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[
"Alfio Rapisarda",
"position held",
"apostolic nuncio to Bolivia"
] |
Biography
Alfio Rapisarda was born on 3 September 1933 in Zafferana Etnea, Province of Catania, Italy. He was ordained a priest on 14 July 1957. He earned a doctorate in canon law and entered the diplomatic service of the Holy See in 1962. He completed the course of studies at the Pontifical Ecclesiastical Academy in 1960. His early assignments included stints in Honduras, Brazil, France, Yugoslavia, and Lebanon.On 22 April 1979, Pope John Paul II appointed him Titular Archbishop of Cannae and Apostolic Nuncio to Bolivia and consecrated him a bishop on 27 May.On 29 January 1985, John Paul named him Apostolic Nuncio to Zaire (now the Democratic Republic of the Congo), Apostolic Nuncio to Brazil on 2 June 1992, and Apostolic Nuncio to Portugal on 12 October 2002. In 2004 Portugal and the Holy See signed a new concordat, replacing an outdated one from 1940.Pope Benedict XVI accepted his resignation on 8 November 2008.
| 9
|
[
"Alfio Rapisarda",
"position held",
"Apostolic Nuncio to Brazil"
] |
Biography
Alfio Rapisarda was born on 3 September 1933 in Zafferana Etnea, Province of Catania, Italy. He was ordained a priest on 14 July 1957. He earned a doctorate in canon law and entered the diplomatic service of the Holy See in 1962. He completed the course of studies at the Pontifical Ecclesiastical Academy in 1960. His early assignments included stints in Honduras, Brazil, France, Yugoslavia, and Lebanon.On 22 April 1979, Pope John Paul II appointed him Titular Archbishop of Cannae and Apostolic Nuncio to Bolivia and consecrated him a bishop on 27 May.On 29 January 1985, John Paul named him Apostolic Nuncio to Zaire (now the Democratic Republic of the Congo), Apostolic Nuncio to Brazil on 2 June 1992, and Apostolic Nuncio to Portugal on 12 October 2002. In 2004 Portugal and the Holy See signed a new concordat, replacing an outdated one from 1940.Pope Benedict XVI accepted his resignation on 8 November 2008.
| 11
|
[
"Alfio Rapisarda",
"given name",
"Alfio"
] |
Biography
Alfio Rapisarda was born on 3 September 1933 in Zafferana Etnea, Province of Catania, Italy. He was ordained a priest on 14 July 1957. He earned a doctorate in canon law and entered the diplomatic service of the Holy See in 1962. He completed the course of studies at the Pontifical Ecclesiastical Academy in 1960. His early assignments included stints in Honduras, Brazil, France, Yugoslavia, and Lebanon.On 22 April 1979, Pope John Paul II appointed him Titular Archbishop of Cannae and Apostolic Nuncio to Bolivia and consecrated him a bishop on 27 May.On 29 January 1985, John Paul named him Apostolic Nuncio to Zaire (now the Democratic Republic of the Congo), Apostolic Nuncio to Brazil on 2 June 1992, and Apostolic Nuncio to Portugal on 12 October 2002. In 2004 Portugal and the Holy See signed a new concordat, replacing an outdated one from 1940.Pope Benedict XVI accepted his resignation on 8 November 2008.
| 15
|
[
"Alfio Rapisarda",
"family name",
"Rapisarda"
] |
Biography
Alfio Rapisarda was born on 3 September 1933 in Zafferana Etnea, Province of Catania, Italy. He was ordained a priest on 14 July 1957. He earned a doctorate in canon law and entered the diplomatic service of the Holy See in 1962. He completed the course of studies at the Pontifical Ecclesiastical Academy in 1960. His early assignments included stints in Honduras, Brazil, France, Yugoslavia, and Lebanon.On 22 April 1979, Pope John Paul II appointed him Titular Archbishop of Cannae and Apostolic Nuncio to Bolivia and consecrated him a bishop on 27 May.On 29 January 1985, John Paul named him Apostolic Nuncio to Zaire (now the Democratic Republic of the Congo), Apostolic Nuncio to Brazil on 2 June 1992, and Apostolic Nuncio to Portugal on 12 October 2002. In 2004 Portugal and the Holy See signed a new concordat, replacing an outdated one from 1940.Pope Benedict XVI accepted his resignation on 8 November 2008.
| 16
|
[
"Chã das Caldeiras",
"country",
"Cape Verde"
] |
Chã das Caldeiras (Portuguese pronunciation: [ˈʃɐ̃ dɐʃ kalˈdɐjɾɐʃ]; “Plain of the Calderas”) is a small community of approximately 700 inhabitants in the crater of the volcano Pico do Fogo on the island of Fogo, Cape Verde. The village consists of two main neighborhoods: Portela and Bangaeira, founded in 1920 and 1917, respectively. At an elevation of about 1,700 meters, it is the highest village in Cape Verde. It is part of the municipality of Santa Catarina do Fogo. The main organizing body in the village is the Associação dos Agricultores de Chã (Chã Farmers Association), an agricultural cooperative that holds considerable sway over the local economy. Chã is the only area in Cape Verde that grows significant quantities of grapes and produces export-quality wines.
There is no running water or electricity in Chã, though residents are increasingly using generators at night to light and power their homes. All non-drinking water is collected rainwater, stored in large cistern tanks for use in the dry season (November to July).
| 2
|
[
"World Wide Web",
"different from",
"Internet"
] |
Function
The terms Internet and World Wide Web are often used without much distinction. However, the two terms do not mean the same thing. The Internet is a global system of computer networks interconnected through telecommunications and optical networking. In contrast, the World Wide Web is a global collection of documents and other resources, linked by hyperlinks and URIs. Web resources are accessed using HTTP or HTTPS, which are application-level Internet protocols that use the Internet's transport protocols.Viewing a web page on the World Wide Web normally begins either by typing the URL of the page into a web browser or by following a hyperlink to that page or resource. The web browser then initiates a series of background communication messages to fetch and display the requested page. In the 1990s, using a browser to view web pages—and to move from one web page to another through hyperlinks—came to be known as 'browsing,' 'web surfing' (after channel surfing), or 'navigating the Web'. Early studies of this new behavior investigated user patterns in using web browsers. One study, for example, found five user patterns: exploratory surfing, window surfing, evolved surfing, bounded navigation and targeted navigation.The following example demonstrates the functioning of a web browser when accessing a page at the URL http://example.org/home.html. The browser resolves the server name of the URL (example.org) into an Internet Protocol address using the globally distributed Domain Name System (DNS). This lookup returns an IP address such as 203.0.113.4 or 2001:db8:2e::7334. The browser then requests the resource by sending an HTTP request across the Internet to the computer at that address. It requests service from a specific TCP port number that is well known for the HTTP service so that the receiving host can distinguish an HTTP request from other network protocols it may be servicing. HTTP normally uses port number 80 and for HTTPS it normally uses port number 443. The content of the HTTP request can be as simple as two lines of text:
| 0
|
[
"World Wide Web",
"discoverer or inventor",
"Tim Berners-Lee"
] |
History
The Web was invented by English computer scientist Tim Berners-Lee while working at CERN. He conceived it as an information management system using several concepts and technologies, the most fundamental of which was the connections that existed between information. The first proposal was written in 1989, and a working system implemented by the end of 1990 including the WorldWideWeb browser and an HTTP server. The technology was released outside CERN to other research institutions starting in January 1991, and then to the general public on 23 August 1991. The Web was a success at CERN, and began to spread to other scientific and academic institutions. Within the next two years, there were 50 websites created.CERN made the Web protocol and code available royalty free in 1993, enabling its widespread use. After the NCSA released the Mosaic web browser later that year, the Web's popularity grew rapidly as thousands of websites sprang up in less than a year. Mosaic was a graphical browser that could display inline images and submit forms that were processed by the HTTPd server. Marc Andreessen and Jim Clark founded Netscape the following year and released the Navigator browser, which introduced Java and JavaScript to the Web. It quickly became the dominant browser. Netscape became a public company in 1995 which triggered a frenzy for the Web and started the dot-com bubble. Microsoft responded by developing its own browser, Internet Explorer, starting the browser wars. By bundling it with Windows, it became the dominant browser for 14 years.Tim Berners-Lee founded the World Wide Web Consortium (W3C) which created XML in 1996 and recommended replacing HTML with stricter XHTML. In the meantime, developers began exploiting an IE feature called XMLHttpRequest to make Ajax applications and launched the Web 2.0 revolution. Mozilla, Opera, and Apple rejected XHTML and created the WHATWG which developed HTML5. In 2009, the W3C conceded and abandoned XHTML and in 2019, ceded control of the HTML specification to the WHATWG.The World Wide Web has been central to the development of the Information Age and is the primary tool billions of people use to interact on the Internet.
| 1
|
[
"World Wide Web",
"has part(s)",
"website"
] |
Website
A website is a collection of related web resources including web pages, multimedia content, typically identified with a common domain name, and published on at least one web server. Notable examples are wikipedia.org, google.com, and amazon.com.
A website may be accessible via a public Internet Protocol (IP) network, such as the Internet, or a private local area network (LAN), by referencing a uniform resource locator (URL) that identifies the site.
Websites can have many functions and can be used in various fashions; a website can be a personal website, a corporate website for a company, a government website, an organization website, etc. Websites are typically dedicated to a particular topic or purpose, ranging from entertainment and social networking to providing news and education. All publicly accessible websites collectively constitute the World Wide Web, while private websites, such as a company's website for its employees, are typically a part of an intranet.
Web pages, which are the building blocks of websites, are documents, typically composed in plain text interspersed with formatting instructions of Hypertext Markup Language (HTML, XHTML). They may incorporate elements from other websites with suitable markup anchors. Web pages are accessed and transported with the Hypertext Transfer Protocol (HTTP), which may optionally employ encryption (HTTP Secure, HTTPS) to provide security and privacy for the user. The user's application, often a web browser, renders the page content according to its HTML markup instructions onto a display terminal.
Hyperlinking between web pages conveys to the reader the site structure and guides the navigation of the site, which often starts with a home page containing a directory of the site web content. Some websites require user registration or subscription to access content. Examples of subscription websites include many business sites, news websites, academic journal websites, gaming websites, file-sharing websites, message boards, web-based email, social networking websites, websites providing real-time price quotations for different types of markets, as well as sites providing various other services. End users can access websites on a range of devices, including desktop and laptop computers, tablet computers, smartphones and smart TVs.
| 2
|
[
"World Wide Web",
"has part(s)",
"deep web"
] |
Search engine
A web search engine or Internet search engine is a software system that is designed to carry out web search (Internet search), which means to search the World Wide Web in a systematic way for particular information specified in a web search query. The search results are generally presented in a line of results, often referred to as search engine results pages (SERPs). The information may be a mix of web pages, images, videos, infographics, articles, research papers, and other types of files. Some search engines also mine data available in databases or open directories. Unlike web directories, which are maintained only by human editors, search engines also maintain real-time information by running an algorithm on a web crawler.
Internet content that is not capable of being searched by a web search engine is generally described as the deep web.Deep web
The deep web, invisible web, or hidden web are parts of the World Wide Web whose contents are not indexed by standard web search engines. The opposite term to the deep web is the surface web, which is accessible to anyone using the Internet. Computer scientist Michael K. Bergman is credited with coining the term deep web in 2001 as a search indexing term.The content of the deep web is hidden behind HTTP forms, and includes many very common uses such as web mail, online banking, and services that users must pay for, and which is protected by a paywall, such as video on demand, some online magazines and newspapers, among others.
The content of the deep web can be located and accessed by a direct URL or IP address, and may require a password or other security access past the public website page.
| 4
|
[
"World Wide Web",
"instance of",
"information system"
] |
The World Wide Web (WWW), commonly known as the Web, is an information system enabling documents and other web resources to be accessed over the Internet.Documents and downloadable media are made available to the network through web servers and can be accessed by programs such as web browsers. Servers and resources on the World Wide Web are identified and located through character strings called uniform resource locators (URLs). The original and still very common document type is a web page formatted in Hypertext Markup Language (HTML). This markup language supports plain text, images, embedded video and audio contents, and scripts (short programs) that implement complex user interaction. The HTML language also supports hyperlinks (embedded URLs) which provide immediate access to other web resources. Web navigation, or web surfing, is the common practice of following such hyperlinks across multiple websites. Web applications are web pages that function as application software. The information in the Web is transferred across the Internet using the Hypertext Transfer Protocol (HTTP).
Multiple web resources with a common theme and usually a common domain name make up a website. A single web server may provide multiple websites, while some websites, especially the most popular ones, may be provided by multiple servers. Website content is provided by a myriad of companies, organizations, government agencies, and individual users; and comprises an enormous amount of educational, entertainment, commercial, and government information.
The World Wide Web has become the world's dominant software platform. It is the primary tool billions of people worldwide use to interact with the Internet.The Web was invented by Tim Berners-Lee at CERN in 1989 and opened to the public in 1991. It was conceived as a "universal linked information system".
| 6
|
[
"World Wide Web",
"instance of",
"hypertext system"
] |
The World Wide Web (WWW), commonly known as the Web, is an information system enabling documents and other web resources to be accessed over the Internet.Documents and downloadable media are made available to the network through web servers and can be accessed by programs such as web browsers. Servers and resources on the World Wide Web are identified and located through character strings called uniform resource locators (URLs). The original and still very common document type is a web page formatted in Hypertext Markup Language (HTML). This markup language supports plain text, images, embedded video and audio contents, and scripts (short programs) that implement complex user interaction. The HTML language also supports hyperlinks (embedded URLs) which provide immediate access to other web resources. Web navigation, or web surfing, is the common practice of following such hyperlinks across multiple websites. Web applications are web pages that function as application software. The information in the Web is transferred across the Internet using the Hypertext Transfer Protocol (HTTP).
Multiple web resources with a common theme and usually a common domain name make up a website. A single web server may provide multiple websites, while some websites, especially the most popular ones, may be provided by multiple servers. Website content is provided by a myriad of companies, organizations, government agencies, and individual users; and comprises an enormous amount of educational, entertainment, commercial, and government information.
The World Wide Web has become the world's dominant software platform. It is the primary tool billions of people worldwide use to interact with the Internet.The Web was invented by Tim Berners-Lee at CERN in 1989 and opened to the public in 1991. It was conceived as a "universal linked information system".Website
A website is a collection of related web resources including web pages, multimedia content, typically identified with a common domain name, and published on at least one web server. Notable examples are wikipedia.org, google.com, and amazon.com.
A website may be accessible via a public Internet Protocol (IP) network, such as the Internet, or a private local area network (LAN), by referencing a uniform resource locator (URL) that identifies the site.
Websites can have many functions and can be used in various fashions; a website can be a personal website, a corporate website for a company, a government website, an organization website, etc. Websites are typically dedicated to a particular topic or purpose, ranging from entertainment and social networking to providing news and education. All publicly accessible websites collectively constitute the World Wide Web, while private websites, such as a company's website for its employees, are typically a part of an intranet.
Web pages, which are the building blocks of websites, are documents, typically composed in plain text interspersed with formatting instructions of Hypertext Markup Language (HTML, XHTML). They may incorporate elements from other websites with suitable markup anchors. Web pages are accessed and transported with the Hypertext Transfer Protocol (HTTP), which may optionally employ encryption (HTTP Secure, HTTPS) to provide security and privacy for the user. The user's application, often a web browser, renders the page content according to its HTML markup instructions onto a display terminal.
Hyperlinking between web pages conveys to the reader the site structure and guides the navigation of the site, which often starts with a home page containing a directory of the site web content. Some websites require user registration or subscription to access content. Examples of subscription websites include many business sites, news websites, academic journal websites, gaming websites, file-sharing websites, message boards, web-based email, social networking websites, websites providing real-time price quotations for different types of markets, as well as sites providing various other services. End users can access websites on a range of devices, including desktop and laptop computers, tablet computers, smartphones and smart TVs.
| 15
|
[
"HTTP",
"discoverer or inventor",
"Tim Berners-Lee"
] |
History
The term hypertext was coined by Ted Nelson in 1965 in the Xanadu Project, which was in turn inspired by Vannevar Bush's 1930s vision of the microfilm-based information retrieval and management "memex" system described in his 1945 essay "As We May Think". Tim Berners-Lee and his team at CERN are credited with inventing the original HTTP, along with HTML and the associated technology for a web server and a client user interface called web browser. Berners-Lee designed HTTP in order to help with the adoption of his other idea: the "WorldWideWeb" project, which was first proposed in 1989, now known as the World Wide Web.
The first web server went live in 1990. The protocol used had only one method, namely GET, which would request a page from a server. The response from the server was always an HTML page.
| 0
|
[
"HTTP",
"different from",
"File Transfer Protocol"
] |
The Hypertext Transfer Protocol (HTTP) is an application layer protocol in the Internet protocol suite model for distributed, collaborative, hypermedia information systems. HTTP is the foundation of data communication for the World Wide Web, where hypertext documents include hyperlinks to other resources that the user can easily access, for example by a mouse click or by tapping the screen in a web browser.
Development of HTTP was initiated by Tim Berners-Lee at CERN in 1989 and summarized in a simple document describing the behavior of a client and a server using the first HTTP version, named 0.9. That version was subsequently developed, eventually becoming the public 1.0.Development of early HTTP Requests for Comments (RFCs) started a few years later in a coordinated effort by the Internet Engineering Task Force (IETF) and the World Wide Web Consortium (W3C), with work later moving to the IETF.
HTTP/1 was finalized and fully documented (as version 1.0) in 1996. It evolved (as version 1.1) in 1997 and then its specifications were updated in 1999, 2014, and 2022.Its secure variant named HTTPS is used by more than 80% of websites.HTTP/2, published in 2015, provides a more efficient expression of HTTP's semantics "on the wire". As of April 2023, it is used by 39% of websites and supported by almost all web browsers (over 97% of users). It is also supported by major web servers over Transport Layer Security (TLS) using an Application-Layer Protocol Negotiation (ALPN) extension where TLS 1.2 or newer is required.HTTP/3, the successor to HTTP/2, was published in 2022. It is now used by over 25% of websites and is supported by many web browsers (over 75% of users). HTTP/3 uses QUIC instead of TCP for the underlying transport protocol. Like HTTP/2, it does not obsolesce previous major versions of the protocol. Support for HTTP/3 was added to Cloudflare and Google Chrome first, and is also enabled in Firefox. HTTP/3 has lower latency for real-world web pages, if enabled on the server, load faster than with HTTP/2, and even faster than HTTP/1.1, in some cases over 3× faster than HTTP/1.1 (which is still commonly only enabled).Technical overview
HTTP functions as a request–response protocol in the client–server model. A web browser, for example, may be the client whereas a process, named web server, running on a computer hosting one or more websites may be the server. The client submits an HTTP request message to the server. The server, which provides resources such as HTML files and other content or performs other functions on behalf of the client, returns a response message to the client. The response contains completion status information about the request and may also contain requested content in its message body.
A web browser is an example of a user agent (UA). Other types of user agent include the indexing software used by search providers (web crawlers), voice browsers, mobile apps, and other software that accesses, consumes, or displays web content.
HTTP is designed to permit intermediate network elements to improve or enable communications between clients and servers. High-traffic websites often benefit from web cache servers that deliver content on behalf of upstream servers to improve response time. Web browsers cache previously accessed web resources and reuse them, whenever possible, to reduce network traffic. HTTP proxy servers at private network boundaries can facilitate communication for clients without a globally routable address, by relaying messages with external servers.
To allow intermediate HTTP nodes (proxy servers, web caches, etc.) to accomplish their functions, some of the HTTP headers (found in HTTP requests/responses) are managed hop-by-hop whereas other HTTP headers are managed end-to-end (managed only by the source client and by the target web server).
HTTP is an application layer protocol designed within the framework of the Internet protocol suite. Its definition presumes an underlying and reliable transport layer protocol, thus Transmission Control Protocol (TCP) is commonly used. However, HTTP can be adapted to use unreliable protocols such as the User Datagram Protocol (UDP), for example in HTTPU and Simple Service Discovery Protocol (SSDP).
HTTP resources are identified and located on the network by Uniform Resource Locators (URLs), using the Uniform Resource Identifiers (URI's) schemes http and https. As defined in RFC 3986, URIs are encoded as hyperlinks in HTML documents, so as to form interlinked hypertext documents.
In HTTP/1.0 a separate connection to the same server is made for every resource request.In HTTP/1.1 instead a TCP connection can be reused to make multiple resource requests (i.e. of HTML pages, frames, images, scripts, stylesheets, etc.).HTTP/1.1 communications therefore experience less latency as the establishment of TCP connections presents considerable overhead, specially under high traffic conditions.HTTP/2 is a revision of previous HTTP/1.1 in order to maintain the same client–server model and the same protocol methods but with these differences in order:
| 6
|
[
"HTTP",
"instance of",
"computer network protocol"
] |
Technical overview
HTTP functions as a request–response protocol in the client–server model. A web browser, for example, may be the client whereas a process, named web server, running on a computer hosting one or more websites may be the server. The client submits an HTTP request message to the server. The server, which provides resources such as HTML files and other content or performs other functions on behalf of the client, returns a response message to the client. The response contains completion status information about the request and may also contain requested content in its message body.
A web browser is an example of a user agent (UA). Other types of user agent include the indexing software used by search providers (web crawlers), voice browsers, mobile apps, and other software that accesses, consumes, or displays web content.
HTTP is designed to permit intermediate network elements to improve or enable communications between clients and servers. High-traffic websites often benefit from web cache servers that deliver content on behalf of upstream servers to improve response time. Web browsers cache previously accessed web resources and reuse them, whenever possible, to reduce network traffic. HTTP proxy servers at private network boundaries can facilitate communication for clients without a globally routable address, by relaying messages with external servers.
To allow intermediate HTTP nodes (proxy servers, web caches, etc.) to accomplish their functions, some of the HTTP headers (found in HTTP requests/responses) are managed hop-by-hop whereas other HTTP headers are managed end-to-end (managed only by the source client and by the target web server).
HTTP is an application layer protocol designed within the framework of the Internet protocol suite. Its definition presumes an underlying and reliable transport layer protocol, thus Transmission Control Protocol (TCP) is commonly used. However, HTTP can be adapted to use unreliable protocols such as the User Datagram Protocol (UDP), for example in HTTPU and Simple Service Discovery Protocol (SSDP).
HTTP resources are identified and located on the network by Uniform Resource Locators (URLs), using the Uniform Resource Identifiers (URI's) schemes http and https. As defined in RFC 3986, URIs are encoded as hyperlinks in HTML documents, so as to form interlinked hypertext documents.
In HTTP/1.0 a separate connection to the same server is made for every resource request.In HTTP/1.1 instead a TCP connection can be reused to make multiple resource requests (i.e. of HTML pages, frames, images, scripts, stylesheets, etc.).HTTP/1.1 communications therefore experience less latency as the establishment of TCP connections presents considerable overhead, specially under high traffic conditions.HTTP/2 is a revision of previous HTTP/1.1 in order to maintain the same client–server model and the same protocol methods but with these differences in order:
| 18
|
[
"HTTP",
"has part(s)",
"HTTP response"
] |
Response syntax
A server sends response messages to the client, which consist of:
a status line, consisting of the protocol version, a space, the response status code, another space, a possibly empty reason phrase, a carriage return and a line feed, e.g.:HTTP/1.1 200 OKzero or more response header fields, each consisting of the case-insensitive field name, a colon, optional leading whitespace, the field value, an optional trailing whitespace and ending with a carriage return and a line feed, e.g.:Content-Type: text/html
| 28
|
[
"Semantic Web",
"discoverer or inventor",
"Tim Berners-Lee"
] |
Background
The concept of the semantic network model was formed in the early 1960s by researchers such as the cognitive scientist Allan M. Collins, linguist M. Ross Quillian and psychologist Elizabeth F. Loftus as a form to represent semantically structured knowledge. When applied in the context of the modern internet, it extends the network of hyperlinked human-readable web pages by inserting machine-readable metadata about pages and how they are related to each other. This enables automated agents to access the Web more intelligently and perform more tasks on behalf of users. The term "Semantic Web" was coined by Tim Berners-Lee, the inventor of the World Wide Web and director of the World Wide Web Consortium ("W3C"), which oversees the development of proposed Semantic Web standards. He defines the Semantic Web as "a web of data that can be processed directly and indirectly by machines".
Many of the technologies proposed by the W3C already existed before they were positioned under the W3C umbrella. These are used in various contexts, particularly those dealing with information that encompasses a limited and defined domain, and where sharing data is a common necessity, such as scientific research or data exchange among businesses. In addition, other technologies with similar goals have emerged, such as microformats.
| 0
|
[
"Semantic Web",
"subclass of",
"World Wide Web"
] |
The Semantic Web, sometimes known as Web 3.0 (not to be confused with Web3), is an extension of the World Wide Web through standards set by the World Wide Web Consortium (W3C). The goal of the Semantic Web is to make Internet data machine-readable.
To enable the encoding of semantics with the data, technologies such as Resource Description Framework (RDF) and Web Ontology Language (OWL) are used. These technologies are used to formally represent metadata. For example, ontology can describe concepts, relationships between entities, and categories of things. These embedded semantics offer significant advantages such as reasoning over data and operating with heterogeneous data sources.These standards promote common data formats and exchange protocols on the Web, fundamentally the RDF. According to the W3C, "The Semantic Web provides a common framework that allows data to be shared and reused across application, enterprise, and community boundaries." The Semantic Web is therefore regarded as an integrator across different content and information applications and systems.
The term was coined by Tim Berners-Lee for a web of data (or data web) that can be processed by machines—that is, one in which much of the meaning is machine-readable. While its critics have questioned its feasibility, proponents argue that applications in library and information science, industry, biology and human sciences research have already proven the validity of the original concept.Berners-Lee originally expressed his vision of the Semantic Web in 1999 as follows:
| 1
|
[
"Semantic Web",
"uses",
"Extensible Markup Language"
] |
Semantic Web solutions
The Semantic Web takes the solution further. It involves publishing in languages specifically designed for data: Resource Description Framework (RDF), Web Ontology Language (OWL), and Extensible Markup Language (XML). HTML describes documents and the links between them. RDF, OWL, and XML, by contrast, can describe arbitrary things such as people, meetings, or airplane parts.
These technologies are combined in order to provide descriptions that supplement or replace the content of Web documents. Thus, content may manifest itself as descriptive data stored in Web-accessible databases, or as markup within documents (particularly, in Extensible HTML (XHTML) interspersed with XML, or, more often, purely in XML, with layout or rendering cues stored separately). The machine-readable descriptions enable content managers to add meaning to the content, i.e., to describe the structure of the knowledge we have about that content. In this way, a machine can process knowledge itself, instead of text, using processes similar to human deductive reasoning and inference, thereby obtaining more meaningful results and helping computers to perform automated information gathering and research.
An example of a tag that would be used in a non-semantic web page:
| 2
|
[
"Semantic Web",
"uses",
"SPARQL"
] |
Resource Description Framework (RDF), a general method for describing information
RDF Schema (RDFS)
Simple Knowledge Organization System (SKOS)
SPARQL, an RDF query language
Notation3 (N3), designed with human readability in mind
N-Triples, a format for storing and transmitting data
Turtle (Terse RDF Triple Language)
Web Ontology Language (OWL), a family of knowledge representation languages
Rule Interchange Format (RIF), a framework of web rule language dialects supporting rule interchange on the Web
JavaScript Object Notation for Linked Data (JSON-LD), a JSON-based method to describe data
ActivityPub, a generic way for client and server to communicate with each other. This is used by the popular decentralized social network Mastodon.
The Semantic Web Stack illustrates the architecture of the Semantic Web. The functions and relationships of the components can be summarized as follows:
XML provides an elemental syntax for content structure within documents, yet associates no semantics with the meaning of the content contained within. XML is not at present a necessary component of Semantic Web technologies in most cases, as alternative syntaxes exist, such as Turtle. Turtle is a de facto standard, but has not been through a formal standardization process.
XML Schema is a language for providing and restricting the structure and content of elements contained within XML documents.
RDF is a simple language for expressing data models, which refer to objects ("web resources") and their relationships. An RDF-based model can be represented in a variety of syntaxes, e.g., RDF/XML, N3, Turtle, and RDFa. RDF is a fundamental standard of the Semantic Web.
RDF Schema extends RDF and is a vocabulary for describing properties and classes of RDF-based resources, with semantics for generalized-hierarchies of such properties and classes.
OWL adds more vocabulary for describing properties and classes: among others, relations between classes (e.g. disjointness), cardinality (e.g. "exactly one"), equality, richer typing of properties, characteristics of properties (e.g. symmetry), and enumerated classes.
SPARQL is a protocol and query language for semantic web data sources.
RIF is the W3C Rule Interchange Format. It's an XML language for expressing Web rules that computers can execute. RIF provides multiple versions, called dialects. It includes a RIF Basic Logic Dialect (RIF-BLD) and RIF Production Rules Dialect (RIF PRD).Applications
The intent is to enhance the usability and usefulness of the Web and its interconnected resources by creating semantic web services, such as:Servers that expose existing data systems using the RDF and SPARQL standards. Many converters to RDF exist from different applications. Relational databases are an important source. The semantic web server attaches to the existing system without affecting its operation.
Documents "marked up" with semantic information (an extension of the HTML <meta> tags used in today's Web pages to supply information for Web search engines using web crawlers). This could be machine-understandable information about the human-understandable content of the document (such as the creator, title, description, etc.) or it could be purely metadata representing a set of facts (such as resources and services elsewhere on the site). Note that anything that can be identified with a Uniform Resource Identifier (URI) can be described, so the semantic web can reason about animals, people, places, ideas, etc. There are four semantic annotation formats that can be used in HTML documents; Microformat, RDFa, Microdata and JSON-LD. Semantic markup is often generated automatically, rather than manually.
Common metadata vocabularies (ontologies) and maps between vocabularies that allow document creators to know how to mark up their documents so that agents can use the information in the supplied metadata (so that Author in the sense of 'the Author of the page' will not be confused with Author in the sense of a book that is the subject of a book review).
Automated agents to perform tasks for users of the semantic web using this data.
Semantic translation
Web-based services (often with agents of their own) to supply information specifically to agents, for example, a Trust service that an agent could ask if some online store has a history of poor service or spamming.Such services could be useful to public search engines, or could be used for knowledge management within an organization. Business applications include:
| 3
|
[
"Semantic Web",
"uses",
"Resource Description Framework"
] |
The Semantic Web, sometimes known as Web 3.0 (not to be confused with Web3), is an extension of the World Wide Web through standards set by the World Wide Web Consortium (W3C). The goal of the Semantic Web is to make Internet data machine-readable.
To enable the encoding of semantics with the data, technologies such as Resource Description Framework (RDF) and Web Ontology Language (OWL) are used. These technologies are used to formally represent metadata. For example, ontology can describe concepts, relationships between entities, and categories of things. These embedded semantics offer significant advantages such as reasoning over data and operating with heterogeneous data sources.These standards promote common data formats and exchange protocols on the Web, fundamentally the RDF. According to the W3C, "The Semantic Web provides a common framework that allows data to be shared and reused across application, enterprise, and community boundaries." The Semantic Web is therefore regarded as an integrator across different content and information applications and systems.
The term was coined by Tim Berners-Lee for a web of data (or data web) that can be processed by machines—that is, one in which much of the meaning is machine-readable. While its critics have questioned its feasibility, proponents argue that applications in library and information science, industry, biology and human sciences research have already proven the validity of the original concept.Berners-Lee originally expressed his vision of the Semantic Web in 1999 as follows:Semantic Web solutions
The Semantic Web takes the solution further. It involves publishing in languages specifically designed for data: Resource Description Framework (RDF), Web Ontology Language (OWL), and Extensible Markup Language (XML). HTML describes documents and the links between them. RDF, OWL, and XML, by contrast, can describe arbitrary things such as people, meetings, or airplane parts.
These technologies are combined in order to provide descriptions that supplement or replace the content of Web documents. Thus, content may manifest itself as descriptive data stored in Web-accessible databases, or as markup within documents (particularly, in Extensible HTML (XHTML) interspersed with XML, or, more often, purely in XML, with layout or rendering cues stored separately). The machine-readable descriptions enable content managers to add meaning to the content, i.e., to describe the structure of the knowledge we have about that content. In this way, a machine can process knowledge itself, instead of text, using processes similar to human deductive reasoning and inference, thereby obtaining more meaningful results and helping computers to perform automated information gathering and research.
An example of a tag that would be used in a non-semantic web page:Components
The term "Semantic Web" is often used more specifically to refer to the formats and technologies that enable it. The collection, structuring and recovery of linked data are enabled by technologies that provide a formal description of concepts, terms, and relationships within a given knowledge domain. These technologies are specified as W3C standards and include:Resource Description Framework (RDF), a general method for describing information
RDF Schema (RDFS)
Simple Knowledge Organization System (SKOS)
SPARQL, an RDF query language
Notation3 (N3), designed with human readability in mind
N-Triples, a format for storing and transmitting data
Turtle (Terse RDF Triple Language)
Web Ontology Language (OWL), a family of knowledge representation languages
Rule Interchange Format (RIF), a framework of web rule language dialects supporting rule interchange on the Web
JavaScript Object Notation for Linked Data (JSON-LD), a JSON-based method to describe data
ActivityPub, a generic way for client and server to communicate with each other. This is used by the popular decentralized social network Mastodon.
The Semantic Web Stack illustrates the architecture of the Semantic Web. The functions and relationships of the components can be summarized as follows:
XML provides an elemental syntax for content structure within documents, yet associates no semantics with the meaning of the content contained within. XML is not at present a necessary component of Semantic Web technologies in most cases, as alternative syntaxes exist, such as Turtle. Turtle is a de facto standard, but has not been through a formal standardization process.
XML Schema is a language for providing and restricting the structure and content of elements contained within XML documents.
RDF is a simple language for expressing data models, which refer to objects ("web resources") and their relationships. An RDF-based model can be represented in a variety of syntaxes, e.g., RDF/XML, N3, Turtle, and RDFa. RDF is a fundamental standard of the Semantic Web.
RDF Schema extends RDF and is a vocabulary for describing properties and classes of RDF-based resources, with semantics for generalized-hierarchies of such properties and classes.
OWL adds more vocabulary for describing properties and classes: among others, relations between classes (e.g. disjointness), cardinality (e.g. "exactly one"), equality, richer typing of properties, characteristics of properties (e.g. symmetry), and enumerated classes.
SPARQL is a protocol and query language for semantic web data sources.
RIF is the W3C Rule Interchange Format. It's an XML language for expressing Web rules that computers can execute. RIF provides multiple versions, called dialects. It includes a RIF Basic Logic Dialect (RIF-BLD) and RIF Production Rules Dialect (RIF PRD).
| 4
|
[
"Semantic Web",
"uses",
"Uniform Resource Identifier"
] |
One of the advantages of using Uniform Resource Identifiers (URIs) is that they can be dereferenced using the HTTP protocol. According to the so-called Linked Open Data principles, such a dereferenced URI should result in a document that offers further data about the given URI. In this example, all URIs, both for edges and nodes (e.g. http://schema.org/Person, http://schema.org/birthPlace, http://www.wikidata.org/entity/Q1731) can be dereferenced and will result in further RDF graphs, describing the URI, e.g. that Dresden is a city in Germany, or that a person, in the sense of that URI, can be fictional.
The second graph shows the previous example, but now enriched with a few of the triples from the documents that result from dereferencing https://schema.org/Person (green edge) and https://www.wikidata.org/entity/Q1731 (blue edges).
Additionally to the edges given in the involved documents explicitly, edges can be automatically inferred: the tripleApplications
The intent is to enhance the usability and usefulness of the Web and its interconnected resources by creating semantic web services, such as:
| 5
|
[
"Semantic Web",
"instance of",
"information system"
] |
Future of applications
Tim O'Reilly, who coined the term Web 2.0, proposed a long-term vision of the Semantic Web as a web of data, where sophisticated applications are navigating and manipulating it. The data web transforms the World Wide Web from a distributed file system into a distributed database system.
| 6
|
[
"Semantic Web",
"has part(s)",
"linked data"
] |
The Semantic Web, sometimes known as Web 3.0 (not to be confused with Web3), is an extension of the World Wide Web through standards set by the World Wide Web Consortium (W3C). The goal of the Semantic Web is to make Internet data machine-readable.
To enable the encoding of semantics with the data, technologies such as Resource Description Framework (RDF) and Web Ontology Language (OWL) are used. These technologies are used to formally represent metadata. For example, ontology can describe concepts, relationships between entities, and categories of things. These embedded semantics offer significant advantages such as reasoning over data and operating with heterogeneous data sources.These standards promote common data formats and exchange protocols on the Web, fundamentally the RDF. According to the W3C, "The Semantic Web provides a common framework that allows data to be shared and reused across application, enterprise, and community boundaries." The Semantic Web is therefore regarded as an integrator across different content and information applications and systems.
The term was coined by Tim Berners-Lee for a web of data (or data web) that can be processed by machines—that is, one in which much of the meaning is machine-readable. While its critics have questioned its feasibility, proponents argue that applications in library and information science, industry, biology and human sciences research have already proven the validity of the original concept.Berners-Lee originally expressed his vision of the Semantic Web in 1999 as follows:Because of this metadata tagging and categorization, other computer systems that want to access and share this data can easily identify the relevant values.
With HTML and a tool to render it (perhaps web browser software, perhaps another user agent), one can create and present a page that lists items for sale. The HTML of this catalog page can make simple, document-level assertions such as "this document's title is 'Widget Superstore'", but there is no capability within the HTML itself to assert unambiguously that, for example, item number X586172 is an Acme Gizmo with a retail price of €199, or that it is a consumer product. Rather, HTML can only say that the span of text "X586172" is something that should be positioned near "Acme Gizmo" and "€199", etc. There is no way to say "this is a catalog" or even to establish that "Acme Gizmo" is a kind of title or that "€199" is a price. There is also no way to express that these pieces of information are bound together in describing a discrete item, distinct from other items perhaps listed on the page.
Semantic HTML refers to the traditional HTML practice of markup following intention, rather than specifying layout details directly. For example, the use of <em> denoting "emphasis" rather than <i>, which specifies italics. Layout details are left up to the browser, in combination with Cascading Style Sheets. But this practice falls short of specifying the semantics of objects such as items for sale or prices.
Microformats extend HTML syntax to create machine-readable semantic markup about objects including people, organizations, events and products. Similar initiatives include RDFa, Microdata and Schema.org.
| 7
|
[
"Semantic Web",
"has quality",
"linked data"
] |
Background
The concept of the semantic network model was formed in the early 1960s by researchers such as the cognitive scientist Allan M. Collins, linguist M. Ross Quillian and psychologist Elizabeth F. Loftus as a form to represent semantically structured knowledge. When applied in the context of the modern internet, it extends the network of hyperlinked human-readable web pages by inserting machine-readable metadata about pages and how they are related to each other. This enables automated agents to access the Web more intelligently and perform more tasks on behalf of users. The term "Semantic Web" was coined by Tim Berners-Lee, the inventor of the World Wide Web and director of the World Wide Web Consortium ("W3C"), which oversees the development of proposed Semantic Web standards. He defines the Semantic Web as "a web of data that can be processed directly and indirectly by machines".
Many of the technologies proposed by the W3C already existed before they were positioned under the W3C umbrella. These are used in various contexts, particularly those dealing with information that encompasses a limited and defined domain, and where sharing data is a common necessity, such as scientific research or data exchange among businesses. In addition, other technologies with similar goals have emerged, such as microformats.Tim Berners-Lee calls the resulting network of Linked Data the Giant Global Graph, in contrast to the HTML-based World Wide Web. Berners-Lee posits that if the past was document sharing, the future is data sharing. His answer to the question of "how" provides three points of instruction. One, a URL should point to the data. Two, anyone accessing the URL should get data back. Three, relationships in the data should point to additional URLs with data.Components
The term "Semantic Web" is often used more specifically to refer to the formats and technologies that enable it. The collection, structuring and recovery of linked data are enabled by technologies that provide a formal description of concepts, terms, and relationships within a given knowledge domain. These technologies are specified as W3C standards and include:
| 8
|
[
"Semantic Web",
"uses",
"linked data"
] |
The Semantic Web, sometimes known as Web 3.0 (not to be confused with Web3), is an extension of the World Wide Web through standards set by the World Wide Web Consortium (W3C). The goal of the Semantic Web is to make Internet data machine-readable.
To enable the encoding of semantics with the data, technologies such as Resource Description Framework (RDF) and Web Ontology Language (OWL) are used. These technologies are used to formally represent metadata. For example, ontology can describe concepts, relationships between entities, and categories of things. These embedded semantics offer significant advantages such as reasoning over data and operating with heterogeneous data sources.These standards promote common data formats and exchange protocols on the Web, fundamentally the RDF. According to the W3C, "The Semantic Web provides a common framework that allows data to be shared and reused across application, enterprise, and community boundaries." The Semantic Web is therefore regarded as an integrator across different content and information applications and systems.
The term was coined by Tim Berners-Lee for a web of data (or data web) that can be processed by machines—that is, one in which much of the meaning is machine-readable. While its critics have questioned its feasibility, proponents argue that applications in library and information science, industry, biology and human sciences research have already proven the validity of the original concept.Berners-Lee originally expressed his vision of the Semantic Web in 1999 as follows:Applications
The intent is to enhance the usability and usefulness of the Web and its interconnected resources by creating semantic web services, such as:Servers that expose existing data systems using the RDF and SPARQL standards. Many converters to RDF exist from different applications. Relational databases are an important source. The semantic web server attaches to the existing system without affecting its operation.
Documents "marked up" with semantic information (an extension of the HTML <meta> tags used in today's Web pages to supply information for Web search engines using web crawlers). This could be machine-understandable information about the human-understandable content of the document (such as the creator, title, description, etc.) or it could be purely metadata representing a set of facts (such as resources and services elsewhere on the site). Note that anything that can be identified with a Uniform Resource Identifier (URI) can be described, so the semantic web can reason about animals, people, places, ideas, etc. There are four semantic annotation formats that can be used in HTML documents; Microformat, RDFa, Microdata and JSON-LD. Semantic markup is often generated automatically, rather than manually.
Common metadata vocabularies (ontologies) and maps between vocabularies that allow document creators to know how to mark up their documents so that agents can use the information in the supplied metadata (so that Author in the sense of 'the Author of the page' will not be confused with Author in the sense of a book that is the subject of a book review).
Automated agents to perform tasks for users of the semantic web using this data.
Semantic translation
Web-based services (often with agents of their own) to supply information specifically to agents, for example, a Trust service that an agent could ask if some online store has a history of poor service or spamming.Such services could be useful to public search engines, or could be used for knowledge management within an organization. Business applications include:
| 9
|
[
"Semantic Web",
"uses",
"ontology"
] |
The Semantic Web, sometimes known as Web 3.0 (not to be confused with Web3), is an extension of the World Wide Web through standards set by the World Wide Web Consortium (W3C). The goal of the Semantic Web is to make Internet data machine-readable.
To enable the encoding of semantics with the data, technologies such as Resource Description Framework (RDF) and Web Ontology Language (OWL) are used. These technologies are used to formally represent metadata. For example, ontology can describe concepts, relationships between entities, and categories of things. These embedded semantics offer significant advantages such as reasoning over data and operating with heterogeneous data sources.These standards promote common data formats and exchange protocols on the Web, fundamentally the RDF. According to the W3C, "The Semantic Web provides a common framework that allows data to be shared and reused across application, enterprise, and community boundaries." The Semantic Web is therefore regarded as an integrator across different content and information applications and systems.
The term was coined by Tim Berners-Lee for a web of data (or data web) that can be processed by machines—that is, one in which much of the meaning is machine-readable. While its critics have questioned its feasibility, proponents argue that applications in library and information science, industry, biology and human sciences research have already proven the validity of the original concept.Berners-Lee originally expressed his vision of the Semantic Web in 1999 as follows:Semantic Web solutions
The Semantic Web takes the solution further. It involves publishing in languages specifically designed for data: Resource Description Framework (RDF), Web Ontology Language (OWL), and Extensible Markup Language (XML). HTML describes documents and the links between them. RDF, OWL, and XML, by contrast, can describe arbitrary things such as people, meetings, or airplane parts.
These technologies are combined in order to provide descriptions that supplement or replace the content of Web documents. Thus, content may manifest itself as descriptive data stored in Web-accessible databases, or as markup within documents (particularly, in Extensible HTML (XHTML) interspersed with XML, or, more often, purely in XML, with layout or rendering cues stored separately). The machine-readable descriptions enable content managers to add meaning to the content, i.e., to describe the structure of the knowledge we have about that content. In this way, a machine can process knowledge itself, instead of text, using processes similar to human deductive reasoning and inference, thereby obtaining more meaningful results and helping computers to perform automated information gathering and research.
An example of a tag that would be used in a non-semantic web page:Components
The term "Semantic Web" is often used more specifically to refer to the formats and technologies that enable it. The collection, structuring and recovery of linked data are enabled by technologies that provide a formal description of concepts, terms, and relationships within a given knowledge domain. These technologies are specified as W3C standards and include:Resource Description Framework (RDF), a general method for describing information
RDF Schema (RDFS)
Simple Knowledge Organization System (SKOS)
SPARQL, an RDF query language
Notation3 (N3), designed with human readability in mind
N-Triples, a format for storing and transmitting data
Turtle (Terse RDF Triple Language)
Web Ontology Language (OWL), a family of knowledge representation languages
Rule Interchange Format (RIF), a framework of web rule language dialects supporting rule interchange on the Web
JavaScript Object Notation for Linked Data (JSON-LD), a JSON-based method to describe data
ActivityPub, a generic way for client and server to communicate with each other. This is used by the popular decentralized social network Mastodon.
The Semantic Web Stack illustrates the architecture of the Semantic Web. The functions and relationships of the components can be summarized as follows:
XML provides an elemental syntax for content structure within documents, yet associates no semantics with the meaning of the content contained within. XML is not at present a necessary component of Semantic Web technologies in most cases, as alternative syntaxes exist, such as Turtle. Turtle is a de facto standard, but has not been through a formal standardization process.
XML Schema is a language for providing and restricting the structure and content of elements contained within XML documents.
RDF is a simple language for expressing data models, which refer to objects ("web resources") and their relationships. An RDF-based model can be represented in a variety of syntaxes, e.g., RDF/XML, N3, Turtle, and RDFa. RDF is a fundamental standard of the Semantic Web.
RDF Schema extends RDF and is a vocabulary for describing properties and classes of RDF-based resources, with semantics for generalized-hierarchies of such properties and classes.
OWL adds more vocabulary for describing properties and classes: among others, relations between classes (e.g. disjointness), cardinality (e.g. "exactly one"), equality, richer typing of properties, characteristics of properties (e.g. symmetry), and enumerated classes.
SPARQL is a protocol and query language for semantic web data sources.
RIF is the W3C Rule Interchange Format. It's an XML language for expressing Web rules that computers can execute. RIF provides multiple versions, called dialects. It includes a RIF Basic Logic Dialect (RIF-BLD) and RIF Production Rules Dialect (RIF PRD).Research activities on corporate applications
The first research group explicitly focusing on the Corporate Semantic Web was the ACACIA team at INRIA-Sophia-Antipolis, founded in 2002. Results of their work include the RDF(S) based Corese search engine, and the application of semantic web technology in the realm of distributed artificial intelligence for knowledge management (e.g. ontologies and multi-agent systems for corporate semantic Web) and E-learning.Since 2008, the Corporate Semantic Web research group, located at the Free University of Berlin, focuses on building blocks: Corporate Semantic Search, Corporate Semantic Collaboration, and Corporate Ontology Engineering.Ontology engineering research includes the question of how to involve non-expert users in creating ontologies and semantically annotated content and for extracting explicit knowledge from the interaction of users within enterprises.
| 12
|
[
"Semantic Web",
"uses",
"semantic data model"
] |
The Semantic Web, sometimes known as Web 3.0 (not to be confused with Web3), is an extension of the World Wide Web through standards set by the World Wide Web Consortium (W3C). The goal of the Semantic Web is to make Internet data machine-readable.
To enable the encoding of semantics with the data, technologies such as Resource Description Framework (RDF) and Web Ontology Language (OWL) are used. These technologies are used to formally represent metadata. For example, ontology can describe concepts, relationships between entities, and categories of things. These embedded semantics offer significant advantages such as reasoning over data and operating with heterogeneous data sources.These standards promote common data formats and exchange protocols on the Web, fundamentally the RDF. According to the W3C, "The Semantic Web provides a common framework that allows data to be shared and reused across application, enterprise, and community boundaries." The Semantic Web is therefore regarded as an integrator across different content and information applications and systems.
The term was coined by Tim Berners-Lee for a web of data (or data web) that can be processed by machines—that is, one in which much of the meaning is machine-readable. While its critics have questioned its feasibility, proponents argue that applications in library and information science, industry, biology and human sciences research have already proven the validity of the original concept.Berners-Lee originally expressed his vision of the Semantic Web in 1999 as follows:Applications
The intent is to enhance the usability and usefulness of the Web and its interconnected resources by creating semantic web services, such as:
| 13
|
[
"WorldWideWeb",
"discoverer or inventor",
"Tim Berners-Lee"
] |
History
Tim Berners-Lee wrote what would become known as WorldWideWeb on a NeXT Computer during the second half of 1990, while working for CERN, a European nuclear research agency. The first edition was completed "some time before" 25 December 1990, according to Berners-Lee, after two months of development. The browser was announced on the newsgroups and became available to the general public in August 1991. By this time, several others, including Bernd Pollermann, Robert Cailliau, Jean-François Groff, and visiting undergraduate student Nicola Pellow – who later wrote the Line Mode Browser – were involved in the project.Berners-Lee considered different names for his new application, including The Mine of Information and The Information Mesh, before publicly launching the WorldWideWeb browser in 1991. When a new version was released in 1994, it was renamed Nexus Browser, in order to differentiate between the software (WorldWideWeb) and the World Wide Web.The team created so called "passive browsers" which do not have the ability to edit because it was hard to port this feature from the NeXT system to other operating systems. Porting to the X Window System was not possible as nobody on the team had experience with the X Window System.Berners-Lee and Groff later adapted many of WorldWideWeb's components into a C programming language version, creating the libwww API.A number of early browsers appeared, notably ViolaWWW. They were all eclipsed by Mosaic in terms of popularity, which by 1993 had replaced the WorldWideWeb program. Those involved in its creation had moved on to other tasks, such as defining standards and guidelines for the further development of the World Wide Web (e.g. HTML, various communication protocols).On 30 April 1993, the CERN directorate released the source code of WorldWideWeb into the public domain. Several versions of the software are still available on the web in various states. Berners-Lee initially considered releasing it under the GNU General Public License, but after hearing rumors that companies might balk at the concept if any licensing issues were involved, he eventually opted to release it into the public domain.
| 0
|
[
"WorldWideWeb",
"instance of",
"web browser"
] |
WorldWideWeb (later renamed Nexus to avoid confusion between the software and the World Wide Web) is the first web browser and web page editor. It was discontinued in 1994. It was the first WYSIWYG HTML editor.
The source code was released into the public domain on 30 April 1993. Some of the code still resides on Tim Berners-Lee's NeXT Computer in the CERN museum and has not been recovered due to the computer's status as a historical artifact. To coincide with the 20th anniversary of the research center giving the web to the world, a project began in 2013 at CERN to preserve this original hardware and software associated with the birth of the Web.
| 3
|
[
"WorldWideWeb",
"instance of",
"HTML editor"
] |
WorldWideWeb (later renamed Nexus to avoid confusion between the software and the World Wide Web) is the first web browser and web page editor. It was discontinued in 1994. It was the first WYSIWYG HTML editor.
The source code was released into the public domain on 30 April 1993. Some of the code still resides on Tim Berners-Lee's NeXT Computer in the CERN museum and has not been recovered due to the computer's status as a historical artifact. To coincide with the 20th anniversary of the research center giving the web to the world, a project began in 2013 at CERN to preserve this original hardware and software associated with the birth of the Web.
| 8
|
[
"Google Takeout",
"developer",
"Google"
] |
Google Takeout, also known as Download Your Data, is a project by the Google Data Liberation Front that allows users of Google products, such as YouTube and Gmail, to export their data to a downloadable archive file.The user can select to export all of the available services or choose services from the above list. Takeout will then process the request and put all the files into a zip file. Takeout then optionally sends an email notification that the export is completed, at which point the user can download the archive from the downloads section of the website. The zip file contains a separate folder for each service that was selected for export.
| 1
|
[
"Google Takeout",
"instance of",
"project"
] |
Google Takeout, also known as Download Your Data, is a project by the Google Data Liberation Front that allows users of Google products, such as YouTube and Gmail, to export their data to a downloadable archive file.
| 3
|
[
"Advanced Power Management",
"discoverer or inventor",
"Intel"
] |
Advanced power management (APM) is an API developed by Intel and Microsoft and released in 1992 which enables an operating system running an IBM-compatible personal computer to work with the BIOS (part of the computer's firmware) to achieve power management.
Revision 1.2 was the last version of the APM specification, released in 1996. ACPI is the successor to APM. Microsoft dropped support for APM in Windows Vista. The Linux kernel still mostly supports APM, though support for APM CPU idle was dropped in version 3.0.
| 0
|
[
"Impressionism",
"followed by",
"post-impressionism"
] |
Impressionism emerged in France at the same time that a number of other painters, including the Italian artists known as the Macchiaioli, and Winslow Homer in the United States, were also exploring plein-air painting. The Impressionists, however, developed new techniques specific to the style. Encompassing what its adherents argued was a different way of seeing, it is an art of immediacy and movement, of candid poses and compositions, of the play of light expressed in a bright and varied use of colour.
The public, at first hostile, gradually came to believe that the Impressionists had captured a fresh and original vision, even if the art critics and art establishment disapproved of the new style. By recreating the sensation in the eye that views the subject, rather than delineating the details of the subject, and by creating a welter of techniques and forms, Impressionism is a precursor of various painting styles, including Neo-Impressionism, Post-Impressionism, Fauvism, and Cubism.
| 2
|
[
"Impressionism",
"named after",
"Impression, Sunrise"
] |
Impressionism was a 19th-century art movement characterized by relatively small, thin, yet visible brush strokes, open composition, emphasis on accurate depiction of light in its changing qualities (often accentuating the effects of the passage of time), ordinary subject matter, unusual visual angles, and inclusion of movement as a crucial element of human perception and experience. Impressionism originated with a group of Paris-based artists whose independent exhibitions brought them to prominence during the 1870s and 1880s.
The Impressionists faced harsh opposition from the conventional art community in France. The name of the style derives from the title of a Claude Monet work, Impression, soleil levant (Impression, Sunrise), which provoked the critic Louis Leroy to coin the term in a satirical review published in the Parisian newspaper Le Charivari. The development of Impressionism in the visual arts was soon followed by analogous styles in other media that became known as impressionist music and impressionist literature.
| 5
|
[
"Impressionism",
"instance of",
"art style"
] |
Impressionism emerged in France at the same time that a number of other painters, including the Italian artists known as the Macchiaioli, and Winslow Homer in the United States, were also exploring plein-air painting. The Impressionists, however, developed new techniques specific to the style. Encompassing what its adherents argued was a different way of seeing, it is an art of immediacy and movement, of candid poses and compositions, of the play of light expressed in a bright and varied use of colour.
The public, at first hostile, gradually came to believe that the Impressionists had captured a fresh and original vision, even if the art critics and art establishment disapproved of the new style. By recreating the sensation in the eye that views the subject, rather than delineating the details of the subject, and by creating a welter of techniques and forms, Impressionism is a precursor of various painting styles, including Neo-Impressionism, Post-Impressionism, Fauvism, and Cubism.
| 8
|
[
"Impressionism",
"instance of",
"painting movement"
] |
Impressionism emerged in France at the same time that a number of other painters, including the Italian artists known as the Macchiaioli, and Winslow Homer in the United States, were also exploring plein-air painting. The Impressionists, however, developed new techniques specific to the style. Encompassing what its adherents argued was a different way of seeing, it is an art of immediacy and movement, of candid poses and compositions, of the play of light expressed in a bright and varied use of colour.
The public, at first hostile, gradually came to believe that the Impressionists had captured a fresh and original vision, even if the art critics and art establishment disapproved of the new style. By recreating the sensation in the eye that views the subject, rather than delineating the details of the subject, and by creating a welter of techniques and forms, Impressionism is a precursor of various painting styles, including Neo-Impressionism, Post-Impressionism, Fauvism, and Cubism.
| 15
|
[
"Io (moon)",
"part of",
"Galilean moons"
] |
Orbit and rotation
Io orbits Jupiter at a distance of 421,700 km (262,000 mi) from Jupiter's center and 350,000 km (217,000 mi) from its cloudtops. It is the innermost of the Galilean satellites of Jupiter, its orbit lying between those of Thebe and Europa. Including Jupiter's inner satellites, Io is the fifth moon out from Jupiter. It takes Io about 42.5 hours (1.77 days) to complete one orbit around Jupiter (fast enough for its motion to be observed over a single night of observation). Io is in a 2:1 mean-motion orbital resonance with Europa and a 4:1 mean-motion orbital resonance with Ganymede, completing two orbits of Jupiter for every one orbit completed by Europa, and four orbits for every one completed by Ganymede. This resonance helps maintain Io's orbital eccentricity (0.0041), which in turn provides the primary heating source for its geologic activity. Without this forced eccentricity, Io's orbit would circularize through tidal dissipation, leading to a less geologically active world.Like the other Galilean satellites and the Moon, Io rotates synchronously with its orbital period, keeping one face nearly pointed toward Jupiter. This synchrony provides the definition for Io's longitude system. Io's prime meridian intersects the equator at the sub-Jovian point. The side of Io that always faces Jupiter is known as the subjovian hemisphere, whereas the side that always faces away is known as the antijovian hemisphere. The side of Io that always faces in the direction that Io travels in its orbit is known as the leading hemisphere, whereas the side that always faces in the opposite direction is known as the trailing hemisphere.From the surface of Io, Jupiter would subtend an arc of 19.5°, making Jupiter appear 39 times the apparent diameter of Earth's Moon.
| 5
|
[
"Io (moon)",
"instance of",
"moon of Jupiter"
] |
Future missions
There are two forthcoming missions planned for the Jovian system. The Jupiter Icy Moon Explorer (JUICE) is a planned European Space Agency mission to the Jovian system that is intended to end up in Ganymede orbit. JUICE is scheduled for launch in 2023, with arrival at Jupiter planned for July 2031. JUICE will not fly by Io, but it will use its instruments, such as a narrow-angle camera, to monitor Io's volcanic activity and measure its surface composition during the two-year Jupiter-tour phase of the mission prior to Ganymede orbit insertion. Europa Clipper is a planned NASA mission to the Jovian system focused on Jupiter's moon Europa. Like JUICE, Europa Clipper will not perform any flybys of Io, but distant volcano monitoring is likely. Europa Clipper has a planned launch in 2024 with an arrival at Jupiter in 2030.The Io Volcano Observer (IVO) was a proposal to NASA for a low-cost, Discovery-class mission selected for a Phase A study along with three other missions in 2020. IVO would launch in January 2029 and perform ten flybys of Io while in orbit around Jupiter beginning in the early 2030s. However, the Venus missions DAVINCI+ and VERITAS were selected in favor of those.
| 9
|
[
"Callisto (moon)",
"discoverer or inventor",
"Galileo Galilei"
] |
History
Discovery
Callisto was discovered independently by Simon Marius and Galileo Galilei in 1610, along with the three other large Jovian moons—Ganymede, Io, and Europa.
| 0
|
[
"Callisto (moon)",
"named after",
"Kallisto"
] |
Name
Callisto is named after one of Zeus's many lovers or other sexual partners in Greek mythology. Callisto was a nymph (or, according to some sources, the daughter of Lycaon) who was associated with the goddess of the hunt, Artemis. The name was suggested by Simon Marius soon after Callisto's discovery. Marius attributed the suggestion to Johannes Kepler.
Jupiter is much blamed by the poets on account of his irregular loves. Three maidens are especially mentioned as having been clandestinely courted by Jupiter with success. Io, daughter of the River Inachus, Callisto of Lycaon, Europa of Agenor. Then there was Ganymede, the handsome son of King Tros, whom Jupiter, having taken the form of an eagle, transported to heaven on his back, as poets fabulously tell... I think, therefore, that I shall not have done amiss if the First is called by me Io, the Second Europa, the Third, on account of its majesty of light, Ganymede, the Fourth Callisto...
However, the names of the Galilean satellites fell into disfavor for a considerable time, and were not revived in common use until the mid-20th century. In much of the earlier astronomical literature, Callisto is referred to by its Roman numeral designation, a system introduced by Galileo, as Jupiter IV or as "the fourth satellite of Jupiter".There's no established English adjectival form of the name. The adjectival form of Greek Καλλιστῴ Kallistōi is Καλλιστῴος Kallistōi-os, from which one might expect Latin Callistōius and English *Callistóian (with 5 syllables), parallel to Sapphóian (4 syllables) for Sapphōi and Letóian for Lētōi. However, the iota subscript is often omitted from such Greek names (cf. Inóan from Īnōi and Argóan from Argōi), and indeed the analogous form Callistoan is found.
In Virgil, a second oblique stem appears in Latin: Callistōn-, but the corresponding Callistonian has rarely appeared in English. One also sees ad hoc forms, such as Callistan, Callistian and Callistean.
| 8
|
[
"Ganymede (moon)",
"part of",
"Galilean moons"
] |
Orbit and rotation
Ganymede orbits Jupiter at a distance of 1,070,400 kilometres (665,100 mi), third among the Galilean satellites, and completes a revolution every seven days and three hours. Like most known moons, Ganymede is tidally locked, with one side always facing toward the planet, hence its day is also seven days and three hours. Its orbit is very slightly eccentric and inclined to the Jovian equator, with the eccentricity and inclination changing quasi-periodically due to solar and planetary gravitational perturbations on a timescale of centuries. The ranges of change are 0.0009–0.0022 and 0.05–0.32°, respectively. These orbital variations cause the axial tilt (the angle between rotational and orbital axes) to vary between 0 and 0.33°.Ganymede participates in orbital resonances with Europa and Io: for every orbit of Ganymede, Europa orbits twice and Io orbits four times. Conjunctions (alignment on the same side of Jupiter) between Io and Europa occur when Io is at periapsis and Europa at apoapsis. Conjunctions between Europa and Ganymede occur when Europa is at periapsis. The longitudes of the Io–Europa and Europa–Ganymede conjunctions change with the same rate, making triple conjunctions impossible. Such a complicated resonance is called the Laplace resonance.
The current Laplace resonance is unable to pump the orbital eccentricity of Ganymede to a higher value. The value of about 0.0013 is probably a remnant from a previous epoch, when such pumping was possible. The Ganymedian orbital eccentricity is somewhat puzzling; if it is not pumped now it should have decayed long ago due to the tidal dissipation in the interior of Ganymede. This means that the last episode of the eccentricity excitation happened only several hundred million years ago. Because Ganymede's orbital eccentricity is relatively low—on average 0.0015—tidal heating is negligible now. However, in the past Ganymede may have passed through one or more Laplace-like resonances that were able to pump the orbital eccentricity to a value as high as 0.01–0.02. This probably caused a significant tidal heating of the interior of Ganymede; the formation of the grooved terrain may be a result of one or more heating episodes.There are two hypotheses for the origin of the Laplace resonance among Io, Europa, and Ganymede: that it is primordial and has existed from the beginning of the Solar System; or that it developed after the formation of the Solar System. A possible sequence of events for the latter scenario is as follows: Io raised tides on Jupiter, causing Io's orbit to expand (due to conservation of momentum) until it encountered the 2:1 resonance with Europa; after that the expansion continued, but some of the angular moment was transferred to Europa as the resonance caused its orbit to expand as well; the process continued until Europa encountered the 2:1 resonance with Ganymede. Eventually the drift rates of conjunctions between all three moons were synchronized and locked in the Laplace resonance.
| 1
|
[
"Ganymede (moon)",
"named after",
"Ganymede"
] |
Ganymede, or Jupiter III, is the largest and most massive natural satellite of Jupiter as well as in the Solar System, being a planetary-mass moon. It is the largest Solar System object without an atmosphere, despite being the only moon of the Solar System with a magnetic field. Like Titan it is larger than the planet Mercury, but has somewhat less surface gravity than Mercury, Io or the Moon.Ganymede is composed of approximately equal amounts of silicate rock and water. It is a fully differentiated body with an iron-rich, liquid core, and an internal ocean that may contain more water than all of Earth's oceans combined. Its surface is composed of two main types of terrain. Dark regions, saturated with impact craters and dated to four billion years ago, cover about a third of it. Lighter regions, crosscut by extensive grooves and ridges and only slightly less ancient, cover the remainder. The cause of the light terrain's disrupted geology is not fully known, but was likely the result of tectonic activity due to tidal heating. Ganymede orbits Jupiter in roughly seven days and is in a 1:2:4 orbital resonance with the moons Europa and Io, respectively.
Possessing a metallic core, it has the lowest moment of inertia factor of any solid body in the Solar System. Ganymede's magnetic field is probably created by convection within its liquid iron core, also created by Jupiter's tidal forces. The meager magnetic field is buried within Jupiter's far larger magnetic field and would show only as a local perturbation of the field lines. Ganymede has a thin oxygen atmosphere that includes O, O2, and possibly O3 (ozone). Atomic hydrogen is a minor atmospheric constituent. Whether Ganymede has an ionosphere associated with its atmosphere is unresolved.Ganymede's discovery is credited to Simon Marius and Galileo Galilei, who both observed it in 1610, as the third of the Galilean moons, the first group of objects discovered orbiting another planet. Its name was soon suggested by astronomer Simon Marius, after the mythological Ganymede, a Trojan prince desired by Zeus (the Greek counterpart of Jupiter), who carried him off to be the cupbearer of the gods. Beginning with Pioneer 10, several spacecraft have explored Ganymede. The Voyager probes, Voyager 1 and Voyager 2, refined measurements of its size, while Galileo discovered its underground ocean and magnetic field. The next planned mission to the Jovian system is the European Space Agency's Jupiter Icy Moon Explorer (JUICE), which was launched in 2023. After flybys of all three icy Galilean moons, it is planned to enter orbit around Ganymede.
| 2
|
[
"Ganymede (moon)",
"instance of",
"moon of Jupiter"
] |
Name
Galileo claimed the right to name the moons he had discovered. He considered "Cosmian Stars" and settled on "Medicean Stars", in honor of Cosimo II de' Medici.The French astronomer Nicolas-Claude Fabri de Peiresc suggested individual names from the Medici family for the moons, but his proposal was not taken up. Simon Marius, who had originally claimed to have found the Galilean satellites, tried to name the moons the "Saturn of Jupiter", the "Jupiter of Jupiter" (this was Ganymede), the "Venus of Jupiter", and the "Mercury of Jupiter", another nomenclature that never caught on. From a suggestion by Johannes Kepler, Marius suggested a different naming system based on Greek mythology:
Jupiter is much blamed by the poets on account of his irregular loves. Three maidens are especially mentioned as having been clandestinely courted by Jupiter with success. Io, daughter of the River Inachus, Callisto of Lycaon, Europa of Agenor. Then there was Ganymede, the handsome son of King Tros, whom Jupiter, having taken the form of an eagle, transported to heaven on his back, as poets fabulously tell... I think, therefore, that I shall not have done amiss if the First is called by me Io, the Second Europa, the Third, on account of its majesty of light, Ganymede, the Fourth Callisto...
This name and those of the other Galilean satellites fell into disfavor for a considerable time, and were not in common use until the mid-20th century. In much of the earlier astronomical literature, Ganymede is referred to instead by its Roman numeral designation, Jupiter III (a system introduced by Galileo), in other words "the third satellite of Jupiter". Following the discovery of moons of Saturn, a naming system based on that of Kepler and Marius was used for Jupiter's moons. Ganymede is the only Galilean moon of Jupiter named after a male figure—like Io, Europa, and Callisto, he was a lover of Zeus.
The Galilean satellites retain the Italian spellings of their names. In the cases of Io, Europa and Callisto, these are identical to the Latin, but the Latin form of Ganymede is Ganymedes. In English, the final 'e' is silent, perhaps under the influence of French, unlike later names taken from Latin and Greek.
| 5
|
[
"Ganymede (moon)",
"instance of",
"planetary-mass moon"
] |
Physical characteristics
Size
With a diameter of about 5,270 kilometres (3,270 mi) and a mass of 1.48×1020 tonnes (1.48×1023 kg; 3.26×1023 lb), Ganymede is the largest and most massive moon in the Solar System. It is slightly more massive than the second most massive moon, Saturn's satellite Titan, and is more than twice as massive as the Earth's Moon. It is larger than the planet Mercury, which has a diameter of 4,880 kilometres (3,030 mi), but is only 45 percent of Mercury's mass. Ganymede is the ninth-largest object in the solar system, but the tenth-most massive.
| 7
|
[
"Trapezium Cluster",
"discoverer or inventor",
"Galileo Galilei"
] |
The Trapezium or Orion Trapezium Cluster, also known by its Bayer designation of Theta1 Orionis, is a tight open cluster of stars in the heart of the Orion Nebula, in the constellation of Orion. It was discovered by Galileo Galilei. On 4 February 1617 he sketched three of the stars (A, C and D), but missed the surrounding nebulosity. A fourth component (B) was identified by several observers in 1673, and several more components were discovered later like E, for a total of eight by 1888. Subsequently, several of the stars were determined to be binaries. Telescopes of amateur astronomers from about 5-inch (130 mm) aperture can resolve six stars under good seeing conditions.The Trapezium is a relatively young cluster that has formed directly out of the parent nebula. The five brightest stars are on the order of 15 to 30 solar masses in size. They are within a diameter of 1.5 light-years of each other and are responsible for much of the illumination of the surrounding nebula. The Trapezium may be a sub-component of the larger Orion Nebula Cluster, a grouping of about 2,000 stars within a diameter of 20 light-years.
| 0
|
[
"Trapezium Cluster",
"has part(s)",
"Theta1 Orionis C"
] |
The Trapezium or Orion Trapezium Cluster, also known by its Bayer designation of Theta1 Orionis, is a tight open cluster of stars in the heart of the Orion Nebula, in the constellation of Orion. It was discovered by Galileo Galilei. On 4 February 1617 he sketched three of the stars (A, C and D), but missed the surrounding nebulosity. A fourth component (B) was identified by several observers in 1673, and several more components were discovered later like E, for a total of eight by 1888. Subsequently, several of the stars were determined to be binaries. Telescopes of amateur astronomers from about 5-inch (130 mm) aperture can resolve six stars under good seeing conditions.The Trapezium is a relatively young cluster that has formed directly out of the parent nebula. The five brightest stars are on the order of 15 to 30 solar masses in size. They are within a diameter of 1.5 light-years of each other and are responsible for much of the illumination of the surrounding nebula. The Trapezium may be a sub-component of the larger Orion Nebula Cluster, a grouping of about 2,000 stars within a diameter of 20 light-years.Identification
The Trapezium is most readily identifiable by the asterism of four relatively bright stars for which it is named. The four are often identified as A, B, C and D in order of increasing right ascension. The brightest of the four stars is C, or Theta1 Orionis C, with an apparent magnitude of 5.13. Both A and B have been identified as eclipsing binaries.
Infrared images of the Trapezium are better able to penetrate the surrounding clouds of dust, and have located many more stellar components. About half the stars within the cluster have been found to contain evaporating circumstellar disks, a likely precursor to planetary formation. In addition, brown dwarfs and low-mass runaway stars have been identified.
| 7
|
[
"Trapezium Cluster",
"has part(s)",
"Theta1 Orionis B"
] |
The Trapezium or Orion Trapezium Cluster, also known by its Bayer designation of Theta1 Orionis, is a tight open cluster of stars in the heart of the Orion Nebula, in the constellation of Orion. It was discovered by Galileo Galilei. On 4 February 1617 he sketched three of the stars (A, C and D), but missed the surrounding nebulosity. A fourth component (B) was identified by several observers in 1673, and several more components were discovered later like E, for a total of eight by 1888. Subsequently, several of the stars were determined to be binaries. Telescopes of amateur astronomers from about 5-inch (130 mm) aperture can resolve six stars under good seeing conditions.The Trapezium is a relatively young cluster that has formed directly out of the parent nebula. The five brightest stars are on the order of 15 to 30 solar masses in size. They are within a diameter of 1.5 light-years of each other and are responsible for much of the illumination of the surrounding nebula. The Trapezium may be a sub-component of the larger Orion Nebula Cluster, a grouping of about 2,000 stars within a diameter of 20 light-years.
| 9
|
[
"Trapezium Cluster",
"instance of",
"stellar association"
] |
The Trapezium or Orion Trapezium Cluster, also known by its Bayer designation of Theta1 Orionis, is a tight open cluster of stars in the heart of the Orion Nebula, in the constellation of Orion. It was discovered by Galileo Galilei. On 4 February 1617 he sketched three of the stars (A, C and D), but missed the surrounding nebulosity. A fourth component (B) was identified by several observers in 1673, and several more components were discovered later like E, for a total of eight by 1888. Subsequently, several of the stars were determined to be binaries. Telescopes of amateur astronomers from about 5-inch (130 mm) aperture can resolve six stars under good seeing conditions.The Trapezium is a relatively young cluster that has formed directly out of the parent nebula. The five brightest stars are on the order of 15 to 30 solar masses in size. They are within a diameter of 1.5 light-years of each other and are responsible for much of the illumination of the surrounding nebula. The Trapezium may be a sub-component of the larger Orion Nebula Cluster, a grouping of about 2,000 stars within a diameter of 20 light-years.
| 11
|
[
"Galilean transformation",
"discoverer or inventor",
"Galileo Galilei"
] |
Translation
Although the transformations are named for Galileo, it is the absolute time and space as conceived by Isaac Newton that provides their domain of definition. In essence, the Galilean transformations embody the intuitive notion of addition and subtraction of velocities as vectors.
The notation below describes the relationship under the Galilean transformation between the coordinates (x, y, z, t) and (x′, y′, z′, t′) of a single arbitrary event, as measured in two coordinate systems S and S′, in uniform relative motion (velocity v) in their common x and x′ directions, with their spatial origins coinciding at time t = t′ = 0:
| 0
|
[
"Galilean transformation",
"named after",
"Galileo Galilei"
] |
Translation
Although the transformations are named for Galileo, it is the absolute time and space as conceived by Isaac Newton that provides their domain of definition. In essence, the Galilean transformations embody the intuitive notion of addition and subtraction of velocities as vectors.
The notation below describes the relationship under the Galilean transformation between the coordinates (x, y, z, t) and (x′, y′, z′, t′) of a single arbitrary event, as measured in two coordinate systems S and S′, in uniform relative motion (velocity v) in their common x and x′ directions, with their spatial origins coinciding at time t = t′ = 0:
| 1
|
[
"Galilean transformation",
"has part(s)",
"velocity"
] |
Translation
Although the transformations are named for Galileo, it is the absolute time and space as conceived by Isaac Newton that provides their domain of definition. In essence, the Galilean transformations embody the intuitive notion of addition and subtraction of velocities as vectors.
The notation below describes the relationship under the Galilean transformation between the coordinates (x, y, z, t) and (x′, y′, z′, t′) of a single arbitrary event, as measured in two coordinate systems S and S′, in uniform relative motion (velocity v) in their common x and x′ directions, with their spatial origins coinciding at time t = t′ = 0:
| 2
|
[
"Galilean transformation",
"has part(s)",
"time"
] |
Translation
Although the transformations are named for Galileo, it is the absolute time and space as conceived by Isaac Newton that provides their domain of definition. In essence, the Galilean transformations embody the intuitive notion of addition and subtraction of velocities as vectors.
The notation below describes the relationship under the Galilean transformation between the coordinates (x, y, z, t) and (x′, y′, z′, t′) of a single arbitrary event, as measured in two coordinate systems S and S′, in uniform relative motion (velocity v) in their common x and x′ directions, with their spatial origins coinciding at time t = t′ = 0:
| 4
|
[
"Galilean transformation",
"has part(s)",
"rotation matrix"
] |
G(R′, v′, a′, s′) ⋅ G(R, v, a, s) = G(R′ R, R′ v + v′, R′ a + a′ + v′ s, s′ + s).The set of all Galilean transformations Gal(3) forms a group with composition as the group operation.
The group is sometimes represented as a matrix group with spacetime events (x, t, 1) as vectors where t is real and x ∈ R3 is a position in space.
The action is given by(
R
v
a
0
1
s
0
0
1
)
(
x
t
1
)
=
(
R
x
+
v
t
+
a
t
+
s
1
)
,
{\displaystyle {\begin{pmatrix}R&v&a\\0&1&s\\0&0&1\end{pmatrix}}{\begin{pmatrix}x\\t\\1\end{pmatrix}}={\begin{pmatrix}Rx+vt+a\\t+s\\1\end{pmatrix}},}
where s is real and v, x, a ∈ R3 and R is a rotation matrix.
The composition of transformations is then accomplished through matrix multiplication. Care must be taken in the discussion whether one restricts oneself to the connected component group of the orthogonal transformations.
Gal(3) has named subgroups. The identity component is denoted SGal(3).
Let m represent the transformation matrix with parameters v, R, s, a:
| 10
|
[
"Square–cube law",
"discoverer or inventor",
"Galileo Galilei"
] |
The square–cube law (or cube–square law) is a mathematical principle, applied in a variety of scientific fields, which describes the relationship between the volume and the surface area as a shape's size increases or decreases. It was first described in 1638 by Galileo Galilei in his Two New Sciences as the "...ratio of two volumes is greater than the ratio of their surfaces".This principle states that, as a shape grows in size, its volume grows faster than its surface area. When applied to the real world, this principle has many implications which are important in fields ranging from mechanical engineering to biomechanics. It helps explain phenomena including why large mammals like elephants have a harder time cooling themselves than small ones like mice, and why building taller and taller skyscrapers is increasingly difficult.
| 0
|
[
"Square–cube law",
"instance of",
"scientific law"
] |
The square–cube law (or cube–square law) is a mathematical principle, applied in a variety of scientific fields, which describes the relationship between the volume and the surface area as a shape's size increases or decreases. It was first described in 1638 by Galileo Galilei in his Two New Sciences as the "...ratio of two volumes is greater than the ratio of their surfaces".This principle states that, as a shape grows in size, its volume grows faster than its surface area. When applied to the real world, this principle has many implications which are important in fields ranging from mechanical engineering to biomechanics. It helps explain phenomena including why large mammals like elephants have a harder time cooling themselves than small ones like mice, and why building taller and taller skyscrapers is increasingly difficult.
| 1
|
[
"PackBits",
"discoverer or inventor",
"Apple"
] |
PackBits is a fast, simple lossless compression scheme for run-length encoding of data.
Apple introduced the PackBits format with the release of MacPaint on the Macintosh computer. This compression scheme can be used in TIFF files. TGA files also use this RLE compression scheme, but treats data stream as pixels instead of bytes.
A PackBits data stream consists of packets with a one-byte header followed by data. The header is a signed byte; the data can be signed, unsigned, or packed (such as MacPaint pixels).
In the following table, n is the value of the header byte as a signed integer.
| 0
|
[
"Tholin",
"discoverer or inventor",
"Carl Sagan"
] |
Overview
The term "tholin" was coined by astronomer Carl Sagan and his colleague Bishun Khare to describe the difficult-to-characterize substances they obtained in his Miller–Urey-type experiments on the methane-containing gas mixtures such as those found in Titan's atmosphere. Their paper proposing the name "tholin" said:
| 0
|
[
"Tholin",
"color",
"red"
] |
Moons
Titan
Titan tholins are nitrogen-rich organic substances produced by the irradiation of the gaseous mixtures of nitrogen and methane found in the atmosphere and surface of Titan. Titan's atmosphere is about 97% nitrogen, 2.7±0.1% methane and the remaining trace amounts of other gases. In the case of Titan, the haze and orange-red color of its atmosphere are both thought to be caused by the presence of tholins.Dwarf planets
Pluto
Tholins occur on the dwarf planet Pluto and are responsible for red colors as well as the blue tint of the atmosphere of Pluto. The reddish-brown cap of the north pole of Charon, the largest of five moons of Pluto, is thought to be composed of tholins, produced from methane, nitrogen and related gases released from the atmosphere of Pluto and transferred over about 19,000 km (12,000 mi) distance to the orbiting moon.Kuiper belt objects and Centaurs
The reddish color typical of tholins is characteristic of many Trans-Neptunian objects, including plutinos in the outer Solar System such as 28978 Ixion. Spectral reflectances of Centaurs also suggest the presence of tholins on their surfaces. The New Horizons exploration of the classical Kuiper belt object 486958 Arrokoth revealed reddish color at its surface, suggestive of tholins.
| 1
|
[
"Tholin",
"color",
"brown"
] |
Dwarf planets
Pluto
Tholins occur on the dwarf planet Pluto and are responsible for red colors as well as the blue tint of the atmosphere of Pluto. The reddish-brown cap of the north pole of Charon, the largest of five moons of Pluto, is thought to be composed of tholins, produced from methane, nitrogen and related gases released from the atmosphere of Pluto and transferred over about 19,000 km (12,000 mi) distance to the orbiting moon.
| 3
|
[
"Tholin",
"has part(s)",
"organic compound"
] |
Moons
Titan
Titan tholins are nitrogen-rich organic substances produced by the irradiation of the gaseous mixtures of nitrogen and methane found in the atmosphere and surface of Titan. Titan's atmosphere is about 97% nitrogen, 2.7±0.1% methane and the remaining trace amounts of other gases. In the case of Titan, the haze and orange-red color of its atmosphere are both thought to be caused by the presence of tholins.Europa
Colored regions on Jupiter's satellite Europa are thought to be tholins. The morphology of Europa's impact craters and ridges is suggestive of fluidized material welling up from the fractures where pyrolysis and radiolysis take place. In order to generate colored tholins on Europa there must be a source of materials (carbon, nitrogen, and water), and a source of energy to drive the reactions. Impurities in the water ice crust of Europa are presumed both to emerge from the interior as cryovolcanic events that resurface the body, and to accumulate from space as interplanetary dust.
| 5
|
[
"Tholin",
"discoverer or inventor",
"Bishun Khare"
] |
Overview
The term "tholin" was coined by astronomer Carl Sagan and his colleague Bishun Khare to describe the difficult-to-characterize substances they obtained in his Miller–Urey-type experiments on the methane-containing gas mixtures such as those found in Titan's atmosphere. Their paper proposing the name "tholin" said:
| 8
|
[
"Carbon chauvinism",
"discoverer or inventor",
"Carl Sagan"
] |
Concept
The term was used as early as 1973, when scientist Carl Sagan described it and other human chauvinisms that limit imagination of possible extraterrestrial life. It suggests that human beings, as carbon-based life forms who have never encountered any life that has evolved outside the Earth's environment, may find it difficult to envision radically different biochemistries.
| 0
|
[
"Carbon chauvinism",
"instance of",
"hypothesis"
] |
Carbon chauvinism is a neologism meant to disparage the assumption that the chemical processes of hypothetical extraterrestrial life must be constructed primarily from carbon (organic compounds) because as far as we know, carbon's chemical and thermodynamic properties render it far superior to all other elements at forming molecules used in living organisms.Concept
The term was used as early as 1973, when scientist Carl Sagan described it and other human chauvinisms that limit imagination of possible extraterrestrial life. It suggests that human beings, as carbon-based life forms who have never encountered any life that has evolved outside the Earth's environment, may find it difficult to envision radically different biochemistries.
| 2
|
[
"Carbon chauvinism",
"facet of",
"extraterrestrial life"
] |
Carbon chauvinism is a neologism meant to disparage the assumption that the chemical processes of hypothetical extraterrestrial life must be constructed primarily from carbon (organic compounds) because as far as we know, carbon's chemical and thermodynamic properties render it far superior to all other elements at forming molecules used in living organisms.
| 3
|
[
"Prince de la Moskowa",
"named after",
"Moskva River"
] |
The titles of Duke of Elchingen (French: Duc d'Elchingen) and Prince of the Moskva (Prince de la Moskowa) were created by Napoleon, Emperor of the French, for the Marshal of the Empire Michel Ney. Both were victory titles; Ney was created Duke of Elchingen in 1808, after the Battle of Elchingen, and Prince of the Moskva after the Battle of Borodino near a branch of the Moskva River, 125 km outside Moscow (named Bataille de la Moskova in French, in reference to the river). In 1814, Ney became a peer of France. On his execution in 1815, the peerage was revoked, but it was restored in 1831.
Clauses in the titles' patents of creation caused the title of Prince of the Moskva to pass to Ney's eldest son, Joseph, and the dukedom of Elchingen to pass to his second son, Michel. This ensured that the two titles would never be held by the same person if there was another heir living, a similar situation to the British titles of Duke of Hamilton and Earl of Selkirk.
The two titles were reunited in one person in 1928, and both became extinct with the death of the last heir in 1969.
| 2
|
[
"Prince de la Moskowa",
"instance of",
"noble title"
] |
The titles of Duke of Elchingen (French: Duc d'Elchingen) and Prince of the Moskva (Prince de la Moskowa) were created by Napoleon, Emperor of the French, for the Marshal of the Empire Michel Ney. Both were victory titles; Ney was created Duke of Elchingen in 1808, after the Battle of Elchingen, and Prince of the Moskva after the Battle of Borodino near a branch of the Moskva River, 125 km outside Moscow (named Bataille de la Moskova in French, in reference to the river). In 1814, Ney became a peer of France. On his execution in 1815, the peerage was revoked, but it was restored in 1831.
Clauses in the titles' patents of creation caused the title of Prince of the Moskva to pass to Ney's eldest son, Joseph, and the dukedom of Elchingen to pass to his second son, Michel. This ensured that the two titles would never be held by the same person if there was another heir living, a similar situation to the British titles of Duke of Hamilton and Earl of Selkirk.
The two titles were reunited in one person in 1928, and both became extinct with the death of the last heir in 1969.
| 3
|
[
"Pasteurization",
"discoverer or inventor",
"Louis Pasteur"
] |
Pasteurization or pasteurisation is a process of food preservation in which packaged and non-packaged foods (such as milk and fruit juices) are treated with mild heat, usually to less than 100 °C (212 °F), to eliminate pathogens and extend shelf life.
The process is intended to destroy or deactivate microorganisms and enzymes that contribute to food spoilage or risk of disease, including vegetative bacteria, but most bacterial spores survive the process.The process is named after the French microbiologist Louis Pasteur whose research in the 1860s demonstrated that thermal processing would deactivate unwanted microorganisms in wine. Spoilage enzymes are also inactivated during pasteurization. Today, pasteurization is used widely in the dairy industry and other food processing industries to achieve food preservation and food safety.By the year 1999, most liquid products were heat treated in a continuous system where heat can be applied using a heat exchanger or the direct or indirect use of hot water and steam. Due to the mild heat, there are minor changes to the nutritional quality and sensory characteristics of the treated foods. Pascalization or high pressure processing (HPP) and pulsed electric field (PEF) are non-thermal processes that are also used to pasteurize foods.
| 0
|
[
"Pasteurization",
"named after",
"Louis Pasteur"
] |
Pasteurization or pasteurisation is a process of food preservation in which packaged and non-packaged foods (such as milk and fruit juices) are treated with mild heat, usually to less than 100 °C (212 °F), to eliminate pathogens and extend shelf life.
The process is intended to destroy or deactivate microorganisms and enzymes that contribute to food spoilage or risk of disease, including vegetative bacteria, but most bacterial spores survive the process.The process is named after the French microbiologist Louis Pasteur whose research in the 1860s demonstrated that thermal processing would deactivate unwanted microorganisms in wine. Spoilage enzymes are also inactivated during pasteurization. Today, pasteurization is used widely in the dairy industry and other food processing industries to achieve food preservation and food safety.By the year 1999, most liquid products were heat treated in a continuous system where heat can be applied using a heat exchanger or the direct or indirect use of hot water and steam. Due to the mild heat, there are minor changes to the nutritional quality and sensory characteristics of the treated foods. Pascalization or high pressure processing (HPP) and pulsed electric field (PEF) are non-thermal processes that are also used to pasteurize foods.
| 1
|
[
"Pasteur effect",
"discoverer or inventor",
"Louis Pasteur"
] |
The Pasteur effect describes how available oxygen inhibits ethanol fermentation, driving yeast to switch toward aerobic respiration for increased generation of the energy carrier adenosine triphosphate (ATP).Discovery
The effect was described by Louis Pasteur in 1857 in experiments showing that aeration of yeasted broth causes cell growth to increase while the fermentation rate decreases, based on lowered ethanol production.
| 0
|
[
"Pasteur effect",
"named after",
"Louis Pasteur"
] |
The Pasteur effect describes how available oxygen inhibits ethanol fermentation, driving yeast to switch toward aerobic respiration for increased generation of the energy carrier adenosine triphosphate (ATP).Discovery
The effect was described by Louis Pasteur in 1857 in experiments showing that aeration of yeasted broth causes cell growth to increase while the fermentation rate decreases, based on lowered ethanol production.
| 1
|
[
"Fluorine",
"instance of",
"chemical element"
] |
Noble gases
Noble gases, having complete electron shells, defied reaction with other elements until 1962 when Neil Bartlett reported synthesis of xenon hexafluoroplatinate; xenon difluoride, tetrafluoride, hexafluoride, and multiple oxyfluorides have been isolated since then. Among other noble gases, krypton forms a difluoride, and radon and fluorine generate a solid suspected to be radon difluoride. Binary fluorides of lighter noble gases are exceptionally unstable: argon and hydrogen fluoride combine under extreme conditions to give argon fluorohydride. Helium and neon have no long-lived fluorides, and no neon fluoride has ever been observed; helium fluorohydride has been detected for milliseconds at high pressures and low temperatures.
| 6
|
[
"Fluorine",
"discoverer or inventor",
"Henri Moissan"
] |
Fluorine is a chemical element with the symbol F and atomic number 9. It is the lightest halogen and exists at standard conditions as a highly toxic, pale yellow diatomic gas. As the most electronegative reactive element, it is extremely reactive, as it reacts with all other elements except for the light inert gases.
Among the elements, fluorine ranks 24th in universal abundance and 13th in terrestrial abundance. Fluorite, the primary mineral source of fluorine which gave the element its name, was first described in 1529; as it was added to metal ores to lower their melting points for smelting, the Latin verb fluo meaning 'flow' gave the mineral its name. Proposed as an element in 1810, fluorine proved difficult and dangerous to separate from its compounds, and several early experimenters died or sustained injuries from their attempts. Only in 1886 did French chemist Henri Moissan isolate elemental fluorine using low-temperature electrolysis, a process still employed for modern production. Industrial production of fluorine gas for uranium enrichment, its largest application, began during the Manhattan Project in World War II.
Owing to the expense of refining pure fluorine, most commercial applications use fluorine compounds, with about half of mined fluorite used in steelmaking. The rest of the fluorite is converted into corrosive hydrogen fluoride en route to various organic fluorides, or into cryolite, which plays a key role in aluminium refining. Molecules containing a carbon–fluorine bond often have very high chemical and thermal stability; their major uses are as refrigerants, electrical insulation and cookware, and PTFE (Teflon). Pharmaceuticals such as atorvastatin and fluoxetine contain C−F bonds. The fluoride ion from dissolved fluoride salts inhibits dental cavities, and so finds use in toothpaste and water fluoridation. Global fluorochemical sales amount to more than US$69 billion a year.
Fluorocarbon gases are generally greenhouse gases with global-warming potentials 100 to 23,500 times that of carbon dioxide, and SF6 has the highest global warming potential of any known substance. Organofluorine compounds often persist in the environment due to the strength of the carbon–fluorine bond. Fluorine has no known metabolic role in mammals; a few plants and sea sponges synthesize organofluorine poisons (most often monofluoroacetates) that help deter predation.
| 8
|
[
"Fluorine",
"part of",
"perfluorinated compound"
] |
Polymers
Polymers exhibit the same stability increases afforded by fluorine substitution (for hydrogen) in discrete molecules; their melting points generally increase too. Polytetrafluoroethylene (PTFE), the simplest fluoropolymer and perfluoro analogue of polyethylene with structural unit –CF2–, demonstrates this change as expected, but its very high melting point makes it difficult to mold. Various PTFE derivatives are less temperature-tolerant but easier to mold: fluorinated ethylene propylene replaces some fluorine atoms with trifluoromethyl groups, perfluoroalkoxy alkanes do the same with trifluoromethoxy groups, and Nafion contains perfluoroether side chains capped with sulfonic acid groups. Other fluoropolymers retain some hydrogen atoms; polyvinylidene fluoride has half the fluorine atoms of PTFE and polyvinyl fluoride has a quarter, but both behave much like perfluorinated polymers.
| 12
|
[
"Fluorine",
"has effect",
"fluorine exposure"
] |
Toxicity
Elemental fluorine is highly toxic to living organisms. Its effects in humans start at concentrations lower than hydrogen cyanide's 50 ppm and are similar to those of chlorine: significant irritation of the eyes and respiratory system as well as liver and kidney damage occur above 25 ppm, which is the immediately dangerous to life and health value for fluorine. The eyes and nose are seriously damaged at 100 ppm, and inhalation of 1,000 ppm fluorine will cause death in minutes, compared to 270 ppm for hydrogen cyanide.
| 18
|
[
"Ampère's force law",
"instance of",
"physical law"
] |
In magnetostatics, the force of attraction or repulsion between two current-carrying wires (see first figure below) is often called Ampère's force law. The physical origin of this force is that each wire generates a magnetic field, following the Biot–Savart law, and the other wire experiences a magnetic force as a consequence, following the Lorentz force law.
| 2
|
[
"Methane",
"has part(s)",
"hydrogen"
] |
Methane (US: MEH-thayn, UK: MEE-thayn) is a chemical compound with the chemical formula CH4 (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Earth makes it an economically attractive fuel, although capturing and storing it poses technical challenges due to its gaseous state under normal conditions for temperature and pressure.
Naturally occurring methane is found both below ground and under the seafloor and is formed by both geological and biological processes. The largest reservoir of methane is under the seafloor in the form of methane clathrates. When methane reaches the surface and the atmosphere, it is known as atmospheric methane.The Earth's atmospheric methane concentration has increased by about 260% since 1750—with the overwhelming percentage caused by human activity and accounted for 20% of the total radiative forcing from all of the long-lived and globally mixed greenhouse gases, according to the 2021 Intergovernmental Panel on Climate Change report.Methane has also been detected on other planets, including Mars, which has implications for astrobiology research.
| 0
|
[
"Methane",
"has part(s)",
"carbon"
] |
Fuel
Methane is used as a fuel for ovens, homes, water heaters, kilns, automobiles, turbines, etc. Activated carbon is used to store methane.
As the major constituent of natural gas, methane is important for electricity generation by burning it as a fuel in a gas turbine or steam generator. Compared to other hydrocarbon fuels, methane produces less carbon dioxide for each unit of heat released. At about 891 kJ/mol, methane's heat of combustion is lower than that of any other hydrocarbon, but the ratio of the heat of combustion (891 kJ/mol) to the molecular mass (16.0 g/mol, of which 12.0 g/mol is carbon) shows that methane, being the simplest hydrocarbon, produces more heat per mass unit (55.7 kJ/g) than other complex hydrocarbons. In many cities, methane is piped into homes for domestic heating and cooking. In this context it is usually known as natural gas, which is considered to have an energy content of 39 megajoules per cubic meter, or 1,000 BTU per standard cubic foot. Liquefied natural gas (LNG) is predominantly methane (CH4) converted into liquid form for ease of storage or transport.
Refined liquid methane as well as LNG is used as a rocket fuel, when combined with liquid oxygen, as in the BE-4 and Raptor engines. Due to the similarities between methane and LNG such engines are commonly grouped together under the term methalox.
As a liquid rocket propellant, methane offers the advantage over kerosene of producing small exhaust molecules. This deposits less soot on the internal parts of rocket motors, reducing the difficulty of booster re-use. The lower molecular weight of the exhaust also increases the fraction of the heat energy which is in the form of kinetic energy available for propulsion, increasing the specific impulse of the rocket. Compared to liquid hydrogen, the specific energy of methane is lower but this disadvantage is offset by methane's greater density and temperature range, allowing for smaller and lighter tankage for a given fuel mass. Liquid methane has a temperature range (91–112 K) nearly compatible with liquid oxygen (54–90 K).
| 1
|
[
"Methane",
"has effect",
"air pollution"
] |
Public safety and the environment
Methane "degrades air quality and adversely impacts human health, agricultural yields, and ecosystem productivity".Methane is extremely flammable and may form explosive mixtures with air. Methane gas explosions are responsible for many deadly mining disasters. A methane gas explosion was the cause of the Upper Big Branch coal mine disaster in West Virginia on April 5, 2010, killing 29. Natural gas accidental release has also been a major focus in the field of safety engineering, due to past accidental releases that concluded in the formation of jet fire disasters.The 2015-2016 methane gas leak in Aliso Canyon, California was considered to be the worst in terms of its environmental effect in American history. It was also described as more damaging to the environment than Deepwater Horizon's leak in the Gulf of Mexico.In May 2023 The Guardian published a report, blaming Turkmenistan to be the worst in the world for methane super emitting. The data collected by Kayrros researchers indicate, that two large Turkmen fossil fuel fields leaked 2.6m and 1.8m tonnes of methane in 2022 alone, pumping the CO2 equivalent of 366m tonnes into the atmosphere, surpassing the annual CO2 emissions of the United Kingdom.Methane is also an asphyxiant if the oxygen concentration is reduced to below about 16% by displacement, as most people can tolerate a reduction from 21% to 16% without ill effects. The concentration of methane at which asphyxiation risk becomes significant is much higher than the 5–15% concentration in a flammable or explosive mixture. Methane off-gas can penetrate the interiors of buildings near landfills and expose occupants to significant levels of methane. Some buildings have specially engineered recovery systems below their basements to actively capture this gas and vent it away from the building.
| 2
|
[
"Methane",
"instance of",
"alkane"
] |
Etymology
Etymologically, the word methane is coined from the chemical suffix "-ane", which denotes substances belonging to the alkane family; and the word methyl, which is derived from the German methyl (1840) or directly from the French méthyle, which is a back-formation from the French méthylène (corresponding to English "methylene"), the root of which was coined by Jean-Baptiste Dumas and Eugène Péligot in 1834 from the Greek μέθυ methy (wine) (related to English "mead") and ὕλη hyle (meaning "wood"). The radical is named after this because it was first detected in methanol, an alcohol first isolated by distillation of wood. The chemical suffix -ane is from the coordinating chemical suffix -ine which is from Latin feminine suffix -ina which is applied to represent abstracts. The coordination of "-ane", "-ene", "-one", etc. was proposed in 1866 by German chemist August Wilhelm von Hofmann.
| 5
|
[
"Methane",
"discoverer or inventor",
"Alessandro Volt"
] |
Occurrence
Methane was discovered and isolated by Alessandro Volta between 1776 and 1778 when studying marsh gas from Lake Maggiore. It is the major component of natural gas, about 87% by volume. The major source of methane is extraction from geological deposits known as natural gas fields, with coal seam gas extraction becoming a major source (see coal bed methane extraction, a method for extracting methane from a coal deposit, while enhanced coal bed methane recovery is a method of recovering methane from non-mineable coal seams). It is associated with other hydrocarbon fuels, and sometimes accompanied by helium and nitrogen. Methane is produced at shallow levels (low pressure) by anaerobic decay of organic matter and reworked methane from deep under the Earth's surface. In general, the sediments that generate natural gas are buried deeper and at higher temperatures than those that contain oil.
Methane is generally transported in bulk by pipeline in its natural gas form, or by LNG carriers in its liquefied form; few countries transport it by truck.History
In November 1776, methane was first scientifically identified by Italian physicist Alessandro Volta in the marshes of Lake Maggiore straddling Italy and Switzerland. Volta was inspired to search for the substance after reading a paper written by Benjamin Franklin about "flammable air". Volta collected the gas rising from the marsh, and by 1778 had isolated pure methane. He also demonstrated that the gas could be ignited with an electric spark.Following the Felling mine disaster of 1812 in which 92 men perished, Sir Humphry Davy established that the feared firedamp was in fact largely methane.The name "methane" was coined in 1866 by the German chemist August Wilhelm von Hofmann. The name was derived from methanol.
| 16
|
[
"Methane",
"has quality",
"odorlessness"
] |
Properties and bonding
Methane is a tetrahedral molecule with four equivalent C–H bonds. Its electronic structure is described by four bonding molecular orbitals (MOs) resulting from the overlap of the valence orbitals on C and H. The lowest-energy MO is the result of the overlap of the 2s orbital on carbon with the in-phase combination of the 1s orbitals on the four hydrogen atoms. Above this energy level is a triply degenerate set of MOs that involve overlap of the 2p orbitals on carbon with various linear combinations of the 1s orbitals on hydrogen. The resulting "three-over-one" bonding scheme is consistent with photoelectron spectroscopic measurements.
Methane is an odorless gas and appears to be colorless. It does absorb visible light especially at the red end of the spectrum due to overtone bands, but the effect is only noticeable if the light path is very long. This is what gives Uranus and Neptune their blue or bluish-green colors, as light passes through their atmospheres containing methane and is then scattered back out.The familiar smell of natural gas as used in homes is achieved by the addition of an odorant, usually blends containing tert-butylthiol, as a safety measure. Methane has a boiling point of −161.5 °C at a pressure of one atmosphere. As a gas, it is flammable over a range of concentrations (5.4–17%) in air at standard pressure.
Solid methane exists in several modifications. Presently nine are known. Cooling methane at normal pressure results in the formation of methane I. This substance crystallizes in the cubic system (space group Fm3m). The positions of the hydrogen atoms are not fixed in methane I, i.e. methane molecules may rotate freely. Therefore, it is a plastic crystal.
| 37
|
[
"Methane",
"part of",
"methanogenesis"
] |
Biological routes
Most of Earth's methane is biogenic and is produced by methanogenesis, a form of anaerobic respiration only known to be conducted by some members of the domain Archaea. Methanogens occupy landfills and other soils, ruminants (for example, cattle), the guts of termites, and the anoxic sediments below the seafloor and the bottom of lakes. Rice fields also generate large amounts of methane during plant growth. This multistep process is used by these microorganisms for energy. The net reaction of methanogenesis is:
| 42
|
[
"Methane",
"part of",
"methane metabolic process"
] |
Biological routes
Most of Earth's methane is biogenic and is produced by methanogenesis, a form of anaerobic respiration only known to be conducted by some members of the domain Archaea. Methanogens occupy landfills and other soils, ruminants (for example, cattle), the guts of termites, and the anoxic sediments below the seafloor and the bottom of lakes. Rice fields also generate large amounts of methane during plant growth. This multistep process is used by these microorganisms for energy. The net reaction of methanogenesis is:
| 46
|
[
"Methane",
"instance of",
"group 14 hydride"
] |
Methane (US: MEH-thayn, UK: MEE-thayn) is a chemical compound with the chemical formula CH4 (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Earth makes it an economically attractive fuel, although capturing and storing it poses technical challenges due to its gaseous state under normal conditions for temperature and pressure.
Naturally occurring methane is found both below ground and under the seafloor and is formed by both geological and biological processes. The largest reservoir of methane is under the seafloor in the form of methane clathrates. When methane reaches the surface and the atmosphere, it is known as atmospheric methane.The Earth's atmospheric methane concentration has increased by about 260% since 1750—with the overwhelming percentage caused by human activity and accounted for 20% of the total radiative forcing from all of the long-lived and globally mixed greenhouse gases, according to the 2021 Intergovernmental Panel on Climate Change report.Methane has also been detected on other planets, including Mars, which has implications for astrobiology research.
| 57
|
[
"Methane",
"subclass of",
"biogenic aliphatic hydrocarbon"
] |
Biological routes
Most of Earth's methane is biogenic and is produced by methanogenesis, a form of anaerobic respiration only known to be conducted by some members of the domain Archaea. Methanogens occupy landfills and other soils, ruminants (for example, cattle), the guts of termites, and the anoxic sediments below the seafloor and the bottom of lakes. Rice fields also generate large amounts of methane during plant growth. This multistep process is used by these microorganisms for energy. The net reaction of methanogenesis is:CO2 + 4 H2 → CH4 + 2 H2O
The final step in the process is catalyzed by the enzyme methyl coenzyme M reductase (MCR).
| 58
|
[
"Methane",
"instance of",
"type of chemical entity"
] |
Methane (US: MEH-thayn, UK: MEE-thayn) is a chemical compound with the chemical formula CH4 (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Earth makes it an economically attractive fuel, although capturing and storing it poses technical challenges due to its gaseous state under normal conditions for temperature and pressure.
Naturally occurring methane is found both below ground and under the seafloor and is formed by both geological and biological processes. The largest reservoir of methane is under the seafloor in the form of methane clathrates. When methane reaches the surface and the atmosphere, it is known as atmospheric methane.The Earth's atmospheric methane concentration has increased by about 260% since 1750—with the overwhelming percentage caused by human activity and accounted for 20% of the total radiative forcing from all of the long-lived and globally mixed greenhouse gases, according to the 2021 Intergovernmental Panel on Climate Change report.Methane has also been detected on other planets, including Mars, which has implications for astrobiology research.
| 61
|
[
"Methane",
"has quality",
"colorlessness"
] |
Properties and bonding
Methane is a tetrahedral molecule with four equivalent C–H bonds. Its electronic structure is described by four bonding molecular orbitals (MOs) resulting from the overlap of the valence orbitals on C and H. The lowest-energy MO is the result of the overlap of the 2s orbital on carbon with the in-phase combination of the 1s orbitals on the four hydrogen atoms. Above this energy level is a triply degenerate set of MOs that involve overlap of the 2p orbitals on carbon with various linear combinations of the 1s orbitals on hydrogen. The resulting "three-over-one" bonding scheme is consistent with photoelectron spectroscopic measurements.
Methane is an odorless gas and appears to be colorless. It does absorb visible light especially at the red end of the spectrum due to overtone bands, but the effect is only noticeable if the light path is very long. This is what gives Uranus and Neptune their blue or bluish-green colors, as light passes through their atmospheres containing methane and is then scattered back out.The familiar smell of natural gas as used in homes is achieved by the addition of an odorant, usually blends containing tert-butylthiol, as a safety measure. Methane has a boiling point of −161.5 °C at a pressure of one atmosphere. As a gas, it is flammable over a range of concentrations (5.4–17%) in air at standard pressure.
Solid methane exists in several modifications. Presently nine are known. Cooling methane at normal pressure results in the formation of methane I. This substance crystallizes in the cubic system (space group Fm3m). The positions of the hydrogen atoms are not fixed in methane I, i.e. methane molecules may rotate freely. Therefore, it is a plastic crystal.
| 63
|
[
"Mingghan",
"discoverer or inventor",
"Genghis Khan"
] |
Mingghan was a social-military unit of 1,000 households created by Genghis Khan. From this group could be recruited a Mongol regiment of 1,000 men. It is part of the ancient method of organization developed by the nomads of Central Asia based on the decimal system. Tumen, which included 10,000 households and soldiers, was the largest group and it was divided into ten mingghan. A mingghan was made up of 10 jaghuns or 100 arbans. An account cited that once he becomes a guard, it is the duty of a mingghan commander's son to bring a younger brother and 10 other men to serve with him.
| 0
|
[
"Mingghan",
"subclass of",
"military unit"
] |
Mingghan was a social-military unit of 1,000 households created by Genghis Khan. From this group could be recruited a Mongol regiment of 1,000 men. It is part of the ancient method of organization developed by the nomads of Central Asia based on the decimal system. Tumen, which included 10,000 households and soldiers, was the largest group and it was divided into ten mingghan. A mingghan was made up of 10 jaghuns or 100 arbans. An account cited that once he becomes a guard, it is the duty of a mingghan commander's son to bring a younger brother and 10 other men to serve with him.
| 1
|
[
"Mingghan",
"has part(s)",
"soldier"
] |
Mingghan was a social-military unit of 1,000 households created by Genghis Khan. From this group could be recruited a Mongol regiment of 1,000 men. It is part of the ancient method of organization developed by the nomads of Central Asia based on the decimal system. Tumen, which included 10,000 households and soldiers, was the largest group and it was divided into ten mingghan. A mingghan was made up of 10 jaghuns or 100 arbans. An account cited that once he becomes a guard, it is the duty of a mingghan commander's son to bring a younger brother and 10 other men to serve with him.
| 2
|
[
"Leonardo's robot",
"discoverer or inventor",
"Leonardo da Vinci"
] |
Leonardo's robot, or Leonardo's mechanical knight (Italian: Automa cavaliere, lit. "Automaton knight"), was a humanoid automaton designed and possibly constructed by Leonardo da Vinci around the year 1495.The design notes for the robot appear in sketchbooks that were rediscovered in the 1950s. Leonardo is said to have displayed the machine at a celebration hosted by Ludovico Sforza at the court of Milan in 1495. The robot knight could stand, sit, raise its visor and independently manoeuvre its arms, and had an anatomically correct jaw. The entire robotic system was operated by a series of pulleys and cables. Since the discovery of the sketchbook, the robot has been built faithfully based on Leonardo's design and was found to be fully functional.The robot is described as being clad in German-Italian medieval armor, and is able to make several human-like motions. It is partially a result of Leonardo's anatomical research in the Canon of Proportions as described in the Vitruvian Man.
| 0
|
[
"Leonardo's robot",
"creator",
"Leonardo da Vinci"
] |
Leonardo's robot, or Leonardo's mechanical knight (Italian: Automa cavaliere, lit. "Automaton knight"), was a humanoid automaton designed and possibly constructed by Leonardo da Vinci around the year 1495.The design notes for the robot appear in sketchbooks that were rediscovered in the 1950s. Leonardo is said to have displayed the machine at a celebration hosted by Ludovico Sforza at the court of Milan in 1495. The robot knight could stand, sit, raise its visor and independently manoeuvre its arms, and had an anatomically correct jaw. The entire robotic system was operated by a series of pulleys and cables. Since the discovery of the sketchbook, the robot has been built faithfully based on Leonardo's design and was found to be fully functional.The robot is described as being clad in German-Italian medieval armor, and is able to make several human-like motions. It is partially a result of Leonardo's anatomical research in the Canon of Proportions as described in the Vitruvian Man.
| 1
|
[
"Leonardo's robot",
"instance of",
"humanoid robot"
] |
Leonardo's robot, or Leonardo's mechanical knight (Italian: Automa cavaliere, lit. "Automaton knight"), was a humanoid automaton designed and possibly constructed by Leonardo da Vinci around the year 1495.The design notes for the robot appear in sketchbooks that were rediscovered in the 1950s. Leonardo is said to have displayed the machine at a celebration hosted by Ludovico Sforza at the court of Milan in 1495. The robot knight could stand, sit, raise its visor and independently manoeuvre its arms, and had an anatomically correct jaw. The entire robotic system was operated by a series of pulleys and cables. Since the discovery of the sketchbook, the robot has been built faithfully based on Leonardo's design and was found to be fully functional.The robot is described as being clad in German-Italian medieval armor, and is able to make several human-like motions. It is partially a result of Leonardo's anatomical research in the Canon of Proportions as described in the Vitruvian Man.
| 2
|
[
"Leonardo's robot",
"instance of",
"invention"
] |
Leonardo's robot, or Leonardo's mechanical knight (Italian: Automa cavaliere, lit. "Automaton knight"), was a humanoid automaton designed and possibly constructed by Leonardo da Vinci around the year 1495.The design notes for the robot appear in sketchbooks that were rediscovered in the 1950s. Leonardo is said to have displayed the machine at a celebration hosted by Ludovico Sforza at the court of Milan in 1495. The robot knight could stand, sit, raise its visor and independently manoeuvre its arms, and had an anatomically correct jaw. The entire robotic system was operated by a series of pulleys and cables. Since the discovery of the sketchbook, the robot has been built faithfully based on Leonardo's design and was found to be fully functional.The robot is described as being clad in German-Italian medieval armor, and is able to make several human-like motions. It is partially a result of Leonardo's anatomical research in the Canon of Proportions as described in the Vitruvian Man.
| 3
|
[
"Sfumato",
"discoverer or inventor",
"Leonardo da Vinci"
] |
Sfumato (Italian: [sfuˈmaːto], English: ) is a painting technique for softening the transition between colours, mimicking an area beyond what the human eye is focusing on, or the out-of-focus plane. It is one of the canonical painting modes of the Renaissance. Leonardo da Vinci was the most prominent practitioner of sfumato, based on his research in optics and human vision, and his experimentation with the camera obscura. He introduced it and implemented it in many of his works, including the Virgin of the Rocks and in his famous painting of the Mona Lisa. He described sfumato as "without lines or borders, in the manner of smoke".According to the theory of the art historian Marcia B. Hall, which has gained considerable acceptance, sfumato is one of four modes of painting colours available to Italian High Renaissance painters, along with cangiante, chiaroscuro, and unione.
| 1
|
[
"Sfumato",
"instance of",
"painting technique"
] |
Sfumato (Italian: [sfuˈmaːto], English: ) is a painting technique for softening the transition between colours, mimicking an area beyond what the human eye is focusing on, or the out-of-focus plane. It is one of the canonical painting modes of the Renaissance. Leonardo da Vinci was the most prominent practitioner of sfumato, based on his research in optics and human vision, and his experimentation with the camera obscura. He introduced it and implemented it in many of his works, including the Virgin of the Rocks and in his famous painting of the Mona Lisa. He described sfumato as "without lines or borders, in the manner of smoke".According to the theory of the art historian Marcia B. Hall, which has gained considerable acceptance, sfumato is one of four modes of painting colours available to Italian High Renaissance painters, along with cangiante, chiaroscuro, and unione.
| 2
|
[
"Leonardo's crossbow",
"instance of",
"invention"
] |
Design
The crossbow as a weapon had been around long before Leonardo's designs. However, his designs made the weapon more advanced and why Leonardo's crossbows stands out. If a crossbow is designed with a narrower shaft and a tapered bolt, which adjusts the nocking of arrows, it greatly improves the airflow of the bow and the drag on arrows. This allows the crossbow to operate much more efficiently and have a more precise aim. These ideas were present in Leonardo's designs and were developed independently of any other influences.The mathematics that Leonardo utilized to construct his crossbow designs were far advanced despite having some now known inaccuracies with today's current knowledge of geometrics and design. Nonetheless, Leonardo was "the first modern engineer to attempt to apply the geometrical mathematics of the laws of motion to the design of machines." The other mathematical marvel that is noted in Leonardo's designs of the crossbows is the proportional techniques that he utilized in every aspect of the designs.Mechanically, the Rapid Fire Crossbow's tiller was split into two stacked wooden pieces held together at the front by a hinge and held in place at the back by a spring-loaded latch. Sandwiched inside the tiller, a pair of interconnected folding levers attach the lower half of the tiller to a sliding plank sitting on the top half of the tiller between the two metal prods, similar in mechanical concept to the Gastraphetes, that contained the rolling nut and spring-loaded sear at the back of the plank. Meanwhile, the bottom half of the tiller contained the trigger. Upon pressing a switch on the side of the tiller to release the latch, the user can then fold the bottom half of the tiller down. At the same time, the interconnected levers then push the sliding plank forward until the drawstring is caught by the rolling nut, which is held secure by the sear's spring tension. Upon pushing the bottom half of the tiller back into place, the latch locks the upper and lower halves of the tiller back together. After a bolt is loaded on the crossbow and aimed, the trigger is then pulled to compress the sear's spring and enable the rolling nut to release the drawstring to propel the bolt. Such a design removed the need for external spanning tools that an arbalist had to carry and simplified the arming process of the crossbow.
With regards to the Giant Crossbow, the original idea of Leonardo, as described in the drawings of the Codex Atlanticus (1488–1489), was to build a large crossbow in order to increase the range and power of its ammunition. The Giant Crossbow was used to fire rocks and bombs; it was mostly intended to be an intimidation-based weapon for deterring foes from attacking. The Giant Crossbow was made up of thin wood, on 6 wheels, 27 yards across, and made up of 39 separate parts. While some believe that Leonardo designed the Giant Crossbow for his own amusement, the context around this design suggests the Giant Crossbow truly was intended to be a dangerous weapon that would greatly appeal to his employer, Ludovico Sforza. Inspiration for such a weapon most likely stemmed from the fact that Leonardo grew up in Italy during the 15th century. This meant he was a witness to the constant warfare between the many city-states in his area. Thus, Leonardo put extensive time and effort into designs that could both protect his fellow citizens and greatly harm the enemy. The Giant Crossbow supports this theory in that the intended enormous size of the weapon was meant to invoke fear and panic in its enemies to keep them away, but it would still have the capability to cause great damage and injury had it been actually constructed and used.
| 3
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[
"Leonardo's fighting vehicle",
"discoverer or inventor",
"Leonardo da Vinci"
] |
Leonardo da Vinci's fighting vehicle is one of the conceptions of the revered Italian polymath and artist Leonardo da Vinci.Design
The concept was designed while Leonardo da Vinci was under the patronage of Ludovico Sforza in 1487. Sometimes described as a prototype of modern tanks, Leonardo's armored vehicle represented a conical cover inspired by a turtle's shell. The covering was to be made of wood and reinforced with metal plates that add to the thickness. Slanting angles would deflect enemy fire. The machine was powered by two large cranks operated internally by four strong men. The vehicle was equipped with an array of light cannons, placed around the perimeter.The gears of the design were located in a reversed order, making the vehicle unworkable. This is thought by some sources to have been a deliberate mistake by Leonardo as a form of security, in case his design was stolen and used irresponsibly. It is almost impossible to fix this problem successfully without taking away power from its forward movement and strength. Regardless, the vehicle would have been too heavy to move and would have lacked the battlefield mobility seen in modern tanks that make them so effective.The armored vehicle was designed to intimidate the enemy rather than to be used as a serious military weapon. Due to the vehicle's impressive size, it would not be capable of moving on rugged terrain. The project could hardly be applied and realized in the 15th century.Around 2010, a group of engineers recreated Leonardo's vehicle, based on the original design, and fixed the mistake in gearing.
| 0
|
[
"Leonardo's fighting vehicle",
"creator",
"Leonardo da Vinci"
] |
Leonardo da Vinci's fighting vehicle is one of the conceptions of the revered Italian polymath and artist Leonardo da Vinci.Design
The concept was designed while Leonardo da Vinci was under the patronage of Ludovico Sforza in 1487. Sometimes described as a prototype of modern tanks, Leonardo's armored vehicle represented a conical cover inspired by a turtle's shell. The covering was to be made of wood and reinforced with metal plates that add to the thickness. Slanting angles would deflect enemy fire. The machine was powered by two large cranks operated internally by four strong men. The vehicle was equipped with an array of light cannons, placed around the perimeter.The gears of the design were located in a reversed order, making the vehicle unworkable. This is thought by some sources to have been a deliberate mistake by Leonardo as a form of security, in case his design was stolen and used irresponsibly. It is almost impossible to fix this problem successfully without taking away power from its forward movement and strength. Regardless, the vehicle would have been too heavy to move and would have lacked the battlefield mobility seen in modern tanks that make them so effective.The armored vehicle was designed to intimidate the enemy rather than to be used as a serious military weapon. Due to the vehicle's impressive size, it would not be capable of moving on rugged terrain. The project could hardly be applied and realized in the 15th century.Around 2010, a group of engineers recreated Leonardo's vehicle, based on the original design, and fixed the mistake in gearing.
| 1
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