelengths, which is a pretty standard assumption for haze layers. But it is located deeper in the atmosphere, where previous studies had called for a methane-ice condensation layer. Other scientists may use different haze/cloud models to describe Uranus and Neptune data. So it would be a good idea to wait and see whether the new <PERSON> et al. model gets challenged by others. Also it would be great to actually send probes to these planets and see whether any of these models are correct.\nIn the new <PERSON> et al. model, the main factors affecting the visible color of the two planets---the differences between the pink and black lines above---are more gaseous methane on Neptune (making Neptune less reflective than Uranus at red wavelengths), and more haze particles in one of Uranus' layers (making Uranus less reflective than Neptune at blue wavelengths).", "70" ], [ "Century\nFirst, you'd have to watch through a night to see if Polaris wobbles - currently, the radius is about 1° I think, but that changes with precession (and nutation, but that's small enough to ignore).\nOnce you know that, you can try to find a point in the sky that stays still all the time (like Polaris nearly does in our time). This is celestial pole, the direction the axis of earth points to.", "188" ], [ "It moves in a circle with ~23° radius ( = obliquity of the ecliptic, currenty ~23,4°). The center of the circle is roughly between Polaris and Vega, that makes it easy.\nThen, you have to see whether Polaris is approaching or departing it on its way on the \"precession circle\".\nIf you can measure the angle $\\alpha$ it has travelled on its way on this circle, you can estimate which century you have been transported to: $year = 2000 + \\alpha \\frac {26000} {360}$\nIf you take exact values and do all the calculations and especially the measurements very very exact, you might get more than just the century.\nIf you really want to prepare, print this and pin it somewhere you will see it every day: https://en.wikipedia.org/wiki/File:Precession_N.gif\nBeware that if you are transported more than 13,000 years back or forth, you will guess wrong.\nIn this case, you'll have to take the proper motion of the stars into account - you'll have to know not only the sky but also the motion of the stars (or at least a few) very very good. Which is the first thing that is really hard to do.\nMaybe you'd have to invent something with sticks for the measurements.\nYear\nI guess you need to know the planets positions (especially Jupiter because it's bright and not to fast) of the time you are transported to to derive the year - but you'd have to be a walking ephemeris for this.\nTime of the year\nThe time of the year is actually much easier than the year - most of the time, you can even feel it.\nIf you still need to calculate it, it is a direct function of the position of the sun in the sky:\nYou need to know the orientation of the ecliptic in the sky and the equinox of our time - in Pisces, you can see it in the image in that Wikipedia link: the intersection of \"0°\" and the ecliptic.\nYou measure the time in hours $h$ that passes from either the spring or the fall equinox (of our time) is at midheaven until the sun is at midheaven (noon).\nThe current date of the year, measured (roughly) from january to december in values from 0 to 1 is: $ y = h/24-0.2+\\frac \\alpha {360}$\nIf you took the fall equinox, you have to add or substract 0.5, whichever fits.\nWithout the $-0.2$, it would be measured from spring equinox (~ march 23rd) to spring equinox.\nGeographical latitude\nThe angle of the celestial pole mentioned above and the ground (as long as it's horizontal) helps you calculate the geographical latitude $ \\phi = 90°-angle$.\nGeographical longitude\nSorry, that's the thing I could not do.", "204" ], [ "It may or may not have rings\nRings are generally caused by an orbiting body breaking apart, either due to gravitational forces (e.i. the body gets to close to the parent planet, and is torn apart by tidal forces), or due to an orbital collision.\nNon of the factors you have specified make it impossible for rings to have formed. Rings are much more caused by what is orbiting the planet, rather than the parameters of the planet itself.\nHowever the stability of the rings, and how long they are likely to survive are determined by many other parameters. You have mentioned solar distance, and it is likely that if the (hypothetical) body which broke apart to create the (hypothetical) rings was predominantly icy, then much of the ice may have sublimated away, leaving thin rings. If the originating body was rocky or metallic, then a well developed ring system may still persist for long timescales.\nAnother key factor in the stability of the rings is the presence of other satellites with compatible orbital resonances. To simplify, orbital bodies will tend to pull and push each other over eons until they occupy nice ratios of orbital period (e.g.", "196" ], [ "with Jupiter, Io orbits roughly every 42 hours, Europa orbits about every 84 hours, and Ganymede orbits about every 168, creating a nice 1:2:4 ratio). The structure of rings would be expected to fit with orbital resonances of the planet's moons (for example, Saturn's rings have a large gap known as the Cassini Division, which matches a 2:1 resonance with Mimas). If new satellites were gained after the formation of the rings, they could disrupt them, and eventually lead to an altered ring structure, or even a dissolution of the rings. This would all depend on a great many factors, so there is no way to know.\nMuch of this is conjecture, as we are ultimately only able to observed the dynamics of ringed planets in our own solar system. It is possible that further effects (perhaps things like the <PERSON> effect?) may be more important for gas giants which orbit close to their parent star. Given that we do not yet have the ability to image rings around exo-planets, I do not believe astronomers can currently say for certain if all aspects of ring dynamics are fully known.", "196" ] ]

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[ [ "Let's first get some kind of definition of what resonance actually is. Wikipedia says the following:\nIn physics, resonance is a phenomenon that consists of a given system being driven by another vibrating system or by external forces to oscillate with greater amplitude at some preferential frequencies.\nEssentially, some amplitude becomes bigger at a certain frequency.\nnothing really addresses all types of systems in general\nThat's because it's not the primary goal of a physics text book to do this. If you want to understand systems in general, you will probably get more insight from a systems theory book.\nThey rather give examples of specific physical systems like LC circuits where electrical and magnetic fields are involved, or mechanical systems where springs and masses are.\nThat's because they can be described with the same differential equations, just using different symbols. You can substitute one for the other.\nA very important thing in systems theory is the transfer function, which is defined as \\$\\frac{output}{input}\\$ If you multiply this function with the input, you receive the output from the system. This function usually depends on the frequency.\nNow this sounds suspiciously related to the definition of resonance above.", "28" ], [ "If the transfer function has a value bigger than 1, the output (it's value or amplitude) will be bigger than the input. It's often the case that the transfer function has a maximum. In this maximum, the input is amplified the most, which is what's called the resonance.\nGiven a RLC row circuit as a system, one possible transfer function could be that of the overall voltage being the input and the voltage over the resistor being the output:\n$$\\frac{U_R}{U}=\\frac{R}{R+j\\omega L+\\frac{1}{j\\omega C}}$$\nAnother transfer function could be that of the overall voltage being the input and the current being the output:\n$$\\frac{I}{U}=\\frac{1}{R+j\\omega L+\\frac{1}{j\\omega C}}$$\nYou can see that both depend on $ \\omega =2\\pi f$. To show resonance, they have to have a maximum that's bigger than 1\nI'd say that resonance is not a property of the system per se, but a property of a pair of two of its properties, one being used as an input while the other is the output. If the transfer function, that describes the ratio between input and output has a maximum or peak at a certain frequency, then you have resonance.", "628" ], [ "I don't understand why do you ask this question and what exactly you are asking but here's my best effort.\nThe solutions to these reflections are found by imposing boundary conditions on the wave equations. Imagine a horizontal string and wave propagating to the right on it, which reflects off of a point. You can model all possible waves by a combination of sin and cos functions.\n$y_{incoming}(x,t) = Asin(x-vt) + Bcos(x-vt)$\n$y_{reflected}(x,t) = Csin(x+vt) + Dcos(x+vt)$\n(Change from -vt to +vt reflects the change in direction, and constants A, B, C, D determine the ratios of these terms to one another)\nIf we say that the string is glued to a point at x = 0, we will get the inversion you talked about. For this to be true, y(0,t) should be 0 at all times. So when you try to come up with an equation for the reflecting wave, you have to impose $y(0,t) = y_{incoming}(0,t) + y_{reflected}(0,t) = 0$ So that the string doesn't move at the connection point x=0.\n$y_{incoming}(0,t) = Asin(-vt) + Bcos(-vt)$\n$y_{reflected}(0,t) = Csin(-vt) + Dcos(-vt)$\n$y(0,t) = (A+C)sin(-vt) + (B+D)cos(-vt)$\nOnly if C = -A and D = -B, this formula will give 0 for all t values. Basically for any wave solution f(x-vt), the ideal reflection will be -f(x+vt).\nFor any kind of wave there is, there will be some value that propagates in time and space, pressure, displacement, electric field etc. So, they all can be modeled as \"value = f(x-vt)\". And when you impose that there is a point $x = x_0$, where the value is always 0, you'll see a similar result for all these kinds of waves.\nAs you may have realized, I have talked about what got inverted but not about what didn't.", "780" ], [ "That's because there is no need. Waves are basically disturbances of some value that will propagate in a medium as time passes. For example, the displacement for a sound wave which stayed untouched in your example was completely irrelevant in the first place. Sound is not about the displacement of the molecules which mostly stays stationary, it only involves pressure. The vertical displacement was the only value we kept track in our example so everything else stayed untouched, because they weren't involved in the process in the first place.\nYou may now say that this arguments completely gets crushed once we think about electromagnetic waves. But what's different about the electromagnetic waves is the boundary conditions you have to impose. Charges in a conductor will move around such that it has 0 net electric field on it (since any other configuration will cause the charges to move and therefore not a stable configuration). This means a conductor creates a boundary condition like our previous example. But the magnetic field has no such requirement and acts more like a freely connected string, which as you probably know will cause a reflection but not an inversion.", "395" ], [ "For circuit analysis, we don't really need fields. A simple one-dimensional description is perfectly sufficient.\nLet's first lock at the simple case of a battery connected to a (moderate) conductor. A conductor is a material where the electrons are \"loose enough\" so that they can move without too much force required.\nWhen the battery touches the ends of the conductor a force proportional to the voltage is applied to electrons and they start to accelerate. However, there is always friction inside the material (ignoring superconductors) so the electrons accelerate until the force of voltage and frictions balance each other. If they go any slower, the voltage will accelerate them and if they go any faster the friction will slow them down.\nFriction turns kinetic energy into heat and that's exactly where the energy goes. The friction of the electron flow generates heat. The amount of energy is a function of the \"electric friction\" (resistance), the driving force (voltage) and the amount of electron flow (current).", "395" ], [ "So we have\n$$P = VI = V^2/R = I^2R$$\nwhere $I$ is current, $V$ is Voltage , $R$ is the resistance, and $P$ is the dissipated power.\nNow let's look at a battery, two wires, and a light bulb. A \"wire\" is a conductor with a very, very low friction. Electrons can accelerate freely and nothing slows them down. Hence it's a REALLY BAD IDEA to put a wire across a batter since things tend to melt, explode, burn or do other nasty things.\nThe light bulb has a much higher resistance than the wires so the light bulb determines the speed limit for the electrons. All electrons go at the same speed since there are sitting \"one behind each other\" and the electrons in the wire can't go any faster. That means that almost all the energy is dissipated in the light bulb. The bulb and the wires see the same current but the resistance is vastly different since. If the resistance of the bulb is 1000 times higher than that of the wire, it will consume 99.9% of the entire energy.\nIn short: for regular resistive materials all the energy goes into heat that's generated by electrons bumping into things.", "395" ], [ "I think you are mixing two things: gradient and divergence.\nThe gradient is (normally) used when you have a scalar field, or function. A scalar field (or function) is when you associate a number to every point is space.\nThe divergence is (again, normally) used when you have a vector field, or function. A vector field (or function) is when you associate a vector (let's say x,y and z) to every point in space.\nThe magnetic field is a vector field, so you would normally just look at the divergence of that field. That being said, the vectorial gradient is something that exists, but is at a much higher level (http://math.stackexchange.com/questions/156880/gradient-of-a-vector-field).\nNow, if you meant \"what is the divergence of the magnetic field?\" The answer is 0, because it's always 0. This is actually an experimental truth and if you want to understand this, i'll refer you to this nice explanation: http://physics.stackexchange.com/questions/108224/why-is-the-divergence-of-a-magnetic-field-equal-to-zero\nEDIT: Thanks to @NeuroFuzzy for the pointer. So, to complement my answer, if by gradient you mean variation over a small distance of the magnetic field, then i'll compare three situations: 1. For an infinite wire (think of your power lines), the magnetic field will run around the wire following the right hand rule.", "499" ], [ "The intensity of the field will decrease following ~ 1/distance. In this case, you would say that the gradient is not very high because it doesn't vary a lot with distance.\n1. For a loop of current, the field at a distance from the center of the loop is a complicated equation. To get an intuitively pleasing result, you need to approximate how the field behaves at a good distance. This gives a field that derceases following ~ 1/distance^3, which means that it has a very strong gradient - it varies a lot.\n2. Lastly, my trick for visualizing a magnet is to think of it as a multitude of infinitely small current loops. Admitting this, and doing some (rather tough) math, you'll eventually find a formula (see eq. 8) which, for the same approximation as in case 2, give a variation of ~ 1/distance^3 again.\nSo, the final answer, would be to say that the gradient of your magnet is stronger than that of a power line - it varies more!\nHope it helps!", "395" ], [ "Let's take a look just from the point of view of someone reading the problem.\nFirst of all, we can say \"our car has motion\", because it's changing its position each second.\nOk. So, how is its motion? Well, it is moving in 1 dimention, it is a linear movement. Then, we can say \"our car has linear motion\". Also, we can see our car's velocity is changing every second. Then, we can say \"our car has linear motion, and has acceleration\".\nOk. So, how is its acceleration? Well, we can see from the chart that, in this particular case, it's velocity is changing constantly.", "562" ], [ "This is interesting and very important. To make a deduction from this, we need to remember how acceleration is defined:\nAcceleration is defined as the rate of change of velocity with respect to time.\nFor those of you with knowledge of calculus, you can take this definiton as:\nAcceleration is the second derivative of displacement.\nBut you don't need to know calculus to see that a constant change of velocity is equivalent to a constant acceleration.\nNow we can say \"our car has uniformly accelerated linear motion\" that also means \"our car has linear motion, and has a constant acceleration\".\nKnowing we have a constant acceleration, in order to understand what is going on, we only need 2 more things. Initial conditions, and the exact value of the acceleration.\nFor initial conditions you can see from the picture that at the start, time $t=0 s$, the car is where we call \"0 m\", or $x=0 m$. From the chart, we can read that the car has a velocity $v=0 m/s$.\nSo our initial conditions are: $$t=0 s$$ $$x=0 m$$ $$v=0 m/s$$\nAnd finally, we can see each that each second the velocity increases $10 m/s$. In other words, our acceleration $a$ must be $10 m/s^2$.\nNow that we have worked out the situation to the point we know everything from our problem, let's introduce your question.\nWhat should be the velocity of the car in $t=1s$?\nGoing back to our definitions, if the topic of your webpage is \"Meaning of Slope for a v-t graph\", you must be interested in how to find out the velocity at a certain step of time.\nThe graph of the v-t from your car is a straight line that goes from $(t=0,v=0)$ to $(t=5,v=50)$. The slope from this graph has the same meaning as the acceleration:\nThe slope is defined as the rate of change of the dependent variable (velocity) with respect to the independent variable (time).\nIf we call $m$ the slope from the graph, by definition it should be calculated:\n$$m = \\frac{\\Delta v}{\\Delta t} = \\frac{v_{j} - v_{i}}{t_{j} - t_{i}}$$\nGood for any integer $i,j\\leq 6$, as long as $i<j$.\nFor this particular case, and for any pair of data we choose, we will find:\n$$m = \\frac{1-0}{1-0} = \\frac{10}{1} = 10$$\nor, by definition of our variables:\n$$a = 10 m/s^2$$.", "234" ], [ "You have to choose a controller that best fits the system you are trying to control. You have to take into consideration the variables you are trying to control when deciding on the controller. Although the trajectory generator outputs four different values you don't have to use all of them.\nJudging from your question I assume you're trying to control the motion of something, maybe the movement of a robot arm or something similar, from position A to B. This has to happen in a smooth manner, which is why you have a trajectory. If this doesn't describe your system you will at least get a notion of how you can \"merge\" the trajectory outputs together.\nA simple controller that is easy to implement is the PID controller. It takes two of the trajectory outputs into account (position and velocity). Its controller law is expressed as\n$$u(t) = K_p \\cdot e(t) + K_i \\cdot \\int e(t) + K_d \\cdot \\dot{e}(t)$$\nwhere $u(t)$ is the input to the actuator, if you only have one actuator. The unit of $u(t)$ doesn't matter as you have to scale the PID parts anyway (see below).\n$e(t)$ is the error, and in this particular case defined as $e(t) = p_d - p$ (difference between desired position and actual measured position). Desired position is what you get from the trajectory.", "499" ], [ "That makes $\\dot{e} = v_d - v$. You get the desired velocity from the trajectory. You have to measure the velocity $v$. If you can't measure it you have to estimate it with a state observer. $\\int e(t)$ is the accumulated error over time.\n$K_p$, $K_i$ and $K_d$ are scaling factors (or gains). These are usually constants and have to be chosen by you using dimensional analysis and tuning on the real system. You choose the gains so that $u(t)$ looks reasonable with respect to magnitude.\nYou can expand the PID controller to include acceleration and jerk by adding additional parts to it. But as mentioned before, even though the trajectory outputs four parameters doesn't mean you have to use all of them, it just makes the motion smoother if implemented correctly. You could for instance choose to only use a P controller\n$$u(t) = K_p \\cdot e(t)$$\nI'm not going to write all the theory behind this controller here. You can read more on Wikipedia.", "499" ], [ "A quantity is dimensional if you can rescale it and all the relations remain the same. It is dimensionless if the numeric value has direct meaning in the equations.\nDistance is dimensional. Whether you use meters, feet or astronomical units, the relations with them stay the same, except related units, e.g. velocity, scale along with it. But angle is dimensionless. The value in radians is a ratio of lengths and if you use degrees instead, a conversion factor pops up in the relations. And bit is also dimensionless, being the 1 of information entropy, defined in terms of counts and probabilities.\nNow the dimensional quantities are still related to each other.", "432" ], [ "Since velocity is distance per time, if you scale the distance unit, the velocity unit scales with it.\nThe base units are a set that can be scaled independently of each other (in your problem domain!). Note that the choice is somewhat arbitrary. For example electric current was selected as base dimension, but electric charge would arguably make more sense. The other units are derived.\nThe problem domain is actually important. It turns out plenty of constants are actually just conversion factors due to choice of scaling. For example once special relativity gets involved, time becomes just another spatial dimension, distances can be measured in seconds, and velocity becomes a dimensionless ratio.\nIn fact, all the dimensional constants ones are and the natural units, especially in the planck variant, leave you with no dimensions at all and only the three dimensionless constants $\\pi$, $\\alpha$ and $\\alpha_G$.\nOn the other hand, there are cases where you can distinguish, say, parallel distance and perpendicular distance and then suddenly angle becomes perpendicular distance over parallel distance and is dimensional. If in what you do you don't mix the two, making them distinct units significantly improves utility of dimensional analysis as a verification.\nThe SI base units were simply chosen to be practical for classical physics and everyday engineering and is somewhat arbitrary (especially the candella, unit of luminous intensity, is not really a basic unit; it is just energy weighted-averaged over light spectrum using specific weighing function).", "432" ], [ "Why do higher frequencies tend to have a smaller amplitude than low frequencies?\nComplex waves found in nature tend to have downward sloping frequency distribution. This isn't to say the fundamental always has the highest level but the general trend is that higher overtones tend to have lower levels.\nThe simple answer is that energy is proportional to the square of frequency and square of amplitude and so increasing frequency must mean amplitude decreases, however that's assuming the energy of each mode is the same.\nOk so what about the equipartition theorem? When a system has multiple degrees of freedom, over time the energy will become evenly distributed among the modes. But this assumes the modes are coupled in a significant way. If we're talking about a superposition of sines like a plucked guitar string there should be very little coupling (an idealized string should have 0 coupling since the harmonics are orthogonal).\nHowever taken from here\nWhether the modes are orthogonal or not really only covers the question of whether they interact via linear processes, e.g. superposition. Orthogonal modes can still interact with each other nonlinearly, which is typically the case when one observes harmonics (assuming they are real harmonics and not spontaneously-excited modes that happen to be at twice the frequency of another mode). This most commonly takes the form of quadratic phase coupling, i.e. there are quadratic terms in the dependent variable in the governing equations.", "795" ], [ "That allows energy exchange between otherwise normal modes. While a guitar strings is likely pretty close to ideal for small amplitudes, it would be fairly unusual for a real-world problem with all the aforementioned complications to not include some degree of nonlinearity at higher amplitudes.\nThen there's the purely mathematical answer: the total energy of the vibration has to be finite. If we have an infinite number of possible modes of vibration you need some distribution of the energy between few of them and you get less and less energy left for higher ones (a la convergence).\nNow this isn't just for instruments, it also happens with electrical signals. I found this answer regarding electrical signals\nthe high frequency components in signals are by passed by the capacitive and inductive effects of the line. The value of these reactive components is such that they alter the higher frequencies more than the lower ones.\nNote: I'm not saying the that the lowest frequency has to be the loudest followed by the second harmonic, etc. A trumpet is a clear counter example to this. Just that the general trend is that the lower frequencies in a sound tend to dominate and the higher harmonics tend to decrease in amplitude the higher up you go.\nIn my searching I stumbled upon this\nA general answer is that most physical systems are low pass filters. They attenuate high frequencies more than low frequencies. There are exceptions, but most things are like that.\nThis makes sense for attenuation since attenuation is determined by the inverse of frequency but I'm talking about why higher frequencies aren't even excited to any significant degree in the first place\nEdit: I also came across this: \"Weighting harmonics proportionally to the square of the frequency is equivalent to differentiating twice and so gives a measure of the reciprocal of the radius of curvature of the wave-form and is therefore related to the sharpness of any corners on it\"\nof course the frequency spectrum of a wave is related to the shape of the wave but I think this might play a part in why we tend to not observe waves where the high frequencies have a high amplitude.", "795" ] ]

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