Wiki

Un wiki o una wiki (del hawaiano wiki, ‘rápido’) es un sitio web cuyas páginas pueden ser editadas por múltiples voluntarios a través del navegador web. Los usuarios pueden crear, modificar o borrar un mismo texto que comparten. Los textos o tienen títulos únicos. Si se escribe el título de una en algún lugar del wiki entre dobles corchetes, esta palabra se convierte en un a la página wiki.

En una página sobre, por ejemplo, puede haber una palabra como o que esté marcada como palabra perteneciente a un título de página wiki. La mayor parte de las implementaciones de wikis indican en el URL de la página el propio título de la página wiki (en Wikipedia ocurre así: http://es.wikipedia.org/wiki/Alpinismo), facilitando el uso y comprensibilidad del link fuera del propio sitio web. Además, esto permite formar en muchas ocasiones una coherencia terminológica, generando una ordenación natural del contenido.

La aplicación de mayor peso y a la que le debe su mayor fama hasta el momento ha sido la creación de enciclopedias colectivas, género al que pertenece la Wikipedia. Existen muchas otras aplicaciones más cercanas a la coordinación de informaciones y acciones, o la puesta en común de conocimientos o textos dentro de grupos.

La mayor parte de los wikis actuales conservan un historial de cambios que permite recuperar fácilmente cualquier estado anterior y ver qué usuario hizo cada cambio, lo cual facilita enormemente el mantenimiento conjunto y el control de usuarios nocivos. Habitualmente, sin necesidad de una revisión previa, se actualiza el contenido que muestra la página wiki editada.

Historia

El origen de los wikis está en la comunidad de patrones de diseño, cuyos integrantes los utilizaron para escribir patrones de programación. El primer WikiWikiWeb fue creado por Ward Cunningham, quien inventó y dio nombre al concepto wiki, y produjo la primera implementación de un servidor WikiWiki para el repositorio de patrones del Portland (Portland Pattern Repository) en1995. En palabras del propio Cunningham, un wiki es «la base de datos en línea más simple que pueda funcionar» (the simplest online database that could possibly work). El wiki de Ward aún es uno de los sitios wiki más populares.

En enero de 2001, los fundadores del proyecto de enciclopedia Nupedia, Jimbo Wales y Larry Sanger, decidieron utilizar un wiki como base para el proyecto de enciclopedia Wikipedia. Originalmente se usó el software UseMod, pero luego crearon un software propio, MediaWiki, que ha sido adoptado después por muchos otros wikis.

Actualmente, el wiki más grande que existe es la versión en inglés de Wikipedia, seguida por varias otras versiones del proyecto. Los wikis ajenos a Wikipedia son mucho más pequeños y con menor participación de usuarios, generalmente debido al hecho de ser mucho más especializados. Es muy frecuente, por ejemplo, la creación de wikis para proveer de documentación a programas informáticos, especialmente los desarrollados en software libre.

Ventajas

La principal utilidad de un wiki es que permite crear y mejorar las páginas de forma instantánea, dando una gran libertad al usuario, y por medio de una interfaz muy simple. Esto hace que más gente participe en su edición, a diferencia de los sistemas tradicionales, donde resulta más difícil que los usuarios del sitio contribuyan a mejorarlo.

Dada la gran rapidez con la que se actualizan los contenidos, la palabra «wiki» adopta todo su sentido. El «documento» de hipertexto resultante, denominado también «wiki» o «WikiWikiWeb», lo produce típicamente una comunidad de usuarios. Muchos de estos lugares son inmediatamente identificables por su particular uso de palabras en mayúsculas, o texto capitalizado - uso que consiste en poner en mayúsculas las iniciales de las palabras de una frase y eliminar los espacios entre ellas - como por ejemplo en Este Es Un Ejemplo. Esto convierte automáticamente a la frase en un enlace. Este wiki, en sus orígenes, se comportaba de esa manera, pero actualmente se respetan los espacios y sólo hace falta encerrar el título del enlace entre dos corchetes.

Características

Un wiki permite que se escriban artículos colectivamente (co-autoría) por medio de un lenguaje de wikitexto editado mediante un navegador. Una página wiki singular es llamada «página wiki», mientras que el conjunto de páginas (normalmente interconectadas mediantehipervínculos) es «el wiki». Es mucho más sencillo y fácil de usar que una base de datos.

Una característica que define la tecnología wiki es la facilidad con que las páginas pueden ser creadas y actualizadas. En general no hace falta revisión para que los cambios sean aceptados. La mayoría de wikis están abiertos al público sin la necesidad de registrar una cuenta de usuario. A veces se requiere hacer login para obtener una cookie de «wiki-firma», para autofirmar las ediciones propias. Otros wikis más privados requieren autenticación de usuario.

http://es.wikipedia.org/wiki/Wiki

Resumen

Un Wiki (del hawaiano wiki wiki) es un sitio web colaborativo que puede ser editado por varios usuarios.

Los usuarios de una wiki pueden así crear, editar, borrar o modificar el contenido de una página web, de una forma interactiva, fácil y rápida; dichas facilidades hacen de una wiki una herramienta efectiva para la escritura colaborativa.

Nos basaremos en la historia de wikipedia uno de los wikis mas famosos del momento.

Wikipedia empezó como proyecto en lengua inglesa el 15 de enero de 2001.

La idea original prendió pronto en otros idiomas, ya que sólo dos meses más tarde, el 16 de marzo de 2001, la Wikipedia en alemán, fue la segunda en ser creada, pero paradójicamente hasta dos meses después de su creación no tuvo colaboradores. En este período el usuario Cdani usó la Wikipedia en alemán para hacer las pruebas para la Wikipedia en catalán, la segunda en contener artículos. Al 31 de marzo de 2008 todas las ediciones habían sumado 9.790.407 artículos, de los cuales 2.259.431 (24,136%) corresponden a la Wikipedia en inglés (para actualizar consultar Estadísticas multilingües).

En marzo de 2000 Jimbo Wales creó Nupedia, un proyecto de enciclopedia libre basado en un ambicioso proceso de revisión por pares, diseñado para hacer sus artículos de una calidad comparable a la de las enciclopedias profesionales gracias a la participación de eruditos (principalmente doctorandos  y académicos), a los que se proponía colaborar de modo no remunerado.

Debido al lento avance del proyecto, en 2001 se creó un wiki vinculado a Nupedia cuya finalidad inicial era agilizar la creación de artículos de forma paralela, antes de que éstos pasaran al sistema de revisión por expertos.

Existe cierta polémica entre los fundadores de Nupedia sobre quién propuso originalmente la idea de usar un wiki a Jimbo Wales, si Larry Sanger o bien una tercera persona,1 pero el caso es que el éxito de aquel "pequeño proyecto paralelo" (Wikipedia) acabó eclipsando a Nupedia, que dejó de funcionar en 2003.

http://www.monografias.com/trabajos-pdf/que-es-wiki/que-es-wiki.shtml

Para que sirve un wiki.

Wiki resulta ser una ayuda útil para introducirse en la navegación por el portal, agregar contenidos e incluso servir como foro de consulta y de opinión sobre el estado y el uso de la página web de recursos humanos.

Puede crearse, por ejemplo, entre usuarios de la página web, un foro de ayuda, para que de manera interactiva pueda compartirse información relativa a esta aplicación de software libre.

En definitiva, compartiendo información entre usuarios damos un paso más en dirección participativa.

http://mitareafacil.blogspot.com/2008/05/para-que-sirve-un-wiki.html

MICROWAVE

MICROWAVE 


MICROWAVE OVEN IN A KITCHEN. 
A microwave is an appliance used in the kitchen to heat food that works by generating electromagnetic waves at microwave frequencies, around 2.45 GHz 

What really makes the 2.4GHz radiation is used in microwave excitation of the OH bond. This link is present mainly in the water, but also in many other compounds. The ease of this link is more exciting if H is relatively "free" hydrogen bonds without the "attention", as in the ice and in some hydrocarbons. 
Referring to excitation of the OH bond does not mean that the molecule rotates, just to absorb the microwave energy passes link the fundamental rotational-vibrational state to a higher "excited." This new state contributes to higher average translational energy of molecules (as microscopic) and thus its temperature (measured macroscopic). (Physical Chemistry Vol.2 Cap. 21 Aut: Ira N. Levine) 
Some features: 
If a food does not contain OH bonds, is not heated. So most do not heat empty plates. 
To heat something dry, water must be added. 
The dehydrated or make the cooking of food beyond its heating (to the point of roasting or burning) can trigger damage to the microwave 
The heat is produced where polar molecules moving, ie it can be inside of a potato. Heat flows, as in conventional ovens, outside in the food but the outdoor area is far greater. 
Never put anything with liquid seal, like a raw egg in shell, or a closed glass container. The effect is that water is heated to become steam, which expands, causing great pressure, but could explode. 
Due to some frequency microwave ovens can interfere with Wi-Fi signals and Bluetooth also works in the range of 2.4GHz 

HISTORY 

The microwave is a byproduct of other technology like other inventions. This happened during the course of a research project related to radar, around 1946 in which Dr. Percy Spencer, an engineer at Raytheon Corporation, noticed something very peculiar. I was testing a new vacuum tube called a magnetron when he discovered that a candy bar he had in his pocket had melted. Intrigued and thinking that maybe the chocolate bar had been hit accidentally by these waves, Dr. Spencer did an experiment. This time put some seeds of corn to make popcorn near the tube and, standing some distance away, saw a spark of inventiveness in his eyes move as corn is cooked and puffed and jumping spreading throughout the laboratory. 
The next morning, the scientist decided to put the magnetron near a chicken egg. He was accompanied by a curious colleague, who witnessed how the egg began to vibrate due to increased internal pressure caused by the rapid increase in temperature of its contents. The curious fellow came just as the egg exploded, splashing your face with warm yolk. Dr. Spencer's face, however, lit up with a logical scientific conclusion: what happened to the bar of chocolate, popcorn and now the egg could be attributed to exposure to low energy density of the microwave . And if you could cook an egg so quickly, why not try other foods? Thus began the experiment. 
Dr. Spencer designed a metal box with an opening in which he introduced in the form of microwave energy. This energy, inside the box, could not escape and thus created a higher density electromagnetic field. When you put food temperature food increased rapidly. Dr. Spencer had invented what was to revolutionize the way you cook and laying the groundwork for a multibillion-dollar industry: the microwave. 
The engineers spent working on the invention of Dr. Spencer, improved and modified for practical use. In late 1946, Raytheon Company applied for a patent for using microwaves in the cooking of food. An oven that heated food using microwave energy was installed in a Boston restaurant for testing. In 1947, was released the first commercial microwave oven. These early units were large and bulky, 1.60 m in height and 80 kg. The magnetron is water cooled, so you had to install a pipe especial.También, its price was high, cost about $ 5,000 each. 
There was considerable resistance to these units and were not accepted immediately. Initial sales were disappointing.However, further improvements and refinements oven produced a more reliable and lighter, less expensive and a new air-cooled magnetron, eliminated the need to lay pipes. Finally the microwave reached a level of relative acceptance, particularly in the field of fast food sales. 
Traders had the problem of how they could keep food warm until you buy them, because if decomposed would obviously substantial loss. When you see the use of microwave, could keep the products frozen in place and then were served warm quickly in the microwave. This provided food fresher, less waste and more savings. 
Immediately fast food businesses and restaurants realized that the microwave solved more problems than it created. Upon encountering the same problem of keeping food warm for long periods, restaurant owners began to appreciate the value of the microwave oven in their operations. They can now keep your food refrigerated and heat to the order of customers. 
When the food industry began to recognize the potential and versatility of the invention, it was applied to new and varied uses.Industries began using microwaves to dry potato slices, roasted coffee beans and peanuts. You could thaw, cook and give preasar end meats. Still opening oysters are facilitated with the use of microwaves. Other industries found it convenient to the various applications of microwave heating. Over time, they were used to dry cork, ceramics, paper, leather, snuff, textiles, pencils, flowers, books wet matchstick. Were also used microwave curing synthetic materials like nylon, rubber and urethane. 1 The microwave oven became a necessity for the commercial market and the possibilities seemed endless. 
Technological advances and further development led to a microwave evolved and the scope of the consumer's kitchen.However, there are many myths and misgivings about the new stoves and mysterious electronic "radar", so that flowering was delayed somewhat, but not much. In the seventies more and more people found that the benefits of microwave cooking up for the likely risks and apparently no one died of "poisoning" by radiation, nor was blind, sterile or impotent (at least by the use of ovens microwave). When fears vanished, began to leak a rising tide of acceptance in the kitchens of the United States, contradicting myths and turning the question on demand. He had started the boom. 
In 1975, for the first time, sales of microwave ovens exceeded the number of gas stoves sold. The following year it was reported that 17% of all households in Japan with microwave cooking, compared to only four percent of U.S. households during the year. However, by 1978, microwave ovens graced the kitchens of more than nine million households, approximately 14% in the United States. At the end of 1980, this figure increased by over 25%. In 1986, the microwave became more apparent that the dishwasher and reached 60%, or about 52 million U.S. households. Cooking habits in the United States changed dramatically for the convenience of time and energy saving microwave. If you ever considered luxury, it has evolved thanks to modern technology and by popular demand, a practical necessity for an active world. The expanding market has created a style according to every taste, size and shape to suit every kitchen and affordable to almost any pocket. The options and features, such as the addition of convection heat, baked with sensor, etc.., Satisfy the needs of almost any application in baking, cooking or drying. Now, the magic of baking with microwave has spread worldwide and become a phenomenon INTERNMENT Dr. Percy Spencer, inventor, continued at Raytheon as a consultant "senior" until his death at the age of 76 years. He authored more than 100 patents and was considered a leading expert in the field of microwaves, although lacking a secondary education. 

Most governments, industries and defend WHO1 own use as a health insurance appliance. 
The same manufacturers recommend leaving food at rest a few seconds before removing from the microwave. This is due to injuries and burns from boiling instantánea.2

http://es.wikipedia.org/wiki/Horno_de_microondas

MICROWAVE BACKGROUND RADIATION 

In cosmology, microwave background radiation (Cosmic Microwave Background in English or CMB) is a form of electromagnetic radiation discovered in 1965 that fills the entire universe. Also called cosmic microwave background radiation or cosmic. Said to be the echo that comes from the early universe, or the echo left over from the Big Bang that gave birth to the universe. It features black-body radiation at a temperature of 2.725 K and its frequency belongs to the microwave range at a frequency of 160.2 GHz, corresponding to a wavelength of 1.9 mm. Many cosmologists consider this radiation as the main evidence of the Big Bang cosmological model of the universe. 

FEATURES 


The spectrum of microwave background radiation measured by FIRAS instrument on the COBE satellite is the black body spectrum measured more accurately in nature. Variables and standard error are hidden by the trend. 
The microwave background radiation is isotropic to one part in 105: the changes are just 18 rms μK.1 The spectrophotometer FIRAS (in English The Far Infrared Absolute Spectrophotometer-) on NASA's COBE satellite has measured the spectrum carefully of the microwave background radiation. The FIRAS compared the CMB with a reference black body and could not see any difference in their spectra. Any deviation from the black body that would remain undetected in the CMB spectrum over the range of wavelengths from 0.5 to 5 mm would have a value of about 50 parts per million peak brightness CMB.2 This spectrum of the CMB made the black body more accurately measured in nature. 
This radiation is a prediction of the Big Bang model, since according to this model, the early universe was composed mostly of plasma electrons, photons and baryons (protons and neutrons). The photons were constantly interacting with the plasma by Thomson scattering. The electrons could not be attached to protons and other atomic nuclei to form atoms because the average energy of the plasma was very high, so that the electrons interact with photons constantly through a process known as Compton scattering. As the universe expanded, adiabatic cooling (from the cosmological redshift is a symptom present) caused because the plasma to cool until it is possible that the electrons combine with protons and form hydrogen atoms. This occurred when it reached 3000 K, about 380,000 years after the Big Bang. From that moment, photons could travel freely through space without colliding with electrons scattered. This phenomenon is known as the era of recombination and decay, the microwave background radiation is precisely the result of that period. By going to expand the universe, this radiation was also reducing its temperature, which explains why today is only about 2.7 K. Background radiation is the noise that makes the universe. Said to be the echo that comes from the early universe, or the echo left over from the Big Bang that gave birth to the universe. 
The photons have continued cooling ever since, have now fallen to 2.725 K and the temperature continue to fall as the universe expands. Similarly, radiation from the sky we measure comes from a spherical surface, called surface of last scattering, in which photons were decomposed in the interaction with matter in the early universe, 13.7 billion years ago, are observed on Earth today. The Big Bang suggests that the cosmic background radiation fills all of observable space and that much of the radiation in the universe is in the CMB, which has a fraction of about 10.05 -5 Universo.3 the total density of 
Two of the great successes of the Big Bang theory are the predictions of this black body spectrum almost perfect and detailed forecast of anisotropies in the cosmic microwave background. The recent WMAP has measured precisely these anisotropies over the full sky angular scales of 0.2 ° .4 These can be used to estimate the parameters of the standard Lambda-CDM model of the Big Bang. Some information, such as how the universe can be obtained directly from the CMB, while others, like the Hubble constant, are not restricted and have to be inferred from other medidas.5

http://es.wikipedia.org/wiki/Radiaci%C3%B3n_de_fondo_de_microondas