OpenLLM-France/wikimedia huggingface dataset:
# Organic Chemistry/Introduction to reactions/Gibbs free energy

<< Acids and bases |
Gibbs free energy is represented by the following equation:
    ΔG = ΔH -TΔS
    ΔG is the change in Gibbs free energy.
    ΔH is the change in potential energy, sometimes known as the enthalpy of a system.
    T is the temperature in Kelvin.
    ΔS is a statistical correlation, known as the entropy of a system.
The basic principle is that total entropy increases. This increase can be because of an increase in the entropy of the chemicals, ΔS, or because the reaction has produced heat, increasing the entropy of the environment.
The Gibbs free energy lets us calculate the total increase in entropy, including the effects on the environment, without needing to know anything about the environment.
At low temperatures, ΔG is approximately ΔH, and nature favours the reaction with lowest energy products, which release the most heat. This may reduce the entropy of the system, but the increase in the entropy of the environment more than compensates.
At high temperatures, ΔG is approximately -TΔS, and nature favours the reaction with high energy products, which may actually absorb heat. This may reduce the entropy of the environment, but the increase in the entropy of the system more than compensates.
Either way, the Gibbs free energy always decreases.
<< Foundational concepts | << Acids and bases | Gibbs free energy | Alkanes >>
# Linux Networking/IP Firewall (for Linux-2.2)
## IP Firewall (for Linux-2.2)

The new firewalling code is accessed via IP Firewalling Chains. See the ipchains home page for more information. Among other things, you'll now need to use ipchains instead of ipfwadm to configure your filters. (From Documentation/Changes in the latest kernel sources). We are aware that this is a sorely out of date statement and we are currently working on getting this section more current. You can expect a newer version in August 1999.
# Linux Networking/IP Masquerade
## IP Masquerade

Many people have a simple dialup account to connect to the Internet. Nearly everybody using this sort of configuration is allocated a single IP address by the Internet Service Provider. This is normally enough to allow only one host full access to the network. IP Masquerade is a clever trick that enables you to have many machines make use of that one IP address, by causing the other hosts to look like, hence the term masquerade, the machine supporting the dialup connection. There is a small caveat and that is that the masquerade function nearly always works only in one direction, that is the masqueraded hosts can make calls out, but they cannot accept or receive network connections from remote hosts. This means that some network services do not work such as talk and others such as ftp must be configured to operate in passive (PASV) mode to operate. Fortunately the most common network services such as telnet, World Wide Web and irc do work just fine.
Kernel Compile Options:
Normally you have your linux machine supporting a slip or PPP dialup line just as it would if it were a standalone machine. Additionally it would have another network device configured, perhaps an ethernet, configured with one of the reserved network addresses. The hosts to be masqueraded would be on this second network. Each of these hosts would have the IP address of the ethernet port of the linux machine set as their default gateway or router.
A typical configuration might look something like this:
Masquerading with IPFWADM
The most relevant commands for this configuration are:
Masquerading with IPCHAINS
This is similar to using IPFWADM but the command structure has changed:
You can get more information on the Linux IP Masquerade feature from the IP Masquerade Resource Page. Also, a very detailed document about masquesrading is the ``IP-Masquerade mini-HOWTO (which also instructs to configure other OS's to run with a Linux masquerade server).
# Linux Networking/IPv6

Just when you thought you were beginning to understand IP networking the rules get changed! IPv6 is the shorthand notation for version 6 of the Internet Protocol. The main driver of the design of IPv6, was the IPv4 address exhaustion. Also the number of devices that require IP addressing has grown, especially mobile devices with the explosion of the "mobile Internet". It is expected that in future there will be much more connected devices (with new trends in home automation and connectivity in cars). IPv6 addresses are 16 bytes long (128 bits). IPv6 incorporates a number of other changes, mostly simplifications, that will make IPv6 networks more manageable than IPv4 networks.
Linux already has a working, but not complete, IPv6 implementation in the 2.2.* series kernels.
The IPv6 addresses are normally written as eight groups of four hexadecimal digits, where each group is separated by a colon (:).
Syntax: XXXX: XXXX: XXXX: XXXX: XXXX: XXXX: XXXX: XXXX
For example: 2001:0 DB8: 85A3: 08D3: 1319:8 A2E: 0370:7334

## Main Features

* Larger address space
* Address scopes
* Stateless address configuration
* Multicast
* Mandatory network layer security
* Simplified processing by routers

## DHCPv6

DHCPv6 is a protocol for dynamic host configuration for IPv6. The server is responsible for assigning IP addresses and maintaining the states of the client nodes. It maintains a database of the addresses that were assigned to the hosts, thus the name "statefull," as it maintains the status of allocations.

### Operation

The client host sends a request to the IPv6 network, all servers that are connected to the network, receives the request. But only the server assigns an IP to the client host.

## Implementations of IPv6 in XO

Three of the main possible implementations of IPv6 in the XO are described below:

### Manual Allocation

All the hosts should be awarded an IP within the same network. To do this, the command is:
To run this command on the XO, the user must have root permissions.

### Automatic Allocation

To achieve this, a DHCPv6 server must be configured (in any host) and each node of the network must be configured for the DHCPv6 client.
The DHCPv6 server must be configured with the range of IPs that will be available in the pool of address and prefix of the network. On the client, the server that it will “listen” must be configured as well as the network interface that it will use to connect to the DHCPv6 server.
To perform this configuration, both the client and the server, the user must have root permissions.

### Local IP Allocation

Two or more XO connected together, set up an ad-hoc network, which is automatically configured. The IP that is assigned in each node is known as: local link.

## Validation

To validate these implementations, this command must be executed:
A broadcast ping can be done to test the network:
# Linux Networking/Linux Networking Resource

There are a number of places where you can find good information about Linux networking.
There are a wealth of Consultants available. A listing can be found at LinuxPorts Consultants Database
Alan Cox, the current maintainer of the Linux kernel networking code maintains a World Wide Web page that contains highlights of current and new developments in linux Networking at: www.uk.linux.org.
Another good place is a book written by Olaf Kirch entitled the Network Administrators Guide. It is a work of the Linux Documentation Project and you can read it interactively at Network Administrators Guide HTML version or you can obtain it in various formats by ftp from the metalab.unc.edu LDP ftp archive. Olaf's book is quite comprehensive and provides a good high level overview of network configuration under linux.
There is a newsgroup in the Linux news hierarchy dedicated to networking and related matters, it is:
comp.os.linux.networking
There is a mailing list to which you can subscribe where you may ask questions relating to Linux networking. To subscribe you should send a mail message:
On the various IRC networks there are often #linux channels on which people will be able to answer questions on linux networking.
Please remember when reporting any problem to include as much relevant detail about the problem as you can. Specifically you should specify the versions of software that you are using, especially the kernel version, the version of tools such as pppd or dip and the exact nature of the problem you are experiencing. This means taking note of the exact syntax of any error messages you receive and of any commands that you are issuing.
# Linux Networking/Multicast
## Multicast

IP Multicast allows an arbitrary number of IP hosts on disparate IP networks to have IP datagrams simultaneously routed to them. This mechanism is exploited to provide Internet wide "broadcast" material such as audio and video transmissions and other novel applications.
Kernel Compile Options:
A suite of tools and some minor network configuration is required. Please check the Multicast-HOWTO for more information on Multicast support in Linux.
# Linux Networking/IP Transparent Proxy
## IP Transparent Proxy

IP transparent proxy is a feature that enables you to redirect servers or services destined for another machine to those services on this machine. Typically this would be useful where you have a linux machine as a router and also provides a proxy server. You would redirect all connections destined for that service remotely to the local proxy server.
Kernel Compile Options:
Configuration of the transparent proxy feature is performed using the ipfwadm command
An example that might be useful is as follows:
This example will cause any connection attempts to port telnet (23) on any host to be redirected to port 2323 on this host. If you run a service on that port, you could forward telnet connections, log them or do whatever fits your need.
A more interesting example is redirecting all http traffic through a local cache. However, the protocol used by proxy servers is different from native http: where a client connects to www.server.com:80 and asks for /path/page, when it connects to the local cache it contacts proxy.local.domain:8080 and asks for www.server.com/path/page.
To filter an http request through the local proxy, you need to adapt the protocol by inserting a small server, called transproxy (you can find it on the World Wide Web). You can choose to run transproxy on port 8081, and issue this command:
The transproxy program, then, will receive all connections meant to reach external servers and will pass them to the local proxy after fixing protocol differences.
# Linux Networking/IP Firewall (for Linux-2.0)
## IP Firewall (for Linux-2.0)

IP Firewall and Firewalling issues are covered in more depth in the Firewall-HOWTO. IP Firewalling allows you to secure your machine against unauthorized network access by filtering or allowing datagrams from or to IP addresses that you nominate. There are three different classes of rules, incoming filtering, outgoing filtering and forwarding filtering. Incoming rules are applied to datagrams that are received by a network device. Outgoing rules are applied to datagrams that are to be transmitted by a network device. Forwarding rules are applied to datagrams that are received and are not for this machine, i.e. datagrams that would be routed.
Kernel Compile Options:
Configuration of the IP firewall rules is performed using the ipfwadm command. As I mentioned earlier, security is not something I am expert at, so while I will present an example you can use, you should do your own research and develop your own rules if security is important to you.
Probably the most common use of IP firewall is when you are using your linux machine as a router and firewall gateway to protect your local network from unauthorized access from outside your network.
The following configuration is based on a contribution from Arnt Gulbrandsen, <agulbra@troll.no>.
The example describes the configuration of the firewall rules on the Linux firewall/router machine illustrated in this diagram:
The following commands would normally be placed in an rc file so that they were automatically started each time the system boots. For maximum security they would be performed after the network interfaces are configured, but before the interfaces are actually brought up to prevent anyone gaining access while the firewall machine is rebooting.
Good firewall configurations are a little tricky. This example should be a reasonable starting point for you. The ipfwadm manual page offers some assistance in how to use the tool. If you intend to configure a firewall, be sure to ask around and get as much advice from sources you consider reliable and get someone to test/sanity check your configuration from the outside.
# Linux Networking/Mobile IP
## Mobile IP

The term "IP mobility" describes the ability of a host that is able to move its network connection from one point on the Internet to another without changing its IP address or losing connectivity. Usually when an IP host changes its point of connectivity it must also change its IP address. IP Mobility overcomes this problem by allocating a fixed IP address to the mobile host and using IP encapsulation (tunneling) with automatic routing to ensure that datagrams destined for it are routed to the actual IP address it is currently using.
A project is underway to provide a complete set of IP mobility tools for Linux. The Status of the project and tools may be obtained from the: Linux Mobile IP Home Page.
# Linux Networking/NAT - Network Address Translation
## NAT - Network Address Translation

The IP Network Address Translation facility is pretty much the standardized big brother of the Linux IP Masquerade facility. It is specified in some detail in RFC-1631 at your nearest RFC archive. NAT provides features that IP-Masquerade does not that make it eminently more suitable for use in corporate firewall router designs and larger scale installations.
An alpha implementation of NAT for Linux 2.0.29 kernel has been developed by Michael.Hasenstein, Michael.Hasenstein@informatik.tu- chemnitz.de. Michaels documentation and implementation are available from:
Linux IP Network Address Web Page
Newer Linux 2.2.x kernels also include some NAT functionality in the routing algorithm.
# Modern Photography/Digital image formats

Digital image formats are an important part of modern photography. Regardless of whether you are shooting in digital or analog, it's highly likely that any successful image will eventually be published digitally. In addition, virtually all modern printing now relies upon digital inputs, which means that printing a book or poster-scale reproduction of an analog photograph will necessitate digitization before printing can proceed. When shooting digital, however, our camera stores the image in a digital format from the moment of capture, so our photographs are tied to digital image formats from their very inception. Let's take a closer look at what that means for our images.

## Fundamentals

There are two types of digital images: bitmap (also known as raster) and vector.
Bitmap images are those in which the image is divided in to tiny squares (known as pixels), each of which has color information associated. You cannot 'zoom in' past the available data in a bitmap image, they are thus said to be of a limited or fixed resolution.
By contrast, vector images are those in which mathematical formulae are stored to define the shapes within an image. Vector images can be zoomed infinitely, are are thus not bound to a particular resolution.
Note that it is possible to convert a bitmap image to a vector image with some accuracy and contortion, this process is sometimes known as 'tracing'. Inversely, it is easy to convert a vector image to a bitmap image at a particular resolution, this process is known as rendering or rasterizing.
Because bitmap images match the sensor mechanism in most photographic equipment and are extremely widely used, bitmap images are almost always the appropriate choice for the storage of photographs, and will be assumed throughout the rest of this document.

## Quality vs. Quantity

* Resolution
* Raw vs. JPEG
* Lossy vs. non-lossy

## Color depth

* Examples from black and white through simple GIF to HDRI

## Metadata

* GPS
* Rights
* Timestamp
* Camera and lens information
* Colorspace
* Print resolution
* Other examples

## Portability

* Platform considerations
* Commercial versus open source software

## Long term accessibility

* Archival concerns
# Modern Photography/Collection

The collection of photographs could be said to have popularly begun in the 20th century.
The pursuit reached relative maturity in the closing decades of the 20th century.

## Reasons for collecting

Why do we collect?

### Originals versus reproductions

Original prints can often be said to have a beauty distinct from printed reproductions more widely available in books.

## Selection criteria

While selection criteria are ultimately personal, many collectors have specific strategies based upon raw personal response and/or technical and aesthetic merit.
In addition, many collectors focus their collections on a particular subject (for example a geographic region, or images containing a certain visual subject), group of photographers (for example photographers from a certain country), or time period, images produced using certain cameras or processes, or some combination of these.
# Outline of U.S. History

A chronological look at how the United States took shape—from its origins as an obscure set of colonies on the Atlantic coast a little more than 200 years ago into what one political analyst today calls “the first universal nation.”

## Contents

* Early America
* The Colonial Period
* The Road to Independence
* The Formation of a National Government
* Westward Expansion and Regional Differences
* Sectional Conflict
* The Civil War and Reconstruction
* Growth and Transformation
* Discontent and Reform
* War, Prosperity, and Depression
* The New Deal and World War II
* Postwar America
* Decades of Change: 1960-1980
* The New Conservatism and a New World Order
* Bridge to the 21st Century
* Bibliography

### Picture profiles

* Becoming a nation
* Transforming a nation
* Turmoil and change
* 21st century nation
* Monuments and memorials

## Acknowledgements

This book is derived from the Outline of U.S. History published by the U.S. Department of State's Bureau of International Information Programs. (According to The State Department, “Unless a copyright is indicated, information on State Department websites is in the public domain and may be copied and distributed without permission.”) The first edition (1949-50) was produced under the editorship of Francis Whitney, first of the State Department Office of International Information and later of the U.S. Information Agency. Richard Hofstadter, professor of history at Columbia University, and Wood Gray, professor of American history at The George Washington University, served as academic consultants. D. Steven Endsley of Berkeley, California, prepared additional material.
It has been updated and revised extensively over the years by, among others, Keith W. Olsen, professor of American history at the University of Maryland, and Nathan Glick, writer and former editor of the USIA journal, Dialogue. Alan Winkler, professor of history at Miami University (Ohio), wrote the post-World War II chapters for previous editions. The edition from which this book is derived has been revised and updated by Alonzo L. Hamby, Distinguished Professor of History at Ohio University.
# Outdoor Survival/Water in the desert

In the situation one is stranded in the desert, there are two essentials to surviving: finding shelter away from the sun and staying hydrated. There are a few sources of water in the desert, which are listed in this article.

## Staying hydrated

Foremost, if you have bottled water with you, you should not ration it. Instead, drink it all at once — people have been found dead with water remaining in their bottle. Assuming there are no bodies of freshwater around (such as a river), plants, the air, and animals are the only source of water. Some plants, especially some species of cactus, contain water in a form that can be tapped and drunk directly. More often, however, the moisture in a plant cannot be obtained by any method other than the use of a still, which can retrieve water from the air.
Water can be added to the surrounding air by placing plant parts in the still (but outside the area for capturing the pure water). A simple still can be constructed of plastic sheeting, some rocks, and a cup. Simply dig a hole deep enough to hold the cup, with a couple of inches to spare. The wider the still, the better, since it will have more surface area for water to condense on. Place the cup in the center of the hole and cover the hole with plastic (clear plastic is better than opaque, since it absorbs less heat). Use rocks to secure the edges of the plastic and place a small rock in the center of the plastic sheet to pull it down so that water condensing on the plastic drips into the cup. Such a still does not produce enough water for a person to live on indefinitely, but even a little bit of water can improve one's chances of survival.
If there is no available liquid and you are severely dehydrated, drinking urine can become an extreme survival option.

## Not Overhydrating

Any activity or situation that promotes heavy sweating can lead to water intoxication when water is consumed to replace lost fluids. Persons working in extreme heat and/or humidity for long periods must take care to drink and eat in ways that help to maintain electrolyte balance. Even people who are resting quietly in extreme heat or humidity may run the risk of water intoxication if they drink large amounts of water over short periods for rehydration.

## What not to drink

Drinking alcoholic beverages will slake your thirst temporarily, but due in part to the diuretic nature of alcohol, will leave you more dehydrated than before. Since alcohol is a poison, the liver aggressively removes it, and a lot of water in the process. Alcohol and water bond covalently, and boiling alcoholic drinks will not remove the alcohol any faster than it will remove the water. Drinking saltwater will lead to water being drained from the body, because of osmosis.

## See also

Outdoor Survival/Water

## External links

* A guide to "making water" in the desert
* Desert Hiking Safety - Dehydration
(source: deleted Wikipedia article Water in the desert
# PSP/Welcome
## Welcome!

| Preparing for homebrew | Downloading homebrew | Developing homebrew |
| Install Custom Firmware on your PSP by following PSP/Custom Firmware Installation. | Browse the PSP/Homebrew List', the PSP/Emulation List, the PSP/PRX Plugins list for recommended homebrew and mods. | Start developing homebrew for PSP by reading the PSP Programming Guide. |