http://what-is-what.com/ Questions recently asked on What-Is-What.com en Copyright 2006-2007 What-Is-What.com Wed, 15 Apr 2026 13:42:08 UTC Wed, 15 Apr 2026 13:42:08 UTC Dotan typing in Kate http://what-is-what.com/what_is/telepresence.html Telepresence is the action or simulation of remote attendance. Although true stimulation of all five human senses from a remote environment is not possible with current technology, high-quality remote video and audio feeds are termed telepresence for purposes of research and product marketing. Additionally, work is advancing in providing remote stimulation of the senses of touch and to a lesser degree smell. Remote stimulation of the sense of taste does not seem technologically feasible for the foreseeable future. The first known detailed description of a telepresence system is attributed to the science fiction story Waldo, published in 1942. Forty years later academics from the Massachusetts Institute of Technology began actively developing practical two-way audio and video communications systems. Although far from the true-immersion experience described in science fiction, audio and video proved to be adequate for describing complex ideas and providing a sense of companionship. Therefore early telepresence systems marketed for consumer and business use centered mostly on the establishment of a sense of attendance for people separated by large distances in which arranging an actual physical meeting would be costly, time consuming, or otherwise impractical. Today the field of telepresence is generally divided into two separate fields. The true science of telepresence, which simulates an immersive experience encompassing most or all of the user's senses, remains a subject of active research. Limited telepresence, usually restricted to audio and video, is often termed teleconferencing or videoconferencing. Teleconferencing continues to be actively developed by high-technology companies such as Cisco, and may encompass additional features such as sharing digital files, specifically-designed telepresence or teleconferencing rooms, and specialty hardware and software that maintain quality communications for prioritized senses under adverse network conditions. Fri, 13 Jan 2012 10:37:34 UTC http://what-is-what.com/what_is/telepresence.html http://what-is-what.com/what_is/facebook.html Facebook is a social networking service that allows users to post profiles and interact with the profiles of other users. It was founded in February 2004 and is currently reckoned to have 750 million active users. The site was founded by four Harvard computer science undergraduates, Mark Zuckerberg, Eduardo Saverin, Dustin Moskovitz and Chris Hughes. Originally Facebook was only open to students of Harvard University, before those from other Ivy League institutions and Stanford University were also accepted, followed by high school students and then anyone over the age of 13. Facebook is named after the directories of students produced by American universities, especially at the beginning of each year to help students get to know each other. Zuckerberg is the current CEO and public face of the company and owns a 24% stake in it. The majority of Facebook's revenue comes from advertising and Microsoft is their sole partner for serving banner adverts. Facebook has a lower click through rate (the amount of times an advert is clicked on) than much advertising on the web. There are a number of reasons why this might be so, including the young usership who are used to ignoring ads, the use of ad-blocking software and the nature of the media - people use it for writing messages, which can make adverts difficult to see. Many people also check the site on their smart phones, so even if they are using O2, they may well not see an ad for o2.co.uk when they are looking at their Facebook feed. A Facebook user can create a profile with pictures and a list of personal information, including personal relationships, job, religious beliefs etc. Users can communicate with each other either by writing on a 'wall', a real time public space that is visible for visitors to see, or through messages which are akin to emails. Users can set their 'status' to tell others what they are doing or feeling at that moment, they can also 'poke' others, which means other users are told that they have been 'poked'. The site also has an instant messaging service. It is possible to sell things on Facebook via Marketplace, and to send virtual presents via Gifts. In 2008 Facebook gained an Alexa ranking of 2, which as of August 2011 it still retains. The site is the most popular social networking site in the USA, Canada and the UK. The site has been banned, at least for a period of time, in China, Pakistan and Syria among other countries, and its instrumental influence has been claimed in the protests of the Arab spring, most notably in Egypt where a man named his newly born daughter 'Facebook'. Sat, 14 Apr 2012 10:07:22 UTC http://what-is-what.com/what_is/facebook.html http://what-is-what.com/what_is/git.html Git is an open source version control system. Git is developed and maintained by the creator of the Linux kernel. Git stores complete files each time the user commits his changes, making recovery and version-diffing reliable, responsive, and simple. This is in contrast to other version control systems which store complete versions as "Deltas" or descriptions of the changes between versions of a file. If a file has not changed between commits then Git simply links to the last changed version. Git was developed following a dispute with the author of the BitKeeper version control system used in the development of the Linux kernel. Since no other open-source version control system existed which matched BitKeeper's performance it was decided to design a new system from the ground up. The first stable Git release was announced less than nine months from the first line of code having been written. After Git's initial jump to maturity, there have been no need for additional features and few bugs to fix. Therefore, Git has remained in the 1.x branch for over six years and there are no plans for a Git 2.0 release. As a side-effect of being written by an OS kernel developer, Git functions much like a file system. Additionally, Git enjoys many low-level optimizations in regard to network performance. This makes Git an ideal open-source inplementation of off-site home-directory versioning and backup, similar to Apple's Time Machine. However, no intuitive GUI or file manager integration exists for Git so command-line control of versioning and backup restoration is still necessary. Thu, 04 Aug 2011 13:23:51 UTC http://what-is-what.com/what_is/git.html http://what-is-what.com/what_is/appspy.html Appspy.com is an iPhone game review website. Founded in February 2010 by Australian media production firm Hyper Focus Media, Appspy provides objective game reviews, iPhone news, and application price tracking. Price drop notification is provided on both a subscription and non-subscription basis. Users can register to be notified via email of price changes in games which they've tagged, or can simply browse the "Latest Price Drop" panel to find deals. Additionally, registered users can comment on reviewed applications and share their opinions with other users. With 19 categories of games and a rate of almost 4000 game reviews per month, Appspy is quickly becoming one of the most recognized and respected independent iPhone and iPad game review websites in the Apple iDevice user community. In addition to written reviews, Appspy also produces detailed video reviews of iPhone games which demonstrate gameplay, features, and even the occasional bug. Videos clearly show the application loading and being used in an interactive manner, providing the viewer with real-life perception of the game's responsiveness and UI quirks. Instead of the standard screencast method, Appspy videos show user interaction with the application via shadowed fingers touching a clear iPhone screen, filmed from above the device. Despite the analogue nature of this method, the content is crystal clear and there is no perceived loss of screen clarity in the videos. The inclusion of the user's fingers interacting with the device provide valuable insight into the game's responsiveness and character. Tue, 05 Oct 2010 06:43:11 UTC http://what-is-what.com/what_is/appspy.html http://what-is-what.com/what_is/go-oo.html Go-oo is a community-developed fork of Sun's Open Office office suit. Go-oo contains features and improvements that for technical or legal reasons cannot be included in Sun's version of Open Office. Most Linux distributions today use Go-oo instead of the standard Open Office packages, however, the splash screen and "About" dialogs usually remain the standard Open Office versions. This is at Sun's request, to enhance brand recognition and is in stark contrast to Mozilla's stance on Firefox forks, notably Iceweasel. Although Open Office is open source, Sun does not accept contributions from outside Sun unless the developer gives Sun ownership of the contributed code. This ownership means that Sun can release this code under what ever license Sun chooses. Most code is released twice: once in OOo (Open Office) under the GPL license, and once again in Star Office under a proprietary Sun license. Star Office, Sun's commercial office suit, is built from much of the same code base as OOo, however being a proprietary application it cannot incorporate GPL code. Community frustration regarding Sun's licensing requirements and refusal to add critical features catalyzed several forks of Open Office, which is explicitly permitted under the GPL license. Go-oo is the leading OOo fork for Linux, incorporating enhanced compatibility with competing office suits, snappier performance, and additional features. Compatibility with other office suites is provided by filters capable of parsing Microsoft Office's native OOXML format, MS Works, and Lotus Word Pro files. Snappier performance is seen is faster startup times and improved code profiling. Some of the more useful features in Go-oo that are missing from OOo include SVG support, VBA macro support, 3D transition effects, and a built-in multimedia framework. Tue, 06 Jan 2009 19:42:11 UTC http://what-is-what.com/what_is/go-oo.html http://what-is-what.com/what_is/url.html URL is an acronym for Uniform Resource Locator. URL is the technical term for what is often called a "web address". It is the address by which computers and documents on the Internet can be located. The URL was invented by Tim Berners-Lee as one of his many contributions to the World Wide Web. The URL is a short text string that contains the name of a computer on the Internet, a protocol for communicating with that computer, a path and filename of a document on that computer, and sometimes additional information as well. The inclusion of all this information in a single string is allows for seamless interaction between computers on the Internet and rapid exchange of information. The URL was designed to be extensible in the sense that as new types of documents are added to the Internet, the URL would be able to adapt and uniquely identify each document with regard to each new document format's needs. A full URL consists of a service name, followed by a colon and a hostname, optionally followed by a colon and a port number, followed by a path which ends in a filename or directory. An example of a full URL looks like this: "service:hostname.com:80/directory/file.html". Most URLs that are handled by humans are the addresses of documents on the World Wide Web. These URLs usually specify the HTTP protocol and have the port number eliminated. Additionally, the hostname of a WWW address begins with two forward slashes. An example of such a URL looks like this: "http://hostname.com/". Note that in this example the path specified is a single forward slash, and no file name was specified. This tells the webserver that you are requesting the default file in the topmost public directory of the server. If the webserver has no default file configured then it may return either a list of the files in the directory or an error. A common user error is to specify a URL with no path. Although most webservers are configured to handle this error by automatically assuming that the user wants the default document in the topmost directory, this causes unnecessary server load and may lead to the wrong document being served. Although a URL specifies a specific document's location on the Internet, electronic documents can be easily copied and therefore may have more than one location. Hence, the concepts of URN (Uniform Resource Name) and URI (Uniform Resource Identifier) have been developed. URNs specify the name of a particular resource, regardless of it's location. URIs are simply complete URLs in which the filename is a URN. For example, two webservers may both have a copy of the book 1984. The book may have any filename, but the International Standard Book Number for 1984 will always be "ISBN 0-452-28423-6". Therefore, the URN of the book 1984 would logically be "isbn.0-452-28423-6". A URL of the type "http://server1.com/isbn.0-452-28423-6" would therefore be a URI for the book 1984. Another URI for the same book could possibly be "http://server2.net/books/isbn.0-452-28423-6". Both URIs would ideally point to identical documents. The difference between a URL and a URI is often arbitrary, as most documents on the World Wide Web are not named by any standards organization. Fri, 23 Nov 2007 18:40:21 UTC http://what-is-what.com/what_is/url.html http://what-is-what.com/what_is/storm.html The Storm Botnet is a distributed computer network consisting of computers remotely controlled without their owner's knowledge. Computers in the Storm Botnet are home and small office machines running the Microsoft Windows operating system which have been infected by the Storm worm. Storm got it's name as the worm was first spread though spam email with the subject "230 dead as storm batters Europe." Today, the Storm Botnet is considered to be the largest botnet in the world, with as many as 5 million computers under it's control. Efforts to combat Storm have been met with targeted resistance, suggesting that artificial intelligence and automated adaptive defense techniques are being utilized. The Storm worm, termed Nuwar by Microsoft but popularly referred to as Storm, was first identified in January 2007. Within one week of it's discovery, the worm had successfully infected over one million personal computers. This success is credited to the ambiguous yet catchy email subject lines in propagation emails, which like the original "storm" subject often referred to current news events. When these email messages are opened in an insecure email client such as Outlook or Outlook Express, an executable attachment downloads and installs several malware packages to the host computer. Usually, in addition to a trojan and a worm update, a rootkit is installed on the host computer, thereby masking any evidence of infection. In fact, the Storm rootkit had been proven to disable any anti-virus programs running on the computer while leaving it's executable file running. The updated worm then mutates slightly, harvests email addresses in the email client and browser cache, and sends itself to those addresses. Unlike other worms which have a master computer hard-coded into their code, the mutated Storm worm contains only a list of other Storm-infected machines with which it can communicate, but not the address of the botnet master. Communication between each Storm node and the master is performed in a P2P fashion, with each machine functioning as both a slave and as a messenger between nodes. Once a computer is infected with the Storm worm, it becomes part of the Storm Botnet. With 250,000 nodes active at any particular time, the Storm Botnet is estimated to range between 2 million and 5 million computers total. This provides the network with more RAM, disk space, and computing power than many of the world's most powerful supercomputers. However, Storm's strength is not in it's shear computing resources but rather in it's distributed nature, as the computers consisting of the botnet have more available bandwidth than most countries have in their entirety. DDoS attacks originating from even a tenth of the Storm Botnet could shut down many governments and international organizations such as the United Nations and the Red Cross which today depend upon the Internet for vital communications. However, as of late 2007 the only DDoS attacks attributed to Storm are those targeted at IP addresses that have been used to probe Storm nodes in malware research. Sun, 09 Dec 2007 01:42:53 UTC http://what-is-what.com/what_is/storm.html http://what-is-what.com/what_is/hybrid_vehicle.html A hybrid car is an automobile that has two or more major sources of propulsion power. Most hybrid cars currently marketed to consumers have both conventional gasoline and electric motors, with the ability to power the vehicle by either one independently or in tandem. These vehicles are appropriately termed gas-electric hybrids. Other power sources may include hydrogen, propane, CNG, and solar energy. The technology used depends on the goals set for the vehicle, whether they be fuel efficiency, power, driving range, or reduced greenhouse gas emissions. Consumer oriented hybrid cars, which have been on the market for about ten years, are usually tuned for reduced emissions and driving range. Additionally, owners of hybird vehicles often enjoy social benefits such as prestige and discounted secondary services. Some Chicago hotels as well as hotels in other cities give parking discounts to people driving hybrid cars. Corporate and government fleets that have been in service for twenty years or more are usually tuned for fuel efficiency, often at the cost of driving range, power, and hydrocarbon emissions. A gasoline-electric hybrid car has one or two auxiliary electric motors that supplement the main gasoline engine. Compared to conventional automobiles, the gasoline engine in a gas-electric hybrid is smaller, less powerful, and more efficient. Although the gasoline engine alone would be sufficient to power the vehicle under most circumstances, during maneuvers requiring unusually high power the electric motor is used as well. These conditions include passing, hill climbing, and acceleration from a standstill. Some hybrid cars, such as the Toyota Prius, shut down the gasoline engine under conditions in which the electric motor alone would suffice, such as coasting and breaking. In fact, the Toyota Prius has a special electric-only mode designed for stop-and-go traffic. This is made possible by the super heavy duty electric motor used in the Prius, which is capable of propelling the vehicle from a standstill without the gasoline assist. Thus, in contrast to most other hybrid vehicles, the Prius actually uses the electric motor more than the gasoline engine. Many of the technologies found in hybrid vehicles would benefit vehicles of any type, including conventional gasoline automobiles. However, the engineering and manufacturing costs associated with these technologies often would increase the price of the vehicle to the point where the fuel savings are negligible in comparison. Only in tax-subsidized electric and hybrid vehicles are these technologies practical, in which associated cost increases are absorbed by the government instead of the manufacturer or consumer. These technologies include regenerative braking, aerodynamic refinements, and lightweight building materials. Fri, 10 Jun 2011 17:29:09 UTC http://what-is-what.com/what_is/hybrid_vehicle.html http://what-is-what.com/what_is/teleportation.html Teleportation is the transfer of physical objects from one place to another, distant place, without transferring the physical particles that constitute the original object. By most definitions, the object in its original location is either destroyed or rendered otherwise unrecognizable and unable to function. This limits teleportation devices to transportation roles only, incapable of duplicating or manufacturing objects. Although teleportation devices were until recently considered by the scientific community to stay confined to the realm of science fiction, recent understandings of quantum mechanics have led to the development of successful teleportation techniques. The current state of the art in teleportation technology, having successfully moved relatively large masses relatively large distances, relies on the uncertainty principle and quantum entanglement phenomenon. The uncertainty principle states that the more information that is extracted from an object, the more the object is malformed. The point in which the object is so malformed as to prevent further scanning occurs well before enough information is extracted to produce an exact copy. Quantum entanglement allows the quantum state of one particle to be predicted based upon the quantum state of another particle that had once been in contact with it. Thus, a teleportation sending station and receiving station can be prepared by bringing two such particles into contact, and then bringing one to the sending station, and the other to the receiving station. The particle at the sending station is then scanned along with the object to be teleported. The scanning process malforms both the particle and the object. The scanned information is then sent to the receiving station, which then performs the reverse process to raw material together with the second particle. As the second particle is currently in the same quantum state as the first particle, together with the original object, the finished product is identical to the original object. The first objects to be successfully teleported were photons, or light particles. These massless particles are ideal for such experimentation as the have relatively few quantum states and readily entangle with other photons. As early as 1998 experiments have proven with over 75% accuracy that the quantum state of a photon can be imparted on a distant photon by way of an intermediate photon that is quantumly entangled with the target photon. While this method could theoretically be used to transmit data, it would not permit the movement of tangible objects. Six years later, two separate research teams had independently succeeded in teleporting collections of atoms. Although the atoms themselves had been teleported, their respective arrangement had not been preserved. Thus, the current state of the art does not permit the teleportation of large or complex structures. However, new developments in technology, as well as a more thorough understanding of quantum mechanics, may help researchers overcome that obstacle. Thu, 25 Oct 2007 18:14:46 UTC http://what-is-what.com/what_is/teleportation.html http://what-is-what.com/what_is/decibel.html The decibel is the common measure of sound intensity and radio signal strength. Although it has never been ratified by any governing standards body, its suitability to measuring ratios and losses has led to widespread adoption of the decibel in industry and research. Although most commonly used today as a measure of sound intensity in air, the decibel was actually invented to measure the loss of sound intensity in electrical wire. In its regular form, the decibel is abbreviated "dB". When used to measure ratios of other forms of energy intensity the abbreviation is postfixed with appropriate, though non-standard, abbreviation. For instance, "dBk" indicates kilowatt loss, and "dBv" indicates voltage loss. Sound is perceived by humans and most animals in a logarithmic manner of intensity. Therefore, the bel system of sound intensity measurement is also logarithmic. Zero on the bel scale is the human hearing threshold, perceivable only by the young, and 1 is the level that any healthy human can perceive. Each increase of 1 point on the bel scale corresponds to a tenfold increase in noise intensity, although due to the logarithmic nature of human hearing, is perceived only as a threefold increase. As the bel system measurements are too large for practical use, the decibel system is more commonly used. As the name implies, an increase of ten decibels is equivalent to an increase of one bel. However, a decibel is not considered one tenth of a bel, as the scale is logarithmic. A convenient consequence of the logarithmic scale is that a change of 1 decibel at normal room levels (40-50 decibels) is the just noticeable difference for most people. As sound waves expand isotropically through air in a three-dimensional manner, their intensity reduces as an inverse function of the square of the distance from the sound source. This translates to a 6 decibel decrease for every doubling of distance. Studies have led to the establishment of safe sound levels for long term human exposure that, when followed, significantly reduce the danger of hearing loss. The United States Environmental Protection Agency has established 70 decibels as the maximum safe daily average. In practice, this is only slightly higher than the natural sound levels in most office buildings, and is significantly lower than the ambient sound levels in almost all industrial work environments. For instance, the manufacturing, construction, and transportation industries all expose their workers to 90 decibels on a regular basis, with the ambient sound level rarely going below 65 decibels. Improved equipment designed specifically for reduced sound levels and mandatory use of hearing protection help prevent sound-related injuries. Sat, 20 Oct 2007 09:16:14 UTC http://what-is-what.com/what_is/decibel.html