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54,405,493 | https://en.wikipedia.org/wiki/Digital%20phenotyping | Digital phenotyping is a multidisciplinary field of science, first defined in a May 2016 paper in JMIR Mental Health authored by John Torous, Mathew V Kiang, Jeanette Lorme, and Jukka-Pekka Onnela as the "moment-by-moment quantification of the individual-level human phenotype in situ using data from personal digital devices." The data can be divided into two subgroups, called active data and passive data, where the former refers to data that requires active input from the users to be generated, whereas passive data, such as sensor data and phone usage patterns, are collected without requiring any active participation from the user.
Smartphones are well suited for digital phenotyping given their widespread adoption and ownership, the extent to which users engage with the devices, and richness of data that may be collected from them. Smartphone data can be used to study behavioral patterns, social interactions, physical mobility, gross motor activity, and speech production, among others. Smartphone ownership has been in steady rise globally over the past few years. For example, in the U.S., smartphone ownership among adults increased from 35% in 2011 to 64% in 2015, and in 2017 an estimated 95% of Americans own a cellphone of some kind and 77% own a smartphone.
The use of passive data collection from smartphone devices can provide granular information relevant to psychiatric, aging, frailty, and other illness phenotypes. Types of relevant passive data include GPS data to monitor spatial location, accelerometer data to record movement and gross motor activity, and call and messaging logs to document social engagement with others. Passively collected data may also support clinical differentiation between diagnostic groups and monitoring mental health symptoms.
The related term 'digital phenotype' was introduced in Nature Biotechnology by Sachin H. Jain and John Brownstein in 2015.
Research platforms and commercialization
One of the first implementations of digital phenotyping on smart phones was the Funf Open Sensing Framework, developed at the MIT Media Lab and launched on October 5, 2011. Members of the Funf team interested in profiling and predicting human behavior formed a commercial venture called Behavio in 2012. In April 2013, it was announced that the Behavio team had joined Google. The Funf platform has inspired other mobile phone sensor logging platforms for psychology and behavior applications, such as the Purple Robot platform, developed by the CBITS (Center for Behavioral Intervention Technologies) at Northwestern University in 2012, which has since expanded and remains an active GITHUB project.
Among the academic research community, there are now many digital phenotyping platforms. Popular open-source digital phenotyping platforms include Beiwe, AWARE, EARS, mindLAMP, RADAR-CNS among others and there is currently no metric to determine which is most popular.
In terms of commercialization, in 2017, former head of the National Institutes of Mental Health, Tom Insel, joined Rick Klausner and Paul Dagum to form the founding team of MindStrong Health, which uses digital phenotyping methods combined with machine learning to develop new paradigms for mental health assessment and development of new digital biomarkers for mental health. As of 2021 the company's website does not mention digital phenotyping.
Criticisms
The widespread adoption of digital phenotyping across diverse research domains necessitates robust methodological guidelines. Passive data collection, a cornerstone of this approach, poses a significant challenges at every stage of the research process. From the outset, researchers grapple with clearly defining the constructs under investigation, a task complicated by the obscure nature of digital phenomena. Subsequent decisions about data capture devices, applications, and cleaning protocols further amplify the complexity. The analysis phase introduces another layer of challenges, particularly when employing computationally demanding techniques such as machine learning. Optimizing model performance through careful data partitioning and hyperparameter tuning is essential but requires essential knowledge. Recently published templates aim to address these challenges by providing standardized approaches to digital phenotyping research, potentially facilitating greater consistency and comparability across studies.
See also
John Brownstein
Jukka-Pekka Onnela
Sachin H. Jain
Scott L. Rauch
Mobile phone based sensing software
References
Further reading
JMIR e-collection Digital Biomarkers and Digital Phenotyping
Academic discipline interactions
Bioinformatics | Digital phenotyping | Engineering,Biology | 896 |
36,120,924 | https://en.wikipedia.org/wiki/Criticism%20of%20Myspace | The social networking service Myspace was among the most popular web sites in the 2000s decade. It has faced criticism on a variety of fronts, including for a massive redesign of the site in 2012 which occurred after the majority of original users had abandoned the website, misuse of the platform for cyber-bullying and harassment, risks for users' privacy, and major data losses.
Accessibility and reliability
Because most Myspace pages are designed by individuals with little HTML experience, a very large proportion of pages do not satisfy the criteria for valid HTML or CSS laid down by the W3C. Poorly formatted code can cause accessibility problems for those using software such as screen readers. The Myspace home page, as of May 20, 2009, failed HTML validation with around 101 errors (the number changes on sequential validations of the home page due to dynamic content), using the W3C's validator.
Furthermore, Myspace is set up so that anyone can customize the layout and colors of their profile page with virtually no restrictions, provided that the advertisements are not covered up by CSS or using other means. As Myspace users are usually not skilled web developers, this can cause further problems. Poorly constructed Myspace profiles could potentially freeze up web browsers due to malformed CSS coding, or as a result of users placing many high bandwidth objects such as videos, graphics, and Flash in their profiles (sometimes multiple videos and sound files are automatically played at the same time when a profile loads). While Myspace blocks potentially harmful code (such as JavaScript) from profiles, users have occasionally found ways to insert such code. PC World cited this as its main reason for naming Myspace as #1 in its list of twenty-five worst web sites ever.
Data loss
The website has experienced three major data losses: the removal of users' fans in early 2013, the unannounced removal of user blogs and private messages and videos in June 2013, and the loss of all music uploaded before 2016 which occurred in late 2017 or early 2018 and was widely reported in March 2019. More than fifty million music tracks were lost. After users started reporting music being unplayable, the MySpace developers initially reported trying to repair the problem, but later acknowledged that it was not possible. It was speculated that the data was deleted deliberately for economic reasons, and made to look accidental.
Security
In October 2005, a flaw in MySpace's site design was exploited by "Samy" to create the first self-propagating cross-site scripting (XSS) worm. MSNBC has reported that "social-networking sites like Myspace are turning out to be hotbeds for spyware," and "infection rates are on the rise, in part thanks to the surging popularity of social-networking sites like MySpace.com." In addition to this, the customization of user pages currently allows the injection of certain HTML which can be crafted to form a phishing user profile, thus keeping the Myspace.com domain as the address. A 2006 study showed that there has been spam on bulletins that has been the result of phishing. Users find their Myspace homepage with bulletins they did not post, realizing later they had been phished. The bulletin consists of an advertisement that provides a link to a fake login screen, tricking people into typing in their Myspace e-mail and password.
Other security fears regarding profile content itself are also present. For example, the embedding of videos inherently allows all of the format's abilities and functions to be used on a page. A prime example of this surfaced in December 2006, when embedded QuickTime videos were shown to contain hyperlinks to JavaScript files, which would be run simply by a user visiting a 'phished' profile page, or even in some cases by simply viewing a user's 'about me' elsewhere on the site. Users who entered their login information into a fake login bar that appeared would also become 'phished', and their account would be used to spam other members, thus spreading this security problem.
Myspace's anti-phishing and anti-spam measures have also come under fire. In 2007 Myspace made changes such that external links on profiles would be redirected through the http://msplinks.com domain. For example, http://en.wikipedia.org would be changed to http://www.msplinks.com/MDFodHRwOi8vZW4ud2lraXBlZGlhLm9yZw==http(The new links are determined by Base64 encoding, as there are ways of decoding the link back into its original URL.) Myspace staffers would be able to disable potentially dangerous links. (The changed links only work if the HTTP referrer is a Myspace page; otherwise, the link will appear to be disabled.) This move has been criticized that it makes profile editing inconvenient and that it does nothing to deter spammers. In February 2008 Myspace changed the system such that users who click such links (except for whitelisted domains like Wikipedia and YouTube) will receive a warning that they will be leaving the domain. As of March 2008, this "feature" has been extended to blogs as well, although previous blog entries are unaffected unless the user updates them.
On January 26, 2008, over 567,000 private Myspace user pictures were downloaded from the site by using a bug published on YouTube and put on the Piratebay torrent site for download.
In 2010, the company was criticized, along with other social networks, for passing user personally identifiable profile information to advertisers when members clicked on ads.
Privacy settings
MySpace has agreed to regular privacy check-ups for the next 20 years due to the fact it "misrepresented" the protection of those using the site and their personal information. The Federal Trade Commission wants to ensure sites truly protect their users and live up to stated standards. MySpace originally promised to not share users "identifiable information, or use such information in a way that was inconsistent with the purpose for which it was submitted, without first giving notice to users and receiving their permission." Despite these promises, MySpace gave advertisers personal information from current users, including: age, gender, profile picture, and username. Consequently, advertisers were able to locate a user's MySpace profile from the Friend ID to gain access to personal information from one's profile, such as the user's full name. This became increasingly dangerous for users and their safety because it leaked private information to the public.
MySpace, in 2010, provided users the option of controlling their individual privacy settings on their profile. In hope of regaining users from Facebook, MySpace is now simplifying their privacy settings. "The change is part of MySpace's new public commitment to privacy." The new privacy settings will allow users to restrict who sees their profile by limiting the accessibility to friends only, or people 18 or older. "Some people may have a private gathering in someone's home - that doesn't mean they're inviting everyone who happens to be friends of friends who are invited," said, Jeremy Mishkin, a partner and Internet privacy expert at the law firm Montgomery McCracken in Philadelphia. Third-party sites gaining access to user's personal private information has been a recurring theme amongst these social networks. Providing a safe social network with proper privacy settings, while also allowing users to be as social as they want, is the ideal system for all social media users.
Myspace party problems
Myspace is often used as a venue for publicizing parties, sometimes with the host's knowledge and sometimes without. There have been some well-publicized incidents where Myspace parties have caused thousands of dollars damage to property, and even (in at least one case) loss of life.
A party hosted by Corey Worthington, a sixteen-year-old boy from Narre Warren in Melbourne, Australia, and advertised on MySpace, attracted 500 people. Police cars were attacked, and the dog squad and a helicopter were called in. The incident received international coverage. (Worthington subsequently found work as a party promoter, and appeared on the Ten Network's Australian version of Big Brother.) The Sydney Morning Herald'''s online technology writer, Asher Moses, has noted that MySpace/Facebook parties are particularly prone to gatecrashing because news of events can spread to uninvited guests via "newsfeeds." He suspects some party hosts are oblivious to the actual number of people who get the message.
In April 2007, a seventeen-year-old British girl hosted a party after distributing information about it on Myspace that was reportedly subtitled "Let's trash the average family-sized house disco party." Her parents were left with an approximately £24,000 ($48,000) bill from police.
Allen Joplin, a seventeen-year-old American high school student from Seattle, was shot dead at a party that had been publicized through Myspace and attracted uninvited guests. A thirteen-year-old girl was injured in the same shooting.
Child safety
The minimum age to register an account on Myspace is 13, but it was 14 at one time and some still think of it as being 14. Profiles with ages set from 13 to 15 years are automatically private. Users whose ages are set at 16 or over have the option to set their profile to public viewing. Accessing the full profile of, or messaging someone when their account is set to "private" (or if under sixteen) is restricted to a Myspace user's direct friends.
Myspace will delete fake profiles if the victim verifies his or her identity and points out the profile via e-mail. In July 2007, the company found and deleted 29,000 profiles belonging to registered sex offenders.
Myspace has been the focus of a number of news reports stating that teenagers have found ways around the restrictions set by Myspace. Stricter methods for enforcing age admission will be enforced in the future, such as blocking a person from accessing Myspace using a computer's IP address. In response, Myspace has given assurances to parents that the website is safe for people of all ages. Beginning in late June 2006, Myspace users whose ages are set over 18 could no longer be able to add users whose ages are set from 13 to 15 years as friends unless they already know the user's full name or email address. Some third party Internet safety companies such as Social Shield have launched online communities for parents concerned about their child's safety on Myspace.
In June 2006, sixteen-year-old American Katherine Lester flew to the Middle East, to Tel Aviv, Israel, after having tricked her parents into getting her a passport in order to be with a twenty-year-old man she met through Myspace. U.S. officials in Jordan persuaded the teen to turn around and go home.
In October 2006, thirteen-year-old Megan Meier committed suicide after being the victim of cyber-bullying instigated by the mother of a friend who had posed as a sixteen-year-old named "Josh Evans".
In December 2006, Myspace announced new measures to protect children from known sex offenders. Although precise details were not given they said that "tools" would be implemented to prevent known sex offenders from the USA creating a Myspace profile.
In February 2007, a U.S. District Judge in Texas dismissed a case when a family sued MySpace for negligence, fraud, and misrepresentation; a girl in the family had been sexually assaulted by a man she met through MySpace, after she had misrepresented her age as 18 when she was 13. Regarding his dismissal of the case, U.S. District Judge Sam Sparks wrote: "If anyone had a duty to protect young girls, it was her parents, not MySpace."
In October 2007, a study published in the Journal of Adolescence conducted by Sameer Hinduja (Florida Atlantic University) and Justin W. Patchin (University of Wisconsin-Eau Claire) concluded that most adolescents use Myspace responsibly: "When considered in its proper context, these results indicate that the problem of personal information disclosure on Myspace may not be as widespread as many assume, and that the overwhelming majority of adolescents are responsibly using the website," they say.
Social and cultural
Dave Itzkoff, in the June 2006 Playboy magazine issue, related his experiences of experimentation with membership in Myspace. Among his other criticisms, one pertains to the distance afforded by the Internet that emboldens members, such as females who feature photos of themselves in scant clothing on their profile pages or behave in ways they would not in person, and he indicated that this duplicity undercuts the central design of MySpace, namely, to bring people together. Itzkoff also referenced the addictive, time-consuming nature of the site, mentioning that the Playboy'' Playmate and Myspace member Julie McCullough, who was the first to respond to his add-friend request, pointedly referred to the site as "cybercrack". Itzkoff argued that Myspace gives many people access to a member's life, without giving the time needed to maintain such relationships and that such relationships do not possess the depth of in-person relationships.
Furthermore, in terms of MySpace's potential for underhanded commercial exploitation, Itzkoff is particularly critical of the disturbing and fraudulent behavior of people who can contact a member, unsolicited, as when he was contacted by someone expressing a desire to socialize and date, but whose blog (to which Itzkoff was directed via subsequent emails) was found to be a solicitation for a series of commercial porn sites. Itzkoff is similarly critical of the more subtle commercial solicitations on the site, such as the banner ads and links to profiles and video clips that turn out to be, for example, commercials for new 20th Century Fox films. He also observed that MySpace's much-celebrated music section is heavily weighted in favor of record labels rather than breakthrough musicians.
In relating criticism from another person, whom Itzkoff called "Judas", he illustrated that, while the goal of attempting to bring together people who might not otherwise associate with one another in real life may seem honorable, Myspace inherently violates a social contract only present when people interact face-to-face, rendering, in his opinion, the website nothing more than a passing fad:
Controversy over corporate history
After the sale of Myspace to News Corp, Brad Greenspan (the former CEO, founder, and shareholder of Intermix Media the parent company that owned and launched MySpace.com) contested the sale of the company to News Corp. Greenspan claimed that new Intermix Media CEO Richard Rosenblatt and other board members cheated shareholders by selling the company for less than it was actually worth. Valleywag, a gossip blog that reported on the allegations, also claimed that founder and public face of MySpace, Tom Anderson, was a public relations invention. It was later confirmed by Newsweek that Anderson's age on the site had been lowered to "appeal" to younger users.
In October 2006, Greenspan published "The Myspace Report" on a personal website, calling for government investigation into News Corp's acquisition of Myspace. Greenspan's main allegation is that News Corp. should have valued Myspace at US$20 billion rather than US$327 million, and had defrauded Intermix shareholders through an unfair deal process. However the report was not widely accepted by the financial press and a lawsuit led by Greenspan challenging the acquisition was dismissed by a judge.
Censorship
Activist group MoveOn.org has criticized MySpace, claiming that the website practices censorship by not showing anti-media ads, removing fake profiles for high-profile media executives like Rupert Murdoch, and attempting to force users away from using certain third-party Flash applications on their profiles.
MySpace China
The simplified Chinese version of MySpace, launched in April 2007, has many censorship-related differences from other international versions of the service. Discussion forums on topics such as religion and politics are absent, and a filtering system that prevents the posting of content about Taiwan independence, the Dalai Lama, Falun Gong, and other "inappropriate topics" has been added. Users are also given the ability to report the "misconduct" of other users for offenses including "endangering national security, leaking state secrets, subverting the government, undermining national unity, and spreading rumors or disturbing the social order."
Religious and political discrimination
Throughout 2007 and 2008, Myspace was accused of deleting the "Atheist and Agnostic Group" on at least two occasions, deleting a pro-choice group, as well as banning individual Myspace users. The controversy stemmed from the belief that the groups and users had not violated the site's Terms of Service, and had been banned solely due to complaints from a smaller group of conservative religious users who were offended by the groups and members being on Myspace.
Blocking
Schools, public libraries, and employers in the United States, United Kingdom, France, Finland, Sweden, Germany, Russia, Australia and Malaysia have restricted access to Myspace, seeing it as "a haven for gossip and malicious comments."
A Catholic school in New Jersey has prohibited students from using Myspace at home, an action made to protect students from online predators as claimed by the school, although experts questioned the legality of such a ban and if it is constitutional. In autumn of 2005 Pope John XXIII Regional High School in Sparta Township, New Jersey made headlines by forbidding its students to have pages on Myspace or similar websites (such as Gaia) under threat of suspension or expulsion.
In Turkey, Myspace was blocked on September 19, 2009, due to copyright issues of MÜ-YAP. Turkish rock musician Aylin Aslım, who has a Myspace account said the block was a serious violation of rights for independent musicians of Turkey. On October 6 of the same year, the block was lifted.
Legal issues
In May 2006, Long Island, New York teenagers Shaun Harrison and Saverio Mondelli were charged with illegal computer access and attempted extortion of MySpace, after both had allegedly hacked into the site to steal the personal information of Myspace users before threatening to share the secrets of how they broke into the website unless Myspace paid them $150,000. Both teens were arrested by undercover Los Angeles police detectives posing as Myspace employees.
In April 2007, police in County Durham, United Kingdom, arrested a 17-year-old girl on charges of criminal damage following a party advertised on MySpace, held at her parents' house without their consent. Over 200 teenagers came to the party from across the country, causing £20,000 of damage, such as cigarette butts, urine on clothing, and writing on the walls. The girl's parents, who were away at the time, had to move out of the house.
Musicians' rights and Myspace terms of use agreement
Until June 2006, there was a concern amongst musicians, artists, and bands on Myspace such as songwriter Billy Bragg owing to the fine print within the user agreement that read, "You hereby grant to MySpace.com a non-exclusive, fully paid and royalty-free, worldwide license (with the right to sublicense through unlimited levels of sublicensees) to use, copy, modify, adapt, translate, publicly perform, publicly display, store, reproduce, transmit, and distribute such Content on and through the Services."
The fine print brought particular concern as the agreement was being made with Murdoch's News Corporation. Billy Bragg brought the issue to the attention of the media during the first week of June 2006. Jeff Berman, a Myspace spokesman swiftly responded by saying, "Because the legalese has caused some confusion, we are at work revising it to make it very clear that Myspace is not seeking a license to do anything with an artist's work other than allow it to be shared in the manner the artist intends."
By June 27, 2006, Myspace had amended the user agreement with, "MySpace.com does not claim any ownership rights in the text, files, images, photos, video, sounds, musical works, works of authorship, or any other materials (collectively, 'Content') that you post to the Myspace Services. After posting your Content to the Myspace Services, you continue to retain all ownership rights in such Content, and you continue to have the right to use your Content in any way you choose."
External links
Myspace from Archive Team wiki, a summary of the three major data losses.
References
Myspace
Myspace
Myspace | Criticism of Myspace | Technology | 4,201 |
20,603,786 | https://en.wikipedia.org/wiki/FU%20Orionis | FU Orionis is a variable and binary star system in the constellation of Orion, that in 1937 rose in apparent visual magnitude from 16.5 to 9.6, and has since been around magnitude 9. The name FU Orionis is a variable star designation in the Argelander system, which are assigned sequentially as new variables are discovered. FU Orionis is about 1,360 light years distant and is associated with the molecular cloud Barnard 35.
For a long time this variable was considered unique, but in 1970 a similar star, V1057 Cygni, was discovered, and a number of additional examples have been discovered since then. These stars constitute the FU Orionis class of variable stars, GCVS type FU, often nicknamed FUors. These stars are pre–main sequence stars which display an extreme change in magnitude and spectral type.
Stellar system
FU Orionis consists of two components, both surrounded by a circumstellar disk. Both disks were resolved with ALMA. The primary is surrounded by a dust disk with a radius of 11 astronomical units and the secondary disk has a similar inclination and size. The disks are separated by about 250 au. The 12CO emission show a complex kinematic environment and signatures of disk rotation, which are asymmetric. The asymmetry of the disk rotation is explained with interactions of the disks during a stellar flyby.
The primary, called FU Orionis north has a mass of 0.6 and accretes per year. The primary has an uncertain spectral type and luminosity class. FU Orionis stars do not show strong emission lines during the outburst and have spectral features that resemble F- or G-type supergiants during the maximum. The outer parts of FU Orionis stars produce a K-M supergiant spectrum, which can be observed in the near-infrared. The secondary, called FU Orionis south could be the more massive component in the system with 1.2 and a spectral type of about K5.
Nebula
FU Orionis is associated with the molecular cloud Barnard 35 (part of the Lambda Orionis Ring) and close to the star an arc-shaped nebula is visible. Other FU Orionis stars are associated with an arc-shaped reflection nebula that becomes visible as the star brightens.
Hypothetical planet
A 2023 study proposed that FU Orionis north might be accreting matter from an evaporating planet about 6 times the mass of Jupiter. Simulations predict an extremely large radius of or around at the beginning of the extreme evaporation event.
References
External links
AAVSO Variable Star of the Month. FU Ori: February 2002
FU Orionis at NightSkyInfo.com
FU Orionis stars
G-type supergiants
Orion (constellation)
Durchmusterung objects
Orionis, FU
Binary stars | FU Orionis | Astronomy | 567 |
5,054,730 | https://en.wikipedia.org/wiki/Biomolecular%20structure | Biomolecular structure is the intricate folded, three-dimensional shape that is formed by a molecule of protein, DNA, or RNA, and that is important to its function. The structure of these molecules may be considered at any of several length scales ranging from the level of individual atoms to the relationships among entire protein subunits. This useful distinction among scales is often expressed as a decomposition of molecular structure into four levels: primary, secondary, tertiary, and quaternary. The scaffold for this multiscale organization of the molecule arises at the secondary level, where the fundamental structural elements are the molecule's various hydrogen bonds. This leads to several recognizable domains of protein structure and nucleic acid structure, including such secondary-structure features as alpha helixes and beta sheets for proteins, and hairpin loops, bulges, and internal loops for nucleic acids.
The terms primary, secondary, tertiary, and quaternary structure were introduced by Kaj Ulrik Linderstrøm-Lang in his 1951 Lane Medical Lectures at Stanford University.
Primary structure
The primary structure of a biopolymer is the exact specification of its atomic composition and the chemical bonds connecting those atoms (including stereochemistry). For a typical unbranched, un-crosslinked biopolymer (such as a molecule of a typical intracellular protein, or of DNA or RNA), the primary structure is equivalent to specifying the sequence of its monomeric subunits, such as amino acids or nucleotides.
The primary structure of a protein is reported starting from the amino N-terminus to the carboxyl C-terminus, while the primary structure of DNA or RNA molecule is known as the nucleic acid sequence reported from the 5' end to the 3' end.
The nucleic acid sequence refers to the exact sequence of nucleotides that comprise the whole molecule. Often, the primary structure encodes sequence motifs that are of functional importance. Some examples of such motifs are: the C/D
and H/ACA boxes
of snoRNAs, LSm binding site found in spliceosomal RNAs such as U1, U2, U4, U5, U6, U12 and U3, the Shine-Dalgarno sequence,
the Kozak consensus sequence
and the RNA polymerase III terminator.
Secondary structure
The secondary structure of a protein is the pattern of hydrogen bonds in a biopolymer. These determine the general three-dimensional form of local segments of the biopolymers, but does not describe the global structure of specific atomic positions in three-dimensional space, which are considered to be tertiary structure. Secondary structure is formally defined by the hydrogen bonds of the biopolymer, as observed in an atomic-resolution structure. In proteins, the secondary structure is defined by patterns of hydrogen bonds between backbone amine and carboxyl groups (sidechain–mainchain and sidechain–sidechain hydrogen bonds are irrelevant), where the DSSP definition of a hydrogen bond is used.
The secondary structure of a nucleic acid is defined by the hydrogen bonding between the nitrogenous bases.
For proteins, however, the hydrogen bonding is correlated with other structural features, which has given rise to less formal definitions of secondary structure. For example, helices can adopt backbone dihedral angles in some regions of the Ramachandran plot; thus, a segment of residues with such dihedral angles is often called a helix, regardless of whether it has the correct hydrogen bonds. Many other less formal definitions have been proposed, often applying concepts from the differential geometry of curves, such as curvature and torsion. Structural biologists solving a new atomic-resolution structure will sometimes assign its secondary structure by eye and record their assignments in the corresponding Protein Data Bank (PDB) file.
The secondary structure of a nucleic acid molecule refers to the base pairing interactions within one molecule or set of interacting molecules. The secondary structure of biological RNA's can often be uniquely decomposed into stems and loops. Often, these elements or combinations of them can be further classified, e.g. tetraloops, pseudoknots and stem loops. There are many secondary structure elements of functional importance to biological RNA. Famous examples include the Rho-independent terminator stem loops and the transfer RNA (tRNA) cloverleaf. There is a minor industry of researchers attempting to determine the secondary structure of RNA molecules. Approaches include both experimental and computational methods (see also the List of RNA structure prediction software).
Tertiary structure
The tertiary structure of a protein or any other macromolecule is its three-dimensional structure, as defined by the atomic coordinates. Proteins and nucleic acids fold into complex three-dimensional structures which result in the molecules' functions. While such structures are diverse and complex, they are often composed of recurring, recognizable tertiary structure motifs and domains that serve as molecular building blocks. Tertiary structure is considered to be largely determined by the biomolecule's primary structure (its sequence of amino acids or nucleotides).
Quaternary structure
The protein quaternary structure refers to the number and arrangement of multiple protein molecules in a multi-subunit complex.
For nucleic acids, the term is less common, but can refer to the higher-level organization of DNA in chromatin, including its interactions with histones, or to the interactions between separate RNA units in the ribosome or spliceosome.
Viruses, in general, can be regarded as molecular machines. Bacteriophage T4 is a particularly well studied virus and its protein quaternary structure is relatively well defined. A study by Floor (1970) showed that, during the in vivo construction of the virus by specific morphogenetic proteins, these proteins need to be produced in balanced proportions for proper assembly of the virus to occur. Insufficiency (due to mutation) in the production of one particular morphogenetic protein (e.g. a critical tail fiber protein), can lead to the production of progeny viruses almost all of which have too few of the particular protein component to properly function, i.e. to infect host cells. However, a second mutation that reduces another morphogenetic component (e.g. in the base plate or head of the phage) could in some cases restore a balance such that a higher proportion of the virus particles produced are able to function. Thus it was found that a mutation that reduces expression of one gene, whose product is employed in morphogenesis, may be partially suppressed by a mutation that reduces expression of a second morphogenetic gene resulting in a more balanced production of the virus gene products. The concept that, in vivo, a balanced availability of components is necessary for proper molecular morphogenesis may have general applicability for understanding the assembly of protein molecular machines.
Structure determination
Structure probing is the process by which biochemical techniques are used to determine biomolecular structure. This analysis can be used to define the patterns that can be used to infer the molecular structure, experimental analysis of molecular structure and function, and further understanding on development of smaller molecules for further biological research. Structure probing analysis can be done through many different methods, which include chemical probing, hydroxyl radical probing, nucleotide analog interference mapping (NAIM), and in-line probing.
Protein and nucleic acid structures can be determined using either nuclear magnetic resonance spectroscopy (NMR) or X-ray crystallography or single-particle cryo electron microscopy (cryoEM). The first published reports for DNA (by Rosalind Franklin and Raymond Gosling in 1953) of A-DNA X-ray diffraction patterns—and also B-DNA—used analyses based on Patterson function transforms that provided only a limited amount of structural information for oriented fibers of DNA isolated from calf thymus. An alternate analysis was then proposed by Wilkins et al. in 1953 for B-DNA X-ray diffraction and scattering patterns of hydrated, bacterial-oriented DNA fibers and trout sperm heads in terms of squares of Bessel functions. Although the B-DNA form' is most common under the conditions found in cells, it is not a well-defined conformation but a family or fuzzy set of DNA conformations that occur at the high hydration levels present in a wide variety of living cells. Their corresponding X-ray diffraction & scattering patterns are characteristic of molecular paracrystals with a significant degree of disorder (over 20%), and the structure is not tractable using only the standard analysis.
In contrast, the standard analysis, involving only Fourier transforms of Bessel functions and DNA molecular models, is still routinely used to analyze A-DNA and Z-DNA X-ray diffraction patterns.
Structure prediction
Biomolecular structure prediction is the prediction of the three-dimensional structure of a protein from its amino acid sequence, or of a nucleic acid from its nucleobase (base) sequence. In other words, it is the prediction of secondary and tertiary structure from its primary structure. Structure prediction is the inverse of biomolecular design, as in rational design, protein design, nucleic acid design, and biomolecular engineering.
Protein structure prediction is one of the most important goals pursued by bioinformatics and theoretical chemistry. Protein structure prediction is of high importance in medicine (for example, in drug design) and biotechnology (for example, in the design of novel enzymes). Every two years, the performance of current methods is assessed in the Critical Assessment of protein Structure Prediction'' (CASP) experiment.
There has also been a significant amount of bioinformatics research directed at the RNA structure prediction problem. A common problem for researchers working with RNA is to determine the three-dimensional structure of the molecule given only the nucleic acid sequence. However, in the case of RNA, much of the final structure is determined by the secondary structure or intra-molecular base-pairing interactions of the molecule. This is shown by the high conservation of base pairings across diverse species.
Secondary structure of small nucleic acid molecules is determined largely by strong, local interactions such as hydrogen bonds and base stacking. Summing the free energy for such interactions, usually using a nearest-neighbor method, provides an approximation for the stability of given structure. The most straightforward way to find the lowest free energy structure would be to generate all possible structures and calculate the free energy for them, but the number of possible structures for a sequence increases exponentially with the length of the molecule. For longer molecules, the number of possible secondary structures is vast.
Sequence covariation methods rely on the existence of a data set composed of multiple homologous RNA sequences with related but dissimilar sequences. These methods analyze the covariation of individual base sites in evolution; maintenance at two widely separated sites of a pair of base-pairing nucleotides indicates the presence of a structurally required hydrogen bond between those positions. The general problem of pseudoknot prediction has been shown to be NP-complete.
Design
Biomolecular design can be considered the inverse of structure prediction. In structure prediction, the structure is determined from a known sequence, whereas, in protein or nucleic acid design, a sequence that will form a desired structure is generated.
Other biomolecules
Other biomolecules, such as polysaccharides, polyphenols and lipids, can also have higher-order structure of biological consequence.
See also
Biomolecular
Comparison of nucleic acid simulation software
Gene structure
List of RNA structure prediction software
Non-coding RNA
Notes
References
Biomolecules | Biomolecular structure | Chemistry,Biology | 2,376 |
30,387,975 | https://en.wikipedia.org/wiki/Islander%20%28database%29 | Islander is a database of integrative islands in prokaryotic genomes.
See also
Mobile genetic elements
References
External links
http://www.indiana.edu/~islander #BrokenLink
Mobile genetic elements
Biological databases | Islander (database) | Biology | 48 |
2,676,822 | https://en.wikipedia.org/wiki/Permanganic%20acid | Permanganic acid (or manganic(VII) acid) is the inorganic compound with the formula HMnO4 and various hydrates. This strong oxoacid has been isolated as its dihydrate. It is the conjugate acid of permanganate salts. It is the subject of few publications and its characterization as well as its uses are very limited.
Preparation and structure
Permanganic acid is most often prepared by the reaction of dilute sulfuric acid with a solution of barium permanganate, the insoluble barium sulfate byproduct being removed by filtering:
Ba(MnO4)2 + H2SO4 → 2 HMnO4 + BaSO4↓
The sulfuric acid used must be dilute; reactions of permanganates with concentrated sulfuric acid yield the anhydride, manganese heptoxide.
Permanganic acid has also been prepared through the reaction of hydrofluorosilicic acid with potassium permanganate, through electrolysis, and through hydrolysis of manganese heptoxide, though the last route often results in explosions.
Crystalline permanganic acid has been prepared at low temperatures as the dihydrate, HMnO4·2H2O.
Although its structure has not been verified spectroscopically or crystallographically, HMnO4 is assumed to be adopt a tetrahedral structure akin to that for perchloric acid.
Reactions
As a strong acid, HMnO4 is deprotonated to form the intensely purple coloured permanganates. Potassium permanganate, KMnO4, is a widely used, versatile and powerful oxidising agent.
Permanganic acid solutions are unstable, and gradually decompose into manganese dioxide, oxygen, and water, with initially formed manganese dioxide catalyzing further decomposition. Decomposition is accelerated by heat, light, and acids. Concentrated solutions decompose more rapidly than dilute.
References
Hydrogen compounds
Manganese(VII) compounds
Oxidizing acids
Mineral acids
Transition metal oxoacids | Permanganic acid | Chemistry | 430 |
4,705,345 | https://en.wikipedia.org/wiki/Pleiotrophin | Pleiotrophin (PTN) also known as heparin-binding brain mitogen (HBBM) or heparin-binding growth factor 8 (HBGF-8) or neurite growth-promoting factor 1 (NEGF1) or heparin affinity regulatory peptide (HARP) or heparin binding growth associated molecule (HB-GAM) is a protein that in humans is encoded by the PTN gene. Pleiotrophin is an 18-kDa growth factor that has a high affinity for heparin. It is structurally related to midkine and retinoic acid induced heparin-binding protein.
Function
Pleiotrophin was initially recognized as a neurite outgrowth-promoting factor present in rat brain around birth and as a mitogen toward fibroblasts isolated from bovine uterus tissue. Together with midkine these growth-factors constitute a family of (developmentally regulated) secreted heparin-binding proteins now known as the neurite growth-promoting factor (NEGF) family. During embryonic and early postnatal development, pleiotrophin is expressed in the central and peripheral nervous system and also in several non-neural tissues, notably lung, kidney, gut and bone. Pleiotrophin is also expressed by several tumor cells and is thought to be involved in tumor angiogenesis. In the adult central nervous system, pleiotrophin is expressed in an activity-dependent manner in the hippocampus where it can suppress long term potentiation induction. Pleiotrophin expression is low in other areas of the adult brain, but it can be induced by ischemic insults. or targeted neuronal damaged in the entorhinal cortex or in the substantia nigra pars compacta.
Clinical significance
Pleiotrophin binds to cell-surface nucleolin as a low affinity receptor. This binding can inhibit HIV infection.
References
Further reading
Growth factors
de:Wachstumsfaktor
es:Factor de crecimiento
fr:Facteur de croissance | Pleiotrophin | Chemistry | 440 |
19,403,762 | https://en.wikipedia.org/wiki/Ronald%20M.%20Foster | Ronald Martin Foster (3 October 1896 – 2 February 1998), was an American mathematician at Bell Labs whose work was of significance regarding electronic filters for use on telephone lines. He published an important paper, A Reactance Theorem, (see Foster's reactance theorem) which quickly inspired Wilhelm Cauer to begin his program of network synthesis filters which put the design of filters on a firm mathematical footing. He is also known for the Foster census of cubic, symmetric graphs and the 90-vertex cubic symmetric Foster graph.
Education
Foster was a Harvard College graduate S.B. (Mathematics), summa cum laude, Class of 1917. He also received two honorary Sc.D.s.
Professional career
1917 – 1943 Research & Development Department (later Bell Labs), American Telephone & Telegraph, as a Research Engineer (Applied Mathematician), New York City, New York.
1943 – 1963 Professor and Head of Department of Mathematics, Polytechnic Institute of Brooklyn, Brooklyn, New York City, New York.
Publications
Campbell, GA, Foster, RM, Fourier Integrals for Practical Applications, "Bell System Technical Journal", pp 639–707, 1928.
Pierce, BO, Foster. RM. "A Short Table of Integrals", Fourth Edition, Ginn and Company, pp 1–189, 1956.
References
1896 births
American men centenarians
Scientists at Bell Labs
American electronics engineers
20th-century American mathematicians
Graph theorists
Harvard College alumni
1998 deaths
Polytechnic Institute of New York University faculty
20th-century American engineers | Ronald M. Foster | Mathematics | 304 |
2,628,682 | https://en.wikipedia.org/wiki/Tornado%20outbreak | A tornado outbreak is the occurrence of multiple tornadoes spawned by the same synoptic scale weather system. The number of tornadoes required to qualify as an outbreak typically are at least six to ten, with at least two rotational locations (if squall line) or at least two supercells producing multiple tornadoes.
The tornadoes usually occur within the same day or continue into the early morning hours of the succeeding day, and within the same region. Most definitions allow for a break in tornado activity (time elapsed from the end of the last tornado to the beginning of the next tornado) of six hours. If tornado activity indeed resumes after such a lull, many definitions consider the event to be a new outbreak. A series of continuous or nearly continuous tornado outbreak days is a tornado outbreak sequence. In the United States and Canada, tornado outbreaks usually occur from March through June in the Great Plains, the Midwestern United States, and the Southeastern United States in an area colloquially referred to as Tornado Alley. Tornado outbreaks can also occur during other times of the year and in other parts of the world. A secondary less active and annually inconsistent tornado "season" in the U.S. occurs in late autumn.
Very large tornado outbreaks are known as super outbreaks. The largest tornado outbreak on record was the 2011 Super Outbreak, with 362 tornadoes and about $10 billion in direct damages. It surpassed the 1974 Super Outbreak, in which 148 tornadoes were counted. Both occurred within the United States and Canada. The total number of tornadoes is a problematic method of comparing outbreaks from different periods, however, as many more weaker tornadoes, but not stronger tornadoes, are reported in the US in recent decades than in previous ones due to improvements in tornado detection.
Tornado outbreak sequence
A tornado outbreak sequence, or tornado outbreak day sequence, sometimes referred to as an extended tornado outbreak, is a period of continuous or nearly continuous high tornado activity consisting of a series of tornado outbreaks over multiple days with no or very few days lacking tornado outbreaks.
Major tornado outbreak sequences occurred in the United States in May 1917, 1930, 1949, 1965, 1974, 2003, 2011, and 2024. Another exceptional outbreak sequence apparently occurred during mid to late May 1896. Although some days lacked tornado outbreaks, the period from mid to late April 2011 and late May 2019 also were periods of especially high tornado activity.
Tornado outbreak sequences tend to dominate the tornado statistics for a year and often cause a spike in tornado numbers for the entire year. Not all periods of active tornado occurrences are outbreak sequences, there must be no break in the activity to satisfy the definition. Active periods occur ranging from every year to every several years whereas continuously active periods are less common and can be rare depending on the parameters applied to define a sequence. By the late 2010s, medium to long range forecasting advanced sufficiently that some periods of high tornado activity can be somewhat reliably predicted several days to several weeks in advance.
See also
Lists of tornadoes and tornado outbreaks
Outbreak intensity score
References
Further reading
External links
US Violent Tornado Outbreak Statistics (SPC)
Tornado
Natural disasters | Tornado outbreak | Physics | 627 |
20,860,905 | https://en.wikipedia.org/wiki/Plane%20strain%20compression%20test | The plane strain compression test is a specialized test used on some materials ranging from metals to soils.
Metals
One variation of the test is also known as the Watts-Ford test. It is an engineering test, and is a particularly specialized way of determining some of the material characteristics of the metal being tested, and its specialization can be summarized by this quote:
The test is useful when the sheet pieces are too small for a tensile test of a balanced biaxial test. It can give stress-strain curves up to considerably higher strains than tensile tests.
Plane-strain compression testing is typically used for measuring mechanical properties and for exploring microstructure development in the course of thermomechanical treatment. During the test the specimen is placed between the punches and the constrain plates. When the upper punch is pushed down during the material test, the specimen is extended to horizontal directions. Friction between the tool and the specimen can be reduced by applying lubricants, such as graphite, MoS2, glass or PTFE(Teflon).
The testing essentially consists of a thin metal bar being compressed by two equally wide compressive strips, which are located of opposite sides of the thin bar. Then, over a range of increasing loads on the bar, the compressive forces lead to the thickness of the metal bar being reduced. This change of thickness is then measured sequentially after each loading, and after some mathematics a stress-strain curve can be plotted.
The advantages of the Watts-Ford test are that it is convenient for testing thin sheets or strips, it is similar to a rolling process (in manufacturing analyses), frictional effects may be minimized, there is no 'barrelling' as would occur in a cylindrical compression test, and the plane strain deformation eases the analysis.
Stress-strain curve
The stress-strain curve is the relationship between the stress (force per unit area) and strain (resulting compression/stretching, known as deformation) that a particular material displays; stress–strain curves of various materials differ widely, and different tensile tests conducted on the same material yield different results depending upon the temperature of the specimen and the speed of the loading. When performing Watts-Ford tests, temperatures of the metal specimens will vary from 800 to 1100 °C and strain rates of (0.01- 10 s-1).
Pressure
The average pressure on a unit of area of the contact surface between the punch and the specimen is expressed as: P= F/(wb), where F is force, w is the punch width, b is the specimen width.
See also
Compression (physics)
Compressive strength
Shear stress
Citations
Continuum mechanics
Materials testing | Plane strain compression test | Physics,Materials_science,Engineering | 541 |
31,271,471 | https://en.wikipedia.org/wiki/5-OH-DPAT | 5-OH-DPAT is a synthetic compound that acts as a dopamine receptor agonist with selectivity for the D2 receptor and D3 receptor subtypes. Only the (S)-enantiomer is active as an agonist, with the (R)-enantiomer being a weak antagonist at D2 receptors. Radiolabelled 11C-5-OH-DPAT is used as an agonist radioligand for mapping the distribution and function of D2 and D3 receptors in the brain, and the drug is also being studied in the treatment of Parkinson's disease.
See also
7-OH-DPAT
8-OH-DPAT
References
2-Aminotetralins
Hydroxyarenes
Dopamine agonists | 5-OH-DPAT | Chemistry | 163 |
69,831,323 | https://en.wikipedia.org/wiki/Dutch%20Schaefer | Major Alan "Dutch" Schaefer, commonly known simply as Dutch, is a fictional character in the Predator and Alien vs. Predator franchises, played by Arnold Schwarzenegger in the film Predator (1987) and the video game Predator: Hunting Grounds (2020), and voiced by James Patrick Cronin in the audiobook for Predator: Stalking Shadows (2020). A United States Army special forces operator, he first encounters a Yautja (Predator) in Predator when it massacres his crew of mercenaries in Val Verde, before he is recruited to join the OWLF (Other Worldly Life Forms Program) to hunt Yautja in Predator: South China Sea (2008), Stalking Shadows and Hunting Grounds, as Agent Onyx. Following his death, in Alien vs. Predator (1994), Dutch is rebuilt as an android by the United States Colonial Marine Corps, and he and his partner Linn Kurosawa join forces with two Yautja to fend off an invasion of xenomorphs.
The character has received a universally positive critical reception.
Fictional character biography
In Predator (1987)
In Predator (1987), Major Alan "Dutch" Schaefer is introduced as a highly skilled and experienced special forces operator who served in Vietnam during the Battle of Huế with CIA officer Al Dillon, now the leader of a mercenary group who operated in Afghanistan. After Dillon recruits Dutch and his team to go on a mission to Val Verde, purportedly to rescue a foreign cabinet minister and his aide from insurgents. En route, the team discovers the wreckage of a helicopter and three skinned corpses, whom Dutch identifies as Green Berets that he knew, leading him to become suspicious of Dillon's intentions. After the team reaches the guerilla camp and witness the execution of a hostage, Dutch leads them in mounting an attack, killing most of the rebels and several Soviet intelligence officers. Dutch confronts Dillon, who reveals their true mission was to stop a planned Soviet-backed invasion, the CIA having sent the Green Berets weeks earlier.
After capturing only surviving guerilla, Anna, and learning more rebels are coming, the team choose to trek to their extraction point on-foot. Unbeknownst to them, they are stalked by a Yautja, employing a cloaking device and thermal imaging technology, who kills one of Dutch's team while Anna is attempting to escape. After another team member is killed by the Yautja's plasma cannon, everyone is provoked to blindly fire their weapons into the jungle, unknowingly wounding the Yautja. Regrouping and realizing they are being hunted, Dutch and his commandoes make camp for the night and set traps, which are triggered by a wild boar. Dutch later realizes that their enemy uses the trees to travel and frees Anna, who states that her people had seen similarly mutilated bodies before. The next day, the group constructs a net trap and captures the Yautja, but it frees itself, killing everyone but Dutch and Anna as they flee. Realizing it does not attack unarmed individuals, Dutch tells the unarmed Anna to get to the chopper, before attempting to distract the Yautja by fleeing, ending up followed to a muddy riverbank and covered in mud. The Yautja fails to see him and leaves to collect trophies from the others. Dutch realizes the cool mud provided camouflage for his body heat. He crafts makeshift traps and weapons, and as he covers his body with additional mud for camouflage, before luring the Yautja out at night with a war cry and torch.
Dutch lightly injures the Yautja and disables its cloaking device as the Yautja fires wildly into the forest, and tries to escape, but accidentally falls into the river, where the water dissolves his muddy camouflage. As the Yautja corners Dutch, it removes its mask and plasma cannon to fight him hand-to-hand, having deemed him a worthy opponent. Despite being overpowered, outsmarted, battered, and bathed in his own blood he vomited, Dutch attempts to goad the Yautja into a booby trap he feels it won't see. It goes around after realising what Dutch was attempting to do, with this Dutch realises the counterweight is direct above the Yautja and kicks the supporting stick making the counterweight fall to earth, crushing the Yautja. With the monster mortally wounded, he asks it, "What the hell are you?". The Yautja repeats the question back to Dutch and activates its self-destruct device, imitating Billy's laugh as it counts down. Upon realizing what it has done, Dutch runs for cover and survives the explosion. He is then rescued by the extraction helicopter, with Anna already safely on board, though he is left traumatized by the experience.
In Predator 2 (1990)
In the novelisation of Predator 2 (1990), Dutch is revealed to have been spoken to by Agent Peter Keyes of the OWLF as he was infirmed in a hospital, suffering from radiation sickness from how close he had been to the Yautja's explosion at the conclusion of Predator. Dutch is said to have escaped from the hospital, never to be seen again.
In Alien vs. Predator (1994)
In Alien vs. Predator (1994), Dutch returns rebuilt as a synthetic android centuries following his death, with an enhanced cybernetic arm with a smart gun mounted on it, replicating one Dutch had installed as a human when he lost his arm. Having once again risen to the rank of Major in the United States Colonial Marine Corps, partnered with cybernetically enhanced Lieutenant Linn Kurosawa, Dutch and Linn are deployed to the city of San Drad, California after it is overrun with an army of xenomorphs, before they are abandoned by their superiors after their forces are seen to be too great. Just as Dutch and Lynn are about to be killed by a swarm of the xenomorph drones, a pair of Yautja (Predators) appear and destroy the xenomorphs, before offering an alliance with the two Marines in order to stop the alien infestation.
After destroying the xenomorph hive, Dutch and his team discover the xenomorph presence on Earth was the result of a bio-war project headed by the renegade General Bush of the Weyland-Yutani Corporation. Boarding Bush's military ship as it lifts off, Dutch, Lynn, and the Yautja kill the Xenomorph Queen after it kills Bush, and program the ship to crash into San Drad, triggering a huge explosion that eliminates all xenomorph life on Earth. The Yautja then gives Dutch and Lynn their wrist blades in recognition of their skills as warriors, before the Yautja depart back into space; after Linn asks the Yautja why they chose to help, their vague reply makes her and Dutch wonder whether they will have to fight them the next time they return to Earth.
In Predator: South China Sea (2008)
In Predator: South China Sea (2008), set years following the events of Predator, Dutch is depicted as "Agent Onyx", who had mentored former United States Special Forces operative John Gustat in killing Yautja after Gustat's wife and son had been killed by one, before tracking one down to an illegal hunting preserve on a private island in the South China Sea.
In Predator: Hunting Grounds (2020)
In Predator: Hunting Grounds (2020), set before his death, a series of tape recordings tell of Dutch's adventures between the events of Predator and Hunting Grounds: after being interviewed by Agent Peter Keyes, Dutch became obsessed with uncovering more about its species, ultimately learning it had been visiting Earth for "a very long time". By 1996, Dutch had set up yet another private military company dedicated to performing search and rescue operations, recruiting "haunted soldiers" whom he used as "bait" in his hunt for another Yautja, eventually encounter one in the Congo; in their subsequent encounter, Dutch's team and the Yautja were killed after one of his own stray bullets caught a crate of RPG ammunition, and Dutch faked his own death to avoid the OWLF, fleeing with a retrieved Yautja weapon. By the events of Predator 2, Dutch made his way to Los Angeles on deducing the current gang war and heat wave would be the perfect conditions for Yautja activity, arriving in the city shortly after the film's events. After being recaptured by the OWLF, he used his stolen Yautja technology to pressure the OWLF to "work with them, not for them" in the pursuit of Yautja; over the following decade, Dutch and the OWLF became good at hunting and killing Yautja in the middle of their hunts, retrieving more and more of their technology than ever before, before in 2008, Dutch had been spared by a female Yautja, who freed him from her netgun and disappeared into the jungle, leaving Dutch with a permanent grid shaped scar on the right side of his face, and a different image of how the Yautja operated. By 2018, Dutch is established as having been present as an offscreen character during the events of The Predator, present when the "Fugitive Predator" was captured by Project Stargazer, run by Cullen Yutani.
By 2025, the present-day narrative of Hunting Grounds, Dutch had begun working with the newly reinstated OWLF; after an encounter with another Yautja had left him critically wounded, he agreed to an experimental treatment to bond his DNA with that of a Yautja (as in Predator: Concrete Jungle), allowing him to continue fighting as a young man would at the age of 78, working with Peter Keyes' son Sean, and former Israeli Defense Forces sniper Isabelle Nissenbaum, who had previously been abducted to a "game reserve" planet (in Predators).
In Predator: Stalking Shadows (2020)
In Predator: Stalking Shadows (2020), following the events of Predator 2, Dutch chokes out U.S. Marine Scott Devlin after he comes across him recovering the hand Mike Harrigan had severed from the "City Hunter" Yautja, Over the course of the following years, bridging the events of Predator 2 and Hunting Grounds, Dutch continues to track Yautja incursions around the world, working in collusion with OWLF and assembling a new team of mercenaries to combat the creatures. During one such engagement in Malaysia, his group succeeds in killing a new, much more agile type of Yautja, albeit at the cost of several men, collecting its remains and any technology they can recover before making for home, which happens to be the base at which Devlin is stationed. Dutch subsequently arrives on the scene following Yautja hunts in Scotland and Mexico, which Devlin is also present for; placing his trust in Dutch, following the latter incident, Dutch approaches Devlin and reveals the truth behind the killings, recruiting him to his cause. Now promoted to the rank of captain, Devlin leads his unit in support of Dutch and his mercenaries on another operation in Mexico, securing a downed Yautja craft and killing one its occupants. Following the incident, Dutch disappears.
When Scott finally hears from Dutch again several years later, he learns Dutch's team was wiped out by a female Yautja in Laos, which then spared him to live with the shame of defeat. After saving Dutch from an attempted assassination, apparently organized by the Men in Black (MIB), who are also investigating the Yautja, Scott once again falls out of contact with him until another operation in Venezuela, in which they once again find evidence of Yautja activity before running into a team of MIBs. As the two groups face off, they are ambushed by the two Yautja responsible, which kill most of those present. Devlin is severely wounded but saved by Dutch, who finishes off the surviving Yautja with one of their own hand-held energy weapons. After Devlin recovers from his wounds, he is recruited by Dutch to run the OWLF's new operations command center, established in light of an increasing number of Yautja. Sometime later, in his office, Scott receives word from Dutch on an ongoing Yautja hunt in China.
Cancelled appearances
In the development of Predator 2 (1990), director Stephen Hopkins originally envisioned the film as a Patrick Swayze and Arnold Schwarzenegger buddy cop film, with the latter reprising his role as Dutch. Due to a dispute over salary and scheduling conflicts with Terminator 2: Judgment Day (1991), Schwarzenegger declined to return to the sequel. In October 2003, Schwarzenegger was reported to be interested in reprising his role as Dutch in a cameo role in Alien vs. Predator (2004) should he have lost the recall election to become Governor of California, on the condition the filming of his cameo took place at his residence; however, Schwarzenegger ultimately won the election with 48.58% of the votes, being unavailable to participate in the film. Robert Rodriguez hoped to have Schwarzenegger cameo as Dutch in Predators (2010), revealed in his originally scripted ending to have joined a Yautja hunting party, but this ultimately did not happen. In March 2011, Schwarzenegger revealed he was being considered to reprise his role as Dutch in a new Predator film, which ultimately entered development hell. Schwarzenegger also talked with Shane Black about potentially reprising his role as Dutch in a cameo role in The Predator (2018), in which he would have appeared in the final scene, saying "Come with me if you want to live." (a catchphrase of his Terminator character from the Terminator franchise) while inviting the protagonists to hunt Yautja, but declined the cameo due to the short role it would have been. Relatives of Dutch, his brother John Schaefer and great-great-granddaughter Psi-Judge Schaefer, are respectively featured in the comic series Predator: Concrete Jungle (1989–1990) and Predator vs. Judge Dredd (1997).
Merchandise
In 2013, NECA released an action figure collectable of Major Dutch Schaefer modelled off his appearance in Predator, while in 2018, NECA released a figure of Dutch based on his appearance in Alien vs. Predator. Also in 2018, an officially-licensed Predator brand of whiskey, named Dutch Bourbon Whiskey after Major Dutch Schaefer, was produced in collaboration between Fox Studios and the Silver Screen Bottling Company as promotion for The Predator (2018).
Reception
Entertainment Weekly said of Arnold Schwarzenegger's performance as Dutch in Predator (1987) that he has "never been as manly as he was in this alien-hunting testosterone-fest". IGN complimented the character's status as a "satire of the action film genre [that is] highly critical of the[se] kinds of characters [in] big, macho action movies, and the superficial, unquestioningly heroic stories they appear in". ScrewAttack included Dutch on their 2011 list of top ten space marines in video games for his depiction in Alien vs. Predator (1994), while Deja Reviewer described the title of Predator as "apply[ing] to both the alien being [and] Dutch" himself.
In popular culture
The line "Get to the choppa" used by Dutch in Predator was subsequently associated with Arnold Schwarzenegger, especially when Schwarzenegger said the line again in some of his later appearances, including The New Celebrity Apprentice and advertisements for the mobile video game Mobile Strike. Lieutenant Andrew Pierce – Christian Boeving's leading hero from the 2003 action film When Eagles Strike – was based on Schwarzenegger's image in the film. In the 2010 How It Should Have Ended episode "How Predator Should Have Ended" and the 2016 self-titled episode of After Credits, a parodic retelling of the events of Predator, Dutch is voiced by Daniel Baxter.
Appearances
Predator (1987)
Predator 2 (1990 novelisation)
Alien vs. Predator (1994)
Predator: Dark River (1996)
Sci-Fi Pinball (1999)
Predator: South China Sea (2008)
Predators: Beating the Bullet (2010)
AVP: The Hunt Begins (2019)
Predator: Hunting Grounds (2020)
Predator: Stalking Shadows (2020)
Predator: Eyes of the Demon: Aftermath (2022)
References
External links
Major Dutch Schaefer at Alien vs. Predator
Predator (franchise) characters
Alien vs. Predator (franchise) characters
Action film characters
Fictional amputees
Fictional androids
Fictional characters with post-traumatic stress disorder
Fictional characters with superhuman strength
Fictional cyborgs
Fictional hybrids
Fictional majors
Fictional mercenaries
Fictional soldiers
Fictional sole survivors
Fictional United States Army Special Forces personnel
Film characters introduced in 1987
Male horror film characters
Science fiction film characters
Space marines | Dutch Schaefer | Biology | 3,456 |
75,768,013 | https://en.wikipedia.org/wiki/Cost-sensitive%20machine%20learning | Cost-sensitive machine learning is an approach within machine learning that considers varying costs associated with different types of errors. This method diverges from traditional approaches by introducing a cost matrix, explicitly specifying the penalties or benefits for each type of prediction error. The inherent difficulty which cost-sensitive machine learning tackles is that minimizing different kinds of classification errors is a multi-objective optimization problem.
Overview
Cost-sensitive machine learning optimizes models based on the specific consequences of misclassifications, making it a valuable tool in various applications. It is especially useful in problems with a high imbalance in class distribution and a high imbalance in associated costs
Cost-sensitive machine learning introduces a scalar cost function in order to find one (of multiple) Pareto optimal points in this multi-objective optimization problem.
Cost Matrix
The cost matrix is a crucial element within cost-sensitive modeling, explicitly defining the costs or benefits associated with different prediction errors in classification tasks. Represented as a table, the matrix aligns true and predicted classes, assigning a cost value to each combination. For instance, in binary classification, it may distinguish costs for false positives and false negatives. The utility of the cost matrix lies in its application to calculate the expected cost or loss. The formula, expressed as a double summation, utilizes joint probabilities:
Here, denotes the joint probability of actual class and predicted class , providing a nuanced measure that considers both the probabilities and associated costs. This approach allows practitioners to fine-tune models based on the specific consequences of misclassifications, adapting to scenarios where the impact of prediction errors varies across classes.
Applications
Fraud Detection
In the realm of data science, particularly in finance, cost-sensitive machine learning is applied to fraud detection. By assigning different costs to false positives and false negatives, models can be fine-tuned to minimize the overall financial impact of misclassifications.
Medical Diagnostics
In healthcare, cost-sensitive machine learning plays a role in medical diagnostics. The approach allows for customization of models based on the potential harm associated with misdiagnoses, ensuring a more patient-centric application of machine learning algorithms.
Challenges
A typical challenge in cost-sensitive machine learning is the reliable determination of the cost matrix which may evolve over time.
Literature
Cost-Sensitive Machine Learning. USA, CRC Press, 2011.
Abhishek, K., Abdelaziz, D. M. (2023). Machine Learning for Imbalanced Data: Tackle Imbalanced Datasets Using Machine Learning and Deep Learning Techniques. (n.p.): Packt Publishing.
References
Machine learning | Cost-sensitive machine learning | Engineering | 540 |
34,519,332 | https://en.wikipedia.org/wiki/Service%20virtualization | In software engineering, service virtualization or service virtualisation is a method to emulate the behavior of specific components in heterogeneous component-based applications such as API-driven applications, cloud-based applications and service-oriented architectures.
It is used to provide software development and QA/testing teams access to dependent system components that are needed to exercise an application under test (AUT), but are unavailable or difficult-to-access for development and testing purposes. With the behavior of the dependent components "virtualized", testing and development can proceed without accessing the actual live components.
Service virtualization is recognized by vendors, industry analysts, and industry publications as being different than mocking. See here for a Comparison of API simulation tools.
Overview
Service virtualization emulates the behavior of software components to remove dependency constraints on development and testing teams. Such constraints occur in complex, interdependent environments when a component connected to the application under test is:
Not yet completed
Still evolving
Controlled by a third-party or partner
Available for testing only in limited capacity or at inconvenient times
Difficult to provision or configure in a test environment
Needed for simultaneous access by different teams with varied test data setup and other requirements
Restricted or costly to use for load and performance testing
Although the term "service virtualization" reflects the technique's initial focus on virtualizing web services, service virtualization extends across all aspects of composite applications: services, databases, mainframes, ESBs, and other components that communicate using common messaging protocols. Other similar tools are called API simulators, API mocking tools, over the wire test doubles.
Service virtualization emulates only the behavior of the specific dependent components that developers or testers need to exercise in order to complete their end-to-end transactions.
Rather than virtualizing entire systems, it virtualizes only specific slices of dependent behavior critical to the execution of development and testing tasks. This provides just enough application logic so that the developers or testers get what they need without having to wait for the actual service to be completed and readily available. For instance, instead of virtualizing an entire database (and performing all associated test data management as well as setting up the database for every test session), you monitor how the application interacts with the database, then you emulate the related database behavior (the SQL queries that are passed to the database, the corresponding result sets that are returned, and so forth).
Application
Service virtualization involves creating and deploying a "virtual asset" that simulates the behavior of a real component which is required to exercise the application under test, but is difficult or impossible to access for development and testing purposes.
A virtual asset stands in for a dependent component by listening for requests and returning an appropriate response—with the appropriate performance. For a database, this might involve listening for a SQL statement, then returning data source rows. For a web service, this might involve listening for an XML message over HTTP, JMS, or MQ, then returning another XML message. The virtual asset's functionality and performance might reflect the actual functionality/performance of the dependent component, or it might simulate exceptional conditions (such as extreme loads or error conditions) to determine how the application under test responds under those circumstances.
Virtual assets are typically created by:
Recording live communication among components as the system is exercised from the application under test (AUT)
Providing logs representing historical communication among components
Analyzing service interface specifications (such as a WSDL)
Defining the behavior manually with various interface controls and data source values
They are then further configured to represent specific data, functionality, and response times.
Virtual assets are deployed locally or in the cloud (public or private). With development/test environments configured to use the virtual assets in place of dependent components, developers or testers can then exercise the application they are working on without having to wait for the dependent components to be completed or readily accessible.
Industry analysts report that service virtualization is best suited for "IT shops with significant experience with 'skipping' integration testing due to 'dependent software', and with a reasonably sophisticated test harness.
Relation to stubbing and mocking
An alternative approach to working around the test environment access constraints outlined in this article's introduction is for team members to develop method stubs or mock objects that substitute for dependent resources. The shortcoming of this approach became apparent in the early 2000s with the rise of Service-oriented architecture. The proliferation of Composite applications that rely on numerous dependent services, plus the rise of Agile software development following the 2001 publication of the Agile Manifesto, made it increasingly difficult for developers or testers to manually develop the number, scope, and complexity of stubs or mocks required to complete development and testing tasks for modern enterprise application development.
The first step in the evolution from stubbing to service virtualization was the technology packaged in SOA testing tools since 2002. The earliest implementations of service virtualization were designed to automate the process of developing simple stub-like emulations so that composite applications could be tested more efficiently. As enterprise systems continued to grow increasingly complex and distributed, software tool vendors shifted focus from stubbing to the more environment-focused service virtualization. While stubbing can still be completed through manual development and management of stubs, what has become known as "service virtualization" is completed by using one of the available commercial off the shelf (COTS) service virtualization technologies as a platform for the development and deployment of their "service virtualization assets".
Agile and DevOps
The increasing popularity of Agile software development and DevOps has created demand for a new set of tools to deliver service virtualization to communities that work in this way. Practices such as Continuous delivery and moving away from mainframe and monolith development to more distributed microservice-based architectures fit well with the capabilities of service virtualization. Agile and DevOps teams prefer to work with lightweight tools that have less accumulated bloat and no cumbersome licensing restrictions.
See also
Comparison of API simulation tools
Test double
Digital twin
References
Software testing
Quality assurance | Service virtualization | Engineering | 1,229 |
1,192,012 | https://en.wikipedia.org/wiki/Green%27s%20relations | In mathematics, Green's relations are five equivalence relations that characterise the elements of a semigroup in terms of the principal ideals they generate. The relations are named for James Alexander Green, who introduced them in a paper of 1951. John Mackintosh Howie, a prominent semigroup theorist, described this work as "so all-pervading that, on encountering a new semigroup, almost the first question one asks is 'What are the Green relations like?'" (Howie 2002). The relations are useful for understanding the nature of divisibility in a semigroup; they are also valid for groups, but in this case tell us nothing useful, because groups always have divisibility.
Instead of working directly with a semigroup S, it is convenient to define Green's relations over the monoid S1. (S1 is "S with an identity adjoined if necessary"; if S is not already a monoid, a new element is adjoined and defined to be an identity.) This ensures that principal ideals generated by some semigroup element do indeed contain that element. For an element a of S, the relevant ideals are:
The principal left ideal generated by a: . This is the same as , which is .
The principal right ideal generated by a: , or equivalently .
The principal two-sided ideal generated by a: , or .
The L, R, and J relations
For elements a and b of S, Green's relations L, R and J are defined by
a L b if and only if S1 a = S1 b.
a R b if and only if a S1 = b S1.
a J b if and only if S1 a S1 = S1 b S1.
That is, a and b are L-related if they generate the same left ideal; R-related if they generate the same right ideal; and J-related if they generate the same two-sided ideal. These are equivalence relations on S, so each of them yields a partition of S into equivalence classes. The L-class of a is denoted La (and similarly for the other relations). The L-classes and R-classes can be equivalently understood as the strongly connected components of the left and right Cayley graphs of S1. Further, the L, R, and J relations define three preorders ≤L, ≤R, and ≤J, where a ≤J b holds for two elements a and b of S if the ideal generated by a is included in that of b, i.e., S1 a S1 ⊆ S1 b S1, and ≤L and ≤R are defined analogously.
Green used the lowercase blackletter , and for these relations, and wrote for a L b (and likewise for R and J). Mathematicians today tend to use script letters such as instead, and replace Green's modular arithmetic-style notation with the infix style used here. Ordinary letters are used for the equivalence classes.
The L and R relations are left-right dual to one another; theorems concerning one can be translated into similar statements about the other. For example, L is right-compatible: if a L b and c is another element of S, then ac L bc. Dually, R is left-compatible: if a R b, then ca R cb.
If S is commutative, then L, R and J coincide.
The H and D relations
The remaining relations are derived from L and R. Their intersection is H:
a H b if and only if a L b and a R b.
This is also an equivalence relation on S. The class Ha is the intersection of La and Ra. More generally, the intersection of any L-class with any R-class is either an H-class or the empty set.
Green's Theorem states that for any -class H of a semigroup S either (i) or (ii) and H is a subgroup of S. An important corollary is that the equivalence class He, where e is an idempotent, is a subgroup of S (its identity is e, and all elements have inverses), and indeed is the largest subgroup of S containing e. No -class can contain more than one idempotent, thus is idempotent separating. In a monoid M, the class H1 is traditionally called the group of units. (Beware that unit does not mean identity in this context, i.e. in general there are non-identity elements in H1. The "unit" terminology comes from ring theory.) For example, in the transformation monoid on n elements, Tn, the group of units is the symmetric group Sn.
Finally, D is defined: a D b if and only if there exists a c in S such that a L c and c R b. In the language of lattices, D is the join of L and R. (The join for equivalence relations is normally more difficult to define, but is simplified in this case by the fact that a L c and c R b for some c if and only if a R d and d L b for some d.)
As D is the smallest equivalence relation containing both L and R, we know that a D b implies a J b—so J contains D. In a finite semigroup, D and J are the same, as also in a rational monoid. Furthermore they also coincide in any epigroup.
There is also a formulation of D in terms of equivalence classes, derived directly from the above definition:
a D b if and only if the intersection of Ra and Lb is not empty.
Consequently, the D-classes of a semigroup can be seen as unions of L-classes, as unions of R-classes, or as unions of H-classes. Clifford and Preston (1961) suggest thinking of this situation in terms of an "egg-box":
Each row of eggs represents an R-class, and each column an L-class; the eggs themselves are the H-classes. For a group, there is only one egg, because all five of Green's relations coincide, and make all group elements equivalent. The opposite case, found for example in the bicyclic semigroup, is where each element is in an H-class of its own. The egg-box for this semigroup would contain infinitely many eggs, but all eggs are in the same box because there is only one D-class. (A semigroup for which all elements are D-related is called bisimple.)
It can be shown that within a D-class, all H-classes are the same size. For example, the transformation semigroup T4 contains four D-classes, within which the H-classes have 1, 2, 6, and 24 elements respectively.
Recent advances in the combinatorics of semigroups have used Green's relations to help enumerate semigroups with certain properties. A typical result (Satoh, Yama, and Tokizawa 1994) shows that there are exactly 1,843,120,128 non-equivalent semigroups of order 8, including 221,805 that are commutative; their work is based on a systematic exploration of possible D-classes. (By contrast, there are only five groups of order 8.)
Example
The full transformation semigroup T3 consists of all functions from the set {1, 2, 3} to itself; there are 27 of these. Write (a b c) for the function that sends 1 to a, 2 to b, and 3 to c. Since T3 contains the identity map, (1 2 3), there is no need to adjoin an identity.
The egg-box diagram for T3 has three D-classes. They are also J-classes, because these relations coincide for a finite semigroup.
In T3, two functions are L-related if and only if they have the same image. Such functions appear in the same column of the table above. Likewise, the functions f and g are R-related if and only if
f(x) = f(y) ⇔ g(x) = g(y)
for x and y in {1, 2, 3}; such functions are in the same table row. Consequently, two functions are D-related if and only if their images are the same size.
The elements in bold are the idempotents. Any H-class containing one of these is a (maximal) subgroup. In particular, the third D-class is isomorphic to the symmetric group S3. There are also six subgroups of order 2, and three of order 1 (as well as subgroups of these subgroups). Six elements of T3 are not in any subgroup.
Generalisations
There are essentially two ways of generalising an algebraic theory. One is to change its definitions so that it covers more or different objects; the other, more subtle way, is to find some desirable outcome of the theory and consider alternative ways of reaching that conclusion.
Following the first route, analogous versions of Green's relations have been defined for semirings (Grillet 1970) and rings (Petro 2002). Some, but not all, of the properties associated with the relations in semigroups carry over to these cases. Staying within the world of semigroups, Green's relations can be extended to cover relative ideals, which are subsets that are only ideals with respect to a subsemigroup (Wallace 1963).
For the second kind of generalisation, researchers have concentrated on properties of bijections between L- and R- classes. If x R y, then it is always possible to find bijections between Lx and Ly that are R-class-preserving. (That is, if two elements of an L-class are in the same R-class, then their images under a bijection will still be in the same R-class.) The dual statement for x L y also holds. These bijections are right and left translations, restricted to the appropriate equivalence classes. The question that arises is: how else could there be such bijections?
Suppose that Λ and Ρ are semigroups of partial transformations of some semigroup S. Under certain conditions, it can be shown that if x Ρ = y Ρ, with x ρ1 = y and y ρ2 = x, then the restrictions
ρ1 : Λ x → Λ y
ρ2 : Λ y → Λ x
are mutually inverse bijections. (Conventionally, arguments are written on the right for Λ, and on the left for Ρ.) Then the L and R relations can be defined by
x L y if and only if Λ x = Λ y
x R y if and only if x Ρ = y Ρ
and D and H follow as usual. Generalisation of J is not part of this system, as it plays no part in the desired property.
We call (Λ, Ρ) a Green's pair. There are several choices of partial transformation semigroup that yield the original relations. One example would be to take Λ to be the semigroup of all left translations on S1, restricted to S, and Ρ the corresponding semigroup of restricted right translations.
These definitions are due to Clark and Carruth (1980). They subsume Wallace's work, as well as various other generalised definitions proposed in the mid-1970s. The full axioms are fairly lengthy to state; informally, the most important requirements are that both Λ and Ρ should contain the identity transformation, and that elements of Λ should commute with elements of Ρ.
See also
Schutzenberger group
References
C. E. Clark and J. H. Carruth (1980) Generalized Green's theories, Semigroup Forum 20(2); 95–127.
A. H. Clifford and G. B. Preston (1961) The Algebraic Theory of Semigroups, volume 1, (1967) volume 2, American Mathematical Society, Green's relations are introduced in Chapter 2 of the first volume.
J. A. Green (July 1951) "On the structure of semigroups", Annals of Mathematics (second series) 54(1): 163–172.
John M. Howie (1976) An introduction to Semigroup Theory, Academic Press . An updated version is available as Fundamentals of Semigroup Theory, Oxford University Press, 1995. .
John M. Howie (2002) "Semigroups, Past, Present and Future", Proceedings of the International Conference on Algebra and its Applications, Chulalongkorn University, Thailand
Petraq Petro (2002) Green's relations and minimal quasi-ideals in rings, Communications in Algebra 30(10): 4677–4686.
S. Satoh, K. Yama, and M. Tokizawa (1994) "Semigroups of order 8", Semigroup Forum 49: 7–29.
Semigroup theory | Green's relations | Mathematics | 2,677 |
58,693,851 | https://en.wikipedia.org/wiki/Aspergillus%20puniceus | Aspergillus puniceus is a species of fungus in the genus Aspergillus. It is from the Usti section. The species was first described in 1965.
Growth and morphology
A. puniceus has been cultivated on both Czapek yeast extract agar (CYA) plates and Malt Extract Agar Oxoid® (MEAOX) plates. The growth morphology of the colonies can be seen in the pictures below.
References
puniceus
Fungi described in 1965
Fungus species | Aspergillus puniceus | Biology | 104 |
13,246,733 | https://en.wikipedia.org/wiki/Institute%20for%20Materials%20Research | , abbreviated IMR or , is a research institute for materials science in the Tohoku University, Japan. It consistently ranks as one of the top in ISI citations on materials research. In 2001, it ranked first in the field of materials science by ISI, Philadelphia .
Outline
The institute is the oldest of the five research institutes of Tohoku University. It was started 90 years ago by the late Professor Kotaro Honda for research on KS steel. In 1987, it was reorganized into its present form, a national collaborative research institute, and designated as a Center of Excellence (COE) for materials science.
IMR's research field is diverse materials as well as metals. Some of its recent creations include new types of materials, including high-performance, high-quality and multifunctional materials such as amorphous alloys with complex structures, and bulk metallic glasses developed from them. The institute also specialises in multicomponent intermetallic compounds, quasicrystals, oxides, ceramics, nanostructural controlled metals, semiconductors, crystals for solar cells, biomaterials, organic materials, hydrogen storage alloys, and shaped crystals, among others.
Former names
The present name of the institute is the Institute for Materials Research (IMR).
April 1, 1916: the 2nd Division of the Provisional Institute of Physical and Chemical Research(東北帝国大学理科大学臨時理化学研究所第2部)
May 21, 1919: the Iron and Steel Research Institute (ISRI)(東北帝国大学附属鉄鋼研究所)
August 8, 1922: the Research Institute for Iron, Steel and Other Metals (RIISOM)(東北帝国大学金属材料研究所, 東北大学金属材料研究所1947)
May 21, 1987: Institute for Materials Research (IMR)
Research results
Refer to this page.
People
Presidents
Researchers
Refer to this page.
The institute has produced many world-famous researchers. Akihisa Inoue, the 18th president of Tohoku University, is well-known for his work on bulk metallic glasses. The Institute of Scientific Information (ISI) has named him as one of the most cited researchers in materials science and engineering, with just two of his publications being the 2nd and 8th most highly-cited in the field. Inoue was awarded the 2006 Prime Minister's Prize for this research, and the 2009 James C. McGroddy Prize for New Materials from the American Physical Society.
Facilities and laboratories
Refer to this page.
Address
1-1-2-chome, Katahira, Aoba-ku, Sendai, Miyagi 980-8577 JAPAN
See also
Tohoku University
Research Institute of Electronic Communication
Institute of Development, Aging and Cancer
External links
IMR official website
References
Tohoku University website
Tohoku University
Research institutes in Japan
Materials science institutes
1916 establishments in Japan | Institute for Materials Research | Materials_science | 608 |
37,983 | https://en.wikipedia.org/wiki/Typex | In the history of cryptography, Typex (alternatively, Type X or TypeX) machines were British cipher machines used from 1937. It was an adaptation of the commercial German Enigma with a number of enhancements that greatly increased its security. The cipher machine (and its many revisions) was used until the mid-1950s when other more modern military encryption systems came into use.
Description
Like Enigma, Typex was a rotor machine. Typex came in a number of variations, but all contained five rotors, as opposed to three or four in the Enigma. Like the Enigma, the signal was sent through the rotors twice, using a "reflector" at the end of the rotor stack. On a Typex rotor, each electrical contact was doubled to improve reliability.
Of the five rotors, typically the first two were stationary. These provided additional enciphering without adding complexity to the rotor turning mechanisms. Their purpose was similar to the plugboard in the Enigmas, offering additional randomization that could be easily changed. Unlike Enigma's plugboard, however, the wiring of those two rotors could not be easily changed day-to-day. Plugboards were added to later versions of Typex.
The major improvement the Typex had over the standard Enigma was that the rotors in the machine contained multiple notches that would turn the neighbouring rotor. This eliminated an entire class of attacks on the system, whereas Enigma's fixed notches resulted in certain patterns appearing in the cyphertext that could be seen under certain circumstances.
Some Typex rotors came in two parts, where a slug containing the wiring was inserted into a metal casing. Different casings contained different numbers of notches around the rim, such as 5, 7 or 9 notches. Each slug could be inserted into a casing in two different ways by turning it over. In use, all the rotors of the machine would use casings with the same number of notches. Normally five slugs were chosen from a set of ten.
On some models, operators could achieve a speed of 20 words a minute, and the output ciphertext or plaintext was printed on paper tape. For some portable versions, such as the Mark III, a message was typed with the left hand while the right hand turned a handle.
Several Internet Typex articles say that only Vaseline was used to lubricate Typex machines and that no other lubricant was used. Vaseline was used to lubricate the rotor disc contacts. Without this there was a risk of arcing which would burn the insulation between the contacts. For the rest of the machine two grades of oil (Spindle Oils 1 and 2) were used. Regular cleaning and maintenance was essential.
In particular, the letters/figures cam-cluster balata discs had to be kept lubricated.
History and development
By the 1920s, the British Government was seeking a replacement for its book cipher systems, which had been shown to be insecure and which proved to be slow and awkward to use. In 1926, an inter-departmental committee was formed to consider whether they could be replaced with cipher machines. Over a period of several years and at large expense, the committee investigated a number of options but no proposal was decided upon. One suggestion was put forward by Wing Commander Oswyn G. W. G. Lywood to adapt the commercial Enigma by adding a printing unit but the committee decided against pursuing Lywood's proposal.
In August 1934, Lywood began work on a machine authorised by the RAF. Lywood worked with J. C. Coulson, Albert P. Lemmon, and Ernest W. Smith at Kidbrooke in Greenwich, with the printing unit provided by Creed & Company. The first prototype was delivered to the Air Ministry on 30 April 1935. In early 1937, around 30 Typex Mark I machines were supplied to the RAF. The machine was initially termed the "RAF Enigma with Type X attachments".
The design of its successor had begun by February 1937. In June 1938, Typex Mark II was demonstrated to the cipher-machine committee, who approved an order of 350 machines. The Mark II model was bulky, incorporating two printers: one for plaintext and one for ciphertext. As a result, it was significantly larger than the Enigma, weighing around , and measuring × × . After trials, the machine was adopted by the RAF, Army and other government departments. During World War II, a large number of Typex machines were manufactured by the tabulating machine manufacturer Powers-Samas.
Typex Mark III was a more portable variant, using the same drums as the Mark II machines powered by turning a handle (it was also possible to attach a motor drive). The maximum operating speed is around 60 letters a minute, significantly slower than the 300 achievable with the Mark II.
Typex Mark VI was another handle-operated variant, measuring × ×, weighing and consisting of over 700 components.
Plugboards for the reflector were added to the machine from November 1941.
For inter-Allied communications during World War II, the Combined Cipher Machine (CCM) was developed, used in the Royal Navy from November 1943. The CCM was implemented by making modifications to Typex and the United States ECM Mark II machine so that they would be compatible.
Typex Mark VIII was a Mark II fitted with a morse perforator.
Typex 22 (BID/08/2) and Typex 23 (BID/08/3) were late models, that incorporated plugboards for improved security. Mark 23 was a Mark 22 modified for use with the CCM. In New Zealand, Typex Mark II and Mark III were superseded by Mark 22 and Mark 23 on 1 January 1950. The Royal Air Force used a combination of the Creed Teleprinter and Typex until 1960. This amalgamation allowed a single operator to use punch tape and printouts for both sending and receiving encrypted material.
Erskine (2002) estimates that around 12,000 Typex machines were built by the end of World War II.
Security and use
Less than a year into the war, the Germans could read all British military encryption other than Typex, which was used by the British armed forces and by Commonwealth countries including Australia, Canada and New Zealand. The Royal Navy decided to adopt the RAF Type X Mark II in 1940 after trials; eight stations already had Type X machines. Eventually over 600 machines would be required. New Zealand initially got two machines at a cost of £115 (GBP) each for Auckland and Wellington.
From 1943 the Americans and the British agreed upon a Combined Cipher Machine (CCM). The British Typex and American ECM Mark II could be adapted to become interoperable. While the British showed Typex to the Americans, the Americans never permitted the British to see the ECM, which was a more complex design. Instead, attachments were built for both that allowed them to read messages created on the other.
In 1944 the Admiralty decided to supply 2 CCM Mark III machines (the Typex Mark II with adaptors for the American CCM) for each "major" war vessel down to and including corvettes but not submarines; RNZN vessels were the Achilles, Arabis (then out of action), Arbutus, Gambia and Matua.
Although a British test cryptanalytic attack made considerable progress, the results were not as significant as against the Enigma, due to the increased complexity of the system and the low levels of traffic.
A Typex machine without rotors was captured by German forces at Dunkirk during the Battle of France and more than one German cryptanalytic section proposed attempting to crack Typex; however, the B-Dienst codebreaking organisation gave up on it after six weeks, when further time and personnel for such attempts were refused.
One German cryptanalyst stated that the Typex was more secure than the Enigma since it had seven rotors, therefore no major effort was made to crack Typex messages as they believed that even the Enigma's messages were unbreakable.
Although the Typex has been attributed as having good security, the historic record is much less clear. There was an ongoing investigation into Typex security that arose out of German POWs in North Africa claiming that Typex traffic was decipherable.
A brief excerpt from the report
TOP SECRET U [ZIP/SAC/G.34]
THE POSSIBLE EXPLOITATION OF TYPEX BY THE GERMAN SIGINT SERVICES
The following is a summary of information so far received on German attempts to break into the British Typex machine, based on P/W interrogations carried out during and subsequent to the war. It is divided into (a) the North African interrogations, (b) information gathered after the end of the war, and (c) an attempt to sum up the evidence for and against the possibility of German successes.
Apart from an unconfirmed report from an agent in France on 19 July 1942 to the effect that the GAF were using two British machines captured at DUNKIRK for passing their own traffic between BERLIN and GOLDAP, our evidence during the war was based on reports that OKH was exploiting Typex material left behind in TOBRUK in 1942.
Typex machines continued in use long after World War II. The New Zealand military used TypeX machines until the early 1970s, disposing of its last machine in about 1973.
Advantages over Enigma
All the versions of the Typex had advantages over the German military versions of the Enigma machine. The German equivalent teleprinter machines in World War II (used by higher-level but not field units) were the Lorenz SZ 40/42 and Siemens and Halske T52 using Fish cyphers.
Most versions of the Enigma required two operators to operate effectively—one operator to input text into the Enigma and the other to copy down the enciphered or deciphered characters—Typex required just one operator.
Typex avoided operator copying errors, as the enciphered or deciphered text was automatically printed on paper tape.
Unlike Enigma, Typex I machines were linked to teleprinters while Typex II machines could be if required.
Enigma messages had to be written, enciphered, transmitted (by Morse), received, deciphered, and written again, while Typex messages were typed and automatically enciphered and transmitted all in one step, with the reverse also true.
See also
Cryptanalysis of the Enigma
Cryptanalysis of the Lorenz cipher
Mercury (Typex Mark X)—a Typex descendant used for on-line traffic.
Citations
General and cited references
Martin Campbell-Kelly, ICL: A Business and Technical History, Oxford University Press, 1990.
Dorothy Clarkson, "Cypher Machines: Maintenance and Restoration Spanning Sixty Years", Cryptologia, 27(3), July 2003, pp. 209–212.
Cipher A. Deavours and Louis Kruh, "Machine Cryptography and Modern Cryptanalysis", Artech House, 1985, pp. 144–145; 148–150.
Ralph Erskine, "The Admiralty and Cipher Machines During the Second World War: Not So Stupid after All". Journal of Intelligence History 2(2) (Winter 2002).
Ralph Erskine, "The Development of Typex", The Enigma Bulletin 2 (1997): pp. 69–86
Kruh and Deavours, "The Typex Cryptograph" Cryptologia 7(2), pp. 145–167, 1983
Eric Morgon, "The History of Communications Security in New Zealand", Part 1 (PDF).Possibly related page as html
External links
A series of photographs of a Typex Mk III
Jerry Proc's page on Typex
Typex graphical simulator for Microsoft Windows
Virtual Typex online simulator
Crypto Museum page on Typex
Cryptographic hardware
Rotor machines
World War II military equipment of the United Kingdom | Typex | Physics,Technology | 2,424 |
4,872,079 | https://en.wikipedia.org/wiki/Mesoridazine | Mesoridazine (Serentil) is a phenothiazine class drug that is used in the treatment of schizophrenia. It is one of the active metabolites of thioridazine. The drug's name is derived from the methylsulfoxy and piperidine functional groups in its chemical structure.
It has central antiadrenergic, antidopaminergic, antiserotonergic and weak muscarinic anticholinergic effects.
Serious side effects include akathisia, tardive dyskinesia and the potentially fatal neuroleptic malignant syndrome.
Mesoridazine was withdrawn from the United States market in 2004 due to dangerous side effects, namely irregular heart beat and QT-prolongation of the electrocardiogram.
Mesoridazine is on the FDA's Discontinued Drug Product List.
Synthesis
2-Methylthiophenothiazine [7643-08-5] (1) is treated with acetic anhydride] to give the protected amide, ie 10-acetyl-2-methylthiophenothiazine, CID:69367526. Oxidation of this by means of hydrogen peroxide and removal of the acetyl protecting group with potassium carbonate in methanol solution gives 2-methylsulfonylphenothiazine [23503-68-6] (3). Introduction of the sidechain by alkylation with 2-(2-chlorethyl)-1-methylpiperidine [50846-01-0] (6) in the presence of sodamide, afforded the desired mesoridazine (5).
References
M1 receptor antagonists
M2 receptor antagonists
M3 receptor antagonists
M4 receptor antagonists
M5 receptor antagonists
Phenothiazines
Piperidines
Sulfoxides
Tertiary amines
Typical antipsychotics
Withdrawn drugs | Mesoridazine | Chemistry | 397 |
12,172,142 | https://en.wikipedia.org/wiki/African%20grass%20rat | The African grass rat (Arvicanthis niloticus) is a species of rodent in the family Murinae.
Taxonomy
The species is divided into the following six subspecies.
A. n. niloticus: Nile, Egypt;
A. n. dembeensis (Rüppell, 1842): Sudan, Ethiopia, Eritrea; Tanzania, Kenya, Burundi, Uganda, Democratic Republic of Congo;
A. n. naso (Pocock, 1934): Yemen;
A. n. rhodesiae (St.Leger, 1932): Zambia;
A. n. solatus (Thomas, 1925): Senegal; Mauritania, Mali, Niger, Chad, Burkina Faso, Ghana, Nigeria, Cameroon and Central African Republic;
A. n. testicularis (Sundevall, 1843): upper Nile, central Sudan.
Description
Arvicanthis niloticus is a rodent of medium size, with the length of the head and of the body between 159 and 202 mm, the length of the tail between 125 and 173 mm, the length of the foot between 33 and 42 mm, the length of the ears between 19 and 23 mm and a weight up to 201 g.
The fur is rough. The upper parts of individual hairs are yellowish with blackish tips. Long yellow or orange hairs are present on the bottom. A dorsal dark stripe more or less distinct extends from the head to the base of the tail. The ventral parts are whitish, with the base of the hairs blackish.
Areas where there are the whiskers, the eyes and a small patch behind each ear are orange. The legs are pink. The tail is shorter than the head and body, densely covered with hair, blackish above and white-yellowish below. The karyotype is 2n = 62, FN = 62-64.
Distribution
It is mainly distributed in the Sahel and the sudano-zambesian Savanna belt, namely Benin, Burkina Faso, Burundi, Central African Republic, Chad, Democratic Republic of the Congo, Ivory Coast, Eritrea, Ethiopia, Gambia, Ghana, Kenya, Malawi, Mauritania, Niger, Nigeria, Senegal, Sierra Leone, Somalia, Sudan, Tanzania, Togo, Uganda, and Zambia. Populations also occur in Algeria, Egypt, and Yemen.
Cycle of life
Despite its wide distribution and commonness, little is known about the biology and actual occurrence of the species. It reproduces mainly between June and November. The females give birth to 5-6 small cubs at least 3-4 times a year. Life expectancy in the wild is 2.5–3 years.
Habitat
Its natural habitats are dry savanna, moist savanna, subtropical or tropical moist shrubland, arable land, pastureland, rural gardens, urban areas, irrigated land, and seasonally flooded agricultural land.
Use as an animal model for Type 2 Diabetes
The Nile rat has gained traction as a useful nutritional model to study Type 2 Diabetes (T2DM). The Nile Rat gets Metabolic Syndrome that develops into diet-induced Type 2 Diabetes that is similar to human T2DM: insulin resistance, hyperinsulinemia, increased body fat, hypertension, elevated Triglycerides with decreased High-Density Lipoproteins, and eventually hyperglycemia and beta cell failure resulting in depressed insulin and end-stage diabetes that includes severe ketosis. The beta cell failure follows the same course as the five-stage decline documented in humans with T2DM.
References
Arvicanthis
Rodents of Africa
Stored-product pests
Mammals described in 1803
Taxonomy articles created by Polbot | African grass rat | Biology | 730 |
26,613,492 | https://en.wikipedia.org/wiki/Egain%20forecasting | Egain forecasting is a method of controlling building heating by calculating demand for heating energy that should be supplied to the building in each time unit. By combining physics of structures with meteorology, properties of the building, weather conditions including outdoor temperature, wind speed and direction, as well as solar radiation can be taken into account. In the case of conventional heating control, only current outdoor temperature is considered.
The starting point for developing the method of eGain forecasting was the ENLOSS mathematical energy balance model developed by Prof. Roger Taesler
from Swedish Meteorological and Hydrological Institute in cooperation with Thorbjörn Geiser (member of the board) and Stefan Berglund, who are currently both employed at eGain Sweden AB. Forecasting method began to be introduced to use in the late 1980s.
Until 2017 inclusive, forecasting method has been introduced in nearly 16 million square metres of floorage of residential buildings and commercial premises. Estimated data indicate 10 - 15 kWh/m2 reduction of average annual heat energy consumption. Since forecasting method contains information about future demand and is not in conflict with other methods of increasing energy efficiency, it is always a good foreground solution.
eGain Forecasting in practice
As far as practical use of this forecasting method is concerned, remote control forecasting receivers are typically used to send and receive data by means of a GPRS or GSM network. The forecasting receivers then manage the operation of control panels installed in the buildings, which adjust distribution of heat energy in the heating system of a given property.
Recently, special remote control weather loggers have been introduced, and are used in combination with the forecasting receivers. The weather loggers accurately measure air temperature and humidity around the buildings, and these measurements are sent in real time to forecasting receivers. This turning point in technology provides an even more detailed analysis of the building and its environment, and thus improves the possibilities for control via this forecasting method.
Notes
References
Taesler, R. (1990/91) "Climate and Building Energy Management". Energy and Buildings, Vol. 15–16, pp. 599 – 608.
Sasic Kaligasidis, A et al. (2006) "Upgraded weather forecast control of building heating systems". pp. 951ff in Research in Building Physics and Building Engineering. Paul Fazio (Editorial Staff),
United States Patent 6098893 Comfort control system incorporating weather forecast data and a method for operating such a system (Inventor Stefan Berglund)
External links
eGain
Heat transfer
Weather forecasting
Sustainable technologies | Egain forecasting | Physics,Chemistry | 523 |
12,255,960 | https://en.wikipedia.org/wiki/Differential%20coefficient | In physics and mathematics, the differential coefficient of a function f(x) is what is now called its derivative df(x)/dx, the (not necessarily constant) multiplicative factor or coefficient of the differential dx in the differential df(x).
A coefficient is usually a constant quantity, but the differential coefficient of f is a constant function only if f is a linear function. When f is not linear, its differential coefficient is a function, call it , derived by the differentiation of f, hence, the modern term, derivative.
The older usage is now rarely seen.
Early editions of Silvanus P. Thompson's Calculus Made Easy use the older term. In his 1998 update of this text, Martin Gardner lets the first use of "differential coefficient" stand, along with Thompson's criticism of the term as a needlessly obscure phrase that should not intimidate students, and substitutes "derivative" for the remainder of the book.
References
Mathematical analysis
Differential calculus
Functions and mappings | Differential coefficient | Mathematics | 208 |
15,382,920 | https://en.wikipedia.org/wiki/Tripotassium%20phosphate | Tripotassium phosphate, also called tribasic potassium phosphate is a water-soluble salt with the chemical formula K3PO4.(H2O)x (x = 0, 3, 7, 9). Tripotassium phosphate is basic: a 1% aqueous solution has a pH of 11.8.
Production
Tripotassium phosphate is produced by the neutralization of phosphoric acid with potassium hydroxide:
Use in organic chemistry
Tripotassium phosphate has few industrial applications, however it is commonly used as a base in laboratory-scale organic chemistry. Being insoluble in organic solvents, it is an easily removed proton acceptor in organic synthesis. The anhydrous salt is especially basic. Some of the reactions are listed below:
The hydrate () has been used to catalyze the deprotection of BOC amines. Microwave radiation is used to aid the reaction.
As a catalyst for the synthesis of unsymmetrical diaryl ethers using [Bmim]BF4 as the solvent. Aryl methane-sulfonates are deprotected and then followed by a nucleophilic aromatic substitution (SNAr) with activated aryl halides.
As a base in the cross-coupling reaction of aryl halides with terminal alkynes. It also plays a role in the deacetonation of 4-aryl-2-methylbut-3-yn-2-ol intermediates.
As the base in the cross-coupling reaction between aryl halides and phenols or aliphatic alcohols.
Use in foods
Tripotassium phosphate can be used in foods as a buffering agent, emulsifying agent, and for nutrient fortification. It can serve as a sodium-free substitute for trisodium phosphate. The ingredient is most common in dry cereals but is also found in meat, sauces, and cheeses.
References
Potassium compounds
Phosphates
Food emulsifiers
E-number additives
Inorganic fertilizers
Deliquescent materials | Tripotassium phosphate | Chemistry | 428 |
38,282,497 | https://en.wikipedia.org/wiki/Gutmann%E2%80%93Beckett%20method | In chemistry, the Gutmann–Beckett method is an experimental procedure used by chemists to assess the Lewis acidity of molecular species. Triethylphosphine oxide (, TEPO) is used as a probe molecule and systems are evaluated by 31P-NMR spectroscopy. In 1975, used 31P-NMR spectroscopy to parameterize Lewis acidity of solvents by acceptor numbers (AN). In 1996, Michael A. Beckett recognised its more generally utility and adapted the procedure so that it could be easily applied to molecular species, when dissolved in weakly Lewis acidic solvents. The term Gutmann–Beckett method was first used in chemical literature in 2007.
Background
The 31P chemical shift (δ) of Et3PO is sensitive to chemical environment but can usually be found between +40 and +100 ppm. The O atom in Et3PO is a Lewis base, and its interaction with Lewis acid sites causes deshielding of the adjacent P atom. Gutmann, a chemist renowned for his work on non-aqueous solvents, described an acceptor-number scale for solvent Lewis acidity with two reference points relating to the 31P NMR chemical shift of Et3PO in the weakly Lewis acidic solvent hexane (δ = 41.0 ppm, AN 0) and in the strongly Lewis acidic solvent SbCl5 (δ = 86.1 ppm, AN 100). Acceptor numbers can be calculated from AN = 2.21 x (δsample – 41.0) and higher AN values indicate greater Lewis acidity. It is generally known that there is no one universal order of Lewis acid strengths (or Lewis base strengths) and that two parameters (or two properties) are needed (see HSAB theory and ECW model) to define acid and base strengths and that single parameter or property scales are limited to a smaller range of acids (or bases). The Gutmann-Beckett method is based on a single parameter NMR chemical shift scale but is in commonly used due to its experimental convenience.
Application to boranes
Boron trihalides are archetypal Lewis acids and have AN values between 89 (BF3) and 115 (BI3). The Gutmann–Beckett method has been applied to fluoroarylboranes such as B(C6F5)3 (AN 82), and borenium cations, and its application to these and various other boron compounds has been reviewed.
Application to other compounds
The Gutmann–Beckett method has been successfully applied to alkaline earth metal complexes, p-block main group compounds
(e.g. AlCl3, AN 87; silylium cations; [E(bipy)2]3+ (E = P, As, Sb, Bi) cations; cationic 4 coordinate Pv and Sbv derivatives) and transition-metal compounds (e.g. TiCl4, AN 70).
References
Acid–base chemistry
Nuclear magnetic resonance experiments | Gutmann–Beckett method | Chemistry | 612 |
622,034 | https://en.wikipedia.org/wiki/Connecting%20rod | A connecting rod, also called a 'con rod', is the part of a piston engine which connects the piston to the crankshaft. Together with the crank, the connecting rod converts the reciprocating motion of the piston into the rotation of the crankshaft. The connecting rod is required to transmit the compressive and tensile forces from the piston. In its most common form, in an internal combustion engine, it allows pivoting on the piston end and rotation on the shaft end.
The predecessor to the connecting rod is a mechanic linkage used by water mills to convert rotating motion of the water wheel into reciprocating motion.
The most common usage of connecting rods is in internal combustion engines or on steam engines.
Origins
A connecting rod crank has been found in the Celtic Oppida at Paule in Brittany, dated to 69BC
The predecessor to the connecting length is the mechanical linkage used by Roman-era watermills. An early example of this linkage has been found at the late 3rd century Hierapolis sawmill in Roman Asia (modern Turkey) and the 6th century saw mills at Ephesus in Asia Minor (modern Turkey) and at Gerasa in Roman Syria. The crank and connecting rod mechanism of these machines converted the rotary motion of the waterwheel into the linear movement of the saw blades.
An early documentation of the design occurred sometime between 1174 and 1206 AD in the Artuqid State (modern Turkey), when inventor Al-Jazari described a machine which incorporated the connecting rod with a crankshaft to pump water as part of a water-raising machine, though the device was more complex than typical crank and connecting rod designs. There is also documentation of cranks with connecting rods in the sketch books of Taccola from Renaissance Italy and 15th century painter Pisanello.
Steam engines
The 1712 Newcomen atmospheric engine (the first steam engine) used chain drive instead of a connecting rod, since the piston only produced force in one direction. However, most steam engines after this are double-acting, therefore the force is produced in both directions, leading to the use of a connecting rod. The typical arrangement uses a large sliding bearing block called a crosshead with the hinge between the piston and connecting rod placed outside the cylinder, requiring a seal around the piston rod.
In a steam locomotive, the cranks are usually mounted directly on the driving wheels. The connecting rod is used between the crank pin on the wheel and the crosshead (where it connects to the piston rod). On smaller steam locomotives, the connecting rods are usually of rectangular cross-section, however marine-type rods of circular cross-section have occasionally been used.
On paddle steamers, the connecting rods are called 'pitmans' (not to be mistaken for pitman arms).
Internal combustion engines
A connecting rod for an internal combustion engine consists of the 'big end', 'rod' and 'small end'. The small end attaches to the gudgeon pin (also called 'piston pin' or 'wrist pin' in the U.S.), which allows for rotation between the connecting rod and the piston. Typically, the big end connects to the crankpin using a plain bearing to reduce friction; however some smaller engines may instead use a rolling-element bearing, in order to avoid the need for a pumped lubrication system. Connecting rods with rolling element bearings are typically a one piece design where the crankshaft must be pressed together through them, rather than a two piece design that can be bolted around the journal of a one piece crankshaft.
Typically there is a pinhole bored through the bearing on the big end of the connecting rod so that lubricating oil squirts out onto the thrust side of the cylinder wall to lubricate the travel of the pistons and piston rings.
A connecting rod can rotate at both ends, so that the angle between the connecting rod and the piston can change as the rod moves up and down and rotates around the crankshaft.
Materials
The materials used for connecting rods widely vary, including carbon steel, iron base sintered metal, micro-alloyed steel, spheroidized graphite cast iron. In mass-produced automotive engines, the connecting rods are most usually made of steel. In high performance applications, "billet" connecting rods can be used, which are machined out of a solid billet of metal, rather than being cast or forged.
Other materials include T6-2024 aluminium alloy or T651-7075 aluminium alloy, which are used for lightness and the ability to absorb high impact at the expense of durability. Titanium is a more expensive option which reduces the weight. Cast iron can be used for cheaper, lower performance applications such as motor scooters.
Failure during operation
During each rotation of the crankshaft, a connecting rod is often subject to large and repetitive forces: shear forces due to the angle between the piston and the crankpin, compression forces as the piston moves downwards, and tensile forces as the piston moves upwards. These forces are proportional to the engine speed (RPM) squared.
Failure of a connecting rod, often called "throwing a rod", often forces the broken rod through the side of the crankcase and thereby renders the engine irreparable. Common causes of connecting rod failure are tensile failure from high engine speeds, the impact force when the piston hits a valve (due to a valvetrain problem), rod bearing failure (usually due to a lubrication problem), or incorrect installation of the connecting rod.
Cylinder wear
The sideways force exerted on the piston through the connecting rod by the crankshaft can cause the cylinders to wear into an oval shape. This significantly reduces engine performance, since the circular piston rings are unable to properly seal against the oval-shaped cylinder walls.
The amount of sideways force is proportional to the angle of the connecting rod, therefore longer connecting rods will reduce the amount of sideways force and engine wear. However, the maximum length of a connecting rod is constrained by the engine block size; the stroke length plus the connecting rod length must not result in the piston travelling past the top of the engine block.
Master-and-slave rods
Radial engines typically use master-and-slave connecting rods, whereby one piston (the uppermost piston in the animation), has a master rod with a direct attachment to the crankshaft. The remaining pistons pin their connecting rods' attachments to rings around the edge of the master rod.
Multi-bank engines with many cylinders, such as V12 engines, have little space available for many connecting rod journals on a limited length of crankshaft. The simplest solution, as used in most road car engines, is for each pair of cylinders to share a crank journal, but this reduces the size of the rod bearings and means that matching (i.e. opposite) cylinders in the different banks are slightly offset along the crankshaft axis (which creates a rocking couple). Another solution is to use master-and-slave connecting rods, where the master rod also includes one or more ring pins which are connected to the big ends of slave rods on other cylinders. A drawback of master-slave rods is that the stroke lengths of all slave pistons not located 180° from the master piston will always be slightly longer than that of the master piston, which increases vibration in V engines.
One of the most complicated examples of master-and-slave connecting rods is the 24-cylinder Junkers Jumo 222 experimental airplane engine developed for World War II. This engine consisted of six banks of cylinders, each with four cylinders per bank. Each "layer" of six cylinders used one master connecting rod, with the other five cylinders using slave rods. Approximately 300 test engines were built, however the engine did not reach production.
Fork-and-blade rods
Fork-and-blade rods, also known as "split big-end rods", have been used on V-twin motorcycle engines and V12 aircraft engines. For each pair of cylinders, a "fork" rod is split in two at the big end and the "blade" rod from the opposing cylinder is thinned to fit into this gap in the fork. This arrangement removes the rocking couple that is caused when cylinder pairs are offset along the crankshaft.
A common arrangement for the big-end bearing is for the fork rod to have a single wide bearing sleeve that spans the whole width of the rod, including the central gap. The blade rod then runs, not directly on the crankpin, but on the outside of this sleeve. This causes the two rods to oscillate back and forth (instead of rotating relative to each other), which reduces the forces on the bearing and the surface speed. However the bearing movement also becomes reciprocating rather than continuously rotating, which is a more difficult problem for lubrication.
Notable engines to use fork-and-blade rods include the Rolls-Royce Merlin V12 aircraft engine, EMD two-stroke Diesel engines, and various Harley Davidson V-twin motorcycle engines.
See also
Hydrolock
List of auto parts
Steam locomotive components
References
Engine technology
Locomotive parts
Linkages (mechanical) | Connecting rod | Technology | 1,860 |
67,545,702 | https://en.wikipedia.org/wiki/Exometeorology | Exometeorology is the study of atmospheric conditions of exoplanets and other non-stellar celestial bodies outside the Solar System, such as brown dwarfs. The diversity of possible sizes, compositions, and temperatures for exoplanets (and brown dwarfs) leads to a similar diversity of theorized atmospheric conditions. However, exoplanet detection technology has only recently developed enough to allow direct observation of exoplanet atmospheres, so there is currently very little observational data about meteorological variations in those atmospheres.
Observational and theoretical foundations
Modeling and theoretical foundations
Climate models have been used to study Earth's climate since the 1960s and other planets in our solar system since the 1990s. Once exoplanets were discovered, those same models were used to investigate the climates of planets such as Proxima Centauri b and the now-refuted Gliese 581g. These studies simulated what atmospheric pressures and compositions are necessary to maintain liquid water on each terrestrial exoplanet's surface, given their orbital distances and rotation periods. Climate models have also been used to study the possible atmospheres of the Hot Jupiter HD 209458b, the Hot Neptune GJ 1214b, and Kepler-1649b, a theorized Venus analog.
These models assume that the exoplanet in question has an atmosphere in order to determine its climate. Without an atmosphere, the only temperature variations on the planet's surface would be due to insolation from its star. Additionally, the main causes of weather - air pressure and air temperature differences which drive winds and the motion of air masses - can only exist in an environment with a significant atmosphere, as opposed to a tenuous and, consequently, rather static atmosphere, like that of Mercury. Thus, the existence of exometeorological weather (as opposed to space weather) on an exoplanet depends on whether it has an atmosphere at all.
Recent discoveries and observational foundations
The first exoplanet atmosphere ever observed was that of HD 209458b, a Hot Jupiter orbiting a G-type star similar in size and mass to our sun. Its atmosphere was discovered by spectroscopy; as the planet transited its star, its atmosphere absorbed some of the star's light according to the detectable absorption spectrum of sodium in the planet's atmosphere. While the presence of sodium was later refuted, that discovery paved the way for many other exoplanet atmospheres to be observed and measured. Recently, terrestrial exoplanets have had their atmospheres observed; in 2017, astronomers using a telescope at the European Southern Observatory (ESO) in Chile found an atmosphere on earth-sized exoplanet Gliese 1132 b.
However, measuring traditional meteorological variations in an exoplanet's atmosphere — such as precipitation or cloud coverage — is more difficult than observing just the atmosphere, due to the limited resolutions of current telescopes. That said, some exoplanets have shown atmospheric variations when observed at different times and other evidence of active weather. For example, an international team of astronomers in 2012 observed variations in hydrogen escape speeds from the atmosphere of HD 189733 b using the Hubble Space Telescope. Additionally, HD 189733 b and Tau Boötis Ab have their hottest surface temperatures displaced eastward from their subsolar points, which is only possible if those tidally-locked planets have strong winds displacing the heated air eastward, i.e. a westerly wind. Lastly, computer simulations of HD 80606b predict that the sudden increase in insolation it receives at periastron spawns shockwave-like windstorms that reverberate around the planet and distribute the sudden heat influx.
Theorized weather
Empirical observations of weather on exoplanets are still rudimentary, due to the limited resolutions of current telescopes. What little atmospheric variations can be observed usually relate to wind, such as variations in the escape speeds of atmospheric hydrogen in HD 189733b or just the speeds of globally circulating winds on that same planet. However, a number of other observable, non-meteorological properties of exoplanets factor into what exoweather is theorized to occur on their surfaces; some of these properties are listed below.
Presence of an atmosphere
As mentioned previously, exometeorology requires that an exoplanet has an atmosphere. Some exoplanets that do not currently have atmospheres began with one; however, these likely lost their primordial atmospheres due to atmospheric escape from stellar insolation and stellar flares or lost them due to giant impacts stripping the exoplanet's atmosphere.
Some exoplanets, specifically lava planets, might have partial atmospheres with unique meteorological patterns. Tidally-locked lava worlds receive so much stellar insolation that some molten crust vaporizes and forms an atmosphere on the day side of the planet. Strong winds attempt to carry this new atmosphere to the night side of the planet; however, the vaporized atmosphere cools as it nears the planet's night side and precipitates back down to the surface, essentially collapsing once it reaches the terminator. This effect has been modeled based on data from transits of K2-141b as well as CoRoT-7b, Kepler-10b, and 55 Cancri e. This unusual pattern of crustal evaporation, kilometer-per-second winds, and atmospheric collapse through precipitation might be provable with observations by advanced telescopes like Webb.
Exoplanets with full atmospheres are able to have diverse ranges of weather conditions, similar to weather on the terrestrial planets and gas giants of our Solar System. Planet-wide atmospheres allow for global air circulation, stellar thermal energy distribution, and relatively fast chemical cycling, as seen in the crustal material transportation by lava worlds' partial atmospheres and Earth's own water and carbon cycles. This ability to cycle and globally distribute matter and energy can drive iron rain on hot Jupiters, super-rotating winds on HD 189733b, and atmospheric precipitation and collapse on tidally-locked worlds.
Orbital properties
One of the most important factors determining an exoplanet's properties is its orbital period, or its average distance from its star. This alone determines a planet's effective temperature (the baseline temperature without added insulation from an atmosphere) and how likely the planet is to be tidally locked. These, in turn, can affect what chemical compositions of clouds can be present in a planet's atmosphere, the general motion of heat transfer and atmospheric circulation, and the locations where weather can occur (as with tidally-locked lava worlds with partial atmospheres).
For example, a gas giant's orbital period can determine whether its wind patterns are primarily advective (heat and air flowing from the top of the star-heated atmosphere to the bottom) or convective (heat and air flowing from down near the gradually contracting planet's core up through the atmosphere). If a gas giant's atmosphere receives more heat from insolation than the planet's unending gravitational contraction, then it will have advective circulation patterns; if the opposite heat source is stronger, it will have convective circulation patterns, as Jupiter exhibits.
Additionally, an exoplanet's average incident stellar radiation, determined by its orbital period, can determine what types of chemical cycling an exoplanet might have. Earth's water cycle occurs because our planet's average temperature is close enough to water's triple point (at normal atmospheric pressures) that the planet's surface can sustain three phases of the chemical; similar cycling is theorized for Titan, as its surface temperature and pressure is close to methane's triple point.
Similarly, an exoplanet's orbital eccentricity – how elliptical the planet's orbit is – can affect the incident stellar radiation it receives at different points in its orbit, and thus, can affect its meteorology. An extreme example of this is HD 80606b's shockwave-like storms that occur whenever the planet reaches the innermost point in its extremely eccentric orbit. The difference in distance between its apastron (analogous to Earth's aphelion) and its periastron (perihelion) is so large that the planet's effective temperature varies greatly throughout its orbit. A less extreme example is eccentricity in a terrestrial exoplanet's orbit. If the rocky planet orbits a dim red dwarf star, slight eccentricities can lead to effective temperature variations large enough to collapse the planet's atmosphere, given the right atmospheric compositions, temperatures, and pressures.
See also
Atmosphere and extraterrestrial atmosphere
Atmospheric circulation of exoplanets; the mathematical models governing exoplanetary air circulation
Atmospheric physics
References
Branches of meteorology
Atmosphere
Planetary science
Exoplanetology
Exoplanets
Astronomy | Exometeorology | Astronomy | 1,813 |
862,361 | https://en.wikipedia.org/wiki/H%C3%BCckel%27s%20rule | In organic chemistry, Hückel's rule predicts that a planar ring molecule will have aromatic properties if it has 4n + 2 π-electrons, where n is a non-negative integer. The quantum mechanical basis for its formulation was first worked out by physical chemist Erich Hückel in 1931. The succinct expression as the 4n + 2 rule has been attributed to W. v. E. Doering (1951), although several authors were using this form at around the same time.
In agreement with the Möbius–Hückel concept, a cyclic ring molecule follows Hückel's rule when the number of its π-electrons equals 4n + 2, although clearcut examples are really only established for values of n = 0 up to about n = 6. Hückel's rule was originally based on calculations using the Hückel method, although it can also be justified by considering a particle in a ring system, by the LCAO method and by the Pariser–Parr–Pople method.
Aromatic compounds are more stable than theoretically predicted using hydrogenation data of simple alkenes; the additional stability is due to the delocalized cloud of electrons, called resonance energy. Criteria for simple aromatics are:
the molecule must have 4n + 2 (a so-called "Hückel number") π electrons (2, 6, 10, ...) in a conjugated system of p orbitals (usually on sp2-hybridized atoms, but sometimes sp-hybridized);
the molecule must be (close to) planar (p orbitals must be roughly parallel and able to interact, implicit in the requirement for conjugation);
the molecule must be cyclic (as opposed to linear);
the molecule must have a continuous ring of p atomic orbitals (there cannot be any sp3 atoms in the ring, nor do exocyclic p orbitals count).
Monocyclic hydrocarbons
The rule can be used to understand the stability of completely conjugated monocyclic hydrocarbons (known as annulenes) as well as their cations and anions.
The best-known example is benzene (C6H6) with a conjugated system of six π electrons, which equals 4n + 2 for n = 1. The molecule undergoes substitution reactions which preserve the six π electron system rather than addition reactions which would destroy it. The stability of this π electron system is referred to as aromaticity. Still, in most cases, catalysts are necessary for substitution reactions to occur.
The cyclopentadienyl anion () with six π electrons is planar and readily generated from the unusually acidic cyclopentadiene (pKa 16), while the corresponding cation with four π electrons is destabilized, being harder to generate than a typical acyclic pentadienyl cations and is thought to be antiaromatic. Similarly, the tropylium cation (), also with six π electrons, is so stable compared to a typical carbocation that its salts can be crystallized from ethanol. On the other hand, in contrast to cyclopentadiene, cycloheptatriene is not particularly acidic (pKa 37) and the anion is considered nonaromatic. The cyclopropenyl cation () and the triboracyclopropenyl dianion () are considered examples of a two π electron system, which are stabilized relative to the open system, despite the angle strain imposed by the 60° bond angles.
Planar ring molecules with 4n π electrons do not obey Hückel's rule, and theory predicts that they are less stable and have triplet ground states with two unpaired electrons. In practice, such molecules distort from planar regular polygons. Cyclobutadiene (C4H4) with four π electrons is stable only at temperatures below 35 K and is rectangular rather than square. Cyclooctatetraene (C8H8) with eight π electrons has a nonplanar "tub" structure. However, the dianion (cyclooctatetraenide anion), with ten π electrons obeys the 4n + 2 rule for n = 2 and is planar, while the 1,4-dimethyl derivative of the dication, with six π electrons, is also believed to be planar and aromatic. The Cyclononatetraenide anion () is the largest all-cis monocyclic annulene/annulenyl system that is planar and aromatic. These bond angles (140°) differ significantly from the ideal angles of 120°. Larger rings possess trans bonds to avoid the increased angle strain. However, 10 to 14-membered systems all experience considerable transannular strain. Thus, these systems are either nonaromatic or experience modest aromaticity. This changes when we get to [18]annulene, with (4×4) + 2 = 18 π electrons, which is large enough to accommodate six interior hydrogen atoms in a planar configuration (3 cis double bonds and 6 trans double bonds). Thermodynamic stabilization, NMR chemical shifts, and nearly equal bond lengths all point to considerable aromaticity for [18]annulene.
The (4n+2) rule is a consequence of the degeneracy of the π orbitals in cyclic conjugated hydrocarbon molecules. As predicted by Hückel molecular orbital theory, the lowest π orbital in such molecules is non-degenerate and the higher orbitals form degenerate pairs. Benzene's lowest π orbital is non-degenerate and can hold 2 electrons, and its next 2 π orbitals form a degenerate pair which can hold 4 electrons. Its 6 π electrons therefore form a stable closed shell in a regular hexagonal molecule.
However for cyclobutadiene or cyclooctatrene with regular geometries, the highest molecular orbital pair is occupied by only 2 π electrons forming a less stable open shell. The molecules therefore stabilize by geometrical distortions which separate the degenerate orbital energies so that the last two electrons occupy the same orbital, but the molecule as a whole is less stable in the presence of such a distortion.
Heteroatoms
Hückel's rule can also be applied to molecules containing other atoms such as nitrogen or oxygen. For example, pyridine (C5H5N) has a ring structure similar to benzene, except that one -CH- group is replaced by a nitrogen atom with no hydrogen. There are still six π electrons and the pyridine molecule is also aromatic and known for its stability.
Polycyclic hydrocarbons
Hückel's rule is not valid for many compounds containing more than one ring. For example, pyrene and trans-bicalicene contain 16 conjugated electrons (8 bonds), and coronene contains 24 conjugated electrons (12 bonds). Both of these polycyclic molecules are aromatic, even though they fail the 4n + 2 rule. Indeed, Hückel's rule can only be theoretically justified for monocyclic systems.
Three-dimensional rule
In 2000, Andreas Hirsch and coworkers in Erlangen, Germany, formulated a rule to determine when a spherical compound will be aromatic. They found that closed-shell compounds were aromatic when they had 2(n + 1)2 π-electrons, for instance the buckminsterfullerene species C6010+.
In 2011, Jordi Poater and Miquel Solà expanded the rule to open-shell spherical compounds, finding they were aromatic when they had 2n2 + 2n + 1 π-electrons, with spin S = (n + 1/2) - corresponding to a half-filled last energy level with the same spin. For instance C601– is also observed to be aromatic with a spin of 11/2.
See also
Baird's rule (for triplet states)
References
Physical organic chemistry
Rules of thumb | Hückel's rule | Chemistry | 1,692 |
3,116,655 | https://en.wikipedia.org/wiki/Epsilon%20Corvi | Epsilon Corvi (ε Crv, ε Corvi) is a star in the southern constellation of Corvus. It has the traditional name Minkar , from Arabic منقار minqar meaning "beak [of the crow]" The apparent visual magnitude is +3.0 and it is located at a distance of from Earth.
In Chinese, (), meaning Chariot (asterism), refers to an asterism consisting of ε Corvi, γ Corvi, δ Corvi and β Corvi. Consequently, ε Corvi itself is known as (, .).
Epsilon Corvi is a red giant with a stellar classification of K2 III, having consumed the hydrogen at its core and evolved away from the main sequence. It has about three times the Sun's mass. The interferometry-measured angular diameter of this star is about 4.99 mas, which, at its estimated distance, equates to a physical radius of about 52 times the radius of the Sun. The effective temperature of the outer envelope is , giving it an orange hue that is characteristic of a K-type star. Around 4 times as massive as the Sun, it spent much of its life as a main sequence star of spectral type B5V.
References
Corvus (constellation)
Corvi, Epsilon
Minkar
Corvi, 02
059316
K-type giants
4630
105707
Durchmusterung objects | Epsilon Corvi | Astronomy | 307 |
20,776,375 | https://en.wikipedia.org/wiki/NGC%2035 | NGC 35 is a spiral galaxy in the constellation Cetus. It was discovered on November 21, 1886 by the astronomer Lewis A. Swift.
References
External links
Galaxies discovered in 1886
0035
000784
-02-01-033
Unbarred spiral galaxies
NGC 0035
18861121 | NGC 35 | Astronomy | 61 |
66,705,925 | https://en.wikipedia.org/wiki/Mary%20Ann%20Mansigh | Mary Ann Ruth Mansigh Karlsen (1932 – August 24, 2024) was an American computer programmer who was active in the 1950s in the use of scientific computers.
Biography
Mansigh attended the University of Minnesota on a scholarship from 1950 to 1954, where she studied physics, chemistry and mathematics. In 1955, she took a position at the Lawrence Livermore National Laboratory as a software engineer, where she would remain until she retired in 1994, working on over 13 generations of supercomputers from the UNIVAC (1955) to the Cray I (1994).
At the Lawrence Livermore National Laboratory, she worked with Berni Alder and Tom Wainwright in the implementation of molecular dynamics in the mid twentieth century, ultimately working exclusively with Alder for over twenty-five years. She is regarded as a pioneer in programming and computing, particularly molecular dynamics computing, whom Dutch computational physicist Daan Frenkel noted as being one of the very few notable female computer programmers, with Arianna W. Rosenbluth, that were active in the 1950s and 1960s.
Initially forgotten, except in annotations and oral transcripts, she has received increased attention in recent times, with events and talks on her legacy. In 2019, she had a lecture series at the Centre Européen de Calcul Atomique et Moléculaire (CECAM) named in her honour. Modern academics have noted her unfair absence as an author in published academic papers describing the results of computer programmes designed with her pioneering molecular dynamics computing code.
Mansigh died on August 24, 2024 at the age of 91.
See also
Mary Tsingou
References
External links
Computer Pioneer Mary Ann Mansigh Karlsen (Livermore Library and the American Association of University Women, March 2017)
Mary Ann Mansigh series: Almost famous, the woman behind the codes (Centre Européen de Calcul Atomique et Moléculaire (CECAM), May 2020)
Picture of Alder, Mansigh & Wainwright, in the Niels Bohr subssection of the AIP Emilio Segre Visual Archives. (University of Chicago)
Flowchart template (Object has "Mary Ann Mansigh" handwritten in red on lower edge) (Computer History Museum, Catalogue Number: 102678315)
1932 births
2024 deaths
Place of birth missing
Scientific computing researchers
American computer programmers
Nationality missing
American women computer scientists
American computer scientists
University of Minnesota College of Science and Engineering alumni
Lawrence Livermore National Laboratory staff
20th-century American women scientists | Mary Ann Mansigh | Technology | 505 |
18,732,880 | https://en.wikipedia.org/wiki/Storey | A storey (Commonwealth English) or story (American English; see spelling differences), is any level part of a building with a floor that could be used by people (for living, work, storage, recreation, etc.). Plurals for the word are storeys (UK, CAN) and stories (US).
The terms floor, level, or deck are used in similar ways (i.e. "the 16th floor"), but to refer to buildings it is more usual to speak of a "16-storey building". The floor at ground or street level is called the "ground floor" (i.e. it needs no number; the floor below it is called "basement", and the floor above it is called "first") in many regions. However, in some regions, like the US, ground floor is synonymous with first floor, leading to differing numberings of floors, depending on region – even between different national varieties of English.
The words storey and floor normally exclude levels of the building that are not covered by a roof, such as the terrace on the rooftops of many buildings. Nevertheless, a flat roof on a building is counted as a floor in other languages, for instance in Dutch, literally "roof-floor", simply counted one level up from the floor number that it covers.
A two-storey house or home extension is sometimes referred to as double-storey in the UK, while one storey is referred to as single-storey.
Overview
Houses commonly have only one or two floors, although three- and four-storey houses also exist. Buildings are often classified as low-rise, mid-rise and high-rise according to how many levels they contain, but these categories are not well-defined. A single-storey house is often referred to, particularly in the United Kingdom, as a bungalow. The tallest skyscraper in the world, the Burj Khalifa, also has the greatest number of storeys with 163.
The height of each storey is based on the ceiling height of the rooms plus the thickness of the floors between each pane. Generally this is around total; however, it varies widely from just under this figure to well over it. Storeys within a building need not be all the same height—often the lobby is taller, for example. One review of tall buildings suggests that residential towers may have 3.1 m (10 ft 2 in) floor height for apartments, while a commercial building may have floor height of 3.9 m (12 ft 9.5 in) for the storeys leased to tenants. In such tall buildings (60 or more storeys), there may be utility floors of greater height.
Additionally, higher levels may have less floor area than the ones beneath them (e.g., the Willis Tower).
In English the principal floor or main floor of a house is the floor that contains the chief apartments; it is usually the ground floor, or the floor above. In Italy the main floor of a home was traditionally above the ground level and was called the piano nobile ("noble floor").
The attic or loft is a storey just below the roof of the building; its ceiling is often pitched and/or at a different height from that of other floors. A penthouse is a luxury apartment on the topmost storey of a building. A basement is a storey below the main or ground floor; the first (or only) basement of a home is also called the lower ground floor.
Split-level homes have floors that are offset from each other by less than the height of a full storey. A mezzanine, in particular, is typically a floor halfway between two floors.
Numbering
Floor numbering is the numbering scheme used for a building's floors. There are two major schemes in use across the world. In the first system, used in such countries as the United States, Canada, China, Finland, Japan, Norway, Russia, and other ex-Soviet states, the number of floors is counted literally; that is, when one enters a building through the ground-level front door, one walks quite literally on the first floor; the storey above it therefore counts as the second floor. In the other system, used in the majority of European countries, floor at ground level is called the "ground floor", frequently having no number (or "0"); the next floor up is assigned the number 1 and is the first floor (first elevation), the first basement level gets '−1', and so on. In both systems, the numbering of higher floors continues sequentially as one goes up, as shown in the following table:
Consecutive number floor designations
Each scheme has further variations depending on how one refers to the ground floor and the subterranean levels. The existence of two incompatible conventions is a common source of confusion in international communication.
However, in all English-speaking countries, the storeys in a building are counted in the same way: a "seven-storey building" is unambiguous, although the top floor would be called "6th floor" in Britain and "7th floor" in America. This contrasts, for example, with French usage, where a 7-storey building is called une maison à 6 (six) étages. Mezzanines may or may not be counted as storeys.
European scheme
Floor at ground level
This convention can be traced back to Medieval European usage. In countries that use this system, the floor at ground level is usually referred to by a special name, usually translating as "ground floor" or equivalent. For example, ("ground floor") in Germany (sometimes however, , adopted from French), piano terra or (lit. "ground floor") in Italy, begane grond (lit. "trodden ground") in the Netherlands, planta baja (Castilian) or planta baixa (Catalan) in Spain (both meaning "bottom floor"), beheko solairua in Basque, andar térreo ("ground floor") in Brazil, rés-do-chão ("adjacent to the ground") in Portugal, ("ground level") in Hungary (although in Budapest the ("half floor", i.e. mezzanine) is an extra level between the ground and first floors, apparently a circumevention of construction regulations of the 19th and early 20th centuries), (from French street level, where rez is the old French of ras ("scraped"), ("street").) in France, parter in Poland and Romania, ("by the ground") in Slovakia, and ("close to the ground") in Slovenia. In some countries that use this scheme, the higher floors may be explicitly qualified as being above the ground level, such as in Slovenian prvo nadstropje (literally "first floor above ceiling (of the ground storey)").
First elevation, Europe, Latin America
In many countries in Europe, the second storey is called the "first floor", for being the first elevation. Besides Europe, this scheme is mostly used in some large Latin American countries (including Mexico, Argentina, Brazil, Paraguay, and Uruguay), and British Commonwealth nations (except Singapore and Canada).
First elevation, Spain
In Spain, the level above ground level (the mezzanine) is sometimes called ( in Catalan, etc., which literally means "interfloor"), and elevators may skip it. When the next level is different from the others, usually with higher ceiling and better decorations, then it is called principal (main floor). This is because before elevators the apartments in the floor that required less stairs to reach was the most expensive and usually also the most luxurious one. In those cases the "first floor" can therefore be two or three levels above ground level.
First elevation, Italy
In Italy, in the ancient palaces the first floor is called piano nobile ("noble floor"), since the noble owners of the palace lived there.
First elevation, France
In France, there are two distinct names for storeys at ground level, depending on whether it faces the street (called ,) or a garden (called ). Buildings which have two "ground floors" at different levels (on two opposite faces, usually) might have both.
First elevation, Croatia
The same differentiation is used as well in some buildings in Croatia. The lower level is called (abbr. RA), and the upper prizemlje (PR). If there is only one ground floor, it is called . The latter usage is standard for smaller buildings, such as single-family homes.
North American schemes
In the United States, the first floor and ground floor are usually equivalent, being at ground level, and may also be called the "lobby" or "main floor" to indicate the entrance to the building. The storey just above it is the second floor, and so on. The English-speaking parts of Canada generally follow the American convention, although Canada has kept the Commonwealth spelling "storey". In Quebec, the European scheme was formerly used (as in France), but by now it has been mostly replaced by the US system, so that rez-de-chaussée and premier étage ("first stage") are now generally equivalent in Quebec. Mexico, on the other hand, uses the European system.
The North American scheme is used in Finland, Norway, and Iceland. The Icelandic term ("ground floor") refers to the floor at ground level.
Latin America
European scheme: In many Latin American countries (including Argentina, Mexico, Paraguay, Uruguay and Venezuela) the ground floor is called planta baja and the next floor is primer piso. In Brazil the ground floor is called térreo and the next floor is primeiro andar.
In other countries, including Chile, Colombia, Ecuador and Peru, the ground floor is called primer piso (first floor). If planta baja is ever used it means the ground-level floor (although primer piso is used mainly for indoor areas, while planta baja is also used for areas outside the building).
East and Southeast Asian schemes
Most parts of East and Southeast Asia — including China (except for Hong Kong), Japan, Korea, and Singapore — follow the American system. Indonesia uses both the American and European systems. In the grammar of the respective languages, the numbers precede the word "floor", and are cardinals rather than ordinals, so they would translate literally as "1 floor (1F), 2 floor (2F)" (etc.), rather than "1st floor, 2nd floor", or "floor 1, floor 2".
Singapore
In Singapore, the British system of numbering originally prevailed. This was replaced in March 1983 with the North American scheme to create a simplified and consistent standard of numbering storeys. To emphasize the difference from the original scheme, reference is frequently made to storeys rather than floors, where the third (3rd) floor becomes either the fourth (4th) storey/level (storey/level 4). Many buildings continue to label storeys or levels rather than floors. However, in the absence of clear official distinction between the terms, the meaning of "floors" and "levels" have become interchangeable with "storey"; this is reflected in newer buildings. Some buildings in Singapore do use SL (Street Level) for ground level, while others such as Nex and West Coast Plaza uses the European scheme, albeit using "Basement 1" for ground level storey.
Vietnam
Vietnam uses both the North American and European schemes, generally depending on the region. In northern and central Vietnam, including the capital Hanoi, refers to any floor, including the ground floor, which is called . Meanwhile, in southern Vietnam, refers to the ground floor and refers to any floor above it, starting at directly above the ground floor.
A national standard, TCVN 6003-1:2012 (ISO 4157-1:1998), requires architectural drawings to follow the northern scheme. It also refers to a crawl space as . However, a given building's floor designations are unregulated. Thus, some apartment buildings in the largest city, Ho Chi Minh City, have posted floor numbers according to the northern scheme, while others label the ground floor as "G" or the thirteenth floor as "12 bis".
Idiosyncrasies
An extremely small number of American high-rise buildings follow the British/European system, often out of a desire on the part of the building's architect or owners.
An arrangement often found in high rise public housing blocks, particularly those built in the United Kingdom during the 1960s and 1970s, is that elevators would only call at half the total number of floors, or at an intermediate level between a pair of floors; for example an elevator of a 24-storey building would only stop at 12 levels, with staircases used to access the "upper" or "lower" level from each intermediate landing. This halves any building costs associated with elevator shaft doors. Where the total traffic necessitates a second elevator the alternate floors strategy is sometimes still applied, not only for the doorway reduction but also, provisionally upon the passengers preferring no particular floor beyond capacity, it tends toward halving the total delay imposed by the stops en route. Sometimes, two elevators are divided so that all floors are served, but one elevator only serves odd floors and the other even, which would often be less efficient for passengers, but cheaper to install because the group control of elevators was more complex than single control.
A few buildings in the United States and Canada have both a "first floor" (usually the main floor of the building) and a "ground floor" below it. This typically happens when both floors have street-level entrances, as is often the case for hillside buildings with walkout basements. In the UK, the lower of these floors would be called the "lower ground floor", while the upper would be called either the "upper ground floor" or simply the "ground floor". Multi-storey car parks which have a staggered arrangement of parking levels sometimes use a convention where there may be an "upper" and "lower" level of the same floor number, (e.g.: "1U/U1" = Upper 1st, "L2/2L" = "Lower 2nd" and so on), although the elevators will typically only serve one of the two levels, or the elevator lobby for each floor pair may be between the two levels.
In 19th-century London, many buildings were built with the main entrance floor a meter above ground, and the floor below that being two meters below ground. This was done partly for aesthetics, and partly to allow access between the lower level and the street without going through the main floor. In this situation, the lower level is called Lower Ground, the main floor is called Upper Ground, and floors above it are numbered serially from 1.
Sometimes, floor number 1 may be the lowest basement level; in that case the ground floor may be numbered 2 or higher. Sometimes two connected buildings (such as a store and its car park) have incongruent floor numberings, due to sloping terrain or different ceiling heights. To avoid this, shopping centers may call the main floors by names such as Upper Mall, Lower Mall, Lower Ground, with the parking floors being numbered Pn.
In some instances, buildings may omit the thirteenth floor in their floor numbering because of triskaidekaphobia, a common superstition surrounding this number. The floor numbering may either go straight from 12 to 14, or the floor may be given an alternative name such as "Skyline" or "14A". Due to a similar superstition in east Asia, some mainland Chinese, Taiwanese, and Indonesian buildings (typically high-rises) omit or skip the 4th floor along with other floor numbers ending in 4 such as 14 and 24. The floor above the third would be numbered as the fifth, and so on. This is because of tetraphobia: in many varieties of Chinese, the pronunciation of the word for "four" is very similar to the pronunciation of the word for "to die". Through Chinese cultural and linguistic influence, tetraphobia is common in many countries of East Asia. For this reason, apartments on the 4th floor in Asian countries such as Taiwan have traditionally been cheaper to rent.
In Hong Kong, the British numbering system is now generally used, in English and Chinese alike. In some older residential buildings, however, the floors are identified by signs in Chinese characters that say "" ("2 floor") at the floor just above ground, as in the North American system. For those buildings, the Chinese phrase "" or its English equivalent "3rd floor" may refer either to the storey three levels above ground (as in the modern numbering), which is actually labelled "" ("4 floor"), or to the storey with the sign "" ("3 floor"), which is only two levels above ground. This confusing state of affairs has led, for example, to numerous errors in utility billing. To avoid ambiguity, business forms often ask that storey numbers in address fields be written as accessed from an elevator. In colloquial speeches, the character "" maybe added before the number to emphasize it refers to the Chinese style of numbering, e.g. "" (literally "Chinese 3 floor"), or the character "" added after the number to refer to the British style of numbering as shown in an elevator, e.g. 2 (literally "2 digit floor", floor with number 2), while in writing in Chinese, Chinese numerals are used for Chinese style numbering, and Arabic numerals are used for British style numbering.
In Hawaii, the Hawaiian-language floor label uses the British system, but the English-language floor label uses the American system. For example, Papa akolu (P3) is equivalent to Level 4 (4 or L4).
In Greenland, the Greenlandic-language floor label uses the American system, but the Danish-language floor label uses the British system. Plan pingasut (P3) is equivalent to Level 2 (Plan to or P2).
Elevator buttons
In most of the world, elevator buttons for storeys above the ground level are usually marked with the corresponding numbers. In many countries, modern elevators also have Braille numbers—often mandated by law.
European scheme
In countries using the European system, the ground floor is either marked 0, or with the initial letter of the local word for ground floor (G, E, etc.), successive floors are then marked 1, 2, etc. However, even when the ground floor button is marked with a letter, some digital position indicators may show 0 when the elevator is on that floor. If the building also contains floors below ground, negative numbers are common. This then gives a conventional numbering sequence −2, −1, 0, 1, 2, 3, ... In Spain and other countries whose official language is Spanish or Portuguese, the ground floor is usually marked PB (planta baja, planta baixa, etc.), and in buildings where these exist, the entresuelo or entresòl and principal are marked E and P, respectively. In France, floors are usually marked the same way as in Spain; however, the letters for the ground floor are RDC (rez-de-chaussée), seldom simplified to RC. This scheme is also found in some buildings in Quebec. Where these exist, there are high ground RCH (rez-de-chaussée haut) and lower ground RCB (rez-de-chaussée bas), or garden ground RJ (rez-de-jardin) and former ground RC. In Portugal, the letters corresponding to the ground floor are R/C (rés-do-chão) or simply R.
For example, in the Polish language there is a clear distinction: the word means ground floor and means a floor above the parter, usually with an ordinal: 1st piętro, 2nd piętro etc. Therefore, a parter is the zeroth piętro. Older elevators in Poland have button marked P for the ground floor (parter) and S for basement (). Elevators installed since 1990 have 0 for parter and −1, −2 etc. for underground floors.
North American scheme
In countries using the North American system, where "floor 1" is the same as "ground floor", the corresponding button may be marked either with 1 or with a letter, as in the European scheme. In either case, the next button will be labelled 2. In buildings that have both a "1st floor" and a "ground floor", they may be labelled 1 and G, or M (for "Main") and LM (for "Lower Main"), the latter two being more common in Canada outside Quebec. M or MZ may also be used to designate a mezzanine level, when it is not counted as a separate floor in the building's numbering scheme. If an elevator has two doors, floors on one side might end up getting an R suffix for "rear", especially if on one floor both doors open.
In modern signage, at least in North America, a five-pointed star (★) additionally appears beside the button for the main entry floor. In the United States, the five-pointed-star marking is mandated by Title III of the Americans with Disabilities Act (ADA), as described in Section 4.10.12(2) of the ADA Accessibility Guidelines for Buildings and Facilities (ADAAG). However this may be used to simply indicate a way out, such as to indicate a sky lobby. As an example, the residential elevators at the John Hancock Center all have their main floors labeled as the 44th as in order to get from a residential floor to the ground one would need to take two elevators: one from the residences to the sky lobby, and the other from the sky lobby to the ground. In the event more than one floor could be considered main floor, such as when a building has exits on more than one floor, a relatively common solution is to simply have no star and have other indications to indicate a main floor. A less commonly used solution has more than one star.
Subterranean and split-level floors
There is no particular standard convention for the numbering of levels below ground. In English-speaking countries, the first level below ground may be labelled B for "Basement", LL for "Lower Level" or "Lower Lobby", C for "Cellar", or U for "Underground". In British buildings, LG for "Lower Ground" is commonly encountered.
If there is more than one basement, either the next level down may be marked SB for "Sub-Basement" or all lower levels can be numbered B1, B2, B3, Bn. Negative numbers are sometimes used, this being more common in Europe: −1 for the first level below ground, −2 for the second one, and so on. Letters are sometimes used: A, B, C, D, E, F, G, H, I, J, etc.
There can also be split-level parking levels with the lower one having the suffix "A" and the upper having the suffix "B", like "1A", "1B", "2A", "2B", etc. Elevators in split-level buildings normally stop at either the lower or upper level, and the levels in elevators may be named just "1", "2", etc.
Other labels
Elevator buttons may also be labelled according to their main function. In English-speaking countries, besides the common L for "Lobby", one may find P for "Platform" (in train stations), "Pool" or "Parking" (and P1, P2, P3, Pn for multiple parking floors), S for "Skyway" or "Street" (ST is also often used to indicate Street), C for "Casino" or "Concourse", R for "Restaurant" or Roof, PH for "Penthouse", OD for "observation deck", W for Walkway, T for Tunnel, Ticketing or Trains, etc. In some US buildings, the label G on the elevator may stand for the building's "Garage", which need not be located on the "Ground" floor. Sometimes GR might be used instead.
Fairmont Royal York Hotel in Toronto marks the first six floors as A, L, MM, C, H and 1 (for "Arcade", "Lobby", "Main Mezzanine", "Convention", "Health Club" and "1st floor"). The North Carolina Museum of Art, whose entrance is on the third floor up, has the floors lettered C, B, A (the main floor) and O (for "Office"). The Festival Walk mall in Hong Kong has floors labelled LG2 and LG1 ("Lower Ground 2" and "1"), G ("Ground") and UG ("Upper Ground"). In The Landmark Annex of TriNoma, DSn (n=floor) denotes the floor label of the department store area.
Room numbering
In modern buildings, especially large ones, room numbers are usually tied to the floor numbers, so that one can figure out the latter from the former. Typically one uses the floor number with one or two extra digits appended to identify the room within the floor. For example, room 215 could be the 15th room of floor 2 (or 5th room of floor 21), but to avoid this confusion one dot is sometimes used to separate the floor from the room (2.15 refers to 2nd floor, 15th room and 21.5 refers to 21st floor, 5th room) or a leading zero is placed before a single-digit room number (i.e. the 5th room of floor 21 would be 2105). Letters may be used, instead of digits, to identify the room within the floor—such as 21E instead of 215. Often odd numbers are used for rooms on one side of a hallway, even numbers for rooms on the other side.
An offset may be used to accommodate unnumbered floors. For example, in a building with floors labelled G, M, 1, 2, ..., 11 and 12, the fourth room in each of those floors could be numbered 1004, 1104, 1204, 1304, ..., 2204 and 2304, respectively—with an offset of 11 in the floor numbers. This trick is sometimes used to make the floor number slightly less obvious, e.g. for security or marketing reasons.
In some buildings with numbered rooms, UK-like G, 1, ... floor numbering is used, but with rooms numbered from 200 on the "first floor" (above the ground floor), 300 on the 2nd floor, and so on (which actually resembles US-like floor numbering).
Iberia
In Spain, Portugal and Andorra the rule (official standard) is:
In buildings with only two corridors, all the apartments are marked as Izq. or Esq. (Izquerdo, Esquerdo or Esquerre = Left) or Dcho. or Dto. (Derecho, Direito or Dret = Right). So we have Sótano Izq., C/V Esq. or Soterrani Esq. (Underground Floor Left), Bajo Izq., R/C Esq. or Baix Esq. (Ground Floor Left), 1º. Izq., 1º. Esq. or 1er Esq. (1st Floor Left), etc.; and Sótano Dcho., C/V Dto. or Soterrani Dret (Underground Floor Right), Bajo Dcho., R/C Dto. or Baix Dret (Ground Floor Right) 1º. Dcho., 1º. Dto. or 1er Dret (1st Floor Right), etc.
Buildings with more than two apartments per floor, are marked with letters, clockwise within each deck. So apartment 8º-D (not 8D) means the 8th floor (hence the character "º" designating an ordinal number), apartment D (counting in clockwise direction, for those who are in the floor entrance). But a very common form for buildings with three apartments per floor is, Esq.-Frt./Fte. (Frente, en: Front – for the apartment located between left and right)-Dto.
These universal rules simplify finding an apartment in a building, particularly for blind people, who do not need to ask where a given apartment is.
See also
Deck
Floor
List of buildings with 100 floors or more
Mechanical floor
Thirteenth floor
Explanatory notes
References
External links
Building
Identifiers
Floors | Storey | Engineering | 5,952 |
381,798 | https://en.wikipedia.org/wiki/Singleton%20%28mathematics%29 | In mathematics, a singleton (also known as a unit set or one-point set) is a set with exactly one element. For example, the set is a singleton whose single element is .
Properties
Within the framework of Zermelo–Fraenkel set theory, the axiom of regularity guarantees that no set is an element of itself. This implies that a singleton is necessarily distinct from the element it contains, thus 1 and are not the same thing, and the empty set is distinct from the set containing only the empty set. A set such as is a singleton as it contains a single element (which itself is a set, but not a singleton).
A set is a singleton if and only if its cardinality is . In von Neumann's set-theoretic construction of the natural numbers, the number 1 is defined as the singleton
In axiomatic set theory, the existence of singletons is a consequence of the axiom of pairing: for any set A, the axiom applied to A and A asserts the existence of which is the same as the singleton (since it contains A, and no other set, as an element).
If A is any set and S is any singleton, then there exists precisely one function from A to S, the function sending every element of A to the single element of S. Thus every singleton is a terminal object in the category of sets.
A singleton has the property that every function from it to any arbitrary set is injective. The only non-singleton set with this property is the empty set.
Every singleton set is an ultra prefilter. If is a set and then the upward of in which is the set is a principal ultrafilter on . Moreover, every principal ultrafilter on is necessarily of this form. The ultrafilter lemma implies that non-principal ultrafilters exist on every infinite set (these are called ).
Every net valued in a singleton subset of is an ultranet in
The Bell number integer sequence counts the number of partitions of a set (), if singletons are excluded then the numbers are smaller ().
In category theory
Structures built on singletons often serve as terminal objects or zero objects of various categories:
The statement above shows that the singleton sets are precisely the terminal objects in the category Set of sets. No other sets are terminal.
Any singleton admits a unique topological space structure (both subsets are open). These singleton topological spaces are terminal objects in the category of topological spaces and continuous functions. No other spaces are terminal in that category.
Any singleton admits a unique group structure (the unique element serving as identity element). These singleton groups are zero objects in the category of groups and group homomorphisms. No other groups are terminal in that category.
Definition by indicator functions
Let be a class defined by an indicator function
Then is called a singleton if and only if there is some such that for all
Definition in Principia Mathematica
The following definition was introduced by Whitehead and Russell
‘ Df.
The symbol ‘ denotes the singleton and denotes the class of objects identical with aka .
This occurs as a definition in the introduction, which, in places, simplifies the argument in the main text, where it occurs as proposition 51.01 (p. 357 ibid.).
The proposition is subsequently used to define the cardinal number 1 as
‘ Df.
That is, 1 is the class of singletons. This is definition 52.01 (p. 363 ibid.)
See also
References
Basic concepts in set theory
1 (number) | Singleton (mathematics) | Mathematics | 726 |
17,070,368 | https://en.wikipedia.org/wiki/Atomichron | The Atomichron was the world's first commercial atomic clock, built by the National Company, Inc. of Malden, Massachusetts. It was also the first self-contained portable atomic clock and was a caesium standard clock. More than 50 clocks with the trademarked Atomichron name were produced.
See also
Chip-scale atomic clock
Hoptroff London
References
External links
* A Brief History of the National Company, Inc
Atomichron: The Atomic Clock from Concept to Commercial Product
Atomichron NC-1001 Manual
Atomic clocks | Atomichron | Physics | 111 |
4,311,708 | https://en.wikipedia.org/wiki/NGC%207318 | NGC 7318 (also known as UGC 12099/UGC 12100 or HCG 92d/b) is a pair of colliding galaxies about 280 million light-years from Earth. They appear in the Constellation Pegasus and are members of Stephan's Quintet. They were discovered on 27 September 1873 by French astronomer Édouard Stephan.
The Spitzer Space Telescope revealed the presence of a large intergalactic shock wave, shown by an arc produced by NGC 7318b colliding with the group at ≥ 900 km/sec.
As NGC 7318b collides with NGC 7318a, atoms of hydrogen in the cluster's gas are heated by the shock wave, producing the green glow. The molecular hydrogen visible in the collision is one of the most turbulent forms known. This phenomenon was discovered by an international team of scientists of the Max Planck Institute for Nuclear Physics (MPIK) in Heidelberg. This collision can help provide a view into what happened in the early universe, around ten billion years ago.
See also
List of NGC objects (7001–7840)
References
External links
Hickson 92 in Pegasus
SIMBAD: VV 288 -- Interacting Galaxies
SIMBAD: UGC 12100—Interacting Galaxies
Barred spiral galaxies
Interacting galaxies
Elliptical galaxies
Peculiar galaxies
Stephan's Quintet
Pegasus (constellation)
7318
12099
069260
319
Discoveries by Édouard Stephan
Astronomical objects discovered in 1873
Galaxy mergers | NGC 7318 | Astronomy | 288 |
47,643,800 | https://en.wikipedia.org/wiki/Corallomycetella%20elegans | Corallomycetella elegans is one of the two recognized species in the fungus genus Corallomycetella. It is a parasite of rubber, cacao and tea trees.
See also
List of cacao diseases
List of tea diseases
References
External links
mycobank.org
Nectriaceae
Fungi described in 2013
Cacao diseases
Tea diseases
Fungal tree pathogens and diseases
Fungus species | Corallomycetella elegans | Biology | 79 |
2,582,187 | https://en.wikipedia.org/wiki/George%20Coyne | George Vincent Coyne, S.J. (January 19, 1933 – February 11, 2020) was an American Jesuit priest and astronomer who directed the Vatican Observatory and headed its research group at the University of Arizona from 1978 to 2020.
From January 2012 until his death, he taught at Le Moyne College in Syracuse, New York. His career was dedicated to the reconciliation of theology and science, while his stance on scripture was absolute: "One thing the Bible is not," he said in 1994, "is a scientific textbook. Scripture is made up of myth, of poetry, of history. But it is simply not teaching science."
Early years and education
George Coyne was born in Baltimore on January 19, 1933, the third of eight siblings. He entered the Jesuit novitiate in Wernersville, Pennsylvania, after attending Loyola High School in Blakefield, Maryland, on scholarship and graduating in 1951. He earned his bachelor's degree in mathematics and his licentiate in philosophy at Fordham University in 1958.
He carried out a spectrophotometric study of the lunar surface to obtain his doctorate in astronomy from Georgetown University in 1962. He spent the summer of 1963 doing research at Harvard University, the summer of 1964 as a National Science Foundation lecturer at the University of Scranton, and the summer of 1965 as visiting research professor at the University of Arizona Lunar and Planetary Laboratory (UA LPL). He obtained a licentiate in sacred theology at Woodstock College and was ordained a priest in 1966. Coyne was visiting assistant professor at the UA LPL in 1966-67 and 1968–69 and a visiting astronomer at the Vatican Observatory in 1967–68.
Director of Vatican Observatory
Coyne joined the Vatican Observatory as an astronomer in 1969 and became an assistant professor at the LPL in 1970. In 1976 he became a senior research fellow at the LPL and a lecturer in the UA Department of Astronomy. The following year he served as Director of the UA's Catalina Observatory and as associate director of the LPL. Pope John Paul I appointed him Director of the Vatican Observatory in 1978, and also associate director of the UA Steward Observatory. During 1979-80 he served as acting director and Head of the UA Steward Observatory and the Astronomy Department. He spent five months of the year in Tucson as adjunct professor in the University of Arizona Astronomy Department.
As Director of the Vatican Observatory he was a driving force in several new educational and research initiatives. He recruited young astronomers worldwide and established a program for non-resident adjunct appointments that allowed women to participate. Women accounted for almost half the participants in the biennial Vatican Observatory Summer School he established for astronomy graduate students. In the 1990s he organized conferences at the Observatory's headquarters in Castel Gandolfo, including one titled "God's Action in the Universe" sponsored jointly with the Center for Theology and the Natural Sciences of Berkeley, California. One of his successors said Coyne only asked his hires to do "good science" and that "He created a space where we were all free to pursue that science. He acted as a firewall between us and the vagaries of the Vatican. He made us welcome and he made our collaborators and visitors welcome."
In 2002, he co-authored with Alessandro Omizzolo, a priest-astronomer on the staff of the Observatory, Wayfarers in the Cosmos: The Human Quest for Meaning. He also took on a public role as an expert on the intersection of science and Catholicism. In 1994 he said that he was open to the existence of extraterrestrial life and that Christianity could reconcile its theology with such a discovery. He criticized the Church's lukewarm acceptance of responsibility for its prosecution of Galileo in the early seventeenth century.
Coyne was a vocal proponent of the view that a scientific view of evolution in its classic form, including its random nature, is compatible with Catholic teaching. In August 2005, he sharply critiqued an op-ed column in which Cardinal Christoph Schönborn appeared to question that position. He wrote that "If they respect the results of modern science, and indeed the best of modern biblical research, religious believers must move away from the notion of a dictator God or a designer God, a Newtonian God who made the universe as a watch that ticks along regularly.” He proposed an alternative view of God's role as creator: "God in his infinite freedom continuously creates a world that reflects that freedom at all levels of the evolutionary process to greater and greater complexity. He is not continually intervening, but rather allows, participates, loves." In November 2005, he said that "Intelligent design isn't science even though it pretends to be. If you want to teach it in schools, intelligent design should be taught when religion or cultural history is taught, not science."
From 2007 to 2011 Coyne directed the Vatican Observatory Foundation.
Scientific research
Coyne's research interests were in polarimetric studies of the interstellar medium, stars with extended atmospheres, and Seyfert galaxies, which are a class of spiral galaxies with very small and unusually bright star-like centers. Polarimetry studies can reveal the properties of cosmic dust and synchrotron radiation regions in galaxies and other astronomical objects. In later years he studied the polarization produced in cataclysmic variable stars, or interacting binary star systems that give off sudden bursts of intense energy, and dust about young stars. The asteroid 14429 Coyne is named for him.
Coyne was an active member of the International Astronomical Union, the American Astronomical Society, the Astronomical Society of the Pacific, the American Physical Society and the Optical Society of America.
In 1985, Coyne, along with Remo Ruffini (University of Rome "La Sapienza"), Riccardo Giacconi (Nobel Prize for Physics 2002), Abdus Salam (Nobel Prize for Physics 1979), Paul Boynton (University of Washington), Francis Everitt (Stanford University), Fang Li-Zhi (University of Science and Technology of China) founded the International Center for Relativistic Astrophysics (ICRA) in order to collaborate and exchange ideas among astrophysicists around the world.
Retirement
Coyne's tenure at the Vatican Observatory ended with the appointment of Argentine astronomer José Gabriel Funes to succeed him on August 19, 2006. Funes rejected tabloid speculation that Coyne's dispute with Schönborn had anything to do with his retirement. Coyne, then 73, said the idea was "simply not true".
In retirement, Coyne discussed that he did not, and other Christians should not, have problems reconciling his faith in Christ with contemporary scientific topics. In 2008, with Michael Heller, he co-authored Comprehensible Universe: The Interplay of Science and Theology.
Interviewed in the 2008 documentary film Religulous by political commentator Bill Maher, Coyne said that since all of the scriptures are written around/between 2000 BC and 200 AD, and modern science has only come into existence in the last couple of hundred years, the scriptures contain no science and should not be taught as science. He said:
In 2015 Coyne applauded Pope Francis for discussing the importance of caring for the environment and addressing the need for Christians to tackle the issue of climate change caused by human activity. He described Francis' encyclical Laudato Si' as "probably the most challenging encyclical since the great social encyclicals of Pope Leo XIII and Pope Pius XI in the 19th and early 20th centuries, which discussed the rights and duties of capital and labor". Coyne thought it "may very well provoke one of the most important dialogues between science and religion since the days of Charles Darwin".
Coyne died of bladder cancer on February 11, 2020, at a hospital in Syracuse at the age of 87.
Honors
Coyne received an honorary doctorate by Le Moyne College of Syracuse, New York, a Jesuit institution, on May 17, 2009, in recognition of "his tireless effort to promote an open dialogue between philosophy, theology, and the sciences" as part of his work "to bridge the gap between faith and science."
In 2008 Villanova University awarded Coyne the Mendel Medal, which recognizes outstanding scientists who have advanced the cause of science and demonstrated that between true science and true religion there is no intrinsic conflict.
In 2010 he was awarded the George Van Biesbroeck Prize by the American Astronomical Society.
Coyne received honorary degrees from St. Peter's University (1980), Loyola University Chicago (1994), the University of Padua (1995), the Pontifical Theological Academy of the Jagellonian University (1997), Marquette University (2005), and Boston College (2007).
Select writings
The Vatican Observatory Foundation hosts some of Coyne's writings and videos online.
Author
Co-author
See also
Evolution and the Roman Catholic Church
List of Jesuit scientists
List of Roman Catholic scientist-clerics
Notes
References
External links
audio and transcript
audio and transcript
1933 births
Writers from Baltimore
20th-century American astronomers
American Roman Catholic priests
Fordham University alumni
Georgetown University Graduate School of Arts & Sciences alumni
Harvard University staff
University of Scranton faculty
University of Arizona faculty
20th-century American Jesuits
21st-century American Jesuits
2020 deaths
Members of the Pontifical Academy of Sciences
Members of the International Society for Science and Religion
Scientists from Baltimore
Catholic clergy scientists
Vatican City scientists
Jesuit scientists
Woodstock College alumni
Theistic evolutionists
Deaths from bladder cancer in the United States
Deaths from cancer in New York (state)
21st-century American astronomers | George Coyne | Biology | 1,939 |
3,741,389 | https://en.wikipedia.org/wiki/Hylotheism | Hylotheism (from Gk. hyle, 'matter' and theos, 'God') is the belief that matter and God are the same, so in other words, defining God as matter.
The American Lutheran Church–Missouri Synod defines hylotheism is "Theory equating matter with God or merging one into the other" which it states as "Synonym for pantheism* and materialism.*".
See also
Pantheism
References
Lutheran theology
Conceptions of God
Matter
Lutheran Church – Missouri Synod | Hylotheism | Physics | 112 |
58,887,785 | https://en.wikipedia.org/wiki/Toehold%20mediated%20strand%20displacement | Toehold mediated strand displacement (TMSD) is an enzyme-free molecular tool to exchange one strand of DNA or RNA (output) with another strand (input). It is based on the hybridization of two complementary strands of DNA or RNA via Watson-Crick base pairing (A-T/U and C-G) and makes use of a process called branch migration. Although branch migration has been known to the scientific community since the 1970s, TMSD has not been introduced to the field of DNA nanotechnology until 2000 when Yurke et al. was the first who took advantage of TMSD. He used the technique to open and close a set of DNA tweezers made of two DNA helices using an auxiliary strand of DNA as fuel. Since its first use, the technique has been modified for the construction of autonomous molecular motors, catalytic amplifiers, reprogrammable DNA nanostructures and molecular logic gates. It has also been used in conjunction with RNA for the production of kinetically-controlled ribosensors. TMSD starts with a double-stranded DNA complex composed of the original strand and the protector strand. The original strand has an overhanging region the so-called “toehold” which is complementary to a third strand of DNA referred to as the “invading strand”. The invading strand is a sequence of single-stranded DNA (ssDNA) which is complementary to the original strand. The toehold regions initiate the process of TMSD by allowing the complementary invading strand to hybridize with the original strand, creating a DNA complex composed of three strands of DNA. This initial endothermic step is rate limiting and can be tuned by varying the strength (length and sequence composition e.g. G-C or A-T rich strands) of the toehold region. The ability to tune the rate of strand displacement over a range of 6 orders of magnitude generates the backbone of this technique and allows the kinetic control of DNA or RNA devices.
After the binding of the invading strand and the original strand occurred, branch migration of the invading domain then allows the displacement of the initial hybridized strand (protector strand). The protector strand can possess its own unique toehold and can, therefore, turn into an invading strand itself, starting a strand-displacement cascade. The whole process is energetically favored and although a reverse reaction can occur its rate is up to 6 orders of magnitude slower.
Additional control over the system of toehold mediated strand displacement can be introduced by toehold sequestering.
A slightly different variant of strand displacement has also been introduced using a strand displacing polymerase enzyme. Unlike TMSD, it used the polymerase enzyme as a source of energy and it referred to as polymerase-based strand displacement.
Toehold sequestering
Toehold sequestering is a technique to “mask” the toehold region, rendering its accessibility. There are several ways to do so but the most common approaches are hybridizing the toehold with a complementary strand or by designing the toehold region to form a hairpin loop. Masking and unmasking of the toehold domains together with the ability to precisely control the kinetics of the reaction makes toehold mediated strand displacement a valuable tool in the field of DNA nanotechnology Moreover, biosensors based on toehold mediated strand displacement reaction are useful in single molecule detection of DNA targets and SNP discrimination.
References
Genetic engineering | Toehold mediated strand displacement | Chemistry,Engineering,Biology | 701 |
7,378,996 | https://en.wikipedia.org/wiki/Phlebopus%20marginatus | Phlebopus marginatus, commonly known as the salmon gum mushroom in Western Australia, is a member of the Boletales or pored fungi. An imposing sight in forests of south-eastern and south-western Australia, it is possibly Australia's largest terrestrial mushroom, with the weight of one specimen from Victoria recorded at . Initially described in 1845 as Boletus marginatus, and also previously known by scientific names such as Phaeogyroporus portentosus and Boletus portentosus, it is not as closely related to typical boletes as previously thought.
Taxonomy
English naturalist Miles Joseph Berkeley initially described Boletus marginatus in 1845, from the writings and specimens of James Drummond, from the vicinity of the Swan River Colony in Western Australia. Berkeley and Broome described Boletus portentosus in a report published in 1873 of the fungi of Ceylon, from a specimen with a 25 cm (8 in) diameter cap collected on June 15, 1869. They held it to be related to Boletus aestivalis. Microscopic differences led to it being reclassified; Boedijn noted the shape of its spores, lack of cystidia and short tubes and allocated it to the genus Phlebopus in 1951. New Zealand botanist Robert McNabb followed Rolf Singer who had determined Phlebopus was a nomen dubium (though conceding Singer was likely in error), and coined the binomial Phaeogyroporus portentosus, by which it was known for some years. In his 1982 review of the genus, mycologist Paul Heinemann used this latter designation. The generic name is derived from the Greek Φλεψ/Φλεβο- "vein", and πους "foot".
Considering the two taxa to be the same, mycologist Roy Watling proposed the name Phlebopus marginatus over P. portentosus in 2001, pointing out that the former name predated the latter. He noted specimens across its range conform to the species description, although queried whether a single species occurs over so wide a range.
It is not as closely related to typical boletes as was previously thought. The genus Phlebopus is a member of the suborder Sclerodermatineae, which makes it more closely related to earth balls than to typical boletes. Within this suborder, Phlebopus makes up the family Boletinellaceae with Boletinellus. Boletus brevitubus, described from Cephalocitrus grandis and Delonix regia forests of Yunnan, China in 1991, was placed into synonymy with Phlebopus marginatus in 2009.
A common name in Western Australia is salmon gum mushroom. Common names in Asia include hed har and hed tub tao dum in Thailand, or tropical black bolete.
Description
Possibly Australia's largest terrestrial mushroom, Phlebopus marginatus produces fruit bodies that can reach huge proportions. The weight of one specimen from western Victoria recorded at 29 kg (64 pounds). John Burton Cleland reported finding specimens with a cap diameter of , weighing over , but reports about specimens with caps over in diameter also exist. The cap is convex to flat, occasionally with a depressed centre. It is brown to olive and covered in fine hair. Records between countries vary as to the colour change on cutting or bruising of flesh, with those of Western Australia indicating no change, while New Zealand and Indonesian collections are reported to have some bluish discoloration on bruising at the top of the stem. The spores are yellow-brown. Mature specimens are very attractive to insects and often infested with them.
Distribution and habitat
Phlebopus marginatus is an example of a Gondwanan fungus, being found in Indonesia, Malaysia and Sri Lanka as well as Australia and New Zealand, with related species found in South America. In fact, it is a pantropical species.
Within Australia it has been recorded from the southeast of South Australia to New South Wales. Within Australia it occurs in eucalypt forests and may be found any time after rain. Fruit bodies may be isolated or spring up in groups or even fairy rings. It occurs in rainforest in the Cooloola section of the Great Sandy National Park in Queensland.
In New Zealand it is possibly associated with Nothofagus truncata. McNabb was unsure of whether it was introduced or indigenous to New Zealand though suspected it was the latter due to it being found in dense native forest near Rotorua. Other collections were in the vicinity of Auckland.
It is common in Java and Sumatra.
In China it is found in Yunnan, Guangxi and Hainan provinces. In China, it grows in association with poinciana (Delonix regia), mango (Mangifera indica), coffee (Coffea arabica), pomelo (Citrus grandis), jackfruit (Artocarpus heterophyllus) and oak (Quercus) species.
Edibility
As with many Australian mushrooms, Phlebopus marginatus is not widely eaten although recorded in several publications as edible and mild tasting or bland. Australian mushroom expert Bruce Fuhrer warns of its propensity to be maggot-ridden.
It is consumed in Laos, northern Thailand, Myanmar and southern China, namely the tropical areas of Yunnan province, where excessive picking for markets has depleted wild populations. Its large size and flavour make it a desired mushroom in markets in the Xishuangbanna region.
It is also consumed on the island of Réunion.
Since 2003, efforts have been made to try and cultivate it.
References
Cited texts
External links
Australia's Gondwanan and Asian connections - Fungi
IMC8 Fungus of the Month - July 2004, Phlebopus marginatus
Boletales
Fungi of Asia
Fungi native to Australia
Fungi of New Zealand
Fungi found in fairy rings
Taxa named by Roy Watling
Fungus species | Phlebopus marginatus | Biology | 1,231 |
33,513,998 | https://en.wikipedia.org/wiki/TalkBox%20Voice%20Messenger | Talkbox Messenger (formerly named TalkBox and Talkbox Voice Messenger) is a smartphone application that enables users of iPhone, Android, Windows Phone and BlackBerry to easily communicate via push-to-talk instant voice messages as well as sharing geo-location, pictures and group chat with one another. Users’ voice is carefully curated and delivered by Talkbox voice bubbles of maximum 1 minute. Talkbox also integrated with different social networking elements which enables users to post voice post using Agent Twitter or Agent Facebook. It can also be applied to different business scenario from talking to an oversea business acquaintance without having to schedule an appointment to brainstorming a new product ideas with the team using group chat.
Talkbox acquired one million users within one month of initial release.
On Feb 1,2019, the app was renamed as Talkbox Messenger, with release of version 3.0.
References
External links
TalkBox Official website
Android (operating system) software
IOS software
Instant messaging clients
Cross-platform software | TalkBox Voice Messenger | Technology | 197 |
46,814,283 | https://en.wikipedia.org/wiki/List%20of%20abstractions%20%28computer%20science%29 | 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
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.
Data Structures
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).
Functional Programming Abstractions
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
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
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
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
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.
Notes
References
Textbook reference:
Keller, Robert M. Computer Science: Abstraction to Implementation. Harvey Mudd College, September 2001.
Computer science
Abstraction
Programming language concepts | List of abstractions (computer science) | Technology | 679 |
508,664 | https://en.wikipedia.org/wiki/Exergonic%20reaction | In chemical thermodynamics, an exergonic reaction is a chemical reaction where the change in the free energy is negative (there is a net release of free energy). This indicates a spontaneous reaction if the system is closed and initial and final temperatures are the same. For processes that take place in a closed system at constant pressure and temperature, the Gibbs free energy is used, whereas the Helmholtz energy is relevant for processes that take place at constant volume and temperature. Any reaction occurring at constant temperature without input of electrical or photon energy is exergonic, according to the second law of thermodynamics. An example is cellular respiration.
Symbolically, the release of free energy, , in an exergonic reaction (at constant pressure and temperature) is denoted as
Although exergonic reactions are said to occur spontaneously, this does not imply that the reaction will take place at an observable rate. For instance, the disproportionation of hydrogen peroxide releases free energy but is very slow in the absence of a suitable catalyst. It has been suggested that eager would be a more intuitive term in this context.
More generally, the terms exergonic and endergonic relate to the free energy change in any process, not just chemical reactions. By contrast, the terms exothermic and endothermic relate to an enthalpy change in a closed system during a process, usually associated with the exchange of heat.
See also
Endergonic reaction
References
Thermochemistry
Thermodynamic processes | Exergonic reaction | Physics,Chemistry | 324 |
30,443,289 | https://en.wikipedia.org/wiki/ITU%20Telecom%20World | ITU Telecom is part of the ITU (International Telecommunication Union), the United Nations specialized agency for information and communication technologies – ICTs. ITU Telecom organizes the global ITU Telecom World event, the platform for innovation showcasing, high-level debate, knowledge sharing and networking for the governments, industry leaders, small and medium enterprises (SMEs) and regulators that form part of the world's ICT community. The first ITU Telecom event was held in 1971. Since its fortieth anniversary in 2011, ITU Telecom World has been held on an annual basis in a different location worldwide. 2020's event will be ITU Digital World, taking place online from 20–22 October. ITU Digital World 2021 will be back in its usual form in Ha Noi Viet Nam in October 2021.
History
In 1985, the ITU Telecom staged its first regional telecommunication exhibition in the Asia-Pacific region – Asia Telecom85. This was followed the next year by its first regional event in the Africa region – Africa Telecom86. Regional telecommunication exhibitions continued with the first such events in the Americas region – Americas Telecom 88 and in the Europe region - Europa Telecom 1992. Telecom events were held on a regional or global basis every year, adopting the ITU Telecom World name for the first time at the Geneva event in 2003. The final event to be held in this format was ITU Telecom World 2009 which was attended by over 2,250 VIPs, including UN Secretary-General Ban Ki-moon, Heads of State, Heads of Government, Ministers, Ambassadors, heads of regulatory agencies, and CEOs from around the world. Through a series of top-level roundtables, meetings and debates, the event addressed pressing issues such as climate change, global economic recovery and cybersecurity.
Marking the 40th anniversary of the event, ITU Telecom World 2011 introduced a new format focused on facilitating knowledge sharing, networking, deal-making and consensus.building, with 6500 industry professionals taking part. ITU Telecom World 2012 took place in Dubai, where it was hosted by the UAE Telecommunications Regulatory Authority. The event moved to Bangkok, Thailand, for ITU Telecom World 2013, and to Doha, Qatar, for ITU Telecom World 2014.
ITU Telecom World 2015
ITU Telecom World 2015 took place from 12–15 October 2015 in Budapest, Hungary.
ITU Telecom World 2016
ITU Telecom World 2016 took place from 14–17 November in Bangkok, Thailand, on the central theme of Collaborating in the Digital Economy.
ITU Telecom World 2017
ITU Telecom World 2017 took place in the city of Busan, Republic of Korea, from 25–28 September 2017.
ITU Telecom World 2018
ITU Telecom World 2018 took place in Durban, South Africa from 10–13 September 2018
ITU Telecom World 2019
ITU Telecom World 2019 took place in Budapest, Hungary from 9–12 September 2019
Past events
Telecom 71 (Geneva)
Telecom 75 (Geneva)
Telecom 79 (Geneva)
Telecom 83 (Geneva)
Asia Telecom 1985 (Singapore)
Africa Telecom 1986 (Nairobi)
Telecom 87 (Geneva)
Americas Telecom 1988 (Rio)
Asia Telecom 1989 (Singapore)
Africa Telecom 1990 (Harare)
Telecom 91(Geneva)
Europa Telecom 1992 (Budapest)
Americas Telecom 1992 (Acapulco)
Asia Telecom 1993 (Singapore)
Africa Telecom 1994 (Cairo)
Telecom 95 (Geneva)
Americas Telecom 1996 (Rio)
Interactive 97(Geneva)
Asia Telecom 1997 (Singapore)
Africa Telecom 1998 (Johannesburg)
Telecom 99 (Geneva)
ITU Telecom Asia 2000 (Hong Kong)
ITU Telecom Americas 2000 (Rio)
ITU Telecom Africa 2001 (Johannesburg)
ITU Telecom Asia 2002 (Hong Kong)
ITU Telecom Americas 2003 (Buenos Aires)
ITU Telecom World 2003 (Geneva)
ITU Telecom Africa 2004 (Cairo)
ITU Telecom Asia 2004 (Busan)
ITU Telecom Americas 2005 (Bahia)
ITU Telecom World 2006 (Hong Kong)
ITU Telecom Asia 2008 (Bangkok)
ITU Telecom Africa 2008 (Cairo)
ITU Telecom World 2009 (Geneva)
ITU Telecom World 2011 (Geneva)
ITU Telecom World 2012 (Dubai)
ITU Telecom World 2013 (Bangkok)
ITU Telecom World 2014 (Doha)
ITU Telecom World 2015 (Budapest)
ITU Telecom World 2016 (Bangkok)
ITU Telecom World 2017 (Busan, Republic of Korea)
ITU Telecom World 2018 (Durban)
ITU Telecom World 2019 (Budapest)
References
International Telecommunication Union
Wireless
Technology conferences
Recurring events established in 1971
1971 establishments in Switzerland | ITU Telecom World | Engineering | 909 |
3,568,695 | https://en.wikipedia.org/wiki/Torsion%20group | In group theory, a branch of mathematics, a torsion group or a periodic group is a group in which every element has finite order. The exponent of such a group, if it exists, is the least common multiple of the orders of the elements.
For example, it follows from Lagrange's theorem that every finite group is periodic and it has an exponent that divides its order.
Infinite examples
Examples of infinite periodic groups include the additive group of the ring of polynomials over a finite field, and the quotient group of the rationals by the integers, as well as their direct summands, the Prüfer groups. Another example is the direct sum of all dihedral groups. None of these examples has a finite generating set. Explicit examples of finitely generated infinite periodic groups were constructed by Golod, based on joint work with Shafarevich (see Golod–Shafarevich theorem), and by Aleshin and Grigorchuk using automata. These groups have infinite exponent; examples with finite exponent are given for instance by Tarski monster groups constructed by Olshanskii.
Burnside's problem
Burnside's problem is a classical question that deals with the relationship between periodic groups and finite groups, when only finitely generated groups are considered: Does specifying an exponent force finiteness? The existence of infinite, finitely generated periodic groups as in the previous paragraph shows that the answer is "no" for an arbitrary exponent. Though much more is known about which exponents can occur for infinite finitely generated groups there are still some for which the problem is open.
For some classes of groups, for instance linear groups, the answer to Burnside's problem restricted to the class is positive.
Mathematical logic
An interesting property of periodic groups is that the definition cannot be formalized in terms of first-order logic. This is because doing so would require an axiom of the form
which contains an infinite disjunction and is therefore inadmissible: first order logic permits quantifiers over one type and cannot capture properties or subsets of that type. It is also not possible to get around this infinite disjunction by using an infinite set of axioms: the compactness theorem implies that no set of first-order formulae can characterize the periodic groups.
Related notions
The torsion subgroup of an abelian group A is the subgroup of A that consists of all elements that have finite order. A torsion abelian group is an abelian group in which every element has finite order. A torsion-free abelian group is an abelian group in which the identity element is the only element with finite order.
See also
Torsion (algebra)
Jordan–Schur theorem
References
R. I. Grigorchuk, Degrees of growth of finitely generated groups and the theory of invariant means, Izv. Akad. Nauk SSSR Ser. Mat. 48:5 (1984), 939–985 (Russian).
Properties of groups | Torsion group | Mathematics | 623 |
12,179,236 | https://en.wikipedia.org/wiki/Periplanone%20B | Periplanone B is a pheromone produced by the female American cockroach, Periplaneta americana. It is a sexual attractant to male cockroaches, especially at short ranges.
History
The activity of this pheromone was first described in 1952, but it was not until 25 years later that Persoons et al. reported the gross structure of periplanones A and B. The stereochemical configuration and first total synthesis were reported by W. Clark Still's group at Columbia University in 1979.
References
Insect pheromones
Epoxides
Sesquiterpenes
Spiro compounds
Ketones
Dienes
Oxygen heterocycles
Vinylidene compounds | Periplanone B | Chemistry | 144 |
22,819,753 | https://en.wikipedia.org/wiki/Acaulospora%20lacunosa | Acaulospora lacunosa is a species of fungus in the family Acaulosporaceae. It forms arbuscular mycorrhiza and vesicles in roots. Originally found in West Virginia in soil associated with Andropogon virginicus, the fungus was described as new to science in 1986. The specific epithet refers to the outermost wall of the spore, which has a characteristic appearance of the lunar surface.
References
Diversisporales
Fungi described in 1986
Fungi of West Virginia
1986 in West Virginia
Fungi without expected TNC conservation status
Fungus species | Acaulospora lacunosa | Biology | 117 |
847,810 | https://en.wikipedia.org/wiki/Dynamic%20dispatch | In computer science, dynamic dispatch is the process of selecting which implementation of a polymorphic operation (method or function) to call at run time. It is commonly employed in, and considered a prime characteristic of, object-oriented programming (OOP) languages and systems.
Object-oriented systems model a problem as a set of interacting objects that enact operations referred to by name. Polymorphism is the phenomenon wherein somewhat interchangeable objects each expose an operation of the same name but possibly differing in behavior. As an example, a object and a object both have a method that can be used to write a personnel record to storage. Their implementations differ. A program holds a reference to an object which may be either a object or a object. Which it is may have been determined by a run-time setting, and at this stage, the program may not know or care which. When the program calls on the object, something needs to choose which behavior gets enacted. If one thinks of OOP as sending messages to objects, then in this example the program sends a message to an object of unknown type, leaving it to the run-time support system to dispatch the message to the right object. The object enacts whichever behavior it implements.
Dynamic dispatch contrasts with static dispatch, in which the implementation of a polymorphic operation is selected at compile time. The purpose of dynamic dispatch is to defer the selection of an appropriate implementation until the run time type of a parameter (or multiple parameters) is known.
Dynamic dispatch is different from late binding (also known as dynamic binding). Name binding associates a name with an operation. A polymorphic operation has several implementations, all associated with the same name. Bindings can be made at compile time or (with late binding) at run time. With dynamic dispatch, one particular implementation of an operation is chosen at run time. While dynamic dispatch does not imply late binding, late binding does imply dynamic dispatch, since the implementation of a late-bound operation is not known until run time.
Single and multiple dispatch
The choice of which version of a method to call may be based either on a single object, or on a combination of objects. The former is called single dispatch and is directly supported by common object-oriented languages such as Smalltalk, C++, Java, C#, Objective-C, Swift, JavaScript, and Python. In these and similar languages, one may call a method for division with syntax that resembles
dividend.divide(divisor) # dividend / divisor
where the parameters are optional. This is thought of as sending a message named with parameter to . An implementation will be chosen based only on 's type (perhaps rational, floating point, matrix), disregarding the type or value of .
By contrast, some languages dispatch methods or functions based on the combination of operands; in the division case, the types of the and together determine which operation will be performed. This is known as multiple dispatch. Examples of languages that support multiple dispatch are Common Lisp, Dylan, and Julia.
Dynamic dispatch mechanisms
A language may be implemented with different dynamic dispatch mechanisms. The choices of the dynamic dispatch mechanism offered by a language to a large extent alter the programming paradigms that are available or are most natural to use within a given language.
Normally, in a typed language, the dispatch mechanism will be performed based on the type of the arguments (most commonly based on the type of the receiver of a message). Languages with weak or no typing systems often carry a dispatch table as part of the object data for each object. This allows instance behaviour as each instance may map a given message to a separate method.
Some languages offer a hybrid approach.
Dynamic dispatch will always incur an overhead so some languages offer static dispatch for particular methods.
C++ implementation
C++ uses early binding and offers both dynamic and static dispatch. The default form of dispatch is static. To get dynamic dispatch the programmer must declare a method as .
C++ compilers typically implement dynamic dispatch with a data structure called a virtual function table (vtable) that defines the name-to-implementation mapping for a given class as a set of member function pointers. This is purely an implementation detail, as the C++ specification does not mention vtables. Instances of that type will then store a pointer to this table as part of their instance data, complicating scenarios when multiple inheritance is used. Since C++ does not support late binding, the virtual table in a C++ object cannot be modified at runtime, which limits the potential set of dispatch targets to a finite set chosen at compile time.
Type overloading does not produce dynamic dispatch in C++ as the language considers the types of the message parameters part of the formal message name. This means that the message name the programmer sees is not the formal name used for binding.
Go, Rust and Nim implementation
In Go, Rust and Nim, a more versatile variation of early binding is used.
Vtable pointers are carried with object references as 'fat pointers' ('interfaces' in Go, or 'trait objects' in Rust).
This decouples the supported interfaces from the underlying data structures. Each compiled library needn't know the full range of interfaces supported in order to correctly use a type, just the specific vtable layout that they require. Code can pass around different interfaces to the same piece of data to different functions. This versatility comes at the expense of extra data with each object reference, which is problematic if many such references are stored persistently.
The term fat pointer simply refers to a pointer with additional associated information. The additional information may be a vtable pointer for dynamic dispatch described above, but is more commonly the associated object's size to describe e.g. a slice.
Smalltalk implementation
Smalltalk uses a type-based message dispatcher. Each instance has a single type whose definition contains the methods. When an instance receives a message, the dispatcher looks up the corresponding method in the message-to-method map for the type and then invokes the method.
Because a type can have a chain of base types, this look-up can be expensive. A naive implementation of Smalltalk's mechanism would seem to have a significantly higher overhead than that of C++ and this overhead would be incurred for every message that an object receives.
Real Smalltalk implementations often use a technique known as inline caching that makes method dispatch very fast. Inline caching basically stores the previous destination method address and object class of the call site (or multiple pairs for multi-way caching). The cached method is initialized with the most common target method (or just the cache miss handler), based on the method selector. When the method call site is reached during execution, it just calls the address in the cache. (In a dynamic code generator, this call is a direct call as the direct address is back patched by cache miss logic.) Prologue code in the called method then compares the cached class with the actual object class, and if they don't match, execution branches to a cache miss handler to find the correct method in the class. A fast implementation may have multiple cache entries and it often only takes a couple of instructions to get execution to the correct method on an initial cache miss. The common case will be a cached class match, and execution will just continue in the method.
Out-of-line caching can also be used in the method invocation logic, using the object class and method selector. In one design, the class and method selector are hashed, and used as an index into a method dispatch cache table.
As Smalltalk is a reflective language, many implementations allow mutating individual objects into objects with dynamically generated method lookup tables. This allows altering object behavior on a per object basis. A whole category of languages known as prototype-based languages has grown from this, the most famous of which are Self and JavaScript. Careful design of the method dispatch caching allows even prototype-based languages to have high-performance method dispatch.
Many other dynamically typed languages, including Python, Ruby, Objective-C and Groovy use similar approaches.
Example in Python
class Cat:
def speak(self):
print("Meow")
class Dog:
def speak(self):
print("Woof")
def speak(pet):
# Dynamically dispatches the speak method
# pet can either be an instance of Cat or Dog
pet.speak()
cat = Cat()
speak(cat)
dog = Dog()
speak(dog)
Example in C++
#include <iostream>
// make Pet an abstract virtual base class
class Pet {
public:
virtual void speak() = 0;
};
class Dog : public Pet {
public:
void speak() override
{
std::cout << "Woof!\n";
}
};
class Cat : public Pet {
public:
void speak() override
{
std::cout << "Meow!\n";
}
};
// speak() will be able to accept anything deriving from Pet
void speak(Pet& pet)
{
pet.speak();
}
int main()
{
Dog fido;
Cat simba;
speak(fido);
speak(simba);
return 0;
}
See also
Duck typing
Double dispatch
Function overloading
Method overriding
Name binding
References
Further reading
(NB. Something similar to "fat pointers" specifically for Intel's real-mode segment:offset addressing on x86 processors, containing both a deliberately denormalized pointer to a shared code entry point and some info to still distinguish the different callers in the shared code. While, in an open system, pointer-normalizing 3rd-party instances (in other drivers or applications) cannot be ruled out completely on public interfaces, the scheme can be used safely on internal interfaces to avoid redundant entry code sequences.)
[https://web.archive.org/web/20220711181007/https://www.drdobbs.com/architecture-and-design/cs-biggest-mistake/228701625]
Polymorphism (computer science)
Method (computer programming) | Dynamic dispatch | Mathematics | 2,106 |
34,645,248 | https://en.wikipedia.org/wiki/Rosati%20involution | In mathematics, a Rosati involution, named after Carlo Rosati, is an involution of the rational endomorphism ring of an abelian variety induced by a polarisation.
Let be an abelian variety, let be the dual abelian variety, and for , let be the translation-by- map, . Then each divisor on defines a map via . The map is a polarisation if is ample. The Rosati involution of relative to the polarisation sends a map to the map , where is the dual map induced by the action of on .
Let denote the Néron–Severi group of . The polarisation also induces an inclusion via . The image of is equal to , i.e., the set of endomorphisms fixed by the Rosati involution. The operation then gives the structure of a formally real Jordan algebra.
References
Algebraic geometry
Ring theory | Rosati involution | Mathematics | 195 |
2,617,956 | https://en.wikipedia.org/wiki/Spectrum%20continuation%20analysis | Spectrum continuation analysis (SCA) is a generalization of the concept of Fourier series to non-periodic functions of which only a fragment has been sampled in the time domain.
Recall that a Fourier series is only suitable to the analysis of periodic (or finite-domain) functions f(x) with period 2π. It can be expressed as an infinite series of sinusoids:
where is the amplitude of the individual harmonics.
In SCA however, one decomposes the spectrum into optimized discrete frequencies. As a consequence, and as the period of the sampled function is supposed to be infinite or not yet known, each of the discrete periodic functions that compose the sampled function fragment can not be considered to be a multiple of the fundamental frequency:
As such, SCA does not necessarily deliver periodic functions, as would have been the case in Fourier analysis.
For real-valued functions, the SCA series can be written as:
where An and Bn are the series amplitudes. The amplitudes can only be solved if the series of values is previously optimized for a desired objective function (usually least residuals).
is not necessarily the average value over the sampled interval: one might prefer to include predominant information on the behavior of the offset value in the time domain.
Etymology
SCA deals with the prediction problem of continuing a frequency spectrum beyond a sampled (usually stochastic) time series fragment. Unlike ordinary Fourier analysis that infinitely repeats an observed function period or time domain, SCA filters the exact composing frequencies out of the observed spectrum and let them continue (resp. precede) in the time domain.
In the scientific terminology, therefore preference is given to the term continuation rather than for instance extrapolation.
Algorithm
An algorithm is required to cope with several problems: detrending, decomposition, frequency resolution optimization, superposition, transformation and computational efficiency.
Detrending or trend estimation.
Decomposition.
Since discrete Fourier transform is inherently related to Fourier analysis, this type of spectral analysis is by definition not suitable for spectrum decomposition in SCA. DFT (or FFT) may provide however an initial approximation, which often speeds up the decomposition.
Improving frequency resolution.
After decomposition of a discrete frequency, it should be filtered for optimal resolution (i.e. varying three parameters: frequency value, amplitude and phase).
Transformation.
Spectrum dispersion
Compared to DFT (or FFT), which is characterized by perfect spectral resolution, but poor temporal information, SCA favours temporal information, but yields higher spectrum dispersion. This property shows where the analytic strength of SCA is located. For instance, discrete composing frequency resolution is by definition far better in SCA than in DFT.
Fourier analysis
Mathematical series
Digital signal processing
Transforms
Functional analysis | Spectrum continuation analysis | Mathematics | 559 |
31,598,855 | https://en.wikipedia.org/wiki/Fauna%20of%20Turkey | The fauna of Turkey is abundant and very varied. The wildlife of Turkey includes a great diversity of plants and animals, each suited to its own particular habitat, as it is a large country with many geographic and climatic regions About 1500 species of vertebrates have been recorded in the country and around 19,000 species of invertebrate. The country acts as a crossroads with links to Europe, Asia, and the Near East, and many birds use the country as a staging post during migration.
Overview
Turkey has a large range of habitat types and the diversity of its fauna is very great. There are nearly 1,500 species of vertebrate recorded of which over 100 species, mostly fish, are endemic. The country is on two major routes used by migratory birds which swells the numbers in spring and autumn. The invertebrates are also very diverse, with about 19,000 species being recorded including 4,000 endemics.
Invertebrates
Molluscs
Insects
There are over 250 species of ant in Turkey, 48 of which are endemic.
Butterflies
Moths
Arachnids
Vertebrates
Amphibians
Twenty-three species are endemic to Turkey.
Reptiles
Twenty-three species are endemic to Turkey.
Birds
Mammals
Eight species are endemic to Turkey. Many species have declined in numbers, for example chamois, gazelle and mouflon, with shortage of staff to protect them claimed to be a factor. DNA of 15 endangered large mammals will be stored.
Fish
One hundred sixty-one species of freshwater fish are endemic to Turkey.
Conservation
Conservation action plans for 100 species are due to be completed by the end of 2019.
Endangered species
Mediterranean monk seal (Critically endangered) – less than 500 individuals all around the world
Northern bald ibis (Critically endangered) – main groups live in Morocco and Turkey
Asia Minor spiny mouse (Critically endangered)
Rana holtzi (Toros frog; Critically endangered) – endemic to Turkey
Pseudophoxinus maeandricus (Sandıklı spring minnow; Critically endangered) – known from a single stream
Anatolian leopard (Endangered)
White-headed duck (Endangered)
Red-breasted goose (Endangered)
Loggerhead sea turtle (Endangered)
Great bustard (Vulnerable)
Dalmatian pelican (Vulnerable)
Lesser kestrel (Vulnerable)
Egyptian vulture (Vulnerable)
Wild goat (Vulnerable)
Greater spotted eagle (Vulnerable)
Steppe eagle (Endangered)
Eastern imperial eagle (Vulnerable)
Saker falcon (Vulnerable)
Extinct and locally extinct fauna
The following species and populations have become extinct in Turkey in historical times.
African darter, due to the drying up of Lake Amik
Asiatic lion
Caspian tiger, the last known individual was shot in 1974 in Hakkari Province
Hydruntine, extinct species of wild ass. Youngest known specimens in Turkey date to the 1st millennium BC.
Alburnus akili extinct species of fish formerly native to Lake Beyşehir, last seen in 1998, likely became extinct due to the introduction of invasive fish species
Pseudophoxinus handlirschi extinct fish found in Lake Eğirdir, last seen in the 1980s, likely due to the introduction of invasive zander.
Küre and Kaçkar Mountains National Parks have been suggested for rewilding.
See also
Fauna of Europe
Fauna of Asia
References
External links
National Biodiversity Database (requires logon)
Biota of Turkey | Fauna of Turkey | Biology | 672 |
27,354,368 | https://en.wikipedia.org/wiki/Ellison%E2%80%93Cliffe%20Lecture | The Ellison–Cliffe Lecture is held annually by the Royal Society of Medicine. The lecture series, which commenced in 1987 is named after Percy Cliffe and his wife, Carice Ellison, who endowed the lecture to be given on a subject connected with the contribution of fundamental science to the advancement of medicine.
The Lecturer is also awarded a medal in honour for their presentation.
The Lectures
1987 Sir Walter Bodmer, on Genetics and Cancer
1988 Charles D. Marsden
1989 Dame Anne McLaren, on human conceptus
1990 Sir Roy Calne
1991 Lord George Porter
1992 Sir Joseph Smith, on the Threat of new Infectious Diseases
1993 Sir Colin Blakemore
1994 Sir James Black
1995 Dennis Lincoln
1996 Roger H. Clarke, on Managing Radiation Risks
1997 John Newsom-Davis
1998 Marcus Pembrey
1999 William P. Gray
2000 Richard Frackowiak
2001 A. Riley
2002 A. Smith
2003 Stephen T. Holgate CBE
2004 Dame Julia Polak, on embryonic stem cells and tissue engineering
2005 Iain Hutchison
2006 Jill Belch, Blood vessels: Not merely plumbing
2007 Tony Ryan, on nanotechnology and the quest for motility
2008 Chris Lavy
2009 Andy Adam
2010 Hugh Montgomery
2011 Kevin Warwick, Neural Interfaces: An experimental tour
2012 Kevin Fong, on Medicine for Mars
2013 Philip Beales
2014 Michael Hastings, on circadian body clocks
2015 Paul Freemont, life is what you make it
2016 Carl Philpott, Smell and taste - the senses that man forgot
2017 Charles Swanton, Cancer evolution through space and time - The challenge of prolonging survival
2018 Mustafa Suleyman, How AI is going to impact healthcare in the future
2019 Guy Leschziner, Sleep medicine
2021 Mark Lythgoe, The limits of perception: advances in biomedical imaging
2024 Christopher Bishop, Artificial intelligence in science and medicine
See also
List of medicine awards
References
Annual events in London
Awards established in 1987
British lecture series
British science and technology awards
Medical lecture series
Medicine awards
Royal Society of Medicine
Recurring events established in 1987
1987 establishments in the United Kingdom | Ellison–Cliffe Lecture | Technology | 409 |
4,256,110 | https://en.wikipedia.org/wiki/Metre%20per%20hour | Metre per hour (American spelling: meter per hour) is a metric unit of both speed (scalar) and velocity (Vector (geometry)). Its symbol is m/h or m·h−1 (not to be confused with the imperial unit symbol mph). By definition, an object travelling at a speed of 1 m/h for an hour would move 1 metre.
The term is rarely used however as the units of metres per second and kilometres per hour are considered sufficient for the majority of circumstances. Metres per hour can however be convenient for documenting extremely slow moving objects. A Garden Snail for instance, typically moves at a speed of up to 47 metres per hour.
Conversions
3,600 m/h ≡ 1 m·s−1, the SI derived unit of speed, metre per second
1 m/h ≈ 0.00027778 m/s
1 m/h ≈ 0.00062137 mph ≈ 0.00091134 feet per second
How to convert
To convert from kilometers per hour to meters per hour, multiply the figure by 1,000 (hence the prefix kilo- from the ancient Greek language word for thousand).
To convert from meters per second to meters per hour, divide the figure by 3,600 (that is 60 * 60, i.e. 60 seconds for each of the 60 minutes).
See also
Orders of magnitude (speed)
References
Units of velocity | Metre per hour | Mathematics | 289 |
24,220,458 | https://en.wikipedia.org/wiki/Super%20Tonks%E2%80%93Girardeau%20gas | In physics, the super Tonks–Girardeau gas represents an excited quantum gas phase with strong attractive interactions in a one-dimensional spatial geometry.
Usually, strongly attractive quantum gases are expected to form dense particle clusters and lose all gas-like properties. But in 2005, it was proposed by Stefano Giorgini and co-workers that there is a many-body state of attractively interacting bosons that does not decay in one-dimensional systems. If prepared in a special way, this lowest gas-like state should be stable and show new quantum mechanical properties.
Particles in a super-Tonks gas should be strongly correlated and show long range order with a Luttinger liquid parameter K<1. Since each particle occupies a certain volume, the gas properties are similar to a classical gas of hard rods. Despite the mutual attraction, the single particle wave functions separate and the bosons behave similar to fermions with repulsive, long-range interaction.
To prepare the super-Tonks–Girardeau phase it is necessary to increase the repulsive interaction strength all the way through the Tonks–Girardeau regime up to infinity. Sudden switching from infinitely strong repulsive to infinitely attractive interactions stabilizes the gas against collapse and connects the ground state of the Tonks gas to the excited state of the super-Tonks gas.
Experimental realization
The super-Tonks–Girardeau gas was experimentally observed in Ref. using an ultracold gas of cesium atoms. Reducing the magnitude of the attractive interactions caused the gas to became unstable to collapse into cluster-like bound states. Repulsive dipolar interactions stabilize the gas when instead using highly magnetic dysprosium atoms. This enabled the creation of prethermal quantum many-body scar states via the topological pumping of these super-Tonks-Girardeau gases.
References
Condensed matter physics | Super Tonks–Girardeau gas | Physics,Chemistry,Materials_science,Engineering | 378 |
26,663,863 | https://en.wikipedia.org/wiki/Jacob%20Lurie | Jacob Alexander Lurie (born December 7, 1977) is an American mathematician who is a professor at the Institute for Advanced Study. In 2014, Lurie received a MacArthur Fellowship. Lurie's research interests are algebraic geometry, topology, and homotopy theory.
Life
When he was a student in the Science, Mathematics, and Computer Science Magnet Program at Montgomery Blair High School, Lurie took part in the International Mathematical Olympiad, where he won a gold medal with a perfect score in 1994. In 1996 he took first place in the Westinghouse Science Talent Search and was featured in a front-page story in the Washington Times.
Lurie earned his bachelor's degree in mathematics from Harvard College in 2000 and was awarded in the same year the Morgan Prize for his undergraduate thesis on Lie algebras. He earned his Ph.D. from the Massachusetts Institute of Technology under supervision of Michael J. Hopkins, in 2004 with a thesis on derived algebraic geometry. In 2007, he became associate professor at MIT, and in 2009 he became professor at Harvard University. In 2019, he joined the Institute for Advanced Study as a permanent faculty member in mathematics.
Mathematical work
Lurie's research interests started with logic and the theory of surreal numbers when he was in high school. He is best known for his work, starting with his thesis, on infinity categories and derived algebraic geometry. Derived algebraic geometry is a way of infusing homotopical methods into algebraic geometry, with two purposes: deeper insight into algebraic geometry (e.g. into intersection theory) and the use of methods of algebraic geometry in stable homotopy theory. The latter area is the topic of Lurie's work on elliptic cohomology. Infinity categories (in the form of André Joyal's quasi-categories) are a convenient framework to do homotopy theory in abstract settings. They are the main topic of his book Higher Topos Theory.
Another part of Lurie's work is his article on topological field theories, where he sketches a classification of extended field theories using the language of infinity categories (cobordism hypothesis). In joint work with Dennis Gaitsgory, he used his non-abelian Poincaré duality in an algebraic-geometric setting, to prove the Siegel mass formula for function fields.
Lurie was one of the inaugural winners of the Breakthrough Prize in Mathematics in 2014, "for his work on the foundations of higher category theory and derived algebraic geometry; for the classification of fully extended topological quantum field theories; and for providing a moduli-theoretic interpretation of elliptic cohomology." Lurie was also awarded a MacArthur "genius grant" Fellowship in 2014.
Publications
Lurie, Jacob (2017), Higher Algebra
Lurie, Jacob (2018), Spectral Algebraic Geometry
References
External links
Lurie's website at the Institute for Advanced Study
Lurie's website at Harvard (Jacob Lurie's Home Page)
1977 births
Living people
People from Washington, D.C.
21st-century American mathematicians
Harvard College alumni
MacArthur Fellows
Massachusetts Institute of Technology alumni
Harvard University Department of Mathematics faculty
International Mathematical Olympiad participants
Category theorists
Higher category theory
Institute for Advanced Study faculty | Jacob Lurie | Mathematics | 644 |
23,048,210 | https://en.wikipedia.org/wiki/Nicking%20enzyme | A nicking enzyme (or nicking endonuclease) is an enzyme that cuts only one strand of a double-stranded DNA or RNA molecule at a specific recognition nucleotide sequence known as the restriction site. Such enzymes hydrolyze (cut) only one strand of the DNA duplex, to produce DNA molecules that are “nicked”, rather than cleaved.
They can be used for strand-displacement amplification, Nicking Enzyme Amplification Reaction, exonucleolytic degradation, the creation of small gaps, or nick translation. The latter process has been successfully used to incorporate both radioactively labelled nucleotides and fluorescent nucleotides allowing specific regions on a double stranded DNA to be studied. Over 200 nicking enzymes have been studied, and 13 of these are available commercially and are routinely used for research and in commercial products.
References
External links
New England Biolabs Nicking Enzymes
Fermentas Nicking Enzymes
Molecular biology
Biotechnology
Enzymes | Nicking enzyme | Chemistry,Biology | 203 |
2,761,656 | https://en.wikipedia.org/wiki/Walrasian%20auction | A Walrasian auction, introduced by Léon Walras, is a type of simultaneous auction where each agent calculates its demand for the good at every possible price and submits this to an auctioneer. The price is then set so that the total demand across all agents equals the total amount of the good. Thus, a Walrasian auction perfectly matches the supply and the demand.
Walras suggested that equilibrium would always be achieved through a process of tâtonnement (French for "trial and error"), a form of hill climbing. In the 1970s, however, the Sonnenschein–Mantel–Debreu theorem proved that such a process would not necessarily reach a unique and stable equilibrium, even if the market is populated with perfectly rational agents.
Walrasian auctioneer
The Walrasian auctioneer is the presumed auctioneer that matches supply and demand in a market of perfect competition. The auctioneer provides for the features of perfect competition: perfect information and no transaction costs. The process is called tâtonnement, or groping, relating to finding the market clearing price for all commodities and giving rise to general equilibrium.
The device is an attempt to avoid one of deepest conceptual problems of perfect competition, which may, essentially, be defined by the stipulation that no agent can affect prices. But if no one can affect prices no one can change them, so prices cannot change. However, involving as it does an artificial solution, the device is less than entirely satisfactory.
As a mistranslation
Until Walker and van Daal's 2014 translation (retitled Elements of Theoretical Economics), William Jaffé's Elements of Pure Economics (1954) was for many years the only English translation of Walras's Éléments d’économie politique pure.
Walker and van Daal argue that the idea of the Walrasian auction and Walrasian auctioneer resulted from Jaffé's mistranslation of the French word crieurs (criers) into auctioneers. Walker and van Daal call this "a momentous error that has misled generations of readers into thinking that the markets in Walras's model are auction markets and that he assigned the function of changing prices in his model to an auctioneer."
See also
Double auction
Walras' law
Fisher market - a different market model.
Arrow-Debreu market - yet another market model.
References
Bibliography
Eponyms in economics
Types of auction
Wholesale markets
General equilibrium theory
Mathematical optimization | Walrasian auction | Mathematics | 507 |
47,951,565 | https://en.wikipedia.org/wiki/KN-02%20Toksa | The KN-02 Toksa (), Hwasong-11 is a North Korean reverse-engineered locally produced modification of the OTR-21 Tochka short-range ballistic missile.
Design and development
In 1983, Syria acquired a number of 9K79 Tochka (SS-21 Scarab-A) missiles from the Soviet Union, a single-stage, solid-propellant guided missile with a range of 70 km and a CEP of 160 m. In 1996, Syrian missile technicians provided North Korea with technical data on the missiles, then shipped some of the missiles themselves. The first test of a North Korean-produced version occurred in April 2004 and was a failure, but it was then successfully fired on 1 May 2005 into the Sea of Japan; the KN-02 has been tested at least 17 times. Initial production is believed to have begun in 2006, with the missile displayed aboard a launcher during a military parade in April 2007, and entering service in 2008. At least 50 missiles are speculated to be in service.
The KN-02 is a short-range, road-mobile ballistic missile, broadly equivalent to the improved Scarab-B. Although it has a shorter range than other North Korean missiles like the Scud-C, it has superior accuracy of near 100 meters CEP through inertial guidance with an optical correlation system in the terminal phase, making it the most accurate ballistic missile in the inventory; this enables it to be used for precision strikes against priority targets such as airfields, command posts, bridges, storage facilities, and even enemy troops concentrations in a tactical support role on the battlefield. Its warhead weighs and likely consists of a high-explosive, submunition, thermonuclear, chemical payload; Russian engineers could equip the OTR-21 with a 100 kiloton nuclear warhead. The missile has a range of , and it may be capable of traveling through reducing payload to .
A significant difference between the Russian OTR-21 and North Korean KN-02 is the transporter erector launcher (TEL). While the Russian missile is transported and fired from the 6×6 9P129 that has amphibious capabilities, the KN-02's TEL is a locally fabricated version of the Belarusian MAZ-630308-224 or -243 6×4 or 6×6 commercial heavy utility truck, which has a maximum road speed of and is not amphibious. The vehicle has a short firing cycle, able to be ready for launch in 16 minutes, launch the missile in 2 minutes, and be reloaded in 20 minutes by a supporting reloader vehicle of the same design fitted with a crane and holding 2-4 more missiles.
Further developments
In 2013, South Korean intelligence reports suggested that North Korea was developing an anti-ship ballistic missile version of the KN-02. Its range is estimated to be , longer than current KN-01 variants, and it would be much more difficult to intercept due to its faster speed.
In March 2014, a South Korean military source claimed that the KN-02's range had been extended to through improved engine performance. The source also claimed that North Korea possessed 100 missiles with 30 TELs deployed to fire them. In August 2014, three KN-02s were fired out to a range of and estimated to have 100 meter circular error probable accuracy.
Extended range Hwasong-11/KN-02 is referred to as KN-10. It is expected that range of the missile is greater than 230 kilometers.
The U.S. identified the KN-10 system back in 2010.
Operators
Russia
See also
OTR-21 Tochka
References
Short-range ballistic missiles
Tactical ballistic missiles of North Korea
Theatre ballistic missiles
Chemical weapon delivery systems
Military equipment introduced in the 2000s | KN-02 Toksa | Chemistry | 767 |
2,446,166 | https://en.wikipedia.org/wiki/Stewart%20Myers | Stewart Clay Myers is the Robert C. Merton Professor of Financial Economics at the MIT Sloan School of Management.
He is notable for his work on capital structure and innovations in capital budgeting and valuation, and has had a "remarkable influence" on both the theory and practice of corporate finance. Myers, in fact, coined the term "real option". He is the co-author with Richard A. Brealey and Franklin Allen of Principles of Corporate Finance, a widely used and cited business school textbook, now in its 11th edition. He is also the author of dozens of research articles.
Career
He holds an A.B. from Williams College and a Ph.D. and MBA from Stanford University. He began teaching at MIT Sloan School of Management in 1966.
His contributions are seen as falling into three main categories:
Work on capital structure, focusing on "debt overhang" and "pecking order theory".
Contributions to capital budgeting that complement his research on capital structure. He is notable for the adjusted present value (or APV) approach as well as for recognizing the "option-like" character of many corporate assets.
Work on estimating fair rates of return for public utilities.
Recent projects include the valuation of investments in R&D, risk management, and the allocation of capital in diversified firms, and the theory of corporate governance.
As of 2010, he was a principal of economic consulting firm The Brattle Group. He is a past president of the American Finance Association, a research associate of the National Bureau of Economic Research, and a director of the Cambridge Endowment for Research in Finance.
Works
Stewart C. Myers (ed) Modern Developments in Financial Management, Dryden Press, 1976,
Alexander A. Robichek, Stewart C. Myers, Optimal financing decisions, Prentice-Hall, 1965
Richard A. Brealey, Stewart C. Myers, Capital Investment and Valuation, McGraw Hill Professional, 2003,
References
External links
Stewart Myers - MIT Sloan Biography
Business Week Profile
Publication list
The Contributions of Stewart Myers to the Theory and Practice of Corporate Finance, Journal of Applied Corporate Finance
Living people
Financial economists
American finance and investment writers
American textbook writers
American male non-fiction writers
Williams College alumni
Corporate finance theorists
Real options
MIT Sloan School of Management faculty
Presidents of the American Finance Association
Year of birth missing (living people) | Stewart Myers | Engineering | 467 |
38,635,705 | https://en.wikipedia.org/wiki/Dijet%20event | In particle physics, a dijet event is a collision between subatomic particles that produces two particle jets.
Dijet events are measured at the LHC to constrain QCD models, in particular the parton evolution equations and parton distribution functions. This is accomplished by measuring the azimuthal correlations between the two jets.
References
Experimental particle physics | Dijet event | Physics | 75 |
14,366,304 | https://en.wikipedia.org/wiki/HD%2072659 | HD 72659 is a star in the equatorial constellation of Hydra. With an apparent visual magnitude of 7.46, his yellow-hued star is too faint to be viewed with the naked eye. Parallax measurements provide a distance estimate of 169.4 light years from the Sun, and it has an absolute magnitude of 3.98. The star is drifting closer with a radial velocity of −18.3 km/s.
This is a Sun-like main sequence star with a stellar classification of G2V, indicating that it is generating energy through core hydrogen fusion. It is older than the Sun with an age of about seven billion years, and is spinning with a projected rotational velocity of 5.1 km/s. The star has 7% greater mass than the Sun and a 38% larger radius. It is radiating more than double the Sun's luminosity from its photosphere at an effective temperature of 5,956 K. The metallicity of the stellar atmosphere is similar to the Sun.
Planetary system
An extrasolar planet was discovered orbiting this star in 2003 via the Doppler method. This is a superjovian planet with an eccentric orbit, completing a lap around its host star every . In 2022, the inclination and true mass of HD 72659 b were measured via astrometry, along with the detection of a second substellar companion, likely a brown dwarf.
See also
HD 73256
List of extrasolar planets
References
External links
G-type main-sequence stars
Planetary systems with one confirmed planet
Hydra (constellation)
Durchmusterung objects
072659
042030
J08340320-0134056 | HD 72659 | Astronomy | 342 |
2,917,649 | https://en.wikipedia.org/wiki/Speech | Speech is the use of the human voice as a medium for language. Spoken language combines vowel and consonant sounds to form units of meaning like words, which belong to a language's lexicon. There are many different intentional speech acts, such as informing, declaring, asking, persuading, directing; acts may vary in various aspects like enunciation, intonation, loudness, and tempo to convey meaning. Individuals may also unintentionally communicate aspects of their social position through speech, such as sex, age, place of origin, physiological and mental condition, education, and experiences.
While normally used to facilitate communication with others, people may also use speech without the intent to communicate. Speech may nevertheless express emotions or desires; people talk to themselves sometimes in acts that are a development of what some psychologists (e.g., Lev Vygotsky) have maintained is the use of silent speech in an interior monologue to vivify and organize cognition, sometimes in the momentary adoption of a dual persona as self addressing self as though addressing another person. Solo speech can be used to memorize or to test one's memorization of things, and in prayer or in meditation.
Researchers study many different aspects of speech: speech production and speech perception of the sounds used in a language, speech repetition, speech errors, the ability to map heard spoken words onto the vocalizations needed to recreate them, which plays a key role in children's enlargement of their vocabulary, and what different areas of the human brain, such as Broca's area and Wernicke's area, underlie speech. Speech is the subject of study for linguistics, cognitive science, communication studies, psychology, computer science, speech pathology, otolaryngology, and acoustics. Speech compares with written language, which may differ in its vocabulary, syntax, and phonetics from the spoken language, a situation called diglossia.
The evolutionary origin of speech is subject to debate and speculation. While animals also communicate using vocalizations, and trained apes such as Washoe and Kanzi can use simple sign language, no animals' vocalizations are articulated phonemically and syntactically, and do not constitute speech.
Evolution
Although related to the more general problem of the origin of language, the evolution of distinctively human speech capacities has become a distinct and in many ways separate area of scientific research. The topic is a separate one because language is not necessarily spoken: it can equally be written or signed. Speech is in this sense optional, although it is the default modality for language.
Monkeys, non-human apes and humans, like many other animals, have evolved specialised mechanisms for producing sound for purposes of social communication. On the other hand, no monkey or ape uses its tongue for such purposes. The human species' unprecedented use of the tongue, lips and other moveable parts seems to place speech in a quite separate category, making its evolutionary emergence an intriguing theoretical challenge in the eyes of many scholars.
Determining the timeline of human speech evolution is made additionally challenging by the lack of data in the fossil record. The human vocal tract does not fossilize, and indirect evidence of vocal tract changes in hominid fossils has proven inconclusive.
Production
Speech production is an unconscious multi-step process by which thoughts are generated into spoken utterances. Production involves the unconscious mind selecting appropriate words and the appropriate form of those words from the lexicon and morphology, and the organization of those words through the syntax. Then, the phonetic properties of the words are retrieved and the sentence is articulated through the articulations associated with those phonetic properties.
In linguistics, articulatory phonetics is the study of how the tongue, lips, jaw, vocal cords, and other speech organs are used to make sounds. Speech sounds are categorized by manner of articulation and place of articulation. Place of articulation refers to where in the neck or mouth the airstream is constricted. Manner of articulation refers to the manner in which the speech organs interact, such as how closely the air is restricted, what form of airstream is used (e.g. pulmonic, implosive, ejectives, and clicks), whether or not the vocal cords are vibrating, and whether the nasal cavity is opened to the airstream. The concept is primarily used for the production of consonants, but can be used for vowels in qualities such as voicing and nasalization. For any place of articulation, there may be several manners of articulation, and therefore several homorganic consonants.
Normal human speech is pulmonic, produced with pressure from the lungs, which creates phonation in the glottis in the larynx, which is then modified by the vocal tract and mouth into different vowels and consonants. However humans can pronounce words without the use of the lungs and glottis in alaryngeal speech, of which there are three types: esophageal speech, pharyngeal speech and buccal speech (better known as Donald Duck talk).
Errors
Speech production is a complex activity, and as a consequence errors are common, especially in children. Speech errors come in many forms and are used to provide evidence to support hypotheses about the nature of speech. As a result, speech errors are often used in the construction of models for language production and child language acquisition. For example, the fact that children often make the error of over-regularizing the -ed past tense suffix in English (e.g. saying 'singed' instead of 'sang') shows that the regular forms are acquired earlier. Speech errors associated with certain kinds of aphasia have been used to map certain components of speech onto the brain and see the relation between different aspects of production; for example, the difficulty of expressive aphasia patients in producing regular past-tense verbs, but not irregulars like 'sing-sang' has been used to demonstrate that regular inflected forms of a word are not individually stored in the lexicon, but produced from affixation to the base form.
Perception
Speech perception refers to the processes by which humans can interpret and understand the sounds used in language. The study of speech perception is closely linked to the fields of phonetics and phonology in linguistics and cognitive psychology and perception in psychology. Research in speech perception seeks to understand how listeners recognize speech sounds and use this information to understand spoken language. Research into speech perception also has applications in building computer systems that can recognize speech, as well as improving speech recognition for hearing- and language-impaired listeners.
Speech perception is categorical, in that people put the sounds they hear into categories rather than perceiving them as a spectrum. People are more likely to be able to hear differences in sounds across categorical boundaries than within them. A good example of this is voice onset time (VOT), one aspect of the phonetic production of consonant sounds. For example, Hebrew speakers, who distinguish voiced /b/ from voiceless /p/, will more easily detect a change in VOT from -10 ( perceived as /b/ ) to 0 ( perceived as /p/ ) than a change in VOT from +10 to +20, or -10 to -20, despite this being an equally large change on the VOT spectrum.
Development
Most human children develop proto-speech babbling behaviors when they are four to six months old. Most will begin saying their first words at some point during the first year of life. Typical children progress through two or three word phrases before three years of age followed by short sentences by four years of age.
Repetition
In speech repetition, speech being heard is quickly turned from sensory input into motor instructions needed for its immediate or delayed vocal imitation (in phonological memory). This type of mapping plays a key role in enabling children to expand their spoken vocabulary. Masur (1995) found that how often children repeat novel words versus those they already have in their lexicon is related to the size of their lexicon later on, with young children who repeat more novel words having a larger lexicon later in development. Speech repetition could help facilitate the acquisition of this larger lexicon.
Problems
There are several organic and psychological factors that can affect speech. Among these are:
Diseases and disorders of the lungs or the vocal cords, including paralysis, respiratory infections (bronchitis), vocal fold nodules and cancers of the lungs and throat.
Diseases and disorders of the brain, including alogia, aphasias, dysarthria, dystonia and speech processing disorders, where impaired motor planning, nerve transmission, phonological processing or perception of the message (as opposed to the actual sound) leads to poor speech production.
Hearing problems, such as otitis media with effusion, and listening problems, auditory processing disorders, can lead to phonological problems. In addition to dysphasia, anomia and auditory processing disorder impede the quality of auditory perception, and therefore, expression. Those who are deaf or hard of hearing may be considered to fall into this category.
Articulatory problems, such as slurred speech, stuttering, lisping, cleft palate, ataxia, or nerve damage leading to problems in articulation. Tourette syndrome and tics can also affect speech. Various congenital and acquired tongue diseases can affect speech as can motor neuron disease.
Psychiatric disorders have been shown to change speech acoustic features, where for instance, fundamental frequency of voice (perceived as pitch) tends to be significantly lower in major depressive disorder than in healthy controls. Therefore, speech is being investigated as a potential biomarker for mental health disorders.
Speech and language disorders can also result from stroke, brain injury, hearing loss, developmental delay, a cleft palate, cerebral palsy, or emotional issues.
Treatment
Speech-related diseases, disorders, and conditions can be treated by a speech-language pathologist (SLP) or speech therapist. SLPs assess levels of speech needs, make diagnoses based on the assessments, and then treat the diagnoses or address the needs.
Brain physiology
Classical model
The classical or Wernicke-Geschwind model of the language system in the brain focuses on Broca's area in the inferior prefrontal cortex, and Wernicke's area in the posterior superior temporal gyrus on the dominant hemisphere of the brain (typically the left hemisphere for language). In this model, a linguistic auditory signal is first sent from the auditory cortex to Wernicke's area. The lexicon is accessed in Wernicke's area, and these words are sent via the arcuate fasciculus to Broca's area, where morphology, syntax, and instructions for articulation are generated. This is then sent from Broca's area to the motor cortex for articulation.
Paul Broca identified an approximate region of the brain in 1861 which, when damaged in two of his patients, caused severe deficits in speech production, where his patients were unable to speak beyond a few monosyllabic words. This deficit, known as Broca's or expressive aphasia, is characterized by difficulty in speech production where speech is slow and labored, function words are absent, and syntax is severely impaired, as in telegraphic speech. In expressive aphasia, speech comprehension is generally less affected except in the comprehension of grammatically complex sentences. Wernicke's area is named after Carl Wernicke, who in 1874 proposed a connection between damage to the posterior area of the left superior temporal gyrus and aphasia, as he noted that not all aphasic patients had had damage to the prefrontal cortex. Damage to Wernicke's area produces Wernicke's or receptive aphasia, which is characterized by relatively normal syntax and prosody but severe impairment in lexical access, resulting in poor comprehension and nonsensical or jargon speech.
Modern research
Modern models of the neurological systems behind linguistic comprehension and production recognize the importance of Broca's and Wernicke's areas, but are not limited to them nor solely to the left hemisphere. Instead, multiple streams are involved in speech production and comprehension. Damage to the left lateral sulcus has been connected with difficulty in processing and producing morphology and syntax, while lexical access and comprehension of irregular forms (e.g. eat-ate) remain unaffected.
Moreover, the circuits involved in human speech comprehension dynamically adapt with learning, for example, by becoming more efficient in terms of processing time when listening to familiar messages such as learned verses.
Animal communication
Some non-human animals can produce sounds or gestures resembling those of a human language. Several species or groups of animals have developed forms of communication which superficially resemble verbal language, however, these usually are not considered a language because they lack one or more of the defining characteristics, e.g. grammar, syntax, recursion, and displacement. Researchers have been successful in teaching some animals to make gestures similar to sign language, although whether this should be considered a language has been disputed.
See also
FOXP2
Freedom of speech
Imagined speech
Index of linguistics articles
List of language disorders
Origin of speech
Spatial hearing loss
Speechwriter
Talking birds
Vocology
References
Further reading
Fitzpatrick, Élizabeth M. Apprendre à écouter et à parler. University of Ottawa Press, 2013. Available at Project MUSE.
External links
Speaking captured by real-time MRI, YouTube
Language
Animal sounds
Articles containing video clips | Speech | Biology | 2,779 |
68,897,186 | https://en.wikipedia.org/wiki/Yang-Hui%20He | Yang-Hui He (; born 29 September 1975) is a mathematical physicist, who is a Fellow at the London Institute, which is based at the Royal Institution of Great Britain, as well as lecturer and former Fellow at Merton College, Oxford. He holds honorary positions as visiting professor of mathematics at City, University of London, Chang-Jiang Chair professor at Nankai University, and President of STEMM Global scientific society.
Yang works on the interface between quantum field theory, string theory, algebraic geometry and number theory, as well as how AI and machine-learning help with these problems. He is one of the pioneers of the field of using AI for pure mathematics.
Yang is author of over 200 scientific publications and is also a keen communicator of science, giving regular public lectures including the Royal Institution Friday Evening Discourse ,
as well as podcasts.
His other outreach activities include acting as an advisor to BMUCO and being a fellow of the One Garden.
Education and career
Yang received his A.B. in Physics from Princeton University in 1996, with Highest Honours (summa cum laude, Allen Shenstone Prize and Kusaka Memorial Prize), joint with certificates in applied mathematics and in engineering physics. He received his Masters from University of Cambridge in 1997 with Distinction and then obtained his PhD from MIT in 2002 in the Center for Theoretical Physics (NSF Scholarship and MIT Presidential Award) under the supervision of Amihay Hanany.
After postdoctoral work at the University of Pennsylvania, in the group of Burt Ovrut, Yang joined the University of Oxford as FitzJames Fellow and Advanced Fellow of the STFC, UK, working closely with Philip Candelas. He remains a tutor at Merton College, Oxford when taking up his professorships at the University of London and Nankai University, and more recently, when he joined the London Institute.
Works
Yang has authored over 200 journal papers, as well as several books, notably:
Topology and Physics, co-edited with C. N. Yang and Mo-Lin Ge, with contributions from Sir Michael Atiyah, Edward Witten, Sir Roger Penrose, Robbert Dijkgraaf et al., recommended by Book Authority as one of the 20 most influential books in quantum field theory of all time.
The Calabi-Yau Landscape: from geometry, to physics, to machine-learning, textbook aimed at early PhD students, introducing mathematics to physicists, physics to mathematicians and machine-learning to both, the first textbook on the AI mathematician.
Dialogues Between Physics and Mathematics: C. N. Yang at 100, co-edited with Mo-Lin Ge, with contributions from Edward Witten, Sir Roger Penrose, Sir Anthony James Leggett, Alexander Polyakov, Vladimir Drinfeld et al., celebrating the 100th birthday of C. N. Yang.
Machine Learning in Pure Mathematics and Theoretical Physics, the first of its kind, as a collection of essays on the interactions between AI and pure mathematics/fundamental physics.
References
External links
1975 births
Academics of the University of London
Academic staff of Nankai University
Mathematical physicists
Quantum physicists
Living people
Massachusetts Institute of Technology alumni | Yang-Hui He | Physics | 634 |
52,565 | https://en.wikipedia.org/wiki/Partial%20derivative | In mathematics, a partial derivative of a function of several variables is its derivative with respect to one of those variables, with the others held constant (as opposed to the total derivative, in which all variables are allowed to vary). Partial derivatives are used in vector calculus and differential geometry.
The partial derivative of a function with respect to the variable is variously denoted by
It can be thought of as the rate of change of the function in the -direction.
Sometimes, for the partial derivative of with respect to is denoted as Since a partial derivative generally has the same arguments as the original function, its functional dependence is sometimes explicitly signified by the notation, such as in:
The symbol used to denote partial derivatives is ∂. One of the first known uses of this symbol in mathematics is by Marquis de Condorcet from 1770, who used it for partial differences. The modern partial derivative notation was created by Adrien-Marie Legendre (1786), although he later abandoned it; Carl Gustav Jacob Jacobi reintroduced the symbol in 1841.
Definition
Like ordinary derivatives, the partial derivative is defined as a limit. Let be an open subset of and a function. The partial derivative of at the point with respect to the -th variable is defined as
Where is the unit vector of -th variable . Even if all partial derivatives exist at a given point , the function need not be continuous there. However, if all partial derivatives exist in a neighborhood of and are continuous there, then is totally differentiable in that neighborhood and the total derivative is continuous. In this case, it is said that is a function. This can be used to generalize for vector valued functions, by carefully using a componentwise argument.
The partial derivative can be seen as another function defined on and can again be partially differentiated. If the direction of derivative is repeated, it is called a mixed partial derivative. If all mixed second order partial derivatives are continuous at a point (or on a set), is termed a function at that point (or on that set); in this case, the partial derivatives can be exchanged by Clairaut's theorem:
Notation
For the following examples, let be a function in , , and .
First-order partial derivatives:
Second-order partial derivatives:
Second-order mixed derivatives:
Higher-order partial and mixed derivatives:
When dealing with functions of multiple variables, some of these variables may be related to each other, thus it may be necessary to specify explicitly which variables are being held constant to avoid ambiguity. In fields such as statistical mechanics, the partial derivative of with respect to , holding and constant, is often expressed as
Conventionally, for clarity and simplicity of notation, the partial derivative function and the value of the function at a specific point are conflated by including the function arguments when the partial derivative symbol (Leibniz notation) is used. Thus, an expression like
is used for the function, while
might be used for the value of the function at the point However, this convention breaks down when we want to evaluate the partial derivative at a point like In such a case, evaluation of the function must be expressed in an unwieldy manner as
or
in order to use the Leibniz notation. Thus, in these cases, it may be preferable to use the Euler differential operator notation with as the partial derivative symbol with respect to the -th variable. For instance, one would write for the example described above, while the expression represents the partial derivative function with respect to the first variable.
For higher order partial derivatives, the partial derivative (function) of with respect to the -th variable is denoted That is, so that the variables are listed in the order in which the derivatives are taken, and thus, in reverse order of how the composition of operators is usually notated. Of course, Clairaut's theorem implies that as long as comparatively mild regularity conditions on are satisfied.
Gradient
An important example of a function of several variables is the case of a scalar-valued function on a domain in Euclidean space (e.g., on or In this case has a partial derivative with respect to each variable . At the point , these partial derivatives define the vector
This vector is called the gradient of at . If is differentiable at every point in some domain, then the gradient is a vector-valued function which takes the point to the vector . Consequently, the gradient produces a vector field.
A common abuse of notation is to define the del operator () as follows in three-dimensional Euclidean space with unit vectors
Or, more generally, for -dimensional Euclidean space with coordinates and unit vectors
Directional derivative
Example
Suppose that is a function of more than one variable. For instance,
The graph of this function defines a surface in Euclidean space. To every point on this surface, there are an infinite number of tangent lines. Partial differentiation is the act of choosing one of these lines and finding its slope. Usually, the lines of most interest are those that are parallel to the -plane, and those that are parallel to the -plane (which result from holding either or constant, respectively).
To find the slope of the line tangent to the function at and parallel to the -plane, we treat as a constant. The graph and this plane are shown on the right. Below, we see how the function looks on the plane . By finding the derivative of the equation while assuming that is a constant, we find that the slope of at the point is:
So at , by substitution, the slope is . Therefore,
at the point . That is, the partial derivative of with respect to at is , as shown in the graph.
The function can be reinterpreted as a family of functions of one variable indexed by the other variables:
In other words, every value of defines a function, denoted , which is a function of one variable . That is,
In this section the subscript notation denotes a function contingent on a fixed value of , and not a partial derivative.
Once a value of is chosen, say , then determines a function which traces a curve on the -plane:
In this expression, is a , not a , so is a function of only one real variable, that being . Consequently, the definition of the derivative for a function of one variable applies:
The above procedure can be performed for any choice of . Assembling the derivatives together into a function gives a function which describes the variation of in the direction:
This is the partial derivative of with respect to . Here '' is a rounded 'd' called the partial derivative symbol; to distinguish it from the letter 'd', '' is sometimes pronounced "partial".
Higher order partial derivatives
Second and higher order partial derivatives are defined analogously to the higher order derivatives of univariate functions. For the function the "own" second partial derivative with respect to is simply the partial derivative of the partial derivative (both with respect to ):
The cross partial derivative with respect to and is obtained by taking the partial derivative of with respect to , and then taking the partial derivative of the result with respect to , to obtain
Schwarz's theorem states that if the second derivatives are continuous, the expression for the cross partial derivative is unaffected by which variable the partial derivative is taken with respect to first and which is taken second. That is,
or equivalently
Own and cross partial derivatives appear in the Hessian matrix which is used in the second order conditions in optimization problems.
The higher order partial derivatives can be obtained by successive differentiation
Antiderivative analogue
There is a concept for partial derivatives that is analogous to antiderivatives for regular derivatives. Given a partial derivative, it allows for the partial recovery of the original function.
Consider the example of
The so-called partial integral can be taken with respect to (treating as constant, in a similar manner to partial differentiation):
Here, the constant of integration is no longer a constant, but instead a function of all the variables of the original function except . The reason for this is that all the other variables are treated as constant when taking the partial derivative, so any function which does not involve will disappear when taking the partial derivative, and we have to account for this when we take the antiderivative. The most general way to represent this is to have the constant represent an unknown function of all the other variables.
Thus the set of functions where is any one-argument function, represents the entire set of functions in variables that could have produced the -partial derivative
If all the partial derivatives of a function are known (for example, with the gradient), then the antiderivatives can be matched via the above process to reconstruct the original function up to a constant. Unlike in the single-variable case, however, not every set of functions can be the set of all (first) partial derivatives of a single function. In other words, not every vector field is conservative.
Applications
Geometry
The volume of a cone depends on the cone's height and its radius according to the formula
The partial derivative of with respect to is
which represents the rate with which a cone's volume changes if its radius is varied and its height is kept constant. The partial derivative with respect to equals which represents the rate with which the volume changes if its height is varied and its radius is kept constant.
By contrast, the total derivative of with respect to and are respectively
The difference between the total and partial derivative is the elimination of indirect dependencies between variables in partial derivatives.
If (for some arbitrary reason) the cone's proportions have to stay the same, and the height and radius are in a fixed ratio ,
This gives the total derivative with respect to ,
which simplifies to
Similarly, the total derivative with respect to is
The total derivative with respect to and of the volume intended as scalar function of these two variables is given by the gradient vector
Optimization
Partial derivatives appear in any calculus-based optimization problem with more than one choice variable. For example, in economics a firm may wish to maximize profit with respect to the choice of the quantities and of two different types of output. The first order conditions for this optimization are . Since both partial derivatives and will generally themselves be functions of both arguments and , these two first order conditions form a system of two equations in two unknowns.
Thermodynamics, quantum mechanics and mathematical physics
Partial derivatives appear in thermodynamic equations like Gibbs-Duhem equation, in quantum mechanics as in Schrödinger wave equation, as well as in other equations from mathematical physics. The variables being held constant in partial derivatives here can be ratios of simple variables like mole fractions in the following example involving the Gibbs energies in a ternary mixture system:
Express mole fractions of a component as functions of other components' mole fraction and binary mole ratios:
Differential quotients can be formed at constant ratios like those above:
Ratios X, Y, Z of mole fractions can be written for ternary and multicomponent systems:
which can be used for solving partial differential equations like:
This equality can be rearranged to have differential quotient of mole fractions on one side.
Image resizing
Partial derivatives are key to target-aware image resizing algorithms. Widely known as seam carving, these algorithms require each pixel in an image to be assigned a numerical 'energy' to describe their dissimilarity against orthogonal adjacent pixels. The algorithm then progressively removes rows or columns with the lowest energy. The formula established to determine a pixel's energy (magnitude of gradient at a pixel) depends heavily on the constructs of partial derivatives.
Economics
Partial derivatives play a prominent role in economics, in which most functions describing economic behaviour posit that the behaviour depends on more than one variable. For example, a societal consumption function may describe the amount spent on consumer goods as depending on both income and wealth; the marginal propensity to consume is then the partial derivative of the consumption function with respect to income.
See also
d'Alembert operator
Chain rule
Curl (mathematics)
Divergence
Exterior derivative
Iterated integral
Jacobian matrix and determinant
Laplace operator
Multivariable calculus
Symmetry of second derivatives
Triple product rule, also known as the cyclic chain rule.
Notes
External links
Partial Derivatives at MathWorld
Multivariable calculus
Differential operators | Partial derivative | Mathematics | 2,478 |
19,651,455 | https://en.wikipedia.org/wiki/Vacuolar%20fusion%20protein%20Mon1 | SAND protein family, first described in Saccharomyces cerevisiae (but also in the animals Fugu rubripes, Caenorhabditis elegans, Drosophila melanogaster and Homo sapiens and in the plant Arabidopsis thaliana using comparative genomics), is membrane protein related with vesicle traffic: vacuole fusion in yeasts and lysosome one motility in mammals and other taxa. In humans has been described an interaction with HSV-1, a virus which produces Herpes simplex.
See also
SNARE (protein)
References
Membrane proteins
Protein families | Vacuolar fusion protein Mon1 | Chemistry,Biology | 132 |
55,613,887 | https://en.wikipedia.org/wiki/Seascape%20ecology | Seascape ecology is a scientific discipline that deals with the causes and ecological consequences of spatial pattern in the marine environment, drawing heavily on conceptual and analytical frameworks developed in terrestrial landscape ecology.
Overview
Seascape ecology, the application of landscape ecology concepts to the marine environment has been slowly emerging since the 1970s, yielding new ecological insights and showing growing potential to support the development of ecologically meaningful science-based management practices. For marine systems, the application of landscape ecology came about through a recognition that many of the concepts developed in the theory of island biogeography and the study of patch dynamics (precursors to modern landscape ecology) could be applicable to a range of marine environments from plankton patches to patch reefs, inter-tidal mussel beds and seagrass meadows.
Progress in the ecological understanding of spatial patterning was not confined to shallow seafloor environments. For the open ocean, advances in ocean observing systems since the 1970s have allowed scientists to map, classify, quantify and track dynamic spatial structure in the form of eddies, surface roughness, currents, runoff plumes, ice, temperature fronts and plankton patches using oceanographic technologies – a theme increasingly referred to as pelagic seascape ecology. Subsurface structures too, such as internal waves, thermoclines, haloclines, boundary layers and stratification resulting in distinct layering of organisms, is increasingly being mapped and modelled in multiple dimensions.
Like landscape ecologists, seascape ecologists are interested in the spatially explicit geometry of patterns and the relationships between pattern, ecological processes and environmental change. A central tenet in landscape ecology is that patch context matters, where local conditions are influenced by attributes of the surroundings. For instance, the physical arrangement of objects in space, and their location relative to other things, influences how they function.
A landscape ecologist will ask different questions focused at different scales than other scientists, such as: What are the ecological consequences of different shaped patches, patch size, quality, edge geometry, spatial arrangement and diversity of patches across the landscape? At what scale(s) is structure most influential? How do landscape patterns influence the way that animals find food, evade predators and interact with competitors? How does human activity alter the structure and function of landscapes?
Several guiding principles that exist at the core of landscape ecology have made major contributions to terrestrial landscape planning and conservation, but in marine systems our understanding is still in its infancy. The first book on seascape ecology was published in December 2018.
Seascapes are defined broadly as spatially heterogeneous and dynamic spaces that can be delineated at a wide range of scales in time and space. With regard to seascapes defined by sampling units, a 1 m2 quadrant can be a valid seascape sample unit (SSU), just as can a 1 km2 analytical window in a geographical information system. The wide diversity of possible focal scales in marine ecology means that the term seascape cannot be used as an indication of scale, or a level of organization.
Seascape patterns
The sea exhibits complex spatial patterning that can be mapped and quantified, such as gradients in plant communities across tidal saltmarshes or the intricate mosaics of patches typical of coral reefs. In the open ocean too, dynamic spatial structure in the form of water currents, eddies, temperature fronts and plankton patches can be measured readily. Physical processes such as storms dramatically influence spatial patterning in the environment and human activity can also directly create patch structure, modify mosaic composition and even completely remove elements of the seascape. Furthermore, climate-change induced shifts in species related to water temperature change and sea level rise are driving a gradual reconfiguration of the geography of species and habitats.
The patterns revealed by remote sensing devices are most often mapped and represented using two types of model: (1) collections of discrete patches forming mosaics e.g. as represented in two-dimensional benthic habitat map, or (2) continuously varying gradients in three-dimensional terrain models e.g. in remotely sensed Bathymetric data. In landscape ecology, patches can be classified into a binary patch-matrix model based on island biogeography theory where a focal habitat patch type (e.g. seagrasses) is surrounded by an inhospitable matrix (e.g. sand), or a patch-mosaic of interconnected patches, where the interactions of the parts influence the ecological function of the whole mosaic. Both patch and gradient models have provided important insights into the spatial ecology of marine species and biodiversity.
Scale matters
Scale, the spatial or temporal dimensions of a phenomenon, is central to seascape ecology and the topic permeates all applications of a seascape ecology approach from conceptual models through to design of sampling, analyses and interpretation of results. Species and life-stage responses to patchiness and gradients in environmental structure are likely to be scale dependent, therefore, scale selection is an important task in any ecological study. Seascape ecology acknowledges that decisions made for scaling ecological studies influence our perspective and ultimately our understanding of ecological patterns and processes. Historically, marine scientists have played a significant role in communicating the importance of scale in ecology
In 1963, a physical oceanographer, Henry Stommel, published a conceptual diagram that was to have a profound effect on all of the environmental sciences. The diagram depicted variation in sea level height at spatial scales from centimeters to that of the planet and at time scales from seconds to tens of millennia. The oceanographer John Steele (1978) adapted the Stommel diagram to depict the spatial and temporal scales of patchiness in phytoplankton, zooplankton and fish.
Measuring habitat structure at multiple scales is typical in seascape ecology, particularly where a single meaningful scale is not known or not meaningful to the ecological process of interest. Multi-scale measurements have been used to discover the scale at which populations are associated with key habitat features. With regard to scaling seascapes, one approach is to select spatial and temporal scales to be ecologically meaningful to the organism’s movements or other processes of interest.
The absence of information, or the lack of continuous observation on the way animals use space through time, can all too often result in insufficient consideration of seascape context potentially resulting in misleading conclusions on the primary drivers of ecological patterns and processes. Pittman and McAlpine (2003) offer a multi-scale framework for scaling ecological studies that integrates hierarchy theory with movement ecology and the concept of ecological neighborhoods. Here the focal scale is guided by the spatial and temporal scales relevant to an ecological process of interest. The focal scale is nested within a spatial hierarchy that incorporates patterns and processes at both finer and broader scales
Relationship to fisheries and hatcheries
Understanding seascape ecology is important in the study of juvenile fish development, particularly when examining estuaries. Prior investigations into nursery function have predominantly focused on individual habitats or specific species, lacking a comprehensive understanding of the intricate relationships within and among diverse habitat patches. This is of concern due to the frequent oncogenic shifts observed in many juvenile species, which causes them to use multiple habitats throughout their developmental phases. Various habitats, including mangrove roots, macroalgae, seagrasses, and others, offer distinct services and resources crucial for the development of juvenile fish. The failure to consider the entirety of habitats occupied during development may impede ecologists and resource managers in effectively evaluating the conservation value and priority of estuarine regions.
References
Ecology
Landscape ecology
Marine biology | Seascape ecology | Biology | 1,513 |
23,938,639 | https://en.wikipedia.org/wiki/Igmesine | Igmesine (JO-1,784) is a sigma receptor agonist (IC50 = 39 nM (rat brain)). It has neuroprotective and antidepressant-like effects in animal studies, as well as nootropic effects in models of age-related cognitive decline. In two phase II clinical trials, igmesine was found to be effective in the treatment of depression and was as active as the comparator fluoxetine. However, in a large phase III clinical trial, igmesine failed to show significant effectiveness for depression. The drug has not been developed further.
References
Amines
Alkene derivatives
Cyclopropyl compounds
Sigma agonists | Igmesine | Chemistry | 150 |
2,180,593 | https://en.wikipedia.org/wiki/Kirby%E2%80%93Siebenmann%20class | In mathematics, more specifically in geometric topology, the Kirby–Siebenmann class is an obstruction for topological manifolds to allow a PL-structure.
The KS-class
For a topological manifold M, the Kirby–Siebenmann class is an element of the fourth cohomology group of M that vanishes if M admits a piecewise linear structure.
It is the only such obstruction, which can be phrased as the weak equivalence of TOP/PL with an Eilenberg–MacLane space.
The Kirby-Siebenmann class can be used to prove the existence of topological manifolds that do not admit a PL-structure. Concrete examples of such manifolds are , where stands for Freedman's E8 manifold.
The class is named after Robion Kirby and Larry Siebenmann, who developed the theory of topological and PL-manifolds.
See also
Hauptvermutung
References
Homology theory
Geometric topology
Structures on manifolds
Surgery theory | Kirby–Siebenmann class | Mathematics | 198 |
29,504,243 | https://en.wikipedia.org/wiki/N-group%20%28finite%20group%20theory%29 | In mathematical finite group theory, an N-group is a group all of whose local subgroups (that is, the normalizers of nontrivial p-subgroups) are solvable groups. The non-solvable ones were classified by Thompson during his work on finding all the minimal finite simple groups.
Simple N-groups
The simple N-groups were classified by in a series of 6 papers totaling about 400 pages.
The simple N-groups consist of the special linear groups PSL2(q), PSL3(3), the Suzuki groups Sz(22n+1), the unitary group U3(3), the alternating group A7, the Mathieu group M11, and the Tits group. (The Tits group was overlooked in Thomson's original announcement in 1968, but Hearn pointed out that it was also a simple N-group.) More generally Thompson showed that any non-solvable N-group is a subgroup of Aut(G) containing G for some simple N-group G.
generalized Thompson's theorem to the case of groups where all 2-local subgroups are solvable. The only extra simple groups that appear are the unitary groups U3(q).
Proof
gives a summary of Thompson's classification of N-groups.
The primes dividing the order of the group are divided into four classes π1, π2, π3, π4 as follows
π1 is the set of primes p such that a Sylow p-subgroup is nontrivial and cyclic.
π2 is the set of primes p such that a Sylow p-subgroup P is non-cyclic but SCN3(P) is empty
π3 is the set of primes p such that a Sylow p-subgroup P has SCN3(P) nonempty and normalizes a nontrivial abelian subgroup of order prime to p.
π4 is the set of primes p such that a Sylow p-subgroup P has SCN3(P) nonempty but does not normalize a nontrivial abelian subgroup of order prime to p.
The proof is subdivided into several cases depending on which of these four classes the prime 2 belongs to, and also on an integer e, which is the largest integer for which there is an elementary abelian subgroup of rank e normalized by a nontrivial 2-subgroup intersecting it trivially.
Gives a general introduction, stating the main theorem and proving many preliminary lemmas.
characterizes the groups E2(3) and S4(3) (in Thompson's notation; these are the exceptional group G2(3) and the symplectic group Sp4(3)) which are not N-groups but whose characterizations are needed in the proof of the main theorem.
covers the case where 2∉π4. Theorem 11.2 shows that if 2∈π2 then the group is PSL2(q), M11, A7, U3(3), or PSL3(3). The possibility that 2∈π3 is ruled out by showing that any such group must be a C-group and using Suzuki's classification of C-groups to check that none of the groups found by Suzuki satisfy this condition.
and cover the cases when 2∈π4 and e≥3, or e=2. He shows that either G is a C-group so a Suzuki group, or satisfies his characterization of the groups E2(3) and S4(3) in his second paper, which are not N-groups.
covers the case when 2∈π4 and e=1, where the only possibilities are that G is a C-group or the Tits group.
Consequences
A minimal simple group is a non-cyclic simple group all of whose proper subgroups are solvable.
The complete list of minimal finite simple groups is given as follows
PSL2(2p), p a prime.
PSL2(3p), p an odd prime.
PSL2(p), p > 3 a prime congruent to 2 or 3 mod 5
Sz(2p), p an odd prime.
PSL3(3)
In other words a non-cyclic finite simple group must have a subquotient isomorphic to one of these groups.
References
Finite groups | N-group (finite group theory) | Mathematics | 898 |
18,142,318 | https://en.wikipedia.org/wiki/7-Spiroindanyloxymorphone | 7-Spiroindanyloxymorphone (SIOM) is a drug that is used in scientific research. It is a selective δ-opioid agonist. It is a derivative of oxymorphone.
References
4,5-Epoxymorphinans
Opioids
Delta-opioid receptor agonists
Hydroxyarenes
Tertiary alcohols
Ketones
Spiro compounds | 7-Spiroindanyloxymorphone | Chemistry | 85 |
40,515,402 | https://en.wikipedia.org/wiki/Lentinellus%20montanus | Lentinellus montanus is a species of agaric fungus in the family Auriscalpiaceae. It is found at high elevations in the Pacific Northwest region of North America, where it fruits singly or in clumps on decaying conifer wood.
Taxonomy
The species was officially described by American mycologist Orson K. Miller in 1965. The type collection was made in McCall, Idaho on June 26, 1963.
Description
The fruit bodies of Lentinellus montanus are sessile, meaning that they lack a stipe and grow directly on the substrate. The shell-shaped to fan-shaped cap measures in diameter. It is dark brown to red brown in color, except for the margins, which are light cinnamon to pale pinkish-buff. It is moist (but not sticky), somewhat hairy to shaggy in the center of the cap but smooth elsewhere. The gills are broad, somewhat distantly spaced, and interspersed with long lamellulae (gills that do not extend completely from the stipe to the cap margin). They have coarsely serrated edges, and a color ranging from white with purplish tints initially to buff in maturity. The tough flesh is light brown and 1–4 mm thick, with a mild to slightly aromatic odor and a mild to somewhat acrid taste.
Fruit bodies produce a cream to buff spore print. The spores are egg-shaped to roughly spherical, thick-walled, shell-shaped to fan-shaped, and measure 4.5–6.5 by 4–5 μm. Blunt spikes cover the spore surface. The basidia (spore-bearing cells) are club-shaped, four-spored, and measure 20–47 by 5.2–8 μm.
Like all species in its genus, it is inedible due to its bitterness.
Habitat and distribution
Lentinellus montanus is a white rot fungus. Its fruit bodies grow singly, or, more commonly, in clusters on decaying conifer wood at elevations between . Recorded tree substrates include Engelmann spruce (Picea engelmannii), Shasta red fir (Abies magnifica var. shastensis), subalpine fir (Abies lasiocarpa), and Pinus contorta. The fungus mycelium has also been found growing on fire wounds on living trees of Engelmann spruce and Lodgepole pine (Pinus contorta), where it attacks the springwood and causes small pockets of rot.
A snowbank mushroom, L. montanus fruits near melting snow banks, typically in the spring and early summer (May to July). The species occurs in northern and central Rocky Mountains east to the Cascade Range and south to Utah. Other states in which it has been recorded include Washington, Idaho, Montana, Colorado, Wyoming, and California.
Similar species
Lentinellus ursinus is similar.
References
External links
Russulales
Fungi described in 1965
Fungi of North America
Inedible fungi
Snowbank fungi
Fungus species | Lentinellus montanus | Biology | 620 |
54,534,627 | https://en.wikipedia.org/wiki/NGC%207070 | NGC 7070 is a spiral galaxy located about 100 million light-years away in the constellation of Grus. It has a close companion galaxy called NGC 7070A. NGC 7070 was discovered by astronomer John Herschel on September 5, 1834.
NGC 7070 is a member of a group of galaxies known as the NGC 7079 Group.
See also
NGC 7083
References
External links
Unbarred spiral galaxies
Grus (constellation)
7070
66869
Astronomical objects discovered in 1834
NGC 7079 Group | NGC 7070 | Astronomy | 106 |
69,149,793 | https://en.wikipedia.org/wiki/C/2021%20T4%20%28Lemmon%29 | C/2021 T4 (Lemmon) is a long period comet discovered by the Mount Lemmon Observatory on 7 October 2021. This passage through the planetary region of the Solar System will reduce the orbital period from millions of years to thousands of years.
It has been south of the celestial equator since October 2022. On 13 June it was 1.5 degrees from magnitude 2 Beta Ceti. Closest approach to Earth was on 20 July 2023 at a distance of . The next day it reached its southernmost declination, at -56 degrees. On 25 July it passed next to the globular cluster NGC 6397. It reached perihelion on 31 July 2023 at a solar distance of 1.48 AU. The comet brightened to around apparent magnitude 8.
References
External links
Non-periodic comets
Astronomical objects discovered in 2021
Oort cloud
Discoveries by MLS
Comets in 2021
Comets in 2023 | C/2021 T4 (Lemmon) | Astronomy | 184 |
7,023,870 | https://en.wikipedia.org/wiki/Sex%20strike | A sex strike (sex boycott), or more formally known as Lysistratic nonaction, is a method of nonviolent resistance in which one or more persons refrain from or refuse sex with partners until policy or social demands are met. It is a form of temporary sexual abstinence. Sex strikes have been used to protest many issues, from war to gang violence to policies.
The effectiveness of sex strikes is contested.
History
Ancient Greece
The most famous example of a sex strike in the arts is the Greek playwright Aristophanes' work Lysistrata, an anti-war comedy. The female characters in the play, led by the eponymous Lysistrata, withhold sex from their husbands as part of their strategy to end the Peloponnesian War.
Nigeria
Among the Igbo people of Nigeria, in pre-colonial times, the community of women periodically formed themselves into a Council, a kind of women's trade union. This was headed by the Agba Ekwe, 'the favoured one of the goddess Idemili and her earthly manifestation'. She carried her staff of authority and had the final word in public gatherings and assemblies. Central among her tasks was to ensure men's good behaviour, punishing male attempts at harassment or abuse. What men most feared was the council's power of strike action. According to Ifi Amadiume, an Igbo anthropologist: "The strongest weapon the Council had and used against the men was the right to order mass strikes and demonstrations by all women. When ordered to strike, women refused to perform their expected duties and roles, including all domestic, sexual and maternal services. They would leave the town en masse, carrying only suckling babies. If angry enough, they were known to attack any men they met."
World history and prehistory
Citing similar examples of women's strike action in hunter-gatherer and other precolonial traditions around the world, some anthropologists argue that it was thanks to solidarity of this kind—especially collective resistance to the possibility of rape—that language, culture, and religion became established in our species in the first instance. This controversial hypothesis is known as the "Female Cosmetic Coalitions", "Lysistrata", or "sex strike" theory of human origins.
Modern times
Africa
Kenya
In April 2009 a group of Kenyan women organised a week-long sex strike aimed at politicians, encouraging the wives of the president and prime minister to join in too, and offering to pay prostitutes for lost earnings if they joined in.
Liberia
In 2003 Leymah Gbowee and the Women of Liberia Mass Action for Peace organized nonviolence protests that included suggesting a sex strike, though this was not actually carried out. Their actions led to peace in Liberia after a 14‑year civil war and the election of Ellen Johnson Sirleaf, country's first female head of state. Leymah Gbowee was awarded the 2011 Nobel Peace Prize "for her non-violent struggle for the safety of women and for women's rights to full participation in peace-building work."
South Sudan
In October 2014, Pricilla Nanyang, a politician in South Sudan, coordinated a meeting of women peace activists in Juba "to advance the cause of peace, healing and reconciliation." Attendees issued a statement which called on women of South Sudan "to deny their husbands conjugal rights until they ensure that peace returns."
Togo
In 2012, inspired by the 2003 Liberian sex strike, the Togolese opposition coalition "Let's Save Togo" asked women to abstain from sex for a week as a protest against President Faure Gnassingbé, whose family has been in power for more than 45 years. The strike aimed to "motivate men who are not involved in the political movement to pursue its goals". Opposition leader Isabelle Ameganvi views it as a possible "weapon of the battle" to achieve political change.
Elsewhere
Colombia
In October 1997, the chief of the Military of Colombia, General Manuel Bonnet publicly called for a sex strike among the wives and girlfriends of the Colombian left-wing guerrillas, drug traffickers, and paramilitaries as part of a strategy—along with diplomacy—to achieve a ceasefire. Also the mayor of Bogota, Antanas Mockus, declared the capital a women-only zone for one night, suggesting men to stay at home to reflect on violence. The guerrillas ridiculed the initiatives, pointing at the fact that there were more than 2,000 women in their army. In the end the ceasefire was achieved, but lasted only a short time.
In September 2006 dozens of wives and girlfriends of gang members from Pereira, Colombia, started a sex strike called La huelga de las piernas cruzadas ("the strike of crossed legs") to curb gang violence, in response to 480 deaths due to gang violence in the coffee region. According to spokeswoman Jennifer Bayer, the specific target of the strike was to force gang members to turn in their weapons in compliance with the law. According to them, many gang members were involved in violent crime for status and sexual attractiveness, and the strike sent the message that refusing to turn in the guns was not sexy. In 2010 the city's murder rate saw the steepest decline in Colombia, down by 26.5%.
In June 2011, women organized in the so-called Crossed Legs Movement in the secluded town of Barbacoas in southwestern Colombia, started a sex strike to pressure the government to repair the road connecting Barbacoas and its neighboring towns and cities. They declared that if the men of the town were not going to demand action, they would refuse to have sex with them. The men of Barbacoas showed no support at the beginning of the campaign, but they soon joined in the protest campaign. After 112 days strike in October 2011, the Colombian government promised action on road repairs. Construction ensued and the strike ended.
Naples, Italy
In the build-up to New Year's Eve in 2008, hundreds of Neapolitan women pledged to make their husbands and lovers "sleep on the sofa" unless they took action to prevent fireworks from causing serious injuries.
The Philippines
During the summer of 2011, women in rural Mindanao imposed a several-week-long sex strike in an attempt to end fighting between their two villages.
United States of America
In 2019, Georgia governor, Brian Kemp (R), signed House Bill (HB) 481 into law. It was immediately blocked by a lawsuit. HB 481 criminalizes most abortions after six weeks and adds a “fetal personhood” language. This language changes the definition of a “natural person” to include an unborn child at any stage of development in the womb. This law has been nicknamed a “heartbeat bill” because HB 481 states that no abortion will be performed if the physician determines that they detect a human heartbeat.
In response to this bill's passage, actress and #MeToo activist, Alyssa Milano and Waleisah Wilson wrote an opinion editorial for CNN and went to Twitter to call for a sex strike until the policy was repealed. In the tweet, Milano calls on women to join her sex strike until women “have legal control over [their] own bodies” because women cannot risk a pregnancy under this new bill. In her CNN opinion piece, Milano states that there are similar bills to the one in Georgia and that the single purpose of them is to make it up to the Supreme Court, forcing them reconsider Roe v. Wade (1973). In this opinion piece, Milano discusses the history of Lysistratic protest, calls on people who can become pregnant to conduct a sex strike, and pay attention to current events. Milano encourages a sex strike in addition to other efforts.
In entertainment
Lysistrata
Absurdistan (film)
Chi-Raq (film)
See also
2021 Minas Gerais prostitute strike
Matriarchy
Menstrual synchrony
Occupation of Saint-Nizier church by Lyon prostitutes
Reproductive synchrony
Sex/Work Strike
Women's strike (disambiguation)
Female cosmetic coalitions
References
External links
Sexual abstinence
Human sexuality
Strikes (protest)
Protest tactics
Nonviolence
Feminism and sexuality
Feminist terminology
Women's strikes | Sex strike | Biology | 1,683 |
7,247,551 | https://en.wikipedia.org/wiki/PH%2075 | PH 75 was a military development program in France aimed at designing a nuclear-powered amphibious assault ship during the 1970s. Design work was never completed by the time the project was cancelled in 1981.
History
The role of providing air support for amphibious operations in the French Navy was left to the aging Arromanches (R 95), a World War II-era light carrier. PH 75 was envisioned as the replacement for the Arromanches. Nuclear propulsion was selected to allow the vessel to operate with fewer support vessels and at longer ranges. Other roles were added to the program including command, rescue, and anti-submarine warfare. Early plans were for completion of the first unit by 1981, but this proved unobtainable, and after several delays, the project was finally cancelled.
France instead chose to pursue a conventionally powered vessel to fulfill this role, termed a power projection ship, resulting in the development of the Mistral class which entered service in 2005. Meanwhile, France also developed a nuclear-powered aircraft carrier, the Charles de Gaulle.
See also
Mistral-class amphibious assault ship
List of aircraft carriers
References
Proposed aircraft carriers
Amphibious warfare vessel classes
Helicopter carrier classes
Amphibious warfare vessels of France
Aircraft carriers of France
Nuclear-powered ships of the French Navy
Abandoned military projects of France
1981 disestablishments in France | PH 75 | Engineering | 267 |
960,668 | https://en.wikipedia.org/wiki/Ernst%20Leonard%20Lindel%C3%B6f | Ernst Leonard Lindelöf (; 7 March 1870 – 4 June 1946) was a Finnish mathematician, who made contributions in real analysis, complex analysis and topology. Lindelöf spaces are named after him. He was the son of mathematician Lorenz Leonard Lindelöf and brother of the philologist .
He was secretary of the Finnish Society of Science and Letters (societas scientiarum Fennica) in its centenary year, 1938.
Biography
Lindelöf studied at the University of Helsinki, where he completed his PhD in 1893, became a docent in 1895 and professor of Mathematics in 1903. He was a member of the Finnish Society of Sciences and Letters.
In addition to working in a number of different mathematical domains including complex analysis, conformal mappings, topology, ordinary differential equations and the gamma function, Lindelöf promoted the study of the history of Finnish mathematics. He is known for the Picard–Lindelöf theorem on differential equations and the Phragmén–Lindelöf principle, one of several refinements of the maximum modulus principle that he proved in complex function theory. He was the PhD supervisor for Lars Ahlfors at the University of Helsinki.
Selected bibliography
Le calcul des résidus et ses applications à la théorie des fonctions (Paris, 1905)Mémoire sur la théorie des fonctions entières d'ordre fini ("Acta societatis scientiarum fennicae" 31, 1903)With Lars Edvard Phragmén: "Sur une extension d'un principe classique de l'analyse et sur quelques propriétés des fonctions monogènes dans le voisinage d'un point singulier", in: Acta Mathematica'' 31, 1908.
References
External links
1870 births
1946 deaths
Scientists from Helsinki
20th-century Finnish mathematicians
Topologists
19th-century Finnish mathematicians
Academic staff of the University of Helsinki
Members of the Royal Society of Sciences in Uppsala
Mathematicians from the Russian Empire | Ernst Leonard Lindelöf | Mathematics | 417 |
65,924,162 | https://en.wikipedia.org/wiki/Chalk%20paint | Chalk paint is a water-based, decorative paint invented by Annie Sloan which may be applied over almost any surface. It requires very little preparation and needs a topcoat to avoid flaking. Chalk paints are also used by utility companies to mark road surfaces.
Description
Chalk paint is a water-based, decorative paint that results in a chalky, matte finish. The paint consists of a fine powder such as plaster of Paris or calcium carbonate, mixed with water. Commercial acrylic paint is added as a colorant.
Origins
Artist Annie Sloan invented chalk paint in 1990 and registered Chalk Paint as a trademark. There are similar products on the retail market and many online recipes.
Uses
This paint is intended for use on furniture and other home décor to achieve a specific result, such as shabby chic, and vintage. When applying chalk paint, an item's surface should be clean, and priming is only advised when working with a white chalk paint. It is also advised to use two coats of lacquer to make sure the intended material for painting gets full coverage. Sanding or stripping previous layers is not needed. Interior and exterior surfaces including metal, wood, glass, concrete, plaster, and fabric, may be painted with chalk paint.
Chalk paint may be applied with a brush, roller, or spray gun. The paint should be applied in thin layers and will typically dry within two hours. A topcoat sealer, such as wax or lacquer, should be applied to avoid the flaking of the chalk paint. The topcoats may enhance the decorative characteristics.
Sprayable chalk paint is used by public works engineers to mark the location of utility pipes and cables on sidewalks, as an environmentally safe substance which can be easily removed when the work is complete. Others have used it to mark potholes in roads, and to spray graffiti that can be washed off.
Types
The components that are included in the chalk paint, and the type of surface that will be painted, determine the composition and structure of the layer to be formed. All chalk paint has a water basis. The type of paint depends on the additives used. There are:
resinous. Contains natural and/or synthetic resins. Silicates are additionally introduced into the composition;
milk. Casein is used as an additional component;
oil. The additive is linseed oil.
Factory-made chalk compositions may be available in various forms. Manufacturers offer spray cans and tins. The form of release determines the order of application of the composition and its possible area of use. For example, unlike conventional chalk paint, which requires application to the surface with a brush or roller, chalk spray paint allows you to quickly apply it by spraying. Chalk paints can also be divided by the texture of the coating to be formed:
smooth, which can then be used for drawing;
embossed, having a texture. Acrylic, silicone, or latex (resinous) emulsion is used as a base for creating textured chalk paint.
Sometimes a certain amount of metallic powder is added to the latex emulsion. This makes it possible to give magnetic properties to the formed layer. Such paint can be used in the production of slateboards.
References
Paints
Paint | Chalk paint | Chemistry | 655 |
33,335,576 | https://en.wikipedia.org/wiki/Torque-to-yield%20fastener | A torque to yield fastener (TTY) or stretch Bolt is a fastener which is torqued beyond the state of elasticity and therefore undergoes plastic deformation, causing it to become permanently elongated.
Fastener
Torquing a fastener close to its yield point results in a residual axial preloading of the fastener which, depending on service conditions, can significantly increase the fatigue life of the fastener. When the applied service load doesn't exceed the clamping force of the fastener, the strain of the fastener will be lower than when the preloading is smaller than the applied load. It is therefore beneficial in high-frequency high-load situations with a higher risk of fatigue related failure, like a bolted down cylinder head, to use torque to yield bolts.
The torque applied to the fastener must be determined such that it does not contribute to a service condition where the fastener enters a low-cycle fatigue regime. In general, the use of torque-to-yield fasteners is deprecated except in cases where the materials and structures comprising the entire assembly are certified to be within tolerances.
Advantage: The service lifetime can be predicted, and regular maintenance intervals determined with a tolerable degree of certainty.
Disadvantage: TTY hardware must be assumed to be compromised and must be removed from service if subsequently loosened, tightened, or damaged.
References
Fasteners | Torque-to-yield fastener | Engineering | 282 |
62,276,942 | https://en.wikipedia.org/wiki/Finish%20%28detergent%29 | Finish is the brand name of a range of dishwasher detergent and cleaning products sold by the consumer products manufacturer Reckitt. The tablets, based on the original product, contain surfactants which counteract water hardness and break down foods containing starches and proteins, and remove bleachable stains and produce enzymes and foams. The product is specially designed for dishwashers. Prior to 2009, the product was known as Electrasol in North America, and as Calgonit in some European countries.
History
In the early 1950s, the increased use of moulded plastic dinnerware posed a number of problems. The Finish brand was created in 1953 by the US company Economics Laboratory (now Ecolab). Taking advantage of research into the needs of the dairy and food industry, the company launched two new products for the household dishwashing machine in 1953: mass-market product Electrasol, and premium product Finish. Later, in 1969, they introduced the first biological powder.
J. A. Benckiser (later Reckitt Benckiser) acquired the Consumer Products division of Ecolab Inc. in 1987. In 1995, the first two-ply powder tablet was introduced, in 1999 the red Powerball capsule, in 2008, the Finish Quantum and the first three-chamber moulded capsule. Circa 2009, all Electrasol products were rebranded under Finish label.
See also
List of renamed products
References
External links
Detergents
Cleaning product brands
Cleaning product components
Cleaning products
American brands
Reckitt brands
Procter & Gamble brands
Products introduced in 1953 | Finish (detergent) | Chemistry,Technology | 320 |
43,148,379 | https://en.wikipedia.org/wiki/Tower%20climber | A tower climber specializes in maintenance, installation, and decommissioning of cellular and radio tower components such as coaxial cable, antennas, radios, fiber-optic cable and broadcast equipment for cell phones, television, radio, etc.
Description
Tower climbers perform routine inspections and tests on broadcasting towers, and may also be called upon to perform repairs and to provide input when plans for new equipment are being developed.
Along with the installers of the tower antennas, other crews climb the towers to perform condition checks of the towers, guy lines and lighting systems. One of the most demanding aspects of many tower climber jobs is hauling materials and tools up to the proper installation height on the tower. In most cases, the climber scales the tower to the desired height and lowers a rope to a ground crew member who then ties it to a needed part on the ground. The tower worker then pulls the piece up and secures the rope before installing the part onto the tower.
Hazards
Tower climbers may be injured or killed by falling objects, structural collapses and equipment failures. Some of the more frequently encountered hazards include falls from great heights; electrical hazards; hazards associated with hoisting personnel and equipment with base-mounted drum hoists; inclement weather; and structural collapse of towers.
United States
Working on cellphone towers is the deadliest job in the United States, according to a trade publication, and it has been claimed that the tower climbing industry experiences 10 times more death casualties than the construction workers. There were 50 - 100 deaths from falls from communication towers between 2003 and 2011. The head of the Occupational Safety and Health Administration (OSHA) once called tower climbing “the most dangerous job in America.”
References
Construction trades workers
Wireless technology people | Tower climber | Technology | 355 |
20,555,335 | https://en.wikipedia.org/wiki/Atriplex%20watsonii | Atriplex watsonii is a species of saltbush known by the common name Watson's saltbush, or Watson's orach. It is native to the coastline of California and Baja California, where it grows in coastal areas with saline soils, such as salt marshes and beach scrub, with other halophytes such as saltgrass. It extends inland in the Los Angeles Basin, and along the Santa Ana River.
Description
This is a gray-green to whitish perennial herb with tangled slender stems under a meter in length. It grows in mats up to 3 meters wide. The thick, fleshy, crusty leaves are up to 2.5 centimeters long and generally oval in shape.
The plant is dioecious, with individuals bearing either male or female flowers. The male flowers grow in clusters or long spikes, and the female flowers can be found in small clusters in the leaf axils.
The plant is part of the Chenopodiaceae family
References
External links
Calflora Database: Atriplex watsonii (Matscale, Watson's saltbush)
Jepson Manual eFlora (TJM2) treatment of Atriplex watsonii
USDA Plants Profile for Atriplex watsonii (Watson's saltbush)
Flora of North America
UC Photos gallery: Atriplex watsonii
watsonii
Halophytes
Flora of California
Flora of Baja California
Natural history of the California chaparral and woodlands
Natural history of the Channel Islands of California
Natural history of the Santa Monica Mountains
Salt marsh plants
Dioecious plants
Flora without expected TNC conservation status | Atriplex watsonii | Chemistry | 323 |
66,026,415 | https://en.wikipedia.org/wiki/Modern%20Quantum%20Mechanics | Modern Quantum Mechanics, often called Sakurai or Sakurai and Napolitano, is a standard graduate-level quantum mechanics textbook written originally by J. J. Sakurai and edited by San Fu Tuan in 1985, with later editions coauthored by Jim Napolitano. Sakurai died in 1982 before he could finish the textbook and both the first edition of the book, published in 1985 by Benjamin Cummings, and the revised edition of 1994, published by Addison-Wesley, were edited and completed by Tuan posthumously. The book was updated by Napolitano and released two later editions. The second edition was initially published by Addison-Wesley in 2010 and rereleased as an eBook by Cambridge University Press, who released a third edition in 2020.
Table of contents (3rd edition)
Prefaces
Chapter 1: Fundamental Concepts
Chapter 2: Quantum Dynamics
Chapter 3: Theory of Angular Momentum
Chapter 4: Symmetry in Quantum Mechanics
Chapter 5: Approximation Methods
Chapter 6: Scattering Theory
Chapter 7: Identical Particles
Chapter 8: Relativistic Quantum Mechanics
Appendix A: Electromagnetic Units
Appendix B: Elementary Solutions to Schrödinger's Wave Equation
Appendix C: Hamiltonian for a Charge in an Electromagnetic Field
Appendix D: Proof of the Angular-Momentum Rule (3.358)
Appendix E: Finding Clebsch-Gordan Coefficients
Appendix F: Notes on Complex Variables
Bibliography
Index
Reception
Early editions of the book have received several reviews. It is a standard textbook on the subject and is recommended in other works on the subject, it has inspired other textbooks on the subject, and it is used as a point of comparison in book reviews. Along with Griffith's Introduction to Quantum Mechanics, the book was also analyzed in a review of the "Philosophical Standpoints of Textbooks in Quantum Mechanics" in June 2020.
Publication history
(hardcover)
(hardcover)
(eBook)
(hardcover)
(eBook)
See also
Introduction to Quantum Mechanics, an undergraduate text by David J. Griffiths
List of textbooks on classical mechanics and quantum mechanics
References
External links
Publisher's website for the 2nd edition
Publisher's website for the 3rd edition
Book in the Internet Archive
Physics textbooks
1985 non-fiction books
1994 non-fiction books
2020 non-fiction books
Quantum mechanics | Modern Quantum Mechanics | Physics | 446 |
7,895,070 | https://en.wikipedia.org/wiki/K%20correction | K correction converts measurements of astronomical objects into their respective rest frames. The correction acts on that object's observed magnitude (or equivalently, its flux). Because astronomical observations often measure through a single filter or bandpass, observers only measure a fraction of the total spectrum, redshifted into the frame of the observer. For example, to compare measurements of stars at different redshifts viewed through a red filter, one must estimate K corrections to these measurements in order to make comparisons. If one could measure all wavelengths of light from an object (a bolometric flux), a K correction would not be required, nor would it be required if one could measure the light emitted in an emission line.
Carl Wilhelm Wirtz (1918), who referred to the correction as a Konstanten k (German for "constant") - correction dealing with the effects of redshift of in his work on Nebula. English-speaking claim for the origin of the term "K correction" is Edwin Hubble, who supposedly arbitrarily chose to represent the reduction factor in magnitude due to this same effect and who may not have been aware / given credit to the earlier work.
The K-correction can be defined as follows
I.E. the adjustment to the standard relationship between absolute and apparent magnitude required to correct for the redshift effect. Here, DL is the luminosity distance measured in parsecs.
The exact nature of the calculation that needs to be applied in order to perform a K correction depends upon the type of filter used to make the observation and the shape of the object's spectrum. If multi-color photometric measurements are available for a given object thus defining its spectral energy distribution (SED), K corrections then can be computed by fitting it against a theoretical or empirical SED template. It has been shown that K corrections in many frequently used broad-band filters for low-redshift galaxies can be precisely approximated using two-dimensional polynomials as functions of a redshift and one observed color. This approach is implemented in the K corrections calculator web-service.
References
External links
Basic concept of obtaining K corrections
Astrophysics
Doppler effects | K correction | Physics,Astronomy | 448 |
343,400 | https://en.wikipedia.org/wiki/Simple%20theorems%20in%20the%20algebra%20of%20sets | The simple theorems in the algebra of sets are some of the elementary properties of the algebra of union (infix operator: ∪), intersection (infix operator: ∩), and set complement (postfix ') of sets.
These properties assume the existence of at least two sets: a given universal set, denoted U, and the empty set, denoted {}. The algebra of sets describes the properties of all possible subsets of U, called the power set of U and denoted P(U). P(U) is assumed closed under union, intersection, and set complement. The algebra of sets is an interpretation or model of Boolean algebra, with union, intersection, set complement, U, and {} interpreting Boolean sum, product, complement, 1, and 0, respectively.
The properties below are stated without proof, but can be derived from a small number of properties taken as axioms. A "*" follows the algebra of sets interpretation of Huntington's (1904) classic postulate set for Boolean algebra. These properties can be visualized with Venn diagrams. They also follow from the fact that P(U) is a Boolean lattice. The properties followed by "L" interpret the lattice axioms.
Elementary discrete mathematics courses sometimes leave students with the impression that the subject matter of set theory is no more than these properties. For more about elementary set theory, see set, set theory, algebra of sets, and naive set theory. For an introduction to set theory at a higher level, see also axiomatic set theory, cardinal number, ordinal number, Cantor–Bernstein–Schroeder theorem, Cantor's diagonal argument, Cantor's first uncountability proof, Cantor's theorem, well-ordering theorem, axiom of choice, and Zorn's lemma.
The properties below include a defined binary operation, relative complement, denoted by the infix operator "\". The "relative complement of A in B," denoted B \A, is defined as (A ∪) and as ∩B.
PROPOSITION 1. For any U and any subset A of U:
{} = U;
= {};
A \ {} = A;
{} \ A = {};
A ∩ {} = {};
A ∪ {} = A; *
A ∩ U = A; *
A ∪ U = U;
∪ A = U; *
∩ A = {}; *
A \ A = {};
U \ A = ;
A \ U = {};
= A;
A ∩ A = A;
A ∪ A = A.
PROPOSITION 2. For any sets A, B, and C:
A ∩ B = B ∩ A; * L
A ∪ B = B ∪ A; * L
A ∪ (A ∩ B) = A; L
A ∩ (A ∪ B) = A; L
(A ∪ B) \ A = B \ A;
A ∩ B = {} if and only if B \ A = B;
( ∪ B) ∪ ( ∪ ) = A;
(A ∩ B) ∩ C = A ∩ (B ∩ C); L
(A ∪ B) ∪ C = A ∪ (B ∪ C); L
C \ (A ∩ B) = (C \ A) ∪ (C \ B);
C \ (A ∪ B) = (C \ A) ∩ (C \ B);
C \ (B \ A) = (C \ B) ∪(C ∩ A);
(B \ A) ∩ C = (B ∩ C) \ A = B ∩ (C \ A);
(B \ A) ∪ C = (B ∪ C) \ (A \ C).
The distributive laws:
A ∩ (B ∪ C) = (A ∩ B) ∪ (A ∩ C); *
A ∪ (B ∩ C) = (A ∪ B) ∩ (A ∪ C). *
PROPOSITION 3. Some properties of ⊆:
A ⊆ B if and only if A ∩ B = A;
A ⊆ B if and only if A ∪ B = B;
A ⊆ B if and only if ⊆ ;
A ⊆ B if and only if A \ B = {};
A ∩ B ⊆ A ⊆ A ∪ B.
See also
References
Edward Huntington (1904) "Sets of independent postulates for the algebra of logic," Transactions of the American Mathematical Society 5: 288-309.
Whitesitt, J. E. (1961) Boolean Algebra and Its Applications. Addison-Wesley. Dover reprint, 1999. | Simple theorems in the algebra of sets | Mathematics | 951 |
60,125,052 | https://en.wikipedia.org/wiki/NGC%201160 | NGC 1160 is a spiral galaxy approximately 116 million light-years away from Earth in the constellation of Perseus. It was discovered, along with NGC 1161, by English astronomer William Herschel on October 7, 1784.
NGC 1160 forms a visual pair with the galaxy NGC 1161. Both galaxies are located between the Local and Perseus superclusters.
See also
Spiral galaxy
List of NGC objects (1001–2000)
Perseus (constellation)
References
External links
SEDS
Spiral galaxies
Perseus (constellation)
1160
11403
Astronomical objects discovered in 1784
Discoveries by John Herschel | NGC 1160 | Astronomy | 126 |
36,958,743 | https://en.wikipedia.org/wiki/14%20Comae%20Berenices | 14 Comae Berenices is a single star in the northern constellation of Coma Berenices, and is the second brightest member of the Coma Star Cluster. It is a faint star but visible to the naked eye with an apparent visual magnitude of 4.95. Parallax measurements place the star at a distance of about 266 light years.
The spectrum of this star is peculiar and it has been assigned a number of different stellar classifications: A5, F0p, , F0 vp, , , F1 IV, and . Abt & Morrell (1995) designated this a Lambda Boötis star but this was later refuted. No surface magnetic field has been detected on 14 Comae Bernices.
14 Comae Berenices is a well-known shell star with a high rate of spin, showing a projected rotational velocity of 226 km/s. This is giving the star an oblate shape with an equatorial bulge that is 12% larger than the polar radius. It is radiating 76 times the Sun's luminosity from its photosphere at an effective temperature of 7,300 K.
References
F-type stars
Shell stars
Ap stars
Coma Berenices
BD+28 2115
Comae Berenices, 14
108283
060697
4733 | 14 Comae Berenices | Astronomy | 262 |
24,564,752 | https://en.wikipedia.org/wiki/Naval%20flag%20signalling | Naval flag signalling covers various forms of flag signalling, such as semaphore or flaghoist, used by various navies; distinguished from maritime flag signalling by merchant or other non-naval vessels or flags used for identification.
History
Naval flag signalling undoubtedly developed in antiquity in order to coordinate naval action of multiple vessels. In the Peloponnesian War (431 – 401 BCE) squadrons of Athenian galleys were described by Thucydides as engaging in coordinated maneuvers which would have required some kind of communication; there is no record of how such communication was done but flags would have been the most likely method.
Flags have long been used to identify a ship's owner or nationality, or the commander of a squadron. But the use of flags for signalling messages long remained primitive, as indicated by the 1530 instruction that when the Admiral
doth shote of a pece of Ordnance, and set up his Banner of Council on Starrborde bottocke of his Shippe, everie shipps capten shall with spede go aborde the Admyrall to know his will.
Several wars with the Dutch in the 17th century prompted the English to issue instructions for the conduct of particular fleets, such as (in 1673) the Duke of York's "Instructions for the better Ordering of His Majesties Fleet in Sayling". Signals were primitive and rather ad hoc ("As soon as the Admiral shall loose his fore-top and fire a gun..."), and generally a one-way communication system, as only flagships carried a complete set of flags. In 1790 Admiral Lord Howe issued a new signal book for a numerary system using numeral flags to signal a number; the number, not the mast from which the flags flew, indicated the message. Other admirals tried various systems; it was not until 1799 that the Admiralty issued a standardized signal code system for the entire Royal Navy. This was limited to only the signals listed in the Signal-Book. In 1800 Captain Sir Home Popham devised a means of extending this: signals made with a special "Telegraph" flag refererred to a separate dictionary of numbered words and phrases. A similar system was devised by Captain Marryat in 1817 "for the use of vessels employed in the merchant service".
Marryat's Code of Signals and various competitors have been supplanted by the International Code of Signals (ICS) for general maritime use. Most navies now use the flags of the ICS for 26 letters A through Z, sometimes augmenting them with additional flags for other national characters. But they retain additional flags for naval usage (such as related to maneuvering or status), and use their own codes. E.g., in the ICS the single flag Mike means the vessel is stopped; in the U. S. Navy it means the duty medical officer is on board.
Flaghoist was the only way ships could signal prior to the advent of radio and blinking light. Even now it is often the preferred method of signalling messages of local significance. A radio message that "[ship's call sign] is fueling, everyone stand clear" is incomplete without information as to where the ship is; it is also distracting for many remote parties that are not affected, and congests the radio channel. Flying the Bravo flag is complete information: "danger, stand clear of here". It also communicates to all local parties, including personnel in the vicinity, or in passing small boats that do not have radios. Similarly, a radio message to the effect "this is the admiral, follow me" could lead to disaster if anyone mistook which ship the admiral is on.
Flag examples
Numerals
Substitutes
These flags indicate a repeat of the first, second, etc., flag in that hoist.
Sample flag meanings
Despite the NATO sharing the same alphabetic flags as the International Code of Signals, the meanings are not shared between the codes. Furthermore, the NATO code uses a number of special flags which alter the meaning of the hoist. All below signals have been taken from a 2003 unclassified NATO codebook.
See also
Bravo Zulu
Bunting tosser
England expects that every man will do his duty (a famous flag signal).
Maritime flag signalling
Semaphore
Signal lamp
International Code of Signals
Russian Navy Code of Signals
Japanese Navy Signal Flags
Notes
Sources
External links
Royal Navy Signal Flags and Pendants
Sea Flags (Joseph McMillan)
Historic Modes of Naval Communication (Captain Howeth)
Flag Signalling at Sea (Captain Barrie Kent)
NATO flags (Flags of the World)
Signal flags of the Imperial Japanese Navy (World War II).
Russian signalling flags.
Signalman 3 & 2 manual used to train U.S. Navy signalmen; detailed coverage of procedure.
Emergency communication
Military communications
Signalling
Naval warfare
Signal flags | Naval flag signalling | Engineering | 982 |
22,719,936 | https://en.wikipedia.org/wiki/Baryon%20acoustic%20oscillations | In cosmology, baryon acoustic oscillations (BAO) are fluctuations in the density of the visible baryonic matter (normal matter) of the universe, caused by acoustic density waves in the primordial plasma of the early universe. In the same way that supernovae provide a "standard candle" for astronomical observations, BAO matter clustering provides a "standard ruler" for length scale in cosmology.
The length of this standard ruler is given by the maximum distance the acoustic waves could travel in the primordial plasma before the plasma cooled to the point where it became neutral atoms (the epoch of recombination), which stopped the expansion of the plasma density waves, "freezing" them into place. The length of this standard ruler (≈490 million light years in today's universe) can be measured by looking at the large scale structure of matter using astronomical surveys. BAO measurements help cosmologists understand more about the nature of dark energy (which causes the accelerating expansion of the universe) by constraining cosmological parameters.
Early universe
The early universe consisted of a hot, dense plasma of electrons and baryons (which include protons and neutrons). Photons (light particles) travelling in this universe were essentially trapped, unable to travel for any considerable distance before interacting with the plasma via Thomson scattering. The average distance which a photon could travel before interacting with the plasma is known as the mean free path of the photon. As the universe expanded, the plasma cooled to below 3000 K—a low enough energy such that the electrons and protons in the plasma could combine to form neutral hydrogen atoms. This recombination happened when the universe was around 379,000 years old, or at a redshift of . At this age, the size of BAO bubbles were 450,000 light-years (0.14 Mpc) in radius (490 million light-years today divided by z = 1089). Photons interact to a much lesser degree with neutral matter, and therefore at recombination the universe became transparent to photons, allowing them to decouple from the matter and free-stream through the universe. The cosmic microwave background (CMB) radiation is light that was scattered just before, and emitted by, recombination, now seen with our telescopes as radio waves all over the sky since it is red-shifted. Therefore, when looking at, for example, Wilkinson Microwave Anisotropy Probe (WMAP) data, one is basically looking back in time to see an image of the universe when it was only 379,000 years old.
WMAP indicates (Figure 1) a smooth, homogeneous universe with density anisotropies of 10 parts per million. However, there are large structures and density fluctuations in the present universe. Galaxies, for instance, are a million times more dense than the universe's mean density. The current belief is that the universe was built in a bottom-up fashion, meaning that the small anisotropies of the early universe acted as gravitational seeds for the structure observed today. Overdense regions attract more matter, whereas underdense regions attract less, and thus these small anisotropies, seen in the CMB, became the large scale structures in the universe today.
Cosmic sound
Imagine an overdense region of the primordial plasma. While this region of overdensity gravitationally attracts matter towards it, the heat of photon-matter interactions creates a large amount of outward pressure. These counteracting forces of gravity and pressure created oscillations, comparable to sound waves created in air by pressure differences.
This overdense region contains dark matter, baryons and photons. The pressure results in spherical sound waves of both baryons and photons moving with a speed slightly over half the speed of light outwards from the overdensity. The dark matter interacts only gravitationally, and so it stays at the center of the sound wave, the origin of the overdensity. Before decoupling, the photons and baryons moved outwards together. After decoupling the photons were no longer interacting with the baryonic matter and they diffused away. That relieved the pressure on the system, leaving behind shells of baryonic matter. Out of all those shells, representing different sound waves wavelengths, the resonant shell corresponds to the first one as it is that shell that travels the same distance for all overdensities before decoupling. This radius is often referred to as the sound horizon.
Without the photo-baryon pressure driving the system outwards, the only remaining force on the baryons was gravitational. Therefore, the baryons and dark matter (left behind at the center of the perturbation) formed a configuration which included overdensities of matter both at the original site of the anisotropy and in the shell at the sound horizon for that anisotropy. Such anisotropies eventually became the ripples in matter density that would form galaxies.
Therefore, one would expect to see a greater number of galaxy pairs separated by the sound horizon distance scale than by other length scales. This particular configuration of matter occurred at each anisotropy in the early universe, and therefore the universe is not composed of one sound ripple, but many overlapping ripples. As an analogy, imagine dropping many pebbles into a pond and watching the resulting wave patterns in the water. It is not possible to observe this preferred separation of galaxies on the sound horizon scale by eye, but one can measure this artifact statistically by looking at the separations of large numbers of galaxies.
Standard ruler
The physics of the propagation of the baryon waves in the early universe is fairly simple; as a result cosmologists can predict the size of the sound horizon at the time of recombination. In addition the CMB provides a measurement of this scale to high accuracy. However, in the time between recombination and present day, the universe has been expanding. This expansion is well supported by observations and is one of the foundations of the Big Bang Model. In the late 1990s, observations of supernovae determined that not only is the universe expanding, it is expanding at an increasing rate. A better understanding of the acceleration of the universe, or dark energy, has become one of the most important questions in cosmology today. In order to understand the nature of the dark energy, it is important to have a variety of ways of measuring the acceleration. BAO can add to the body of knowledge about this acceleration by comparing observations of the sound horizon today (using clustering of galaxies) to that of the sound horizon at the time of recombination (using the CMB). Thus BAO provides a measuring stick with which to better understand the nature of the acceleration, completely independent from the supernova technique.
BAO signal in the Sloan Digital Sky Survey
The Sloan Digital Sky Survey (SDSS) is a major multi-spectral imaging and spectroscopic redshift survey using the dedicated 2.5-metre wide-angle SDSS optical telescope at Apache Point Observatory in New Mexico. The goal of this five-year survey was to take images and spectra of millions of celestial objects. The result of compiling the SDSS data is a three-dimensional map of objects in the nearby universe: the SDSS catalog. The SDSS catalog provides a picture of the distribution of matter in a large enough portion of the universe that one can search for a BAO signal by noting whether there is a statistically significant overabundance of galaxies separated by the predicted sound horizon distance.
The SDSS team looked at a sample of 46,748 luminous red galaxies (LRGs), over 3,816 square-degrees of sky (approximately five billion light years in diameter) and out to a redshift of . They analyzed the clustering of these galaxies by calculating a two-point correlation function on the data. The correlation function (ξ) is a function of comoving galaxy separation distance (s) and describes the probability that one galaxy will be found within a given distance of another.
One would expect a high correlation of galaxies at small separation distances (due to the clumpy nature of galaxy formation) and a low correlation at large separation distances. The BAO signal would show up as a bump in the correlation function at a comoving separation equal to the sound horizon. This signal was detected by the SDSS team in 2005. SDSS confirmed the WMAP results that the sound horizon is ~ in today's universe.
In 2023 astronomers using the SDSS catalog as well as the cosmicflow-4 catalog claimed to have found evidence of an individual BAO bubble with a radius containing some of largest structures known – the Boötes supercluster, the Sloan Great Wall, CfA2 Great Wall, and the Hercules–Corona Borealis Great Wall – which they named Ho'oleilana.
Detection in other galaxy surveys
The 2dFGRS collaboration and the SDSS collaboration reported a detection of the BAO signal in the power spectrum at around the same time in 2005. Both teams are credited and recognized for the discovery by the community as evidenced by the 2014 Shaw Prize in Astronomy which was awarded to both groups. Since then, further detections have been reported in the 6dF Galaxy Survey (6dFGS) in 2011, WiggleZ in 2011 and BOSS in 2012.
Dark energy formalism
BAO constraints on dark energy parameters
The BAO in the radial and transverse directions provide measurements of the Hubble parameter and angular diameter distance, respectively. The angular diameter distance and Hubble parameter can include different functions that explain dark energy behavior. These functions have two parameters w0 and w1 and one can constrain them with a chi-square technique.
General relativity and dark energy
In general relativity, the expansion of the universe is parametrized by a scale factor which is related to redshift:
The Hubble parameter, , in terms of the scale factor is:
where is the time-derivative of the scale factor. The Friedmann equations express the expansion of the universe in terms of Newton's gravitational constant, , the mean gauge pressure, , the Universe's density , the curvature, , and the cosmological constant, :
Observational evidence of the acceleration of the universe implies that (at present time) . Therefore, the following are possible explanations:
The universe is dominated by some field or particle that has negative pressure such that the equation of state:
There is a non-zero cosmological constant, .
The Friedmann equations are incorrect since they contain oversimplifications in order to make the general relativistic field equations easier to compute.
In order to differentiate between these scenarios, precise measurements of the Hubble parameter as a function of redshift are needed.
Measured observables of dark energy
The density parameter, , of various components, , of the universe can be expressed as ratios of the density of to the critical density, :
The Friedman equation can be rewritten in terms of the density parameter. For the current prevailing model of the universe, ΛCDM, this equation is as follows:
where m is matter, r is radiation, k is curvature, Λ is dark energy, and w is the equation of state. Measurements of the CMB from WMAP put tight constraints on many of these parameters; however it is important to confirm and further constrain them using an independent method with different systematics.
The BAO signal is a standard ruler such that the length of the sound horizon can be measured as a function of cosmic time. This measures two cosmological distances: the Hubble parameter, , and the angular diameter distance, , as a function of redshift . By measuring the subtended angle, , of the ruler of length , these parameters are determined as follows:
the redshift interval, , can be measured from the data and thus determining the Hubble parameter as a function of redshift:
Therefore, the BAO technique helps constrain cosmological parameters and provide further insight into the nature of dark energy.
See also
Baryon Oscillation Spectroscopic Survey
BINGO (telescope)
Euclid (spacecraft)
References
External links
Physical cosmology
Baryons | Baryon acoustic oscillations | Physics,Astronomy | 2,500 |
49,640,257 | https://en.wikipedia.org/wiki/Esholt%20Sewage%20Works%20Railway | Esholt Sewage Works Railway was a standard gauge works railway constructed in 1910 to serve a sewage works in Esholt, West Yorkshire, England.
The works were built to remove wool-grease and other wastes from effluent coming out of the many mills of the Bradford woollen district. At its peak, the railway extended to of track served by 11 locomotives, as well as a shorter section of narrow gauge railway served by three engines. Trains were employed to remove solid waste from the site; several of the engines were converted to run on oil derived from recovered wool-grease.
The railway was closed completely in 1977, but the sewage works continues to operate.
Origins
Bradford was a major force in woollen products in the 19th and into the 20th century; nearly 20% of the world's wool production was being handled at Bradford. A branch of the Leeds and Liverpool Canal extended up Bradford Dale from Shipley to a point near to where Bradford Forster Square railway station is today. Bradford Beck spilled into this canal arm and it suffered from very bad sewage problems. It was rumoured that the canal was so badly affected with incendiary chemicals and sulphureted hydrogen, that children used to set the canal alight.
Resolved to do something by new laws and the desire to rid themselves of the problem, Bradford Corporation initiated first the Frizinghall works (being the lowest part of the city at that time) and when this did not work, they bought the estate at Esholt adjacent to the River Aire. This was a protracted process that wasn't completed until 1906 with assent from parliament to build the works not being granted until 1909.
The railway
In 1910, a railway branch line was connected to the Midland Railway's Leeds & Bradford Railway Line, leaving as a northerly spur west of Apperley Viaduct and east of Thackley Tunnel. The spur left the mainline immediately east of the rail bridge over the Leeds & Liverpool Canal with the branch and associated sidings staying, for the most part, to the east and north of the canal, and west and south of the river as both curve north of Thackley. Branches at Thackley Hill bridged both watercourses. The connection with the Midland line required a signal box and exchange sidings for the transfer of wagons between the two systems.
Sludge was pressed into 'Cake' at the Press House, a long, by wide building which housed the railway wagons in the basement. This allowed the 'Cake' to be gravity fed into the railway wagons for transfer to another part of the site. This would involve running into a siding, dumping the 'Cake' and leaving it to dry, before being sold as fertiliser and transhipped via the exchange sidings on the Midland line.
At the peak of the workings in 1931, of track existed being worked over by 11 locomotives, some of which were converted to run on oil derived from wool grease. When the locomotives were not being used (especially at night) the grease was kept molten by piping steam into the fireboxes. The grade 'A' product of the sewage works was used by the railway companies as an axle grease for freight wagons. Coal for the sewage beds was transhipped into the works via the connection from the Midland Railway as was Sulphuric acid until the works commissioned their own Sulphur plant in 1922. Because the sewage was gravity fed into the works, some steep inclines were present (as steep as 1 in 49 in places) and several sidings were taken up and re-laid in line with the building programme and whenever a section became redundant.
A small section of gauge railway also ran around part of the site. This was operated by two Simplex petrol tractors and one small steam locomotive. Additionally, a short section of standard gauge track ran parallel to the Midland Line and ran underneath the line to access an area of land used for tipping.
By 1957, the works was down to of track and full employment for only two locomotives, 'Nellie' and 'Elisabeth', both Hudswell Clarke 0-4-0ST engines. Steam engines were the workhorses for most of the railway's life, only yielding to diesel traction in 1976. The railway closed in 1977 with the works engine shed being transported brick for brick to the Industrial Museum at Armley in Leeds.
As with other industrial railways, it was owned and operated by a private enterprise and not by a railway company. As such it was never grouped or nationalised. The railway was operated by the water division of Bradford Corporation until 1973, when Yorkshire Water was formed. Yorkshire Water eventually took over running the railway from Bradford Council in 1975.
The railway today
No railway exists at Esholt today, though many of the overbridges spanning the River Aire and the Leeds & Liverpool Canal are still extant. 0-4-0ST 'Nellie' was preserved at the Bradford Industrial Museum at Eccleshill, and one of the diesel engines, another 0-4-0 built by Hunslet of Leeds, found employment at Crossley's scrapyard just up the valley outside Shipley station on the Forster Square line.
References
External links
Aerial view of site from 1947
Esholt and surrounding area on a navigable 1947 map
Closed railway lines in Yorkshire and the Humber
Industrial railways in England
Sewerage infrastructure
Railway lines opened in 1910
Railway lines closed in 1977 | Esholt Sewage Works Railway | Chemistry | 1,097 |
51,088,515 | https://en.wikipedia.org/wiki/Libraries.io | Libraries.io is an open source web service that lists software development project dependencies and alerts developers to new versions of the software libraries they are using.
Libraries.io is written by Andrew Nesbitt, who has also used the code as the basis for DependencyCI, a service that tests project dependencies. A key feature is that the service checks for software license compliance.
As of 17 April 2022, the web service monitors 6,921,905 open source libraries and supports 32 different package managers. To gather the information on libraries, it uses the dominant package manager for each programming language that is supported. The website organizes them by programming language, package manager, license (such as GPL or MIT), and by keyword.
On November 14, 2017, Libraries.io announced its acquisition by Tidelift, an open-source software support company, with an intention to continue to develop and operate the service.
The code that runs the web service is available on GitHub and under the GNU Affero General Public License.
External links
Libraries.io source code
References
Free software websites
Software metrics
Code search engines
Internet properties established in 2015 | Libraries.io | Mathematics,Technology,Engineering | 235 |
34,298,214 | https://en.wikipedia.org/wiki/Dragontrail | Dragontrail is an alkali-aluminosilicate sheet glass manufactured by AGC Inc. It is engineered for a combination of thinness, lightness and damage-resistance, similarly to Corning's proprietary Gorilla Glass. The material's primary properties are its strength, allowing thin glass without fragility; its high scratch resistance; and its hardness with a Vickers hardness test rating of 595 to 673.
Cell phones and tablets
To date, some of the cell phone and tablet models that have incorporated Dragontrail protection are:
Alcatel 7 (By Metro PCS)
Alcatel Idol Alpha
Alcatel Hero 2
Alcatel One Touch Conquest
Alcatel One Touch Idol 3
Alcatel One Touch Idol 4 Pro
Alcatel Tetra
Alcatel TCL LX
Allview P8 Energy mini
Allview V2 Viper i
Allview V1 Viper i4G
Allview Viper E
Allview W1i
Allview W1s
Allview X2 Soul Lite
Allview X2 Soul Style
Allview X2 Soul Style + Platinum
BlackBerry DTEK 50/60
BlackBerry Motion
Bq Aquaris
Cherry Mobile 4/S4/S4 Plus/G1
Crosscall Trekker-S1
Doro 8080
Elephone P8000
eSTAR X45
Flipkart Billion Capture+
Galaxy Nexus
Getnord Onyx
Gionee Marathon M5 lite
Google Pixel 3a and 3a XL
Haier Esteem I70
Highscreen Power Rage Evo
i-mobile IQ 6
InnJoo One
InnJoo Two
Kruger&Matz DRIVE 3
Lava Iris 504q
Lava Pixel V1
Lava Pixel V2
Lava X8
Lava Agni 3 5G (2024)
Lenovo K3 Note (Also known as Lenovo A7000 Turbo in India, Model Number: K50a40)
Lenovo ThinkPad Yoga 12
LYF WATER 5
Meizu M2
Meizu M2 note
Oplus XonPhone 5
Oukitel K10
Philips Xenium I908
Polytron Prime 7
Samsung Galaxy J3 (2016)
Samsung Galaxy M10, M20, M30s
Samsung Galaxy On5, On7, On5 Pro, On7 Pro
Sony Ericsson Xperia Active
Sony Ericsson Xperia Acro S
Sony Xperia X Performance
Sony Xperia Z
Sony Xperia Z1
Sony Xperia Z2
Sony Xperia Z3
Sony Xperia Z5
Sony Xperia Z5 Premium
Stonex One
TrekStor WinPhone 4.7 HD
UMi Z
V341U
Videocon Krypton3 V50JG
WE T1
Wileyfox Spark/Spark+/SparkX
Xiaomi Redmi 1S/2/2 Prime
XOLO 8X-1000
XOLO BLACK 1X
XOLO Q1000
XOLO Q1010i
XOLO Win Q900s
ZTE Avid Plus
ZTE Obsidian
ZTE Sonata 2
References
External links
Patent
Dragontrail Glass comparison with Gorilla Glass
Materials science
Glass engineering and science
Glass applications
Glass trademarks and brands
Japanese brands | Dragontrail | Physics,Materials_science,Engineering | 615 |
53,927,859 | https://en.wikipedia.org/wiki/Aspergillus%20galapagensis | Aspergillus galapagensis (also named Neosartorya galapagensis) is a species of fungus in the genus Aspergillus. It is from the Fumigati section. Several fungi from this section produce heat-resistant ascospores, and the isolates from this section are frequently obtained from locations where natural fires have previously occurred. The species was first described in 2014. It has been isolated from soil in Ecuador. It has been reported to produce gregatins.
Growth and morphology
A. galapagensis has been cultivated on both Czapek yeast extract agar (CYA) plates and Malt Extract Agar Oxoid® (MEAOX) plates. The growth morphology of the colonies can be seen in the pictures below.
References
Further reading
galapagensis
Fungi described in 2014
Fungus species | Aspergillus galapagensis | Biology | 171 |
67,065,443 | https://en.wikipedia.org/wiki/Small%20packet | Small packet, also called packages, is a postal term that is internationally defined as mails less than 2 kg. Commonly, small items that are not flat enough to be sent as ordinary letter would be sent as small packets.
Gallery
References
Postal systems
Philatelic terminology | Small packet | Technology | 55 |
49,157,777 | https://en.wikipedia.org/wiki/Sarcodon%20quietus | Sarcodon quietus is a species of tooth fungus in the family Bankeraceae. Found in the Congo, it was described as new to science in 1967 by Dutch mycologist Rudolph Arnold Maas Geesteranus.
References
External links
Fungi described in 1967
Fungi of Africa
quietus
Fungus species | Sarcodon quietus | Biology | 60 |
12,775,176 | https://en.wikipedia.org/wiki/Parent%E2%80%93child%20interaction%20therapy | Parent–child interaction therapy (PCIT) is an intervention developed by Sheila Eyberg (1988) to treat children between ages 2 and 7 with disruptive behavior problems. PCIT is an evidence-based treatment (EBT) for young children with behavioral and emotional disorders that places emphasis on improving the quality of the parent-child relationship and changing parent-child interaction patterns.
Disruptive behavior is the most common reason for referral of young children for mental health services and can vary from relatively minor infractions such as talking back to significant acts of aggression. The most commonly treated Disruptive Behavior Disorders may be classified as Oppositional Defiant Disorder (ODD) or Conduct Disorder (CD), depending on the severity of the behavior and the nature of the presenting problems. The disorders often co-occur with Attention-Deficit Hyperactivity Disorder (ADHD). It uses a unique combination of behavioral therapy, play therapy, and parent training to teach more effective discipline techniques and improve the parent–child relationship.
PCIT is typically administered once a week, with 1-hour sessions, for 10-14 sessions total and consists of two treatment phases: Child-Directed Interaction (CDI) and Parent-Directed Interaction (PDI). The CDI component focuses on improving the quality of the parent-child relationship, which will help promote changes in behavior. This sets the foundation for the PDI stage, which continues to encourage appropriate play while also focusing on a structured and consistent approach to discipline.
History
PCIT was derived from several theories, including attachment theory, social learning theory, and parenting styles theory.
Attachment theory
According to attachment theory by Ainsworth, “sensitive and responsive parenting” during infancy and toddlerhood leads the child to develop an expectation that their needs can be met by the parent. Thus, parents who show their young children greater warmth and are more responsive and sensitive to their needs promote a sense of security that they can later apply to relationships with others. This can also help with more effective emotion regulation. Children who are referred to clinics for externalizing behaviors are more likely than non-referred children to display distress when separated from the parent and to display indicators of an insecure attachment to their parent.
The Child Directed Interaction (CDI) component of the PCIT applies attachment theory through its goal to “restructure the parent-child relationship and provide a secure attachment for the child”. The CDI component makes use of the idea that parents can have a dramatic effect on their child's behavior, especially during the early preschool years. This is a critical period where children are more responsive to their parent's and less so to other influences such as teachers or peers.
Social learning theory
Social learning theory suggests that new behaviors can be learned by watching and imitating the behaviors of others. Patterson (1975) further expands on this and proposes that child behavior problems are “inadvertently established or maintained by dysfunctional parent-child interactions”. There can be a “coercive interaction cycle” between parent and child where both try to control the behavior of the other. Behaviors such as arguing and aggression in children are reinforced by parent behaviors (e.g., withdrawal of demands), but negative parent behaviors can subsequently be reinforced by negative child behaviors. In sum, children can learn many behaviors from their parents’ feedback, but this can result in negative externalizing behaviors, as well. The PDI component targets this cycle specifically by establishing consistent parenting behaviors that encourage the desired behavior in children.
Parenting style theory
According to Diana Baumrind’s parenting style theory (year link citation) found that the authoritative parenting style leads to the healthiest outcomes for children transitioning into adolescence. This style combines responsive and nurturing interactions with clear communication and firm discipline. The influence of this theory can be seen particularly in the PDI treatment phase where parents are taught to use direct commands to increase desired behavior, along with other positive and nurturing behaviors.
Structure of the PCIT
Eyberg’s original paper (1988) thoroughly describes each assessment and treatment phase of the PCIT and includes suggestions for applying the therapy.
First, parents attend a training session during which the therapist explains each rule and its rationale. Each parent is also taught through one-on-one role play interactions with the therapist. Parents are also given a handout at the end of the session that summarizes the basic directions so they can review it at home.
After this training session, the sessions that follow will include the child. The sessions are held in a playroom, with the child playing with one parent at a time. Meanwhile, the therapist and the other parent will be observing the play through a one-way mirror or video system. The therapist can provide immediate feedback and suggestions through a “bug-in-ear” device or sit in the room to do the coaching. At the end of the session, the therapist discusses the child's progress, using summary sheets that parents can use to guide their interactions during practice sessions at home. These practice sessions serve as a “homework assignment” for parents, during which they practice the interaction with their child for five minutes a day, using homework sheets to track progress. The treatment begins with the Child-Directed Interaction phase, then is followed by the Parent-Directed Interaction (PDI) phase.
Child-Directed Interaction (CDI)
According to Eyberg (1988), the parent's goal during this stage is to follow the child's lead during play while being sure to follow the “Don’t Rules” and “Do Rules of CDI”. The child should be free to lead the activity and make their own decisions about what and how to play. By letting their children take control of the play, the parents help their child develop autonomy and independence.
Don’t rules of CDI
According to Eyberg (1988), the Don't rules help parents step back and encourage child-led play by avoiding commands, questions, and criticisms. Commands, or instructions, would take the lead away from the child could also introduce potential disagreements into the play. Parents are also encouraged to not ask questions. This can include questions such as “How about putting the toys away?” which are actually implied commands. The concern about asking questions is that they may come off as accusatory (“Why did you choose that toy?”) or take the conversation to an “adult” level instead of letting the child play freely and naturally. The general idea is that questions provide little information, so they have limited usefulness in therapy. The third “don’t” rule is to avoid criticizing. Though criticisms can range from mild to blatant attacks on the child, criticisms in general can lead to damaging effects on the child's self-esteem. As children learn which behaviors are good or bad, they rely on what their parents say about them and believe it. Criticisms may also frustrate or anger the child and can lead to a counterattack. Taken together, criticisms are not only unproductive in therapy, but also are threats to the positive relationship that the PCIT emphasizes.
Do rules of CDI
According to Eyberg (1988), the Do rules of CDI that promote positive behavior throughout play. The first Do is to describe what the child is doing during the activity. Doing this may seem unnatural at first, but describing serves a few purposes: it allows the child to (1) lead play, (2) improve attention towards independent activities, (3) clarify the activity and encourage the child to further elaborate the play, and (4) help teach the child different concepts in a positive way. For example, the child learns through positive feedback (“you found the red one”) instead of coercion (“find the red one”).
The second Do is imitation. Eyberg recommends that the parents “sit close and do the same thing as the child”. The parent can add to the child's play, or do something similar, but the focus should still remain on the child's style of play. The attention that imitation can demonstrate can show the child that the parent is interested and believes what they are doing is important. Imitation may even lead to the child imitating the parent. The aim is that through the parent-child play, the child can learn cooperative play skills that they can one day use with other children.
Parents are encouraged to reflect what the child says during play, the third Do of CDI. This helps parents practice listening to their child. For example, when the child says “The car is fast,” the parent might say “Yes, the car is fast”. These reflections show that the parent understands and accepts what the child is saying. Additionally, using reflective statements can improve the child's vocabulary and grammar by providing clarity to the child's thoughts. It also gives the child an opportunity to agree or disagree with the parent's understanding and elaborate if needed.
Praise is the fourth Do, and is very important because it can make children feel good and increase warmth, an important goal of the CDI. Praise statements such as “Good job!” show the child that their creations and actions are important. This is important because children tend to believe the things parents say to them, whether they be positive or negative. The manual specifies two types of praise. “Labeled praise” statements specify exactly what the parent likes about their behavior. For example, saying “You did a beautiful job of drawing that picture” not only teaches children that they did something the parent liked, but also teaches them what they did to earn that praise. Because PCIT can be used from ages 2 through 7, coaching takes into account the developmental differences at each age and teaches parents to be mindful of those differences. Parents are encouraged to praise and reflect all attempts of their child to verbally communicate, as speech skills are concurrently developing.
Parent-Directed Interaction (PDI)
According to Eyberg (1988), during the PDI component, parents continue the skills learned in the CDI, but this time they are taught new skills to lead the play. These skills include giving verbal directions and applying the appropriate consequences to the child in a fair manner that the child can understand clearly. These steps are practiced at the clinic, and parents are not encouraged to practice at home until they feel confident.
Eyberg (1988) states that he first step is to give clear, direct commands for the desired behavior from the child and to avoid indirect commands, which can be too vague and confusing to the child. For example, “Put this red table in the house” is a direct command. However, an indirect command such as “Will you color the leaves green?” can be interpreted by the child as a genuine question. Another example of an indirect command is “Let’s clean up the toys”, which does not indicate clearly if both the parent and child will be doing the task or how much of the task the child will do themselves. Additionally, phrases that are too general, such as “Be good”, should be avoided, as it does not provide enough information about what exactly is expected of the child. In sum, clear statements should be used towards the child so they can understand easily without getting confused.
Eyberg (1988) provides some guidelines for parents to teach parents when giving direct commands. First, the commands should be stated positively and should tell the child what to do, rather than what not to do. For example, “Put your hands in your lap” should be used instead of “Stop grabbing the toys”. Secondly, the command should be one that is age-appropriate for the child. For example, telling a 2-year-old “Tie your shoe” would be considered not age-appropriate. Lastly, the command should require only one behavior at a time. This way, children need not remember long strings of orders in a single command.
The second step of PDI involves labeled praise when the child displays the desired behavior. For example, “I like it when you do what I tell you to do so quickly!” tells the child what specific action pleased the parent and this praise will help increase that desired behavior.
The third step is to initiate time-out whenever the child is noncompliance. Eyberg states that noncompliance will be reinforced by both parental attention and when the child is able to get out of something they do not want to do. An example may be a warning followed by a three-minute time-out.
Eventually, as these skills are mastered by the parent, the commands can begin to address relevant behavioral problems the child may be displaying. The approach depends on the treatment goal. For example, if the goal is to increase a certain desired behavior, the parent must break the skill down into simpler parts that can be built on through practice and labeled praise until the child masters it.
Assessments
Dyadic Parent-Child Interaction System (DPICS)
DPICS is an observational system originally created for conduct problem families. It uses direct observations of behaviors to assess parent-child interactions. DPICS has undergone three revisions since its first edition published in 1981, and now includes a research and clinical version of the coding system. . The DPICS categories serve as indicators of relationship quality, measured by verbal and physical behaviors during social interactions. Examples of parent behavior categories are direct and indirect commands, behavior descriptions, reflections, labeled praise, unlabeled praise, questions, and negative talk. Child behavior categories include comply, noncomply, no opportunity to comply, physical positive and negative, yell, whine, smart talk, laugh, and destructive behavior. The clinical version of the manual reduces the number of parent and child codes to be more practical for clinicians to use (e.g., only compliance, noncompliance, and no opportunity to comply are used as child responses in the clinical manual)
Eyberg Child Behavior Inventory (ECBI)
The ECBI is a 36-item behavior scale that is used to track disruptive behaviors in children. It was constructed from data indicating the most typical problem behaviors reported by parents of conduct problem children. The measure includes two scales: Intensity and Problem. Parents report Intensity by rating how frequent each item occurs. The Problem scale asks parents “Is this behavioral problem for you?” to which parents respond “yes” or “no”. This measure can be used for children aged 2 to 16.
Applications
Behavior problems
Disruptive behavior problems are the leading reason for children's referrals to mental health professionals. and PCIT was first created to target these behaviors. Results from a randomized controlled trial examining the efficacy of PCIT on clinic referred children with diagnoses of Oppositional Defiant Disorder indicated that compared to the waitlist control group, parents interacted more positively with their children and were more successful at gaining compliance. Additionally, parents in the treatment group reported decreased parenting stress and more control. Parents also reported significant improvements in their child's behavior following treatment.
Similar results have been shown in a quasi-experimental study by Boggs and colleagues (2004) that evaluated families who completed the treatment program compared to families who dropped out of the study before completion. For those who completed treatment, parents reported positive changes 10–30 months following treatment in their child's behavior and their parenting stress. Those who dropped out of treatment early did not show significant changes.
In a meta-analysis that conducted a comprehensive review of PCIT's efficacy with children diagnosed with ADHD, ODD, or CD, PCIT was found to be an “efficacious intervention for improving externalizing behavior in children with disruptive behavior disorders”. Another meta-analysis that focused on parenting stress in addition to child behaviors as outcomes found PCIT to have a “beneficial impact on parents’ and primary caregivers’ perceptions of all outcomes examined, including child externalizing behaviors, child's temperament and self-regulatory abilities, frequency of behavior problems, the difficulty of parent-child interactions, and parent overall distress”.
The treatment effects of PCIT can also be demonstrated in school settings, despite the treatment program being lab- or home-based. In a study by Funderburk and colleagues (2009), school assessments were administered at 12 months and 18 months following PCIT. At 12 months, results indicated that children in the treatment group maintained their post-treatment improvements, improving within “normal range of conduct problems” compared to the control group. However, though maintaining improvements with compliance, the 18-month followup indicated some declines into the range of levels before treatment.
Child maltreatment
Studies have examined the effectiveness of PCIT with families at risk or engaged in child maltreatment. Evidence suggests that factors such as coercive patterns of parent-child interactions, less sensitivity towards the child, and insecure child attachment can be risks for child maltreatmen.t In a randomized controlled trial composing of 12-session PCIT, mothers reported less internalizing and externalizing behaviors in children in the PCIT group. Additionally, mothers reported less stress, more positive verbalizations and maternal sensitivity. Other studies have found similar results, including a reduction of abuse risk post-treatment compared to the waitlist control.
Foster care
PCIT may also be an effective intervention for maltreated children in foster care settings. Because children with behavioral problems in foster care are more likely to have multiple foster care placements and mental health problems, the interventions that improve foster parents’ skills in managing children's difficult behaviors are needed. Findings from a study comparing foster parents and their foster children to non-abusive biological parents and their children demonstrated PCIT's effectiveness in reducing child behavior problems and caregiver distress following treatment for both groups.
Depression
The PCIT has been adapted to treat major depressive disorder in preschool-aged children, called the PCIT-ED. The Emotional Development module (ED) was added to target emotion development impairments in very young children, specifically. Its goal is to help children regulate and understand their own emotions more effectively. The two phases of PCIT, CDI and PDI, are retained, but are shortened to six session per phase. Parents are taught skills that help their child in identifying and managing their emotions. For example, this may involve recognizing the child's “triggers” and using relaxation techniques to calm them. Often, parents may try to stop the child's expression of negative emotion, but during ED, parents are taught to tolerate these negative emotions so their child can learn to regulate them.
The pilot study of the PCIT-ED was an open trial study that examined a group of preschool children with depression, assessing symptoms before and after treatment. This study showed decreased depressive symptoms in children, and most children no longer met major depressive disorder criteria upon completion of treatment. Additionally, children improved their coping skills, prosocial behaviors, and thought processes. The first randomized controlled trial that compared PCIT-ED to psychoeducation in depressed preschoolers and their caregivers also showed significant improvement two weeks posttreatment for the PCIT-ED group in emotion development, child executive functioning, and parenting stress.
Separation anxiety disorder
Separation anxiety disorder (SAD) is the most common anxiety disorder in children which is characterized by an “excessive fear response to real or imagined separation from a caregiver”. PCIT involves many parenting skills that are important in reducing children's anxiety, such as command training, selective attention, reinforcement, and shaping the child's behavior.
Pilot study results by Pincus and colleagues (2008) evaluating the efficacy of PCIT in 10 young children with SAD showed that did not improve to nonclinical levels posttreatment, however there was improvement in the severity of SAD. Pincus and colleagues (2008) also proposed an adaptation to the PCIT that would include the Bravery-Directed Interaction (BDI) phase. The BDI phase includes a psychoeducational component for the parents about anxiety. It also includes a gradual exposure to the separation situations the child fears. This exposure is key for all anxiety disorders. The BDI focuses on establishing a sense of control in the child by giving them the freedom to choose one exposure activity a week from the “Bravery Ladder” homework assignment, rather than having their parent choose. An initial randomized controlled trial has been conducted to evaluate the modified PCIT, comparing its efficacy to a waitlist control group. It seeks to assess the maintenance of change at 3, 6, and 12 months posttreatment. Preliminary results of study show decreased severity of SAD post-treatment.
Domestic and interparental violence exposure
Children are at an especially high risk for externalizing and internalizing problems following interparental violence-exposure or domestic violence. Borrego and colleagues (2008) have provided rationale for the use of PCIT with domestic violence-exposed women and their children, proposing that the parent training component may be very beneficial for mothers who may have “low levels of confidence in their own parenting capabilities and may also have low self-esteem”. Additionally, Borrego and colleagues (2008) emphasized that because PCIT is relationship-based, it may improve the quality of the mother-child relationship, developing a secure attachment between mother and child, and may lead to a decrease in the severity of trauma symptoms experienced by both.
One study by Timmer and colleagues (2010) compared the effectiveness of PCIT in reducing behavior problems in maltreated children exposed to interparental violence (IPV) and similar children with no history of IPV-exposure. Results indicated that there were decreases in behavior problems and caregivers’ distress from pre- to posttreatment in both the IPV-exposed and non-exposed groups. However, there was no significant difference between variations of IPV exposure.
Delivery of treatment
In-home
The implementation of PCIT in the home has been examined in order to increase accessibility. Protocol was followed as closely as possible, with the exception that treatment was conducted within the home. Some modifications may be necessary in this setting. For example, the bug-in-ear (a small, wireless earpiece) was used for coaching parents could not be used. Instead, therapists were present in the same room for coaching, typically behind the caregiver, giving discrete feedback. Therapists were able to conduct DPICS observations, however these observations were coded live.
The in-home administration of PCIT in a single-subject study by Ware and colleagues (2012) has yielded promising results, such as decrease in caregiver use of negative behavior and increase in use of positive behavior and praise posttreatment. PCIT has also shown to improve child outcomes as well. PCIT completers were found to have significantly lower risk of child abuse compared to noncompleters, decrease in child behavior problems, and increased child compliance posttreatment.
There are certain advantages that come with in-home PCIT. For example, therapists are able to take advantage of more authentic, “real life” behaviors that may not be accurately captured within a laboratory or clinic setting. Additionally, in-home PCIT can combat attrition, a problem commonly faced by therapists.
This approach has potential drawbacks, as well. For example, because homes vary greatly across families, it is much more difficult for therapists control, unlike a laboratory or clinic setting. It may also be more difficult to keep children within the room and within the therapist's sight, as the child has more freedom to “escape” if needed. These problems can be avoided by deciding beforehand which room the therapy will take place and by minimizing potential distractions. Availability of resources can be an issue as well, particularly when the treatment requires use of age-appropriate toys that are typically controlled by the therapist in clinical settings. In homes, there may be limited options of activities. However, talking to the parent beforehand about what they might prefer to play with may be helpful, and the therapist can plan to bring the toys needed.
Community-based
PCIT implemented in the community involves administration in community settings such as in the home, mental health services agencies, or family services agencies. Few studies have examined the effectiveness of PCIT in community settings, however one implementation through community agencies has shown decreases in behavior problems, improved parent-child interactions, reduced parental stress in a four-family clinical case study posttreatment. Additionally, a study by Lanier and colleagues (2014) found PCIT to be effective for maltreatment prevention in a group of families receiving PCIT at posttreatment followup.
Internet-based
In an effort to increase accessibility and address obstacles of receiving treatment, especially in underserved communities, an internet-based delivery of PCIT has been proposed and tested. This method uses video conferencing, webcams, and wireless earpieces, allowing for therapists to continue to provide real-time feedback to caregivers, right from the comfort of their home. Advantages of this method include the ability to generalize findings better because families were treated in natural settings, which are the settings in which child disruptive behaviors are most likely to manifest.
Availability of resources can pose as a problem when implementing this method of PCIT. Success is dependent on families owning, or being provided, microphones, ear pieces, webcams, computers, and Wi-Fi hotspots. In homes that lack Wi-Fi or have suboptimal internet connections, real-time feedback from therapists may be affected. Treatment providers may be able to provide the necessary equipment for families to borrow, however this depends heavily on the availability of grant funds.
A randomized trial has been conducted with the Internet-Delivered Parent-Child Interaction Therapy (I-PCIT) and has shown support for its effectiveness in treating children with disruptive behavior disorders. Parents perceived less barriers to treatment when compared to those receiving clinic-based PCIT. This study demonstrated decreases in children's symptoms and burden to parents in a randomized clinical trial compared to a waitlist control group, and to traditional in-office PCIT administration. Additionally, roughly half of the children in the study no longer met the diagnostic criteria for disruptive behavior disorder.
Criticisms
In addition to the time-out component, Eyberg (1988) also recommended swatting child's bottom and other physical punishment as a form of discipline, however in a study by Timmer and colleagues (2005), physical punishment was not found to be necessary and has since been removed from the PCIT protocol. Timmer (2005) further suggested that it did not add anything and suggested a more hands-off approach to parenting.
Attrition rates among families receiving PCIT are an ongoing concern. In a meta-analysis by Thomas and Zimmer-Gembeck (2012), attrition rates ranged from 18 to 35% among studies that reported attrition.
See also
Behavior analysis of child development
References
External links
Official website
Behaviorism
Psychotherapy by type
Developmental psychology | Parent–child interaction therapy | Biology | 5,504 |
77,107,405 | https://en.wikipedia.org/wiki/PKS%201345%2B125 | PKS 1345+125 known as PKS 1345+12 and 4C +12.50, is an ultraluminous infrared galaxy (ULIG) with an active galactic nucleus, located in the constellation Boötes. With a redshift of 0.121740, the galaxy is located 1.7 billion light-years from Earth.
Characteristics
A merger of two gas-rich galaxies consisting of one elliptical and one spiral, PKS 1345+125 is the powerful radio galaxy ever detected in CO (1 → 0) to date with a radio luminosity of P408 MHz = 2.4 × 1026 W Hz−1. It presents a compact astrophysical jet that is 0.1" ~200 pc wide, a high molecular gas mass measuring 4.4 × 1010 M and contains a gigahertz peaked-spectrum radio source (GPS) within the extent of its narrow-line region (<~1 kpc). Through study of its radio structure, PKS 1345+125 shows a misaligned radio feature of ~49^deg^.
The galaxy is part of a family of "warm" (f25 m/f60 m 0.2, that is similar to the colors of Seyfert galaxies. Such infrared galaxies like PKS 1345+125, are in a transition state between the "cold" (f25 m/f60 m < 0.2) ULIG phenomenon, where active star formation are occurring, with their accretion disks forming around the black hole and in optical quasar phases. This shows molecular gas is used as a fuel source to power its active nucleus.
According to researchers who studied PKS 1345+125, the galaxy contains ratios of narrow optical emission lines; this indicates Seyfert 2 activity. The two nuclei in the galaxy have a projected separation of ≈ 2″ ~ 4 kpc and are surrounded by an extended asymmetrical galactic halo that is detected in both infrared and optical images. These signs shows both black holes are on a verge of merging. Furthermore, a powerful obscured quasar nucleus at wavelengths, is detected with a broad (△vFWHM ~ 2600 km s−1) Pa emission, through recent near-infrared spectroscopic observations.
In addition to narrow optical emission lines, the column densities of N(H I) = 2-7 x 10^18^T_s_ atoms cm^-2^ in PKS 134+125 is found to have line extent of almost 1000 km s^-1^, indicating large amounts of cold gas present, which is responsible for bending the radio jet. Compared to Arp 220, the infrared and interstellar gas properties are higher in PKS 1345+125.
Observation of PKS 1345+125
Researchers who studied PKS 1345+125 have suggested the radio source is a prime candidate for the link between young radio galaxies as well as ultraluminous infrared galaxies. From a VLBI study on neutral hydrogen inside nuclear regions of this object, they showed most gas detected close to the systemic velocity, are found to be associated with an off-nuclear cloud ( ~ 50 to 100 pc from its radio core. Not to mention, the gas has a column density of 1022 Tspin/100 k cm−2 with a H1 mass of 105 to 106 M○.
From the results, researchers hinted the interstellar cloud in PKS 1345+125 has presence of rich and clumpy interstellar medium located inside the centre. Such traces are left over from the merger event that triggered the activity in PKS 1345+125 and growth of the radio source, influenced the medium. The proximity of the gas cloud at the edge of the northern radio lobe according to them, is suggested to be interacting with the radio jet causing it to be bended. The velocity profile of the gas on the other hand, is relatively broad ( ~ 150 km s−1), which researchers interpret this as a sign of kinematical evidence for interaction of the radio plasma with the cloud.
Through imaging with Hubble Space Telescope and long-slit spectra by the William Herschel Telescope at La Plama in Spain, researchers detected young stellar populations in PKS 1345+125 with bright blue knots indicating super star clusters. These star clusters are found to have ages of tSSC < 6Myr with reddenings 0.2 < E(B - V) < 0.5 and solar masses of 106 < MYSPSSC < 107Msolar. The young stellar populations meanwhile, are in diffuse light that are stretched across the full extent of the halo with relatively young age of ~5 Myr. Researchers also studied the locations of super star clusters. The long-slit spectra shows they are moving at 450 km−1 in respect to local ambient gas; this is proven they either formed through fast moving gas streams infalling back to the galaxy's nuclear regions or by jet-induced star formation.
Radio source
The radio source in PKS 1345+125 is found to be a compact symmetric source according to researchers who observed it in optical and infra-red images. An extended line emission around ~20kpc, is said to be consistent with the asymmetric halo of diffuse emission. In its nucleus, 3 Gaussian components (narrow, intermediate and broad) are located. The broadest component (FWHM ~2000 km/s) is blue shifted by ~2000 km/s with respect to the galaxy halo and HI absorption, which they interpret it as material outflow.
Researchers further found evidence for high reddening and measure E(B-V)>0.92 for the broadest component in PKS 1345+125. From value of [S II]6716,6731, the electron densities of n_e<150 cm^{-3}, n_{e}>5300 cm^{-3} and n_{e}>4200 cm^{-3} are then estimated for all regions. According to them, total mass of line emitting gas is calculated as M_{gas}<10^6 solar masses. This proves PKS 1345+125 is a young radio source with nuclear regions covered by gas and dust cocoons.
Outflow of PKS 1345+125
The total kinetic outflow in PKS 1345+125 is 8 M_sun yr^-1, thanks to researchers who measured electron densities of Ne=2.94x10^3 cm^-3, Ne=1.47x10^4 cm^-3 and Ne=3.16x10^5 cm^-3 for the narrow, broad and very broad region components. But only a small fraction (0.13% of Lbol) of the accretion power available are driving the warm outflows. This is significantly less compared to accretion power required by majority of quasar feedback models (~5-10\% of Lbol). Although the model predicted the gas is removed through active galactic nucleus outflows from the host galaxy, the warm outflow is unable to do so. Possibly most of the outflow is either trapped by a dusty cocoon or in hotter or colder phrases. This result is not only important for studying young radio sources but for active galactic nuclei.
References
4C objects
Boötes
Luminous infrared galaxies
Seyfert galaxies
Radio galaxies
Interacting galaxies
048898
Quasars
Active galaxies
IRAS catalogue objects | PKS 1345+125 | Astronomy | 1,539 |
25,050,663 | https://en.wikipedia.org/wiki/Learning%20to%20rank | Learning to rank or machine-learned ranking (MLR) is the application of machine learning, typically supervised, semi-supervised or reinforcement learning, in the construction of ranking models for information retrieval systems. Training data may, for example, consist of lists of items with some partial order specified between items in each list. This order is typically induced by giving a numerical or ordinal score or a binary judgment (e.g. "relevant" or "not relevant") for each item. The goal of constructing the ranking model is to rank new, unseen lists in a similar way to rankings in the training data.
Applications
In information retrieval
Ranking is a central part of many information retrieval problems, such as document retrieval, collaborative filtering, sentiment analysis, and online advertising.
A possible architecture of a machine-learned search engine is shown in the accompanying figure.
Training data consists of queries and documents matching them together with the relevance degree of each match. It may be prepared manually by human assessors (or raters, as Google calls them), who check results for some queries and determine relevance of each result. It is not feasible to check the relevance of all documents, and so typically a technique called pooling is used — only the top few documents, retrieved by some existing ranking models are checked. This technique may introduce selection bias. Alternatively, training data may be derived automatically by analyzing clickthrough logs (i.e. search results which got clicks from users), query chains, or such search engines' features as Google's (since-replaced) SearchWiki. Clickthrough logs can be biased by the tendency of users to click on the top search results on the assumption that they are already well-ranked.
Training data is used by a learning algorithm to produce a ranking model which computes the relevance of documents for actual queries.
Typically, users expect a search query to complete in a short time (such as a few hundred milliseconds for web search), which makes it impossible to evaluate a complex ranking model on each document in the corpus, and so a two-phase scheme is used. First, a small number of potentially relevant documents are identified using simpler retrieval models which permit fast query evaluation, such as the vector space model, Boolean model, weighted AND, or BM25. This phase is called top- document retrieval and many heuristics were proposed in the literature to accelerate it, such as using a document's static quality score and tiered indexes. In the second phase, a more accurate but computationally expensive machine-learned model is used to re-rank these documents.
In other areas
Learning to rank algorithms have been applied in areas other than information retrieval:
In machine translation for ranking a set of hypothesized translations;
In computational biology for ranking candidate 3-D structures in protein structure prediction problems;
In recommender systems for identifying a ranked list of related news articles to recommend to a user after he or she has read a current news article.
Feature vectors
For the convenience of MLR algorithms, query-document pairs are usually represented by numerical vectors, which are called feature vectors. Such an approach is sometimes called bag of features and is analogous to the bag of words model and vector space model used in information retrieval for representation of documents.
Components of such vectors are called features, factors or ranking signals. They may be divided into three groups (features from document retrieval are shown as examples):
Query-independent or static features — those features, which depend only on the document, but not on the query. For example, PageRank or document's length. Such features can be precomputed in off-line mode during indexing. They may be used to compute document's static quality score (or static rank), which is often used to speed up search query evaluation.
Query-dependent or dynamic features — those features, which depend both on the contents of the document and the query, such as TF-IDF score or other non-machine-learned ranking functions.
Query-level features or query features, which depend only on the query. For example, the number of words in a query.
Some examples of features, which were used in the well-known LETOR dataset:
TF, TF-IDF, BM25, and language modeling scores of document's zones (title, body, anchors text, URL) for a given query;
Lengths and IDF sums of document's zones;
Document's PageRank, HITS ranks and their variants.
Selecting and designing good features is an important area in machine learning, which is called feature engineering.
Evaluation measures
There are several measures (metrics) which are commonly used to judge how well an algorithm is doing on training data and to compare the performance of different MLR algorithms. Often a learning-to-rank problem is reformulated as an optimization problem with respect to one of these metrics.
Examples of ranking quality measures:
Mean average precision (MAP);
DCG and NDCG;
Precision@n, NDCG@n, where "@n" denotes that the metrics are evaluated only on top n documents;
Mean reciprocal rank;
Kendall's tau;
Spearman's rho.
DCG and its normalized variant NDCG are usually preferred in academic research when multiple levels of relevance are used. Other metrics such as MAP, MRR and precision, are defined only for binary judgments.
Recently, there have been proposed several new evaluation metrics which claim to model user's satisfaction with search results better than the DCG metric:
Expected reciprocal rank (ERR);
Yandex's pfound.
Both of these metrics are based on the assumption that the user is more likely to stop looking at search results after examining a more relevant document, than after a less relevant document.
Approaches
Learning to Rank approaches are often categorized using one of three approaches: pointwise (where individual documents are ranked), pairwise (where pairs of documents are ranked into a relative order), and listwise (where an entire list of documents are ordered).
Tie-Yan Liu of Microsoft Research Asia has analyzed existing algorithms for learning to rank problems in his book Learning to Rank for Information Retrieval. He categorized them into three groups by their input spaces, output spaces, hypothesis spaces (the core function of the model) and loss functions: the pointwise, pairwise, and listwise approach. In practice, listwise approaches often outperform pairwise approaches and pointwise approaches. This statement was further supported by a large scale experiment on the performance of different learning-to-rank methods on a large collection of benchmark data sets.
In this section, without further notice, denotes an object to be evaluated, for example, a document or an image, denotes a single-value hypothesis, denotes a bi-variate or multi-variate function and denotes the loss function.
Pointwise approach
In this case, it is assumed that each query-document pair in the training data has a numerical or ordinal score. Then the learning-to-rank problem can be approximated by a regression problem — given a single query-document pair, predict its score. Formally speaking, the pointwise approach aims at learning a function predicting the real-value or ordinal score of a document using the loss function .
A number of existing supervised machine learning algorithms can be readily used for this purpose. Ordinal regression and classification algorithms can also be used in pointwise approach when they are used to predict the score of a single query-document pair, and it takes a small, finite number of values.
Pairwise approach
In this case, the learning-to-rank problem is approximated by a classification problem — learning a binary classifier that can tell which document is better in a given pair of documents. The classifier shall take two documents as its input and the goal is to minimize a loss function . The loss function typically reflects the number and magnitude of inversions in the induced ranking.
In many cases, the binary classifier is implemented with a scoring function . As an example, RankNet adapts a probability model and defines as the estimated probability of the document has higher quality than :
where is a cumulative distribution function, for example, the standard logistic CDF, i.e.
Listwise approach
These algorithms try to directly optimize the value of one of the above evaluation measures, averaged over all queries in the training data. This is often difficult in practice because most evaluation measures are not continuous functions with respect to ranking model's parameters, and so continuous approximations or bounds on evaluation measures have to be used. For example the SoftRank algorithm. LambdaMART is a pairwise algorithm which has been empirically shown to approximate listwise objective functions.
List of methods
A partial list of published learning-to-rank algorithms is shown below with years of first publication of each method:
{|class="wikitable sortable"
! Year || Name || Type || Notes
|-
| 1989 || OPRF || 2pointwise || Polynomial regression (instead of machine learning, this work refers to pattern recognition, but the idea is the same).
|-
| 1992 || SLR || 2pointwise || Staged logistic regression.
|-
| 1994 || NMOpt || 2listwise || Non-Metric Optimization.
|-
| 1999 || MART (Multiple Additive Regression Trees)|| 2pairwise ||
|-
| 2000 || Ranking SVM (RankSVM) || 2pairwise || A more recent exposition is in, which describes an application to ranking using clickthrough logs.
|-
| 2001 || Pranking|| 1pointwise || Ordinal regression.
|-
| 2003 || RankBoost || 2pairwise ||
|-
| 2005 || RankNet || 2pairwise ||
|-
| 2006 || IR-SVM|| 2pairwise || Ranking SVM with query-level normalization in the loss function.
|-
| 2006 || LambdaRank|| pairwise/listwise || RankNet in which pairwise loss function is multiplied by the change in the IR metric caused by a swap.
|-
| 2007 || AdaRank|| 3listwise ||
|-
| 2007 || FRank || 2pairwise || Based on RankNet, uses a different loss function - fidelity loss.
|-
| 2007 || GBRank || 2pairwise ||
|-
| 2007 || ListNet || 3listwise ||
|-
| 2007 || McRank || 1pointwise ||
|-
| 2007 || QBRank || 2pairwise ||
|-
| 2007 || RankCosine|| 3listwise ||
|-
| 2007 || RankGP|| 3listwise ||
|-
| 2007 || RankRLS || 2pairwise ||
Regularized least-squares based ranking. The work is extended in
to learning to rank from general preference graphs.
|-
| 2007 || SVMmap || 3listwise ||
|-
| 2008 || LambdaSMART/LambdaMART|| pairwise/listwise || Winning entry in the Yahoo Learning to Rank competition in 2010, using an ensemble of LambdaMART models. Based on MART (1999) “LambdaSMART”, for Lambda-submodel-MART, or LambdaMART for the case with no submodel.
|-
| 2008 || ListMLE|| 3listwise || Based on ListNet.
|-
| 2008 || PermuRank|| 3listwise ||
|-
| 2008 || SoftRank|| 3listwise ||
|-
| 2008 || Ranking Refinement || 2pairwise || A semi-supervised approach to learning to rank that uses Boosting.
|-
| 2008 || SSRankBoost || 2pairwise|| An extension of RankBoost to learn with partially labeled data (semi-supervised learning to rank).
|-
| 2008 || SortNet || 2pairwise|| SortNet, an adaptive ranking algorithm which orders objects using a neural network as a comparator.
|-
| 2009 || MPBoost|| 2pairwise || Magnitude-preserving variant of RankBoost. The idea is that the more unequal are labels of a pair of documents, the harder should the algorithm try to rank them.
|-
| 2009 || BoltzRank || 3listwise || Unlike earlier methods, BoltzRank produces a ranking model that looks during query time not just at a single document, but also at pairs of documents.
|-
| 2009 || BayesRank || 3listwise || A method combines Plackett-Luce Model and neural network to minimize the expected Bayes risk, related to NDCG, from the decision-making aspect.
|-
| 2010 || NDCG Boost || 3listwise || A boosting approach to optimize NDCG.
|-
| 2010 || GBlend || 2pairwise || Extends GBRank to the learning-to-blend problem of jointly solving multiple learning-to-rank problems with some shared features.
|-
| 2010 || IntervalRank || 2pairwise & listwise ||
|-
| 2010 || CRR|| 2pointwise & pairwise || Combined Regression and Ranking. Uses stochastic gradient descent to optimize a linear combination of a pointwise quadratic loss and a pairwise hinge loss from Ranking SVM.
|-
| 2014 || LCR|| 2pairwise || Applied local low-rank assumption on collaborative ranking. Received best student paper award at WWW'14.
|-
|2015
|FaceNet
|pairwise
|Ranks face images with the triplet metric via deep convolutional network.
|-
|2016
|XGBoost
|pairwise
|Supports various ranking objectives and evaluation metrics.
|-
|2017 || ES-Rank|| listwise || Evolutionary Strategy Learning to Rank technique with 7 fitness evaluation metrics.
|-
| 2018 || DLCM || 2listwise || A multi-variate ranking function that encodes multiple items from an initial ranked list (local context) with a recurrent neural network and create result ranking accordingly.
|-
|2018
|PolyRank
|pairwise
|Learns simultaneously the ranking and the underlying generative model from pairwise comparisons.
|-
|2018 || FATE-Net/FETA-Net|| listwise || End-to-end trainable architectures, which explicitly take all items into account to model context effects.
|-
|2019
|FastAP
|listwise
|Optimizes Average Precision to learn deep embeddings.
|-
|2019
|Mulberry || listwise & hybrid || Learns ranking policies maximizing multiple metrics across the entire dataset.
|-
|2019
|DirectRanker || pairwise || Generalisation of the RankNet architecture.
|-
| 2019 || GSF || 2listwise || A permutation-invariant multi-variate ranking function that encodes and ranks items with groupwise scoring functions built with deep neural networks.
|-
|2020
|RaMBO
|listwise
|Optimizes rank-based metrics using blackbox backpropagation.
|-
|2020
|PRM|| pairwise || Transformer network encoding both the dependencies among items and the interactions between the user and items.
|-
| 2020 || SetRank || 2listwise || A permutation-invariant multi-variate ranking function that encodes and ranks items with self-attention networks.
|-
|2021
|PiRank|| listwise || Differentiable surrogates for ranking able to exactly recover the desired metrics and scales favourably to large list sizes, significantly improving internet-scale benchmarks.
|-
|2022
|SAS-Rank
|listwise
|Combining Simulated Annealing with Evolutionary Strategy for implicit and explicit learning to rank from relevance labels.
|-
|2022
|VNS-Rank
|listwise
|Variable Neighborhood Search in 2 Novel Methodologies in AI for Learning to Rank.
|-
|2022
|VNA-Rank
|listwise
|Combining Simulated Annealing with Variable Neighbourhood Search for Learning to Rank.
|-
|2023
|GVN-Rank
|listwise
|Combining Gradient Ascent with Variable Neighbourhood Search for Learning to Rank.
|}
Note: as most supervised learning-to-rank algorithms can be applied to pointwise, pairwise and listwise case, only those methods which are specifically designed with ranking in mind are shown above.
History
Norbert Fuhr introduced the general idea of MLR in 1992, describing learning approaches in information retrieval as a generalization of parameter estimation; a specific variant of this approach (using polynomial regression) had been published by him three years earlier. Bill Cooper proposed logistic regression for the same purpose in 1992 and used it with his Berkeley research group to train a successful ranking function for TREC. Manning et al. suggest that these early works achieved limited results in their time due to little available training data and poor machine learning techniques.
Several conferences, such as NeurIPS, SIGIR and ICML have had workshops devoted to the learning-to-rank problem since the mid-2000s (decade).
Practical usage by search engines
Commercial web search engines began using machine-learned ranking systems since the 2000s (decade). One of the first search engines to start using it was AltaVista (later its technology was acquired by Overture, and then Yahoo), which launched a gradient boosting-trained ranking function in April 2003.
Bing's search is said to be powered by RankNet algorithm, which was invented at Microsoft Research in 2005.
In November 2009 a Russian search engine Yandex announced that it had significantly increased its search quality due to deployment of a new proprietary MatrixNet algorithm, a variant of gradient boosting method which uses oblivious decision trees. Recently they have also sponsored a machine-learned ranking competition "Internet Mathematics 2009" based on their own search engine's production data. Yahoo has announced a similar competition in 2010.
As of 2008, Google's Peter Norvig denied that their search engine exclusively relies on machine-learned ranking. Cuil's CEO, Tom Costello, suggests that they prefer hand-built models because they can outperform machine-learned models when measured against metrics like click-through rate or time on landing page, which is because machine-learned models "learn what people say they like, not what people actually like".
In January 2017, the technology was included in the open source search engine Apache Solr. It is also available in the open source OpenSearch and the source-available Elasticsearch. These implementations make learning to rank widely accessible for enterprise search.
Vulnerabilities
Similar to recognition applications in computer vision, recent neural network based ranking algorithms are also found to be susceptible to covert adversarial attacks, both on the candidates and the queries. With small perturbations imperceptible to human beings, ranking order could be arbitrarily altered. In addition, model-agnostic transferable adversarial examples are found to be possible, which enables black-box adversarial attacks on deep ranking systems without requiring access to their underlying implementations.
Conversely, the robustness of such ranking systems can be improved via adversarial defenses such as the Madry defense.
See also
Content-based image retrieval
Multimedia information retrieval
Image retrieval
Triplet loss
References
External links
Competitions and public datasets
LETOR: A Benchmark Collection for Research on Learning to Rank for Information Retrieval
Yandex's Internet Mathematics 2009
Yahoo! Learning to Rank Challenge
Microsoft Learning to Rank Datasets
Information retrieval techniques
Machine learning
Ranking functions | Learning to rank | Engineering | 4,122 |
23,057,932 | https://en.wikipedia.org/wiki/Forsythia%20%C3%97%20intermedia | Forsythia × intermedia, or border forsythia, is an ornamental deciduous shrub of garden origin.
Description
The shrub has an upright habit with arching branches and grows to 3 to 4 metres high. The opposite leaves turn yellowish or occasionally purplish in the autumn before falling. The bright yellow flowers are produced on one- to two-year-old growth and may be solitary or in racemes from 2 to 6.
Origin
The hybrid is thought to be a cross between Forsythia viridissima and F. suspensa var. fortunei. A plant of seedling origin was discovered growing in the Göttingen Botanical Garden in Germany by the director of the Royal Prussian Academy of Forestry in Münden, H. Zabel in 1878. Zabel formally described and named the hybrid in Gartenflora in 1885. It was introduced to the Arnold Arboretum in the United States in 1889.
Cultivation
The hybrid is best suited to a position in full sun or partial shade and is drought-tolerant. Like some other forsythias it is one of the earliest shrubs to flower. Well adapted to temperature changes, it blooms with bright yellow flowers that are noticeable even in twilight. It is one of several forsythia species that are widely cultivated in gardens and parks.
Cultivars
Cultivars include (those marked have gained the Royal Horticultural Society's Award of Garden Merit):
'Arnold Dwarf' – low-growing with pale yellow flowers
'Beatrix Farrand' – a particularly floriferous cultivar
'Gold Tide' ('Courtasol') – floriferous, with deep yellow autumn colour
'Karl Sax' – deep yellow flowers with orange lines in the throat. Introduced by the Arnold Arboretum in 1960.
'Lynwood' – large flowers with broad petals
'Lynwood Variety'
'Spectabilis'
'Spring Glory' – purple-tinged foliage in autumn
'Variegata' – leaves with contrasting cream edges
='Courtalyn'
Chemistry
The first dirigent protein was discovered in Forsythia intermedia. This protein has been found to direct the stereoselective biosynthesis of (+)-pinoresinol from coniferyl alcohol monomers.
References
External links
Forsythieae
Hybrid plants | Forsythia × intermedia | Biology | 456 |
9,988,015 | https://en.wikipedia.org/wiki/Tilda%20Johnson | Tilda Johnson, introduced as the Queen of the Werewolves and also known as Dr. Nightshade, Deadly Nightshade, or simply Nightshade, is a fictional character appearing in American comic books published by Marvel Comics. Introduced as a supervillain opposing Captain America, Falcon, Power Man, Iron Fist, and Black Panther, she is later reformed, becoming the superhero Nighthawk and joining the Avengers in 2017.
Gabrielle Dennis portrayed Tilda Johnson in the second season of the Marvel Cinematic Universe (MCU) / Netflix series Luke Cage. Additionally, Nabiyah Be was intended to portray Johnson in the MCU film Black Panther, but was renamed Linda Johnson due to Dennis being announced to portray Johnson in Luke Cage.
Publication history
Tilda Johnson first appeared in Captain America and the Falcon #164 (August 1973), created by Steve Englehart and Alan Lee Weiss.
Fictional character biography
Queen of the Werewolves
Tilda Johnson was born to a poor family in New York City. As a child, she possessed a natural aptitude in science. When she was a teenager, she began to use this extensive knowledge in pursuing a career as a criminal scientist. She received assistance from the Yellow Claw in developing a way to change normal humans so that they became compliant creatures similar to werewolves, and attempted to transform convicts into a werewolf army, but Captain America and S.H.I.E.L.D. stopped their plan. She later took control of a S.H.I.E.L.D. facility, and used pheromones to force Captain America to battle the Falcon, but was defeated. She clashes with Power Man and Iron Fist on several occasions.
Superia later made Nightshade her second-in-command over the Femizons. She helps develop a serum to transform men into women which she uses on Captain America and Paladin. She also helped Superia develop her sterilization bomb. She was also involved in a scheme with Dredmund Druid, though as a double agent for Superia. She used a serum to transform Captain America and the ordinary people of Starkesboro, Massachusetts into pseudo-werewolves.
MODOK's 11
Nightshade joined MODOK's 11, with the main objective of stealing the powerful Hypernova. It has been revealed after her last battle against the Black Panther, she tried to start her life over without crime. However, as she was self-taught and had no official degrees, the only medical job she could get was as a receptionist at a hospital. After she pointed out a mistake by one of the doctors, she was fired immediately and contemplated suicide, until MODOK contacted her and hired her for the heist. She had "used up all [her] second chances" and could not afford to turn MODOK down. She developed a friendship with her teammates Armadillo and Puma, and showed this strongly when backing up Puma in saving the Living Laser's life (and secretly giving him his Puma powers back through her "werewolf serum"). The three of them were the only villains to remain loyal to MODOK and get their cash (with a bonus); they appear to be sticking together, and she has offered to help Puma with his legal defense.
Shadowland
During the Shadowland storyline, Nightshade organized Flashmob, a group of former Luke Cage enemies, in order to take on the new Power Man, Victor Alvarez. Although Flashmob was defeated and incarcerated at Ryker's Island, Nightshade's lawyer Big Ben Donovan mentions that he has plans to have them released from Ryker's Island. Donovan was able to secure the release of some of the members, but others had to remain incarcerated due to the warrants and/or parole violations. During the Spider-Island storyline, Nightshade is among the villains that have been infected by the bedbugs that bestowed spider powers on her. She alongside Cottonmouth and Flashmob ended up fighting Heroes for Hire.
Reformation
A reformed Nightshade later allies with the Nighthawk of Earth-31916, helping him defend Chicago from a group of white nationalists called the True Patriots, and the Revelator. Sometime later, they help Hawkeye and Red Wolf after they find barrels of epidurium, a synthetic skin used to build Life-Model Decoys, on a truck that was hijacked. They go to an abandoned coal factory where they end up being attacked by armed soldiers led by Nick Fury. It's later revealed, that Nick Fury, as well as Dum Dum Dugan, Gabe Jones and the other agents, are Life-Model Decoys due to their outdated knowledge and technology. They later thwart an attack by gunmen attempting to rob the base. After defeating the gunmen, Nightshade decides to join Hawkeye and Red Wolf, saying her goodbyes to Nighthawk.
Sometime later, the group stops at Dungston, Iowa when their van breaks down. Hawkeye calls Wheels Wolinski to help fix the van until it is revealed that some of the residents are Skrulls, who are being hunted down by mysterious men. While Hawkeye, Red Wolf and Nightshade are fighting, Wolinski discovers that the van has an A.I. system, who convinces him to help in the fight. It is later revealed that the attackers are also Skrulls, led by Super-Skrull. Wolinski then manages to turn the van into a big robot and defeats Super-Skrull. Hawkeye then negotiates with Nick Fury Jr. to provide protection for the town's residents.
Becoming Nighthawk
During the Secret Empire storyline, while Hawkeye joins the Underground resistance following Hydra's takeover in the United States, the rest of the team gather their own resistance army to help the people in rural areas that are being affected by Hydra's cruel treatment. Tilda also reveals that she became the new Nighthawk, after the former was killed by Hydra soldiers. After several successful victories, the resistance heads to a secret base in South Dakota and prepares for their next attack until Hydra forces raid the base. During the battle, Red Wolf and Tilda have a private conversation, in which both confess their feelings for each other, and they share a kiss. They then head out to help the resistance defeat Hydra.
Powers and abilities
Tilda Johnson is an extraordinary genius, and extensively self-taught in genetics, biochemistry, cybernetics, robotics and physics. She also obtained a doctoral degree from an undisclosed university while in prison.
Nightshade sometimes wears protective battle armor, including silver spikes for protection from attack by werewolves. She has created an array of advanced weaponry, and has built numbers of humanoid robots. She created a chemical serum to transform normal humans into werewolves under her control and has used concentrated pheromones to control men through her allure.
Nightshade apparently secretes chemical pheromones from her body that affect the will of certain animals, including werewolves, making them obedient to her commands.
Other characters named Nightshade
Netherworld Nightshade
The man also known as Nightshade is from the Netherworld and the twin brother of Wolfsbane. He wielded Excalibre but his sword was shattered by the Black Knight. He could transform into a giant raven and used the enchanted sword Nightbringer.
Nightshade 2099
In the alternate future set in 2099 A.D., Nightshade 2099 is a research organization rivaling Alchemax. Members included Angela Daskalakis, Miss Pivot, and Travesty. All its members were killed.
Logan Lewis
Logan Lewis is younger Tilda Johnson's cousin, who followed her legacy by adopting Nightshade codename for heroism.
In other media
Two characters inspired by Tilda Johnson appear in media set in the Marvel Cinematic Universe (MCU).
Tilda Johnson herself appears in the second season of the MCU Netflix series Luke Cage, portrayed by Gabrielle Dennis. This version, also known by her birth name of "Matilda Maybelline Dillard", is the estranged daughter of Mariah Dillard, who was raped by her uncle "Pistol Pete" Stokes and denied an abortion by her mother "Mama" Mabel Stokes. While growing up in the care of Mariah's cousins, the Johnsons, Tilda initially believed her father was Mariah's late husband Dr. Jackson Dillard, became close to her cousin Cottonmouth, and became a holistic doctor. In the present, Tilda reluctantly reconnects with Mariah due to the latter's efforts to improve her publicity, becomes involved with Bushmaster after one of his men forces her to help him, and learns the truth about her father, Mariah's crimes, and Cottonmouth's death. After Mariah massacres several innocents to lure out Bushmaster, Tilda disowns and later fatally poisons her, believing she will receive everything in her mother's will. However, she only receives Cottonmouth's keyboard as Mariah left his club, Harlem's Paradise, to Luke Cage.
In June 2017, Nabiyah Be confirmed that she had been cast as Tilda Johnson in the MCU film Black Panther (2018), with plans for her to reprise the role in future films. After Dennis was announced to have been cast as Johnson in Luke Cage in July 2017, Be's character was renamed Linda Johnson in reshoots. Throughout the film, she assists her boyfriend Killmonger in his plans until he kills her to reach Ulysses Klaue.
See also
Nighthawk (Marvel Comics)
References
African-American superheroes
Characters created by Steve Englehart
Comics characters introduced in 1973
Fictional biochemists
Fictional characters from New York City
Fictional roboticists
Marvel Comics female superheroes
Marvel Comics female supervillains
Marvel Comics scientists | Tilda Johnson | Chemistry | 2,015 |
7,405,199 | https://en.wikipedia.org/wiki/Adnoun | Adnoun is a linguistic term used with two different meanings.
Hyponym of adjective
An adnoun is a kind of lexical category. In English, it is a word that is usually an adjective, but is being used as a noun. The origin of the word is thought to date to around 1763-1792. Often these usages are simply identified as the noun form of the word.
Examples:
"guide-dogs for the blind", "blind" is an adnoun because it stands in for the noun phrase "blind people"
"tax cuts for the rich", "rich" is an adnoun because it stands in for the noun phrase "rich people"
Synonym of adjective
Adnoun is an alternative term, which is considered to be archaic, for adjective. As John Eliot states in his 1666 Indian Grammar Begun..., "An Adnoun is a part of Speech that attendeth upon a Noun, and signifieth the Qualification thereof."
References
Syntactic entities
Parts of speech | Adnoun | Technology | 213 |
52,480,271 | https://en.wikipedia.org/wiki/OpenLB | OpenLB is an object-oriented implementation of the lattice Boltzmann methods (LBM). It is the first implementation of a generic platform for LBM programming, which is shared with the open source community (GPLv2).
The code is written in C++ and is used by application programmers as well as developers, with the ability to implement custom models
OpenLB supports complex data structures that allow simulations in complex geometries and parallel execution using MPI, OpenMP and CUDA on high-performance computers.
The source code uses the concepts of interfaces and templates, so that efficient, direct and intuitive implementations of the LBM become possible.
The efficiency and scalability has been checked and proved by code reviews.
A user manual and a source code documentation by DoxyGen are available on the project page.
Functions
OpenLB is being constantly developed. By now the following features are implemented:
Computational fluid dynamics in complex geometry
Automatic generation of a grid
Turbulent flow
Multi-component flow
Thermal flow
Light radiation
Topology optimizing
Particle flow (Euler–Euler and Euler–Lagrange method)
Automated grid generation
Automated grid generation is one of the great advantages of OpenLB over other CFD software packages. The main advantages are listed below:
Use of geometries in the STL file format or geometrically primitive forms (e.g. ball, cylinder, cone) and their union, intersection and difference
Very fast voxelization: 6003 ~ 1 minute
Handling non-watertight surfaces
Memory-friendly using octrees
Load distribution for parallel execution with MPI, OpenMP and CUDA.
The automatic grid generation can assume both an STL file as well as primitive geometries. For the geometry, a uniform and rectangular grid is created which encloses the entire space of the geometry. The superfluous grid cells are then removed and the remaining cuboids are shrunk to fit the given geometry. Finally, the grid is distributed to different threads or processors for the parallel execution of the simulation. The boundary conditions and start values can be set using material numbers.
Literature
Krause, Mathias J. and Latt, Jonas and Heuveline, Vincent. "Towards a hybrid parallelization of lattice Boltzmann methods." Computers & Mathematics with Applications 58.5 (2009): 1071–1080.
Heuveline, Vincent, and Mathias J. Krause. "OpenLB: towards an efficient parallel open source library for lattice Boltzmann fluid flow simulations." International Workshop on State-of-the-Art in Scientific and Parallel Computing. PARA. Vol. 9. 2010.
Krause, Mathias J., Thomas Gengenbach, and Vincent Heuveline. "Hybrid parallel simulations of fluid flows in complex geometries: Application to the human lungs." European Conference on Parallel Processing. Springer Berlin Heidelberg, 2010.
Krause, Mathias J. "Fluid flow simulation and optimisation with lattice Boltzmann methods on high performance computers: application to the human respiratory system." Karlsruhe Institute of Technology, KIT (2010).
Trunk, Robin, et al. "Inertial dilute particulate fluid flow simulations with an Euler–Euler lattice Boltzmann method." Journal of Computational Science (2016).
Mink, Albert, et al. "A 3D Lattice Boltzmann method for light simulation in participating media." Journal of Computational Science (2016).
Awards
Winner Mimics Innovation Award (2011)
Honorary certificate in the Group Humanitarian Impact, "Itanium® Solutions Alliance Innovation Awards" (2009)
Finalist in the Group Humanitarian Impact Innovation, "Itanium® Solutions Alliance Innovation Awards" (2007)
References
External links
Official website
Dynamic Cross Flow Filtration with OpenLB (YouTube Video)
OpenLB Trailer (YouTube Video)
C++ software
Computational fluid dynamics
Computer-aided engineering software for Linux
Continuum mechanics
Free science software
Free software programmed in C++
Open Source computer aided engineering applications
Scientific simulation software | OpenLB | Physics,Chemistry | 815 |
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