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These Solar System minor planets are the furthest from the Sun as of December 2021 [update] . The objects have been categorized by their approximate current distance from the Sun, and not by the calculated aphelion of their orbit. The list changes over time because the objects are moving in their orbits. Some objects are inbound and some are outbound. It would be difficult to detect long-distance comets if it were not for their comas , which become visible when heated by the Sun. Distances are measured in astronomical units (AU, Sun–Earth distances). The distances are not the minimum ( perihelion ) or the maximum ( aphelion ) that may be achieved by these objects in the future.
This list does not include near-parabolic comets of which many are known to be currently more than 100 AU (15 billion km ) from the Sun, but are currently too far away to be observed by telescope. Trans-Neptunian objects are typically announced publicly months or years after their discovery, so as to make sure the orbit is correct before announcing it. Due to their greater distance from the Sun and slow movement across the sky, trans-Neptunian objects with observation arcs less than several years often have poorly constrained orbits. Particularly distant objects take several years of observations to establish a crude orbit solution before being announced. For instance, the most distant known trans-Neptunian object 2018 AG 37 was discovered by Scott Sheppard in January 2018 but was announced three years later in February 2021. [ 1 ]
One particularly distant body is 90377 Sedna , which was discovered in November 2003. It has an extremely eccentric orbit that takes it to an aphelion of 937 AU. [ 2 ] It takes over 10,000 years to orbit, and during the next 50 years it will slowly move closer to the Sun as it comes to perihelion at a distance of 76 AU from the Sun. [ 3 ] Sedna is the largest known sednoid , a class of objects that play an important role in the Planet Nine hypothesis .
Pluto (30–49 AU, about 34 AU in 2015) was the first Kuiper belt object to be discovered (1930) and is the largest known dwarf planet .
This is a list of known objects at heliocentric distances of more than 65 AU. In theory, the Oort cloud could extend over 120,000 AU (2 ly ) from the Sun.
Solar System → Local Interstellar Cloud → Local Bubble → Gould Belt → Orion Arm → Milky Way → Milky Way subgroup → Local Group → Local Sheet → Virgo Supercluster → Laniakea Supercluster → Local Hole → Observable universe → Universe Each arrow ( → ) may be read as "within" or "part of". | https://en.wikipedia.org/wiki/List_of_Solar_System_objects_most_distant_from_the_Sun |
This is a list of space probes that have left Earth orbit (or were launched with that intention but failed), organized by their planned destination. It includes planetary probes, solar probes, and probes to asteroids and comets. Flybys (such as gravity assists ) that were incidental to the main purpose of the mission are also included.
Excluded are lunar missions, which are listed separately at List of lunar probes and List of Apollo missions . Flybys of Earth are listed separately at List of Earth flybys . Planned and proposed missions are in the List of proposed Solar System probes .
Colour key:
While the Sun is not physically explorable with current technology, the following solar observation probes have been designed and launched to operate in heliocentric orbit or at one of the Earth–Sun Lagrangian points – additional solar observatories were placed in Earth orbit and are not included in this list:
[ 4 ]
Early programs encompassing multiple spacecraft include:
In addition, several planetary probes have sent back observations of the Earth-Moon system shortly after launch, most notably Mariner 10 , Pioneers 10 and 11 and both Voyager probes ( Voyager 1 and Voyager 2 ).
Major early programs encompassing multiple probes include:
For completeness, this section lists probes that have left (or will leave) Earth orbit, but are not primarily targeted at any of the above bodies.
Solar System → Local Interstellar Cloud → Local Bubble → Gould Belt → Orion Arm → Milky Way → Milky Way subgroup → Local Group → Local Sheet → Virgo Supercluster → Laniakea Supercluster → Local Hole → Observable universe → Universe Each arrow ( → ) may be read as "within" or "part of". | https://en.wikipedia.org/wiki/List_of_Solar_System_probes |
This is a list of calculators created and produced in Soviet Union .
Source: [ 1 ]
"B" in "B3" stands for "bytovaya" (Russian: бытовая), which means "domestic".
C in "C3" stands for Svetlana (company) (Russian: Светлана).
"MK" stands for "microcalculator" (Russian: микрокалькулятор). | https://en.wikipedia.org/wiki/List_of_Soviet_calculators |
This is the list of Soviet computer systems . The Russian abbreviation EVM (ЭВМ), present in some of the names below, means "electronic computing machine" (Russian: электронная вычислительная машина ).
The Russian abbreviation EVM (ЭВМ), present in some of the names below, means "electronic computing machine" (Russian: электронная вычислительная машина ).
Computer systems from the Ministry of Radio Technology : [ 1 ]
Computer systems from the Ministry of Instrument Making : [ 1 ]
Computer systems from the Ministry of Electronics Industry : [ 1 ] | https://en.wikipedia.org/wiki/List_of_Soviet_computer_systems |
This list of Standard Networks products includes all major standalone services and programs created by Standard Networks, a Madison, Wisconsin-based software company founded in 1989 [ 1 ] and acquired by Ipswitch, Inc. in 2008. [ 2 ] All products listed are well into their gold releases. This list also includes previous products that are no longer being actively developed. | https://en.wikipedia.org/wiki/List_of_Standard_Networks_products |
Sun Microsystems , from its inception in 1982 to its acquisition by Oracle Corporation in 2010, became known for being "something of a farm system for Silicon Valley." [ 1 ] It had a number of employees credited with notable achievements before, during or after their tenure there. | https://en.wikipedia.org/wiki/List_of_Sun_Microsystems_employees |
This article compares SysML tools. SysML tools are software applications which support some functions of the Systems Modeling Language . | https://en.wikipedia.org/wiki/List_of_SysML_tools |
This is a list of TCP and UDP port numbers used by protocols for operation of network applications. The Transmission Control Protocol (TCP) and the User Datagram Protocol (UDP) only need one port for bidirectional traffic. TCP usually uses port numbers that match the services of the corresponding UDP implementations, if they exist, and vice versa.
The Internet Assigned Numbers Authority (IANA) is responsible for maintaining the official assignments of port numbers for specific uses, [ 1 ] However, many unofficial uses of both well-known and registered port numbers occur in practice. Similarly, many of the official assignments refer to protocols that were never or are no longer in common use. This article lists port numbers and their associated protocols that have experienced significant uptake.
The port numbers in the range from 0 to 1023 (0 to 2 10 − 1) are the well-known ports or system ports . [ 3 ] They are used by system processes that provide widely used types of network services. On Unix-like operating systems, a process must execute with superuser privileges to be able to bind a network socket to an IP address using one of the well-known ports. [ 5 ]
The range of port numbers from 1024 to 49151 (2 10 to 2 15 + 2 14 − 1) are the registered ports . They are assigned by IANA for specific service upon application by a requesting entity. [ 2 ] On most systems, registered ports can be used without superuser privileges.
The range 49152–65535 (2 15 + 2 14 to 2 16 − 1), 16 384 ports, contains dynamic or private ports that cannot be registered with IANA. [ 486 ] This range is used for private or customized services, for temporary purposes, and for automatic allocation of ephemeral ports .
[ 212 ]
To run our code, type the following command in the terminal:
sails lift
Your app will be running on localhost:1337 . Let's test it. ... | https://en.wikipedia.org/wiki/List_of_TCP_and_UDP_port_numbers |
X , commonly called under the former name Twitter , is an American microblogging and social networking service on which users post and interact with messages known as "tweets". Registered users can post, like and retweet tweets, and read those that are publicly available.
Tweets, a term for short posts, are publicly visible by default, but senders can restrict message delivery to only their followers. Users can mute users they do not wish to interact with, block accounts from viewing their tweets and remove accounts from their followers list. [ 1 ] [ 2 ] [ 3 ] Users can tweet via the Twitter website, compatible external applications (such as for smartphones ), or by Short Message Service (SMS) available in certain countries. [ 4 ] Users may subscribe to other users' tweets—this is known as "following" and subscribers are known as "followers" [ 5 ] or "tweeps", a portmanteau of Twitter and peeps. [ 6 ] Individual tweets can be forwarded by other users to their own feed, a process known as a "retweet", a term for reposting. In 2015, Twitter launched "quote tweet" (originally called "retweet with comment"), [ 7 ] a feature that allows users to add a comment to their retweet, nesting one tweet in the other. [ 8 ] Users can also " like " (formerly "favorite") individual tweets. [ 9 ]
The counters for "likes", "retweets", and replies appear next to the respective buttons in news feeds , called timelines , [ 10 ] such as on profile pages and search results. Counters for likes and retweets exist on a tweet's standalone page too. Since September 2020, quote tweets, formerly known as "retweet with comment", have an own counter on their tweet page. [ 7 ] Until the legacy desktop front end that was discontinued in 2020, a row with miniature profile pictures of up to ten liking or retweeting users was displayed (earliest documented implementation in December 2011 overhaul), as well as a tweet reply counter next to the according button on a tweet's page. [ 11 ] [ 12 ]
Twitter allows users to update their profile via their mobile phone either by text messaging or by apps released for certain smartphones and tablets. [ 13 ] Twitter has been compared to a web-based Internet Relay Chat (IRC) client. [ 14 ] In a 2009 Time magazine essay, technology author Steven Johnson described the basic mechanics of Twitter as "remarkably simple":
As a social network, Twitter revolves around the principle of followers. When you choose to follow another Twitter user, that user's tweets appear in reverse chronological order on your main Twitter page. If you follow 20 people, you'll see a mix of tweets scrolling down the page: breakfast-cereal updates, interesting new links, music recommendations, even musings on the future of education. [ 15 ]
According to research published in April 2014, around 44% of user accounts have never tweeted. [ 16 ]
The first tweet was posted by Jack Dorsey (creator) at 12:50 pm PST on March 21, 2006, and read "just setting up my twttr". [ 17 ] In 2009, the first tweet was sent from space. US astronauts Nicola Stott and Jeff Williams took part in a live 'tweetup' from the International Space Station with around 35 members of the public at the NASA Headquarters in Washington, D.C. [ 18 ]
In March 2021, Jack Dorsey listed his first tweet for sale. The highest bid for the tweet, $2.5 million, came from a Malaysian businessman, Sina Estavi. Along with the metadata of the original tweet, the buyer was to receive a certificate that was digitally signed and verified by Dorsey. [ 19 ]
San Antonio -based market-research firm Pear Analytics analyzed 2,000 tweets (originating from the United States and in English) over a two-week period in August 2009 from 11:00 am to 5:00 pm (CST) and separated them into six categories. [ 20 ] Pointless babble made up 40%, with 38% being conversational. Pass-along value had 9%, self-promotion 6% with spam and news each making 4%.
Despite Jack Dorsey's own open contention that a message on Twitter is "a short burst of inconsequential information", social networking researcher Danah Boyd responded to the Pear Analytics survey by arguing that what the Pear researchers labeled "pointless babble" is better characterized as " social grooming " or "peripheral awareness" (which she justifies as persons "want[ing] to know what the people around them are thinking and doing and feeling, even when co-presence isn't viable"). [ 21 ] Similarly, a survey of Twitter users found that a more specific social role of passing along messages that include a hyperlink is an expectation of reciprocal linking by followers. [ 22 ]
Users can group posts together by topic or type by use of hashtags – words or phrases prefixed with a " # " sign. Similarly, the " @ " sign followed by a username is used for mentioning or replying to other users. [ 23 ]
In 2014, in anticipation for the FIFA World Cup , Twitter introduced hashflags, special hashtags that automatically generate a custom emoji next to them for a certain period of time, following the success of a similar campaign during the 2010 World Cup . [ 24 ] Hashflags may be generated by Twitter themselves (such as to raise awareness for social issues ) [ 25 ] or be purchased by corporations (such as to promote products and events). [ 26 ]
To repost a message from another Twitter user and share it with one's own followers, a user can click the retweet button within the Tweet. Users can reply other accounts' replies. Since November 2019, users can hide replies to their messages. Since May 2020, users can select who can reply each of their tweets before sending them: anyone, accounts who follow the poster, specific accounts, and none. This ability was upgraded in July 2021 to make the feature retroactively applicable to tweets after they have been sent out. [ 27 ] [ 28 ]
In late 2009, the "Twitter Lists" feature was added, making it possible for users to follow ad hoc lists of authors instead of individual authors. [ 5 ] [ 29 ]
Through SMS, users can communicate with Twitter through five gateway numbers: short codes for the United States, Canada, India, New Zealand, and an Isle of Man -based number for international use. There is also a short code in the United Kingdom which is only accessible to those on the Vodafone , O2 [ 30 ] and Orange [ 31 ] networks. In India, since Twitter only supports tweets from Bharti Airtel , [ 32 ] an alternative platform called smsTweet [ 33 ] was set up by a user to work on all networks. [ 34 ] A similar platform called GladlyCast exists for mobile phone users in Singapore and Malaysia. [ 35 ]
The tweets were set to a largely constrictive 140-character limit for compatibility with SMS messaging, introducing the shorthand notation and slang commonly used in SMS messages. The 140-character limit also increased the usage of URL shortening services such as bit.ly , goo.gl , tinyurl.com , tr.im , and other content-hosting services such as TwitPic , memozu.com and NotePub to accommodate multimedia content and text longer than 140 characters. Since June 2011, Twitter has used its own t.co domain for automatic shortening of all URLs posted on its site, making other link shorteners unnecessary for staying within Twitter's 140 character limit. [ 36 ] [ 37 ]
In August 2019, Jack Dorsey's account was hacked by using Twitter's SMS to tweet feature to send crude messages. Days later, the ability to send a tweet via SMS was temporarily turned off. [ 38 ]
In April 2020, Twitter discontinued the ability to receive SMS messages containing the text of new tweets in most countries. [ 39 ] [ 40 ]
In 2016, Twitter announced that media such as photos, videos, and the person's handle, would not count against the already constrictive 140 character limit. A user photo post used to count for a large chunk of a Tweet, about 24 characters. [ 41 ] Attachments and links would also no longer be part of the character limit. [ 42 ]
On March 29, 2016, Twitter introduced the ability to add a caption of up to 480 characters to each image attached to a tweet. [ 43 ] [ 44 ] This caption can be accessed by screen reading software or by hovering the mouse above a picture inside TweetDeck .
Since March 30, 2017, the Twitter handles are outside the tweet itself, therefore they no longer count towards the character limit. [ 45 ] Only new Twitter handles added to the conversation count towards the limit.
In 2017, Twitter doubled their historical 140-character-limitation to 280. [ 46 ] Under the new limit, glyphs are counted as a variable number of characters, depending upon the script they are from: most European letters and punctuation forms count as one character, while each CJK glyph counts as two so that only 140 such glyphs can be used in a tweet. [ 46 ]
t.co is a URL shortening service created by Twitter. [ 36 ] It is only available for links posted to Twitter and not available for general use. [ 36 ] All links posted to Twitter use a t.co wrapper. [ 47 ] Twitter created the service to try to protect users from malicious sites by warning users if a URL is potentially malicious before redirecting them, [ 36 ] and uses the shortener to track clicks on links within tweets. [ 36 ] [ 48 ]
Having used the services of third parties TinyURL and bit.ly , [ 49 ] Twitter began experimenting with its own URL shortening service for private messages in March 2010 using the twt.tl domain, [ 47 ] before it purchased the t.co domain. The service was tested on the main site using the accounts @TwitterAPI, @rsarver and @raffi. [ 47 ] On September 2, 2010, an email from Twitter to users said they would be expanding the roll-out of the service to users. On June 7, 2011, Twitter announced that it was rolling out the feature. [ 37 ]
t.co faced controversy under the ownership of Musk, as Twitter began blocking new Tweets from containing links to other social networks, such as Facebook , Instagram , and Mastodon . [ 50 ] Tweets containing the networks could not be shared, and existing Tweets with links to the restricted sites would give an error upon attempting to visit the page via Twitter. The policy was soon reversed after extreme controversy. [ 51 ]
A word, phrase, or topic that is mentioned at a greater rate than others is said to be a "trending topic". Trending topics become popular either through a concerted effort by users or because of an event that prompts people to talk about a specific topic. [ 52 ] These topics help Twitter and their users to understand what is happening in the world and what people's opinions are about it. [ 53 ] Websites that track and display trending topics, like TwitterTrend.co , provide real-time information on the most discussed topics worldwide, offering users insights into regional and global trends. [ 54 ]
Trending topics are sometimes the result of concerted efforts and manipulations by fans of certain celebrities or cultural phenomena, particularly musicians like Lady Gaga (known as Little Monsters), Justin Bieber (Beliebers), Rihanna (Rih Navy) and One Direction (Directioners), and novel series Twilight (Twihards) and Harry Potter (Potterheads). Twitter has altered the trend algorithm in the past to prevent manipulation of this type with limited success. [ 55 ]
The Twitter web interface displays a list of trending topics on a sidebar on the home page, along with sponsored content (see image).
Twitter often censors trending hashtags that are claimed to be abusive or offensive. Twitter censored the #Thatsafrican [ 56 ] and #thingsdarkiessay hashtags after users complained that they found the hashtags offensive. [ 57 ] There are allegations that Twitter removed # NaMOinHyd from the trending list and added an Indian National Congress -sponsored hashtag. [ 58 ] President Donald Trump protested trends calling them "unfair, disgusting, illegal, ridiculous" claiming the ones that are bad about him are blown up. [ 59 ] [ 60 ] [ 61 ]
Examples of high-impact topics include the wildfires in San Diego, [ 62 ] the earthquake in Japan , [ 63 ] popular sporting events, [ 64 ] and political uprisings in Iran [ 65 ] and Egypt . [ 66 ]
In 2019, 20% of the global trends were found to be fake, created automatically using fake and compromised accounts originating from Turkey. It is reported that 108,000 accounts were employed since 2015 to push 19,000 keywords such as advertisements and political campaigns, to top trends in Turkey by bulk tweeting. [ 67 ]
In October 2015, Twitter introduced "Moments"—a feature that allows users to curate tweets from other users into a larger collection. Twitter initially intended the feature to be used by its in-house editorial team and other partners; they populated a dedicated tab in Twitter's apps, chronicling news headlines, sporting events, and other content. [ 68 ] [ 69 ] In September 2016, creation of moments became available to all Twitter users. [ 70 ] On December 7, 2022, Twitter announced that it would be removing the ability to create new moments to focus on other experiences. [ 71 ]
There are numerous tools for adding content, monitoring content and conversations including Twitter's own TweetDeck , Salesforce.com , HootSuite , and Twitterfeed.com. As of 2009 [update] , fewer than half of tweets posted were posted using the web user interface with most users using third-party applications (based on an analysis of 500 million tweets by Sysomos). [ 72 ]
In June 2009, after being criticized by Kanye West and sued by Tony La Russa over unauthorized accounts run by impersonators , the company launched their "Verified Accounts" program. [ 73 ] [ 74 ] Twitter stated that an account with a "blue tick" verification badge indicates "we've been in contact with the person or entity the account is representing and verified that it is approved". [ 75 ] In July 2016, Twitter announced a public application process to grant verified status to an account "if it is determined to be of public interest" and that verification "does not imply an endorsement". [ 76 ] [ 77 ] [ 78 ] Verified status allows access to some features unavailable to other users, such as only seeing mentions from other verified accounts. [ 79 ]
In November 2020, Twitter announced a relaunch of its verification system in 2021. According to the new policy, Twitter verifies six different types of accounts; for three of them (companies, brands, and influential individuals like activists), the existence of a Wikipedia page will be one criterion for showing that the account has "Off Twitter Notability". [ 80 ] Twitter states that it will re-open public verification applications at some point in "early 2021". [ 81 ]
Twitter has mobile apps for iPhone , iPad , Android , Windows 10 , Windows Phone , BlackBerry , and Nokia S40 . [ 82 ] Users can also tweet by sending SMS. [ 83 ] In April 2017, Twitter introduced Twitter Lite , a progressive web app designed for regions with unreliable and slow Internet connections, with a size of less than one megabyte , designed for devices with limited storage capacity. [ 84 ] [ 85 ]
This has been released in countries with slow internet connection such as the Philippines. [ 86 ]
Twitter Lite has evolved into the main Twitter web interface, see section " interface " . [ citation needed ]
For many years, Twitter has limited the use of third-party applications accessing the service by implementing a 100,000 user limit per application. [ 87 ] Since August 2010, third-party Twitter applications have been required to use OAuth , an authentication method that does not require users to enter their password into the authenticating application. This was done to increase security and improve the user experience. [ 88 ] As of 2023, third-party applications are prohibited under the Twitter API terms of service, with prohibit the use of the API to "create or attempt to create a substitute or similar service or product to the Twitter Applications". [ 89 ] [ 90 ]
This feature adds websites to the bottom of a tweet's permalink page. If a website embedded a tweet onto one of their stories, the tweet will show the websites that mentioned the tweet. This feature was added onto Twitter so if the viewer does not understand what the tweet means, they can click on the sites to read more about what the person is talking about. [ 91 ]
In 2015, Twitter began to roll out the ability to attach poll questions to tweets. Polls are open for up to 7 days, and voters are not personally identified. [ 92 ]
Initially, polls could have only two options with a maximum of twenty characters per option. Later [ when? ] , the ability to add four options with up to 25 characters per option, was added.
On June 1, 2011, Twitter announced its own integrated photo-sharing service that enables users to upload a photo and attach it to a Tweet right from Twitter.com. [ 93 ] Users now also have the ability to add pictures to Twitter's search by adding hashtags to the tweet. [ 94 ] Twitter also plans to provide photo galleries designed to gather and syndicate all photos that a user has uploaded on Twitter and third-party services such as TwitPic. [ 94 ]
In 2016, Twitter began to place a larger focus on live streaming video programming, hosting various events including streams of the Republican and Democratic conventions during the U.S. presidential campaign as part of a partnership with CBS News , [ 95 ] Dreamhack and ESL esports events, [ 96 ] and winning a bid for non-exclusive streaming rights to ten NFL Thursday Night Football games in the 2016 season . [ 96 ] [ 97 ]
During an event in New York in May 2017, Twitter announced that it planned to construct a 24-hour streaming video channel hosted within the service, featuring content from various partners. [ 96 ] [ 98 ] CEO Jack Dorsey stated that the digital video strategy was part of a goal for Twitter to be "the first place that anyone hears of anything going on that matters to them"; as of the first quarter of 2017, Twitter had over 200 content partners, who streamed over 800 hours of video over 450 events. [ 99 ]
Twitter announced a number of new and expanded partnerships for its streaming video services at the event, including Bloomberg , BuzzFeed , Cheddar ( Opening Bell and Closing Bell shows; the latter was introduced in October 2016) IMG Fashion (coverage of fashion events), Live Nation Entertainment (streaming concert events), Major League Baseball (weekly online game stream, plus a weekly program with live look-ins and coverage of trending stories), MTV and BET (red carpet coverage for their MTV Video Music Awards , MTV Movie & TV Awards , and BET Awards ), NFL Network (the Monday-Thursday news program NFL Blitz Live , and Sunday Fantasy Gameday ), [ 100 ] [ 101 ] the PGA Tour ( PGA Tour Live coverage of early tournament rounds preceding television coverage), [ 102 ] The Players' Tribune , Ben Silverman and Howard T. Owens ' Propagate (daily entertainment show #WhatsHappening ), The Verge (weekly technology show Circuit Breaker: The Verge's Gadget Show ), Stadium (a new digital sports network being formed by Silver Chalice and Sinclair Broadcast Group ) [ 103 ] [ 104 ] [ 105 ] and the WNBA (weekly game). [ 99 ]
Twitter has offered two different methods [ clarify ] of archiving one's own Twitter account data. Those methods have their individual benefits and disadvantages. As of September 2019, only the latter archival method is available. [ citation needed ]
In December 2012, Twitter introduced a "Tweet archival" feature, which created a ZIP file that contains an offline-browsable archive of all tweets. [ 106 ] Those exported tweets could be browsed and searched offline by using the bundled user-interface accessible through a web browser , which used client-side, JavaScript-powered pagination . [ 107 ] The user interface of the tweet archive browser had a design similar to Twitter's 2010–2014 desktop user interface, even until the feature's removal. The tweet text contents, ID's, time data and source labels are located in the file called " tweets.csv ". It was possible to request at least one archive per day [ verification needed ] . The ability to export this type of tweet archive, which never existed on the new layout , has been removed entirely in August 2019 [when exactly?] , after co-existing with the new 2018 data archival method. Even when accessing the legacy Twitter desktop website layout using the user-agent of an older browser version, the option has disappeared from the account settings.
Twitter Spaces is a social audio feature that enables users to host or participate in a live-audio virtual environment called space for conversation. Spaces can accommodate an unlimited number of listeners. A maximum of 13 people (1 host, 2 co-hosts and 10 speakers) are allowed onstage. The feature was initially limited to users with at least 600 followers. Since October 21, 2021, any Twitter user can create a Space from the Android or iOS app. [ 108 ]
In March 2020, Twitter began to test a stories feature known as "fleets" in some markets, [ 109 ] [ 110 ] which officially launched on November 17, 2020. [ 111 ] [ 112 ] Similarly to equivalent features, fleets can contain text and media, are only accessible for 24 hours after they are posted, and are accessed within the Twitter app via an area above the timeline. [ 109 ]
In June 2021, Twitter announced it would start implementing advertising into fleets, integrating full-screen ads among user-created content. [ 113 ] On July 14, 2021, Twitter stated that it would remove Fleets by August 3. Twitter had intended for fleets to encourage more users to tweet regularly, rather than simply consume other folks' tweets, but instead fleets were generally used by users who already tweeted a lot. The company stated that their spot at the top of the screen would now be occupied by currently active Spaces from the user's feed. [ 114 ]
On June 3, 2021, Twitter announced a service known as Twitter Blue, which provides features exclusive to those who are subscribers to the Twitter Blue service. They include:
The service was initially released in Australia and Canada. [ 115 ] On November 9, 2021, Twitter Blue was launched for US customers. [ 116 ]
Twitter Zero is an initiative undertaken by Twitter in collaboration with mobile phone -based Internet providers , whereby the providers waive data (bandwidth) charges—so-called " zero-rate "—for accessing Twitter on phones when using a stripped-down text-only version of the website. The images could be loaded by using the Twitter app. [ 117 ] The stripped-down version is available only through providers who have entered the agreement with Twitter. Partners include:
In May 2021, Twitter began testing a Tip Jar feature on its iOS and Android clients. The feature allows users to send monetary tips to certain accounts, providing a financial incentive for content creators on the platform. The Tip Jar is optional and users can choose whether or not to enable tips for their account. The day the feature was launched, a user discovered that sending a tip through PayPal would reveal the sender's address to the recipient. [ 118 ]
On September 23, 2021, Twitter announced that it will allow users to tip users on the social network with bitcoin . The feature will be available for iOS users. Previously, users could tip with fiat currency using services such as Square's Cash app and PayPal's Venmo . Twitter will integrate the Strike bitcoin lightning wallet service. It was noted that at this current time, Twitter will not take a cut of any money sent through the tips feature. [ 119 ]
In July 2021, Twitter launched a test of The Shop Module, a shopping extension that directs customers to a brand's products from its official Twitter account. The feature initially launched for US-based users only and only on iOS. [ 120 ]
On September 1, 2021, Twitter began to roll out Safety Mode, allowing users to reduce disruptive interactions. The rollout began with a small beta-feedback group on iOS, Android, and Twitter's web application . [ 121 ]
The functionality allows users to temporarily block accounts for seven days when potentially harmful language is detected. If a user has Safety Mode enabled, authors of tweets that are identified by Twitter's technology as being harmful or exercising uninvited behavior will be temporarily unable to follow the account, send direct messages, or see tweets from the user with the enabled functionality during the temporary block period. Jarrod Doherty, senior product manager at Twitter, stated that the technology in place within Safety mode assesses existing relationships to prevent blocking accounts that the user frequently interacts with.
Twitter first revealed Safety Mode in February 2021 within the Analyst Day slide deck. [ 122 ]
On September 23, 2021, Twitter revealed that it was experimenting with a feature that would allow users to authenticate and showcase their collections of NFT digital assets on the platform. [ 123 ] The feature was added on January 20, 2022, allowing Twitter Blue subscribers to connect their cryptocurrency wallet to display an NFT they own as a hexagon -shaped profile picture. [ 124 ]
The ability to set new NFT profile pictures was silently removed in January 2024. [ 125 ]
On November 22, 2021, Twitter announced live shopping [ 126 ] feature on its platform. Walmart will be the first retailer to test Twitter's new livestream shopping platform. [ 127 ] The company stated that it is part of their continuing efforts to bring engaging experiences to customers that allow them to shop seamlessly while also being entertained.
Twitter allow companies to showcase up to 50 products for sale on their profiles, as part of new feature testing. Shops will help Twitter to gain a piece of the $45 billion US market for social commerce . [ 128 ]
Community Notes , formerly known as Birdwatch, is a feature on X (formerly Twitter) where contributors can add context such as fact-checks under a post, image or video. It is a community-driven content moderation program, intended to provide helpful and informative context, based on a crowd-sourced system. Notes are applied to potentially misleading content by a bridging-based algorithm not based on majority rule , but instead agreement from users on different sides of the political spectrum .
In January 2025, X partnered with Visa to be the first partner for a new feature called the X Money Account. The product would enable X users to move funds between traditional bank accounts and their digital wallet and make instant peer-to-peer payments. [ 129 ] | https://en.wikipedia.org/wiki/List_of_Twitter_features |
The United States had an offensive biological weapons program from 1943 until 1969. Today, the nation is a member of the Biological Weapons Convention and has renounced biological warfare . | https://en.wikipedia.org/wiki/List_of_U.S._biological_weapons_topics |
The United States chemical weapons program began in 1917 during World War I with the creation of the U.S. Army's Gas Service Section and ended 73 years later in 1990 with the country's practical adoption of the Chemical Weapons Convention (signed 1993; entered into force, 1997). Destruction of stockpiled chemical weapons began in 1985 and is still ongoing. The U.S. Army Medical Research Institute of Chemical Defense , at Aberdeen Proving Ground , Maryland , continues to operate for purely defensive research and education purposes.
The U.S. chemical weapons programs have generally been run by the U.S. Army :
Active bases
Closed bases
The U.S. is party to several treaties which limit chemical weapons:
While these weapon systems were developed, they were not produced or stored in the US chemical weapons stockpile.
Agents stockpiled at the time of Chemical Weapons Convention: | https://en.wikipedia.org/wiki/List_of_U.S._chemical_weapons_topics |
This is a list of UNIVAC products . It ends in 1986, the year that Sperry Corporation merged with Burroughs Corporation to form Unisys as a result of a hostile takeover bid [ 1 ] launched by Burrough's CEO W. Michael Blumenthal. [ 2 ] [ circular reference ]
These machines implemented a variant of the IBM System/360 architecture
This is too small a list. | https://en.wikipedia.org/wiki/List_of_UNIVAC_products |
UN numbers from UN 0001 to UN 0100 as assigned by the United Nations Committee of Experts on the Transport of Dangerous Goods are as follows: | https://en.wikipedia.org/wiki/List_of_UN_numbers_0001_to_0100 |
UN numbers from UN0101 to UN0200 as assigned by the United Nations Committee of Experts on the Transport of Dangerous Goods are as follows: | https://en.wikipedia.org/wiki/List_of_UN_numbers_0101_to_0200 |
UN numbers from UN0201 to UN0300 as assigned by the United Nations Committee of Experts on the Transport of Dangerous Goods are as follows: | https://en.wikipedia.org/wiki/List_of_UN_numbers_0201_to_0300 |
UN numbers from UN0301 to UN0400 as assigned by the United Nations Committee of Experts on the Transport of Dangerous Goods are as follows: | https://en.wikipedia.org/wiki/List_of_UN_numbers_0301_to_0400 |
UN numbers from UN0401 to UN0500 as assigned by the United Nations Committee of Experts on the Transport of Dangerous Goods are as follows: | https://en.wikipedia.org/wiki/List_of_UN_numbers_0401_to_0500 |
UN numbers from UN0501 to UN0600 as assigned by the United Nations Committee of Experts on the Transport of Dangerous Goods are as follows: | https://en.wikipedia.org/wiki/List_of_UN_numbers_0501_to_0600 |
UN numbers from UN1001 to UN1100 as assigned by the United Nations Committee of Experts on the Transport of Dangerous Goods are as follows:
n.o.s. = not otherwise specified meaning a collective entry to which substances, mixtures, solutions or articles may be assigned if a) they are not mentioned by name in 3.2 Dangerous Goods List AND b) they exhibit chemical, physical and/or dangerous properties corresponding to the Class, classification code, packing group and the name and description of the n.o.s. entry [ 2 ] | https://en.wikipedia.org/wiki/List_of_UN_numbers_1001_to_1100 |
UN numbers from UN1101 to UN1200 as assigned by the United Nations Committee of Experts on the Transport of Dangerous Goods are as follows:
n.o.s. = not otherwise specified meaning a collective entry to which substances, mixtures, solutions or articles may be assigned if a) they are not mentioned by name in 3.2 Dangerous Goods List AND b) they exhibit chemical, physical and/or dangerous properties corresponding to the Class, classification code, packing group and the name and description of the n.o.s. entry [ 2 ] | https://en.wikipedia.org/wiki/List_of_UN_numbers_1101_to_1200 |
UN numbers from UN1201 to UN1300 as assigned by the United Nations Committee of Experts on the Transport of Dangerous Goods are as follows:
n.o.s. = not otherwise specified meaning a collective entry to which substances, mixtures, solutions or articles may be assigned if a) they are not mentioned by name in 3.2 Dangerous Goods List AND b) they exhibit chemical, physical and/or dangerous properties corresponding to the Class, classification code, packing group and the name and description of the n.o.s. entry [ 4 ] | https://en.wikipedia.org/wiki/List_of_UN_numbers_1201_to_1300 |
UN numbers from UN1301 to UN1400 as assigned by the United Nations Committee of Experts on the Transport of Dangerous Goods are as follows:
n.o.s. = not otherwise specified meaning a collective entry to which substances, mixtures, solutions or articles may be assigned if a) they are not mentioned by name in 3.2 Dangerous Goods List AND b) they exhibit chemical, physical and/or dangerous properties corresponding to the Class, classification code, packing group and the name and description of the n.o.s. entry [ 2 ] | https://en.wikipedia.org/wiki/List_of_UN_numbers_1301_to_1400 |
UN numbers from UN1401 to UN1500 as assigned by the United Nations Committee of Experts on the Transport of Dangerous Goods are as follows:
n.o.s. = not otherwise specified meaning a collective entry to which substances, mixtures, solutions or articles may be assigned if a) they are not mentioned by name in 3.2 Dangerous Goods List AND b) they exhibit chemical, physical and/or dangerous properties corresponding to the Class, classification code, packing group and the name and description of the n.o.s. entry [ 2 ] | https://en.wikipedia.org/wiki/List_of_UN_numbers_1401_to_1500 |
UN numbers from UN1501 to UN1600 as assigned by the United Nations Committee of Experts on the Transport of Dangerous Goods are as follows:
n.o.s. = not otherwise specified meaning a collective entry to which substances, mixtures, solutions or articles may be assigned if a) they are not mentioned by name in 3.2 Dangerous Goods List AND b) they exhibit chemical, physical and/or dangerous properties corresponding to the Class, classification code, packing group and the name and description of the n.o.s. entry [ 2 ] | https://en.wikipedia.org/wiki/List_of_UN_numbers_1501_to_1600 |
UN numbers from UN1601 to UN1700 as assigned by the United Nations Committee of Experts on the Transport of Dangerous Goods are as follows:
n.o.s. = not otherwise specified meaning a collective entry to which substances, mixtures, solutions or articles may be assigned if a) they are not mentioned by name in 3.2 Dangerous Goods List AND b) they exhibit chemical, physical and/or dangerous properties corresponding to the Class, classification code, packing group and the name and description of the n.o.s. entry [ 2 ] | https://en.wikipedia.org/wiki/List_of_UN_numbers_1601_to_1700 |
UN numbers from UN1701 to UN1800 as assigned by the United Nations Committee of Experts on the Transport of Dangerous Goods are as follows:
n.o.s. = not otherwise specified meaning a collective entry to which substances, mixtures, solutions or articles may be assigned if a) they are not mentioned by name in 3.2 Dangerous Goods List AND b) they exhibit chemical, physical and/or dangerous properties corresponding to the Class, classification code, packing group and the name and description of the n.o.s. entry [ 2 ] | https://en.wikipedia.org/wiki/List_of_UN_numbers_1701_to_1800 |
UN numbers from UN1801 to UN1900 as assigned by the United Nations Committee of Experts on the Transport of Dangerous Goods are as follows:
n.o.s. = not otherwise specified meaning a collective entry to which substances, mixtures, solutions or articles may be assigned if a) they are not mentioned by name in 3.2 Dangerous Goods List AND b) they exhibit chemical, physical and/or dangerous properties corresponding to the Class, classification code, packing group and the name and description of the n.o.s. entry [ 2 ] | https://en.wikipedia.org/wiki/List_of_UN_numbers_1801_to_1900 |
UN numbers from UN1901 to UN2000 as assigned by the United Nations Committee of Experts on the Transport of Dangerous Goods are as follows:
n.o.s. = not otherwise specified meaning a collective entry to which substances, mixtures, solutions or articles may be assigned if a) they are not mentioned by name in 3.2 Dangerous Goods List AND b) they exhibit chemical, physical and/or dangerous properties corresponding to the Class, classification code, packing group and the name and description of the n.o.s.entry [ 3 ] | https://en.wikipedia.org/wiki/List_of_UN_numbers_1901_to_2000 |
UN numbers from UN2001 to UN2100 as assigned by the United Nations Committee of Experts on the Transport of Dangerous Goods are as follows: | https://en.wikipedia.org/wiki/List_of_UN_numbers_2001_to_2100 |
UN numbers from UN2101 to UN2200 as assigned by the United Nations Committee of Experts on the Transport of Dangerous Goods are as follows: | https://en.wikipedia.org/wiki/List_of_UN_numbers_2101_to_2200 |
UN numbers from UN2201 to UN2300 as assigned by the United Nations Committee of Experts on the Transport of Dangerous Goods are as follows: | https://en.wikipedia.org/wiki/List_of_UN_numbers_2201_to_2300 |
UN numbers from UN2301 to UN2400 as assigned by the United Nations Committee of Experts on the Transport of Dangerous Goods are as follows: | https://en.wikipedia.org/wiki/List_of_UN_numbers_2301_to_2400 |
UN numbers from UN2401 to UN2500 as assigned by the United Nations Committee of Experts on the Transport of Dangerous Goods are as follows: | https://en.wikipedia.org/wiki/List_of_UN_numbers_2401_to_2500 |
UN numbers from UN2501 to UN2600 as assigned by the United Nations Committee of Experts on the Transport of Dangerous Goods are as follows: | https://en.wikipedia.org/wiki/List_of_UN_numbers_2501_to_2600 |
UN numbers from UN2601 to UN2700 as assigned by the United Nations Committee of Experts on the Transport of Dangerous Goods are as follows: | https://en.wikipedia.org/wiki/List_of_UN_numbers_2601_to_2700 |
UN numbers from UN2701 to UN2800 as assigned by the United Nations Committee of Experts on the Transport of Dangerous Goods are as follows: | https://en.wikipedia.org/wiki/List_of_UN_numbers_2701_to_2800 |
UN numbers from UN2801 to UN2900 as assigned by the United Nations Committee of Experts on the Transport of Dangerous Goods are as follows: | https://en.wikipedia.org/wiki/List_of_UN_numbers_2801_to_2900 |
UN numbers from UN2901 to UN3000 as assigned by the United Nations Committee of Experts on the Transport of Dangerous Goods are as follows: | https://en.wikipedia.org/wiki/List_of_UN_numbers_2901_to_3000 |
UN numbers from UN3001 to UN3100 as assigned by the United Nations Committee of Experts on the Transport of Dangerous Goods are as follows: | https://en.wikipedia.org/wiki/List_of_UN_numbers_3001_to_3100 |
UN numbers from UN3101 to UN3200 as assigned by the United Nations Committee of Experts on the Transport of Dangerous Goods are as follows: | https://en.wikipedia.org/wiki/List_of_UN_numbers_3101_to_3200 |
UN numbers from UN3201 to UN3300 as assigned by the United Nations Sub-Committee of Experts on the Transport of Dangerous Goods are as follows: | https://en.wikipedia.org/wiki/List_of_UN_numbers_3201_to_3300 |
UN numbers from UN3301 to UN3400 as assigned by the United Nations Committee of Experts on the Transport of Dangerous Goods are as follows: | https://en.wikipedia.org/wiki/List_of_UN_numbers_3301_to_3400 |
UN numbers from UN3401 to UN3500 as assigned by the United Nations Committee of Experts on the Transport of Dangerous Goods are as follows:
b. with not less than 5% but not more than 10% acid by mass | https://en.wikipedia.org/wiki/List_of_UN_numbers_3401_to_3500 |
UN numbers from UN3501 to UN3600 as assigned by the United Nations Committee of Experts on the Transport of Dangerous Goods are as follows:
Medical waste, category A, affecting animals only, solid | https://en.wikipedia.org/wiki/List_of_UN_numbers_3501_to_3600 |
This is a list of UPnP AV media servers and client application or hard appliances.
List of NAS manufacturers – there are many uncatalogued NAS devices with UPnP.
A UPnP client, also called a control point, functions as a digital audio/video remote control. Control points automatically detect UPnP servers on the network to browse content directories and request the transfer or streaming of media. A UPnP media renderer performs the actual audio or video rendering. Control points and media renderers most commonly run on separate devices, the control point being for example a tablet, and the renderer a television or a networked audio computer connected to an audio receiver. Some control points integrate a media renderer and may function as a complete music playing application.
All devices running the BlackBerry 10 operating system include native UPnP media server capabilities. | https://en.wikipedia.org/wiki/List_of_UPnP_AV_media_servers_and_clients |
This article compares UML tools . UML tools are software applications which support some functions of the Unified Modeling Language .
ERD for MySQL, PostgresSQL
. | https://en.wikipedia.org/wiki/List_of_Unified_Modeling_Language_tools |
This is a list of applications supporting the Unified Payments Interface ( UPI ), an Indian instant payment system as well as protocol developed by the National Payments Corporation of India (NPCI) in 2016. The interface facilitates inter-bank peer-to-peer (P2P) and person-to-merchant (P2M) transactions. [ 1 ]
Credit Card Payment
ICICI
HDFC | https://en.wikipedia.org/wiki/List_of_Unified_Payments_Interface_applications |
Usenet is a worldwide, distributed discussion system that uses the Network News Transfer Protocol (NNTP). Programs called newsreaders are used to read and post messages (called articles or posts , and collectively termed news ) to one or more newsgroups . Users must have access to a news server to use a newsreader. This is a list of such newsreaders.
See Web-based Usenet for details. | https://en.wikipedia.org/wiki/List_of_Usenet_newsreaders |
The following is a list of products released for the Vocaloid software in order of release date.
March 5, 2010 (Japan)
Media related to Vocaloid characters, mascots, and others at Wikimedia Commons | https://en.wikipedia.org/wiki/List_of_Vocaloid_products |
This is an incomplete list of gasoline engines designed by Maybach AG, manufactured by Maybach and other firms under licence, and fitted in various German tanks ( German : Panzerkampfwagen , French : chars blindés ) and half-tracks before and during World War II. Until the mid 1930s, German military vehicle manufacturers could source their power plants from a variety of engine makers; by October 1935 the design and manufacture of almost all tank and half-track engines was concentrated in one company, Maybach AG, located in Friedrichshafen on Lake Constance , S. Germany. [ 1 ]
Friedrichshafen was also home to the Zahnradfabrik (ZF) factory which made gearboxes for Panzer III , IV , and Panther tanks . Both Maybach and ZF (and Dornier ) were originally subsidiaries of Luftschiffbau Zeppelin GmbH, which also had a factory in the town.
The firm designed and made a wide range of 4, 6, and 12-cylinder engines from 2.5 to 23 litres; these powered the basic chassis designs for approximately ten tank types (including tank hunters and assault guns), six half-track artillery tractor designs, plus two series of derived armoured personnel carriers . Maybach also designed a number of gearboxes fitted to these vehicles, made under licence by other manufacturers. [ b ]
Maybach used various combinations of factory letter codes (discussed below) which specified the particular ancillaries to be supplied with each engine variant: the same basic model could be fitted in a number of vehicles, according to the original manufacturer's design requirements. For example, the basic 3.8 and 4.2 litre straight-6 engines (the NL38 and HL42) fitted in various half-tracks could be supplied in at least 9 different configurations, although every component was to be found in a single unified parts list. [ 3 ]
However, as the war progressed, a number of problems hampered the German armaments production effort. The factory's inability to manufacture enough complete engines as well as a huge range of spare parts, meant that there was often a lack of both. Conflicts between the civilian Reich Ministry of Armaments and Munitions and the German Army led to a failure to set up an adequate distribution system, and consequent severe shortages of serviceable combat vehicles. In April 1944 an Allied bombing raid put the Maybach factory out of action for several months, and destroyed the ZF gearbox factory.
By the end of the war Maybach had produced over 140,000 engines and 30,000 semi-automatic transmissions for the German Wehrmacht . [ 4 ]
In order to rationalise Germany's military vehicle production, sweeping changes were made to its entire automotive industry. The re-organisation was overseen by Oberbaurat Heinrich Ernst Kniepkamp [ fr ] , head of Wa.Prüf. 6 (Weapons Inspectorate 6, responsible for tanks, armoured vehicles and motorized equipment) of the Heereswaffenamt (HWA). By late October 1935, Maybach had been designated the sole designer and manufacturer of tank and half-track engines for the entire Wehrmacht , with production later outsourced to other firms including its subsidiary Nordbau (Norddeutsche Motorenbau GmbH) in the south-eastern Berlin suburb of Niederschöneweide beside the River Spree . [ 1 ] [ 5 ] [ 6 ]
Maybach AG made very few complete parts of its engines at all. Almost everything was bought in from other suppliers. Its main activity was precision machining of the castings and forgings of its own design, made by outside manufacturers, and producing complete assembled engines on a separate assembly line. [ 7 ] Completely finished crankshafts were supplied by Deutsche Edelstahlwerke AG [ de ] , in Remscheid - de:Hasten . [ 8 ] [ c ] In addition, machined pistons ( Mahle KG ), piston rings, roller and ball bearings, fuel pumps, carburettors ( Solex ), and complete electrical equipment ( Bosch ) were acquired as finished parts from outside sources. [ 7 ]
Although a steady supply of spare parts is essential to an army in the field, the production of complete engines always took priority over providing spares. [ d ] According to Albert Speer , Hitler himself never realised this importance: "One of his worst failings was that he simply did not understand the necessity for supplying the armies with sufficient spare parts." [ 11 ] [ e ]
Germany never achieved the industrial capacity needed to keep its military vehicles running efficiently: when the Russian campaign got underway, the deficiencies of the armaments industry and the organisation of maintenance depots became obvious. [ 12 ] The German armed forces suffered from continual shortages of spare parts for tanks and half-tracks until the end of the war. [ 13 ] When the first Tiger I tanks arrived in Russia in autumn 1942, there was only one spare engine and one transmission for every 10 tanks. A critical lack of spare parts meant that most of them were out of commission within a short period, sometimes for weeks on end. [ 14 ] Despite various attempts at re-organisation, friction between the distribution systems of the German Army ( das Heer ) and the civilian Ministry of Armaments (and from 1944 the ' Rüstungsstab ') often led to confrontation and inefficiency. [ 15 ] Some of this can be blamed on Karl-Otto Saur of the Ministry of Armaments, whose ruthless drive for greater overall production figures tended to override the need for testing and durability concerns, and the manufacture of enough spare parts. [ 16 ]
According to Stieler von Heydekampf , president of the Panzer Kommission from 1943, German tank production was at a major disadvantage throughout the war because the main firms involved were heavy equipment manufacturers. It would have been more effective if the programme had been given to Ford Germany and Opel (owned by General Motors ) because of their real mass production experience, but this was not done because of their American associations. [ 17 ] [ f ]
Maybach's monopoly on engine production proved to be the bottleneck in German tank production. [ 19 ] [ 20 ] From 1942, after the German invasion of the Soviet Union , Maybach started dispersing its manufacturing activities, licensing eight other firms to manufacture its engines. Adler Werke in Frankfurt/Main built the HL42 from January 1942; Saurer Werke in Vienna, Krauss-Maffei (Munich), and Borgward in Bremen were licensed to build the HL62 & HL64; Maschinenfabrik Bahn Bedarf (MBB) in Nordhausen made the HL109, and also the HL120—along with Maybach's subsidiary Nordbau in Berlin and MAN in Nurnberg ; and Auto Union in Chemnitz ( Siegmar Werke ) made HL230s, having tooled up from October 1943–March 1944. [ 21 ] Henschel & Sohn in Kassel made large quantities of major components for Maybach in 1943–1944: 2,434 crankshafts, 1,850 crank cases, 32,121 connecting rods and 8,196 'closing covers' (undefined - maybe valve covers or possibly cylinder heads). [ 22 ]
Maybach from August 1943 also organised 11 of its own dispersal machining sites located from a few miles away to some 60 miles distant; the finished parts were then sent to a designated factory for assembly. These precautions allowed manufacture of complete engines to take place away from Friedrichshafen. [ 23 ] On Hitler's orders in March 1944, the extensive cellars below the town of Leitmeritz (now Litoměřice, Czech Republic ) on the river Elbe were to be used for the anticipated assembly for HL120 and HL230 tank engines, in case a manufacturing plant were to be bombed. [ 24 ]
Despite these precautions, by late 1943 there was still a severe shortage of spare tank engines. [ g ] Rather than concentrate on proven designs, Maybach continued to bring out new, relatively untested models; the wide variety of engine types seriously hampered efforts to fix the multiple defects which Maybach engines developed under combat conditions. [ 14 ] The extreme difficulty of stocking so many spares at the front, several thousand kilometres away from the factory, swiftly led to vehicles being unserviceable for combat. Because the armaments industry was already working at full capacity, it was not possible to completely replace obsolete models with new versions. Instead, the number of tank models and types within each series issued to the field forces increased steadily, which only made the maintenance and repair situation worse. [ 25 ]
Severely damaged tanks from the Russian front were initially shipped back to Germany, or to the Nibelungenwerk or the Vienna Arsenal for repair; [ 26 ] [ 27 ] [ 28 ] but the prospect of inevitable delays often meant that vehicles were instead cannibalised at the front for parts. Often when a new engine was delivered, there was little left except the hull of the tank it was intended for. [ 29 ] Nevertheless, the maintenance crews did their best, often retrieving knocked-out tanks under considerable difficulties. [ h ]
As the war progressed, new Maybach engines tended to be rushed into production, without adequate testing and improvement. As a result, they were viewed as unreliable (although this would be expected of any un-developed engine). [ 31 ] [ i ] All the 325 new Panther tanks delivered to Russia in early 1943 had to be returned because of serious defects in the steering; [ 33 ] they were underpowered by the HL210 P30 engine, and its replacement, the HL230 P30 (which didn't arrive until late 1943) suffered from over-heating, fires in the engine compartment and blown gaskets. [ 34 ]
By way of comparison, the Soviet Army used a single basic engine (the V-12 diesel Kharkiv V-2 ) to power the majority of its tanks – with a few modifications – starting with the BT-7M and its successor the T-34 , [ 35 ] producing 500 hp (370 kW) @ 1800 rpm in 1939; [ 36 ] the SU-85 and SU-100 ; the KV-1 and KV-2 (600 hp with supercharging in 1939); and the IS-2 , ISU-122 and ISU-152 and the T-10 . Maybach didn't produce a more powerful acceptable engine until late 1943 with the HL230 P30.
Starting in March 1944, a series of Allied precision and area bombing raids put the Maybach factory out of action for several months. Those of 27/28 April and 20 July especially inflicted heavy damage on the plant. [ 37 ] However, engine production continued at the various dispersed machining sites and manufacturers. If the various firms making Maybach motors under license had not been in a position to continue producing engines, the German Army's entire tank program would have been seriously jeopardised. [ 38 ]
Although the German Army used various combat vehicles appropriated from other countries , they continued to be powered by their original engines. Maybach engines were fitted to the German fighting vehicles for which they had been designed. [ j ]
All Maybach engines for AFVs which reached series production were gasoline four-stroke water-cooled designs. The firm's managing director, Dr. Karl Maybach (son of the founder Wilhelm Maybach ), had stated that "he was born water cooled and wanted to die water cooled." [ 39 ] [ k ]
Before the war the fuel industry had indicated that petroleum was going to be easier to produce than synthetic diesel, and development of gasoline engines was therefore favoured. By around 1943 the situation had turned around, but by then it was too late to change. [ 42 ] Dr. Ferdinand Porsche had consistently pushed for air-cooled diesels, but his organisation's designs never functioned satisfactorily. [ 43 ] The twin large Porsche gasoline V-10 engines slated for the Tiger (P) never worked satisfactorily, and two over-worked Maybach HL120s were fitted instead to drive the electric generators and final drive motors in the subsequent Ferdinand . [ 44 ]
A number of Maybach motors shared the same basic design but had different engine sizes, the larger engines having bigger cylinders to increase the capacity. Similar engine designs had shared parts lists, e.g. the NL38 and HL42; the HL57 and HL62; and the HL108 and HL120. [ 45 ]
The 6-cylinder Maybach engines used a single Solex 40 JFF II down-draught ( German : Fallstrom ) carburetor , [ 46 ] and earlier V-12s used two. [ 47 ] Later V-12s used Solex 52 JFFs.
A hand-cranked inertia starter ( Schwungkraftanlasser ) was fitted to the V-12 engines to supplement the Bosch 24V electric starter motor (powered by two 12V batteries) in cold weather. [ 48 ]
Maybach used a series of letter codes and numbers to identify specific engine models, namely:
Although these codes usually indicate what ancillary equipment was fitted at the factory (e.g. the HL42 TUKRRM and the HL57 TR), there are some exceptions, discussed below.
The individual engine number and its capacity, the model type, and year of manufacture are hand-stamped on each crankcase. On 6-cylinder models with schnapper magneto ignition, this information is found on the magneto housing: e.g. [ 49 ]
MOTOR N r 730192 4198 ccM. HL42 TUKRM 1943
And on the HL210, stamped at the top end of the crankcase above the flywheel cover: [ 50 ]
M ot. N r. 46302 HL210 P45
This is followed (without space) by the approximate engine capacity (e.g. HL42 = approx. 4.2 litres.)
Compared to the NL motors, the HL (high performance) series had a higher compression ratio , which increased the power output. This advantage was somewhat lost when a mandatory requirement to run on lower-quality OZ 74 (74 octane ) gasoline after October 1938 necessitated the compression ratio of the HL series to be lowered, achieved by fitting shorter pistons and a new cylinder head. [ 51 ] This may partially explain the similar power outputs of engines with different capacities, shown in the table further below.
In addition, 'T' by itself has no meaning; it is always directly followed by either R or U, but 'R' in this position should not be confused with an (R) signifying a V-belt drive for a compressor ( see below ). Furthermore, in some sources engines may be referred to simply as e.g. "a Maybach HL 120 of 300 metric horsepower", [ citation needed ] which indicates that further information is needed to identify the particular model number.
On some engines (e.g. the NL38 TUK) the compressor was an integral part of the engine, driven by internal gears and mounted on top of the cam cover at the flywheel end. The compressor is not specifically indicated in the model number. In similar fashion, on the HL 57 TU and 62 TUK the compressor was located in a gear-driven housing next to the clutch on the inlet side. [ 71 ]
On other models, the compressor was an external belt-driven ancillary denoted by an (R) in the model number (e.g. HL38 TUKR), it was mounted on one or other side of the engine, driven by an extra V-belt at the radiator end. Thus the lack of an (R) in the model number doesn't necessarily mean that a compressor wasn't fitted. The compressor was used to power various types of equipment, including:
All Maybach engines used a Bosch 12-volt magneto for the ignition. There were two main types:
Most models were also fitted with a belt-driven Bosch generator for charging the two 12-volt batteries for the 24-volt electric starter motor; and for 12-volt lighting, etc. On 4- and 6-cylinder engines the generator was usually connected by a short drive shaft to the separate belt-driven coolant pump , located close to the cylindrical oil cooler .
These letters were only used on some models, e.g. HL42 TRKMS, HL45 Z, HL157 P.
The HL230 P30 and P45 appear to fall into this category, being named according to their original project specification: the HL230 P30 was designed to be fitted in the Panther , whose prototype was the 30-ton class VK30.02; and the HL230 P45 went in the Tiger, whose final 45-ton class prototype was numbered VK45.01. [ 89 ]
Between 1934 and 1950, Maybach designed approximately 100 different types of HL engines, of which about 70 reached at least bench testing . Some were 'proof of concept' single-cylinder designs. [ 91 ] Many of these engines were the direct result of orders for an engine of a specific power and physical size, originating from Waffenamt Prüfwesen 6 ('Weapons Testing [division] 6', Wa. Prüf. 6 , responsible for tanks, armoured vehicles and motorized equipment) of the Heereswaffenamt .
Fewer than twenty of these basic designs were actually manufactured as quantity series production engines, [ 91 ] and are shown in the first table. Many these engines were manufactured in their thousands by Maybach and its licensed manufacturers.
The second table lists Maybach engines which, although fully functioning, were only made in small quantities and often assigned to projects in the VK series ( Versuchskampffahrzeug , "research/experimental fighting vehicle"). Others in the second list were intended for tanks and other AFVs which never even left the drawing board , the so-called 'Paper Panzers' such as the Entwicklung series , from de: Entwicklung , "development"). [ 92 ]
Two HL90 P 20-K engines were used in the sole uncompleted prototype of the Räumer S mine clearer. [ 191 ]
A proposed replacement for the Panzer IV had been considered since around 1937. What became the Tiger tank went through a series of specifications, with the final revision (VK 4501) being made in May 1941. [ 206 ] Only a month later, the German armies invading Russia encountered the superior T-34 and KV-1 : by December 1941 a specification for a 30-ton medium tank (which became the Panther) had been proposed as an immediate response to the Soviet tank threat. [ 207 ] [ cq ]
Development of the two tanks continued simultaneously: the Tiger prototype was demonstrated to Hitler on his birthday in April 1942, [ 211 ] and the first of two Panther prototypes was ready in August 1942. [ 207 ]
The weight of the Tiger had increased considerably since its inception, and although it was now considerably heavier than the Panther medium tank, Maybach proposed fitting almost exactly the same 21-litre V-12 650 hp engine in both tanks. To save weight, the cylinder block was cast in aluminium alloy , with cast iron liners. The pistons were made of low-expansion aluminium-silicon alloy with Si content of nearly 20%. [ 212 ] The engine for the original 30-ton Panther project was the Maybach HL210 P30, [ 175 ] while the 45-ton specification for the Tiger received the HL210 P45. [ 171 ] The main visible difference was the arrangement of the coolant ducts exiting the cylinder heads, since the Panther and Tiger had different flows through their radiators. [ cr ]
Quantity series production of the PzKpfw VI Tiger (Ausf. H) with the HL210 P45 engine began in August 1942, [ 211 ] and it is possible that production of the Panther's HL210 P30 was begun at much the same time. The first battalions to be equipped with the Tigers were the 502nd Heavy Panzer Battalion on the Eastern Front near Leningrad , and the 501st Heavy Panzer Battalion which was sent to Tunisia . Unfortunately, it swiftly became apparent that the Tiger was seriously underpowered, and the rush into production of the new engines meant that the inevitable design defects had not been ironed out. Nevertheless, when the new Tigers arrived in Russia, there was only one spare engine and one transmission for every 10 tanks. A critical lack of spare parts meant that most of them were out of commission within a short period. [ 33 ]
The first PzKpfw V Panthers (Ausf. D) were similarly ill-fated; series production began in January 1943, but when they arrived in Russia in the spring the faults (including the steering and leaking engine gaskets) were so egregious that the entire batch had to be returned to Germany. [ 14 ] A special plant for rebuilding the Panthers was established near Berlin. [ 14 ] A report by Oberstleutnant Reinhold, attached to the 4th Panzer Army during Operation Citadel in July 1943, stated: "Mechanical Deficiencies: The cause for motor failures is still not known. It is possibly traceable to the short run-in time and unskilled drivers. Motors were over-revved. This caused overheating and broken connecting rods. In many cases fuel pumps failed. The pump seals leaked and pump membranes were defective. Leaks in oil line and fuel line connections increased the danger of fire." [ 213 ]
Another report from Oberstleutnant Mildebrath for Heinz Guderian , the Generalinspekteur der Panzertruppen in September 1943, about the 96 Panthers of the 2nd Battalion ( Abteilung ) of the 23rd Panzer Regiment, part of the 23rd Panzer Division :
At Kursk, 5–13 July 1943, 25 engines failed within 9 days (these would probably have been HL210 P30s) faults included piston rod bearing damage, broken con rods, damaged pistons, tears (cracks) in the cylinder sleeves, burnt cylinder head gaskets, and water in the exhaust. Also high oil consumption, and spark plugs oiling up. Fuel lines weren't sealed properly, leading to fires in the engine compartment. Final drives were too weak and had a high failure rate. The main clutch was fine except when used for towing, and the gearbox also functioned without problems - it always seems to have worked well, with very few problems ever reported. The running gear also functioned well. [ 215 ]
In the meantime, Maybach re-designed the HL210, replacing the alloy cylinder block with a traditional cast-iron one. Although there was no space for a physically larger engine, the cylinders were capable of being bored out without compromising the engine's integrity. The cast-iron HL230 engines weighed around 1,400 kilograms (3,100 lb), considerably more than the 1,050 kilograms (2,310 lb) of the HL210. [ 216 ] The new HL230 23-litre engines were installed from May 1943 in the latest production Panthers as the P30, and in Tigers as the P45. [ 217 ] [ 218 ] [ 219 ] [ ct ] Although they produced 700PS @3,000 rpm, from November 1943 they were governed at the factory to 2,500 rpm to increase engine life, which limited them to the same 650 PS as the HL210. [ 220 ]
Despite all the changes, the up-engined Panther Ausf. A with the HL230 P30 (which didn't arrive in Russia until late 1943) suffered from over-heating, fires in the engine compartment and blown head gaskets . [ 34 ] The head gasket problem was solved in August 1943 by pressing copper rings into grooves to seal the head. A new design of piston was fitted to the HL230 P45 which reduced the compression ratio slightly. [ 218 ] In November 1943 a governor was installed in the HL230 P45 which limited the maximum revs to 2,500 rpm, and the maximum speed under full load to 38 km/h (24 mph). Some new and rebuilt motors from October had faulty bearings installed causing frequent failures: improved bearings were installed in new HL230 P45s from January 1944. [ 220 ]
As a result of these improvements the Panther became much more reliable. In Nachtrichtenblatt der Panzertruppen ('Newssheet of the Panzer Troops') for March 1944, [ cu ] Guderian could include the combat report of an unnamed Panther battalion (possibly 1/1st Panzer Regiment) which had travelled an average of 700 kilometers per tank, with only 11 engines needing replacement. [ 222 ] And in a situation report to Hitler on late June 1944 on the Battle for Normandy , he comments on the Panther's propensity to catch fire, and the mismatch between the durability of the engine and the transmission: "However, the Panther burns astonishingly quickly. The lifespan of the Panther's engine (1400 to 1500 kilometers) is considerably higher than that of the Panther's final drives. A solution is urgently needed!" [ 223 ] [ 224 ] Such a solution was never found. A French post-war report The Panther 1947 stated that although the engine could last for up to 1500 km, average 1000 km, the final drives only had a fatigue life of 150 km. The engine could be replaced in 8 hours by a trained mechanic Unteroffizier and 8 men with a tripod beam crane or Bergepanther . [ 225 ]
Maybach didn't separate the production statistics of the 210 from the 230. Altogether, production of both types amounted to 153 in 1942, 4,346 in 1943, and 1,785 HL230s up to April 1944. In late April 1944 an Allied bombing raid put the Maybach factory out of action for six months. [ 226 ] Production was transferred to the Auto Union factory in Chemnitz , which delivered 219 HL230 engines to Henschel in 1944. A total of 4,366 HL230s from April for Panthers and Tigers were delivered from April 1944 to 1945. [ 226 ]
Despite their similar appearances, the P30 and P45 versions had numerous small differences. The 230 P30 could be swapped with the P45 from a Tiger, but 105 separate parts needed to be removed from the P45 and replaced by 107 parts from the P30. [ 227 ]
According to the head of Henschel's design office in 1945, the assembly shop felt that the engine layout of the P30 version of the HL230 had much better attributes and was better developed for assembly work than the HL230 P45 fitted to the Tiger Ausf. E. [ 228 ]
Maybach continued to develop increasingly powerful 4-stroke water-cooled gasoline-powered engines during the war. One such Versuchsmotor which never reached series production was the HL234, a development of the HL230. [ cv ]
The intention was to develop a fuel-injected and supercharged engine, but only the fuel injection mechanism (by Bosch) was working by the end of the war. [ 203 ] The engine displaced approximately 23.4 litres, and the un-supercharged version was capable of developing 850 PS @2,800 rpm, with maximum torque of 260 kilogram metres (2,500 N⋅m; 1,900 lb⋅ft) @1,750 rpm [ 229 ] , and 900 PS @3,000 rpm [ 203 ] Only a few pilot fuel-injection engines were built. [ 230 ] The fuel-injected and supercharged version (one engine completed) would hopefully deliver around 1200 PS. [ 231 ]
The main supercharger was to have been driven by its own twin-cylinder supercharged 1 litre engine of 70 PS mounted in the V of the HL234 (where the carburetors were located in a normally-aspirated engine), but this part of the design was never completed. [ cw ] By April 1943 the crankshaft bearings and connecting rods from the HL230 had also been strengthened, and the direct fuel injection system was working - but the supercharger was not yet fully developed. [ 203 ] Other improvements over the HL230 included water-cooled spark plugs; an improved intake manifold for better airflow; and improved exhaust manifold as well. [ 232 ] Instead of coil-type valve springs the HL 234 used much stronger Belleville washers , which reduced valve opening times. [ 233 ] Problems with rubber seals and copper [head] gaskets were solved by adopting designs used in the Rolls-Royce Merlin engine. [ 232 ]
The first HL234 Versuchsmotor was planned to be delivered in early 1945 to the Kummersdorf proving ground and was proposed in January 1945 as an upgraded power plant for the Tiger II , but had not yet been tested in a tank by that date. [ 201 ] It was also proposed for the Panther II at a later prototype stage, but the project was discontinued. [ 202 ] Similarly, the E.50/E.75 tank series for which the engine was also intended were never built before the war's end, with only development of individual components taking place. [ 203 ]
Maybach also developed a smaller 12-litre version on similar lines to the HL234. It weighed 600 kg, developing 500 PS without supercharger and 700 PS at 3,800 rpm supercharged, [ 232 ] but like so many other German war-time projects, it never came to fruition.
An exception to Maybach's detailed naming system described above is the Maybach DSO8 V-12 engine fitted to early Sd.Kfz. 8s . It was derived from the DS7 ( German : Doppel Sechs 7 ) (i.e. Double-Six, 7 litres) fitted in the Maybach Zeppelin luxury car from 1929, a 7.0 litre (6,971 cc) V12 engine that produced 150 horsepower at 2,800 rpm, [ 234 ] and from the later DS8 8-litre (bore x stroke=92*100 mm, [ 235 ] 7977 cc, 486 cubic inches) which developed 200 bhp (149 kW; 203 PS) at 3200 rpm. [ 236 ] The engine block and pistons were made of light aluminium alloy with cast iron liners. [ 235 ] A 1938 Maybach Zeppelin DS8 also fitted with a Maybach Variorex vacuum shift eight-speed gearbox (both the first 8-speed and first 8-speed manual gearbox), sold at auction in 2012 for 1.3 million Euros. [ 237 ]
John Milsom mentions two versions of the DSO8, one with a power output of 150 bhp fitted to the prototype DB ZD5 as early as 1931, and one of 200 bhp found in the early production Sd.Kfz. 8 (DB s 7) from 1934 to 1936. [ 157 ] A DSO8 developing 155 PS @2600 rpm was also recommended for export models of the Panzer III MKA ("mittlerer Kampfwagen fur Ausland") in August 1937, since the proposed 200 PS Maybach HL76 was "slow to come into production", [ 238 ] and may never have reached series production at all.
The DSO8 also powered three Swedish Stridsvagn m/31 prototypes in the early 1930s. A 150 hp DSO8 is also found in the Strv FM/31 Landsverk L-30 dating from 1931, examples of both are preserved in the Arsenalen Försvarsfordonsmuseum in Strängnäs , central Sweden. [ 239 ] [ 240 ] [ cx ]
German WWII half-track prime mover numbering may appear not to be strictly logical: the two smallest vehicles were introduced after most of the larger artillery tractors were in production. [ 241 ] [ cy ] In ascending order of engine size and therefore towing capacity, they were designed to tow the following: [ 242 ]
As Maybach designed new, more powerful engines, all these vehicle types received at least two and up to four different engine models during production of the latest batches. There remained the necessity of attempting to produce either spare parts or complete new engines, just to keep the older vehicles running. | https://en.wikipedia.org/wiki/List_of_WWII_Maybach_engines |
YouTube is an online video sharing platform owned by Google , founded on February 14, 2005, by Steve Chen , Chad Hurley , and Jawed Karim , and headquartered in San Bruno, California , United States. It is the second-most visited website in the world, after Google Search .
It offers different features based on user verification, such as standard or basic features like uploading videos, creating playlists, and using YouTube Music , with limits based on daily activity (verification via phone number or channel history increases feature availability and daily usage limits); intermediate or additional features like longer videos (over 15 minutes), live streaming, custom thumbnails, and creating podcasts; advanced features like content ID appeals, embedding live streams, applying for monetization, clickable links, adding chapters, and pinning comments on videos or posts. [ 1 ]
As of October 2024 it includes multitask with the improved miniplayer, build, share, and vote on favorite YouTube playlists, set bedtime with Sleep Timer, and an upgrade on YouTube TV . [ 2 ]
YouTube primarily uses the VP9 and H.264/MPEG-4 AVC video codecs, and the Dynamic Adaptive Streaming over HTTP protocol. [ 3 ] By January 2019, YouTube had begun rolling out videos in AV1 format, since then videos which are popular have it. [ 4 ] [ 5 ] In 2021 it was reported that the company was considering requiring AV1 in streaming hardware in order to decrease bandwidth and increase quality. [ 6 ] For stereo, video is usually streamed alongside the Opus or AAC audio codecs. For 5.1 sound, Dolby Digital and Dolby Digital Plus , and rarely DTS Express or AAC is used. Additionally, some videos may include Eclipsa audio, which combines Opus with IAMF (Immersive Audio Model and Format). [ 7 ] Certain music includes HE-AAC , which is exclusively available on YouTube Music . Additionally, some videos may have separate audio streams with Dynamic Range Compression . [ 8 ] [ 9 ] [ 10 ]
At launch in 2005, viewing YouTube videos on a personal computer required the Adobe Flash Player plug-in to be installed in the browser. [ 11 ] MPEG-4 Part 2 streams contained within 3GP containers were also provided for low bandwidth connections. [ 8 ] In January 2010, YouTube launched an experimental version of the site that used the built-in multimedia capabilities of Web browsers supporting HTML video . [ 12 ] This allowed videos to be viewed without requiring Adobe Flash Player or any other plug-in to be installed. [ 13 ] On January 27, 2015, YouTube announced that HTML video would be the default playback method on supported browsers . [ 12 ] HTML video streams use Dynamic Adaptive Streaming over HTTP (MPEG-DASH), an HTTP-based adaptive bit-rate streaming solution optimizes the bitrate and quality for the available network. [ 14 ]
The platform can serve videos at optionally lower resolution levels starting at 144p for smoother playback in areas and countries with limited Internet speeds , improving compatibility, as well as for the preservation of limited cellular data plans . The resolution can be adjusted automatically based on detected connection speed or set manually. [ 15 ] [ 16 ]
From 2008 to 2017, users could add "annotations" to their videos, such as pop-up text messages and hyperlinks, which allowed for interactive videos . By 2019, all annotations had been removed from videos, breaking some videos that depended on the feature. YouTube introduced standardized widgets intended to replace annotations in a cross-platform manner, including "end screens" (a customizable array of thumbnails for specified videos displayed near the end of the video). [ 17 ] [ 18 ] [ 19 ]
In 2018, YouTube became an International Standard Name Identifier (ISNI) registry, and announced its intention to begin creating ISNI identifiers to uniquely identify the musicians whose videos it features. [ 20 ]
Users can verify their account, normally through a mobile phone, to gain the ability to upload videos up to 12 hours in length, as well as produce live streams. [ 21 ] [ 22 ] Users who have built sufficient channel history and have a good track record of complying with the site's Community Guidelines will also gain access to these aforementioned features as well. [ 23 ] When YouTube was launched in 2005, it was possible to upload longer videos, but a 10-minute limit was introduced in March 2006 after YouTube found that the majority of videos exceeding this length were unauthorized uploads of television shows and films. [ 24 ] The 10-minute limit was increased to 15 minutes in July 2010. [ 25 ] Videos can be at most 256 GB in size or 12 hours, whichever is less. [ 21 ] As of 2021 [update] , automatic closed captions using speech recognition technology when a video is uploaded are available in 13 languages, and can be machine-translated during playback. [ 26 ]
YouTube also offers manual closed captioning as part of its creator studio. [ 27 ] YouTube formerly offered a 'Community Captions' feature, where viewers could write and submit captions for public display upon approval by the video uploader, but this was deprecated in September 2020. [ 28 ]
YouTube accepts the most common container formats , including MP4 , Matroska , FLV , AVI , WebM , 3GP , MPEG-PS , and the QuickTime File Format . Some intermediate video formats (i.e., primarily used for professional video editing, not for final delivery or storage) are also accepted, such as ProRes . [ 29 ] YouTube provides recommended encoding settings. [ 30 ]
Each video is identified by an eleven-character case-sensitive alphanumerical Base64 string in the Uniform Resource Locator (URL) which can contain letters, digits, an underscore ( _ ), and a dash ( - ). [ 31 ]
In 2018, YouTube added a feature called Premiere which displays a notification to the user mentioning when the video will be available for the first time, like for a live stream but with a prerecorded video. When the scheduled time arrives, the video is aired as a live broadcast with a two-minute countdown. Optionally, a premiere can be initiated immediately. [ 32 ]
YouTube originally offered videos at only one quality level, displayed at a resolution of 320×240 pixels using the Sorenson Spark codec (a variant of H.263 ), [ 33 ] [ 34 ] with mono MP3 audio. [ 35 ] In June 2007, YouTube added an option to watch videos in 3GP format on mobile phones. [ 36 ] In March 2008, a high-quality mode was added, which increased the resolution to 480×360 pixels. [ 37 ] In December 2008, 720p HD support was added. At the time of the 720p launch, the YouTube player was changed from a 4:3 aspect ratio to a widescreen 16:9 . [ 38 ] With this new feature, YouTube began a switchover to H.264/MPEG-4 AVC as its default video compression format. In November 2009, 1080p HD support was added. In July 2010, YouTube announced that it had launched a range of videos in 4K format, which allows a resolution of up to 4096×3072 pixels. [ 39 ] [ 40 ] In July 2010, support for 2160p UHD was added, with the videos playing at 3840 × 2160 pixels. [ 41 ] In June 2014, YouTube began to deploy support for high frame rate videos up to 60 frames per second (as opposed to 30 before), becoming available for user uploads in October. YouTube stated that this would enhance "motion-intensive" videos, such as video game footage. [ 42 ] [ 43 ] [ 44 ] [ 45 ] In June 2015, support for 8K resolution was added, with the videos playing at 7680×4320 pixels. [ 46 ] In November 2016, support for HDR video was added which can be encoded with hybrid log–gamma (HLG) or perceptual quantizer (PQ). [ 47 ] HDR video can be encoded with the Rec. 2020 color space. [ 48 ]
YouTube videos are available in a range of quality levels. Viewers only indirectly influence the video quality. In the mobile apps, users choose between "Auto", which adjusts resolution based on the internet connection, "High Picture Quality" which will prioritize playing high-quality video, "Data saver" which will sacrifice video quality in favor of low data usage and "Advanced" which lets the user choose a stream resolution. [ 49 ] On desktop, users choose between "Auto" and a specific resolution. [ 50 ] It is not possible for the viewer to directly choose a higher bitrate (quality) for any selected resolution.
Since 2009, viewers have had the ability to watch 3D videos. [ 51 ] In 2015, YouTube began natively supporting 360-degree video . Since April 2016, it allowed live streaming 360° video, and both normal and 360° video at up to 1440p, and since November 2016 both at up to 4K (2160p) resolution. [ 52 ] [ 53 ] [ 54 ] Citing the limited number of users who watched more than 90-degrees, it began supporting an alternative stereoscopic video format known as VR180 which it said was easier to produce, [ 55 ] which allows users to watch any video using virtual reality headsets. [ 56 ]
In response to increased viewership during the COVID-19 pandemic, YouTube temporarily downgraded the quality of its videos. [ 57 ] [ 58 ] YouTube developed its own chip, called "Argos", to help with encoding higher resolution videos in 2021. [ 59 ]
In April 2023, YouTube began offering some videos in an enhanced bitrate " 1080p Premium" option for YouTube Premium subscribers on iOS. [ 60 ] In August 2023, the feature became available to subscribers on desktop platforms. [ 61 ]
In certain cases, YouTube allows the uploader to upgrade the quality of videos uploaded a long time ago in poor quality. One such partnership with Universal Music Group included remasters of 1,000 music videos. [ 62 ]
YouTube carried out early experiments with live streaming , including its YouTube Live event in 2008, [ 63 ] a concert by U2 in 2009, and a question-and-answer session with US President Barack Obama in February 2010. [ 64 ] These tests had relied on technology from 3rd-party partners, but in September 2010, YouTube began testing its own live streaming infrastructure. [ 65 ] In April 2011, YouTube announced the rollout of YouTube Live . The creation of live streams was initially limited to select partners. [ 66 ] It was used for real-time broadcasting of events such as the 2012 Olympics in London. [ 67 ] In October 2012, more than 8 million people watched Felix Baumgartner 's jump from the edge of space as a live stream on YouTube. [ 68 ]
In May 2013, creation of live streams was opened to verified users with at least 1,000 subscribers; in August of the same year the number was reduced to 100 subscribers, [ 69 ] and in December the limit was removed. [ 70 ] In February 2017, live streaming was introduced to the official YouTube mobile app. Live streaming via mobile was initially restricted to users with at least 10,000 subscribers, [ 71 ] but as of mid-2017 it has been reduced to 100 subscribers. [ 72 ] Live streams support HDR, can be up to 4K resolution at 60 fps, and also support 360° video. [ 53 ] [ 73 ]
Most videos enable users to leave comments , which have attracted attention for the negative aspects of their form and content. [ specify ] In 2006, Time praised Web 2.0 for enabling "community and collaboration on a scale never seen before", and added that YouTube "harnesses the stupidity of crowds as well as its wisdom. Some of the comments on YouTube make you weep for the future of humanity just for the spelling alone, never mind the obscenity and the naked hatred". [ 74 ] The Guardian in 2009 described users' comments on YouTube as: [ 75 ]
Juvenile, aggressive, misspelt, sexist , homophobic , swinging from raging at the contents of a video to providing a pointlessly detailed description followed by a LOL , YouTube comments are a hotbed of infantile debate and unashamed ignorance—with the occasional burst of wit shining through.
The Daily Telegraph commented in September 2008, that YouTube was "notorious" for "some of the most confrontational and ill-formed comment exchanges on the internet", and reported on YouTube Comment Snob, "a new piece of software that blocks rude and illiterate posts". [ 76 ] The Huffington Post noted in April 2012 that finding comments on YouTube that appear " offensive , stupid and crass" to the "vast majority" of the people is hardly difficult. [ 77 ]
Google subsequently implemented a comment system oriented on Google+ on November 6, 2013, that required all YouTube users to use a Google+ account to comment on videos. The stated motivation for the change was giving creators more power to moderate and block comments, thereby addressing frequent criticisms of their quality and tone. [ 78 ] The new system restored the ability to include URLs in comments, which had previously been removed due to problems with abuse. [ 79 ] [ 80 ] In response, YouTube co-founder Jawed Karim posted the question "why the fuck do I need a google+ account to comment on a video?" on his YouTube channel to express his negative opinion of the change. [ 81 ] The official YouTube announcement [ 82 ] received 20,097 "thumbs down" votes and generated more than 32,000 comments in two days. [ 83 ] Writing in the Newsday blog Silicon Island, Chase Melvin noted that "Google+ is nowhere near as popular a social media network like Facebook , but it's essentially being forced upon millions of YouTube users who don't want to lose their ability to comment on videos" and added that "Discussion forums across the Internet are already bursting with the outcry against the new comment system". In the same article Melvin goes on to say: [ 84 ]
Perhaps user complaints are justified, but the idea of revamping the old system isn't so bad.
Think of the crude, misogynistic and racially-charged mudslinging that has transpired over the last eight years on YouTube without any discernible moderation. Isn't any attempt to curb unidentified libelers worth a shot? The system is far from perfect, but Google should be lauded for trying to alleviate some of the damage caused by irate YouTubers hiding behind animosity and anonymity.
Later, on July 27, 2015, Google announced in a blog post that it would be removing the requirement to sign up to a Google+ account to post comments to YouTube. [ 85 ] On November 3, 2016, YouTube announced a trial scheme which allows the creators of videos to decide whether to approve, hide or report the comments posted on videos based on an algorithm that detects potentially offensive comments. [ 86 ] Creators may also choose to keep or delete comments with links or hashtags to combat spam. They can also allow other users to moderate their comments. [ 87 ]
In December 2020, it was reported that YouTube would launch a new feature that will warn users who post a comment that "may be offensive to others." [ 88 ] [ 89 ]
officially known as Posts since January 2025, is a feature that added on September 13, 2016, YouTube launched a public beta of Community, a social media -based feature that allows users to post text, images (including GIFs ), live videos and others in a separate "Community" tab on their channel. [ 90 ] Prior to the release, several creators had been consulted to suggest tools Posts could incorporate that they would find useful; these YouTubers included Vlogbrothers , AsapScience , Lilly Singh , The Game Theorists , Karmin , The Key of Awesome , The Kloons, Peter Hollens , Rosianna Halse Rojas , Sam Tsui , Threadbanger and Vsauce3 . [ 91 ] [ non-primary source needed ]
After the feature has been officially released, the community post feature gets activated automatically for every channel that passes a specific threshold of subscriber counts or already has more subscribers. This threshold was lowered over time, [ when? ] from 10,000 subscribers to 1500 subscribers, to 1000 subscribers, [ 92 ] [ non-primary source needed ] to 500 subscribers. [ 93 ]
Channels that the community tab becomes enabled for, get their channel discussions (previously known as channel comments) permanently erased, instead of co-existing or migrating. [ 94 ] [ non-primary source needed ]
Experimental features of YouTube could be accessed in an area of the site formerly named TestTube . [ 95 ] [ 96 ] For example, in October 2009, a comment search feature accessible under /comment_search was implemented as part of this program, however the feature was later removed. [ 97 ] Later the same year, YouTube Feather was introduced as a "lightweight" alternative website for countries with limited internet speeds. [ 98 ] Following the transition to the Polymer layout, TestTube was disabled, and the URL redirects to video playback settings. TestTube was replaced by a new system that requires users to be subscribed to YouTube Premium in order to enable or disable experiments.
YouTube offers users the ability to view its videos on web pages outside their website. Each YouTube video is accompanied by a piece of HTML that can be used to embed it on any page on the Web. [ 99 ] This functionality is often used to embed YouTube videos in social networking pages and blogs. Users wishing to post a video discussing, inspired by, or related to another user's video can make a "video response". The eleven character YouTube video identifier (64 possible characters used in each position), allows for a theoretical maximum of 64 11 or around 73.8 quintillion (73.8 billion billion) unique ids.
YouTube announced that it would remove video responses for being an underused feature on August 27, 2013. [ 100 ] Embedding, rating, commenting and response posting can be disabled by the video owner. [ 101 ] YouTube does not usually offer a download link for its videos, and intends for them to be viewed through its website interface. [ 102 ] A small number of videos can be downloaded as MP4 files. [ 103 ] Numerous third-party web sites, applications and browser plug-ins allow users to download YouTube videos. [ 104 ]
In February 2009, YouTube announced a test service, allowing some partners to offer video downloads for free or for a fee paid through Google Checkout . [ 105 ] In June 2012, Google sent cease and desist letters threatening legal action against several websites offering online download and conversion of YouTube videos. [ 106 ] In response, Zamzar removed the ability to download YouTube videos from its site. [ 107 ] Users retain copyright of their own work under the default Standard YouTube License, [ 108 ] but have the option to grant certain usage rights under any public copyright license they choose.
Since July 2012, it has been possible to select a Creative Commons attribution license as the default, allowing other users to reuse and remix the material. [ 109 ]
Most modern smartphones are capable of accessing YouTube videos, either within an application or through an optimized website. YouTube Mobile was launched in June 2007, using RTSP streaming for the video. [ 110 ] Not all of YouTube's videos are available on the mobile version of the site. [ 111 ]
Since June 2007, YouTube's videos have been available for viewing on a range of Apple products. This required YouTube's content to be transcoded into Apple's preferred video standard, H.264 , a process that took several months. YouTube videos can be viewed on devices including Apple TV , iPod Touch and the iPhone . [ 112 ]
The mobile version of the site was relaunched based on HTML video in July 2010, avoiding the need to use Adobe Flash Player and optimized for use with touch screen controls. [ 113 ] The mobile version is also available as an app for the Android platform. [ 114 ] [ 115 ]
In September 2012, YouTube launched its first app for the iPhone, following the decision to drop YouTube as one of the preloaded apps in the iPhone 5 and iOS 6 operating system. [ 116 ] According to GlobalWebIndex , YouTube was used by 35% of smartphone users between April and June 2013, making it the third-most used app. [ 117 ]
A TiVo service update in July 2008 allowed the system to search and play YouTube videos. [ 118 ]
In January 2009, YouTube launched "YouTube for TV", a version of the website tailored for set-top boxes and other TV-based media devices with web browsers, initially allowing its videos to be viewed on the PlayStation 3 and Wii video game consoles . [ 119 ] [ 120 ]
During the month of June that same year, YouTube XL was introduced, which has a simplified interface designed for viewing on a standard television screen. [ 121 ] YouTube is also available as an app on Xbox Live . [ 122 ]
On November 15, 2012, Google launched an official app for the Wii, allowing users to watch YouTube videos from the Wii channel. [ 123 ] An app was available for Wii U and Nintendo 3DS , but the latter was discontinued in August 2019. [ 124 ] Videos can also be viewed on the Wii U Internet Browser using HTML video. [ 125 ] [ non-primary source needed ] Google made YouTube available on the Roku player on December 17, 2013, [ 126 ] and, in October 2014, the Sony PlayStation 4 . [ 127 ]
YouTube launched as a downloadable app for the Nintendo Switch in November 2018. [ 128 ]
In early years of operation, Google faced some criticism for 'encouraging the dominance of US values', by prioritising English over other languages. On June 19, 2007, at a conference in Paris, Google CEO Eric Schmidt launched YouTube localization , with stated aims including customizing the YouTube experience by country, including country-specific comments, metrics, and video rankings. From 2007, YouTube's localization was rolled out. [ 129 ] [ 130 ]
A 2015 report on YouTube's localization showed it to be continuing, and expanding. [ 131 ] In February 2023, YouTube made it possible to upload a single video in multiple languages. Prior to 2023, the only option for YouTubers to broaden their content's reach to audiences speaking different languages was to launch an entirely separate secondary channel for each language and upload dubbed versions of their videos across all those channels. MrBeast called multi-language dub tracks a “giant win” for creators. With the introduction of the dubbing localization option, many creators switched from uploading to separate channels to uploading to their main channel with dubbed versions. [ 132 ]
In September 2024, YouTube announced the expansion of auto dubbing feature, which generates translated audio tracks in other languages to make the creator's videos more accessible to international viewers, to more markets and languages. The feature was originally announced in 2022 as Aloud. [ 133 ]
As of 2024, the interface of YouTube is available with localized versions in 109 countries, two territories ( Hong Kong & Puerto Rico ) and a worldwide version [ 134 ] and continues to extend the availability of its localized version to additional countries and regions. [ 135 ]
If YouTube is unable to identify a specific country or region according to the IP address, the default location is the United States. However, YouTube offers language and content preferences for all accessible countries, regions, and languages. [ 136 ]
The YouTube interface suggests which local version should be chosen based on the IP address of the user. In some cases, the message "This video is not available in your country" may appear because of copyright restrictions or inappropriate content. [ 187 ] The interface of the YouTube website is available in 76 language versions, including Amharic, Albanian, Armenian, Burmese, Haitian Creole, Kyrgyz, Malagasy, Mongolian, Persian, Samoan, Somali and Uzbek, which do not have local channel versions. Access to YouTube was blocked in Turkey between 2008 and 2010, following controversy over the posting of videos deemed insulting to Mustafa Kemal Atatürk and some material offensive to Muslims. [ 188 ] [ 189 ] In October 2012, a local version of YouTube was launched in Turkey, with the domain youtube.com.tr . The local version is subject to the content regulations found in Turkish law. [ 190 ] In March 2009, a dispute between YouTube and the British royalty collection agency PRS for Music led to premium music videos being blocked for YouTube users in the United Kingdom. The removal of videos posted by the major record companies occurred after failure to reach an agreement on a licensing deal. The dispute was resolved in September 2009. [ 191 ] In April 2009, a similar dispute led to the removal of premium music videos for users in Germany. [ 192 ] | https://en.wikipedia.org/wiki/List_of_YouTube_features |
Abstractions are fundamental building blocks of computer science, enabling complex systems and ideas to be simplified into more manageable and relatable concepts.
General programming abstractions are foundational concepts that underlie virtually all of the programming tasks that software developers engage in. By providing a layer of separation from the specifics of the underlying hardware and system details, these abstractions allow for the creation of complex logic in a more approachable and manageable form. They emerge as a consensus on best practices for expressing and solving programming problems in efficient and logically sound ways. From the simplicity of a variable to the structured flow of control structures, these abstractions are the building blocks that constitute high-level programming languages and give rise to detailed software implementations.
In the context of data structures, the term "abstraction" refers to the way in which a data structure represents and organizes data. Each data structure provides a particular way of organizing data in memory so that it can be accessed and modified according to specific rules. The data structure itself is an abstraction because it hides the details of how the data is stored in memory and provides a set of operations or interfaces for working with the data (e.g., push and pop for a stack, insert and delete for a binary search tree).
In the world of functional programming, abstraction is not just a tool but a core principle that influences the entire programming model. The abstractions used in functional programming are designed to enhance expressiveness, provide greater modularity, and enable transformative operations that are both concise and predictable. By treating computation as the evaluation of mathematical functions, functional programming moves away from the mutable state and side effects that are typical in imperative programming, presenting a declarative approach to problem-solving.
Concurrency models are critical abstractions in computer science that facilitate the management of multiple processes or threads executing simultaneously. These models provide the architectural framework needed to handle concurrent operations efficiently and safely in applications ranging from operating systems to high-throughput data processing and network servers. The key challenge they address is the coordination of computational tasks that can potentially interfere with one another, ensuring data integrity and optimizing resource usage without sacrificing performance.
Design patterns in computer science represent abstract solutions to common software design problems. While they are not abstractions in the same sense as data structures or mathematical concepts, design patterns provide a high-level language for software developers to communicate and implement solutions in a consistent and recognizable way.
Each design pattern abstracts the complexity of a particular design scenario or problem by providing a tested, proven development paradigm.
Programming paradigms constitute the theoretical frameworks that shape the way software constructs are created and executed. Each paradigm embodies a unique approach to organizing and structuring programming logic, often promoting particular forms of abstraction and compositional structures that align with their underlying principles.
Software engineering abstractions are conceptual tools that simplify the complex reality of software systems, enabling developers to focus on high-level problems and manage software complexity. These abstractions are often about hiding the underlying implementation details through encapsulation, defining clear interfaces, and establishing interaction protocols.
Textbook reference: | https://en.wikipedia.org/wiki/List_of_abstractions_(computer_science) |
The following list of accelerator mass spectrometry facilities includes research centers that employ accelerator mass spectrometry (AMS).
Accelerator mass spectrometry is a form of mass spectrometry that accelerates ions to extraordinarily high kinetic energies before mass analysis. | https://en.wikipedia.org/wiki/List_of_accelerator_mass_spectrometry_facilities |
An accidental explosion of ammunition , during transport or storage, can be lethal and have far-reaching affects, especially on the population and environment around it. Between 1997 and 2007, there were 120 accidental ammunition storage explosions, killing more than 3,500 people. [ 1 ] | https://en.wikipedia.org/wiki/List_of_accidents_and_incidents_involving_transport_or_storage_of_ammunition |
Hewlett-Packard , commonly referred to as HP, was an electronics technology company based in Palo Alto, California . Before its 2015 split into two companies, it was known as a leading developer and manufacturer of personal computers, enterprise servers, storage devices, networking products, software, and a range of printers and other imaging products, as well as a provider of services and consulting. In 2012, HP was the largest technology company in the world in terms of revenue, ranking 10th in the Fortune Global 500 . [ 1 ]
The company was founded by Bill Hewlett and Dave Packard in a small garage on January 1, 1939, initially producing a line of electronic test and measurement equipment. [ 2 ]
As of 2012, Hewlett-Packard had made a total of 129 acquisitions since 1986; [a] [ 3 ] The majority of companies acquired by HP were based in the United States.
Its first acquisition was the FL Moseley Company in 1958. This move enabled HP to enter the plotter market, the precursor to its leading role in the printer business. [ 4 ] In 1989, HP purchased Apollo Computer for US$476 million, [ 5 ] [ 6 ] enabling HP to become the largest supplier of computer workstations . [ 5 ] In 1995, the company bought another computer manufacturer, Convex Computer , for $150 million. [ 7 ] In 2000, HP spun off its early measurement, chemical and medical businesses into an independent company named Agilent Technologies . [ 8 ] [ 9 ] The company's largest acquisition came in 2002, when it merged with Compaq , a personal computer manufacturer, for $25 billion. [ 10 ] [ 11 ] The combined company overtook Dell for the largest share of the personal computer market worldwide in the second quarter. [ 12 ] Their last pre-split acquisition in the enterprise networking segment was Aruba Networks in March 2015 for $3 billion.
Within IT networking hardware and storage market segments, HP made acquisitions worth over $15 billion, including the 3PAR and 3COM acquisitions made in 2010, totaling over $5 billion. Its largest IT services and consulting acquisition was Electronic Data Systems in 2008 for $13.9 billion.
In the software products market segment, a stream of acquisitions helped strengthen HP's position. [ 13 ] The largest software company purchased prior to 2011 was Mercury Interactive for $4.5 billion. This acquisition doubled the size of HP's software business to more than $2 billion in annual revenue. [ 14 ]
In 2012 and 2013, HP had no acquisitions in any of its business segments as the firm was dealing with the aftermath of an $8.8 billion write-off, suffered as a result of its acquisition of British software company Autonomy Corporation for $11 billion in 2011. In 2014, HP returned to the acquisition market by acquiring computer networking software company Shunra.
On October 6, 2014, HP announced that it would split into two companies, Hewlett Packard Enterprise and HP Inc . The former focuses on enterprise infrastructure hardware, software and services, whilst the latter focuses on consumer markets with PCs and printers. On November 1, 2015, they became separate companies.
Each acquisition was for the respective company in its entirety, unless otherwise specified. The agreement date listed is the date of the agreement between HP and the subject of the acquisition, while the acquisition date listed is the exact date in which the acquisition completes. The value of each acquisition is usually the one listed at the time of the announcement. If the value of an acquisition is not listed, then it is undisclosed.
[ 60 ] | https://en.wikipedia.org/wiki/List_of_acquisitions_by_Hewlett-Packard |
This is a static list of 599 additives that could be added to tobacco cigarettes in 1994. The ABC News program Day One first released the list to the public on March 7, 1994. [ 1 ] It was submitted to the United States Department of Health and Human Services in April 1994. [ 2 ] [ 3 ] [ 4 ] They are also listed in the documents that are part of the 1998 Tobacco Master Settlement Agreement . [ 5 ] It applies, as documented, only to American manufactured cigarettes intended for distribution within the United States by the listed companies. The five major tobacco companies that reported the information were:
One significant issue is that while all these chemical compounds have been approved as additives to food , they were not tested by burning . Burning changes the properties of chemicals. Burning creates additional toxic compounds, including carcinogens. [ 6 ] According to the U.S. National Cancer Institute : "Of the more than 7,000 chemicals in tobacco smoke, at least 250 are known to be harmful, including hydrogen cyanide, carbon monoxide, and ammonia. Among the 250 known harmful chemicals in tobacco smoke, at least 69 can cause cancer." [ 7 ] [ 2 ] [ 8 ] [ 9 ] See: Health effects of tobacco smoking and List of cigarette smoke carcinogens .
Although many of these additives are used in making cigarettes, each cigarette does not contain all of these additives. Some of these additives are found in cigarettes outside the USA too. [ 10 ]
Some American brands are sold in other nations. For example: Marlboro , L&M , Winston , Chesterfield , Kent , and Newport . [ 11 ] [ 12 ] | https://en.wikipedia.org/wiki/List_of_additives_in_cigarettes |
The differences between additives for fracking in different countries are the type of chemicals used (hazardous, non-hazardous), the disclosure of chemicals and the composition of fracturing fluid. In 2010, Halliburton announced the creation of food additive based hydraulic fracturing fluid in response to calls for transparency and demand for a "more environmentally friendly" unconventional hydrocarbon production. [ 1 ]
In Europe, Poland, Norway and Germany have the largest reserves of shale gas, and drillings are underway. [ 2 ]
In the United Kingdom, the environmental regulator permits only chemical additives which are classed as non hazardous to groundwater for fracturing fluids. [ 3 ] [ 4 ] [ 5 ] Operators are required to disclose the content of hydraulic fracturing fluids to the relevant environment agency [ 6 ] while the composition must be disclosed if the regulator demands it. [ 7 ] The permitted additives for hydraulic fracturing fluid include polycrylamide , hydrochloric acid and a biocide .
In the US, about 750 compounds have been listed as additives for hydraulic fracturing, also known as ingredients of pressurized fracking fluid, [ 9 ] in an industry report to the US Congress in 2011 [ 10 ] [ 11 ] The following is a partial list of the chemical constituents in additives that are used or may have been used in fracturing operations. [ 12 ] | https://en.wikipedia.org/wiki/List_of_additives_used_for_fracking |
Escitalopram ( / ˌ ɛ s ə ˈ t æ l ə ˌ p r æ m / ⓘ eh-sə- TA -lə-pram ), sold under the brand names Lexapro and Cipralex , among others, is an antidepressant medication of the selective serotonin reuptake inhibitor (SSRI) class. [ 8 ] It is mainly used to treat major depressive disorder , [ 8 ] generalized anxiety disorder , [ 8 ] panic disorder , obsessive–compulsive disorder (OCD), and social anxiety disorder . Escitalopram is taken by mouth . [ 8 ] For commercial use, it is formulated as an oxalate salt exclusively.
Common side effects include headache , nausea , sexual problems , mild sedation , and trouble sleeping . [ 8 ] More serious side effects may include suicidal thoughts in people up to the age of 24 years. [ 8 ] It is unclear if use during pregnancy or breastfeeding is safe. [ 9 ] Escitalopram is the ( S )- enantiomer of citalopram (which exists as a racemate ), hence the name es-citalopram. [ 8 ]
Escitalopram was approved for medical use in the United States in 2002. [ 8 ] Escitalopram is rarely replaced by twice the dose of citalopram ; escitalopram is safer and more effective. [ 10 ] It is on the World Health Organization's List of Essential Medicines . [ 11 ] In 2022, it was the second most prescribed antidepressant and fifteenth most commonly prescribed medication in the United States, with more than 30 million prescriptions. [ 12 ] [ 13 ] In Australia, it was one of the top 10 most prescribed medications between 2017 and 2023. [ 14 ]
Other first-line SSRIs that have similar results include sertraline , paroxetine and fluoxetine among others.
Escitalopram is approved by the US Food and Drug Administration (FDA) for the treatment of major depressive disorder in adolescents and adults, and generalized anxiety disorder (GAD) in adults, in dosage from 5 to 20mg. [ 8 ] [ 15 ] In European countries including the United Kingdom, it is approved for depression and anxiety disorders ; these include: generalized anxiety disorder, social anxiety disorder (SAD), obsessive–compulsive disorder (OCD), and panic disorder with or without agoraphobia . In Australia it is approved for major depressive disorder. [ 16 ] [ 17 ] [ 18 ]
Escitalopram is among the most effective and well-tolerated antidepressants for the short-term treatment of major depressive disorder in adults. [ 19 ] [ 20 ] It also seems to be the safest one to give to children and adolescents. [ 21 ] [ 22 ]
Controversy existed regarding the effectiveness of escitalopram compared with its predecessor, citalopram. The importance of this issue followed from the greater cost of escitalopram relative to the generic mixture of isomers of citalopram, prior to the expiration of the escitalopram patent in 2012, which led to charges of evergreening . Accordingly, this issue has been examined in at least 10 different systematic reviews and meta analyses. As of 2012 [update] , reviews had concluded (with caveats in some cases) that escitalopram is modestly superior to citalopram in efficacy and tolerability. [ 23 ] [ 24 ] [ 25 ] [ 26 ]
Escitalopram appears to be effective in treating generalized anxiety disorder, with relapse on escitalopram at 20% rather than placebo at 50%, which translates to a number needed to treat of 3.33. [ 27 ] [ 28 ] Escitalopram appears effective in treating social anxiety disorder as well. [ 29 ]
Escitalopram may reduce premenstrual symptoms in women with premenstrual syndrome and premenstrual dysphoric disorder . It seems to be more effective when taken continuously compared to luteal phase administration. [ 30 ] It is also occasionally prescribed off-label for insomnia secondary to a mental disorder, and vasomotor symptoms (hot flashes) associated with menopause. [ 15 ]
Escitalopram has a relatively favorable side effect profile compared to other antidepressants medication. Some of the most common side effect in order of frequency are, headache, nausea, somnolence, insomnia, dry mouth, fatigue, decreased libido, constipation, and flu-like symptoms [ 31 ]
Similar to other SSRIs , escitalopram has been shown to affect sexual function, causing delayed ejaculation , and anorgasmia . [ 32 ] [ 33 ]
There is also evidence that SSRIs are correlated with an increase in suicidal ideation in certain individuals. An analysis conducted by the FDA found a statistically insignificant 1.5 to 2.4-fold (depending on the statistical technique used) increase of suicidality among the adults treated with escitalopram for psychiatric indications. [ 34 ] [ 35 ] [ 36 ] The authors of a related study note the general problem with statistical approaches: due to the rarity of suicidal events in clinical trials, it is hard to draw firm conclusions with a sample smaller than two million patients. [ 37 ]
Citalopram and escitalopram are associated with a mild dose-dependent QT interval prolongation, [ 38 ] which is a measure of how rapidly the heart muscle repolarizes after each heartbeat. Prolongation of the QT interval is a risk factor for torsades de pointes (TdP), a heart rhythm disturbance that is sometimes fatal. Despite the observed change in the QT interval, the risk of TdP from escitalopram appears to be quite low, and it is similar to other antidepressants that are not known to affect the QT interval. A 2013 review [ 39 ] discusses several reasons to be optimistic about the safety of escitalopram. It references a crossover study in which 113 subjects were each given four different treatments in randomized order: placebo, 10 mg/day escitalopram, 30 mg/day escitalopram, or 400 mg/day moxifloxacin (a positive control known to cause QTc prolongation). At 10 mg/day, escitalopram increased the QTc interval by 4.5 milliseconds (ms). At 30 mg/day, the QTc increased by 10.7 ms. [ 40 ] A QTc increase of less than 60 ms is not likely to confer significant risk. [ 39 ] The 30 mg/day escitalopram dose induced significantly less QTc prolongation than a therapeutically equivalent 60 mg/day dose of citalopram , which increased the QTc interval by 18.5 ms. [ 39 ]
More data about the cardiac risk from escitalopram can be found in a large observational study from Sweden that took note of all the medications used by all the patients presenting with TdP, and found the incidence of TdP in escitalopram users to be only 0.7 cases of TdP for every 100,000 patients who took the drug (ages 18-64), and only 4.1 cases of TdP for every 100,000 elderly patients who took the drug (ages 65 and up). [ 41 ] Of the 9 antidepressants that were used by patients with TdP, escitalopram ranked 7th by TdP incidence in elderly patients (only venlafaxine and amitriptyline had less risk), and it ranked 5th of 9 by TdP incidence in patients ages 18-64. Antidepressants as a class had a relatively low risk of TdP, and most patients on an antidepressant who experienced TdP were also taking another drug that prolonged QT interval. Specifically, 80% of the escitalopram users who experienced TdP were taking at least one other drug known to cause TdP. For comparison, the most popular antiarrhythmic drug in the study was sotalol with 52,750 users, and sotalol had a TdP incidence of 81.1 cases and 41.2 cases of TdP per 100,000 users in the ≥65 and 18-64-year-old demographics, respectively. [ 41 ]
Drugs that prolong the QT interval, such as escitalopram, should be used with caution in those with congenital long QT syndrome or known pre-existing QT interval prolongation, or in combination with other medicines that prolong the QT interval. ECG measurements should be considered for patients with cardiac disease , and electrolyte disturbances should be corrected before starting treatment. In December 2011, the UK implemented new restrictions on the maximum daily doses at 20 mg for adults and 10 mg for those older than 65 years or with liver impairment . [ 42 ] [ 43 ] The US Food and Drug Administration and Health Canada did not similarly order restrictions on escitalopram dosage, only on its predecessor citalopram . [ 44 ]
Like other SSRIs, escitalopram has also been reported to cause hyponatremia (low sodium levels), with rates ranging from 0.5 to 32%, which can often be attributed to SIADH . [ 45 ] This is typically not dose-dependent and at higher risk for occurrence within the first few weeks of starting treatment. [ 46 ]
Like other SSRIs, escitalopram often exacerbates symptoms of mania and hypomania in individuals misdiagnosed with a depressive disorder instead of a bipolar disorder , making it crucial for clinicians to rule out bipolar disorders before prescribing escitalopram. [ 15 ]
Very common effects (>10% incidence) include: [ 15 ] [ 47 ] [ 48 ] [ 4 ] [ 49 ]
Common effects (1–10% incidence) include:
The most common effect is fatigue or somnolence, particularly in older adults, [ 50 ] although patients with pre-existing daytime sleepiness and fatigue may experience paradoxical improvement of these symptoms. [ 51 ]
Escitalopram has not been shown to affect serial reaction time, logical reasoning, serial subtraction, multitasking, or Mackworth Clock task performance. [ 52 ]
Some people experience persistent sexual side effects when taking SSRIs or after discontinuing them. [ 53 ] Symptoms of medication-induced sexual dysfunction from antidepressants include difficulty with orgasm, erection, or ejaculation. [ 53 ] Other symptoms may be genital anesthesia, anhedonia , decreased libido, vaginal lubrication issues, and nipple insensitivity in women. Rates are unknown, and there is no established treatment. [ 54 ]
Antidepressant exposure (including escitalopram) is associated with shorter duration of pregnancy (by three days), increased risk of preterm delivery (by 55%), lower birth weight (by 75 g), and lower Apgar scores (by <0.4 points). Antidepressant exposure is not associated with an increased risk of spontaneous abortion. [ 55 ] There is a tentative association of SSRI use during pregnancy with heart problems in the baby. [ 56 ] The advantages of their use during pregnancy may thus not outweigh the possible negative effects on the baby. [ 56 ]
Escitalopram discontinuation, particularly abruptly, may cause certain withdrawal symptoms such as "electric shock" sensations, [ 57 ] colloquially called "brain shivers" or " brain zaps " by those affected. Frequent symptoms in one study were dizziness (44%), muscle tension (44%), chills (44%), confusion or trouble concentrating (40%), amnesia (28%), and crying (28%). Very slow tapering is recommended. [ 58 ] There have been spontaneous reports of discontinuation of escitalopram and other SSRIs and SNRIs, especially when abrupt, leading to dysphoric mood, irritability , agitation, anxiety, headache, lethargy , emotional lability , insomnia , and hypomania . Other symptoms such as panic attacks , hostility, aggression , impulsivity , akathisia (psychomotor restlessness), mania , worsening of depression, and suicidal ideation can emerge when the dose is adjusted down. [ 59 ]
Excessive doses of escitalopram usually cause relatively minor untoward effects, such as agitation and tachycardia . However, dyskinesia , hypertonia , and clonus may occur in some cases. Severe side effects of escitalopram overdose include seizures (which may be delayed), cardiovascular toxicity including QRS/QTc prolongation which can lead to arrhythmias ( Torsades de pointes , ventricular fibrillation, and ventricular tachycardia), hypertension, and serotonin syndrome. Treatment of escitalopram overdoses typically involves supportive care, such as giving Activated charcoal or giving benzodiazepines for seizures. [ 31 ] Because of the risk of arrhythmias (which may be delayed) prolonged cardiac monitoring is strongly recommended [ 31 ]
Escitalopram weakly inhibits CYP2D6 , and hence may increase plasma levels of some CYP2D6 substrates such as aripiprazole , risperidone , tramadol , codeine , etc. [ 6 ] As escitalopram is only a weak inhibitor of CYP2D6, analgesia from tramadol may not be affected. [ 60 ] Escitalopram (at the maximum dose of 20 mg/day) has been found to increase peak levels of the CYP2D6 substrate desipramine by 40% and total exposure by 100%. [ 7 ] Likewise, it has been found to increase peak levels of the CYP2D6 substrate metoprolol by 50% and overall exposure by 82%. [ 7 ] Escitalopram does not inhibit CYP3A4 , CYP1A2 , CYP2C9 , CYP2C19 , or CYP2E1 . [ 6 ] [ 7 ]
Exposure to escitalopram is increased moderately, by about 50%, when it is taken with omeprazole , a CYP2C19 inhibitor. [ 6 ] The authors of this study suggested that this increase is unlikely to be of clinical concern. [ 61 ] Combination of citalopram with fluoxetine or fluvoxamine resulted in increased exposure to the escitalopram enantiomer, owing to the strong inhibition of CYP2C19 and CYP2D6 by these agents. [ 7 ] Bupropion , a known strong CYP2D6 inhibitor, has been found to significantly increase citalopram plasma concentration and systemic exposure (peak levels increased by 30%, total exposure increased by 40%); as of April 2018 [update] the interaction with escitalopram had not been studied, but some monographs warned of the potential interaction. [ 62 ] Citalopram did not affect the pharmacokinetics of bupropion or its metabolites in the study. [ 62 ]
Escitalopram should be taken with caution when using St. John's wort , ginseng , dextromethorphan (DXM) , linezolid , tramadol, and other serotonergic drugs due to the risk of serotonin syndrome . [ 63 ] [ 64 ] As an SSRI, escitalopram should not be given concurrently with MAOIs . [ 65 ]
Escitalopram, similarly to other SSRIs, may increase bleeding risk with NSAIDs ( ibuprofen , naproxen , mefenamic acid ), antiplatelet drugs , anticoagulants , omega-3 fatty acids , vitamin E , and garlic supplements due to escitalopram's inhibitory effects on platelet aggregation via blocking serotonin transporters on platelets. [ 66 ]
Escitalopram can also prolong the QT interval, and hence it is not recommended in patients who are concurrently on other medications that also can prolong the QT interval. These drugs include antiarrhythmics , antipsychotics , tricyclic antidepressants , some antihistamines ( astemizole , mizolastine ), macrolide and fluoroquinolone antibiotics , some 5-HT 3 receptor antagonists (except palonosetron), and some antiretrovirals ( ritonavir , saquinavir , lopinavir ). [ 42 ]
Escitalopram increases intrasynaptic levels of the neurotransmitter serotonin by blocking the reuptake of the neurotransmitter into the presynaptic neuron. Over time, this leads to a downregulation of pre-synaptic 5-HT 1A receptors , which is associated with an improvement in passive stress tolerance, and delayed downstream increase in expression of brain-derived neurotrophic factor , which may contribute to a reduction in negative affective biases. [ 69 ] [ 70 ]
Of the SSRIs currently available, escitalopram has the highest selectivity for the serotonin transporter (SERT) compared to the norepinephrine transporter (NET), making the side-effect profile relatively mild in comparison to less-selective SSRIs. [ 65 ] In addition to its antagonist action at the orthosteric site of SERT, escitalopram also binds to an allosteric site on the transporter, thereby decreasing its disassociation rate. [ 71 ] Escitalopram binds to this allosteric site at a greater affinity than other SSRIs. [ 72 ] The clinical relevance of this action is unknown.
Escitalopram is a substrate of P-glycoprotein and hence P-glycoprotein inhibitors such as verapamil and quinidine may improve its blood-brain barrier penetrability. [ 73 ] In a preclinical study in rats combining escitalopram with a P-glycoprotein inhibitor, its antidepressant-like effects were enhanced. [ 73 ]
Escitalopram is the ( S )- enantiomer (left-handed version) of the racemate citalopram , which is responsible for its name: es citalopram. [ 8 ] [ 74 ]
Escitalopram was developed in cooperation between Lundbeck and Forest Laboratories . Its development was initiated in 1997, and the resulting new drug application was submitted to the US FDA in March 2001. The short time (3.5 years) it took to develop escitalopram can be attributed to the previous experience of Lundbeck and Forest with citalopram, which has similar pharmacology. [ 75 ]
Escitalopram is sold under many brand names worldwide such as Cipralex, Lexapro, Lexam, Mozarin, Aciprex, Depralin, Ecytara, Elicea, Gatosil, Nexpram, Nexito, Nescital, Szetalo, Stalopam, Pramatis, Betesda, Scippa and Rexipra. [ 1 ] [ 76 ]
The FDA issued the approval of escitalopram for major depression in August 2002, and for generalized anxiety disorder in December 2003. In May 2006, the FDA approved a generic version of escitalopram by Teva . [ 77 ] In July 2006, the U.S. District Court of Delaware decided in favor of Lundbeck regarding a patent infringement dispute and ruled the patent on escitalopram valid. [ 78 ]
In 2006, Forest Laboratories was granted an 828-day (2 years and 3 months) extension on its US patent for escitalopram. [ 79 ] This pushed the patent expiration date from 7 December 2009, to 14 September 2011. Together with the 6-month pediatric exclusivity, the final expiration date was 14 March 2012.
In 2004, separate civil suits alleging illegal marketing of citalopram and escitalopram for use by children and teenagers by Forest were initiated by two whistleblowers: a physician named Joseph Piacentile and a Forest salesman named Christopher Gobble. [ 80 ] In February 2009, the suits were joined. Eleven states and the District of Columbia filed notices of intent to intervene as plaintiffs in the action.
The suits alleged that Forest illegally engaged in off-label promotion of Lexapro for use in children; hid the results of a study showing lack of effectiveness in children; paid kickbacks to physicians to induce them to prescribe Lexapro to children; and conducted so-called "seeding studies" that were, in reality, marketing efforts to promote the drug's use by doctors. [ 81 ] [ 82 ] Forest denied the allegations [ 83 ] but ultimately agreed to settle with the plaintiffs for over $313 million. [ 84 ] | https://en.wikipedia.org/wiki/List_of_adverse_effects_of_escitalopram |
Adverse effects by frequency for use of valproate semisodium . [ 1 ] [ 2 ] [ 3 ] | https://en.wikipedia.org/wiki/List_of_adverse_effects_of_valproate_semisodium |
Aerospace (or aeronautical) engineering can be studied at the bachelors , masters and Ph.D. levels in aerospace engineering departments at many universities, and in mechanical engineering departments at others.
Institution names are followed by accreditation where applicable.
In Brazil the B.Sc., M.Sc. and PhD degrees in Aerospace Engineering are offered by universities like: Universidade Federal de Santa Catarina – UFSC at Joinville campus, Universidade Federal do ABC – UFABC at Sao Bernardo do Campo campus, Universidade de São Paulo – USP at São Carlos campus, Instituto Tecnologico de Aeronautica – ITA, Universidade Federal de Minas Gerais – UFMG and Universidade de Brasília - UnB at Gama campus. The admission for these courses features among the most difficult in Brazil, partly due to its competitive Vestibular (similar to ACT and SAT in USA).
In Canada, undergraduate degrees in aerospace (or aeronautical) engineering can be earned at Carleton University , Concordia University , École Polytechnique de Montréal , the Royal Military College of Canada and Toronto Metropolitan University . Undergraduate aerospace engineering options, or related programs, are available through, University of British Columbia , McGill University , the University of Toronto , the University of Windsor , and the University of Manitoba . The Canadian Engineering Accreditation Board is responsible for accrediting undergraduate aerospace engineering programs, [ 7 ] graduate study in aerospace engineering is also available at several Canadian post-secondary institutions, though Canadian post-graduate engineering programs do not require accreditation.
In Québec, École Polytechnique de Montréal , McGill University , Laval University , Université de Sherbrooke , Concordia University and École de Technologie Supérieure offer a joint program in the field of aeronautics and space technology leading to a M.Eng. (Aero).
Only undergraduate engineering programs in Canada are accredited, [ 7 ] and this is done by the Canadian Engineering Accreditation Board .
List of public universities and engineering schools:
List of private engineering schools:
Aerospace (or aeronautical) engineering can be studied at the bachelor's, master's, and Ph.D. levels in aerospace engineering departments at many Indian universities, and in mechanical engineering departments at others. A few departments offer degrees in space-focused astronautical engineering. Aerospace (or aeronautical) engineering in India has a history even before the Independence of India.
Aerospace Engineering is a relatively new profession in Pakistan. Its scope is currently high and expected to grow more in future. At present, many institutions offer degrees in Aerospace Engineering and related disciplines.
The Accreditation Board for Engineering and Technology (ABET) accredits two of the institutions offering aerospace (or aeronautical) engineering degrees in Turkey.
In the UK, aerospace (or aeronautical) engineering can be studied at the B.Eng. , M.Eng. , MSc. and Ph.D. levels at a number of universities. The first institution in the UK to teach in this field was Queen Mary, University of London , [ 171 ] which, with the dissolution of the University of Paris (whose chair was founded at around the same time [ 172 ] ), maintains the longest continuous experience of doing so in the world. In 2017, The Complete University Guide rankings for the top ten undergraduate programs in the United Kingdom were: (1) University of Cambridge , (2) Imperial College London , (3) University of Bristol , (4) University of Bath , (5) University of Southampton , (6) Loughborough University , (7) University of Surrey , (8) University of Leeds , (9) University of Nottingham , and (10) University of Glasgow , where parentheses indicate the ranking. [ 173 ] University of Cambridge and Imperial College London are consistently placed within the top 10 institutions offering undergraduate programs and research in aeronautical engineering, both being ranked within the top 10 in the world every year since 2013 by QS World University Rankings and Times Higher Education World University Rankings . [ 174 ] [ 175 ] The Department of Aeronautics at Imperial College London is noted for providing engineers for the Formula One industry, [ 176 ] an industry that uses aerospace technology . Cranfield University is also known to produce the largest number of postgraduates in the UK with an aerospace engineering related degree. [ 177 ]
Aerospace (or aeronautical) engineering can be studied at the advanced diploma , bachelor's , master's , and Ph.D. levels in aerospace engineering departments at many U.S. universities, and in mechanical engineering departments at others. A few departments offer degrees in space-focused astronautical engineering.
In 2015, the U.S. News & World Report rankings for the top ten undergraduate programs were: (1) Massachusetts Institute of Technology , (2) Georgia Institute of Technology , (3) University of Michigan , (4) Purdue University , (5) California Institute of Technology , (6) Stanford University , (7) Princeton University , (8) University of Illinois at Urbana–Champaign , (9) University of Maryland, College Park , and (10) University of Colorado at Boulder , [10] University of Texas, Austin , where parentheses indicate the ranking, and same number indicates a tie in scores. [ 178 ]
In 2016, the U.S. News & World Report rankings for the top ten graduate programs were: (1) Massachusetts Institute of Technology , (2) Georgia Institute of Technology , (2) Stanford University , (4) University of Michigan , (4) California Institute of Technology , (6) Purdue University , (7) University of Texas at Austin , (8) University of Illinois at Urbana–Champaign , (8) University of Colorado at Boulder , (10) Texas A&M University , (10) University of Maryland, College Park , where parenthesis indicate the ranking and the same number indicates a tie in scores. [ 179 ]
The Accreditation Board for Engineering and Technology (ABET) accredits almost all of the institutions offering aerospace (or aeronautical) engineering degrees in the United States. | https://en.wikipedia.org/wiki/List_of_aerospace_engineering_schools |
Flight test centers around the world all have similar missions: to conduct flight research and testing of new aircraft concepts and prototypes. Notable centers are listed below (by year of foundation): [ 1 ] [ 2 ] | https://en.wikipedia.org/wiki/List_of_aerospace_flight_test_centres |
Alchemical Studies produced a number of substances, which were later classified as particular Chemical Compounds or mixture of compounds.
Many of these terms were in common use into the 20th century. | https://en.wikipedia.org/wiki/List_of_alchemical_substances |
This is a list of algebraic coding theory topics. | https://en.wikipedia.org/wiki/List_of_algebraic_coding_theory_topics |
An algebraic construction is a method by which an algebraic entity is defined or derived from another.
Instances include: | https://en.wikipedia.org/wiki/List_of_algebraic_constructions |
This is a list of algebraic geometry topics , by Wikipedia page. | https://en.wikipedia.org/wiki/List_of_algebraic_geometry_topics |
This is a list of algebraic topology topics .
Example: DE-9IM | https://en.wikipedia.org/wiki/List_of_algebraic_topology_topics |
This list is ordered by the number of carbon atoms in an alcohol . | https://en.wikipedia.org/wiki/List_of_alkanols |
The following are among the principal radioactive materials known to emit alpha particles . | https://en.wikipedia.org/wiki/List_of_alpha_emitting_materials |
This is a list of software that provides an alternative graphical user interface for Microsoft Windows operating systems . The technical term for this interface is a shell . Windows' standard user interface is the Windows shell ; Windows 3.0 and Windows 3.1x have a different shell, called Program Manager . The programs in this list do not restyle the Windows shell, but replace it; therefore, they look and function differently, and have different configuration options. | https://en.wikipedia.org/wiki/List_of_alternative_shells_for_Windows |
This is a list of software for amateur radio .
The Debian project maintains a pure blend that includes ham radio software. [ 2 ] The HamBSD project is a variation of OpenBSD. [ 3 ]
This article related to amateur radio is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/List_of_amateur_radio_software |
When heated, ammonium nitrate decomposes non-explosively into nitrous oxide and water vapor ; however, it can be induced to decompose explosively by detonation into oxygen , nitrogen , and water vapor. Large stockpiles of the material can be a major fire risk due to their supporting oxidation , and may also detonate, as happened in the Texas City disaster of 1947 which led to major changes in the regulations for storage and handling.
There are two major classes of incidents resulting in explosions:
Ammonium nitrate decomposes in temperatures above 169 °C (336 °F). Pure AN is stable and will stop decomposing once the heat source is removed, but when catalysts are present, the reaction can become self-sustaining (known as self-sustaining decomposition, or SSD). This is a well-known hazard with some types of NPK fertilizers and is responsible for the loss of several cargo ships.
The column AN states the amount of ammonium nitrate consumed in the disaster in metric tonnes.
870 | https://en.wikipedia.org/wiki/List_of_ammonium_nitrate_incidents_and_disasters |
In anatomy, isthmus refers to a constriction between organs. This is a list of anatomical isthmi: | https://en.wikipedia.org/wiki/List_of_anatomical_isthmi |
This is a list of animals that have a naturally occurring hump or humps as a part of their anatomy.
Humps may evolve , as a store of fat, as a heat control mechanism, as a development of muscular strength, as a form of display to other animals, or be apparent as a consequence of some behaviour such as the diving of whales. Enlarged humps have also been selected for by some animal breeders for aesthetic or religious reasons. | https://en.wikipedia.org/wiki/List_of_animals_with_humps |
A list of groups who are anti-vaccine , vaccine-critical, or vaccine hesitant . | https://en.wikipedia.org/wiki/List_of_anti-vaccination_groups |
A list of antibiotic resistant bacteria is provided below. These bacteria have shown antibiotic resistance (or antimicrobial resistance ).
Clostridioides difficile is a nosocomial pathogen that causes diarrheal disease worldwide. [ 2 ] [ 3 ] Diarrhea caused by C. difficile can be life-threatening. Infections are most frequent in people who have had recent medical and/or antibiotic treatment. C. difficile infections commonly occur during hospitalization. [ 4 ]
According to a 2015 CDC report, C. difficile caused almost 500,000 infections in the United States per year. Associated with these infections were an estimated 15,000 deaths. The CDC estimates that C. difficile infection costs could amount to $3.8 billion over five years. [ 5 ]
C. difficile colitis is most strongly associated with fluoroquinolones , cephalosporins , carbapenems , and clindamycin . [ 6 ] [ 7 ] [ 8 ]
Some research suggests the overuse of antibiotics in the raising of livestock is contributing to outbreaks of bacterial infections such as C. difficile .[16]
Antibiotics, especially those with a broad activity spectrum (such as clindamycin) disrupt normal intestinal flora. This can lead to an overgrowth of C. difficile , which flourishes under these conditions. Pseudomembranous colitis can follow, creating generalized inflammation of the colon and the development of "pseudomembrane", a viscous collection of inflammatory cells, fibrin, and necrotic cells.[4] Clindamycin -resistant C. difficile was reported as the causative agent of large outbreaks of diarrheal disease in hospitals in New York, Arizona, Florida, and Massachusetts between 1989 and 1992. [ 9 ] Geographically dispersed outbreaks of C. difficile strains resistant to fluoroquinolone antibiotics, such as ciprofloxacin and levofloxacin, were also reported in North America in 2005. [ 10 ]
Multidrug-resistant Enterococcus faecalis and Enterococcus faecium are associated with nosocomial infections . [ 11 ] These strains include: penicillin -resistant Enterococcus , vancomycin-resistant Enterococcus , and linezolid -resistant Enterococcus . [ 12 ]
Tuberculosis (TB) resistant to antibiotics is called MDR TB (multidrug-resistant TB). Globally, MDR TB causes 150,000 deaths annually. [ 13 ] The rise of the HIV/AIDS epidemic has contributed to this. [ 14 ]
Mycobacterium tuberculosis is an obligate pathogen that has evolved to ensure its persistence in human populations. [ 15 ] This is evident in that Mycobacterium tuberculosis must cause a pulmonary disease in order to be successfully transmitted from one person to another. Tuberculosis better known as TB has one of the highest mortality rates among pathogens in the world. Mortality rates have not seen a significant decrease due to its growing resistance to certain antibiotics. [ 13 ] Although years of research have been devoted to the creation of a vaccine, one still does not exist. TB is extremely transmissible, contributing significantly to its very high level of virulence. TB was considered one of the most prevalent diseases, and did not have a cure until the discovery of streptomycin by Selman Waksman in 1943. [ 16 ] However, the bacteria soon developed resistance. Since then, drugs such as isoniazid and rifampin have been used. M. tuberculosis develops resistance to drugs by spontaneous mutations in its genomes. These types of mutations can lead to genotype and phenotype changes that can contribute to reproductive success, leading to the evolution of resistant bacteria. Resistance to one drug is common, and this is why treatment is usually done with more than one drug. Extensively drug-resistant TB (XDR TB) is TB that is also resistant to the second line of drugs. [ 14 ] [ 17 ]
Resistance of Mycobacterium tuberculosis to isoniazid , rifampin , and other common treatments has become an increasingly relevant clinical challenge. Evidence is lacking for whether these bacteria have plasmids. [ 18 ] M. tuberculosis lack the opportunity to interact with other bacteria in order to share plasmids. [ 18 ] [ 19 ]
Mycoplasma genitalium is a small pathogenic bacterium that lives on the ciliated epithelial cells of the urinary and genital tracts in humans. It is still controversial whether or not this bacterium is to be recognized as a sexually transmitted pathogen. Infection with Mycoplasma genitalium sometimes produces clinical symptoms, or a combination of symptoms, but sometimes can be asymptomatic. It causes inflammation in the urethra ( urethritis ) both in men and women, which is associated with mucopurulent discharge in the urinary tract, and burning while urinating. [ citation needed ]
Treatment of Mycoplasma genitalium infections is becoming increasingly difficult due to rapidly developing multi-drug resistance, and diagnosis and treatment is further hampered by the fact that M. genitalium infections are not routinely detected. [ 20 ] Azithromycin is the most common first-line treatment, but the commonly-used 1 gram single-dose azithromycin treatment can lead to the bacteria commonly developing resistance to azithromycin. [ 21 ] An alternative five-day treatment with azithromycin showed no development of antimicrobial resistance. [ 22 ] Efficacy of azithromycin against M. genitalium has decreased substantially, which is thought to occur through SNPs in the 23S rRNA gene. The same SNPs are thought to be responsible for resistance against josamycin , which is prescribed in some countries. [ 23 ] Moxifloxacin can be used as a second-line treatment in case azithromycin is not able to eradicate the infection. However, resistance against moxifloxacin has been observed since 2007, thought to be due to parC SNPs . [ 23 ] [ 24 ] Tetracyclines , including doxycycline , have a low clinical eradication rate for M. genitalium infections. [ 25 ] A few cases have been described where doxycycline, azithromycin and moxifloxacin had all failed, but pristinamycin was still able to eradicate the infection. [ 23 ]
Staphylococcus aureus is one of the major resistant pathogens. It caused more than 100,000 deaths attributed to AMR in 2019 and MRSA was present in 748,000 global deaths that year. [ 26 ] Found on the mucous membranes and the human skin of around a third of the population, it is extremely adaptable to antibiotic pressure. It was one of the earlier bacteria in which penicillin resistance was found, in 1947, just four years after mass-production began. Methicillin was then the antibiotic of choice, but has since been replaced by oxacillin because of significant kidney toxicity. Methicillin-resistant Staphylococcus aureus (MRSA) was first detected in Britain in 1961, and it is now "quite common" in hospitals [ citation needed ] . MRSA was responsible for 37% of fatal cases of sepsis in the UK in 1999, up from 4% in 1991. Half of all S. aureus infections in the US are resistant to penicillin, methicillin, tetracycline , and erythromycin . [ citation needed ]
Vancomycin non-susceptible isolates of Staph aureus have been isolated in Asia and the United States. [ 27 ] A study performed in 1992 demonstrated that Vancomycin resistance could be transferred from Enterococcus faecalis/faecium to Staph aureus through the transfer of the VanA and VanB genes. [ 28 ]
Streptococcus pyogenes (Group A Streptococcus : GAS) infections can usually be treated with many different antibiotics. Strains of S. pyogenes resistant to macrolide antibiotics have emerged; however, all strains remain uniformly susceptible to penicillin . [ 29 ]
Resistance of Streptococcus pneumoniae to penicillin and other beta-lactams is increasing worldwide. It was identified as one of six leading pathogens for disease associated with resistance in 2019 and that year there were 596,000 deaths globally of people with drug-resistant infection from the pathogen. [ 26 ] The major mechanism of resistance involves the introduction of mutations in genes encoding penicillin-binding proteins. Selective pressure is thought to play an important role, and use of beta-lactam antibiotics has been implicated as a risk factor for infection and colonization. S. pneumoniae is responsible for pneumonia , bacteremia , otitis media , meningitis , sinusitis , peritonitis and arthritis . [ 29 ]
Campylobacter causes diarrhea (often bloody), fever, and abdominal cramps. Serious complications such as temporary paralysis can also occur. Physicians rely on ciprofloxacin and azithromycin for treating patients with severe disease although Campylobacter is showing resistance to these antibiotics. [ 4 ]
Neisseria gonorrhoeae is a sexually transmitted pathogen that causes gonorrhea , a sexually transmitted disease that can result in discharge and inflammation at the urethra, cervix, pharynx, or rectum. [ 4 ] It can cause pelvic pain, pain on urination, penile and vaginal discharge, as well as systemic symptoms. It can also cause severe reproductive complications. [ 4 ]
As of 2013 hard-to-treat or untreatable infections of carbapenem-resistant Enterobacteriaceae (CRE), also known as carbapenemase-producing Enterobacteriaceae (CPE), were increasing among patients in medical facilities. CRE are resistant to nearly all available antibiotics. Almost half of hospital patients who get bloodstream CRE infections die from the infection. [ 4 ]
Klebsiella pneumoniae carbapenemase ( KPC )-producing bacteria are a group of emerging highly drug-resistant Gram-negative bacilli causing infections associated with significant morbidity and mortality whose incidence is rapidly increasing in a variety of clinical settings around the world. Klebsiella pneumoniae was identified as one of six leading pathogens for disease associated with resistance in 2019 and that year there were 642,000 deaths globally of people with drug-resistant infection from the pathogen. [ 26 ] Klebsiella pneumoniae includes numerous mechanisms for antibiotic resistance, many of which are located on highly mobile genetic elements. [ 30 ] Carbapenem antibiotics (heretofore often the treatment of last resort for resistant infections) are generally not effective against KPC-producing organisms. [ 31 ]
Infection with Escherichia coli and Salmonella can result from the consumption of contaminated food and polluted water . Both of these bacteria are well known for causing nosocomial (hospital-linked) infections, and often, these strains found in hospitals are antibiotic resistant because of adaptations to wide spread antibiotic use. [ 32 ] When both bacteria are spread, serious health conditions arise. Many people are hospitalized each year after becoming infected, with some dying as a result. Since 1993, some strains of E. coli have become resistant to multiple types of fluoroquinolone antibiotics . [ citation needed ] E. coli was identified as one of the six leading pathogens for deaths associated with resistance in 2019 and that year there were 829,000 deaths globally of people with drug-resistant infection from the pathogen. [ 26 ]
Although mutation alone plays a huge role in the development of antibiotic resistance, a 2008 study found that high survival rates after exposure to antibiotics could not be accounted for by mutation alone. [ 33 ] This study focused on the development of resistance in E. coli to three antibiotic drugs: ampicillin, tetracycline, and nalidixic acid. The researchers found that some antibiotic resistance in E. coli developed because of epigenetic inheritance rather than by direct inheritance of a mutated gene. This was further supported by data showing that reversion to antibiotic sensitivity was relatively common as well. This could only be explained by epigenetics. [ 33 ] Epigenetics is a type of inheritance in which gene expression is altered rather than the genetic code itself. There are many modes by which this alteration of gene expression can occur, including methylation of DNA and histone modification; however, the important point is that both inheritance of random mutations and epigenetic markers can result in the expression of antibiotic resistance genes. [ 33 ] Resistance to polymyxins first appear in 2011. [ 34 ] An easier way for this resistance to spread, a plasmid known as MCR-1 was discovered in 2015. [ 34 ]
Acinetobacter is a gram-negative bacteria that causes pneumonia or bloodstream infections in critically ill patients. Multidrug-resistant Acinetobacter have become very resistant to antibiotics. [ 4 ] Acinetobacter baumannii was identified as one of the six leading pathogens for deaths associated with resistance in 2019 and that year there were 423,000 deaths globally of people with drug-resistant infection from the pathogen. [ 26 ]
On November 5, 2004, the Centers for Disease Control and Prevention (CDC) reported an increasing number of Acinetobacter baumannii bloodstream infections in patients at military medical facilities in which service members injured in the Iraq / Kuwait region during Operation Iraqi Freedom and in Afghanistan during Operation Enduring Freedom were treated. Most of these showed multidrug resistance (MRAB), with a few isolates resistant to all drugs tested. [ 35 ] [ 36 ]
Pseudomonas aeruginosa is a highly prevalent opportunistic pathogen . It was identified as one of the six leading pathogens for deaths associated with resistance in 2019 and that year there were 334,000 deaths globally of people with drug-resistant infection from the pathogen. [ 26 ] One of the most worrisome characteristics of P. aeruginosa is its low antibiotic susceptibility, which is attributable to a concerted action of multidrug efflux pumps with chromosomally encoded antibiotic resistance genes (e.g., mexAB-oprM , mexXY ) and the low permeability of the bacterial cellular envelopes. [ 37 ] P. aeruginosa has the ability to produce 4-hydroxy-2-alkylquinolines (HAQs), and it has been found that HAQs have prooxidant effects and overexpressing modestly increased susceptibility to antibiotics. The study experimented with the P. aeruginosa biofilms and found that a disruption of relA and spoT genes produced an inactivation of the Stringent response (SR) in cells with nutrient limitation, which provides cells be more susceptible to antibiotics. [ 38 ] | https://en.wikipedia.org/wiki/List_of_antibiotic-resistant_bacteria |
This is a complete list of clinically approved prescription antidepressants throughout the world, as well as clinically approved prescription drugs used to augment antidepressants or mood stabilizers , by pharmacological and/or structural classification. Chemical/generic names are listed first, with brand names in parentheses. All drugs listed are approved specifically for major depressive disorder unless noted otherwise.
Selective serotonin reuptake inhibitors include:
Serotonin–norepinephrine reuptake inhibitors include:
Serotonin–dopamine reuptake inhibitors include:
None currently marketed
Serotonin–norepinephrine–dopamine reuptake inhibitors include:
Serotonin modulators and stimulators include:
Serotonin antagonist and reuptake inhibitors include:
Norepinephrine reuptake inhibitors include:
Norepinephrine–dopamine reuptake inhibitors include:
Tricyclic antidepressants include:
Opipramol (Insidon), tianeptine (Stablon, Coaxil) and amineptine (discontinued; formerly Survector, Maneon) are chemically TCAs but are pharmacodynamically atypical, and are therefore grouped elsewhere.
Tetracyclic antidepressants include:
Mianserin, mirtazapine, and setiptiline are also sometimes described as noradrenergic and specific serotonergic antidepressants (NaSSAs).
Monoamine oxidase inhibitors include
Discontinued/withdrawn
Discontinued/withdrawn
These drugs are sometimes described as reversible inhibitors of MAO-A (RIMAs).
Discontinued/withdrawn
Atypical antipsychotics include:
The following antidepressants are available both with a prescription and over-the-counter :
Atypical antipsychotics include:
Typical antipsychotics include:
None currently approved
Dopamine reuptake inhibitors include:
None currently approved | https://en.wikipedia.org/wiki/List_of_antidepressants |
Antimicrobial peptides are short peptides that possess antimicrobial properties. The female reproductive tract and its tissues produce antimicrobial peptides as part of the immune response . These peptides are able to fight pathogens and at the same time allow the maintenance of the microbiota that are part of the reproductive system in women . | https://en.wikipedia.org/wiki/List_of_antimicrobial_peptides_in_the_female_reproductive_tract |
This is a list of antioxidants naturally occurring in food. Vitamin C and vitamin E – which are ubiquitous among raw plant foods – are confirmed as dietary antioxidants, whereas vitamin A becomes an antioxidant following metabolism of provitamin A beta-carotene and cryptoxanthin . Most food compounds listed as antioxidants – such as polyphenols common in colorful, edible plants – have antioxidant activity only in vitro , as their fate in vivo is to be rapidly metabolized and excreted , and the in vivo properties of their metabolites remain poorly understood. For antioxidants added to food to preserve them, see butylated hydroxyanisole and butylated hydroxytoluene .
In the following discussion, the term "antioxidant" refers mainly to non-nutrient compounds in foods, such as polyphenols, which have antioxidant capacity in vitro and so provide an artificial index of antioxidant strength – the oxygen radical absorbance capacity (ORAC) measurement. Other than for dietary antioxidant vitamins – vitamin A , vitamin C and vitamin E – no food compounds have been proved to be antioxidants in vivo . Accordingly, regulatory agencies like the Food and Drug Administration of the United States and the European Food Safety Authority (EFSA) have published guidance disallowing food product labels to claim an inferred antioxidant benefit when no such physiological evidence exists. [ 1 ] [ 2 ]
Despite the above discussion implying that ORAC-rich foods with polyphenols may provide antioxidant benefits when in the diet, there remains no physiological evidence that any polyphenols have such actions or that ORAC has any relevance in the human body.
On the contrary, research indicates that although polyphenols are antioxidants in vitro , antioxidant effects in vivo are probably negligible or absent. [ 3 ] [ 4 ] [ 5 ] By non-antioxidant mechanisms still undefined, polyphenols may affect mechanisms of cardiovascular disease or cancer. [ 6 ]
The increase in antioxidant capacity of blood seen after the consumption of polyphenol-rich (ORAC-rich) foods is not caused directly by the polyphenols, but most likely results from increased uric acid levels derived from metabolism of flavonoids . [ 7 ] [ 8 ] According to Frei, "we can now follow the activity of flavonoids in the body, and one thing that is clear is that the body sees them as foreign compounds and is trying to get rid of them." [ 8 ] Another mechanism may be the increase in activities of paraoxonases by dietary antioxidants which can reduce oxidative stress . [ 9 ]
Natural phenols are a class of molecules found in abundance in plants. Many common foods contain rich sources of polyphenols which have antioxidant properties only in test tube studies. As interpreted by the Linus Pauling Institute , dietary polyphenols have little or no direct antioxidant food value following digestion. [ 7 ] Not like controlled test tube conditions, the fate of flavones or polyphenols in vivo shows they are poorly absorbed and poorly conserved (less than 5%), so that most of what is absorbed exists as metabolites modified during digestion, destined for rapid excretion. [ 8 ]
Spices, herbs, and essential oils are rich in polyphenols in the plant itself and shown with antioxidant potential in vitro . Red wine is high in total polyphenol count which supplies antioxidant quality which is unlikely to be conserved following digestion (see section below).
Deeply pigmented fruits like cranberries, blueberries, plums, blackberries, raspberries, strawberries, blackcurrants, and other fruits like figs, cherries, guava, oranges, mango, grape juice and pomegranate juice also have significant polyphenol content. [ 10 ]
Sorghum bran, cocoa powder, and cinnamon are rich sources of procyanidins, which are large molecular weight compounds found in many fruits and some vegetables. Partly due to the large molecular weight (size) of these compounds, their amount actually absorbed in the body is low, an effect also resulting from the action of stomach acids, enzymes, and bacteria in the gastrointestinal tract where smaller derivatives are metabolized and excreted. [ 7 ] [ 8 ]
Flavonoids , a subset of polyphenol antioxidants , are present in many berries , as well as in coffee and tea .
Examples:
Examples: | https://en.wikipedia.org/wiki/List_of_antioxidants_in_food |
Antiviral drugs are different from antibiotics. Flu antiviral drugs are different from antiviral drugs used to treat other infectious diseases such as COVID-19. Antiviral drugs prescribed to treat COVID-19 are not approved or authorized to treat flu. [ 1 ] | https://en.wikipedia.org/wiki/List_of_antiviral_drugs |
This list compares the features and functionality of application servers , grouped by the hosting environment that is offered by that particular application server.
(formerly BEA Systems )
(formerly JBoss AS)
(formerly JBoss )
Microsoft positions their middle-tier applications and services infrastructure in the Windows Server operating system and the .NET Framework technologies in the role of an application server:
Container based application servers run each application in a container. The application can be written in any programming language. | https://en.wikipedia.org/wiki/List_of_application_servers |
As of April 2011 [update] , several hundred trials of near-field communication have been conducted. Some firms have moved to full-scale service deployments, spanning either a single country or multiple countries.
Multi-country deployments include Orange 's roll-out of NFC technology to banks, retailers, transport, and service providers in multiple European countries, [ 1 ] and Airtel Africa and Oberthur Technologies deploying to 15 countries throughout Africa. [ 2 ] | https://en.wikipedia.org/wiki/List_of_applications_of_near-field_communication |
The Lua programming language is a lightweight multi-paradigm language designed primarily for embedded systems and clients.
This is a list of applications which use Lua for the purpose of extensibility.
In video game development , Lua is widely used as a scripting language by game programmers , perhaps due to its perceived easiness to embed, fast execution, and short learning curve . [ 1 ]
In 2003, a poll conducted by GameDev.net showed Lua as the most popular scripting language for game programming. [ 2 ] On 12 January 2012, Lua was announced as a winner of the Front Line Award 2011 from the magazine Game Developer in the category Programming Tools. [ 3 ]
Other applications using Lua include: | https://en.wikipedia.org/wiki/List_of_applications_using_Lua |
This is a list of aqueducts .
The unique Tokaanu Tailrace Bridge, a combined road and water bridge crosses a power canal of the Tongariro Power Scheme in the North Island of New Zealand . State Highway 41 travels along the top of this bridge, with the Tokaanu Stream, an important trout spawning stream, running under the road surface. | https://en.wikipedia.org/wiki/List_of_aqueducts |
This table lists the ionic species that are most likely to be present, depending on pH, in aqueous solutions of binary salts of metal ions. The existence must be inferred on the basis of indirect evidence provided by modelling with experimental data or by analogy with structures obtained by X-ray crystallography .
When a salt of a metal ion, with the generic formula MX n , is dissolved in water, it will dissociate into a cation and anions. [ citation needed ]
(aq) signifies that the ion is aquated, with cations having a chemical formula [M(H 2 O) p ] q+ and anions whose state of aquation is generally unknown. For convenience (aq) is not shown in the rest of this article as the number of water molecules that are attached to the ions is irrelevant in regard to hydrolysis. This reaction occurs quantitatively with salts of the alkali-metals at low to moderate concentrations. [ citation needed ]
With salts of divalent metal ions, the aqua-ion will be subject to a dissociation reaction, known as hydrolysis, a name derived from Greek words for water splitting. The first step in this process can be written as [ citation needed ]
When the pH of the solution is increased by adding an alkaline solution to it, the extent of hydrolysis increases. Measurements of pH or colour change are used to derive the equilibrium constant for the reaction. Further hydrolysis may occur, producing dimeric, trimeric or polymeric species containing hydroxy- or oxy- groups. The next step is to determine which model for the chemical processes best fits the experimental data. [ citation needed ]
The model is defined in terms of a list of those complex species which are present in solutions in significant amounts. In the present context the complex species have the general formula [M p O q (OH) r ] n± . where p, q and r define the stoichiometry of the species and n± gives the electrical charge of the ion. The experimental data are fitted to those models which may represent the species that are formed in solution. The model which gives the best fit is selected for publication. However, the pH range in which data may be collected is limited by the fact that an hydroxide with formula M(OH) n will be formed at relatively low pH, as illustrated at the right. This will make the process of model selection difficult when monomers and dimers are formed. and virtually impossible when higher polymers are also formed. In those cases it must be assumed that the species found in solids are also present in solutions.
The formation of an hydroxo-bridged species is enthalpically favoured over the monomers, countering the unfavourable entropic effect of aggregation. For this reason, it is difficult to establish models in which both types of species are present.
The extent of hydrolysis can be quantified when the values of the hydrolysis constants can be determined experimentally . The first hydrolysis constant refers to the equilibrium
The association constant for this reaction can be expressed as
Numerical values for this equilibrium constant can be found in papers concerned only with metal ion hydrolysis. However, it is more useful, in general, to use the acid dissociation constant , K a .
and to cite the cologarithm , pK a , of the value of this quantity in books and other publications. The two values are constrained by the relationship
pK w refers to the self-ionization of water : pK = log (1/K) = -log(K).
Further monomeric complexes may be formed in a stepwise manner.
Hydrolysed species containing two metal ions, with the general formula M 2 (OH) n , may be formed from pre-existing monomeric species. The stepwise reaction
illustrates the process. An alternative stepwise reaction
may also occur. Unfortunately it is not possible to distinguish between these two possibilities using data from potentiometric titrations because both of these reactions have no effect on the pH of the solution.
The concentration of a dimeric species decreases more rapidly with metal ion concentration than does the concentration of the corresponding monomeric species. Therefore, when determining the stability constants of both species it is usually necessary to obtain data from 2 or more titrations, each with a different metal salt concentration. Otherwise the stability constant non-linear least squares refinement may fail without providing the desired values, due to there being 100% mathematical correlation between the refinement parameters for the monomeric and dimeric species.
The principal problem when determining the stability constant for a polymeric species is how to select the "best" model to use from a number of possibilities. An example that illustrates the problem is shown in Baes & Mesmer, p. 119. [ 1 ]
A trimeric species must be formed from a chemical reaction of a dimer with a monomer, with the implication that the value of the stability constant of the dimer must be "known", having been determined using separate experimental data. In practice this extremely difficult to achieve. Instead, it is generally assumed that the species in solution are the same as the species that have been identified in crystal structure determinations. There is no way to establish whether or not the assumption is justified. Furthermore, species that are required as intermediaries between the monomer and the polymer may have such low concentrations as to be "undetectable".
An extreme example concerns the species with a cluster of 13 aluminium(III) ions, which can be isolated in the solid state; there must be at least 12 intermediate species in solution, which have not been characterized. It follows that the published stoichiometry of the polymeric species in solution may well be correct, but it is always possible that other species are actually present in solution. In general, the omission of intermediary species will affect the reliability of the published speciation schemes.
Some hydroxides of non-metallic elements are soluble in water; they are not included in the following table. Examples cited by Baes and Mesmer (p. 413) include hydroxides of Gallium (III), Indium (III), Thallium (III), Arsenic (III), Antimony (III) and Bismuth (III). Most hydroxides of transition metals are classified as being "insoluble" in water. Some of them dissolve, with reaction, in alkaline solution.
For some highly radioactive elements, such as astatine and radon, only trace quantities have been experimented on. As such, unambiguous characterisation of the species they form is impossible, and so their species have been excluded from the table below. Some theoretical speculations as to what they might be are present in the literature; more information can be found at the main articles of the elements involved.
The occurrence of the different kinds of ions of the elements is shown in this periodic table: [ dubious – discuss ]
Rather than the periodic table being the sum of its groups and periods [ 4 ] an examination of the image shows several patterns [ 5 ] Thus, there is a largely a left-to-right transition in metallic character seen in the red-orange-sand-yellow colours for the metals, and the turquoise, blue and violet colours for the nonmetals. The dashed line seen in the periods 1 to 4 corresponds to notions of a dividing line between metals and nonmetals . The mixed species in periods 5 and 6 shows how much trouble chemists can have in assessing where to continue the dividing line. [ 6 ] [ 7 ] [ 8 ] The separate dashed boundary around the Nb-Ta-W-Tc-Re-Os-Ir hexad is an exemplar for the reputation many transition metals have for nonmetallic chemistry. [ 9 ]
Ⓐ Hydrogen is shown as being a cation former but most of its chemistry, "can be explained in terms of its tendency to [eventually] acquire the electronic configuration of…helium", [ 11 ] thereby behaving predominately as a nonmetal.
Ⓑ Beryllium has an isodiagonal relationship with aluminium, in group 13, such a relationship also occurring between B and Si; and C and P.
Ⓒ Cation-only elements are shown as being limited to sixteen elements: all those in group 1, and the heavier actinides .
Ⓓ Rare earth metals are the group 3 metals scandium, yttrium, lutetium and the lanthanides; scandium is the only such metal shown as being capable of forming an oxyanion.
Ⓔ Radioactive elements, such as the actinides, are harder to study. The known species may not represent the whole of what is possible, and the identifications may sometimes be in doubt. Astatine , as another example, is highly radioactive, and determining its stable species is "clouded by the extremely low concentrations at which astatine experiments have been conducted, and the possibility of reactions with impurities, walls and filters, or radioactivity by-products, [ 12 ] and other unwanted nano-scale interactions. Equally, as Kirby noted, “since the trace chemistry of I sometimes differs significantly from its own macroscopic chemistry, analogies drawn between At and I are likely to be questionable, at best." [ 13 ]
Ⓕ The earlier actinides, up to uranium, show some superficial resemblance to their transition metal counterparts in groups 3 to 9. [ 14 ]
Ⓖ Most of the transition metals are known for their nonmetallic chemistry, and this is particularly seen in the image for periods 5 and 6, groups 5 to 9. They nevertheless have the relatively high electrical conductivity values characteristic of metals. [ 15 ]
Ⓗ The transition metals (or d-block metals) further show electrochemical character, in terms of their capacity to form positive or negative ions, that is in-between that of (i) the s and f-block metals; and (ii) the p-block elements. [ 16 ] [ a ]
Ⓘ The p-block shows a relatively distinct cutoff in periods 1 to 4 between elements commonly recognised as metals and nonmetals. Periods 5 and 6 include elements commonly recognised as metalloids by authors who recognise such a class or subclass ( antimony and tellurium ), and elements less commonly recognised as such ( polonium and astatine ). [ 19 ]
Ⓙ Stein, in 1987, [ 20 ] showed the metalloid elements as occupying a zone in the p-block composed of B, Si, Ge, As, Sb, Po, Te, At and Rn. In the periodic table image these elements are found on the right or upper side of the dashed line traversing the p-block.
Ⓚ Of 103 elements shown in the image, just ten form anions, all of these being in the p-block: arsenic; the five chalcogens: oxygen, sulfur, selenium, tellurium, polonium; and the four halogens: fluorine, chlorine, bromine, and iodine
Ⓛ Anion-only elements are confined to oxygen and fluorine . | https://en.wikipedia.org/wiki/List_of_aqueous_ions_by_element |
This article lists libraries, applications, and other software which enable or support arbitrary-precision arithmetic .
Software that supports arbitrary precision computations:
Programming languages that support arbitrary precision computations, either built-in, or in the standard library of the language:
For one-off calculations. Runs on server or in browser. No installation or compilation required. | https://en.wikipedia.org/wiki/List_of_arbitrary-precision_arithmetic_software |
Below is a list of notable companies that primarily focuses on artificial intelligence (AI). Companies that simply makes use of AI but have a different primary focus are not included. [ 1 ] [ 2 ] | https://en.wikipedia.org/wiki/List_of_artificial_intelligence_companies |
The Royal Society of Chemistry (RSC) owns a number of significant artworks in its venue at Burlington House in London. The collection is composed of busts, paintings and other artefacts that were mainly acquired between the mid-19th and early 21st centuries (the Chemical Society was founded in 1841 and merged with others to become the RSC in 1980). Most of the acquisitions were donations from past members and staff, although a few were purchased directly by the Society.
The bronze bust of Sir Humphry Davy was created by Ruby Levick and is a reproduction of an earlier sculpture by Miss Moore, donated to the Chemical Society by Rudolph Messell [ 1 ] [ 2 ] in 1900. At the Annual General Meeting of the Chemical Society of 29 March, Sir Thomas Edward Thorpe (President of the Society), reported on the gift of this work: [ 3 ] [ 4 ]
We are indebted to several of our Fellows for additions to the artistic possessions of the Society. Dr. Debus has presented us with a striking bust of Sir Humphry Davy, a cast of one modelled during his lifetime by Miss Moore. In accordance with the donor’s wishes, this bust now appears in our Meeting Room. On the recommendation of Mr. Thomas Armstrong , C.B., formerly the Art Director of the Science and Art Department, who was much impressed with the artistic quality of Miss Moore’s work, this bust has been copied by Miss Levick, with certain adaptations taken from Sir Thomas Lawrence ’s well-known portrait in the possession of the Royal Society , and has been reproduced in bronze. The reproduction, together with its pedestal, has been given by our colleague, Dr. Messel.
Sir Humphry Davy is best remembered today for his discoveries of several alkali and alkaline earth metals, as well as contributions to the discoveries of the elemental nature of chlorine and iodine.
Ruby Levick was a Welsh sculptor and medallist who had many of her works exhibited at the Royal Academy . [ 5 ] [ 6 ] [ 7 ] [ 8 ]
The bronze bust of John Dalton was also created by Ruby Levick and was donated to the Chemical Society in 1903 by its former President Sir Thomas Edward Thorpe, [ 4 ] as also attested by the inscription engraved on the bust's base: "John Dalton presented by T.E. Thorpe CB. L.L.D. F.R.S. past President in commemoration of the centenary of the enunciation of the atomic theory".
A copy of his accompanying letter was printed in the Proceedings of the Chemical Society in 1903 and read out by President William A. Tilden : [ 9 ]
The bronze is the work of Miss Levick, who is already favourably known to the Society by her reproduction of the bust of Davy in their possession. Of the artistic merits of her present work others must be the judge, but I may be permitted here to express my indebtedness to her for the skill and conscientious care with which she has striven to make a faithful and adequate presentment of the grand old philosopher.
John Dalton was an English chemist best known for his development of atomic theory .
A bronze bust representing Michael Faraday , English scientist whose studies greatly contributed to the fields of electromagnetism and electrochemistry . The bust was presented to the Chemical Society by James Emerson Reynolds (1844–1920), president of the Chemical Society from 1901 to 1903: [ 10 ] [ 11 ] [ 12 ]
Thursday, November 19th, 1908, at 8.30 p.m., Sir William Ramsay , K.C.B., F.R.S., President, in the Chair. The President announced that the Society had become indebted to J. Emerson Reynolds, F.R.S., for presenting a bust of Michael Faraday.
The marble bust representing Sir William Henry Perkin was presented to the Chemical Society in 1907 by a committee administering the fund subscribed in support of the international celebration for the fiftieth anniversary of the foundation of the Coal Tar Colour Industry. At the Annual General Meeting of the Society, President Raphael Meldola reported on this gift: [ 4 ] : 31
On the occasion of the International Celebration marking the Fiftieth Anniversary of the Foundation of the Coal Tar Colour Industry, an address of congratulation to Sir William Henry Perkin, F.R.S., was presented on behalf of the Society by the President. In accordance with the resolution of the public meeting at which the commemoration was inaugurated, a marble bust of Sir William Perkin, executed by Mr. F. W. Pomeroy, A.K.A., has been presented to the Society by the Committee administering the Fund subscribed in support of the celebration. [ 13 ]
Perkin's fame is mainly related to his discovery of mauveine .
The artist, Frederick William Pomeroy , was a British sculptor mainly prolific in ideal work and portrait busts, but also creator of public monuments. [ 8 ] [ 14 ]
The marble bust representing Sir Henry Enfield Roscoe by Alfred Drury was donated to the Chemical Society Library on 20 November 1913, on the occasion of Roscoe's eightieth birthday by his friends and pupils, [ 4 ] : 31 as also attested by the inscription on its base:
Roscoe 1913 presented by his pupils
.
In 1914 Professor William Perkin Jr. , president of the society, reported on the gift of this artefact:
It is with very great pleasure that the Council have to report that a bust of the Right Honourable Sir Henry Enfield Roscoe, by Mr. Alfred Drury, R.A., has been presented to the Society by the friends and former students of Sir Henry Roscoe. The presentation was made before a distinguished company in the Rooms of the Society on November 20th, and the bust now adorns the Library. [ 15 ]
President of the Chemical Society between 1880 and 1882, Roscoe was student as well as friend of the German chemist Robert Bunsen : in their researches laid the foundation of comparative photochemistry .
English architectural sculptor, Drury was elected Academician of the Royal Academy of Arts in 1913. He studied at the Oxford National Art Training School and in Paris. [ 8 ]
The bronze bust representing Baron Justus von Liebig was presented to the Chemical Society by Rudolph Messel [ 1 ] in 1903:
The bust of Liebig which was placed on the table is a gift which the Society owes to the generosity of our Fellow, Dr. Messel. [ 16 ]
as also confirmed by the inscription on the column supporting the bust:
Justus von Liebig presented to the Chemical Society by Rudolph Messel Phd May 1903.
Another inscription, placed between the back and the right side of the bust itself, provides information about its origin:
Munchen 1873. M. Wagmuller.
The artefact was created in Munich in 1873 by Michael Wagmüller , a German sculptor who completed a number of commissions in London and exhibited at the Royal Academy . [ 17 ]
Von Liebig is considered to have greatly contributed to the fields of agricultural and biological chemistry. He developed a manufacturing process for beef extracts and founded a company which later became Oxo . [ 18 ] He is also credited as the inventor of Marmite . [ 19 ]
The marble bust representing the German chemist August Wilhelm von Hofmann was introduced to the Chemical Society in 1876 by Mr James Duncan: [ 20 ]
In recording the gratitude of the Society to those Gentlemen, the name of another Fellow, Mr. James Duncan, must be included among the recipients of our thanks, for his gift of a very interesting and valuable bust of one of our most highly-esteemed Fellows and Past Presidents, Professor Hofmann, the presentation of which, so soon after the Society had the pleasure of welcoming Dr. Hofmann as Faraday Lecturer, has been peculiarly appropriate. It is to be hoped that this handsome gift of Mr. Duncan’s and the excellent photograph of the late Dr. Anderson, presented by his widow, will not long remain the only monumental records of this kind possessed by the Society, of eminent workers in chemical science, past and living.
The inscription at the back
Joh. Pfuhl fec. Berlin 1875
certifies that this artwork was created by the German sculptor Johannes Pfuhl in Berlin in 1875.
Justus von Liebig's pupil and William Perkin's mentor, von Hofmann widely contributed to the development of the organic chemistry. He was a cofounder of the German Chemical Society [ 21 ] and president of the Chemical Society between 1861 and 1863. [ 22 ]
A bronze bust of Jean Baptiste André Dumas , the French chemist best known for his works on organic analysis and synthesis, as well as the determination of atomic weights and molecular weights by measuring vapour densities.
The sculpture was presented to the Chemical Society in 1885 by Warren De la Rue : [ 23 ]
We have to thank one of our Past Presidents, Dr. De la Rue, who has always shown himself so ready to do anything that will add to the interest of the Society, for the bronze bust of the late Professor Dumas, which has now been placed in the library. It is contemplated placing this, and also that of Professor Hofmann, in more suitable positions than they now occupy.
An inscription on the right side of the bust provides us further information:
Eug Cvillavme 1883.
The work was created in 1883 by Jean-Baptiste Claude Eugène Guillaume , a French sculptor elected honorary member of the Royal Academy in 1869.
A bust of Robert Boyle , often regarded today as the first modern chemist.
Acquired by the Royal Society of Chemistry in 2003 from the Chelminski Gallery, this veined white marble bust was originally commissioned in 1731 from the Italian sculptor Giovanni Battista Guelfi (1690–1736) [ 24 ] by Lord Burlington , a relative of Boyle's, for Burlington House, which was then the earl's residence in London. [ 25 ] This work, originally displayed at Lord Burlington's Palladian villa, Chiswick House , is virtually identical to that commissioned by Queen Caroline for her grotto at Richmond in 1732–3. [ 26 ] [ 27 ] [ 28 ] The latter survives in the Royal Collection at Kensington Palace and has long been well-known. However, this other version of Guelfi's bust had hitherto been entirely unknown to Boyle scholars. [ 29 ]
Guelfi was an Italian sculptor who trained with Camillo Rusconi in Rome and was invited by Lord Burlington, in 1714, to move to England, where he restored the Arundel marbles and executed several portrait busts and monuments. [ 24 ]
This artefact was created in the 18th century. Made of gunmetal raised on a cross-banded walnut and oak base (32 cm × 44 cm. × 25.5 cm), it bears a presentation plaque with the following inscription:
This airpump was made for Dr Priestley by Mr Harrison the employer of Sir Josiah Mason when a young man. Presented by Josiah Martin Smith ESQ.
Samuel Harrison (1759–1833) was a split ring maker with a workshop in Lancaster Street, Birmingham. He was a member of Priestley's congregation at the New Meeting and is known to have assisted Priestley with his experiments. [ 30 ]
Raised on an oak plinth is a plaster, full-length figure of Joseph Priestley holding in his hands mortar and pestle, signed and inscribed "Esher" and dated 1874. Another inscription confirms that the statue was presented in 1920 by Mrs Bedford McNeill, as stated in the Journal and Proceedings of the Institute of Chemists of Great Britain and Ireland of that year: [ 31 ]
I am pleased, however, to call your attention to a bronzed cast of the figure of Priestley, a replica of the well-known statue by Williamson (the father of one of our Fellows). This has been received from Mrs. Bedford McNeill, whose husband was a Priestley Scholar, a Fellow and Member of Council. We are glad to have it in memory of an esteemed colleague and also because you will recognise that the design is the main feature of the Seal of the Institute.
The full size version of this sculpture by Francis John Williamson is located in Birmingham . It was originally made in marble, then re-cast in bronze and it portrays Dr Priestley absorbed in an experiment which led to his discovery of oxygen. [ 32 ]
This painting (oil on canvas, 127 cm × 158 cm), was bought from the Albemarle Gallery by the Royal Society of Chemistry in 2008. It is part of Stuart Luke Gatherer 's Sins and Virtues collection, which illustrates the seven sins and seven virtues using modern-day professions. [ 33 ] It is based on an earlier classic, An Experiment on a Bird in the Air Pump (1768) by Joseph Wright , which was in turn inspired by Robert Boyle's experiment on the properties of air in the mid-17th century: [ 4 ] : 32 a bird is deprived of air before a diversified audience and the different reactions of the spectators prove that scientific curiosity overcomes the concern for the living creature.
Stuart Luke Gatherer was brought up in the Eastern Highlands of Scotland, he graduated from Edinburgh College of Art in 1995 and exhibited across Scotland, in New York and in London. [ 34 ]
A painting (oil on canvas, 20 cm × 24 cm) by Christine Payne represents the well-known thought experiment Schrödinger's cat . An introductory note provides further information: [ 4 ] : 33
These small oil paintings which reference Schrodinger's hypothetical experiment consider the banality of representation and the representation of banality. They lie in the territory of the absurd, the paradoxical, the contradictory... and attempt to explore the space betwixt and between: the point of intervention: the moment of metamorphosis: the state of suspension within the nature of reality. For as in Schrodinger's experiment everything remains in limbo until an intelligent observer looks...
The original series consisted of nine paintings and two of them were shown in the exhibition 'Seeing Red' at the Science Museum from November 2001 to October 2002. The venue also purchased one of the paintings for their collection. [ 35 ]
A large (21.5 cm × 18.5 cm) Wedgwood Jasperware oval portrait plaque of Dr Joseph Priestley , attributed to William Hackwood ( c. 1779 ). [ 36 ]
The ebonized frame is inscribed
Priestley, presented by J.F. Thorpe
English theologian, philosopher and chemist, Joseph Priestley is credited with the discovery of oxygen. [ 37 ]
William Hackwood worked as prolific modeller for Josiah Wedgwood's factory between 1769 and 1832. [ 38 ]
A Wedgwood Jasperware oval portrait plaque (23 cm × 19 cm). Representing Robert Boyle, the artefacts bears, on its gilt-beaded ebonised frame, the following inscription: [ 36 ]
Presented in 1975 to commemorate his 50 years of fellowship of the Chemical Society by Dr. C. H. Spiers, a former pupil of Jocelyn Field Thorpe.
Robert Boyle's The Sceptical Chymist is considered a foundation in the chemistry field. He is best known for the Boyle's law , which describes the inversely proportional relationship between the absolute pressure and volume of a gas, if the temperature is kept constant within a closed system . [ 39 ]
Wedgwood is a fine china, porcelain and luxury accessories company founded in 1759 by Josiah Wedgwood . [ 40 ]
A head and shoulder portrait (oil on canvas, 61 cm × 49 cm) of Benjamin Collins Brodie , president of the Chemical Society between 1859 and 1861, chiefly known for his investigations on the allotropic states of carbon and for his discovery of graphitic acid. [ 41 ]
The plate on the frame is so inscribed:
Sir Benjamin Brodie, Bart, F.R.S. President 1859–1861. Presented to the Society by the Misses P.M. and O.M. Brodie
The painting is initialled and dated: [ 36 ] : 40
E.A. 1874
.
A three-quarter length portrait (oil on canvas, 108 cm × 85 cm) of Baron Justus Von Liebig seated, which is signed and dated 1860. [ 36 ] : 39
Created by the German artist Wilhelm Trautschold , [ 42 ] this artefact was, as its plate reads:
presented to the Chemical Society in October 1926 by Mrs Alec Tweedie , Nee Harley, god-daughter of Liebig. It was to save the life of her mother, Emma Muspratt, that Liebig prepared an extract of meat.
Margaret Trautschold Hayford says Trautschold painted four portraits of Liebig, who was a close friend and a colleague of his father in law: this one is listed in the checklist of Trautschold's work as no. 34, oil 40" x 30", signed and dated 1860 (and as being in the Chemical Society of London). [ 43 ] He was mainly active between 1849 and 1873 in Edinburgh, Liverpool and London. [ 44 ]
The portrait of Thomas Graham was specially commissioned by the Chemical Society in 1931. [ 4 ] : 32 Incoming President Professor George Henderson acknowledged this at the Annual General Meeting that year: [ 45 ]
At the invitation of the President, Professor Thorpe , on behalf of some 20 subscribers, asked Dr. M. A. Whiteley to unveil a portrait in oils of Thomas Graham, the first President of the Society. The portrait had been painted by Mr. H. A. Budd, R.O.I., from a lithograph by W. Bosley made from a daguerreotype by Chudet. The President, in accepting the portrait for the Society, expressed the thanks of the Fellows to Professor Thorpe and all the subscribers for their generosity.
The artist, Herbert Ashwin Budd , was born in 1881 in Staffordshire and died in 1950. He designed posters for London Transport in 1930s. London based artist and teacher, he painted portraits, landscapes and townscapes in oils. In 1907 he became an associate of the Royal College of Art and began to exhibit widely in the UK, at the New English Art Club and regularly at the Royal Academy . In 1921 he became a member of the Royal Institute of Oil Painters and in 1927 was awarded an Honourable Mention at the Paris Salon . From 1929 to 1949 he taught at St Martin's School of Art . [ 8 ] [ 46 ] [ 47 ]
Thomas Graham was the first president of the Chemical Society, in 1841. His main contributions to science were the studies on the diffusion of gases, resulted in Graham's law and the discovery of the medical method known as dialysis . [ 48 ]
A half-length portrait of Robert Boyle (oil on canvas 92 cm × 78.5 cm). [ 36 ] The Journal and Proceedings of the Institute of Chemistry of Great Britain and Ireland said about the work: [ 49 ]
The portrait of the Honourable Robert Boyle, in the Library of the Institute, is attributed to Jonathan Richardson , who left many portraits unsigned; this has been pronounced by several authorities as undoubtedly his work. The portrait bears the dates of Boyle’s birth and death (1626–1691) and was probably a posthumous portrait. Richardson was born in 1665; however, names and dates were often added to portraits long after they had been painted. The portrait resembles the engraving of a bust by Faber and bears a close likeness to Boyle’s sister, the Countess of Ranelagh, at whose house in London he lived and worked for many years. It has been objected that few of the nobility and gentlemen of the time of Charles I and James I were painted otherwise than in court dress. Portraits showing gentlemen in dressing gowns and velvet caps appeared more frequently about 1720, when Boyle had been dead nearly 30 years; but it may be suggested that Richardson preferred to represent him as a philosopher in his study. Towards the end of his life, Boyle lived very quietly in the country and did not frequent the court. The picture was purchased at a sale at Loudoun Castle , Galston, Ayrshire, and acquired for the Institute, by private subscription, in 1931.
The frame bears a plate with the inscription:
Robert Boyle 1627–1691 by the Studio of Johannes Kerseboom
and the painting itself is inscribed:
OB 1691: AET 65.
A three-quarter length portrait of Thomas Thomson seated at his desk (oil on board, 47 cm × 36 cm, carved giltwood frame). Attributed to the Scottish artist John Graham Gilbert , [ 36 ] it was presented by Dr John Naish Goldsmith, as reported by the inscription on the frame:
Thomas Thomson, M.D., F.R.S. (1773–1852) Vice President 1844–1846, presented by Dr J. N. Goldsmith.
Painter and art collector, John Graham-Gilbert exhibited most of his works between the Royal Academy in London and the Royal Scottish Academy in Edinburgh . [ 44 ]
Thomson was a Scottish chemist and mineralogist who invented a saccharometer for assessing sugar content of the fermenting must. [ 50 ] He accorded an effective support to Dalton's atomic theory . [ 51 ]
A three-quarter length profile portrait of Sir James Dewar (oil on canvas, 126 cm × 101 cm). The plate on the frame is so inscribed:
Sir James Dewar. President 1897–1899. Presented by Mrs. de l'Hopital, November, 1930.
The painting is signed and dated 1923: [ 36 ] the creator was the French artist René le Brun, Comte de L'Hôpital , [ 52 ] who studied at the Royal Academy in London. [ 8 ]
Scottish chemist and physicist, James Dewar is probably best known as the inventor of the Dewar flask . [ 53 ]
This painting (oil on canvas, 133 cm × 103 cm) depicts Sir Cyril Norman Hinshelwood seated at his desk, three-quarter length, dressed in red academic robes. The plate's frame states:
Sir Cyril Hinshelwood 1897–1967. Nobel Prizewinner for Chemistry, 1956.
Hinshelwood was an English physical chemist who gained many awards and honorary degrees. He was President of several English societies, such as the Chemical Society, the Faraday Society and the Royal Society . [ 54 ]
The portrait is attributed to Gerald Festus Kelly , [ 36 ] an artist born in London and educated at Cambridge University . During his life, Kelly visited many countries and exhibited more than 300 of his works at the Royal Academy, of which he was also President between 1949 and 1954. [ 44 ] [ 55 ]
The Proceedings of the Institute of Chemistry of Great Britain and Ireland said of this painting: [ 56 ]
The portrait of Prof. Meldola, referred to in the Report of the Council, was unveiled by Sir James Dobbie , President of the Institute, at a Special Meeting of the Council held on December 15th, 1917. Mrs. Meldola, Lady Dobbk, Prof. and Mrs. Poulton, and a number of friends and past students of Prof. Meldola were also present. The President said that Sir George Keilby had on the same afternoon unveiled another portrait of Prof. Meldola, by the same artist (Solomon J. Solomon), at the Royal Society. He referred to the late Professor’s interest in science generally as well as in that which he had chosen as his profession. It was fitting that such a memorial should find a place in the Council Room, especially in view of the valuable services rendered to the Institute by Prof. Meldola in connection with the new building during the last few years of his life. After alluding to the extraordinary range and varied character of Prof. Meldola’s activities in teaching, in research and in public affairs, he paid a tribute to his personal qualities as a man, remarking on his strong character and influence, his appreciation of humour, his fine literary gift and powers of conversation. Having unveiled the portrait the President warmly praised the work. All would agree that the artist had achieved a remarkable success. He also expressed the hearty thanks of the Institute to those who had subscribed to the presentation, and to Prof. Poulton for having been the means whereby the Institute had become possessed of such a valuable memorial to its past President. Prof. Poulton having replied, Mr. Gordon Salamon, Hon. Treasurer, also spoke in appreciation of the gift, and the President’s remarks were warmly endorsed by Mr. A. J. Chapman, a former student of Prof. Meldola.
Member of the Royal Academy, Solomon Joseph Solomon was a British artist who produced works of different style and different subjects, being very productive as innovative portraitist. [ 44 ] [ 57 ]
Raphael Meldola , British chemist and entomologist, was president of the Chemical Society between 1905 and 1907. [ 58 ]
This painting shows Michael Faraday giving one of a course of six Christmas Lectures at the Royal Institution . Focused on the distinctive properties of common metals, these lectures were delivered between 27 December 1855 and 8 January 1856. [ 59 ] Prince Albert , the Prince Consort ( Queen Victoria 's husband), and the Prince of Wales (later King Edward VII ) are in the front row.
The painting was purchased by the Faraday Society from the private museum of the Nowel ffarington family of Worden Hall in 1949. The plate on the frame gives the artist's name, Alexander Blaikley (1816–1903). [ 60 ] Born in Glasgow, Blaikley studied at the Trustees' Academy and at the Royal Academy, where he then exhibited most of his works. [ 44 ] | https://en.wikipedia.org/wiki/List_of_artworks_in_the_collection_of_the_Royal_Society_of_Chemistry |
Programs capable of Astrometric solving :
The solvers Elbrus and Charon are obsolete and no longer developed. | https://en.wikipedia.org/wiki/List_of_astrometric_solvers |
The following is a list of astronomers , astrophysicists and other notable people who have made contributions to the field of astronomy . They may have won major prizes or awards, developed or invented widely used techniques or technologies within astronomy, or are directors of major observatories or heads of space-based telescope projects.
Aaronson was one of the first astronomers to attempt to image dark matter using infrared imaging. He imaged infrared halos of unknown matter around galaxies that could be dark matter.
The following is a list of people who are not astronomers but made a contribution to the field of astronomy and astrophysics. | https://en.wikipedia.org/wiki/List_of_astronomers |
The following is a list of astronomical instrument makers , along with lifespan and country of work, if available. | https://en.wikipedia.org/wiki/List_of_astronomical_instrument_makers |
An astronomical instrument is a device for observing, measuring or recording astronomical data . They are used in the scientific field of astronomy , a natural science that studies celestial objects and the phenomena that occur in the cosmos, with the object of explaining their origin and evolution over time. Many are also used in navigation and surveying.
Astronomical instruments include: [ 1 ] | https://en.wikipedia.org/wiki/List_of_astronomical_instruments |
This is a partial list of astronomical observatories ordered by name, along with initial dates of operation (where an accurate date is available) and location. The list also includes a final year of operation for many observatories that are no longer in operation. While other sciences, such as volcanology and meteorology , also use facilities called observatories for research and observations, this list is limited to observatories that are used to observe celestial objects.
Astronomical observatories are mainly divided into four categories: space-based, airborne, ground-based, and underground-based.
Many modern telescopes and observatories are located in space to observe astronomical objects in wavelengths of the electromagnetic spectrum that cannot penetrate the Earth's atmosphere (such as ultraviolet radiation, X-rays , and gamma rays ) and are thus impossible to observe using ground-based telescopes. [ 1 ] Being above the atmosphere, these space observatories can also avoid the effects of atmospheric turbulence that plague ground based telescopes, although new generations of adaptive optics telescopes have since then dramatically improved the situation on the ground. The space high vacuum environment also frees the detectors from the ancestral diurnal cycle due to the atmospheric blue light background of the sky, thereby increasing significantly the observation time.
An intermediate variant is the airborne observatory , specialised in the infrared wavelengths of the electromagnetic spectrum, that conduct observations above the part of the atmosphere containing water vapor that absorbs them, in the stratosphere .
Historically, astronomical observatories consisted generally in a building or group of buildings where observations of astronomical objects such as sunspots , planets , asteroids , comets , stars , nebulae , and galaxies in the visible wavelengths of the electromagnetic spectrum were conducted. At first, for millennia, astronomical observations have been made with naked eyes. Then with the discovery of optics , with the help of different types of refractor telescopes and later with reflector telescopes . Their use allowed to dramatically increase both the collecting power and limit of resolution , thus the brightness , level of detail and apparent angular size of distant celestial objects allowing them to be better studied and understood. Following the development of modern physics , new ground-based facilities have been constructed to conduct research in the radio and microwave wavelengths of the electromagnetic spectrum, with radio telescopes and dedicated microwave telescopes .
Modern astrophysics has extended the field of study of celestial bodies to non-electromagnetic vectors, such as neutrinos , neutrons and cosmic rays or gravitational waves . Thus, new types of observatories have been developed. Interferometers are at the core of gravitational wave detectors. In order to limit the natural or artificial background noise , most particle detector based observatories are built deep underground . | https://en.wikipedia.org/wiki/List_of_astronomical_observatories |
This is a list of astronomical observatories in Ukraine : | https://en.wikipedia.org/wiki/List_of_astronomical_observatories_in_Ukraine |
A list of notable groups devoted to promoting astronomy research and education. | https://en.wikipedia.org/wiki/List_of_astronomical_societies |
This is a compilation of initialisms and acronyms commonly used in astronomy. Most are drawn from professional astronomy, and are used quite frequently in scientific publications. A few are frequently used by the general public or by amateur astronomers .
The acronyms listed below were placed into one or more of these categories: | https://en.wikipedia.org/wiki/List_of_astronomy_acronyms |
This list of astronomy awards is an index to articles about notable awards for contributions to astronomy . The list is organized by region and country of the sponsoring organization, but awards are not necessarily limited to people from that country. | https://en.wikipedia.org/wiki/List_of_astronomy_awards |
This is a list of scientific journals publishing articles in astronomy , astrophysics , and space sciences . | https://en.wikipedia.org/wiki/List_of_astronomy_journals |
An audio conversion app (also known as an audio converter ) transcodes one audio file format into another; for example, from FLAC into MP3 . It may allow selection of encoding parameters for each of the output file to optimize its quality and size. An audio converter uses at least two sets of audio codecs to decode the source file format and to encode the destination file.
Audio converters include: | https://en.wikipedia.org/wiki/List_of_audio_conversion_software |
This is a list of communication protocols used for the automation of processes (industrial or otherwise), such as for building automation , power-system automation , automatic meter reading , and vehicular automation . | https://en.wikipedia.org/wiki/List_of_automation_protocols |
The following is a list of awards in the fields of bioinformatics and computational biology . | https://en.wikipedia.org/wiki/List_of_awards_in_bioinformatics_and_computational_biology |
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