cahya/simple-wikipedia huggingface dataset:
Papaveraceae is a family of flowering plants. The family has been universally recognized by taxonomists, and is also known as the "poppy family". Most are herbaceous plants, but a few are shrubs and small trees.

Ranunculales
Myristicaceae is the botanical name for a family of flowering plants, mostly from Africa, Asia, Pacific islands, and the Americas. The family has been recognised by most taxonomists, and it is sometimes called the "nutmeg family", after its most famous member, the nutmeg (Myristica fragrans). It has about 21 genera and 520 species. They are mostly trees and shrubs.

References 

Magnoliales
The Dirac delta function, often written as , is a made-up concept by mathematician Paul Dirac. It is a really pointy and skinny function that pokes out a point along a wave. Loosely speaking, it has the value of zero everywhere except at , in such a way that the area between the function and the x-axis adds up to 1. The delta function is often used in sampling theory, where its pointiness is useful for getting clean samples.

The integral of the Dirac delta function is the Heaviside function. Thus Dirac delta function can be view as the derivative of Heaviside function.

Related pages 

 Special functions

References 

Digital signal processing
Newton's method provides a way for finding the real zeros of a function. This algorithm is sometimes called the Newton–Raphson method, named after Sir Isaac Newton and Joseph Raphson.

The method uses the derivative of the function in order to find its roots. An initial "guess value" for the location of the zero must be made. From this value, a new guess is calculated by this formula:

Here xn is the initial guess and xn+1 is the next guess. The function f (whose zero is being solved for) has the derivative f'.

By repeatedly applying this formula to the generated guesses (that is by setting the value of xn to the formula's output and recomputing), the value of the guesses will approach a zero of the function.

Newton's method can be explained graphically by looking at intersections of tangent lines with the x-axis. First, a line tangent to the f at xn is calculated. Next, the intersection between this tangent line and the x-axis is found. Finally, the x-position of this intersection is recorded as the next guess, xn+1.

Problems with Newton's Method 
Newton's method can find a solution quickly if the guess value begins sufficiently near the desired root. However, when the initial guess value is not close, and depending on the function, Newton's method may find the answer slowly or not at all.

Further reading
 Fernández, J. A. E., & Verón, M. Á. H. (2017). Newton’s method: An updated approach of Kantorovich’s theory. Birkhäuser.
 Peter Deuflhard, Newton Methods for Nonlinear Problems. Affine Invariance and Adaptive Algorithms, Second printed edition. Series Computational Mathematics 35, Springer (2006)
 Yamamoto, T. (2001). "Historical Developments in Convergence Analysis for Newton's and Newton-like Methods". In Brezinski, C.; Wuytack, L. (eds.). Numerical Analysis : Historical Developments in the 20th Century. North-Holland. pp. 241–263.

Related pages
 Kantorovich theorem (Statement about the convergence of Newton's method, found by Leonid Kantorovich)

Functions and mappings
Asimo was a robot that was built by Honda. The current models could walk, run, and go up and down stairs. Engineers planned to add laser capabilities. Its height was 130 centimeters (4 feet 3 inches) and weight 54 kilograms (119 pounds). Asimo was just like an astronaut wearing a backpack and could walk or run on two feet.

Development 
ASIMO was created at Honda's Research & Development Wako Fundamental Technical Research Center in Japan. Honda will not confirm how much it costs.

Name 
ASIMO is an acronym.  ASIMO stands for "Advanced Step in Innovative MObility". It should be pronounced “ah she moh” to match the original Japanese pronunciation.

As of February 2009, there are over 100 ASIMO units in existence.

Public appearances

ASIMO has made lots of public appearances.

Robots
Fahrenheit 451 is an American dystopian fiction novel. It was written by Ray Bradbury and first published in 1953.

The novel is about a future American society in which people are hedonistic (meaning they live only for pleasure), and reading is against the law because it makes them think. The main character, Guy Montag, has a job as a "fireman" (which, in this future, means "book burner"). The number "451" refers to the temperature (in Fahrenheit) at which the books burn when the "firemen" burn them "for the good of humanity". Written in the early years of the Cold War, the novel is a critique of what Bradbury saw as an increasingly dysfunctional American society.

The idea began with Bradbury's short story "Bright Phoenix," written in 1947 but first published in the Magazine of Fantasy and Science Fiction in 1963. The original short story was reworked into the novella, The Fireman, and published in the February 1951 issue of Galaxy Science Fiction. The novel was also serialized in the March, April, and May 1954 issues of Playboy magazine. Bradbury wrote the entire novel on a pay typewriter in the basement of UCLA's Powell library. His original idea in writing Fahrenheit 451 was to show his great love for books and libraries. He has often referred to Montag as an allusion to himself.

Over the years, the novel has been subject to various interpretations, primarily focusing on the historical role of book burning in suppressing dissenting ideas. Bradbury has said that the novel is not about censorship; he says that Fahrenheit 451 is a story about how television destroys interest in reading literature, which leads to people thinking that knowledge is made up of "factoids", partial information without context, such as Napoleon's birth date alone, without an indication of who he was.

A movie version of the novel was released in 1966, and at least two BBC Radio 4 dramatizations have also been aired, both of which follow the book very closely.

References 

1953 books
20th-century American novels
English-language novels
Fantasy books
Fiction set in the future
Hugo_Award_winners
Science fiction books
Collingwood School is a private school in West Vancouver, British Columbia, Canada. It teaches from Junior Kindergarten to Grade 12.

History

Collingwood School was opened in 1984 by West Vancouver and North Vancouver parents who wanted a private school nearby. The school was named after a ship called the HMCS Collingwood. The school used the buildings from the old Glenmore Elementary School. Now the school has buildings in two different parts of West Vancouver.

Facilities 

The "Morven" campus is the oldest part of the school. This is where they teach the older children, from Grade 6 to Grade 12. It is in a part of West Vancouver called the British Properties. The address is 70 Morven Drive, West Vancouver. The "Wentworth" campus was built later. This is where they teach the younger children, from Junior Kindergarten to Grade 5. It is right below Cypress Provincial Park in West Vancouver.

References

Other websites
Collingwood School Official Site
Round Square Official Site

Schools in Canada
1984 establishments in Canada
The stack is one of the most important data structures in computer science. To understand how a stack works, think of a deck of playing cards that is face down. We can only easily access the card that is on top. When we want to look at the top card, there are two things we can do: we can peek at it, but leave it on the stack, or we can pop it off. When we pop off the top object, we are taking it off the stack. If we want to add another card to the top of the stack, we push. 

A stack is called a last-in-first-out (LIFO) collection. This means that the last thing we added (pushed) is the first thing that gets pulled (popped) off. If the last card we put on our stack of cards was an ace, then the first card we pulled from the top is that same ace.

History 
The stack was first proposed in 1955, and then patented in 1957, by the German Friedrich L. Bauer. The same concept was developed independently, at around the same time, by the Australian Charles Leonard Hamblin.

Other operations 
In modern computer languages, the stack is usually implemented with more operations than just "push" and "pop". Some implementations have a function which returns the current length of the stack. Another typical helper operation is "top" (also known as "peek"), which can return the current top element of the stack without removing it. Another common operation is "dup," which makes a copy of the element at the top of the stack.

Related pages
 Stack machine

Computer science
Data structures
A nocturnal emission or wet dream is the condition in which a person has an orgasm while sleeping. It often leads to ejaculation. Wet dreams can begin after a person goes through puberty. Many young people have their first orgasm this way. They might not understand what has happened to them, if they have not been taught anything about sex.

Nocturnal emissions are called wet dreams in males because of the dampness caused by ejaculation and because the orgasm and ejaculation often happen during a sexually exciting dream. Scientists are not sure what causes them. Most sexual dreams do not cause orgasms.

It is harder for women to tell, because vaginal lubrication is not always associated with orgasm.

Wet dreams are natural and harmless. They do not mean that anything is wrong with you. Many people stop having wet dreams if they masturbate often, or once they begin having sexual intercourse on a regular basis.

If you urinate while asleep, this is called wetting the bed, not a wet dream.

Sleep
The Tevatron was a giant Particle accelerator in Illinois that was used by scientists to make protons go very fast, almost the speed of light in some cases. Scientists looked at what happens when the protons hit antiprotons to see if they are right about their ideas as to what protons are made of.

The Tevatron was a circular particle accelerator at the Fermi National Accelerator Laboratory (also known as Fermilab), just east of Batavia, Illinois. It was the second highest energy particle collider in the world after the Large Hadron Collider (LHC). The Tevatron is a synchrotron that accelerates protons and antiprotons in a 6.28 km (3.90 miles) ring to energies of up to 1 TeV, hence its name. The Tevatron was completed in 1983 at a cost of $120 million ($ today) and has been regularly upgraded since then. (The 'Energy Doubler', as it was known then, produced its first accelerated beam — 512 GeV —  on July 3, 1983.)  The Main Injector was the most substantial addition, built over five years from 1994 at a cost of $290 million.  The Tevatron was shut down on September 30, 2011.

The Large Hadron Collider was later built in Switzerland to look for one of those pieces, called the Higgs Boson. The LHC broke and is now being fixed. The Tevatron scientists also tried to find the Higgs Boson. They need to do this before the LHC is fixed, because the LHC is much better at finding things.

The scientists at the Tevatron had a year's headstart on the scientists at the LHC. Whoever finds the Higgs will be honored by other scientists. That is why the scientists at the Tevatron wanted to find it before the scientists at the LHC.

The Tevatron discovered three of the 17 fundamental particles including the top quark.  The main ring of the Tevatron will probably be reused in future experiments, and its components may be transferred to other particle accelerators.

References

Nuclear physics
Fermilab
The First Punic War started in 264 BC. It lasted for 23 years, ending in 241 BC. It was the first of three wars fought between ancient Carthage and the Roman Republic. They were rivals for trade and influence in the Mediterranean. For more than 20 years the two powers struggled for supremacy. Key areas were the island of Sicily and its surrounding waters, and also North Africa. Rome eventually won control of Sicily.

With the help of her own allies and rebels among the indigenous African allies of Carthage, Rome won the First Punic War after 23 years. In the end it became the dominant naval power of the Mediterranean. To get terms for peace, the Carthaginians had to pay a large amount of money (in silver), and give up a number of islands in the Mediterranean. They kept Sardinia and Corsica.

References 

264 BC
Punic Wars
Wars and battles of Ancient Rome
Scott Westerfeld (born May 5, 1963) is an American author of science fiction and young adult literature. One of his most famous book series was Uglies.

Books

Adults
Polymorph (1997)
Fine Prey (1998)
Evolution's Darling (2000)

Succession series 
 The Risen Empire (2003)
The Killing of Worlds (2003)
The two books were re-published in 2005 in one volume, also titled The Risen Empire.

Young adults 
So Yesterday (2004)
Afterworlds (2014)
Horizon (2017)

Midnighters trilogy
The Secret Hour (2004)
Touching Darkness (2005)
Blue Noon (2006)

Peeps series 
Peeps (2005) (also known as Parasite Positive in Britain and V-Virus or Peeps in Canada)
The Last Days (2006)

Uglies series
Uglies (2005)
Pretties (2005)
Specials (2006)
Extras (2007)
Impostors (2018)
Shatter City (2019)
Mirror's Edge (2021)
Youngbloods (2022)

Related works 
Bogus to Bubbly: An Insider's Guide to the World of Uglies (2008)
Graphic novel retellings from Shay's point of view:
Uglies: Shay's Story (with Devin Grayson and Steven Cummings) (2012)
Uglies: Cutters (with Devin Grayson and Steven Cummings) (2012)

Leviathan series (illustrated by Keith Thompson) 
Leviathan (October, 2009)
Behemoth (October, 2010)
Goliath (September, 2011)

Related works 
The Manual of Aeronautics (illustrated guide) (August, 2012)

Spill Zone graphic novel series (illustrated by Alex Puvilland) 
 Spill Zone (May, 2016)
 Spill Zone: The Broken Vow (July, 2019)

Related works 
 Spill Night (short story for Free Comic Book Day) (March 2017)

Zeroes trilogy (with Margo Lanagan and Deborah Biancotti)  
 Zeroes (2015)
 Swarm (2016)
 Nexus (2018)

References

Other websites

1963 births
Living people
Writers from Dallas, Texas
Partial Differential equations (abbreviated as PDEs) are a kind of mathematical equation. They are related to partial derivatives, in that obtaining an antiderivative of a partial derivative involves integration of partial differential equations.

Numerical methods

Since PDEs have appeared in mathematics and physics, many scientists have studied methods to solve them. But unfortunately, no one could establish methods to solve any kind of PDE. Therefore, numerical methods for PDEs (such as the finite element method) are widely studied since the appearance of computers.

Related pages
Differential equation
Functional analysis
Ordinary differential equation
Navier–Stokes equations

People who studied about partial differential equations

 Kyuya Masuda
 Peter Lax
 Ryogo Hirota
 Shinichi Oishi
 Sofya Kovalevskaya
 Terence Tao

Literature
 Partial Differential Equations (Graduate Studies in Mathematics) Lawrence C. Evans, American Mathematical Society, 2010/04/.
 Egorov, Y. V., & Shubin, M. A. (2013). Foundations of the classical theory of partial differential equations. Springer Science & Business Media.
 Olver, P. J., Introduction to partial differential equations. Berlin: Springer.
 Partial Differential Equations I-III (Applied Mathematical Sciences) Michael Taylor, Springer.

References

Mathematical analysis
Mathematical induction is a special way of proving a mathematical truth. It can be used to prove that something is true for all the natural numbers (or all positive numbers from a point onwards). The idea is that if:

 Something is true for the first case (base case); 
 Whenever that same thing is true for a case, it will be true for the next case (inductive case),

then
 That same thing is true for every case by induction.

In the careful language of mathematics, a proof by induction often proceeds as follows:
 State that the proof will be by induction over . ( is the induction variable.)
 Show that the statement is true when  is 1.
 Assume that the statement is true for any natural number . (This is called the induction step.)
 Show then that the statement is true for the next number, .

Because it is true for 1, then it is true for 1+1 (=2, by the induction step), then it is true for 2+1 (=3), then it is true for 3+1 (=4), and so on.

Examples of proof by induction

Sum of the first n natural numbers

Prove that for all natural numbers n:

Proof:

First, the statement can be written as:

    (for all natural numbers n)

By induction on n,

First, for n=1:
,

so this is true.

Next, assume that for some n=n0 the statement is true. That is,:

Then for n=n0+1:

can be rewritten as

Since 

Hence the proof is complete by induction.

The sum of the interior angles of a polygon
Mathematical induction is often stated with the starting value 0 (rather than 1). In fact, it will work just as well with a variety of starting values. Here is an example when the starting value is 3: "The sum of the interior angles of a -sided polygon is  degrees."

The initial starting value is 3, and the interior angles of a triangle is  degrees. 
Assume that the interior angles of a -sided polygon is  degrees. Add on a triangle which makes the figure a -sided polygon, and that increases the count of the angles by 180 degrees  degrees. Since both the base case and the inductive case are handled, the proof is now complete.

There are a great many mathematical objects for which proofs by mathematical induction works. The technical term is a well-ordered set.

Inductive definition

The same idea can work to define a set of objects, as well as to prove statements about that set of objects.

For example, we can define th degree cousin as follows:
A st degree cousin is the child of a parent's sibling.
A st degree cousin is the child of a parent's th degree cousin.

There is a set of axioms for the arithmetic of the natural numbers which is based on mathematical induction. This is called "Peano's Axioms". The undefined symbols are | and =.
The axioms are
| is a natural number.
 If  is a natural number, then  is a natural number.
If  then .

One can then define the operations of addition and multiplication and so on by mathematical induction. For example:

Related pages 
 Mathematical proof
 Proof by contradiction

References 

Mathematics
Hossein Sadjadi Ghaemmaghami Farahani (, better known by his pen name Kader Abdolah () (Arak, 12 November 1954), is a Dutch author who was born in Iran.

Kader Abdolah was born Hossein Sadjadi Ghaemmaghami Farahani () in Arak, Iran. Since 1988 he has been living in the Netherlands.

His books are often written in Dutch.  He adds ideas from Persian literature.  He wrote "De reis van de lege flessen", "The journey of the empty bottles".  The book is about an Iranian who goes to live in the Netherlands.  "The House of the Mosque" was voted second best Dutch novel ever in Holland. "My Father's Notebook: A Novel of Iran" and "The House of the Mosque" are available in English.

Honours and awards
 Knight in the Order of the Netherlands Lion
 Knight in the French Order of Arts and Literature

References

Other websites

1954 births
Living people
Iranian writers
Naturalised citizens of the Netherlands
Dutch columnists
Dutch novelists
Persian people
Pseudonyms
Wigan is a town located within the Metropolitan Borough of Wigan in Greater Manchester, North West England. It is home to Wigan Athletic football club and Wigan Warriors rugby league team. It is about twenty miles from Liverpool, Manchester and Preston.

Wigan
Towns in Greater Manchester
Polymerization or polymerisation is the process in which small molecules, called monomers, join chemically to produce a very large chain-like or network molecules, called a polymer. The monomer molecules may all be alike, or they may represent two, three, or more different compounds. Usually at least 100 monomer molecules must be combined to make a product that has certain unique physical properties—such as elasticity, high tensile strength, or the ability to form fibres—that differentiate polymers from substances composed of smaller and simpler molecules. Often, many thousands of monomer units are incorporated in a single molecule of a polymer. The formation of stable covalent chemical bonds between the monomers sets polymerization apart from other processes, such as crystallization, in which large numbers of molecules aggregate under the influence of weak intermolecular forces.
Alkene molecules can react with themselves, by adding polymerization to form 'plastic' or polymeric materials. When a catalyst (a substance that speeds up chemical processes) is added to the reaction, or it is heated under pressure, unsaturated alkenes link together, when the double bond partially breaks.

Uses of polymers: Polyethene- it is a cheap and useful plastic used for plastic bags and bottles, it is also very flexible and quite strong.

Polymer chemistry
This article is about the town. For the band with the same name, see Portishead (band).

Portishead is a town near the sea in North Somerset, England, where about 21000 people live (Local council update July 24, 2007).

Portishead has had a history since Roman times. Its name comes from the words ‘port at the head of the river’.  The town was built on the mouth of a small river; the main road in the town once met the water at the top of the river.

Lots of buildings in the town are of a Victorian style.

Portishead's dock and railway lines

Portishead dock

In the 1860s, in the middle of the iron and steel era, a pier and a dock were built for the big boats that could not easily get to Bristol Harbour. The ships brought in expensive items from around the world and took items made in the town to other countries. Many ships carried coal.

In the 1880s Portishead Dock was bought by Bristol Corporation, and was managed as part of the Port of Bristol until it closed.

Portishead power stations
The Portishead power stations were coal power stations built near the dock. The first power station was built in 1926. It began making electricity in 1929 for the Bristol Corporation. The power station was made bigger in 1948.

A 2nd power station was started in 1949 and began making electricity in 1955.

After 1949, the power stations became part of the country's electricity industry. They used some local coal produced in the Somerset coalfield which was moved by train along the Portishead Railway. The line had opened on 12 April 1867 as the Bristol and Portishead Pier and Railway Company; it opened to the dock on 5 July 1879.

The 1st power station closed in 1976, and the 2nd closed in 1982. The dock was closed in 1992.

Railway stations
Portishead had two train stations for people who lived in the town. The main station was near the centre of Portishead, and the other was at the Pier. The construction of the 2nd power station caused the 1st train station to be removed and another station was opened in the main street of the town on 2 January 1954. The new station closed on 7 September 1964. People who live in Portishead now want the train station to be opened again.

References

Further reading
 Awdry, Christopher, (1990). Encyclopaedia of British Railway Companies. London: Guild Publishing.
 Crowhurst, Ken, (2001). Images of England: Portishead, Stroud: Tempus Publishing. .
 Smith, Martin, (1992).  The Railways of Bristol & Somerset, Sherton: Ian Allan Ltd. .
 Winter, Michael T., (2005). The Portishead Coal Boats: A History of Osborn & Wallis Ltd, Bristol. Lydney: Black Dwarf Publications. .

Other websites

 
 Weston, Clevedon & Portishead Railway
 Portishead and Bristol Lifeboat
 Photos of Portishead in 3d (Anaglyphs) 

Towns in Somerset
Adverse possession is a rule in property law. This rule says that if property is not being used by its owner while another person is using the property, this other person (called an "adverse possessor") becomes the new owner of the property. To get these rights, the adverse possessor usually must use the property in the way a normal owner would do for a period of time, typically 20 years. In some jurisdictions, a form of adverse possession exists in which the adverse possessor ends up with sharing some rights to property with the owner, such as a right-of-way, instead of getting all the rights.

Legal terms
Property
The Rule against Perpetuities is one of the most complicated rules in property law and wills and trusts.  In general, the rule states that a gift of a will (or a trust) will not be enforced if the subject of the gift is to be given to a person who can not be known now, and will not be able to be known, by the end of 21 years after the death of everyone who was alive (including children in their mother's uterus but not yet born) at the time the gift was created.  

For example, if a woman says in her will that her house is to be given "to the children of her children when they graduate from college" this would not be enforced by a court. It would not be enforced because one (or more) of her children's children might not graduate from college until 21 years after everyone who was alive at the time of the woman's death has died.  

The purpose of the rule is to prevent property from being tied up for "perpetuity" (a very long time).  The courts (and many people in society) do not want to hold property to see who will receive it after a complicated set of rules from the gift-giver. First, this would result in a waste of the courts' time and resources. Second, it would be a waste of the property that is being given through the gift.  If a gift in a will violates the Rule against Perpetuities, the court will simply strike that gift and transfer the subject of the gift as if the will had not mentioned it.

However, many countries and states have changed this rule, and it does not apply at all, or in a changed way, in those countries and states.

Property
A polypeptide is a string or linear chain of amino acids linked together. Amino acids are the basic building blocks of proteins.  A single polypeptide chain might make up the entire primary structure of a simple protein; more complex proteins are formed when two or more polypeptides link together. Each protein is a polymer of amino acids.

Polypeptides are made when mRNA is translated, a process involving ribosomes, tRNA and amino acids.

References

Biochemistry
Solipsism ( ) is the view that a person has no reason to believe anything exists except their own mind. It is a philosophical position that first appeared in ancient philosophy. It mainly means to reject or doubt that other people exist. "" and "" are the Latin words for "alone" and "self", which is where the word "solipsism" comes from. Some kinds of solipsism say that everything outside a person's own mind (including other people) is only imaginary. Other kinds of solipsism instead say that nothing outside a person's own mind is certain.

To only reject that the physical world exists is not solipsism. Solipsism also rejects or doubts that other people exist. As an epistemological position, it is the concept that nothing but one's own mind can be certain to exist. The existence of other minds, in this position, is considered a possibility, but not a certainty. Including time, which does not stop just because there would be nobody being to experience it (which is probably going to happen in the end of the universe when there would be simply nothing)

Related pages 
 Egoism
 Idealism
 Nihilism

References 

Epistemology
Philosophical movements and positions
A dipstick is a tool which can be dipped into liquid to measure how much of it there is, or to test it for things.

Testing dipstick 
A testing dipstick is usually made of paper or cardboard. It contains substances which change colour when something is found in a liquid.

Measuring dipstick 

 
Measuring dipsticks show the amount of liquid in a container. These containers are usually hard to access. Measuring dipsticks are used by inserting and removing the stick and then checking how much of the stick is covered by the liquid. The oil level dipstick is an example of a measuring dipstick found on most internal combustion engines.

Science
Engineering
Tools
An elliptic curve is a plane curve of degree 3 that can be described using the following formula:

,

where  and  are integers.

Geometry
The Northrop Grumman B-2 Spirit, also called the Stealth Bomber, is an American strategic bomber. It has a lot of stealth technology, and it is designed to get through many anti-aircraft defenses. It can drop both conventional and nuclear weapons. Two people fly the bomber, and it can drop up to 80 -class JDAM GPS-guided bombs, or sixteen  B83 nuclear bombs. 

The bomber began being designed as the "Advanced Technology Bomber" (ATB) during the Carter administration. The designing of the ATB continued during the Reagan administration. The bomber was designed and is made by Northrop Grumman, with help from Boeing. Each aircraft cost US$737 million (in 1997 dollars). 

Because the bomber is very expensive, the project was controversial in the U.S. Congress. The end of the Cold War meant that the bomber was not really needed anymore. Congress wanted to buy 132 bombers, but during the late 1980s and 1990s, Congress reduced this to 21. In 2008, a B-2 was destroyed in a crash shortly after takeoff. The crew got out safely. 20 B-2s are being used by the United States Air Force. 

Although the B-2 was supposed to be a mainly nuclear bomber, it was first used in combat to drop normal bombs on Serbia during the Kosovo War in 1999. It was used during the Iraq War and it is being used in the war in Afghanistan.

References

Other websites 

 B-2 Spirit fact sheet and gallery on U.S. Air Force site 
 B-2 Spirit page on Northrop Grumman site 
 B-2 Spirit Stealth bomber on airforce-technology.com
 B-2 Stealth Bomber article on How It Works Daily
 B-2 Spirit page at GlobalSecurity.org

United States Air Force aircraft
Diapause is a delay in development which has evolved in response to regular periods of adverse environmental conditions.

It is a physiological state with very specific conditions. Diapause is a mechanism used as a means to survive predictable, unfavourable environmental conditions, such as temperature extremes, drought or reduced food availability. It is most often observed in arthropods, especially insects, and in the embryos of many of the oviparous species of fish in the order Cyprinodontiformes.

Not only is diapause started by specific stimuli or conditions, but once it is started, only certain other stimuli are capable of bringing the organism out of diapause. This distinguishes diapause from other forms of dormancy such as hibernation.

Activity levels of diapausing stages can vary considerably among species. Diapause may occur in a completely immobile stage, such as the pupae and eggs, or it may occur in very active stages that undergo extensive migrations, such as the adult Monarch butterfly, Danaus plexippus. In cases where the insect remains active, feeding is reduced and reproductive development is slowed or halted.

References 

Physiology
An electric field is a vector field that shows the direction that a positively charged particle will move when placed in the field. More precisely, if a particle has an electric charge  and is in an electric field , the electric force the charge will feel is  .Electric fields are produced around objects that have electrical charge, or by a magnetic field that changes with time. Electric field lines are used to represent the influence of electric field.  The idea of an electric field was first made by Michael Faraday.

Electric fields are caused by electric charges, described by Gauss's law, or varying magnetic fields, described by Faraday's law of induction.  The equations of both fields are coupled and together form Maxwell's equations that describe both fields as a function of charges and currents.

References 

Electromagnetism
A potato gun or Potato cannon is a type of cannon that uses combustion or air pressure to fire a projectile. They are called potato guns because potatoes are a commonly used projectile.

There are two main types of potato guns. Combustion guns use a flammable fuel and igniter to move an object. Another type uses compressed air. Potato guns are usually built of PVC or ABS (a type of plastic) piping.

Combustion potato guns

Parts
Combustion potato guns have 4 parts. These are the barrel, combustion chamber, a cap, and an igniter.
Barrel: The barrel is the part of the gun which the projectile is fired from. It is usually a smaller diameter than the combustion chamber.
Combustion chamber: This is the part where the fuel is put. The igniter is also in the combustion chamber.
Igniter - A device which set the flammable fuel on fire. Electric grill igniters and magnesium latern lighters are often used. This could be called a trigger.
Cap - The cap is connected to the combustion chamber. It is removed to add fuel and replaced when the gun is fired.

Operation
the operator will put a projectile into the barrel. A ramrod is often used to push it all the way down to the end of the barrel. The projectile must fit tightly into the barrel so that the pressure of the expoding fuel is strong enough to move it. This is why potatoes are often used. With a large potato, the unneeded part of potato would be cut off when the potato is forced into the barrel. This creates a projectile that is almost the exact size as the inside of the barrel.
The cap is removed and a flammable fuel is put in the combustion chamber. Aerosol hairspray is a popular fuel because it ignites easily. Once fuel is added, the cap is replaced.
The cannon is pointed at its target and the igniter triggered. This causes the fuel to burn. The rapidly expanding gasses force the projectile out of the end of the barrel.

A potato cannon can move a 2" diameter potato projectile over 100 yards at a speed of 40 mph. This makes potato guns dangerous.

Air powered potato guns

Parts
 A source of compressed air (such as air compressor) 
 Barrel: 
 Air reservoir - This is where compressed air is held before being released. It serves the same job as the combustion chamber in the other version.
Release - a type of valve. It is placed between the air reservoir and the barrel. This could be called a trigger.

Operation
the operator will put a projectile into the barrel. A ramrod is often used to push it all the way down to the end of the barrel. The projectile must fit tightly into the barrel so that the pressure of the air is strong enough to move it.
The air reservoir is filled by connecting it to a compressed air source. The release be closed at this time.
the cannon is aimed and the release is pulled. This causes the compressed air to rush into the barrel. The high pressure forces the projectile out of the end of the barrel.

A air powered potato cannon is much stronger than a combustion cannon. A combustion potato gun will launch projectiles at a pressure of about 10-20 psi. Air powered guns often use pressures over 100 psi.

Other websites 
Instructables.com
Howstuffworks.com

Weapons
A parsec is a unit of distance used in astronomy. It is the distance that light travels in 3.26 years, or just under 31 trillion kilometres (about 19 trillion miles). This is from the definition: a parsec is the distance from the Sun to an object which has a parallax angle of one arcsecond.

Distances measured in fractions of a parsec usually involve objects within the same star system. 

Surveying provides an everyday example of parallax. Go outside and look at a distant object. Hold your hand out with one finger raised and close one eye. Line up your finger so it covers the object from view. Then close that eye and open the other without moving your arm. Now, move your finger to block that eye's line of sight. The two positions your finger was at  can be used to find the distance from the object. This is what a survey crew does to figure out land plot boundaries. The mathematical technique used in the calculation is trigonometry. A parsec is so large that if you could see that far that you would be looking in to the past. You are looking 3.26 years in the past because it takes 3.26 years for the light to come from a parsec away.

Astronomical distances
Units of length
Puget Sound is a sound in Western Washington. It is a large area of salt water that is partially cut off from the rest of the Pacific Ocean. Many of Washington's cities, like Seattle and Tacoma are next to the sound. Many boats travel on the sound. Some of the boats are Ferries which take people from the main part of Washington to the islands in the sound. Many boats come from across the ocean from places like Japan, and China to trade in Washington.

Geography of Seattle, Washington
Bodies of water of the United States
The Legacy of Heorot is a science fiction novel written in 1987 by Larry Niven, Jerry Pournelle and Steven Barnes.

This is the first book in the Heorot series. It is about a human space colony at the star Tau Ceti.

Plot Summary 

Hundreds of years in the future, people travel to the star Tau Ceti. It takes 100 years to fly there. To live that long the people go to sleep and freeze each other. When they get there they unfreeze, but some people do not wake up. Some people wake up but are not as smart as they were.

They land on the fourth planet from the sun and build a town on a big island. Everything is peaceful until they are attacked by a large animal. The animal is like a cross between a frog and an alligator. It is big but also very fast and smart. They call it a Grendel. The Grendel kills several people but then it is killed.

The people get very scared and build fences, land mines, and guns. After a while they get less scared and think that the Grendel they killed was the only one. They build boats and get brave. Then another bigger Grendel kills some of the people in the boats. The People trap and kill this Grendel.

The People get really mad. They find out that Grendels have to stay near water because when a Grendel moves fast it makes a lot of heat. If it does not cool off it will die. They go all around the island and kill all the Grendels. This makes them very happy.

They feel safe and travel all around the island. They notice that the alien fish are big now. They think that without the Grendels around there will be lots of fish to eat. This makes them happy.

Everything is good until the fish get very big. When they get big enough they grow legs, breath air, and move very fast. The fish are baby Grendels. Now instead of a few big Grendels there are thousands of small ones.

Some people escape to the space ship. But, other stay to defend the town. They use the electric fences and land mines and guns to kill the little Grendels. After awhile the town gets too damaged to protect anymore. The people run away to a cave on a mountain. The Grendels follow them up a river and attack the cave. The people use kerosene to burn the Grendels. Also, they knock big rocks down onto them. After enough Grendels get killed, the other Grendels learn to run away instead of just attack. The people win.

Over time the people hunt down all the new Grendels and all the alien fish. Finally they are safe.

1987 books
Science fiction books
Horror novels
xkcd is a comic strip on the Internet. American cartoonist Randall Munroe draws and writes the comic. The comic is drawn in boxes. It is one of the most popular comics on the Internet. It is "a webcomic of romance, sarcasm, math and language". Sometimes, the readers of the comic act out things that Munroe puts in his comics. There are also messages in all comics that show up when moused over. In October 2007, the comic was viewed about 60 million times. The comic has won many awards. The name "xkcd" does not mean anything and was just made so people do not say it as a word.  there are more than 2400 different xkcd comics.

In November 2015, Munroe wrote a book named Thing Explainer,  using the same stick figure drawings from his comic. The book is about how things work, and is written in Simple English. It uses only one thousand different simple words. The idea for it came from a comic "Up goer Five" which is about the Saturn V rocket.

References 

Notes

Other websites 
 Main site
 A site for explaining the comics of xkcd

Webcomics
Lamar Advertising is an outdoor advertising company. The company was founded in the year 1902. The company's headquarters is in Baton Rouge, Louisiana. Lamar operates in the United States of America, Canada and Puerto Rico. They sell advertising on billboards. They sell advertising on buses. They have digital billboards.

Departments 
Lamar has many parts called "departments". This is common in most companies. Here are some parts of Lamar.
 IT (it stands for Information Technology)
 Human Resources
 National Sales
 Plants (this is what Lamar calls its offices)

Other websites 
 Lamar

1902 establishments in the United States
Baton Rouge, Louisiana
Companies based in Louisiana
Advertising companies
Joshua Winslow "Josh" Groban (born February 27, 1981) is an American singer, songwriter, musician, actor, and record producer. He has won awards.

Early life
Groban was born in Los Angeles, California. His parents are Lindy (nee Johnston), a school teacher, and Jack Groban, a businessman. He has a younger brother, Chris, who shares the same birthday, but four years younger. Groban's father was born Jewish, and is a descendant of Russian and Polish immigrants; he converted from Judaism to Christianity when marrying Groban's mother. Groban's mother's ancestry includes Norwegian (from Toten), German, and English; one of her own grandfathers had been Jewish. Groban's parents are Episcopalians.

Groban debuted as a singer in the seventh grade.

References

1981 births
Living people
American songwriters
American musicians
Singers from Los Angeles
Grammy Award winners
A network bridge is a device which connects two parts of a network together at the data link layer (layer 2 of the OSI model). 

Network bridges work similarly to network switches, but the traffic is managed differently. A bridge will only send traffic from one side to the other if it is going to a destination on the other side. This is different to a layer 1 switch which sends all traffic from either side. Sometimes network bridges are called layer 2 switches. 

Since they need to look at the contents of the traffic going into them, they are much more complicated than a hub or repeater.

How is it different to a switch? 
Network Switches and Bridges are both Layer 2 devices. They  operate at the Data Link Layer (Layer 2) of the OSI Reference Model. Network Switches and Bridges have many similarities and similar  function. But Switches are considered as superior devices than bridges.

Following are the major differences between  network switches and bridges.

• Packet forwarding in Bridges are performed using software. Packet forwarding in Switches are performed using ASICs (Application Specific Integrated Circuits).

• Switches operate comparatively higher speeds that Bridges.

• Method of switching of a Bridge is store and forward. Method  of switching of a Switch can be store and forward, cut-through or fragment-free.

• Normally a Switch has more ports than a Bridge.

• Bridges can operate only in half duplex mode, but a Switch can operate both in half duplex or full duplex mode.

• Both Bridge and Switch has one collision domain per port, but switches have one broadcast domain per VLAN.

• Switches support full-duplex Local Area Network (LAN) communication.

Related pages
 Shortest Path Bridging

Computer networking
The Great Northern War (1700–1721), was a war fought between Sweden and the coalition of Russia, Saxony, Poland, and Denmark-Norway. In 1715 Prussia and Hannover joined the war against Sweden. The King of Hannover was also King George II of Great Britain.

After the coalition attacked them, Sweden invaded Russia in 1709 which was not a good idea. The Russian Army retreated  so the Swedish Army had to chase them. When winter came it was the coldest winter that Europe had had in a hundred years and half of the Swedish soldiers died in the cold. Eventually the Swedish army caught up to the Russian army and they had a battle, called the battle of Poltava. Russia won the battle but most of the Swedish soldiers, including king Charles XII of Sweden, escaped and went to the Ottoman Empire. Peter, the king of Russia, didn't like this so he declared war on the Ottoman Empire.  He lost and had to give the town of Azov back to the Ottomans.

Charles XII left the Ottoman Empire in 1714 and went to Stralsund in Pomerania which was owned by Sweden at the time but was under siege.  Charles escaped back to Sweden just before the people in Stralsund surrendered. Then he invaded Norway (which was owned by Denmark at the time.) and was shot and killed there. With their king gone, the Swedish soldiers left Norway and went back to Sweden. On the way back many soldiers died.

When all that was happening Russia had been invading Sweden. Russia conquered  Estonia, Livonia and Ingria. By the time the remaining soldiers had come back from Norway, Russia had completely conquered Finland. Sweden still didn't want peace though, because they would have to give lots of land to Russia. Russia used a newly made fleet of ships to attack and raid the Swedish Coast and Sweden would still not give up.  Eventually the Russian and Swedish ships came together in the Battle of Grengam. Both sides thought they had won the battle so no treaty was signed until the Russians continued using their boats to damage the Swedish coast. Finally Sweden gave up in 1721. Sweden had made peace with Denmark in 1720 and in 1721 Sweden signed the treaty of Nystad.

Treaties 
In the Treaty of Nystad Sweden had to give land to other countries. Sweden had to give Estonia, Livonia and Ingria to Russia but could keep Finland. Sweden also signed other treaties. These were the treaty of Stockholm where Sweden gave Prussia Swedish Pomerania and the treaty of Fredericksborg where Sweden had to pay Denmark-Norway money for the damage the war had done.

This war was significant because it allowed Russia to become the dominant power in Northeastern Europe, instead of Sweden.

Wars involving Russia
CentOS is a distribution (or distro) of Linux that is made to be similar to Red Hat. It was first made because the company that made Red Hat stopped making it free. Now, many people work on CentOS, and many more people use it on their computers. Often, CentOS is used on servers (computers which provide services to people or other computers) because it is stable (does not break often) and can be installed (put on a computer) in not much time, compared to other distributions such as Gentoo. On December 8th 2020, The CentOS Project announced the end of CentOS as it was previously known and announced CentOS Stream. AlmaLinux among others now provide 1:1 binary compatible releases with RHEL and the original CentOS. The original CentOS will reach end of life December 2021.

Other websites 
 Official website

Linux distributions
David Jon Gilmour CBE (born 6 March 1946) is an English musician, record producer, songwriter. He is most famous for being a guitarist, singer and songwriter in the rock band Pink Floyd. Along with being in Pink Floyd, he has worked as a record producer for other musicians. Gilmour has also recorded and released albums as a solo performer.

Gilmour has always been active with many different charities. He was appointed CBE in 2003 for services to both music and for his charity work.

In 1996, Gilmour was inducted into the Rock and Roll Hall of Fame as a member of Pink Floyd.

In 2003, Gilmour was listed at number 82 in Rolling Stone Magazine's list of the "100 Greatest Guitarists of All Time" 

 Discography 
 David Gilmour (1978)
 About Face (1984)
 On an Island (2006)
 Live in Gdańsk (2008)
 Rattle That Lock (2015)
 Live at Pompeii'' (2017)

Notes 

1946 births
Living people
Commanders of the Order of the British Empire
English guitarists
English rock musicians
English singer-songwriters
Musicians from Cambridge
Pink Floyd