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47,315,930 | https://en.wikipedia.org/wiki/Fairphone%202 | The Fairphone 2 is a touchscreen-based, dual-SIM smartphone designed to be easily repaired by the user. First released in October 2015, it was the first modular smartphone available for purchase and has since received both hardware improvements and major software updates, initially shipping with Android 5 "Lollipop" and running Android 10 as of November 2022. Production ceased in 2018.
It was the second phone from the social enterprise Fairphone and the first one completely designed by them. The phone was ethically sourced, using conflict-free minerals, Fair trade gold and recycled materials. It was assembled in audited factories with good working conditions.
Design
Hardware choices
The phone was designed to have a higher life expectancy (five years) than other phones.
An important challenge with the Fairphone 1 was a system on a chip (SoC) Mediatek MT6589 that was not widely used and thus did not receive long-term software support from its manufacturer. For the Fairphone 2, Fairphone chose the widely used Snapdragon 801 platform (a high-end, early 2014 platform); hoping to maintain longer term support.
Fairphone deliberately did not include recent innovations like wireless charging or USB-C ports, intending for this to lead to lower prices and maintenance. However, the phone's modular design allows the modules to be changedwith updated components. Newer versions of the modular design contain cameras.
The back of the Fairphone 2 was equipped with a USB pin-out and charging input, allowing aftermarket back covers with extended capabilities.
Ethical considerations
The phone was designed to have a lower environmental impact than comparable mass-market smartphones, with an expected lifespan of five years. The modular design allows components to be replaced individually.
Many electronic devices contain conflict minerals (tin, tungsten, tantalum and gold) from the Democratic Republic of the Congo (DRC), used by armies and rebel groups to fund war in the country. Therefore, some manufacturers avoid all materials from the DRC, which reduces employment opportunities in the country. The Fairphone 2 supply chain was audited to ensure that these materials come from mines that do not fund armed groups while supporting local communities in the DRC (where possible) to provide an alternative to conflict mines. The tantalum and tin ores are sourced from conflict-free mines in the DRC, the tungsten was from Rwanda, and the gold was from a Fairtrade certified mine in Peru. In addition, the phone includes recycled plastic, copper, and tungsten.
Hi-P assembled the Fairphone 2 in Suzhou, China, in a factory that has been audited to ensure that it meets high standards for working conditions and for the environment.
Modular design
The Fairphone 2 was the first modular smartphone available to the general public. The modular, repairable design was designed to increase longevity, with an additional focus on increasing the product's recyclability. The phone components are designed to be replaceable, with the end user only needing to use a screwdriver to replace components of the phone. In addition, it was possible to replace individual components within each module.
The phone received a 10 out of 10 score for smartphone repairability from iFixit, the highest score ever given to a phone.
The phone consists of seven removable parts: the main chassis, the battery, the display assembly, the rear camera module, the top module (selfie camera, headphones, speaker, sensors), the bottom module (loudspeaker, vibration, microphone and charging port), and the back protective cover. Except for an updated slim case design, the first module set to be upgraded the cameras, with a new rear camera module (with a dual LED flash and 12-megapixel camera) and top module (with a 5-megapixel camera) in September 2017.
Software
Costs
The phone was primarily funded through pre-orders and was mostly sold directly, though in some markets the phone was available through resellers such as The Phone Co-op in the UK. The pre-order campaign started on 16 July 2015 and ended on 30 September 2015, with 17,418 phones pre-ordered (the objective was 15,000).
Just as they did for the Fairphone 1, Fairphone released details about costs for the Fairphone 2, which sold for an average price of €525. Despite its relatively high price compared to many phones (a similarly equipped "normal" phone cost about US$402–500), the margin on each phone sold was only €9, principally due to low sales volume and higher manufacturing costs than most phones. The price also funded a wide range of Fairphone's goals to make the phone more ethical, including recycling programs and partnerships for reduced usage of "blood minerals".
Sales
On 16 July 2015, pre-orders for Fairphone 2 became available. To order the components needed to assemble the first devices, as well as to generate the revenue needed to ensure continuous production, Fairphone initiated a crowdfunding campaign by setting a goal to achieve 15,000 pre-orders by the end of September. The goal was finally exceeded, reaching a total of 17,418 pre-orders before the pre-order period ended on 30 September. Production started in December 2015, aiming to ship all phones ordered during the crowdfunding campaign that month. However, issues in ramping up production caused a delay. The last pre-ordered device was shipped on 8 February 2016. On 26 May 2016, Fairphone reported that their milestone of selling 40,000 of the Fairphone 2 had been reached and that all phones ordered before that date had been shipped.
Discontinuation
On January 9th 2023 Fairphone announced that, after March 2023, the Fairphone 2 would stop receiving updates. Fairphone released the final update for the Fairphone 2 on March 7, 2023. Though parts for the phone are still available, the supply is limited.
See also
Modular smartphone, the concept of the phone for which components can be replaced
List of open-source mobile phones, phones with open-source operating system
Sailfish OS, an operating system based on Linux as an alternative to Android
Project Ara, a project by Google to create a low-price modular phone. Discontinued in September 2016
Footnotes
References
External links
Video of the Fairphone 2 being disassembled and reassembled
Fair trade brands
Android (operating system) devices
Ubuntu Touch devices
Fairphone smartphones
Modular smartphones
Mobile phones with user-replaceable battery
Mobile phones introduced in 2015 | Fairphone 2 | [
"Engineering"
] | 1,335 | [
"Modular design",
"Modular smartphones"
] |
47,316,194 | https://en.wikipedia.org/wiki/Jaw-Shen%20Tsai | Jaw-Shen Tsai ( Tsai Jaw-Shen, born February 8, 1952, in Taipei, Taiwan) is a Taiwanese physicist. He is a professor at the Tokyo University of Science and a team leader of the Superconducting Quantum Simulation Research Team at the Center for Emergent Matter Science (CEMS) within RIKEN. He has contributed to the area of condensed matter physics in both its fundamental physical aspects and its technological applications. He has recently been working on experiments connected to quantum coherence in Josephson systems. In February 2014, he retired from NEC Corporation, after 31 years of employment. He is a fellow of the American Physical Society as well as the Japan Society of Applied Physics.
Education and Work
Jaw-Shen Tsai obtained a Bachelor of Arts degree in Physics (1975) at University of California at Berkeley and a Ph.D. (1983) at the State University of New York at Stony Brook.
He has held the following positions:
1983 Research Scientist, Microelectronics Research Laboratories, NEC
2001 Fellow, Nano Electronics Research Laboratories, NEC
2001 Team Leader, Macroscopic Quantum Coherence Team, RIKEN
2012 Group Director, Single Quantum Dynamics Research Group, RIKEN
2013 Team Leader, Macroscopic Quantum Coherence Research Team, Quantum Information Electronics Division, RIKEN Center for Emergent Matter Science
2014 Team Leader, Superconducting Quantum Simulation Research Team, Quantum Information Electronics Division, RIKEN Center for Emergent Matter Science (-present)
2015 Professor, Tokyo University of Science (-present)
Honors and awards
2000 Fellow, American Physical Society
2004 Nishina Memorial Prize
2007 Honorary Professor, National Chiao Tung University
2008 Simon Memorial Prize (with Yasunobu Nakamura)
2010 Fellow, Japan Society of Applied Physics
2013 Quantum Innovator Award
2014 The 11th (with Yasunobu Nakamura)
2018 Medal with Purple Ribbon
2021 Asahi Prize (with Yasunobu Nakamura)
References
External links
Center for Emergent Matter Science at RIKEN http://www.riken.jp/en/research/labs/cems/
Quantum Cybernetics at RIKEN http://www.riken.jp/Qcybernetics/en/1_overview/index.html
Supeconducting Quantum Computing at FIRST, National Institute of Informatics http://www.nii.ac.jp/qis/first-quantum/e/subgroups/superconductingQcom/researcher.html
Department of Physics at Tokyo University of Science http://www.rs.tus.ac.jp/tsai/
1952 births
20th-century Taiwanese physicists
Quantum physicists
Living people
NEC people
Riken personnel
Stony Brook University alumni
Academic staff of Tokyo University of Science
UC Berkeley College of Letters and Science alumni
Taiwanese expatriates in Japan
Scientists from Taipei
Fellows of the American Physical Society
21st-century Taiwanese physicists
Taiwanese expatriates in the United States
Recipients of the Medal with Purple Ribbon
Foreign educators in Japan | Jaw-Shen Tsai | [
"Physics"
] | 608 | [
"Quantum physicists",
"Quantum mechanics"
] |
47,318,223 | https://en.wikipedia.org/wiki/Kepler-452b | Kepler-452b (sometimes quoted to be an Earth 2.0 or Earth's Cousin based on its characteristics; also known by its Kepler object of interest designation KOI-7016.01) is a candidate super-Earth exoplanet orbiting within the inner edge of the habitable zone of the sun-like star Kepler-452 and is the only planet in the system discovered by the Kepler space telescope. It is located about from Earth in the constellation of Cygnus.
Kepler-452b orbits its star at a distance of from its host star (nearly the same distance as Earth from the Sun), with an orbital period of roughly 385 days, has a mass at least five times that of Earth, and has a radius of around 1.5 times that of Earth. It is the first potentially rocky super-Earth planet discovered orbiting within the habitable zone of a very Sun-like star. However, it is unknown if it is entirely habitable, as it is receiving slightly more energy from its star than Earth and could be subjected to a runaway greenhouse effect.
The Kepler space telescope identified the exoplanet, and its discovery was announced by NASA on 23 July 2015. The planet is about away from the Solar System. At the speed of the New Horizons spacecraft, at about , it would take approximately 30 million years to get there.
Physical characteristics
Mass, radius and temperature
Kepler-452b has a probable mass five times that of Earth, and its surface gravity is nearly twice as much as Earth's, though calculations of mass for exoplanets are only rough estimates. If it is a terrestrial planet, it is most likely a super-Earth with many active volcanoes due to its higher mass and density. The clouds on the planet would be thick and misty, covering much of the surface as viewed from space.
The planet takes 385 Earth days to orbit its star. Its radius is 50% larger than Earth's, and lies within the conservative habitable zone of its parent star. It has an equilibrium temperature of , a little warmer than Earth.
Host star
The host star, Kepler-452, is a G-type and has about the same mass as the sun, only 3.7% more massive and 11% larger. It has a surface temperature of 5757 K, nearly the same as the Sun, which has a surface temperature of 5778 K. The star's age is estimated to be about 6 billion years old, about 1.5 billion years older than the Sun, which is estimated to have existed for 4.6 billion years. Kepler-452b has been in Kepler-452's habitable zone for most of its existence, a duration just over six billion years.
From the surface of Kepler-452b, its star would look almost identical to the Sun as viewed from the Earth. The star's apparent magnitude, or how bright it appears from Earth's perspective, is 13.426; therefore, it is too dim to be seen with the naked eye.
Orbit
Kepler-452b orbits its host star with an orbital period of 385 days and an orbital radius of about 1.04 AU, nearly the same as Earth's (1 AU). Kepler-452b is most likely not tidally locked and has a circular orbit. Its host star, Kepler-452, is about 20% more luminous than the Sun (L = 1.2 ).
Potential habitability
It is not known if Kepler-452b is a rocky planet but based on its small radius, Kepler-452b is likely to be rocky. It is not clear if Kepler-452b offers habitable environments. It orbits a G2V-type star, like the Sun, which is 20% more luminous, with nearly the same temperature and mass. However, the star is roughly 6 billion years old, making it 1.5 billion years older than the Sun. At this point in its star's evolution, Kepler-452b is currently receiving 10% more energy from its parent star than Earth is currently receiving from the Sun. If Kepler-452b is a rocky planet, it may be subject to a runaway greenhouse effect similar to that seen on Venus.
"Delayed" runaway greenhouse effect
However, due to the planet Kepler-452b being 50 percent bigger in terms of size, it is likely to have an estimated mass of 5 , which could allow it to hold on to any oceans it may have for a longer period, preventing Kepler-452b from succumbing to runaway greenhouse effect for another 500 million years. This, in turn, would be accompanied by the carbonate–silicate cycle being "buffered", extending its lifetime due to increased volcanic activity on Kepler-452b. This could allow any potential life on the surface to inhabit the planet for another 500–900 million years before the habitable zone is pushed beyond Kepler-452b's orbit.
Discovery and follow-up studies
In 2009, NASA's Kepler space telescope was observing stars on its photometer, the instrument it uses to detect transit events, in which a planet crosses in front of and dims its host star for a brief and roughly regular time. In this last test, Kepler observed stars in the Kepler Input Catalog, including Kepler-452; the preliminary light curves were sent to the Kepler science team for analysis, who chose obvious planetary companions from the bunch for follow-up by other telescopes. Observations for the potential exoplanet candidates took place between 13 May 2009 and 17 March 2012. Kepler-452b exhibited a transit that occurred roughly every 385 days, and it was eventually concluded that a planetary body was responsible. The discovery was announced by NASA on 23 July 2015.
At a distance of nearly , Kepler-452b is too remote for current telescopes or the next generation of planned telescopes to determine its true mass or whether it has an atmosphere. The Kepler space telescope focused on a single small region of the sky but next-generation planet-hunting space telescopes, such as TESS and CHEOPS, will examine nearby stars throughout the sky with follow up studies planned for these closer exoplanets by the James Webb Space Telescope and future large ground-based telescopes to analyze their atmospheres, determine masses, and infer compositions.
A study in 2018 by Mullally et al. claimed that statistically, Kepler-452b has not been proven to exist and must still be considered a candidate. However, Kepler-452b is still a possible planet and has not been shown to be a false positive.
SETI targeting
Scientists with the SETI (Search for Extraterrestrial Intelligence Institute) have already begun targeting Kepler-452b, the first near-Earth-size world found in the habitable zone of a Sun-like star. SETI Institute researchers are using the Allen Telescope Array, a collection of 6-meter (20 feet) telescopes in the Cascade Mountains of California, to scan for radio transmissions from Kepler-452b. As of July 2015, the array has scanned the exoplanet on over 2 billion frequency bands, with no result. The telescopes will continue to scan over a total of 9 billion channels, searching for alien radio analysis.
Observation and exploration
Kepler-452b is from Earth. The fastest current spacecraft, the New Horizons uncrewed probe that passed Pluto in July 2015, travels at just . At that speed, it would take a spacecraft about 26 million years to reach Kepler-452b from Earth, if it were going in that direction.
Gallery
See also
List of largest exoplanets
List of potentially habitable exoplanets
Superhabitable world
References
External links
NASA – Mission overview
NASA – Kepler Discoveries – Summary Table
Habitable Exoplanets Catalog at UPR-Arecibo.
Discovery and Validation of Kepler-452b: A 1.6-R🜨 Super-Earth Exoplanet in the Habitable Zone of a G2 Star
452b
Exoplanets discovered in 2015
Kepler-452
Super-Earths in the habitable zone
Terrestrial planets
Exoplanets in the habitable zone
Super-Earths
Transiting exoplanets
Cygnus (constellation)
Exoplanet candidates | Kepler-452b | [
"Astronomy"
] | 1,697 | [
"Cygnus (constellation)",
"Constellations"
] |
47,318,234 | https://en.wikipedia.org/wiki/Penicillium%20ranomafanaense | Penicillium ranomafanaense is a species of fungus in the genus Penicillium which isolated from soil in Ranomafana in Madagascar.
References
ranomafanaense
Fungi described in 2014
Fungus species | Penicillium ranomafanaense | [
"Biology"
] | 47 | [
"Fungi",
"Fungus species"
] |
47,318,237 | https://en.wikipedia.org/wiki/Action%20Center | Action Center is a notification center included with Windows Phone 8.1, Windows 10 and Windows 10 Mobile. It was introduced with Windows Phone 8.1 in July 2014, and was introduced to the desktop with the launch of Windows 10 on July 29, 2015.
The Action Center replaces the charms in Windows 10.
The Action Center was replaced with Quick Settings and the Notification Center in Windows 11.
Features
Action Center allows for four quick settings, and in Windows 10 users can expand the view to show all of the quick settings. Notifications are sorted into categories by app, and users can swipe right to clear notifications. Action Center also supports actionable notifications starting with Windows 10. In the mobile version, the user can swipe from the top to the bottom to invoke Action Center, and further features introduced in Windows Phone 8.1 include the ability to change simple settings such as volume controls. The new notifications area's design allows the user to for example change wireless networks, turn Bluetooth and Airplane Mode on or off, and access "Driving Mode" from four customisable boxes at the top of the screen, while beneath these four horizontally placed boxes include recent text messages and social integration. On the desktop version, the user can invoke Action Center by clicking on its icon on the taskbar (at the lower right corner of the screen), or by swiping from the right.
Microsoft announced at Microsoft Build 2016 that Cortana would be able to mirror notifications between the Actions Centers of Windows 10 Mobile and Windows 10, and Cortana would also be able to synchronize notifications from Android devices to the Windows 10 Action Center.
See also
Notification Center (iOS and OS X)
Notification service
References
Windows 10
Windows Phone
Windows Phone software
Action Centre | Action Center | [
"Technology"
] | 364 | [
"Computing stubs"
] |
47,318,483 | https://en.wikipedia.org/wiki/Kepler-452 | Extrasolar PlanetsEncyclopaediadata
Kepler-452 is a G-type main-sequence star located about 1,810 light-years away from Earth in the Cygnus constellation. Although similar in temperature to the Sun, it is 20% brighter, 3.7% more massive and 11% larger. Alongside this, the star is approximately six billion years old and possesses a high metallicity.
Nomenclature and history
Prior to Kepler observation, Kepler-452 had the 2MASS catalogue number 2MASS 19440088+4416392. In the Kepler Input Catalog, it has the designation of KIC 8311864. When it was found to have a transiting planet candidate, it was given the Kepler object of interest number of KOI-7016.
Planetary candidates were detected around the star by NASA's Kepler Mission, a mission tasked with discovering planets in transit around their stars. The transit method that Kepler uses involves detecting dips in brightness of stars. These dips in brightness can be interpreted as planets whose orbits pass in front of their stars from the perspective of Earth, although other phenomena can also be responsible which is why the term "planetary candidate" is used.
Following the acceptance of the discovery paper, the Kepler team referred to the star as Kepler-452, which is the normal procedure for naming exoplanets discovered by the spacecraft. Hence, this is the name usually used by the public to refer to the star and its planet.
Candidate planets that are associated with stars studied by the Kepler Mission are assigned the designations ".01", ".02", and so on, after the star's name, in the order of discovery. If planet candidates are detected simultaneously, then the ordering follows the order of orbital periods from shortest to longest. Following these rules, there was only one candidate planet detected, with an orbital period of 384.843 days. The name Kepler-452 derives directly from the fact that the star is the catalogued 452nd star discovered by Kepler to have confirmed planets.
The designation b, derives from the order of discovery. The designation of b is given to the first planet orbiting a given star, followed by the other lowercase letters of the alphabet. In the case of Kepler-452, there was only one planet, so only the letter b is used.
Stellar characteristics
Kepler-452 is a G-type star that is approximately 104% the mass of and 111% the radius of the Sun. It has a temperature of 5757 K and is roughly 6 billion years old. In comparison, the Sun is about 4.6 billion years old and has a temperature of 5778 K.
The star is metal-rich, with a metallicity (Fe/H) of about 0.21, or about 162% of the amount of iron and other heavier metals found in the Sun. The star's luminosity is somewhat normal for a star like Kepler-452, with a luminosity of around 120% of that of the solar luminosity.
The star's apparent magnitude, or how bright it appears from Earth's perspective, is 13.426. Therefore, it is too dim to be seen with the naked eye.
Planetary system
The star hosts one unconfirmed exoplanet, Kepler-452b, discovered in July 2015 by the Kepler spacecraft. This planet is mostly known for its characteristics similar to Earth, most notably its size, orbit and stellar flux. It is the first potentially rocky super-Earth planet discovered orbiting within the habitable zone and the abiogenesis zone of a star very similar to the Sun. It may even have a surface temperature similar to that of Earth (the planet has an equilibrium temperature of approximately (Earth's equilibrium temperature is only 10 K cooler than this). However, its star is 6 billion years old (roughly 1.5 billion years older than the Sun). Due to this, Kepler-452b is receiving roughly 10% more stellar radiation than the Earth does today. If Kepler-452b is a rocky planet, it might be subject to a runaway greenhouse effect. However, because of its mass (estimated to be about 5 ), it may be able to prevent succumbing to the runaway greenhouse for a limited amount of time (at most about 500 million years). Nevertheless, the planet is one of the most Earth-like planets discovered so far by the Kepler team. Both the Earth and Kepler-452b are at just the right distances from their stars so that water can be liquid, at a temperature between 0 °C and 100 °C.
Sun comparison
This table compares the Sun to Kepler-452.
References
J19440088+4416392
Cygnus (constellation)
G-type main-sequence stars
7016
Planetary systems with one confirmed planet
TIC objects | Kepler-452 | [
"Astronomy"
] | 999 | [
"Cygnus (constellation)",
"Constellations"
] |
47,318,486 | https://en.wikipedia.org/wiki/Penicillium%20raphiae | Penicillium raphiae is a species of fungus in the genus Penicillium which was isolated from agricultural soil of the Ulleung Island in Korea.
References
Further reading
raphiae
Fungi described in 2011
Fungus species | Penicillium raphiae | [
"Biology"
] | 48 | [
"Fungi",
"Fungus species"
] |
47,319,144 | https://en.wikipedia.org/wiki/Denso%20mapcode | The Denso MapCode system is a spatial reference system (not to be confused with the international mapcode system, a different spatial reference system). Denso MapCodes are 7- to 10-digit codes identifying specific 900-square-meter areas in Japan.
History
The Denso MapCode system was developed in 1997 by Denso Corporation for easy identification of any location in Japan by Japanese navigation systems. Car navigation systems are unable to identify locations for which addresses or telephone numbers are not available or house numbers, like in Japan, are not sequential. The Denso MapCode system enables accurate pinpointing by number, predetermined according to latitude and longitude.
The use of MapCodes is free to end users but corporations wanting to commercialise it will need to sign a contract with Denso and pay a fee. In Japan, car navigation system suppliers such as Denso itself, Clarion, Kenwood, Fujitsu Ten, Sony, Panasonic, Pioneer and Alpine Electronics have adopted the system and Toyota, Honda, Nissan, Fuji Heavy Industries, BMW Japan, General Motors Japan, Jaguar Japan and Land Rover Japan have introduced it in their vehicles.
Design principles
The Denso MapCode system divided Japan into 1162 zones, each zone into 900 blocks, and each block into 900 areas. A Denso MapCode number consists of the zone number (up to 4 digits), the block number (always 3 digits) and the area number (always 3 digits), a numeric code of up to 10 digits.
As the MapCode numbers proved too coarse for certain situations (this first version identified an area with a radius of about 100 meters ), the system was extended in 2004: by adding an asterisk and two extra digits, a specific cell of 9 square meters can be identified within an area. The design of the division in blocks is graphically explained on the website of Denso.
Application
Unfortunately, neither Garmin nor TomTom publish their own car navigation maps for Japan, although a third-party map for Garmin is available from UUD. Nowadays Japanese car rental companies offer on request at the time of reservation a rental car with a multi-language car navigation system. Navigation is not usually done by entering the destination street address, but by entering the telephone number or the Denso MapCode of the destination address.
Before August 2016, finding a Denso MapCode of a Japanese address involved 6 steps on the website http://mapion.co.jp in the Japanese language. Luckily, new alternatives such as http://japanmapcode.com/en or https://mapcodejapan.com uses Google maps and displays the mapcode for any address or GPS-coordinate entered. You can even point at a location on the map and the website displays the address and mapcode.
Furthermore, on October 18, 2016, Denso has launched the free smartphone app Drive! Nippon, for iOS and Android. This app, bilingual in Japanese and English, will show the MapCode if you know the street address of GPS-coordinate. If you point at a location on the map, it will show the street address and GPS-coordinate and produces the MapCode. Internet connection is required.
References
External links
applet showing Denso MapCode in Japan
Web App for finding Denso MapCodes
Geographic coordinate systems | Denso mapcode | [
"Mathematics"
] | 678 | [
"Geographic coordinate systems",
"Coordinate systems"
] |
47,319,644 | https://en.wikipedia.org/wiki/Error%20level%20analysis | Error level analysis (ELA) is the analysis of compression artifacts in digital data with lossy compression such as JPEG.
Principles
When used, lossy compression is normally applied uniformly to a set of data, such as an image, resulting in a uniform level of compression artifacts.
Alternatively, the data may consist of parts with different levels of compression artifacts. This difference may arise from the different parts having been repeatedly subjected to the same lossy compression a different number of times, or the different parts having been subjected to different kinds of lossy compression. A difference in the level of compression artifacts in different parts of the data may therefore indicate that the data has been edited.
In the case of JPEG, even a composite with parts subjected to matching compressions will have a difference in the compression artifacts.
In order to make the typically faint compression artifacts more readily visible, the data to be analyzed is subjected to an additional round of lossy compression, this time at a known, uniform level, and the result is subtracted from the original data under investigation. The resulting difference image is then inspected manually for any variation in the level of compression artifacts. In 2007, N. Krawetz denoted this method "error level analysis".
Additionally, digital data formats such as JPEG sometimes include metadata describing the specific lossy compression used. If in such data the observed compression artifacts differ from those expected from the given metadata description, then the metadata may not describe the actual compressed data, and thus indicate that the data have been edited.
Limitations
By its nature, data without lossy compression, such as a PNG image, cannot be subjected to error level analysis. Consequently, since editing could have been performed on data without lossy compression with lossy compression applied uniformly to the edited, composite data, the presence of a uniform level of compression artifacts does not rule out editing of the data.
Additionally, any non-uniform compression artifacts in a composite may be removed by subjecting the composite to repeated, uniform lossy compression. Also, if the image color space is reduced to 256 colors or less, for example, by conversion to GIF, then error level analysis will generate useless results.
More significant, the actual interpretation of the level of compression artifacts in a given segment of the data is subjective, and the determination of whether editing has occurred is therefore not robust.
Controversy
In May 2013, Dr Neal Krawetz used error level analysis on the 2012 World Press Photo of the Year and concluded on his Hacker Factor blog that it was "a composite" with modifications that "fail to adhere to the acceptable journalism standards used by Reuters, Associated Press, Getty Images, National Press Photographer's Association, and other media outlets". The World Press Photo organizers responded by letting two independent experts analyze the image files of the winning photographer and subsequently confirmed the integrity of the files. One of the experts,
Hany Farid, said about error level analysis that "It incorrectly labels altered images as original and incorrectly labels original images as altered with the same likelihood". Krawetz responded by clarifying that "It is up to the user to interpret the results. Any errors in identification rest solely on the viewer".
In May 2015, the citizen journalism team Bellingcat wrote that error level analysis revealed that the Russian Ministry of Defense had edited satellite images related to the Malaysia Airlines Flight 17 disaster. In a reaction to this, image forensics expert Jens Kriese said about error level analysis: "The method is subjective and not based entirely on science", and that it is "a method used by hobbyists". On his Hacker Factor Blog, the inventor of error level analysis Neal Krawetz criticized both Bellingcat's use of error level analysis as "misinterpreting the results" but also on several points Jens Kriese's "ignorance" regarding error level analysis.
See also
Image analysis
References
External links
Image Forensics : Error Level Analysis
FotoForensics
Data analysis
Data compression
Computer vision | Error level analysis | [
"Engineering"
] | 810 | [
"Artificial intelligence engineering",
"Packaging machinery",
"Computer vision"
] |
47,320,410 | https://en.wikipedia.org/wiki/Mogul%20%28company%29 | Mogul is a global diversity recruitment company, founded by American entrepreneurs Tiffany Pham and David Pham.
The company is backed by investors SoftBank Group and Hearst corporation, and provides diversity recruitment software and diverse executive and board search services to Fortune 1000 clients including Chanel, UBS, Bristol Myers Squibb, Intuit, EBay, Nike, Inc., and Amazon (company).
Awards and recognition
In 2014, Mogul was the winner of the Cadillac "IVY Innovator Award.” Mogul was also honored by the United Nations, Forbes, Inc. (magazine), and Entrepreneur (magazine).
In 2016, Mogul launched the #IAmAMogul campaign featuring Chelsea Clinton and Mayor of Paris Anne Hidalgo to "inspire all women to realize that they too can be moguls, and that they have the power to shape the world through their voices and actions."
In 2020, Mogul became the subject of a case study by Harvard Business School called "Redefining Mogul."
Mogul was honored by the World Economic Forum as a "Technology Pioneer" of 2023.
References
External links
Mogul
Social media | Mogul (company) | [
"Technology"
] | 234 | [
"Computing and society",
"Social media"
] |
47,321,247 | https://en.wikipedia.org/wiki/Glaeser%27s%20continuity%20theorem | In mathematical analysis, Glaeser's continuity theorem is a characterization of the continuity of the derivative of the square roots of functions of class . It was introduced in 1963 by Georges Glaeser, and was later simplified by Jean Dieudonné.
The theorem states: Let be a function of class in an open set U contained in , then is of class in U if and only if its partial derivatives of first and second order vanish in the zeros of f.
References
Theorems in analysis | Glaeser's continuity theorem | [
"Mathematics"
] | 103 | [
"Theorems in mathematical analysis",
"Mathematical analysis",
"Mathematical problems",
"Mathematical theorems"
] |
47,321,473 | https://en.wikipedia.org/wiki/Kolmogorov%E2%80%93Arnold%20representation%20theorem | In real analysis and approximation theory, the Kolmogorov–Arnold representation theorem (or superposition theorem) states that every multivariate continuous function can be represented as a superposition of continuous single-variable functions.
The works of Vladimir Arnold and Andrey Kolmogorov established that if f is a multivariate continuous function, then f can be written as a finite composition of continuous functions of a single variable and the binary operation of addition. More specifically,
where and .
There are proofs with specific constructions.
It solved a more constrained form of Hilbert's thirteenth problem, so the original Hilbert's thirteenth problem is a corollary. In a sense, they showed that the only true continuous multivariate function is the sum, since every other continuous function can be written using univariate continuous functions and summing.
History
The Kolmogorov–Arnold representation theorem is closely related to Hilbert's 13th problem. In his Paris lecture at the International Congress of Mathematicians in 1900, David Hilbert formulated 23 problems which in his opinion were important for the further development of mathematics. The 13th of these problems dealt with the solution of general equations of higher degrees. It is known that for algebraic equations of degree 4 the solution can be computed by formulae that only contain radicals and arithmetic operations. For higher orders, Galois theory shows us that the solutions of algebraic equations cannot be expressed in terms of basic algebraic operations. It follows from the so called Tschirnhaus transformation that the general algebraic equation
can be translated to the form . The Tschirnhaus transformation is given by a formula containing only radicals and arithmetic operations and transforms. Therefore, the solution of an algebraic equation of degree can be represented as a superposition of functions of two variables if and as a superposition of functions of variables if . For the solution is a superposition of arithmetic operations, radicals, and the solution of the equation
A further simplification with algebraic transformations seems to be impossible which led to Hilbert's conjecture that "A solution of the general equation of degree 7 cannot be represented as a superposition of continuous functions of two variables". This explains the relation of Hilbert's thirteenth problem to the representation of a higher-dimensional function as superposition of lower-dimensional functions. In this context, it has stimulated many studies in the theory of functions and other related problems by different authors.
Variants
A variant of Kolmogorov's theorem that reduces the number of
outer functions is due to George Lorentz. He showed in 1962 that the outer functions can be replaced by a single function . More precisely, Lorentz proved the existence of functions , , such that
David Sprecher replaced the inner functions by one single inner function with an appropriate shift in its argument. He proved that there exist real values , a continuous function , and a real increasing continuous function with , for , such that
Phillip A. Ostrand generalized the Kolmogorov superposition theorem to compact metric spaces. For let be compact metric spaces of finite dimension and let . Then there exists continuous functions and continuous functions such that any continuous function is representable in the form
Kolmogorov-Arnold representation theorem and its aforementioned variants also hold for discontinuous multivariate functions.
Limitations
The theorem does not hold in general for complex multi-variate functions, as discussed here. Furthermore, the non-smoothness of the inner functions and their "wild behavior" has limited the practical use of the representation, although there is some debate on this.
Applications
In the field of machine learning, there have been various attempts to use neural networks modeled on the Kolmogorov–Arnold representation. In these works, the Kolmogorov–Arnold theorem plays a role analogous to that of the universal approximation theorem in the study of multilayer perceptrons.
Proof
Here one example is proved. This proof closely follows. A proof for the case of functions depending on two variables is given, as the generalization is immediate.
Setup
Let be the unit interval .
Let be the set of continuous functions of type . It is a function space with supremum norm (it is a Banach space).
Let be a continuous function of type , and let be the supremum of it on .
Let be a positive irrational number. Its exact value is irrelevant.
We say that a 5-tuple is a Kolmogorov-Arnold tuple if and only if any there exists a continuous function , such that In the notation, we have the following:
Proof
Fix a . We show that a certain subset is open and dense: There exists continuous such that , and We can assume that with no loss of generality.
By continuity, the set of such 5-tuples is open in . It remains to prove that they are dense.
The key idea is to divide into an overlapping system of small squares, each with a unique address, and define to have the appropriate value at each address.
Grid system
Let . For any , for all large , we can discretize into a continuous function satisfying the following properties:
is constant on each of the intervals .
These values are different rational numbers.
.
This function creates a grid address system on , divided into streets and blocks. The blocks are of form .
Since is continuous on , it is uniformly continuous. Thus, we can take large enough, so that varies by less than on any block.
On each block, has a constant value. The key property is that, because is irrational, and is rational on the blocks, each block has a different value of .
So, given any 5-tuple , we construct such a 5-tuple . These create 5 overlapping grid systems.
Enumerate the blocks as , where is the -th block of the grid system created by . The address of this block is , for any . By adding a small and linearly independent irrational number (the construction is similar to that of the Hamel basis) to each of , we can ensure that every block has a unique address.
By plotting out the entire grid system, one can see that every point in is contained in 3 to 5 blocks, and 2 to 0 streets.
Construction of g
For each block , if on all of then define ; if on all of then define . Now, linearly interpolate between these defined values. It remains to show this construction has the desired properties.
For any , we consider three cases.
If , then by uniform continuity, on every block that contains the point . This means that on 3 to 5 of the blocks, and have an unknown value on 2 to 0 of the streets. Thus, we have givingSimilarly for .
If , then since , we still have
Baire category theorem
Iterating the above construction, then applying the Baire category theorem, we find that the following kind of 5-tuples are open and dense in : There exists a sequence of such that , , etc. This allows their sum to be defined: , which is still continuous and bounded, and it satisfies Since has a countable dense subset, we can apply the Baire category theorem again to obtain the full theorem.
Extensions
The above proof generalizes for -dimensions: Divide the cube into interlocking grid systems, such that each point in the cube is on to blocks, and to streets. Now, since , the above construction works.
Indeed, this is the best possible value.
A relatively short proof is given in via dimension theory.
In another direction of generality, more conditions can be imposed on the Kolmogorov–Arnold tuples.
The proof is given in.
(Vituškin, 1954) showed that the theorem is false if we require all functions to be continuously differentiable. The theorem remains true if we require all to be 1-Lipschitz continuous.
References
Sources
Andrey Kolmogorov, "On the representation of continuous functions of several variables by superpositions of continuous functions of a smaller number of variables", Proceedings of the USSR Academy of Sciences, 108 (1956), pp. 179–182; English translation: Amer. Math. Soc. Transl., "17: Twelve Papers on Algebra and Real Functions" (1961), pp. 369–373.
Vladimir Arnold, "On functions of three variables", Proceedings of the USSR Academy of Sciences, 114 (1957), pp. 679–681; English translation: Amer. Math. Soc. Transl., "28: Sixteen Papers on Analysis" (1963), pp. 51–54. SpringerLink
Vladimir Arnold, "On the representation of continuous functions of three variables as superpositions of continuous functions of two variables", Dokl. Akad. Nauk. SSSR 114:4 (1957), pp. 679–681 (in Russian) SpringerLink
Andrey Kolmogorov, "On the representation of continuous functions of several variables as superpositions of continuous functions of one variable and addition", (1957); English translation: Amer. Math. Soc. Transl., "28: Sixteen Papers on Analysis" (1963), PDF
Further reading
S. Ya. Khavinson, Best Approximation by Linear Superpositions (Approximate Nomography), AMS Translations of Mathematical Monographs (1997)
Theorems in real analysis
Functions and mappings
Theorems in approximation theory | Kolmogorov–Arnold representation theorem | [
"Mathematics"
] | 1,903 | [
"Theorems in mathematical analysis",
"Mathematical analysis",
"Functions and mappings",
"Theorems in real analysis",
"Mathematical objects",
"Theorems in approximation theory",
"Mathematical relations"
] |
47,321,570 | https://en.wikipedia.org/wiki/Valeria%20de%20Paiva | Valeria Correa Vaz de Paiva is a Brazilian mathematician, logician, and computer scientist.
Her work includes research on logical approaches to computation, especially using category theory,
knowledge representation and natural language semantics, and functional programming with a focus on foundations and type theories.
Education
De Paiva earned a bachelor's degree in mathematics in 1982, a master's degree in 1984 (on pure algebra) and completed a doctorate at the University of Cambridge in 1988, under the supervision of Martin Hyland. Her thesis introduced Dialectica spaces, a categorical way of constructing models of linear logic, based on Kurt Gödel's Dialectica interpretation.
Career and research
She worked for nine years at PARC in Palo Alto, California, and also worked at Rearden Commerce and Cuil before joining Nuance. She is an honorary research fellow in computer science at the University of Birmingham. She is currently on the Council of the Division for Logic, Methodology and Philosophy of Science and Technology of the International Union of History and Philosophy of Science and Technology (2020–2023).
Selected publications
Applied Category Theory in Chemistry, Computing, and Social Networks. (with Baez, Cho, Ciccala and Otter). Notices of the American Mathematical Society, vol. 69, number 2, February 2022.
Term Assignment for Intuitionistic Linear Logic. (with Benton, Bierman and Hyland). Technical Report 262, University of Cambridge Computer Laboratory. August 1992.
Lineales. (with J.M.E. Hyland) In "O que nos faz pensar" Special number in Logic of "Cadernos do Dept. de Filosofia da PUC", Pontificial Catholic University of Rio de Janeiro, April 1991.
A Dialectica-like Model of Linear Logic. In Proceedings of Category Theory and Computer Science, Manchester, UK, September 1989. Springer-Verlag LNCS 389 (eds. D. Pitt, D. Rydeheard, P. Dybjer, A. Pitts and A. Poigne).
The Dialectica Categories. In Proc of Categories in Computer Science and Logic, Boulder, CO, 1987. Contemporary Mathematics, vol 92, American Mathematical Society, 1989 (eds. J. Gray and A. Scedrov)
References
Year of birth missing (living people)
Living people
Brazilian mathematicians
Brazilian computer scientists
American computer scientists
Women logicians
Brazilian women computer scientists
Alumni of the University of Cambridge
Brazilian logicians
Category theorists
20th-century American mathematicians
21st-century American mathematicians
Scientists at PARC (company)
20th-century American women mathematicians
21st-century American women mathematicians
Brazilian expatriates in the United Kingdom | Valeria de Paiva | [
"Mathematics"
] | 545 | [
"Category theorists",
"Mathematical structures",
"Category theory"
] |
47,322,010 | https://en.wikipedia.org/wiki/PerfKitBenchmarker | PerfKit Benchmarker is an open source benchmarking tool used to measure and compare cloud offerings. PerfKit Benchmarker is licensed under the Apache 2 license terms. PerfKit Benchmarker is a community effort involving over 500 participants including researchers, academic institutions and companies together with the originator, Google.
General
PerfKit Benchmarker (PKB) is a community effort to deliver a repeatable, consistent, and open way of measuring Cloud Performance. It supports a growing list of cloud providers including: Alibaba Cloud, Amazon Web Services, CloudStack, DigitalOcean, Google Cloud Platform, Kubernetes, Microsoft Azure, OpenStack, Rackspace, IBM Bluemix (Softlayer). In addition to Cloud Providers to supports container orchestration including Kubernetes and Mesos and local "static" workstations and clusters of computers .
The goal is to create an open source living benchmark [framework] that represents how Cloud developers are building applications, evaluating Cloud alternatives, learning how to architect applications for each cloud. Living because it will change and morph quickly as developers change.
PerfKit Benchmarker measures the end to end time to provision resources in the cloud, in addition to reporting on the most standard metrics of peak performance, e.g.: latency, throughput, time-to-complete, IOPS. PerfKit Benchmarker reduces the complexity in running benchmarks on supported cloud providers by unified and simple commands. It's designed to operate via vendor provided command line tools.
PerfKit Benchmarker contains a canonical set of public benchmarks. All benchmarks are running with default/initial state and configuration (Not tuned to in favor of any providers). This provides a way to benchmark across cloud platforms, while getting a transparent view of application throughput, latency, variance, and overhead.
History
PerfKit Benchmarker (PKB) was started by Anthony F. Voellm, Alain Hamel, and Eric Hankland at Google in 2014. Once an initial "alpha" was in place Anthony F. Voellm and Ivan Santa Maria Filho built a community including ARM, Broadcom, Canonical, CenturyLink, Cisco, CloudHarmony, CloudSpectator, EcoCloud@EPFL, Intel, Mellanox, Microsoft, Qualcomm Technologies, Inc., Rackspace, Red Hat, Tradeworx Inc., and Thesys Technologies LLC.
This community worked together behind the scenes in a private GitHub project to create an open way to measure cloud performance. This community released the first public "beta" was released on February 11, 2015, and announced in a blog post at which point the GitHub project was open to everyone. After almost a year and with large adaption (600+ participants on GitHub) the V1.0.0 was released along with a detailed architectural design on December 10, 2015.
Benchmarks
A list of available benchmarks from PerfKitBenchmarker: (The latest set of benchmarks can be found at GitHub readme file.)
Industry participants
Since Google open sourced the PerfKitBenchmarker, it became a community effort from over 30 leading researchers, academic schools and industry companies. Those organizations include: ARM, Broadcom, Canonical, CenturyLink, Cisco, CloudHarmony, Cloud Spectator, EcoCloud@EPFL, Intel, Mellanox, Microsoft, Qualcomm Technologies, Rackspace, Red Hat, and Thesys Technologies. In addition, Stanford and MIT are leading quarterly discussions on default benchmarks and settings proposed by the community. EcoCloud@EPFL is integrating CloudSuite into PerfKit Benchmarker.
Example runs
Example run on Google Cloud Platform
$ ./pkb.py --cloud=GCP --project=<GCP project ID> --benchmarks=iperf --machine_type=f1-micro
Example run on AWS
$ ./pkb.py --cloud=AWS --benchmarks=iperf --machine_type=t1.micro
Example run on Azure
$ ./pkb.py --cloud=Azure --machine_type=ExtraSmall --benchmarks=iperf
Example run on Rackspace
$ ./pkb.py --cloud=Rackspace --machine_type=standard1 --benchmarks=iperf
Example run on a local machine
$ ./pkb.py --stack_vm_file=local_config.json --benchmarks=iperf
References
Cloud computing
Benchmarks (computing) | PerfKitBenchmarker | [
"Technology"
] | 986 | [
"Benchmarks (computing)",
"Computing comparisons",
"Computer performance"
] |
47,322,965 | https://en.wikipedia.org/wiki/Dilution%20ratio | In chemistry and biology, the dilution ratio and dilution factor are two related (but slightly different) expressions of the change in concentration of a liquid substance when mixing it with another liquid substance. They are often used for simple dilutions, one in which a unit volume of a liquid material of interest is combined with an appropriate volume of a solvent liquid to achieve the desired concentration. The diluted material must be thoroughly mixed to achieve the true dilution.
For example, in a solution with a 1:5 dilution ratio, entails combining 1 unit volume of solute (the material to be diluted) with 5 unit volumes of the solvent to give 6 total units of total volume.
In photographic development, dilutions are normally given in a '1+x' format. For example '1+49' would typically mean 1 part concentrate and 49 parts water, meaning a 500ml solution would require 10ml concentrate and 490ml water.
Dilution factor
The "dilution factor" is an expression which describes the ratio of the aliquot volume to the final volume. Dilution factor is a notation often used in commercial assays. For example, in solution with a 1/5 dilution factor (which may be abbreviated as x5 dilution), entails combining 1 unit volume of solute (the material to be diluted) with (approximately) 4 unit volumes of the solvent to give 5 units of total volume. The following formulas can be used to calculate the volumes of solute () and solvent () to be used:
where is the desired total volume, and is the desired dilution factor number (the number in the position of if expressed as " dilution factor" or " dilution").
However, some solutions and mixtures take up slightly less volume than their components.
In other areas of science such as pharmacy, and in non-scientific usage, a dilution is normally given as a plain ratio of solvent to solute. For large factors, this confusion makes only a minor difference, but in precise work it can be important to make clear whether dilution ratio or dilution factor is intended.
References
See also
Fraction (chemistry)
Concentration
Ternary plot
Concentration indicators
Ratios | Dilution ratio | [
"Mathematics"
] | 450 | [
"Arithmetic",
"Ratios"
] |
39,950,378 | https://en.wikipedia.org/wiki/Kepler-47b | Kepler-47b (also known as Kepler-47 (AB) b and by its Kepler Object of Interest designation KOI-3154.01) is an exoplanet orbiting the binary star system Kepler-47, the innermost of three such planets discovered by NASA's Kepler spacecraft. The system, also involving two other exoplanets, is located about 3,400 light-years (1,060 parsecs) away.
Characteristics
Mass, radius and temperature
Kepler-47b is a gas giant, an exoplanet that is near the same mass and radius as the planets Jupiter and Saturn. It has a temperature of . The planet has a radius of , and is thought to have no solid surface. It has a mass of .
Host stars
The planet orbits in a circumbinary orbit around a (G-type) and (M-type) binary star system. The stars orbit each other about every 7.45 days. The stars have masses of 1.04 and 0.35 and radii of 0.96 and 0.35 , respectively. They have temperatures of 5636 K and 3357 K. Based on the stellar characteristics and orbital dynamics, an estimated age of 4–5 billion years for the system is possible. In comparison, the Sun is about 4.6 billion years old and has a temperature of 5778 K. The primary star is somewhat metal-poor, with a metallicity ([Fe/H]) of −0.25, or 56% of the solar amount. The stars' luminosities () are 84% and 1% that of the Sun.
The apparent magnitude of the system, or how bright it appears from Earth's perspective, is about 15.8. Therefore, it is too dim to be seen with the naked eye.
Orbit
Kepler-47b orbits around its parent stars every 45 days at a distance of 0.29 AU from its stars (close to where Mercury orbits from the Sun, which is about 0.39 AU). It receives about 9.6 times as much sunlight that Earth does from the Sun.
Discovery
Kepler-47b, as well as Kepler-47c, was first discovered by scientists, from both NASA and the Tel-Aviv University in Israel, using the Kepler space telescope. Additionally, the planetary characteristics of both objects were identified by a team of astronomers at the University of Texas at Austin's McDonald observatory. Both planets were discovered after transiting their parent stars, and they both seem to be orbiting along the same plane.
Significance
Prior to the discovery of Kepler-47c, it was thought that binary stars with multiple planets could not exist. Gravitational issues caused by the parent stars would, it was believed, cause any circumbinary planets to either collide with each other, collide with one of the parent stars, or be flung out of orbit. However, this discovery shows that multiple planets can form around binary stars, even in their habitable zones; and while Kepler-47c is most likely unable to harbor life because it gas giant, other planets that could support life may orbit binary systems such as Kepler-47.
See also
List of extrasolar planet firsts
List of planets discovered by the Kepler spacecraft
References
Kepler-47
47c
Exoplanets discovered in 2012
Cygnus (constellation)
Circumbinary planets | Kepler-47b | [
"Astronomy"
] | 692 | [
"Cygnus (constellation)",
"Constellations"
] |
39,950,449 | https://en.wikipedia.org/wiki/Ed%20Scheinerman | Edward R. Scheinerman is an American mathematician, working in graph theory and order theory. He is a professor of applied mathematics, statistics, and computer science at Johns Hopkins University. His contributions to mathematics include Scheinerman's conjecture, now proven, stating that every planar graph may be represented as an intersection graph of line segments.
Scheinerman did his undergraduate studies at Brown University, graduating in 1980, and earned his Ph.D. in 1984 from Princeton University under the supervision of Douglas B. West. He joined the Johns Hopkins faculty in 1984, and since 2000 he has been an administrator there, serving as department chair, associate dean, vice dean for education, vice dean for graduate education, and vice dean for faculty (effective September 2019).
He is a two-time winner of the Mathematical Association of America's Lester R. Ford Award for expository writing, in 1991 for his paper "Random intervals" with Joyce Justicz and Peter Winkler, and in 2001 for his paper "When Close is Close Enough". In 1992 he became a fellow of the Institute of Combinatorics and its Applications, and in 2012 he became a fellow of the American Mathematical Society.
Selected publications
Books
Invitation to Dynamical Systems (Prentice Hall, 1996, reprinted by Dover Publications, 2012).
Fractional Graph Theory (With Daniel Ullman, Wiley, 1997, reprinted by Dover Publications, 2011).
Mathematics: A Discrete Introduction. (Brooks/Cole, 2000; 3rd edition, Cengage Learning, 2012).
C++ for mathematicians : an introduction for students and professionals (Chapman & Hall/CRC, 2006).
The Mathematics Lover's Companion: Masterpieces for Everyone (Yale University Press, 2017).
Papers
.
.
References
External links
Home page
Year of birth missing (living people)
Living people
20th-century American mathematicians
21st-century American mathematicians
Graph theorists
Brown University alumni
Princeton University alumni
Johns Hopkins University faculty
Fellows of the American Mathematical Society | Ed Scheinerman | [
"Mathematics"
] | 399 | [
"Mathematical relations",
"Graph theory",
"Graph theorists"
] |
39,950,774 | https://en.wikipedia.org/wiki/Plasmonic%20lens | In nano-optics, a plasmonic lens generally refers to a lens for surface plasmon polaritons (SPPs), i.e. a device that redirects SPPs to converge towards a single focal point. Because SPPs can have very small wavelength, they can converge into a very small and very intense spot, much smaller than the free space wavelength and the diffraction limit.
A simple example of a plasmonic lens is a series of concentric rings on a metal film. Any light that hits the film from free space at a 90-degree angle, known as the normal, will get coupled into a SPP (this part works like a diffraction grating coupler), and that SPP will be heading towards the center of the circles, which is the focal point. Another example is a tapered "dimple".
In 2007, a novel, or technologically new, plasmonic lenses and waveguide by modulating light a mesoscale dielectric structure on a metallic film with arrayed nano-slits, which have constant depth but variant widths. The slits transport electromagnetic energy in the form of SPPs in nanometer sized waveguides and provide desired phase adjustments for manipulating the beam of light. The scientists claim that it is an improvement over other subwavelength imaging techniques, such as "superlenses", where the object and image are confined to the near field.
These devices have been suggested for various applications that take advantage of the small size and high intensity of the SPPs at the focal point. These include photolithography, heat-assisted magnetic recording, microscopy, biophotonics, biological molecule sensors, and solar cells, as well as other applications.
The term "plasmonic lens" is also sometimes used to describe something different: Any free-space lens (i.e., a lens that focuses free-space light, rather than SPPs), that has something to do with plasmonics.
References
Further reading
Plasmonics
Biotechnology
Metamaterials
Lenses | Plasmonic lens | [
"Physics",
"Chemistry",
"Materials_science",
"Engineering",
"Biology"
] | 429 | [
"Plasmonics",
"Metamaterials",
"Materials science",
"Surface science",
"Biotechnology",
"Condensed matter physics",
"nan",
"Nanotechnology",
"Solid state engineering"
] |
39,951,483 | https://en.wikipedia.org/wiki/Tetrafluoroberyllate | Tetrafluoroberyllate or orthofluoroberyllate is an anion with the chemical formula . It contains beryllium and fluorine. This fluoroanion has a tetrahedral shape, with the four fluorine atoms surrounding a central beryllium atom. It has the same size, charge, and outer electron structure as sulfate . Therefore, many compounds that contain sulfate have equivalents with tetrafluoroberyllate. Examples of these are the langbeinites, and Tutton's salts.
Properties
The Be–F bond length is between 145 and 153 pm. The beryllium is sp3 hybridized, leading to a longer bond than in , where beryllium is sp hybridized. In trifluoroberyllates, there are actually tetrahedra arranged in a triangle, so that three fluorine atoms are shared on two tetrahedra each, resulting in a formula of .
In the tetrafluoroberyllates, the tetrahedra can rotate to various degrees. At room temperature, they are hindered from moving. But as temperature increases, they can rotate around the threefold axis, (i.e. a line through one fluorine atom and the beryllium atom) with a potential barrier of . At higher temperatures, the movement can become isotropic (not limited to rotation on one axis) with a potential barrier of .
Similar compounds have magnesium or zinc in a similar position as beryllium, e.g. (potassium tetrafluoromagnesate) or (ammonium tetrafluorozincate) but these are not as stable.
Tetrafluoroberyllate has a biological effect by inhibiting F-ATPase adenosine triphosphate producing enzymes in mitochondria and bacteria. It does this by attempting to react with adenosine diphosphate because it resembles phosphate. However once it does this it remains stuck in the F1 part of the enzyme and inhibits it from further function.
Simple salts
Sodium tetrafluoroberyllate has several crystalline forms. Below 220 °C it takes the same form as orthorhombic olivine, and this is called γ phase. Between 220 °C and 320 °C it is in the α′ form. When temperature is raised above 320 °C it changes to the hexagonal α form. When cooled the α′ form changes to β form at 110 °C and this can be cooled to 70 °C before changing back to the γ form. It can be formed by melting sodium fluoride and beryllium fluoride. The gas above molten sodium tetrafluoroberyllate contains and NaF gas.
Lithium tetrafluoroberyllate takes on the same crystal form as the mineral phenacite. As a liquid it is proposed for the molten salt reactor, in which it is called FLiBe. The liquid salt has a high specific heat, similar to that of water. The molten salt has a very similar density to the solid. The solid has continuous void channels through it, which reduces its density. can be crystallised from aqueous solution using and LiCl.
Potassium tetrafluoroberyllate has the same structure as anhydrous potassium sulfate, as does rubidium and caesium tetrafluoroberyllate. Potassium tetrafluoroberyllate can make solid solutions with potassium sulfate. It can be used as a starting point to make the non-linear optic crystal which has the highest power handling capacity and shortest UV performance of any borate. It is quite soluble in water, so beryllium can be extracted from soil in this form.
Ammonium tetrafluoroberyllate decomposes on heating by losing vapour, progressively forming , then and finally .
Thallium tetrafluoroberyllate can be made by dissolving beryllium fluoride and thallium carbonate together in hydrofluoric acid and then evaporating the solution.
Radium tetrafluoroberyllate is used as a standard neutron source. The alpha particles from the radium cause neutrons to be emitted from the beryllium. It is precipitated from a radium chloride solution mixed with potassium tetrafluoroberyllate.
Magnesium tetrafluoroberyllate can be precipitated from a hot saturated solution of ammonium tetrafluoroberyllate and a magnesium salt. However, if the temperature reaches boiling point is precipitated instead.
Calcium tetrafluoroberyllate resembles zircon in the way it melts and crystallises.
Strontium tetrafluoroberyllate can be made in several forms. The γ form is produced by cooling a melt of and and the β form is made by precipitating from a water solution. When melted and heated to 850–1145 °C, gas evaporates leaving behind molten .
The barium tetrafluoroberyllate is very insoluble and can be used for gravimetric analysis of beryllium.
is an acid that can be produced from and HCl. It only exists in aqueous solution.
Triglycine tetrafluoroberyllate (TGFB) is ferroelectric with a transition point of 70 °C. The crystals can be formed by dissolving in water, adding HF and then glycine. When the solution is cooled triglycine tetrafluoroberyllate forms. and in the solution reduce growth on the 001 direction so that tabular shaped crystals of TGFB form. The thallium compound can cut growth on the 001 axis by 99%.
Double salts
Tuttons salts
The Tuttons salt (NH4)2Mn(BeF4)2·6(H2O) is made from a solution of NH4BeF3 mixed with NH4MnF3.
The equivalent of alums are hard to make because the trivalent ion will often form a complex with fluoride in preference to the beryllium fluoride. However the violet coloured acid and rubidium chrome alum exist at chilly temperatures for a few hours.
Tutton's salts (also called schoenites) containing magnesium with fluoroberyllate are difficult to produce, as the solutions tend to precipitate insoluble MgF2.
Alums
Tetrafluoroberyllate salts equivalent to alums also exist with formula MABF4·12H2O, where M is univalent, and A trivalent. These are not common as fluoride often form insoluble products with the trivalent ions. Methods to produce these include evaporating mixed fluoride solutions under reduced pressure at 0 °C, or dissolving beryllium and other metal hydroxides in hydrofluoric acid at room temperature, cooled, and them mixing with cold ethyl alcohol, causing cooling and crystallisation. The unit cell dimensions are slightly smaller (by 0.03–0.05 Å) than the corresponding sulfate alums.
References
Beryllium compounds
Fluorine compounds
Anions
Fluorometallates | Tetrafluoroberyllate | [
"Physics",
"Chemistry"
] | 1,509 | [
"Ions",
"Matter",
"Anions"
] |
39,952,681 | https://en.wikipedia.org/wiki/John%20Desmond%20Bernal%20Prize | The John Desmond Bernal Prize is an award given annually by the Society for Social Studies of Science (4S) to scholars judged to have made a distinguished contribution to the interdisciplinary field of Science and Technology Studies (STS). The award was launched in 1981, with the support of Eugene Garfield.
The award is named after the scientist John Desmond Bernal.
Award recipients
Source: Society for Social Studies of Science
See also
List of social sciences awards
References
External links
Society for Social Studies of Science
Science and technology studies
Sociology of science | John Desmond Bernal Prize | [
"Technology"
] | 106 | [
"Science and technology studies"
] |
39,952,976 | https://en.wikipedia.org/wiki/Analytically%20unramified%20ring | In algebra, an analytically unramified ring is a local ring whose completion is reduced (has no nonzero nilpotent).
The following rings are analytically unramified:
pseudo-geometric reduced ring.
excellent reduced ring.
showed that every local ring of an algebraic variety is analytically unramified.
gave an example of an analytically ramified reduced local ring. Krull showed that every 1-dimensional normal Noetherian local ring is analytically unramified; more precisely he showed that a 1-dimensional normal Noetherian local domain is analytically unramified if and only if its integral closure is a finite module. This prompted to ask whether a local Noetherian domain such that its integral closure is a finite module is always analytically unramified. However gave an example of a 2-dimensional normal analytically ramified Noetherian local ring. Nagata also showed that a slightly stronger version of Zariski's question is correct: if the normalization of every finite extension of a given Noetherian local ring R is a finite module, then R is analytically unramified.
There are two classical theorems of that characterize analytically unramified rings. The first says that a Noetherian local ring (R, m) is analytically unramified if and only if there are a m-primary ideal J and a sequence such that , where the bar means the integral closure of an ideal. The second says that a Noetherian local domain is analytically unramified if and only if, for every finitely-generated R-algebra S lying between R and the field of fractions K of R, the integral closure of S in K is a finitely generated module over S. The second follows from the first.
Nagata's example
Let K0 be a perfect field of characteristic 2, such as F2.
Let K be K0({un, vn : n ≥ 0}), where the un and vn are indeterminates.
Let T be the subring of the formal power series ring K generated by K and K2 and the element Σ(unxn+ vnyn). Nagata proves that T is a normal local noetherian domain whose completion has nonzero nilpotent elements, so T is analytically ramified.
References
Commutative algebra | Analytically unramified ring | [
"Mathematics"
] | 490 | [
"Fields of abstract algebra",
"Commutative algebra"
] |
39,953,225 | https://en.wikipedia.org/wiki/C4H7Cl | {{DISPLAYTITLE:C4H7Cl}}
The molecular formula C4H7Cl (molar mass: 90.55 g/mol, exact mass: 90.0236 u) may refer to:
Crotyl chloride
Methallyl chloride
Molecular formulas | C4H7Cl | [
"Physics",
"Chemistry"
] | 59 | [
"Molecules",
"Set index articles on molecular formulas",
"Isomerism",
"Molecular formulas",
"Matter"
] |
39,953,261 | https://en.wikipedia.org/wiki/C23H38O2 | {{DISPLAYTITLE:C23H38O2}}
The molecular formula C23H38O2 (molar mass: 346.55 g/mol) may refer to:
(C9)-CP 47,497
O-1871
Rosterolone, or 1α-methyl-17α-propyl-5α-androstan-17β-ol-3-one
Molecular formulas | C23H38O2 | [
"Physics",
"Chemistry"
] | 89 | [
"Molecules",
"Set index articles on molecular formulas",
"Isomerism",
"Molecular formulas",
"Matter"
] |
39,953,304 | https://en.wikipedia.org/wiki/C19H25NO3 | {{DISPLAYTITLE:C19H25NO3}}
The molecular formula C19H25NO3 (molar mass: 315.41 g/mol, exact mass: 315.1834 u) may refer to:
Dopamantine
25D-NBOMe, or NBOMe-2C-D
Mitiglinide
Molecular formulas | C19H25NO3 | [
"Physics",
"Chemistry"
] | 76 | [
"Molecules",
"Set index articles on molecular formulas",
"Isomerism",
"Molecular formulas",
"Matter"
] |
39,953,452 | https://en.wikipedia.org/wiki/Thiolate-protected%20gold%20cluster | Thiolate-protected gold clusters are a type of ligand-protected metal cluster, synthesized from gold ions and thin layer compounds that play a special role in cluster physics because of their unique stability and electronic properties. They are considered to be stable compounds.
These clusters can range in size up to hundreds of gold atoms, above which they are classified as passivated gold nanoparticles.
Synthesis
Wet chemical synthesis
The wet chemical synthesis of thiolate-protected gold clusters is achieved by the reduction of gold(III) salt solutions, using a mild reducing agent in the presence of thiol compounds. This method starts with gold ions and synthesizes larger particles from them, therefore this type of synthesis can be regarded as a "bottom-up approach" in nanotechnology to the synthesis of nanoparticles.
The reduction process depends on the equilibrium between different oxidation states of the gold and the oxidized or reduced forms of the reducing agent, or thiols. Gold(I)-thiolate polymers have been identified as important in the initial steps of the reaction. Several synthesis recipes exist that are similar to the Brust synthesis of colloidal gold, however the mechanism is not yet fully understood. The synthesis produces a mixture of dissolved, thiolate-protected gold clusters of different sizes. These particles can then be separated by gel electrophoresis (PAGE). If the synthesis is performed in a kinetically controlled manner, particularly stable representatives can be obtained with particles of uniform size (monodispersely), avoiding further separation steps.
Template-mediated synthesis
Rather than starting from "naked" gold ions in solution, template reactions can be used for directed synthesis of clusters. The high affinity of the gold ions to electronegative and (partially) charged atoms of functional groups yields potential seeds for cluster formation. The interface between the metal and the template can act as a stabilizer and steer the final size of the cluster. Some potential templates are dendrimers, oligonucleotides, proteins, polyelectrolytes and polymers.
Etching synthesis
Top-down synthesis of the clusters can be achieved by the "etching" of larger metallic nanoparticles with redox-active, thiol-containing biomolecules. In this process, gold atoms on the nanoparticles' surface react with the thiol, dissolving as gold-thiolate complexes until the dissolution reaction stops; this leaves behind a residual species of thiolate-protected gold clusters that is particularly stable. This type of synthesis is also possible using other non thiol-based ligands.
Properties
Electronic and optical properties
The electronic structure of the thiolate-protected gold clusters is characterized by strongly pronounced quantum effects. These result in discrete electronic states, and a nonzero HOMO/LUMO gap. This existence of discrete electronic states was first indicated by the discrepancy between their optical absorption and the predictions of classical Mie scattering. The discrete optical transitions and occurrence of photoluminescence in these species are areas where they behave like molecular, rather than metallic, substances. This molecular optical behavior sharply distinguishes thiolate-protected clusters from gold nanoparticles, whose optical characteristics are driven by Plasmon resonance. Some of thiolate-protected clusters' properties can be described using a model in which the clusters are treated like "superatoms". According to this model they exhibit atomic-like electronic states, that are labeled S, P, D, F according to their respective angular momentum on the atomic level. Those clusters that have a "closed superatomic shell" configuration have indeed been identified as the most stable ones. This electronic shell closure and the resulting gain in stability is responsible for the discrete distribution of a few stable cluster sizes (magic numbers) observed in their synthesis, rather than a quasi-continuous distribution of sizes.
Magic numbers
Magic numbers are connected with the number of metal atoms in those thiolate-protected clusters which display an outstanding stability. Such clusters can be synthesized monodispersely and are end products of the etching procedure after an addition of excess thiols does not lead to further metal dissolution. Some important clusters with magic numbers are (SG:Glutathione): Au10(SG)10, Au15(SG)13, Au18(SG)14, Au22(SG)16, Au22(SG)17, Au25(SG)18, Au29(SG)20, Au33(SG)22, and Au39(SG)24.
Au20(SCH2Ph)16 is also well-known. It was greater than representatives Au102(p-MBA)44 with the para-mercaptobenzoice (para-mercapto-benzoic acid, p-MBA) produced ligand.
Structure prediction
Worthy of note is that in 2013, a structural prediction of the Au130 (SCH3)50 cluster, based on Density Functional Theory (DFT) was confirmed in 2015. This result represents the maturity of this field where calculations are able to guide the experimental work.
The following table features some sizes.
Composition database
Applications
In bionanotechnology, intrinsic properties of the clusters (for example, fluorescence) can be made available for bionanotechnological applications by linking them with biomolecules through the process of bioconjugation. The protected gold particles' stability and fluorescence makes them efficient emitters of electromagnetic radiation that can be tuned by varying the cluster size and the type of ligand used for protection. The protective shell can function (have functional groups added) in a way that selective binding (for example, as a complementary protein receptor of DNA-DNA-interaction) qualifies them for the use as biosensors.
References
Cluster chemistry | Thiolate-protected gold cluster | [
"Chemistry"
] | 1,189 | [
"Cluster chemistry",
"Organometallic chemistry"
] |
39,954,078 | https://en.wikipedia.org/wiki/Padma%20Sundar%20Malla | Padma Sundar Malla (1890–1974) () was Nepal's first electrical engineer and the first Nepalese to visit the United States. He pioneered the generation of electricity in Nepal which provided power to the country's emerging industrial sector.
Early life
Padma Sundar was born at Khauma Tol, Bhaktapur, the third among four brothers. His eldest brother was renowned educationist and author Jagat Sundar Malla. The family moved to Asan in Kathmandu so they could study at Durbar High School. Padma Sundar was inspired to go to Japan for higher studies after meeting with Japanese Buddhist monk and traveler Ekai Kawaguchi in Kathmandu.
Japan and America
In 1916, Padma Sundar and his elder brother Jagat Sundar went to Kolkata, India and secretly sailed for Japan as the government would not have given them permission to do so. The Rana regime disapproved of the general public getting an education. In Japan, Padma Sundar enrolled at the Tokyo Institute of Technology. His brother returned after making arrangements for his study and stay.
After obtaining a Bachelor of Science degree in Tokyo, he teamed up with a few Japanese friends and set sail for America for further studies. He joined the University of Michigan and studied electrical engineering, also earning the distinction of being the first Nepalese in the US.
While a student at the University of Michigan, he joined the Reserve Officers' Training Corps (ROTC) as a cadet. In 1922, he received his degree in electrical engineering.
Electrical engineer
When Padma Sundar returned to Nepal in 1925, he was not allowed to enter Kathmandu for having travelled abroad without permission. So he moved to Kurseong in West Bengal, India. In 1933, he set up his first hydropower station known as the Faji hydroelectric project which supplied energy to Kurseong.
The Nepal government sent for Padma Sundar in 1939, and named him the chief engineer of the Morang Hydroelectric Company. He designed the power station that supplied energy to Biratnagar Jute Mill, Biratnagar. He also designed other plants in Birgunj and Dharan.
Honors
In 1941, Padma Sundar was made an associate member of the Institution of Electrical Engineers, a British professional body.
Padma Sundar moved back to Kathmandu in the 1950s where he lived the rest of his life. He has been called the "father of Nepalese hydropower" for his pioneering work.
References
1890 births
1974 deaths
People from Kathmandu
Newar people
Electrical engineers
University of Michigan College of Engineering alumni
Durbar High School alumni
20th-century Nepalese nobility | Padma Sundar Malla | [
"Engineering"
] | 525 | [
"Electrical engineering",
"Electrical engineers"
] |
39,954,585 | https://en.wikipedia.org/wiki/Ribosomal%20pause | Ribosomal pause refers to the queueing or stacking of ribosomes during translation of the nucleotide sequence of mRNA transcripts. These transcripts are decoded and converted into an amino acid sequence during protein synthesis by ribosomes. Due to the pause sites of some mRNA's, there is a disturbance caused in translation. Ribosomal pausing occurs in both eukaryotes and prokaryotes. A more severe pause is known as a ribosomal stall.
It's been known since the 1980s that different mRNAs are translated at different rates. The main reason for these differences was thought to be the concentration of varieties of rare tRNAs limiting the rate at which some transcripts could be decoded. However, with research techniques such as ribosome profiling, it was found that at certain sites there were higher concentrations of ribosomes than average, and these pause sites were tested with specific codons. No link was found between the occupancy of specific codons and amount of their tRNAs. Thus, the early findings about rare tRNAs causing pause sites don't seem plausible.
Two techniques can localize the ribosomal pause site in vivo; a micrococcal nuclease protection assay and isolation of polysomal transcript. Isolation of polysomal transcripts occurs by centrifuging tissue extracts through a sucrose cushion with translation elongation inhibitors, for example cycloheximide.
Ribosome pausing can be detected during preprolactin synthesis on free polysomes, when the ribosome is paused the other ribosomes are tightly stacked together. When the ribosome pauses, during translation, the fragments that started to translate before the pause took place are overrepresented. However, along with the mRNA if the ribosome pauses then specific bands will be improved in the trailing edge of the ribosome.
Some of the elongation inhibitors, such as: cycloheximide (in eukaryotes) or chloramphenicol, cause the ribosomes to pause and to accumulate in the start codons. Elongation Factor P regulates the ribosomal pause at polyproline in bacteria, and when there is no EFP the density of ribosomes decreases from the polyproline motifs. If there are multiple ribosome pauses, then the EFP won't resolve it.
Resolution and effects on gene expression
Some forms of ribosomal pause are reversible without needing to discard the translated peptide and mRNA. This sort, usually described as a slowdown, is usually caused by polyproline stretches (resolved by EFP or eIF5A) and uncharged tRNA. Slowdowns are important for the cell to control how much protein is produced; it also aids co-translational folding of the nascent polypeptide on the ribosome, and delays protein translation while its encoding mRNA; this can trigger ribosomal frameshifting.
More severe "stalls" can be caused an actual lack of tRNA or by the mRNA terminating without a stop codon. In this case, ribosomal quality control (RQC) performs crisis rescue by translational abandonment. This releases the ribosome from the mRNA. The incomplete polypeptide is targeted for destruction; in eukaryotes, mRNA no-go decay is also triggered.
It is difficult for RQC machinery to differentiate between a slowdown and a stall. It is possible for a mRNA sequence that normally produces a protein slowly to produce nothing instead due to intervention by RQC under different conditions.
Rescue mechanisms
In bacteria, three rescue mechanisms are known.
The main, universal system involves transfer-messenger RNA (tmRNA) and SmpB. The tRNA first binds to the ribosome like a tRNA, then with SmpB's help shifts into the mRNA position to translate a short peptide ending on a normal stop codon.
Alternative ribosome-rescue factor A (ArfA) is an alternative system in E. coli. It recruits RF2.
Alternative ribosome-rescue factor B (ArfB) is another alternative from E. coli. It works like a GGQ-release factor itself, releasing the peptide from tRNA. At the same time, it fits into the mRNA tunnel to remove the mRNA.
In eukaryotes, the main mechanism involves PELO:HBS1L.
Advantage of the ribosomal pause
When the ribosome movement on the mRNA is not linear, the ribosome gets paused at different regions without a precise reason. The ribosome pause position will help to identify the mRNA sequence features, structure, and the transacting factor that modulates this process. The advantage of ribosomal pause sites that are located at protein domain boundaries are aiding the folding of a protein. There are times when the ribosomal pause does not cause an advantage and it needs to be restricted. In translation, elF5A inhibits ribosomal pausing for translation to function better. Ribosomal pausing can cause more non-canonical start codons without elF5A in eukaryotic cells. When there is a lack of elF5A in the eukaryotic cell, it can cause an increase in ribosomal pausing. The ribosomal pausing process can also be used by amino acids to control translation.
The location of the ribosome pause event in vitro
It is known that ribosomes pause at distinct sites, but the reasons for these pauses are mostly unknown. Also, the ribosome pauses if the pseudoknot is disrupted. 10% of the ribosome pauses at the pseudoknot and 4% of the ribosomes are terminated. Before the ribosome is obstructed it passes the pseudoknot. An assay was put together by a group from the University of California in an effort to show a model of mRNA. The translation was monitored in two in vitro systems. It was found that translating ribosomes aren't uniformly distributed along an mRNA. Protein folding in vivo is also important and is related to protein synthesis. For finding the location of the ribosomal pause in vivo, the methods that have been used to find the ribosomal pause in vitro can be changed to find these specific locations in vivo.
Ribosome profiling
Ribosome profiling is a method that can reveal pausing sites through sequencing the ribosome protected fragments (RPFs or footprints) to map ribosome occupancy on the mRNA. Ribosome profiling has the ability to reveal the ribosome pause sites in the whole transcriptome. When the kinetics layer is added, it discloses the time of the pause, and the translation takes place. Ribosome profiling is however still in early stages and has biases that need to be explored further. Ribosome profiling allows for translation to be measured more accurately and precisely. During this process, translation needs to be stopped in order for ribosome profiling to be performed. This may cause a problem with ribosome profiling because the methods that are used to stop translation in an experiment can impact the outcome, which causes incorrect results. Ribosome profiling is useful for getting specific information on translation and the process of protein synthesis.
See also
Translational frameshift
HIV Ribosomal frameshift signal
Coronavirus frameshifting stimulation element
Ribosomal frameshift
References
External links
Pseudobase
Recode
RNA
Gene expression
Cis-regulatory RNA elements
Molecular genetics | Ribosomal pause | [
"Chemistry",
"Biology"
] | 1,531 | [
"Gene expression",
"Molecular genetics",
"Cellular processes",
"Molecular biology",
"Biochemistry"
] |
39,955,052 | https://en.wikipedia.org/wiki/Rakuten%20TV | Rakuten TV is a video-on-demand (VOD) and free ad-supported streaming television (FAST) platform, providing movies and TV series for subscription, rental, and purchase as well as FAST channels with a mix of local and global content. Since 2019, the platform has provided users access to different content via TVOD, AVOD, SVOD, and FAST. It is owned by the Japanese company, Rakuten.
Rakuten TV's VOD catalogue includes content from studios around the world, including Warner Bros., Disney, and Sony Pictures, local distributors, and independent labels producing both locally and globally oriented content. Similarly, Rakuten TV's distribution of FAST channels includes both its own Rakuten curated channels as well as FAST channels and TV channels operated and curated by its partners around the world. Rakuten TV's content can be streamed from most devices, offering a similar service to Netflix and other streaming services.
The company is headquartered in Tokyo and Barcelona and currently operates in Japan as well as several countries around Europe; Aaland Islands, Albania, Austria, Belgium, Bosnia and Herzegovina, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Faroe Islands, Finland, France, Germany, Greece, Greenland, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Macedonia, Malta, Montenegro, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, United Kingdom, and Ukraine.
In Japan, the video streaming service Rakuten SHOWTIME changed its name to Rakuten TV on July 1, 2017 and has been operating under the new name since then.
Rakuten also operates another global video-on-demand (VOD) streaming service called Rakuten Viki which is headquartered in San Mateo, California with additional offices in Tokyo, Japan, Seoul, South Korea, and Singapore. Rakuten Viki focuses on distributing content from parts of Asia to the rest of the world. This includes drama, variety shows, and animation from Japan, Korea, Mainland China, Taiwan, and Thailand.
History
In 2010, the service was launched in Spain under the name Wuaki.tv, and later expanded to Andorra. By 2013, it had entered the markets in Britain, as well as Italy, France, and Germany later that same year.
In June 2012, e-commerce company Rakuten acquired the company, previously known as Wuaki.tv. In July 2017, Wuaki.tv changed its name to Rakuten TV. Rakuten took over the user base from TalkTalk TV Store (previously Blinkbox) including migration of user purchased titles, in June 2018.
Rakuten Sports
On 11 June 2019, Rakuten announced the launch of Rakuten Sports, a new live streaming and video on demand (VOD) sports entertainment platform to expand and deliver sports content to several countries around the world, after eleven countries across Europe.
In November 2019, Rakuten Sports provides the subscription streaming coverage of Davis Cup for two seasons 2019 and 2020, also as the part of main sponsorship, starting from the 2019 finals.
References
Video on demand services
Video rental services
Internet properties established in 2010
Rakuten
Companies based in Barcelona
2010 establishments in Spain
2012 mergers and acquisitions
Internet technology companies of Spain
Streaming media systems
Subscription video on demand services
TvOS software | Rakuten TV | [
"Technology"
] | 688 | [
"Streaming media systems",
"Telecommunications systems",
"Computer systems"
] |
39,955,238 | https://en.wikipedia.org/wiki/Roma%20wall | A Roma wall or Gypsy wall is a wall built by local authorities in the Czech Republic, Romania and Slovakia to segregate the Roma minority from the rest of the population. Such practices have been criticised by both human rights organizations and the European Union, who see it as a case of racial segregation.
Czech Republic
Ústí nad Labem
A 2-metre high, 65-metre long wall along Matiční street was built in the Czech town of Ústí nad Labem in 1999 following complaints of the locals that the Roma were "noisy and unhygienic". The local authorities argued that it's a "noise barrier" that will also keep the Roma children from running into the street and that it's part of an "urban renewal programme".
Following opposition from the European Union (Commissioner Guenter Verheugen called it "a violation of human rights"), the Czech Republic promised that it would be torn down, and it was demolished on 24 November 1999. The government provided the local authorities money for social welfare programmes, but much of the money was used for buying the houses of the non-Roma residents, thus creating a local Roma-only "ghetto".
In April 2000, the Constitutional Court of the Czech Republic ruled that the MPs exceeded their legal powers when they ordered the demolition of the wall, as this was a matter of local self-government.
Romania
Baia Mare
In Baia Mare, Romania, the local administration built a wall between the road Strada Horea and an area of social housing that houses 1000 Roma people into one-room apartments, some without water or electricity. According to the mayor, this wall was designed to "prevent traffic accidents", while pro-democracy organizations say it amounts to "institutionalized racism".
In 2011, the national anti-discrimination council fined mayor Cătălin Cherecheș for the building of the wall and ordered it to be pulled down.
The wall nevertheless proved popular with the majority population and the mayor was overwhelmingly re-elected in 2012.
Slovakia
Ostrovany
In Ostrovany, Slovakia, a 150-metre long wall was built by the local government separating the Roma from the rest of the population. According to the mayor, the goal was to "stop vandalism and theft". Slovaks accuse the Roma of stealing their fruit, vegetables and metal fence posts. Unlike in other cases, in Ostrovany, the Roma form the majority of the population (1200 of the 1786 residents), making it even more unjust, according to critics, who argue that separating people is not a solution to social problems.
Košice
A wall was built in the summer of 2013 in the town of Zapad district of Košice. Androulla Vassiliou, the European Commissioner for Education, Culture, Multilingualism and Youth complained about the wall arguing that it "violates the EU's stand against racism" by segregating the Roma people and it is at odds with the concept of European Capital of Culture, which the town bears this year.
The mayor of Košice, Richard Raši, called the wall illegally built without the necessary permits and pledged its demolition.
Other walls
In 2013, there were 14 Roma walls in Slovakia, of which 8 in the Košice and Prešov regions, have the highest Roma populations. The local authorities decide for building such walls and they usually state a different reason than the Roma people.
References
External links
The wall in Baia Mare in Google Street View
Antiziganism in the Czech Republic
Antiziganism in Romania
Antiziganism in Slovakia
Separation barriers
Fences
Racial segregation
Romani in Europe
Romani-related controversies | Roma wall | [
"Engineering"
] | 744 | [
"Separation barriers"
] |
39,956,266 | https://en.wikipedia.org/wiki/Branches%20of%20botany | Botany is a natural science concerned with the study of plants. The main branches of botany (also referred to as "plant science") are commonly divided into three groups: core topics, concerned with the study of the fundamental natural phenomena and processes of plant life, the classification and description of plant diversity; applied topics which study the ways in which plants may be used for economic benefit in horticulture, agriculture and forestry; and organismic topics which focus on plant groups such as algae, mosses or flowering plants.
Core topics
Cytology – cell structure
Epigenetics – Control of gene expression
Paleobotany – Study of fossil plants and plant evolution
Palynology – Pollen and spores
Plant biochemistry – Chemical processes of primary and secondary metabolism
Phenology – the timing of germination, flowering and fruiting
Phytochemistry – Plant secondary chemistry and chemical processes
Phytogeography – Plant Biogeography, the study of plant distributions
Phytosociology – Plant communities and interactions
Plant anatomy – Structure of plant cells and tissues
Plant ecology – Role and function of plants in the environment
Plant evolutionary developmental biology – Plant development from an evolutionary perspective
Plant genetics – Genetic inheritance in plants
Plant morphology – Structure of plants
Plant physiology – Life functions of plants
Plant reproduction – Processes of plant reproduction
Plant systematics – Classification and naming of plants
Plant taxonomy – Classification and naming of plants
Applied topics
Agronomy – Application of plant science to crop production
Arboriculture – Culture and propagation of trees
Astrobotany - The study of plants in space
Biotechnology – Use of plants to synthesize products
Dendrology – Study of woody plants, shrubs, trees and lianas
Economic botany – Study of plants of economic use or value
Ethnobotany – Plants and people. Use and selection of plants by humans
Forestry – Forest management and related studies
Horticulture – cultivation of garden plants
Marine botany – Study of aquatic plants and algae that live in seawater
Micropropagation – rapid propagation of plants using cell and tissue culture
Pharming (genetics) – Genetic engineering of plants to produce pharmaceuticals
Plant breeding – Breeding of plants with desirable genetic characters
Plant pathology (Phytopathology) – Plant diseases
Plant propagation – propagation of plants from seed, bulbs, tubers, cuttings and grafting
Pomology – Fruit and nuts
Seed technology - Seed technology is the science dealing with the methods of improving physical and genetical characteristics of seed.
Organismal topics
groups of organisms - clades, grades and guilds
Agrostology, or graminology – Poaceae (grasses)
Batology – Rubus subg. Rubus (brambles)
Bryology, or muscology – mosses (sensu stricto) or mosses, liverworts, and hornworts (sensu lato)
Caricology – Carex (sedges)
Charology – Charales (stoneworts)
Citrology – Citrus
Cycadology – Cycads
Dendrology – trees
Hepaticology, or hepatology – Marchantiophyta (liverworts)
Lichenology – lichens
Mycology, mycetology, or fungology – fungi
Orchidology – Orchidaceae
Phycology, or algology – Algae
Pteridology, or filicology – ferns and their allies
Rhodology – Rosa
Sphagnology – Sphagnum
Synantherology – Asteraceae (composites)
study of chronological dating using plants
Acanthochronology – Cactaceae
Dendrochronology – wood
References | Branches of botany | [
"Biology"
] | 724 | [
"Branches of botany"
] |
39,956,275 | https://en.wikipedia.org/wiki/David%20Spence%20%28rubber%20chemistry%29 | David Spence (September 26, 1881 – September 24, 1957) was one of the pioneering rubber chemists. He helped the war effort during the Second World War by devising new ways of extracting natural rubbers from plants, and worked to improve the processing of the rubber. Over the course of his career, he worked to improve the dyeing processes for rubber products and the vulcanization of rubber, and in developing new accelerants for strengthening lower-quality natural rubber. In 1941, he became the first recipient of the Charles Goodyear Medal, awarded by the American Chemical Society.
Biography
David was the son of the Rev. Alexander Spence (Minister of the Church of Scotland) and his wife, Agnes Spence nee Barclay (who were married in Scoonie on 15 Jun 1876). He was born at 7:00 am on 26 September 1881 at The Manse at Udny, Aberdeen County, Scotland. He was "vaccinated as per certificate dated December 18th 1881".
Spence earned his PhD from the University of Jena in Germany in 1906. Three years later, he accepted a position as the research lab director at the Diamond Rubber Company in Akron, Ohio.
He stayed at Diamond Rubber after it was purchased by B.F. Goodrich in 1912. There, he succeeded in synthesizing isoprene for use in synthetic rubber. He left the company in 1914, and started the Norwalk Tire & Rubber Company, where he was vice president and manager until 1925. He retired in 1931, after which he continued to do his own rubber research.
During his career, he was responsible for developing several different processes: he developed accelerators for the vulcanization process; a process to devulcanize rubber; a system to extract natural rubber from guayule; and a process to modify the physical properties of rubber. During World War I, Spence headed the National Research Council's Rubber Division, and he was a consultant to the War Production Board during World War II. In 1941, he became the first recipient of the Charles Goodyear Medal. He died on September 24, 1957, in New York.
Scientific career
Organic accelerators
In the early years of rubber production, high quality natural rubber was obtained from the tree, Hevea braziliensis, found in the regions bordering the Amazon river. The high quality rubber exhibited desired properties, such as a high tensile strength (greater than 2800 psi) and a two-hour vulcanization time. Vulcanization is the process by which natural rubber is strengthened by cross-linking the different polymer chains, with either elemental sulfur bridges or other molecules known as accelerators. However, high quality natural rubber was expensive, with a price exceeding $1.50 per pound. Diamond Rubber experimented with various additives, such as mercury iodide and aniline, in an attempt to improve the properties of lower quality rubber. The addition of only 2.5 to 6 percent of these additives improved the tensile strength of low quality rubber from 1800 psi to 2800 psi, and shortened the vulcanization time to a 90 minutes. However, these additives were detrimental to the lifetime of the rubber. In 1912, Spence was working with George Oenslager at Diamond Rubber to discover different additives to overcome these shortcomings. Working off of Oenslager's aniline additives, Spence discovered that p-aminodimethylaniline was a far superior accelerator, requiring only 0.5 weight percent added to the vulcanization process, to vastly improve the tensile strength of the rubber. P-aminodimethylaniline was adopted as the accelerator of choice by the Diamond Rubber Company in 1912.
Development of guayule as a rubber alternative
Throughout World War II, the allied forces suffered from a shortage of latex rubber, due to Japan cutting off America's access to the Malaysian rubber plantations. Spence, along with other allied scientists, scrambled to secure another natural rubber resource. Latex derived from Parthenium argentatum, more commonly called Guayule, was an ideal candidate as a replacement rubber due to the properties of the vulcanized rubber produced from Guayule, which were similar to the rubber produced from Malaysian rubber plantations. Latex from Guayule was first prepared in 1876, via a solvent extraction of the latex using acetone, and this extraction process was used commercially by the Diamond Rubber Company up until the 1930s.
However, the acetone extraction process was too expensive to meet the large rubber demand brought on by World War II, creating a push to develop more conventional mechanical processing methods to extract the latex. A significant production challenge in the production of latex from Guayule was that both the mass of the latex extracted, and the tensile strength of latex, fell off due to the long storage time between the harvesting of the Guayule and its processing. Spence was tasked by Intercontinental Rubber to solve this challenge.
Spence patented methodologies to both improve the quality and yield of rubber produced from Guayule via conventional mechanical techniques in 1933. Upon investigation, Spence determined that the drying of the Guayule was responsible for the high variability in both the yield and quality of the latex. Spence's retting processes of handling the Guayule shrub increased both the uniformity of the yield and the quality of rubber extracted from the Guayule plant. The retting process included soaking a crushed Guayule plant in a 1% para-dimethylphenylamine solution, in order for natural occurring bacteria and enzymes to decompose unwanted plant material into water-soluble by-products, and to prevent the oxidative loss of the plant's natural rubber. These by-products could then be washed away during the milling process. The retting process improved the milling extraction process of Guayule upwards of six percent, and improved the tensile strength from 1800-2000 psi upwards of 2800 psi, a tensile strength comparable to that of the rubber trees.
Synthetic production of isoprene
Unfortunately the rubber from the Guayule plant did not satisfy the American demand for rubber. Even though President Franklin D. Roosevelt had stockpiled roughly 1 million tons of rubber, the annual U.S. consumption rate was 600 thousand tons of rubber. Therefore, additional rubber supplies were needed in order to avert a rubber shortage. This would present a serious vulnerability in the American war machine, as rubber was used to manufacture a wide variety of war materials. President Roosevelt commissioned the American rubber and petroleum industries to quickly design and implement synthetic rubber replacements, leading to rapid expansion of both these industries. To solve the rubber shortage, Spence and scientists from Goodyear, Firestone, Goodrich, and New Jersey Standard, joined together under a patent sharing agreement. The goals of the synthetic rubber project were to either synthetically produce the isoprene monomer, or combine multiple monomers to produce a suitable synthetic substitute for rubber. Spence, together with Dr. Alexander Clark, provided a method for producing synthetic isoprene, via the dehydration of 2,3 dimethylbut-1-en-3-ol and other alcohols using glacial acetic acid. Due to his involvement in the synthesis of the isoprene monomer, Spence was the first recipient of the Charles Goodyear Medal.
The development of a novel vulcanization and dyeing process for rubber products
While working at Goodyear, Spence altered the processes for vulcanization and the application of colored dyes to rubber. Traditionally, vulcanization was accomplished in air, with sulfur and other accelerators. While observing devulcanization, Spence noticed that the decomposition products were dependent on the oxygen content in the system, and that, without oxygen, the rubber failed to devulcanize. Based on these observations, Spence developed an oxygen, sulfur, and accelerator free vulcanization process by using organic oxidizers such as quinones or organic peroxides. Spence's vulcanization process required placing the latex mixture in a pH 7 buffered solution, and applying an organic oxidizer agent to the mixture under an inert atmosphere of nitrogen.
In addition to redeveloping the vulcanization process, Spence developed a method for applying dyes to raw rubber. Prior to Spence's method, the dyes were applied during the processing of the rubber. This proved too expensive and was limited by thermal decomposition of the dyes. Submerging the rubber products in an adsorbent bath of amine dye, sodium hydrate, sodium chloride, and sulfuric acid allowed for the dyes to be bound covalently to the rubber matrix. The amines in solution reacted with primary amines in the rubber matrix to form azo dyes on the rubber fibers. This methodology of dyeing rubber was found to be applicable to raw, vulcanized, and other manufactured rubber products.
References
Scottish chemists
1881 births
1957 deaths
Polymer scientists and engineers
U.S. Synthetic Rubber Program
University of Jena alumni | David Spence (rubber chemistry) | [
"Chemistry",
"Materials_science"
] | 1,824 | [
"Polymer scientists and engineers",
"Physical chemists",
"Polymer chemistry"
] |
39,956,692 | https://en.wikipedia.org/wiki/Ammonium%20hexafluorotitanate | Ammonium hexafluorotitanate is the inorganic compound with the chemical formula (NH4)2[TiF6]. A colorless salt, the compound consists of ammonium ions and the hexafluorotitanate dianion.
Synthesis
The compound is encountered in the extraction of titanium from its principal ore ilmenite: the ore is treated with excess ammonium fluoride:
After removal of iron impurities, the titanium is recovered as a hydrated titanium dioxide by treatment of the aqueous extract of the hexafluoride with ammonia:
Structure
Many salts of hexafluorotitanate have been characterized by X-ray crystallography. In the lattice [TiF6]2- octahedra interact with the ammonium cations by hydrogen bonds.
References
Fluorine compounds
Titanium(IV) compounds
Fluorometallates | Ammonium hexafluorotitanate | [
"Chemistry"
] | 182 | [
"Inorganic compounds",
"Inorganic compound stubs"
] |
39,956,828 | https://en.wikipedia.org/wiki/Delta-P | The Delta-P is an American rocket stage, developed by McDonnell Douglas and TRW, first used on November 10, 1972 as the second stage for the Delta 1000 series. It continued to serve as the second stage for subsequent Delta 2000 and Delta 3000 flights for 17 years, with its last usage on February 8, 1988. It is propelled by a single TRW TR-201 rocket engine, fueled by Aerozine 50 and dinitrogen tetroxide, which are hypergolic.
The Delta-P traces its heritage to the Apollo Lunar Module's Descent Propulsion System. The TR-201 engine is the Descent Propulsion System modified to be a fixed thrust engine. The Descent Propulsion System was first fired in flight during the Apollo 5 mission, in a low Earth orbit test on January 22, 1968.
As the supply of these surplus Apollo engines was depleted, the Douglas/Aerojet Delta-K upper stage was introduced in the Delta 3000 program. The Delta-K was then exclusively used on the second stage for the Delta 4000, Delta 5000, and subsequent Delta II.
References
Rocket stages | Delta-P | [
"Astronomy"
] | 220 | [
"Rocketry stubs",
"Astronomy stubs"
] |
39,957,824 | https://en.wikipedia.org/wiki/List%20of%20international%20databases%20on%20individual%20student%20achievement%20tests | This article contains a list of international databases on individual student achievement tests that can be used for psychometric research. In other words, this table only includes datasets containing items measuring ability and directly answered by students.
See also
List of online databases
References
Academic publishing
academic databases
Bibliographic databases and indexes
Databases | List of international databases on individual student achievement tests | [
"Technology"
] | 65 | [
"Computing-related lists",
"Internet-related lists"
] |
39,957,986 | https://en.wikipedia.org/wiki/Peter%20Schattschneider | Peter Schattschneider (born 1950 in Vienna) is an Austrian physicist and science-fiction writer, a retired professor at the Institute of Solid State Physics and a staff member of the USTEM special unit of the Vienna University of Technology. His research focuses on electron microscopy, specifically on electron energy loss spectroscopy and the inelastic interactions between electrons and matter. He is also interested in the history of physics, the science in science fiction, and the role of science in society. His group was responsible for the discovery of electron magnetic circular dichroism in 2006.
Life
Peter Schattschneider completed his diploma degree in Physics in 1973 at the Vienna University of Technology, with a thesis entitled X-ray diffusion profiles in thin layers (). In 1976 he successfully defended his PhD thesis on The determination of lattice constants of binary alloys from X-ray diffraction profiles () at the same university. From 1974 to 1977 he was also enrolled at the University of Vienna where he obtained a mag. rer. nat. degree in the college teaching of Physics and Mathematics. After working for a few years on air- and spaceborn sensors in a private engineering enterprise, he returned to his alma mater in 1980 as an assistant in the Institute for Applied and Technical Physics, where he became Assistant Professor in 1988.
In 1978 he published his first Science Fiction story () and afterwards has published other stories in Anthologies and Magazines.
From 1992 to 1993, he worked at the CNRS (Centre Nationale de la Recherche Scientifique) in Paris. Since 1995 he has been an invited professor at the École Centrale Paris. From 2000 to 2006 he was the head of the newly established University Service for Transmission Electron Microscopy at the Vienna University of Technology. Although he officially retired in 2015, he is still an active researcher. In October 2016 he received a decoration from the Vienna University of Technology for "his research on electron energy loss spectroscopy and the development of the theoretical foundations in the fields of ELNES, EMCD and most recently electron vortex beams".
Awards
1981: Theodor Körner Prize for his work on EELS.
1992: Kurd-Laßwitz-Preis for the short story Pflegeleicht
1995: Kurd-Laßwitz-Preis for the short story Brief aus dem Jenseits
Works
As author
Novels
Singularitäten. Ein Episodenroman im Umfeld schwarzer Löcher. Suhrkamp, Frankfurt/M. 1984, .
Hell Fever – Höllische Spiele. Science-Fiction novel. Hinstorff Verlag, Rostock. 2019, ISBN 978-3-356-02276-6.
The Exodus Incident. Science-Fiction novel. Springer. 2021, ISBN 978-3-030-70018-8
Short stories
Zeitstopp. Science-Fiction-Geschichten (; vol. 76). Suhrkamp, Frankfurt/M. 1982, .
Selbstgespräch mit Protoplasma. Erzählungen aus der Zukunft. Verlag im Waldgut, Frauenfeld 2009, (with an epilogue by Franz Rottensteiner).
Non-fiction books
Fundamentals of inelastic electron scattering. Springer, Wien 1986, .
As editor
Science Fiction - Werkzeug oder Sensor einer technisierten Welt? Vortragsreihe. EDFC, Passau 1995 (with Karlheinz Steinmüller)
Linear and chiral dichroism in the electron microscope. Pan Stanford, Singapore 2012,
Literature
Franz Rottensteiner: Peter Schattschneider. Das Spiel mit der Wirklichkeit, in: Franz Rottensteiner: Im Labor der Visionen. Anmerkungen zur phantastischen Literatur. 19 Aufsätze und Vorträge aus den Jahren 2000–2012, Verlag Dieter van Reeken, Lüneburg 2013, , p. 189–198.
Günter Zettl: Interview mit Peter Schattschneider, in: Science Fiction Times, 26th year, 1984, issue 9, p. 5–8.
References
External links
Peter Schattschneider webpage at USTEM
Microscopists
Living people
Theodor Körner Prize recipients
1950 births
20th-century Austrian scientists
Austrian physicists
Scientists from Vienna
TU Wien alumni
Austrian male writers
Austrian science fiction writers
Austrian male short story writers | Peter Schattschneider | [
"Chemistry"
] | 901 | [
"Microscopists",
"Microscopy"
] |
39,958,179 | https://en.wikipedia.org/wiki/NEKAAL | NEKAAL is the Northeast Kansas Amateur Astronomers' League, a non-profit educational and scientific organization founded 1978 and based in Topeka, Kansas. NEKAAL and its members specialize in educational outreach to surrounding counties, and in discovering and refining orbits of solar system objects including comets and asteroids.
NEKAAL is a member of the International Dark-Sky Association and the Night Sky Network, and operates the Farpoint Observatory southwest of Topeka.
References
External links
NEKAAL website
NEKAAL Observer (newsletter)
Non-profit organizations based in Kansas | NEKAAL | [
"Astronomy"
] | 113 | [
"Astronomy stubs"
] |
39,958,236 | https://en.wikipedia.org/wiki/Superspreading%20event | A superspreading event (SSEV) is an event in which an infectious disease is spread much more than usual, while an unusually contagious organism infected with a disease is known as a superspreader. In the context of a human-borne illness, a superspreader is an individual who is more likely to infect others, compared with a typical infected person. Such superspreaders are of particular concern in epidemiology.
Some cases of superspreading conform to the 80/20 rule, where approximately 20% of infected individuals are responsible for 80% of transmissions, although superspreading can still be said to occur when superspreaders account for a higher or lower percentage of transmissions. In epidemics with such superspreader events, the majority of individuals infect relatively few secondary contacts. The degree to which superspreading contributes to an epidemic is often quantified by the t20 metric, which denotes the proportion of infections attributable to the most infectious 20% of the population.
SSEVs are shaped by multiple factors including a decline in herd immunity, nosocomial infections, virulence, viral load, misdiagnosis, airflow dynamics, immune suppression, and co-infection with another pathogen.
Definition
Although loose definitions of superspreader events exist, some effort has been made at defining what qualifies as a superspreader event (SSEV). Lloyd-Smith et al. (2005) define a protocol to identify a superspreader event as follows:
estimate the effective reproductive number, R, for the disease and population in question;
construct a Poisson distribution with mean R, representing the expected range of Z due to stochasticity without individual variation;
define an SSEV as any infected person who infects more than Z(n) others, where Z(n) is the nth percentile of the Poisson(R) distribution.
This protocol defines a 99th-percentile SSEV as a case which causes more infections than would occur in 99% of infectious histories in a homogeneous population.
During the SARS-CoV-1 2002–2004 SARS outbreak from China, epidemiologists defined a superspreader as an individual with at least eight transmissions of the disease.
Superspreaders may or may not show any symptoms of the disease.
SSEVs can further be classified into 'societal' and 'isolated' events. Funerals have been known to epidemiology as common superspreader events. In particular where funeral rites involve contact with the decedent, funerary transmission may occur. The International Red Cross proposed the practices now known as "safe and dignified burials" during the Western African Ebola virus epidemic to reduce funerary transmission.
In April 2020 Jonathan Kay reported in relation to the COVID-19 pandemic:
Factors in transmission
Superspreaders have been identified who excrete a higher than normal number of pathogens during the time they are infectious. This causes their contacts to be exposed to higher viral/bacterial loads than would be seen in the contacts of non-superspreaders with the same duration of exposure.
Basic reproductive number
The basic reproduction number R0 is the average number of secondary infections caused by a typical infective person in a totally susceptible population. The basic reproductive number is found by multiplying the average number of contacts by the average probability that a susceptible individual will become infected, which is called the shedding potential.
Individual reproductive number
The individual reproductive number represents the number of secondary infections caused by a specific individual during the time that individual is infectious. Some individuals have significantly higher than average individual reproductive numbers and are known as superspreaders. Through contact tracing, epidemiologists have identified superspreaders in measles, tuberculosis, rubella, monkeypox, smallpox, Ebola hemorrhagic fever and SARS.
Co-infections with other pathogens
Studies have shown that men with HIV who are co-infected with at least one other sexually transmitted disease, such as gonorrhea, hepatitis C, and herpes simplex 2 virus, have a higher HIV shedding rate than men without co-infection. This shedding rate was calculated in men with similar HIV viral loads. Once treatment for the co-infection has been completed, the HIV shedding rate returns to levels comparable to men without co-infection.
Lack of herd immunity
Herd immunity, or herd effect, refers to the indirect protection that immunized community members provide to non-immunized members in preventing the spread of contagious disease. The greater the number of immunized individuals, the less likely an outbreak can occur because there are fewer susceptible contacts. In epidemiology, herd immunity is known as a dependent happening because it influences transmission over time. As a pathogen that confers immunity to the survivors moves through a susceptible population, the number of susceptible contacts declines. Even if susceptible individuals remain, their contacts are likely to be immunized, preventing any further spread of the infection. The proportion of immune individuals in a population above which a disease may no longer persist is the herd immunity threshold. Its value varies with the virulence of the disease, the efficacy of the vaccine, and the contact parameter for the population. That is not to say that an outbreak can't occur, but it will be limited.
Superspreaders during outbreaks or pandemics
COVID-19 pandemic: 2020–present
Several factors are identified as contributing to superspreading events with COVID-19: closed spaces with poor ventilation, crowds, and close contact settings ("three Cs").
The South Korean spread of confirmed cases of SARS-CoV-2 infection jumped suddenly starting on 19–20 February 2020. On 19 February, the number of confirmed cases increased by 20. On 20 February, 58 or 70 new cases were confirmed, giving a total of 104 confirmed cases, according to the Centers for Disease Control and Prevention Korea (KCDC). According to Reuters, KCDC attributed the sudden jump to 70 cases linked to "Patient 31", who had participated in a gathering in Daegu at the Shincheonji Church of Jesus the Temple of the Tabernacle of the Testimony. On 20 February, the streets of Daegu were empty in reaction to the Shincheonji outbreak. A resident described the reaction, stating "It's like someone dropped a bomb in the middle of the city. It looks like a zombie apocalypse." On 21 February, the first death was reported. According to the mayor of Daegu, the number of suspected cases as of 21 February is 544 among 4,400 examined followers of the church. Later in the outbreak, in May, a 29-year-old man visited several Seoul nightclubs in one night and resulted in accumulated infections of at least 79 other people.
A two-day leadership conference for the American biotechnology company Biogen was held at the Mariott Long Wharf Hotel in Boston, Massachusetts, from 26 to 28 February 2020. 99 of the 175 executives in attendance later tested positive for COVID-19, and the hotel was shut down days later. A genetic analysis study published later the same year estimated the spread at the conference eventually resulted in 1.9% of U.S. coronavirus cases, or as many as 300,000 people. The event was the subject of a New York Times article, and substantial criticism was leveled at Biogen for its role in the incident.
Between 27 February and 1 March, a Tablighi Jamaat event at Masjid Jamek, Seri Petaling in Kuala Lumpur, Malaysia attended by approximately 16,000 people resulted in a major outbreak across the country. By May 16, 3,348 COVID-19 cases - 48% of Malaysia's total at the time - were linked to the event, and with approximately 10% of attendees visiting from overseas, the event resulted in the virus spreading across Southeast Asia. Cases in Cambodia, Indonesia, Vietnam, Brunei, the Philippines and Thailand were traced back to the mosque gathering.
In New York, a lawyer contracted the illness then spread it to at least twenty other individuals in his community in New Rochelle, creating a cluster of cases that quickly passed 100, accounting for more than half of SARS-CoV2 coronavirus cases in the state during early March 2020. For comparison, the basic reproduction number of the virus, which is the average number of additional people that a single case will infect without any preventative measures, is between 1.4 and 3.9.
On March 6, preacher Baldev Singh returned to India after being infected while traveling in Italy and Germany. He subsequently died, becoming the first coronavirus fatality in the State of Punjab. Testing revealed that he'd infected 26 locals, including 19 relatives, while tracing discovered that he'd had direct contact with more than 550 people. Fearing an outbreak, India's government instituted a local quarantine on 27 March 2020, affecting 40,000 residents from 20 villages. Initial reports claimed that Baldev Singh had ignored self-quarantine orders, and police collaborated with singer Sidhu Moose Wala to release a rap music video blaming the dead man for bringing the virus to Punjab. But Baldev Singh's fellow travelers insisted that no such order had been given, leading to accusations that local authorities had scapegoated him to avoid scrutiny of their own failures.
A Tablighi Jamaat religious congregation that took place in Delhi's Nizamuddin Markaz Mosque in early March 2020 was a coronavirus super-spreader event, with more than 4,000 confirmed cases and at least 27 deaths linked to the event reported across the country. Over 9,000 missionaries may have attended the congregation, with the majority being from various states of India, and 960 attendees from 40 foreign countries. On 18 April, 4,291 confirmed cases of COVID-19 linked to this event by the Union Health Ministry represented a third of all the confirmed cases of India. Around 40,000 people, including Tablighi Jamaat attendees and their contacts, were quarantined across the country.
On 11 May 2020, it came to light that a worker at a fish processing plant in Tema, Ghana was believed to have infected over 500 other people with COVID-19.
As of 18 July 2020, more than one thousand suspected superspreading events had been logged, for example a cluster of 187 people who were infected after eating at a Harper's Restaurant and Brew Pub in East Lansing, Michigan.
On 26 September 2020, President Donald Trump announced his Supreme Court Justice nominee, Amy Coney Barrett. The announcement took place at the White House Rose Garden, where around 30 people attentively watched. The outbreak event has since been dubbed a "superspreader" event. Less than a week after the event, Trump himself was diagnosed with SARS-CoV-2, as well as others who attended the Rose Garden event. By October 7, the Federal Emergency Management Agency memo revealed that 34 White House staff members, housekeepers, and other contacts had contracted the virus.
Public health experts have said that the 2021 United States Capitol attack was a potential COVID-19 superspreading event. Few members of the crowd attacking the Capitol wore face coverings, with many coming from out of town, and few of the rioters were immediately detained and identified.
On 30 July 2021, it came to light that a Peruvian man, resident of Córdoba, Argentina, brought the Delta variant of COVID-19 after travelling to Spain, but he did not quarantine himself, infecting 17 relatives and putting in isolation over 800 other people. He and other three people got arrested for disease propagation. 24 days later, the Peruvian man died of a severe pneumonia, being the first death of the Delta variant in Spain.
On 26 November 2021, Scatec ASA, a Norwegian company specializing in renewable energy systems, held a Christmas party in Oslo, Norway attended by 120 people, all of whom were fully vaccinated against COVID-19 and tested negative for COVID-19 prior to the party being held. One person who attended the party had recently returned from South Africa, the epicenter of the SARS-CoV-2 Omicron variant outbreak and a country where the company has a solar panel project. It was later found that the attendee from South Africa had been infected with the Omicron variant. More than half of the party's attendees have since tested positive for COVID-19 and of those attendees, at least 13 of them were confirmed to have the variant.
On 3 April 2022, the Gridiron Dinner in Washington D.C. led to at least 67 people testing positive for COVID-19, including three members of the Cabinet of Joe Biden: Merrick Garland, Gina Raimondo, and Tom Vilsack.
SARS outbreak: 2003
The first cases of SARS occurred in mid-November 2002 in the Guangdong Province of China. This was followed by an outbreak in Hong Kong in February 2003. A Guangdong Province doctor, Liu Jianlun, who had treated SARS cases there, had contracted the virus and was symptomatic. Despite his symptoms, he traveled to Hong Kong to attend a family wedding. He stayed on the ninth floor of the Metropole Hotel in Kowloon, infecting 16 other hotel guests also staying on that floor. The guests then traveled to Canada, Singapore, Taiwan, and Vietnam, spreading SARS to those locations and transmitting what became a global epidemic.
In another case during this same outbreak, a 54-year-old male was admitted to a hospital with coronary heart disease, chronic kidney failure and type II diabetes mellitus. He had been in contact with a patient known to have SARS. Shortly after his admission he developed fever, cough, myalgia and sore throat. The admitting physician suspected SARS. The patient was transferred to another hospital for treatment of his coronary artery disease. While there, his SARS symptoms became more pronounced. Later, it was discovered he had transmitted SARS to 33 other patients in just two days. He was transferred back to the original hospital where he died of SARS.
In his post-mortem reflection, Low remained puzzled as to the reason for this phenomenon and speculated that "possible explanations for (the superspreaders') enhanced infectivity include the lack of early implementation of infection control precautions, higher load of SCoV, or larger amounts of respiratory secretions."
The SARS outbreak was eventually contained, but not before it caused 8,273 cases and 775 deaths. Within two weeks of the original outbreak in Guangdong Province, SARS had spread to 29 countries.
Measles outbreak: 1989
Measles is a highly contagious, air-borne virus that reappears even among vaccinated populations. In one Finnish town in 1989, an explosive school-based outbreak resulted in 51 cases, several of whom had been previously vaccinated. One child alone infected 22 others. It was noted during this outbreak that when vaccinated siblings shared a bedroom with an infected sibling, seven out of nine became infected as well.
Typhoid fever
Typhoid fever is a human-specific disease caused by the bacterium Salmonella typhi. It is highly contagious and becoming resistant to antibiotics. S. typhi is susceptible to creating asymptomatic carriers. The most famous carriers are Mary Mallon, known as Typhoid Mary, from New York City, and Mr. N. the Milker, from Folkestone, England. Both were active around the same time. Mallon infected 51 people from 1902 to 1909. Mr. N. infected more than 200 people over 14 years from 1901 to 1915. At the request of health officials, Mr. N. gave up working in food service. Mallon was at first also compliant, choosing other work – but eventually she returned to cooking and caused further outbreaks. She was involuntarily quarantined at Brothers Island in New York, where she stayed until she died in November 1938, aged 69.
It has been found that Salmonella typhi persists in infected mice macrophages that have cycled from an inflammatory state to a non-inflammatory state. The bacteria remain and reproduce without causing further symptoms in the mice, and this helps to explain why carriers are asymptomatic.
See also
Amoy Gardens 2003 SARS outbreak
Scale-free network – A model in which most people spread an infection to few people, but a few people spread infection to many
References
External links
World Health Organisation (WHO) – authoritative source of information about global health issues
Past pandemics that ravaged Europe at the BBC
Influenza pandemic phases at the US Center for Disease Control (CDC)
European Centre for Disease Prevention and Control (ECDC)
TED-Education video – How pandemics spread
Biological hazards
Epidemics
Epidemiology
Global health
Infectious diseases
Pandemics
Zoonoses | Superspreading event | [
"Environmental_science"
] | 3,500 | [
"Epidemiology",
"Environmental social science"
] |
39,960,426 | https://en.wikipedia.org/wiki/Charles%20Katz | Charles Abraham Katz (July 7, 1927 – May 9, 1974) was an American mathematician and computer scientist known for his contributions to early compiler development in the 1950s.
Katz received two degrees in mathematics, a Bachelor of Science (B.S.) at Temple University in 1950, and a Master of Science (M.S.) at the University of Pennsylvania in 1953. He then went to work at Remington Rand, in the UNIVAC division, with Grace Hopper to develop compilers for her A-0 system UNIVAC programming languages starting with A-2, followed by MATH-MATIC and FLOW-MATIC. He then went on to General Electric, Burroughs Corporation, and Xerox.
In 1958, he served as one of the original four American members of the International Federation for Information Processing (IFIP) IFIP Working Group 2.1 on Algorithmic Languages and Calculi, which specified, supports, and maintains the languages ALGOL 60 and ALGOL 68.
Katz died in Rockville, Maryland on May 9, 1974, at the age of 46.
References
1927 births
1974 deaths
American computer programmers
Temple University alumni
University of Pennsylvania alumni | Charles Katz | [
"Technology"
] | 236 | [
"Computing stubs",
"Computer specialist stubs"
] |
39,960,632 | https://en.wikipedia.org/wiki/Riccardo%20Barbieri | Riccardo Barbieri (born 1944) is an Italian theoretical physicist and a professor at the Scuola Normale Superiore di Pisa. He has written more than two hundred research papers in the field of theoretical elementary particle physics, and has been particularly influential in physics beyond the Standard Model.
Research career
Riccardo Barbieri received his undergraduate education in 1963-67 at the Scuola Normale Superiore in Pisa and at the University of Pisa. His laurea advisor was Pietro Menotti. During his professionalization classes (perfezionamento) in 1967-69 at the Scuola Normale Superiore and in later years he worked on higher-order radiative corrections in Quantum Electrodynamics with Ettore Remiddi. In the 1970s he turned to computations in Quantum Chromodynamics, collaborating in particular with Raoul Gatto and Zoltan Kunszt. In 1976 at CERN, he made the prediction, later experimentally verified, of the hadronic widths of the three charmonium P-waves.
In 1980-82, Riccardo Barbieri was a staff member at the CERN Theory Division. The Standard Model of particle physics by then well established, he started focussing on models beyond the Standard Model, in particular supersymmetry. In 1982, he formulated the first realistic model of mediation of supersymmetry breaking via supergravity.
Since 1984 and until now, Riccardo Barbieri has been the professor of theoretical physics at Pisa, first at the University of Pisa (1984–97), and then at the Scuola Normale Superiore (1998–present). Some of his most influential results in this period include:
In 1988, the quantitative formulation of the naturalness concept in supersymmetric models.
In 1990, the formulation of a reference parametrization of the quantum corrections to the electroweak precision observables.
In 1995, pointing out the significance of flavour and CP violations in supersymmetric unified theories even in the absence of any flavour or CP violation in the input for the soft-supersymmetry breaking parameters.
In 2006, the proposal of a Dark Matter model based on a second Higgs doublet without vacuum expectation value.
Mentoring
Having taught in Pisa for 30 years, Riccardo Barbieri is acclaimed for creating a numerous and flourishing school of theoretical high-energy physics. Among many of his students and postdocs who went on to become professors of theoretical physics in Italy and around the world, are Gian F. Giudice, and Michelangelo Mangano (permanent staff members at the CERN), Giovanni Ridolfi (professor at Universita' di Genova), Riccardo Rattazzi (professor at the EPFL), Francesco Vissani (INFN director of research at Laboratori Nazionali del Gran Sasso), Alessandro Strumia (professor at the University of Pisa), Andrea Romanino (professor at SISSA), Roberto Contino (professor at the Sapienza University of Rome), Paolo Creminelli (professor at the ICTP), Michele Papucci (Divisional Fellow at the Berkeley National Laboratory ), Gia Dvali (professor at the LMU Munich), Vyacheslav Rychkov (professor at the IHES), Stefania Gori (professor at UC Santa Cruz).
Famous quotes
“Elementary particle physics is the quadrant of nature whose laws can be written in a few lines with absolute precision and the greatest empirical adequacy.”
Awards and honours
Prof. Barbieri was awarded the "Ordine del Cherubino" from the University of Pisa in 1997, the Humboldt Prize and, more recently, the Physics Prize of "Accademia Nazionale dei Lincei" in 2017. He was also a Miller Visiting Professor at the University of California, Berkeley.
Books
Barbieri, R. (2007). Lectures on the Electroweak Interactions, Publications of the Scuola Normale Superiore, Vol. 5
References
External links
Scientific publications of Riccardo Barbieri on INSPIRE-HEP
20th-century Italian physicists
Quantum physicists
Living people
1944 births
Italian theoretical physicists
People associated with CERN
21st-century Italian physicists | Riccardo Barbieri | [
"Physics"
] | 877 | [
"Quantum physicists",
"Quantum mechanics"
] |
55,827,814 | https://en.wikipedia.org/wiki/Paint%20Research%20Association | The Paint Research Association is a research institute, formerly in Teddington, south-west London, and now in Melton Mowbray, Leicestershire. It is now known as the PRA.
History
It was established as the Research Association of British Paint, Colour and Varnish Manufacturers in 1926; in 1971 it changed its name to the Paint Research Association. Historically, the main paint manufacturer in the UK has been ICI, under the trade name of Dulux.
Its first main research institute building opened in 1936. In 2005, it moved to the Coatings Technology Centre. In 2015, it moved to Melton.
Function
It carried out research for the government and for industry. It claims to be a world authority on paint and surface coatings.
References
External links
PRA
1926 establishments in the United Kingdom
Chemical industry in the United Kingdom
Chemical research institutes
Borough of Melton
Paint and coatings industry
Research institutes established in 1926
Research institutes in Leicestershire
Research institutes in London | Paint Research Association | [
"Chemistry"
] | 195 | [
"Chemical research institutes",
"Paint and coatings industry",
"Coatings",
"Chemistry organization stubs"
] |
55,828,680 | https://en.wikipedia.org/wiki/Black%20Hole%20Initiative | The Black Hole Initiative (BHI) is an interdisciplinary center at Harvard University that includes the fields of astronomy, physics, and philosophy, and is claimed to be the first center in the world to focus on the study of black holes. Principal participants include Sheperd S. Doeleman, Peter Galison, Avi Loeb, Andrew Strominger and Shing-Tung Yau. The BHI inauguration was held on 18 April 2016 and attended by Stephen Hawking; related workshop events were held on 19 April 2016. Robbert Dijkgraaf created the mural for the BHI Inauguration.
The BHI is funded by the John Templeton Foundation and the Gordon and Betty Moore Foundation. Harvard University allocated office space for the BHI on the second floor of 20 Garden Street in Cambridge, Massachusetts. The BHI is an independent Center within the Faculty of Arts & Sciences at Harvard University.
See also
Cosmology
Galactic Center
Galaxy
General relativity
List of black holes
Outline of black holes
Timeline of black hole physics
References
External links
Official website
Official Youtube Channel
Inauguration workshop events (19 April 2017):
Astrophysics research institutes
Cosmological simulation
Physical cosmology
Black holes
Research institutes established in 2016
Harvard University research institutes
2016 establishments in Massachusetts | Black Hole Initiative | [
"Physics",
"Astronomy"
] | 250 | [
"Physical phenomena",
"Black holes",
"Applied and interdisciplinary physics",
"Physical quantities",
"Philosophy of physics",
"Astronomical sub-disciplines",
"Theoretical physics",
"Unsolved problems in physics",
"Astrophysics",
"Computational physics",
"Quantum gravity",
"Density",
"Astroph... |
55,828,944 | https://en.wikipedia.org/wiki/Bellman%27s%20lost-in-a-forest%20problem | Bellman's lost-in-a-forest problem is an unsolved minimization problem in geometry, originating in 1955 by the American applied mathematician Richard E. Bellman. The problem is often stated as follows: "A hiker is lost in a forest whose shape and dimensions are precisely known to him. What is the best path for him to follow to escape from the forest?" It is usually assumed that the hiker does not know the starting point or direction he is facing. The best path is taken to be the one that minimizes the worst-case distance to travel before reaching the edge of the forest. Other variations of the problem have been studied.
Although non-contrived real-world applications are not apparent, the problem falls into a class of geometric optimization problems, including search strategies that are of practical importance. A bigger motivation for study has been the connection to Moser's worm problem. It was included in a list of 12 problems described by the mathematician Scott W. Williams as "million buck problems" because he believed that the techniques involved in their resolution will be worth at least a million dollars to mathematics.
Approaches
A proven solution is only known for a few shapes or classes of shape, such as regular polygons and a circle. In particular, all shapes which can enclose a 60° rhombus with longer diagonal equal to the diameter have a solution of a straight line. The equilateral triangle is the only regular polygon which does not have this property, and has a solution consisting of a zig-zag line with three segments of equal length. The solution for many other shapes remains unknown. A general solution would be in the form of a geometric algorithm which takes the shape of the forest as input and returns the optimal escape path as the output.
References
Metric geometry
Discrete geometry
Unsolved problems in geometry
Recreational mathematics | Bellman's lost-in-a-forest problem | [
"Mathematics"
] | 383 | [
"Geometry problems",
"Discrete mathematics",
"Unsolved problems in mathematics",
"Recreational mathematics",
"Discrete geometry",
"Unsolved problems in geometry",
"Mathematical problems"
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55,829,848 | https://en.wikipedia.org/wiki/ASTERIA%20%28spacecraft%29 | ASTERIA (Arcsecond Space Telescope Enabling Research In Astrophysics) was a miniaturized space telescope technology demonstration and opportunistic science mission to conduct astrophysical measurements using a CubeSat. It was designed in collaboration between the Massachusetts Institute of Technology (MIT) and NASA's Jet Propulsion Laboratory. ASTERIA was the first JPL-built CubeSat to have been successfully operated in space. Originally envisioned as a project for training early career scientists and engineers, ASTERIA's technical goal was to achieve arcsecond-level line-of-sight pointing error and highly stable focal plane temperature control. These technologies are important for precision photometry, i.e., the measurement of stellar brightness over time. Precision photometry, in turn, provides a way to study stellar activity, transiting exoplanets, and other astrophysical phenomena.
ASTERIA was launched on and deployed into low Earth orbit from the International Space Station on . The primary mission lasted 90days, but the satellite continued operations for 745days through three extended missions until last successful communications were made on . The satellite decayed on . The Principal Investigator was Canadian-American astronomer and planetary scientist Sara Seager, from the Massachusetts Institute of Technology.
Overview
The Arcsecond Space Telescope Enabling Research in Astrophysics (ASTERIA) was a six-unit (6U) CubeSat space telescope deployed from the International Space Station (ISS) with the goal of testing new technologies for the detection of exoplanets using the transit method. The program was funded at JPL through the Phaeton Program for training early career employees. Its target mission lasted for 90days, after which it was extended until the loss of contact with the spacecraft.
ASTERIA's capabilities enabled precision photometry to be performed on an opportunistic basis to study stellar activity, transiting exoplanets, and other astrophysical phenomena. The technological objectives of the mission were "to achieve arcsecond-level line of sight pointing error, and highly stable focal plane temperature control for precision photometry" as a way to detect transiting exoplanets, and characterize their host stars. The pointing stability was demonstrated over 20-minute observations. Pointing repeatability would be determined over a minimum of five observations over eight or more days, with the target star being returned to the same position on the focal plane by adjusting the spacecraft orientation and focal plane position.
This mission may serve as a pathfinder for a fleet of low-cost space telescopes observing multiple targets at once to refine long-term mission goals by identifying new objects for other telescopes to observe. The miniaturization of a photometric detection system into a CubeSat could enable a constellation of multiple orbiting observatories for a continuous study of the brightest Sun-like stars which is not possible by conventional space observatories given their cost. Having one or more CubeSats pointed at a target star for extended duration could reveal long-transiting exoplanets. This mission also provided additional information in the design of future space telescopes.
Launch
ASTERIA was launched on board a SpaceX Falcon-9 rocket (mission SpaceX CRS-12) on and it was deployed to low Earth orbit from the International Space Station in . A crew member in the ISS transferred the satellite from the cargo vehicle to the Japanese Experiment Module (JEM) airlock for transfer outside the ISS.
Design
The ASTERIA concept was a follow-on to the proposed 3U CubeSat mission called ExoplanetSat that was designed in the early 2010s. The ASTERIA telescope is a 6U CubeSat measuring 10×20×30cm, and has a mass of . Power was supplied by deployable fixed solar panels and rechargeable batteries.
Commercial reaction wheels provided coarse orientation (attitude control), while fine pointing control was achieved by tracking a set of guide stars on the active pixel sensor (CMOS) and moving the piezoelectric positioning stage to compensate for residual pointing errors. The goal was to maintain the target star image to within a fraction of a detector pixel over long durations, with a pointing accuracy better than 60arcsecond, and optimally as precise as 5arcsecond over a period of 20minutes. The gain of each pixel was temperature sensitive, so the second objective of ASTERIA was to demonstrate milliKelvin-level (1mK=10K) temperature stability of the imaging detector.
ASTERIA demonstrated the ability to collect photometric data, and process photometric light curves from a CubeSat. Secondary applications included measuring stellar rotation periods, characterizing stellar activity of exoplanet hosts, and supporting ground-based radial velocity measurements with simultaneous photometry. After the success of its 90-day planned mission, ASTERIA's extended mission targeted bright stars (luminosityVmag<8) with known low-mass planets discovered by the radial velocity method, that are not yet known to transit.
Scientific payload
The telescope payload consisted of a lens and baffle assembly, a CMOS imager, and a two-axis piezoelectric positioning stage on which the focal plane was mounted. The optics section was composed of an f/1.4 85mm Zeiss lens with a 28.6-degree field of view and six elements, focusing an image 43mm in diameter onto the focal plane. The focal plane array housed two active detector areas – one larger CMOS detector that fulfilled the science function, and a smaller CMOS sensor to acted as a rapid-cadence star camera to provide orientation data to the attitude control system.
In , NASA's JPL reported that ASTERIA "has accomplished all of its primary mission objectives, demonstrating that the miniaturized technologies on board can operate in space as expected."
References
CubeSats
Space telescopes orbiting Earth
Exoplanet search projects
Jet Propulsion Laboratory
Massachusetts Institute of Technology
Satellites deployed from the International Space Station
Spacecraft decommissioned in 2019
Space probes launched in 2017
Secondary payloads
NASA satellites orbiting Earth | ASTERIA (spacecraft) | [
"Astronomy"
] | 1,237 | [
"Astronomy projects",
"Exoplanet search projects",
"Space telescopes",
"Space telescopes orbiting Earth"
] |
55,830,282 | https://en.wikipedia.org/wiki/Kepler-1652b | Kepler-1652b (also known by its Kepler Objects of Interest designation KOI-2626.01) is a super-Earth exoplanet, orbiting within the habitable zone of the red dwarf Kepler-1652 about 822 light-years away in the Cygnus constellation. Discovered by NASA's Kepler spacecraft, Kepler-1652b was first announced as a candidate in 2013, but wasn't validated until four years later in 2017. It is a potential super-Earth with 160% Earth's radius. The planet orbits well within the habitable zone of its system, the region where liquid water can exist on a planet's surface. The planet is an eyeball planet candidate.
Characteristics
Mass, radius, and temperature
Kepler-1652b, like almost all of Kepler's known exoplanets, was found with the transit method, where a planet blocks a tiny fraction of its host star's light when it passed between the star and Earth's line of sight. As a result, the only well-established parameter is its radius. Based on the size of the star and the amount of light blocked, Kepler-1652b has a radius of 1.60 , within the super-Earth range between the sizes of Earth and the ice giants Uranus and Neptune. Usually, the transition between rocky Super-Earths and gaseous Mini-Neptunes is expected to be at 1.6 , which would suggest that Kepler-1652b may be a small ice giant or ocean planet. Kepler-1652b has an equilibrium temperature of , similar to Earth's at .
Orbit
Kepler-1652b has an orbital period of 38.1 days, over 9 times shorter than Earth's year of 365 days. It has a semi-major axis, or average orbital radius, of 0.1654 AU, also much lower than Earth's. Despite its close proximity to the star, Kepler-1652b is still temperate, due to how small Kepler-1652 is compared to the Sun. The planet's eccentricity is believed to be near or at 0.
Host star
Kepler-1652b orbits the red dwarf star Kepler-1652, also designated KOI-2626. It is 0.404 times the mass and 0.382 times the radius of the Sun, with a temperature of 3638 K and an age of 3.2 billion years. For comparison, the Sun has a temperature of 5778 K and is 4.5 billion years old. Kepler-1652 is about 1.6 to 2.6% as luminous as the Sun. The apparent magnitude of the star is 10.22.
Habitability
Kepler-1652b's placement within the habitable zone does not ensure its habitability. Multiple other factors are included, such as composition, atmosphere, and the amount of radiation the planet receives. Kepler-1652b has a temperature very similar to that of Earth, and gets about 81% the sunlight Earth does. This places it well within the conservative habitable zone and means it is unlikely to suffer a runaway greenhouse effect. While the planet is most likely tidally locked to its host star, which would create one hot side and one cold side, a thick atmosphere - if one exists - can distribute heat evenly around the planet, allowing for more areas to retain liquid water.
The high radius of Kepler-1652b decreases its chances of habitability. Most planets with radii of ≥1.6 are expected to either be entirely covered in thick oceans or be more akin to the ice giants like Uranus or Neptune. Without a rocky surface, life may never be able to develop on a planet. Red dwarfs like Kepler-1652 can produce very strong flares, much more powerful than what the Sun produces, which could erode away the atmosphere of orbiting planets, compromising their habitability. While not all red dwarfs are this active, a strong magnetic field can still help keep the worst of the host star's radiation from reaching the planetary surface, protecting any possible life.
See also
K2-3d and LHS 1140 b, two other high-density potentially habitable planets.
Mega-Earth
Habitability of red dwarf systems
References
Cygnus (constellation)
Exoplanets discovered in 2017
1652b
Transiting exoplanets
Super-Earths in the habitable zone | Kepler-1652b | [
"Astronomy"
] | 881 | [
"Cygnus (constellation)",
"Constellations"
] |
55,830,582 | https://en.wikipedia.org/wiki/Pump-areometer | The Pump-areometer was an early hydrometer (a variant of the syphon-hydrometer), credited to Floris Nollet.
Principle
The principle is an inverted glass tube with one leg in each of two liquids, the upper end being connected to a pump. Once sufficient air is removed from the pipe, the liquids rise in both legs, in inverse proportion to their density. If the density of one liquid is known, that of the other can be simply calculated. A reasonably wide tube is used to minimise the effects of capillary attraction.
More sophisticated "four leg" variants could eliminate the capillary effect on the calculation.
See also
Specific gravity
References
Measuring instruments
Laboratory equipment | Pump-areometer | [
"Technology",
"Engineering"
] | 142 | [
"Measuring instruments"
] |
55,831,248 | https://en.wikipedia.org/wiki/Semantic%20parsing | Semantic parsing is the task of converting a natural language utterance to a logical form: a machine-understandable representation of its meaning. Semantic parsing can thus be understood as extracting the precise meaning of an utterance. Applications of semantic parsing include machine translation, question answering, ontology induction, automated reasoning, and code generation. The phrase was first used in the 1970s by Yorick Wilks as the basis for machine translation programs working with only semantic representations. Semantic parsing is one of the important tasks in computational linguistics and natural language processing.
Semantic parsing maps text to formal meaning
representations. This contrasts with semantic role
labeling and other
forms of shallow semantic processing, which do
not aim to produce complete formal meanings.
In computer vision, semantic parsing is a process of segmentation for 3D objects.
History & Background
Early research of semantic parsing included the generation of grammar manually as well as utilizing applied programming logic. In the 2000s, most of the work in this area involved the creation/learning and use of different grammars and lexicons on controlled tasks, particularly general grammars such as SCFGs. This improved upon manual grammars primarily because they
leveraged the syntactical nature of the sentence, but they still couldn’t cover enough variation
and weren’t robust enough to be used in the real world. However, following the development
of advanced neural network techniques, especially the Seq2Seq model,
and the availability of powerful computational resources, neural semantic parsing started emerging. Not only was it providing competitive results on the existing datasets, but it was robust to noise and did not require a lot of
supervision and manual intervention.
The current transition of traditional parsing to neural semantic parsing has not been perfect
though. Neural semantic parsing, even with its advantages, still fails to solve the problem at a
deeper level. Neural models like Seq2Seq treat the parsing problem as a sequential translation problem, and the model learns patterns in a black-box manner, which means we cannot
really predict whether the model is truly solving the problem. Intermediate efforts and modifications to the Seq2Seq to incorporate syntax and semantic meaning have been attempted, with a marked improvement
in results, but there remains a lot of ambiguity to be taken care of.
Types
Shallow Semantic Parsing
Shallow semantic parsing is concerned with identifying entities in an utterance and labelling them with the roles they play. Shallow semantic parsing is sometimes known as slot-filling or frame semantic parsing, since its theoretical basis comes from frame semantics, wherein a word evokes a frame of related concepts and roles. Slot-filling systems are widely used in virtual assistants in conjunction with intent classifiers, which can be seen as mechanisms for identifying the frame evoked by an utterance. Popular architectures for slot-filling are largely variants of an encoder-decoder model, wherein two recurrent neural networks (RNNs) are trained jointly to encode an utterance into a vector and to decode that vector into a sequence of slot labels. This type of model is used in the Amazon Alexa spoken language understanding system. This parsing follow an unsupervised learning techniques.
Deep Semantic Parsing
Deep semantic parsing, also known as compositional semantic parsing, is concerned with producing precise meaning representations of utterances that can contain significant compositionality. Shallow semantic parsers can parse utterances like "show me flights from Boston to Dallas" by classifying the intent as "list flights", and filling slots "source" and "destination" with "Boston" and "Dallas", respectively. However, shallow semantic parsing cannot parse arbitrary compositional utterances, like "show me flights from Boston to anywhere that has flights to Juneau". Deep semantic parsing attempts to parse such utterances, typically by converting them to a formal meaning representation language. Nowadays, compositional semantic parsing are using Large Language Models to solve artificial compositional generalization tasks such as SCAN.
Neural Semantic Parsing
Semantic parsers play a crucial role in natural language understanding systems because they transform natural language utterances into machine-executable logical structures or programmes. A well-established field of study, semantic parsing finds use in voice assistants, question answering, instruction following, and code generation. Since Neural approaches have been available for two years, many of the presumptions that underpinned semantic parsing have been rethought, leading to a substantial change in the models employed for semantic parsing. Though Semantic neural network and Neural Semantic Parsing both deal with Natural Language Processing (NLP) and semantics, they are not same.
The models and executable formalisms used in semantic parsing research have traditionally been strongly dependent on concepts from formal semantics in linguistics, like the λ-calculus produced by a CCG parser. Nonetheless, more approachable formalisms, like conventional programming languages, and NMT-style models that are considerably more accessible to a wider NLP audience, are made possible by recent work with neural encoder-decoder semantic parsers. We'll give a summary of contemporary neural approaches to semantic parsing and discuss how they've affected the field's understanding of semantic parsing.
Representation languages
Early semantic parsers used highly domain-specific meaning representation languages, with later systems using more extensible languages like Prolog, lambda calculus, lambda dependency-based compositional semantics (λ-DCS), SQL, Python, Java, the Alexa Meaning Representation Language, and the Abstract Meaning Representation (AMR). Some work has used more exotic meaning representations, like query graphs, semantic graphs, or vector representations.
Models
Most modern deep semantic parsing models are either based on defining a formal grammar for a chart parser or utilizing RNNs to directly translate from a natural language to a meaning representation language. Examples of systems built on formal grammars are the Cornell Semantic Parsing Framework, Stanford University's Semantic Parsing with Execution (SEMPRE), and the Word Alignment-based Semantic Parser (WASP).
Datasets
Datasets used for training statistical semantic parsing models are divided into two main classes based on application: those used for question answering via knowledge base queries, and those used for code generation.
Question answering
A standard dataset for question answering via semantic parsing is the Air Travel Information System (ATIS) dataset, which contains questions and commands about upcoming flights as well as corresponding SQL. Another benchmark dataset is the GeoQuery dataset which contains questions about the geography of the U.S. paired with corresponding Prolog. The Overnight dataset is used to test how well semantic parsers adapt across multiple domains; it contains natural language queries about 8 different domains paired with corresponding λ-DCS expressions. Recently, semantic parsing is gaining significant popularity as a result of new research works and many large companies, namely Google, Microsoft, Amazon, etc. are working on this area. One on the recent works of Semantic Parsing for question answering is attached here. Shown in this picture is a representation of an example conversation from SPICE. The left column shows dialogue turns (T1–T3) with user (U) and
system (S) utterances. The middle column shows the annotations provided in CSQA. Blue boxes on the right show
the sequence of actions (AS) and corresponding SPARQL semantic parses (SP).
Code generation
Popular datasets for code generation include two trading card datasets that link the text that appears on cards to code that precisely represents those cards. One was constructed linking Magic: The Gathering card texts to Java snippets; the other by linking Hearthstone card texts to Python snippets. The IFTTT dataset uses a specialized domain-specific language with short conditional commands. The Django dataset pairs Python snippets with English and Japanese pseudocode describing them. The RoboCup dataset pairs English rules with their representations in a domain-specific language that can be understood by virtual soccer-playing robots.
Application Areas
Within the field of natural language processing (NLP), semantic parsing deals with transforming human language into a format that is easier for machines to understand and comprehend. This method is useful in a number of contexts:
Voice Assistants and Chatbots: Semantic parsing enhances the quality of user interaction in devices such as smart speakers and chatbots for customer service by comprehending and answering user inquiries in natural language.
Information Retrieval: It improves the comprehension and processing of user queries by search engines and databases, resulting in more precise and pertinent search results.
Machine Translation: To improve the quality and context of translation, machine translation entails comprehending the semantics of one language in order to translate it into another accurately.
Text Analytics: Business intelligence and social media monitoring benefit from the meaningful insights that can be extracted from text data through semantic parsing. Examples of these insights include sentiment analysis, topic modelling, and trend analysis.
Question Answering Systems: Found in systems such as IBM Watson, these systems assist in comprehending and analyzing natural language queries in order to deliver precise responses. They are particularly helpful in areas such as customer service and educational resources.
Command and Control Systems: Semantic parsing aids in the accurate interpretation of voice or text commands used to control systems in applications such as software interfaces or smart homes.
Content Categorization: It is a useful tool for online publishing and digital content management as it aids in the classification and organization of vast amounts of textual material by analyzing its semantic content.
Technologies related to accessibility: Helps create tools for the disabled, such as sign language interpretation and text to speech conversion.
Legal and Healthcare Informatics: Semantic parsing can extract and structure important information from legal documents and medical records to support research and decision-making.
Semantic parsing aims to improve various applications' efficiency and efficacy by bridging the gap between human language and machine processing in each of these domains.
Evaluation
The performance of Semantic parsers is also measured using standard evaluation metrics as like syntactic parsing. This can be evaluated for the ratio of exact matches (percentage of sentences that were perfectly parsed), and precision, recall, and F1-score calculated based on the correct constituency or dependency assignments in the parse relative to that number in reference and/or hypothesis parses. The latter are also known as the PARSEVAL metrics.
See also
Automatic programming
Class (philosophy)
Formal semantics (linguistics)
Information extraction
Information retrieval
Minimal recursion semantics
Process philosophy
Question answering
Semantic analysis (linguistics)
Semantic role labeling
Statistical semantics
Syntax
Type–token distinction
References
Tasks of natural language processing
Computational linguistics
Semantics
Parsing | Semantic parsing | [
"Technology"
] | 2,181 | [
"Natural language and computing",
"Computational linguistics"
] |
55,831,305 | https://en.wikipedia.org/wiki/Ministry%20of%20Oil%20Industry | The Ministry of Oil Industry (Minnefteprom; ) was a government ministry in the Soviet Union.
History
The Ministry of the Petroleum Industry was created by the 28 December 1948 ukase of the Presidium of the Supreme Soviet USSR merging the Ministry of the Petroleum Industry of the Southern and Western Regions, the Ministry of the Petroleum Industry of the Eastern Regions, Glavgaztoppron (Main Administration of Synthetic Liquid Fuel and Gas) and Glavneftegazstroy (Main Administration for the Construction of the Petroleum and Gas Industry) under the Council of Ministers USSR, and Glavneftesnab (Main Administration for the Supply of Petroleum Products to the National Economy) under Gossnab USSR (State Committee of the Council of Ministers USSR for Material and Technical Supply to the National Economy).
The Ministry of Petroleum Industry (People's Commissariat of Petroleum Industry prior to 15 March 1946) was established 12 October 1939 by ukase of the Presidium, Supreme Soviet USSR, and was subdivided on 4 March 1946 into the Ministry of the Petroleum Industry of the Southern and Western Regions of the USSR and the Ministry of the Petroleum Industry of the Eastern Region of the USSR.
Prior to 1939 it had been a part of the All-Union People's Commissariat of the Fuel Industry, established 24 January 1939 by ukase of the Presidium, Supreme Soviet USSR, as a result of the subdivision of the People's Commissariat of Heavy Industry USSR.
Organization
The Ministry of the Petroleum Industry was an all-Union ministry which administered the petroleum extraction, petroleum refining, and gas industries, the production of liquid fuels, the construction of installations for the petroleum and gas industries, the construction of petroleum-drilling machinery, and the marketing of petroleum products.
The Ministry of the Petroleum Industry was headed by a minister who directed the entire work of the Ministry of the Petroleum Industry and of the enterprises and organizations under its jurisdiction. The Minister of the Petroleum Industry issued, within the limits of his competence, orders and directives based on, and in execution of, existing laws, as well as of decrees and regulations of the Council of Ministers USSR, and he checked on their execution.
The Minister of the Petroleum Industry appointed directors of main administrations, administrations, and divisions of the Ministry and of the enterprises and organizations under its jurisdiction; he organized enterprises and organizations in accordance with established procedures; he approved statutes on main administrations, administrations, and divisions of the Ministry as well as the statutes and charters of organizations and enterprises under the jurisdiction of the Ministry.
A collegium was formed within the Ministry of the Petroleum Industry, consisting of the Minister (chairman), his deputies, and the supervisory personnel of the Ministry. The membership of the collegium was approved by the Council of Ministers USSR, upon recommendation of the Minister of the Petroleum Industry.
The collegium of the Ministry of the Petroleum Industry, at its regular sessions, considered questions of practical supervision, of checking on the execution of decisions, and of selection of personnel, as well as the most important orders and directives of the Ministry; it hears the reports of the directors of main administrations, administrations, and divisions of the Ministry and of organizations and enterprises under its jurisdiction.
The decisions of the collegium are carried out by orders of the Minister. The basic task, for the carrying out of which the Ministry of the Petroleum Industry is responsible, is to assure the development of the petroleum industry in accordance with plans approved by the USSR government, with the goal of completely satisfying the requirement of the rational economy for petroleum products and gas.
This goal was to be achieved by the introduction of the most modern equipment, by mechanizing and automatizing production processes in the extraction and refining of petroleum and gas, by the construction of oil fields, refineries, gas plants, plants for the production of synthetic liquid fuels, pipelines and petroleum tanks by the development of petroleum machinery building, by the creation of permanent cadres of qualified workers, engineers, and technicians, by increasing labor productivity, and by improving the quality of production and reducing its costs. The Ministry of the Petroleum Industry prepares production plans (prospective, yearly, quarterly), plans for capital construction, marketing, and railroad and water transport, as well as for balancing income and expenditures.
It submitted these plans for ratification by the Council of Ministers USSR in accordance with established procedure, and it takes measures toward the fulfillment of plans that have been ratified.
Role
The Ministry of the Petroleum Industry organized the prospecting and surveying of new petroleum, gas, and ozocerite deposits by geological, geophysical, and geochemical surveying methods. It takes measures to increase labor productivity, to improve the quality of production, and to reduce the cost of production and construction. It exercises technical and production supervision over enterprises of the Ministry, and introduces the most modern equipment, technical improvements and inventions, mechanization and automation of production processes, and established norms for the consumption of materials, power and fuel.
It drafts plans for production standards in branches of industry under the jurisdiction of the Ministry- and submits them for ratification according to established procedure. The Ministry directs the construction of enterprises and installations of the petroleum industry and, in accordance with established procedure, ratifies planned quotas, technical plans, and estimates for capital construction. It organizes and supervises the material and technical supply of enterprises, organizations, and installations. It supervises the operations of enterprises which produce industrial and construction materials required by branches of industry under the jurisdiction of the Ministry.
The Ministry handled the sales of petroleum products produced by enterprises of the Ministry of the Petroleum Industry through a system of administrations and petroleum bases of Glavneftesbyt (Main Administration of Petroleum Sales).
It selected the personnel of the Ministry, takes measures to provide enterprises and construction projects of the Ministry with personnel and to utilize them properly, at the same time providing for their living conditions.
It draws up regulations on the wages of workers, engineers, technicians, and employees of the enterprises, submits them for ratification by the Council of Ministers USSR, in accordance with established procedure, and supervises their application. It determines technical norms and the revision of output norms (except for the basic revision of norms carried out with the permission of the government), and checks on their fulfillment.
It supervised the observance of labor legislation and rules for accident prevention. It directs the conclusion of collective contracts and checks on their fulfillment. The Ministry directs socialist competition to develop the creative initiative of workers, engineers, and technicians, to increase labor productivity further, to fulfill production plans ahead of schedule, to improve the quality of production, to increase profits of the enterprises, and to acquire above-plan accumulations.
It financed the enterprises and organizations of the Ministry in accordance with established procedure, supervises their financial activity, and takes measures to speed up the turnover of working capital and to increase the profits of the enterprises. It supervises the organization and system of accounting, approves balances and reports of main administrations and organizations under the direct jurisdiction of the Ministry, and draws up periodic and yearly accounting records for all types of industrial and administrative activity of the Ministry.
It exercised financial control and makes documentary revisions in the administration of the Ministry. It administers scientific research institutes under the jurisdiction of the Ministry, planning organizations, and educational establishments and directs the training of workers in the mass professions. It directs the activity of administrations and divisions of labor supply and subsidiary economies.
It takes measures for the protection of state socialist, property in enterprises, establishments, and organizations under the Ministry. It publishes literature on the technology, economics, and organization of the petroleum and gas industries. The structure of the Ministry of the Petroleum Industry is determined by the Council of Ministers USSR to utilize to the best advantage outstanding experiences of directors, ordinary workers, and Stakhanovites, the Ministry of the Petroleum Industry, its chain administrations associations, trusts and enterprises summon meetings at which reports are heard and discussed dealing with the most important party and government decisions as well as administrative directives of the Ministry. To develop criticism and self-criticism, questions on the activity of production and management are also discussed.
List of ministers
Source:
References
Oil Industry
Energy ministries | Ministry of Oil Industry | [
"Engineering"
] | 1,662 | [
"Energy organizations",
"Energy ministries"
] |
55,831,826 | https://en.wikipedia.org/wiki/Irina%20Mansurova | Irina Jafarovna Mansurova () (15 November 1925 – 6 April 1991) was a Tajikistani biochemist.
Born in Bukhara, Mansurova was a graduate of the Samarkand Medical Institute, from which she received her degree in 1948. From 1951 to 1959 she interned in the Department of Contagious Diseases at the Tajikistan State Medical Institute. In the latter year she became a Senior Scientific Worker, and until 1976 was director of the Biochemistry Division of Medical Research of the Tajik SSR. In 1967 she became a doctor of medicine, become a professor two years later. In 1976, she took over directorship of the biochemical laboratories of the Nature Preservation Division of the Tajikistan Academy of Sciences. In 1960 she was among those who participated in the foundation of the Department of Biochemistry at the Institute of Gastroenterology of the Academy of Sciences. She was the first Soviet scientist to discover principles governing the resolution of microchemical points on the liver; she also worked with the varied ferment constellations, and studied the effects of herbal medicine on organisms. She supervised the publication of the three-volume Experimental Liver Pathology, and herself published such works as The Biochemistry of the Liver During Hepatitis and Psoriasis of the Liver (Dushanbe, 1964) and Selected Lectures About Biochemistry (Dushanbe, 1971); ultimately she published 240 papers during her career, including three monographs. Named a Distinguished Contributor to Health Services of the Soviet Union in 1967, she received a number of medals during her career. Mansurova was married to the therapist Hamid Mansurov; their daughter Farida became a noted biochemist in her own right, and later took over directorship of the Department of Biochemistry at the Institute of Gastroenterology.
References
1925 births
1991 deaths
Tajikistani biochemists
Tajikistani women scientists
People from Bukhara
Women biochemists
20th-century women scientists
Soviet women physicians
Soviet biochemists | Irina Mansurova | [
"Chemistry"
] | 394 | [
"Biochemists",
"Women biochemists"
] |
55,831,856 | https://en.wikipedia.org/wiki/Termitomyces%20eurrhizus | Termitomyces eurrhizus species of agaric fungus in the family Lyophyllaceae native to Pakistan, India, Sri Lanka, Burma, southwestern China and Malaysia. The fungus has a symbiotic relationship with termites, its mushrooms growing out of mounds after periods of rainfall. It is eaten in Malaysia and the Indian subcontinent.
Taxonomy
Miles Joseph Berkeley named the fungus in 1847 as Agaricus eurrhizus, from material collected in Peradeniya in Sri Lanka. French botanist Roger Heim reclassified the species as Termitomyces eurrhizus in 1942. Its place in Termitomyces was confirmed with a 2000 ribosomal DNA study showing that the termite mushrooms form a clade.
Description
The cap is from 6–15 cm across, with rare specimens up to 24 cm in diameter. Grey-brown and fading to whitish at the margins, the cap is initially convex before expanding out with a central boss. The crowded white gills are free to subadnate. The ringless stout white stem is up to 20 cm high and 1.5 to 2.5 cm across. It continues into the soil. The spore print is pink, and the oval spores are 6.8–9.3 μm long by 5.1–6.8 μm wide.
Distribution, habitat and ecology
Widely distributed, T. eurrhizus has been recorded from Pakistan, India, Sri Lanka, Burma, southwestern China and Malaysia. Like other members of the genus, the mushrooms grow out of termite mounds. T. eurrhizus is associated with the termite species Macrotermes gilvus in Selangor, Malaysia, and Odontotermes badius in Sri Lanka. The fungus and the termites have a complex symbiotic relationship. The termites cultivate the fungus on plant material within the mound, which they eat. The nutrients in their food are made more digestible by the fungus. After rain, the fungus is triggered into producing large mushrooms that grow and spread spores elsewhere.
Consumption
In October 1972, it was recorded as being sold in markets in Midnapore in West Bengal. In the northern Malaysian state of Kedah, it is eaten by locals and known as cendawan kaki lembu "cattle leg mushroom".
References
Lyophyllaceae
Fungi described in 1847
Fungi of China
Fungi of India
Taxa named by Miles Joseph Berkeley
Fungus species | Termitomyces eurrhizus | [
"Biology"
] | 499 | [
"Fungi",
"Fungus species"
] |
55,832,622 | https://en.wikipedia.org/wiki/Heimioporus%20retisporus | Heimioporus retisporus is a species of bolete fungus found in China. It is the type species of the genus Heimioporus.
References
retisporus
Fungi of China
Fungus species | Heimioporus retisporus | [
"Biology"
] | 44 | [
"Fungi",
"Fungus species"
] |
55,833,356 | https://en.wikipedia.org/wiki/Trenbolone%20undecanoate | Trenbolone undecanoate, or trenbolone undecylate, is a synthetic and injected anabolic–androgenic steroid (AAS) and a derivative of nandrolone (19-nortestosterone) which was never marketed. It is the C17β undecanoate (undecylate) ester and a long-acting prodrug of trenbolone. The drug was described by Roussel Uclaf in 1967 and was the first long-lasting ester of trenbolone to be developed. Subsequently, trenbolone hexahydrobenzylcarbonate, a roughly equivalent compound, was developed and introduced for use in humans in 1980, though it was discontinued in 1997. Trenbolone enanthate is another long-lasting ester of trenbolone. Similarly to trenbolone undecanoate, it was never marketed, but it has been sold on the black market as a designer steroid for bodybuilders and athletes.
See also
List of androgen esters § Trenbolone esters
References
Further reading
Abandoned drugs
Androgen esters
Anabolic–androgenic steroids
Estranes
Ketones
Sex hormone esters and conjugates
Progestogens
Undecanoate esters | Trenbolone undecanoate | [
"Chemistry"
] | 275 | [
"Ketones",
"Functional groups",
"Drug safety",
"Abandoned drugs"
] |
55,833,777 | https://en.wikipedia.org/wiki/Mesterolone%20cipionate | Mesterolone cipionate is a synthetic anabolic–androgenic steroid and an androgen ester – specifically, the C17β cypionate ester of mesterolone – which was never marketed. It is administered via intramuscular injection once every two weeks and acts as a long-acting prodrug of mesterolone. The drug was studied in the treatment of depression in men along with mesterolone in the mid-1970s but was never introduced for medical use.
See also
List of androgen esters
References
Abandoned drugs
Androgen esters
Anabolic–androgenic steroids
Androstanes
Cypionate esters
Ketones
Prodrugs | Mesterolone cipionate | [
"Chemistry"
] | 145 | [
"Ketones",
"Functional groups",
"Drug safety",
"Prodrugs",
"Chemicals in medicine",
"Abandoned drugs"
] |
55,835,082 | https://en.wikipedia.org/wiki/Gunning%20Victoria%20Jubilee%20Prize | The Gunning Victoria Jubilee Prize Lectureship is a quadrennial award made by the Royal Society of Edinburgh to recognise original work done by scientists resident in or connected with Scotland.
The award was founded in 1887 by Dr Robert Halliday Gunning, a Scottish surgeon, entrepreneur and philanthropist who spent much of his life in Brazil.
Awards by a similar name have also been awarded by the University of Edinburgh.
Prizewinners
Source: Royal Society of Edinburgh
1887: Sir William Thomson, for a series of papers on Hydrokinetics
1887–1890: Peter Guthrie Tait, for work done on the Challenger Expedition
1890–1893: Alexander Buchan, for his contributions on meteorology
1893–1896: John Aitken, for his work on the formation and condensation of aqueous vapour
1896–1899: Rev. Thomas David Anderson, for his discoveries of new and variable stars
1900–1904: Sir James Dewar, for his researches on the liquefaction of gases
1904–1908: George Chrystal, for a series of papers on Seiches
1908–1912: John Norman Collie, for his contributions to organic and inorganic chemistry
1912–1916: Thomas Muir, for his memoirs on the theory and history of determinants
1916–1920: Charles Thomson Rees Wilson, for his studies in connection with condensation nuclei, ionisation of gases and atmospheric electricity
1920–1924: Sir Joseph John Thomson, for his discoveries in physics
1924–1928: E.T. Whittaker, for his contributions to mathematics
1928–1932: Sir James Walker, for contributions to physical and general chemistry
1932–1936: Charles Galton Darwin, for his contributions to mathematical physics
1936–1940: James Colquhoun Irvine, for contributions to organic chemistry
1940–1944: Herbert Westren Turnbull, for his contributions to mathematical science
1944–1948: Max Born, for contributions to theoretical physics
1948–1952: Alexander Craig Aitken, for his contributions to pure mathematics
1952–1956: Harry Melville, for contributions to reaction kinetics and physics and chemistry of high polymers
1956–1960: Sir Edward Victor Appleton, contributions to ionospheric and radio physics
1960–1964: Sir Edmund Hirst, for contributions to the chemistry of carbohydrates
1964–1968: Sir William Vallance Douglas Hodge, for contributions to geometry
1968–1972: Philip Ivor Dee, for contributions to nuclear physics
1972–1976: Arthur Erdelyi, for contributions to mathematics especially the theory of special functions
1976–1980: Charles Kemball, for contributions to the study of analysis
1984: Nicholas Kemmer, for his contributions to the theory of elementary particles
1988: Sir Michael Atiyah, for his contribution to mathematics
1992: Peter Ludwig Pauson, for his contributions to the chemistry of diene- and triene-metal carbonyl complexes
1996: Kathryn A Whaler, for her contribution to the development of mathematical models on the long wave length component of the geomagnetic field
2000: Angus Macintyre, for his contributions to logic, model theory, algebra, analysis and computer science
2004: Peter George Bruce, for contributions to solid state chemistry
2008: James Hough, for his work on gravitational waves
See also
List of general science and technology awards
List of mathematics awards
References
British science and technology awards
Mathematics awards
Royal Society of Edinburgh
Scottish awards
1887 establishments in Scotland
Awards established in 1887 | Gunning Victoria Jubilee Prize | [
"Technology"
] | 689 | [
"Science and technology awards",
"Science award stubs",
"Mathematics awards"
] |
55,835,384 | https://en.wikipedia.org/wiki/Porhalaan | The Porhalaan is the traditional calendar of the Batak people of North Sumatra, Indonesia. The Batak Calendar is a lunisolar calendar consisting of 12 months divided to 30 days with an occasional leap month. The Batak calendar is derived from Hindu calendar. The Batak people do not use the porhalaan as a mean to tell time, but rather to determine auspicious day, which is only used by the Batak shaman.
Ritual
The name porhalaan came from the word hala, which is derived from Sanskrit kala, "scorpion", as the practice put observation of constellations into account. The porhalaan is used by the Batak people for divination. Batak people did not use the porhalaan for telling time. The responsibility of interpreting the porhalaan fell solely to the chief male ritualist known as the datu. The datu would read the porhalaan to determine which day is considered auspicious or inauspicious to hold a certain ritual.
In order to minimize the risk of accidentally selecting an unfavorable day due to errors in calendar management, days are often chosen based on whether the day is able to promise happiness in two months time, probably the current month and the following one. There is often an extra 13th month in the calendar that serves this purpose, originally a Hindu leap year, but in the Batak context, it is used for a different reason. If the additional 13th month is not available, then the first month is simply used again for protection. Whether the 13th month is used to compensate for the difference to the solar year is not proven in the context of Batak society.
The Porhalaan is usually written as a table of square boxes of 30 columns (days) of 12 or 13 rows (months) as recorded in the pustaha, the Batak magic book. Sometimes the porhalaan is written on a cylindrical piece of bamboo.
The Porhalaan is the clearest example of the Batakization of Hindu culture. The original Hindu Calendar was borrowed, modified and reworked according to Batak empirical and pragmatic principles. The result is a simplification of the original calendar. All that remains of a complicated system of adjusting lunar months to the solar Zodiac is a divination calendar which is not used for the purpose of telling times.
Calendar system
There is no designation of year in Batak Calendar. New Year begins on the New Moon in May, when the constellation Orion (siala sungsang) vanishes in the west and the constellation Scorpius (siala poriama) rises in the east.
Porhalaan is divided into 12 months, each contains 30 days. Each month was named by its number, the first month is called simply "first month" or bulan si pahasada, second month is bulan si pahadua, etc. The eleventh month is called bulan li, while the twelfth month is named bulan hurung. The first day of each month (bona ni bulan) fell directly one day after the New Moon. The Full Moon usually fell on the 14th or 15th day.
Porhalaan do not use the term for "week", but each month is divided into four each containing seven days. The name of each of the seven days was borrowed from the Sanskrit name. The first day is called Aditya ("sun"), the second Soma ("moon"), Anggara (Mars), Budha (Mercury), Brihaspati (Jupiter), Syukra (Venus), and Syanaiscara (Saturn). In the porhalaan way of naming days, the name of the day in the context of '30 days of a month' is maintained. For example, the third day in a month which fell on Tuesday is known Nggara telu uari. sixth day is Cukera enem berngi, ninth is Suma na siwah, tenth is Nggara sepuluh, and so on. The 7th, 14th, 21st, and 28th day is named after the moon phase, that is bělah (first quarter waxing moon), bělah purnama (full moon), bělah turun (third quarter waning moon), dan mate bulan (dead moon). The word pultak ("increasing") is added to the bright fortnight days of the porhalaan when the moon phase grows, while the word cěpik ("decreasing") is added to the dark fortnight days of the porhalaan when the moon phase decreases; this is obviously influenced by the Hindu shukla pasha and krishna paksha.
See also
List of calendars
References
Cited works
Calendars
Batak | Porhalaan | [
"Physics"
] | 973 | [
"Spacetime",
"Calendars",
"Physical quantities",
"Time"
] |
55,835,640 | https://en.wikipedia.org/wiki/Europium%28III%29%20nitrate | Europium(III) nitrate is an inorganic compound with the formula . The hexahydrate is a common salt. It forms colorless hygroscopic crystals.
Preparation
The salt is usually obtained by dissolving europium(III) oxide (Eu2O3) in nitric acid produces europium(III) nitrate.
Eu2O3 + 6 HNO3 → 2 Eu(NO3)3 + 3 H2O
Structure
Like all trinitates of the lanthanides, dilute (<0.01 M) solutions of consists of the aquo complex where x = 8 or 9. At higher concentrations, the binding of nitrate to Eu is observed.
Complexes
Europium(III) nitrate reacts with anions and other Lewis bases to form complexes. For example, with 1,3,5-trimesic acid, europium metal-organic framework, a coordination polymer, under hydrothermal conditions.
References
Europium(III) compounds
nitrates | Europium(III) nitrate | [
"Chemistry"
] | 210 | [
"Oxidizing agents",
"Nitrates",
"Salts"
] |
55,835,838 | https://en.wikipedia.org/wiki/Himanshu%20Pandya | Himanshu Pandya is an Indian professor and academic at Botany Department Gujarat University, Ahmedabad, Gujarat, India. He earned a MSc and PhD in botany and areas of specialization In vivo and In vitro studies on physiological and biochemical parameters on Gladiolus, Chrysanthemum and Lily.
Career
Pandya taught for 27 years. He is also a professor and Head of the Department of Biochemistry and Forensic Science. His research focused on horticulture, plant biotechnology, plant physiology, plant biochemistry, bioinformatics, climate change and impacts management, forensic science, and biochemistry.
From 2005 - 2017 he was a Professor in the Department of Botany, Bioinformatics and Climate Change Impacts Management.
In 2017 he became Vice Chancellor of the Gujarat University.
References
Living people
Academic staff of Gujarat University
Year of birth missing (living people)
Botany | Himanshu Pandya | [
"Biology"
] | 172 | [
"Plants",
"Botany"
] |
55,836,439 | https://en.wikipedia.org/wiki/HD%2056405 | HD 56405 is a star in the southern constellation of Canis Major. It is white in hue and is dimly visible to the naked eye with an apparent visual magnitude of 5.45. To the east of HD 56405 is the open cluster NGC 2360, also known as Caroline's Cluster. The distance to HD 56405, as determined from parallax measurements, is approximately 249 light years. It is drifting further away with a radial velocity (RV) of about +6 km/s. Although classed as a single star, it is to suspected to vary in RV.
This is an A-type main-sequence star with a stellar classification of A1V. It was classed as a candidate Lambda Boötis star, but as of 2015 this classification has been rejected by astronomers due to the star having an inconsistent UV flux, possible RV variability, and a fairly high rotation rate. The star is about 212 million years old with 2.13 times the mass of the Sun and is spinning with a projected rotational velocity of 149 km/s. It is radiating 39 times the luminosity of the Sun from its photosphere at an effective temperature of around 9,562 K.
References
A-type main-sequence stars
Canis Major
Durchmusterung objects
056405
035180
2758
Gliese and GJ objects | HD 56405 | [
"Astronomy"
] | 278 | [
"Canis Major",
"Constellations"
] |
55,836,547 | https://en.wikipedia.org/wiki/WASP-47 | WASP-47 is a star similar in size and brightness to the Sun about 881 light-years away in the constellation Aquarius. It lies within the Kepler K2 campaign field 3. It was first noticed to have a hot Jupiter exoplanet orbiting every 4 days in 2012 by the Wide Angle Search for Planets (WASP) team. While it was thought to be a typical hot Jupiter system, three more planets were found in 2015: an outer gas giant within the habitable zone, a hot Neptune exterior to the hot Jupiter's orbit and a super-Earth interior to the hot Jupiter's orbit. WASP-47 is the only planetary system known to have both planets near the hot Jupiter and another planet much further out.
Nomenclature and history
Prior to the discovery of its planets, WASP-47 was given the 2MASS designation of 2MASS J22044873-1201079. It was also observed by the Wide-field Infrared Survey Explorer and given the designation WISE J220448.74-120108.4. When observed by NASA's K2 mission, it was given the Ecliptic Plane Input Catalog designation of EPIC 206103150, and later named K2-23 after the discovery of planets d and e.
In 2012, a team from the SuperWASP group, led by Coel Hellier, announced the discovery of a Hot Jupiter exoplanet, with the designation WASP-47b, orbiting every 4.17 days. Three years later in 2015, Neveu-Van Malle et al. found a second planet, WASP-47c, orbiting within the habitable zone of the system using the HARPS spectrograph at the La Silla Observatory in Chile. Using data from NASA's K2 mission a Planet Hunters volunteer discovered multiple planets around WASP-47 and after analysing the data the researchers (Becker et al. 2015) published the two additional transiting planets, the Hot Neptune WASP-47d and the Mega-Earth WASP-47e, orbiting near WASP-47b.
Stellar characteristics
WASP-47 is a G-type main-sequence star of spectral type G9V, making it quite similar to the Sun. It is 1.11 and 1.16 , with a temperature of 5576 K and an age of about 6.5 billion years. In comparison, the Sun has a slightly higher temperature of 5778 K but is significantly younger, at 4.5 billion years old.
The star is very metal-rich, with a metallicity ([Fe/H]) of about +0.36, or about twice the amount of iron and other elements heavier than Hydrogen and Helium than the Sun. This would explain how two massive gas giants, as well as a Mega-Earth, were able to form around the same star. WASP-47 is estimated to have a luminosity of 1.16 .
The star's apparent magnitude, or how bright it appears from Earth's perspective, is around 12. Therefore, it is far too faint to be seen with the unaided eye.
Planetary system
WASP-47 has a diverse and complex system of four planets. Three of them – e, b, and d – transit the host star, while WASP-47c was found with the radial velocity method. The first three have widely varying sizes, between 1.8 and 13 times the radius of Earth. They are also much more massive than Earth, with the least massive WASP-47e at 6.8 . Both gas giants are significantly more massive than Jupiter, at 1.2 and 1.57 , respectively. In comparison, Jupiter is about 318 . However, because of observation effects from Earth's turbulent atmosphere, the mass values for all four planets have relatively high uncertainties, with WASP-47c having the greatest uncertainty. Despite that, the compositions for the planets are well-constrained. WASP-47e has almost no volatile materials (water, hydrogen/helium), d has a thin gaseous envelope, and b and c are both gas giants like Jupiter and Saturn.
The presence of two rather small planets, as well as the orbital configuration of the first three planets, is not expected for Hot Jupiter systems, as a migrating gas giant is thought to kick out any small inner planets. In order for the system to come out the way it is now, the two gas giants likely would have to have formed before the lower-mass planets e and d. This is called two-stage planetary formation, and is hypothesized to have happened in the Solar System as well. It is hypothesized that WASP-47b would have moved inwards and brought planet-forming material close to the star. Once most of the gas dissipates, the two gas-poor planets form nearby the large Hot Jupiter.
Planets e, b, and d have very similar orbits, with orbital periods of 0.8, 4.2, and 9.1 days, respectively. All of them are very hot (≥1000 K) and have very low orbital eccentricities, even lower than those of Earth. In stark contrast to the inner planets, c has an eccentric orbit (e = 0.36) lasting over 580 days within the habitable zone of its host star. The high eccentricity can't be explained by the inward migration of WASP-47b, and there isn't any secondary star to cause it. The only likely remaining explanation is that another massive planet altered the orbit of WASP-47c that is either further out in the system or was ejected billions of years ago.
See also
Planetary migration
Nice model
55 Cancri e, another large rocky planet very similar to WASP-47e.
References
G-type main-sequence stars
Aquarius (constellation)
J22044873-1201079
Planetary systems with four confirmed planets
Planetary transit variables | WASP-47 | [
"Astronomy"
] | 1,211 | [
"Constellations",
"Aquarius (constellation)"
] |
55,837,397 | https://en.wikipedia.org/wiki/Jan%20D%C5%82ugosz%20Award | The Jan Długosz Award (Polish: Nagroda im. Jana Długosza) is a Polish literary prize which has been presented annually since 1998 during the Kraków Book Fair. It is named in honor of Polish medieval chronicler Jan Długosz (1415–1480) and its aim is to popularize works in the field of humanities written by Polish authors and published the previous year which make significant contributions to the advancement of science and cultural enrichment. The award recognizes books not only targeted to the professional, scientific circles but also to the general reader, which is intended to make them the subject of a broader public debate. The winners of the award receive cash prizes and a statuette designed by sculptor Bronisław Chromy.
List of Laureates
See also
Gall Anonim
Wincenty Kadłubek
History of Poland
References
Science writing awards
Polish literary awards
Awards established in 1998 | Jan Długosz Award | [
"Technology"
] | 188 | [
"Science and technology awards",
"Science writing awards"
] |
55,837,994 | https://en.wikipedia.org/wiki/Overbore | Overbore cartridges are those with a relatively large case volume or case capacity, coupled with a relatively small diameter bullet.
The case volume or case capacity and barrel bore area can be mathematically related to obtain a case volume to bore area ratio in metric or imperial units.
where:
= the cartridge case internal volume or case capacity (in ml or (for non-metric users) grains of water)
= barrel bore cross section area (in cm2 or in2)
The higher the Oratio result, the more overbore a cartridge will be. As the ratio is expressed in units of length, relatively high Oratio is a good predictor of suitability for relatively long barreled guns.
Oratio is also used to predict barrel life in cartridges of the same caliber, but not of different calibres, since the ratio is an extensive quantity that does not correlate to temperature or pressure (e.g. a .50 cal straight cartridge may have the same overbore as a highly necked down .17 cal cartridge).
Comparative index for various rifle cartridges
The bore cross section areas "Q" used in the calculations were taken from the appropriate C.I.P. data sheets.
The intermediate cartridges .30 Carbine, 7.92×33mm Kurz, 7.62×39mm, 7.62×45mm, 5.45×39mm, .223 Remington/5.56×45mm NATO and 5.8×42mm stand out as having relatively low sub 8 Oratio's.
References
“Overbore” Cartridges Defined by Formula Can a Formula Provide a Useful Index Ranking of Overbore Cartridges? http://www.accurateshooter.com
Firearms
Firearm terminology
Ammunition
Ballistics | Overbore | [
"Physics"
] | 360 | [
"Applied and interdisciplinary physics",
"Ballistics"
] |
44,210,893 | https://en.wikipedia.org/wiki/National%20Development%20Programme%20in%20Computer%20Aided%20Learning | The National Development Programme in Computer Aided Learning (NDPCAL) was the earliest large-scale education programme in the United Kingdom to explore the use of computers for teaching and learning.
First proposed in 1969 to the Department of Education and Science by the National Council for Educational Technology. it ran from 1973 to 1977 spending £2.5M to support some 35 projects covering a range of subjects.
About half the money was spent on projects in universities and the rest on projects in schools, colleges, industrial and military training. Richard Hooper was appointed its Director and operated with a small central team and the programme was administered by the Council for Educational Technology.
Origins
During the 1960s various projects in the US and the UK using mainframe and minicomputers began to develop the field of Computer Aided Learning and there was much debate about its value and effectiveness. The National Council for Educational Technology produced advice to government in 1969 to run a national development programme to explore the value of these approaches.
The Department for Education and Science (DES) announced in 1972 the approval by then Secretary of State Margaret Thatcher of a "national development programme in computer assisted learning." Following the announcement of the programme, the post of director was advertised and Richard Hooper was selected.
Strategy
NDPCAL's strategy was to work mainly with existing projects in Computer Aided Learning but also to develop feasibility projects with those with good ideas. It required joint funding from the host establishment and stipulated effective evaluation and monitoring processes but allowed a significant degree of autonomy to the projects. The approach of the central team was active and interventionist, working alongside potential projects in their early stages to help develop their design and approach. They required four monthly accounting periods and carefully controlling expenditure.
Governance
CET was asked to provide administrative services to the new programme, and the programme's central staff were CET employees but executive control was with a committee made up of civil servants from seven government departments plus a group of co-opted advisers. This programme committee was chaired by the DES and held the final say on proposals from the programme director. It also involved itself in project evaluation, setting up sub-committees of three or so of its members to look in detail at a particular proposal or project. Although each of the thirty projects had its own steering committee national linkage was maintained through a member of the national programme committee sitting on each project steering committee.
Setting Up
From January 1973 to early summer 1973, there was a phase of exploration and consultation and from the summer of 1973 to the end of the year, there was the setting up of the programme's management structure and of the first generation of major projects, notably in the university sector. Hooper was supported by two assistant directors, Gillian Frewin (from ICL) and Roger Miles (from the Army School of Instructional Technology). They were supported by two other executive posts and three secretaries.
The programme formulated two main aims over its lifetime (Hooper, 1975, p17):
to develop and secure the assimilation of computer assisted and computer managed learning on a regular institutional basis at reasonable cost
to make recommendations to appropriate agencies in the public and private sector (including Government) concerning possible future levels and types of investment in computer assisted and computer managed learning in education and training.
Two evaluations were set up, one to consider the educational benefits and one to consider the financial aspects.
Breadth of Projects
This first government funded programme focused on their use for learning subjects other than programming. It supported some 35 projects, seven in schools, a number in higher education but the majority were based on the British armed services’ growing interest in developing more automated and managed approaches to training. The hardware was limited; the computers were large expensive cabinets of complicated electronics accessed mainly by paper tape with Teletype printouts but already the focus was more on the way technology could be used to improve teaching and learning than as a subject in its own right.
NDPCAL funded a wide range of different projects - of different types, covering a range of subjects and age ranges sectors. Some of these, such as Chelsea College's computers in the undergraduate science curriculum, developed into the computers in the curriculum project and Hertfordshire's computer-managed mathematics helped the Advisory Unit for Computer Based Education (AUCBE) at Hatfield develop.
It classified projects into different stages
Stage 1 - Design and Feasibility - a project that shows that a particular application of CAL or CML is feasible by developing and piloting applications.
Stage 2 - Development and Transferability - the creation of a working system for increasing numbers of students across a number of institutions.
Stage 3 - Model Operation - a fully operational project able to act as a model for others.
Stage 4 - Assimilation and Dissemination - national funding is being phased out and the institution has taken ownership with other new institutions taking it up.
About half the project funds were spent on projects in universities and polytechnics, about one-sixth of the project funds was spent on schools based projects and the rest on military and industrial training. Some of the projects are listed below.
Computer Based Learning Project on Applied Statistics for Social Science, Leeds University - Director: J.R. Hartley
Computer Assisted Learning in Engineering Sciences Director: Dr. P.R. Smith Faculty of Engineering, Computer Assisted Teaching Unit, Queen Mary College.
Computer Assisted Learning in Chemistry Director: Dr. P.B. Ayscough Dept. of Physical Chemistry, The University of Leeds.
Computers in the Undergraduate Science Curriculum Director: Dr. I. McKenzie, University College London
Hertfordshire Computer Managed Mathematics in Schools Director: Dr. W.Tagg, Advisory Unit for Computer Based Education
Evaluation
NDPCAL set up two independent evaluations: an educational evaluation carried out by the University of East Anglia and a financial evaluation by Peat, Marwick, Mitchell and Co.
The Educational Evaluation, UNCAL (Understanding Computer Assisted Learning) was carried out over a period of three years evaluation project and reported findings about CAL in general. Its findings echo many of the later findings of the effectiveness of e-learning :
It is the versatility of the computer as an aid that assures its educational future
CAL, like most innovation, provides an add-on experience at an add-on cost
Much of the learning seen within NDPCAL fell into the category of higher-order learning
CAL is a demanding medium for learning - virtually guaranteeing the students engagement
Some forms of CAL enforce a strict role of learner on the student - this may need to be complemented by other forms
CAL offers the student uninhibited learning opportunities within a 'privacy of risk'
Learning may be inhibited by interface problems - where the student needs to put extra effort into keyboard skills, learning new computer protocols
Current CAL still requires more adaption of the student to the machine
Students like working on CAL but are frustrated by technical problems
CAL is change-oriented not efficiency-oriented
CAL supports teacher development since it encourages a team approach
At present CAL development requires access to high level computer expertise.
The financial evaluation reported some tentative but interesting conclusions in their study that again reflect later findings on e-learning:
CAL will always be an extra cost
There are no realisable cash savings or benefits from CAL
Claims that CAL will 'save' academic staff time are oversimplified and unjustifiable
The time taken to develop science packages varies between 200 and 400 hours
Inter-institutional development has been a success leading to substantial savings
Large scale applications of CAL require full-time staff and regular computer time.
They calculated the 'national or total cost per student terminal hour' in the range £4-£15 by comparison the cost of conventional teaching was in the range £0.60-£2.50 per student hour.
References
Computer-aided design
Education in the United Kingdom
Educational technology projects
Governmental educational technology organizations
Information technology organisations based in the United Kingdom
United Kingdom educational programs | National Development Programme in Computer Aided Learning | [
"Engineering"
] | 1,563 | [
"Computer-aided design",
"Design engineering"
] |
44,210,894 | https://en.wikipedia.org/wiki/Drinking%20fountains%20in%20the%20United%20States | This is a history and list of drinking fountains in the United States. A drinking fountain, also called a water fountain or bubbler, is a fountain designed to provide drinking water. It consists of a basin with either continuously running water or a tap. The drinker bends down to the stream of water and swallows water directly from the stream. Drinking water fountains are most commonly found in heavy usage areas like public amenities, schools, airports, and museums.
History
The first of the drinking fountains in Philadelphia may rank among the earliest in the country. Constructed in 1854, it was explicitly labeled "For the public good", it had respectable neo-classical detailing, and it was privately funded, all of which would set a pattern. It was described in 1884 as:
The first fountain, so called, stands upon the side of the road on the west side of the Wissahickon … It is claimed that this is the first drinking fountain erected in the county of Philadelphia outside of the Fairmount Water-Works. A clear, cold, mountain spring is carried by a spout, covered with a lion's head, from a niche in a granite front, with pilasters and pediment into a marble basin. The construction bears the date 1854 … Upon a slab above the niche are cut the words "Pro bono publico"; beneath the basin these, "Esto perpetua".
In the late 1860s, a mix of progressive organizations and private philanthropists began funding purpose-built, public water fountains. Early examples include the first fountain funded by the new American Society for the Prevention of Cruelty to Animals in 1867, in Union Square in New York City, and the work of the Philadelphia Fountain Society beginning in April 1869, whose fountains served people, horses, and dogs. Those Philadelphia fountains immediately proved their "utility and absolute necessity;" by September 1869 the Fountain Society had constructed 12, and the newly-founded Pennsylvania branch of the ASPCA had built another five. As of 1880, the Philadelphia Fountain Society alone maintained 50 fountains serving approximately 3 million people and 1 million horses and other animals.
The ASPCA had been founded in 1866 in New York, and spread quickly to active branches in Philadelphia and other cities. One of its concerns was the difficulty of finding fresh water for work horses in urban areas. Combination drinking fountains that provided a bubbler for people and a water trough for horses, and sometimes a lower basin for dogs, became popular. In particular, over 120 National Humane Alliance fountains were donated to communities across the United States between 1903 and 1913. The fountains were the gift of philanthropist Hermon Lee Ensign.
Also working in parallel were various organizations of the Temperance Movement, who advocated abstinence from alcohol, and saw providing free fresh water as an attractive alternative. furthering its cause. The Woman's Christian Temperance Union, founded in 1874, sponsored temperance fountains in towns and cities across the United States. The Sons of Temperance built an elaborate and popular drinking fountain for Philadelphia's 1876 Centennial Exposition, later moved close to Independence Hall, that dispensed ice water.
Henry D. Cogswell, a dentist and temperance crusader who made a fortune in San Francisco real estate, sponsored (and designed) dozens of artistic fountains, some of which were adorned with a statue of himself.
One myth claims that drinking fountains were first built in the United States in 1888 by the then-small Kohler Water Works (now Kohler Company) in Kohler, Wisconsin. However, no company by that name existed at the time.
Privately sponsored drinking fountains were often commissioned as works of art. Sculptors such as Karl Bitter, Alexander Stirling Calder, Gutzon Borglum and Daniel Chester French; and architects such as Paul Philippe Cret, Frederick Law Olmsted and Henry Hobson Richardson collaborated on them. These were frequently created as memorials to individuals, serving an ongoing utilitarian purpose as well as an artistic one.
In the United States, segregation of public facilities including but not limited to water fountains due to race, color, religion, or national origin was abolished by the Civil Rights Act of 1964. Prior to this, racially segregated water fountains with those for black people in worse condition than those for white people were common.
List of notable drinking fountains (organized by state)
''NOTE: some entries in this table overlap the entries in Drinking fountains in Philadelphia. Neither table is an exhaustive list.
See also
Drinking fountains in Philadelphia
History of fountains in the United States
References
.
Plumbing
Temperance movement | Drinking fountains in the United States | [
"Engineering"
] | 906 | [
"Construction",
"Plumbing"
] |
44,211,297 | https://en.wikipedia.org/wiki/Psilocybe%20medullosa | Psilocybe medullosa is a species of psychoactive mushroom. It was originally described in 1898 as Naucoria medullosa by Italian mycologist Giacomo Bresadola. Czech mycologist Jan Borovička transferred it to Psilocybe in 2007. A widespread but rather rare species, it is found in Europe, where it grows as a saprobe on woody debris and detritus. Chemical analysis has been used to confirm the presence of the psychedelic compounds psilocin and psilocybin in the fruit bodies but probably at low levels. Psilocybe silvatica is its American sister species; it differs by subtle changes in molecular markers (LSU, ITS rDNA, and others).
See also
List of Psilocybe species
List of psilocybin mushrooms
References
External links
Entheogens
Fungi described in 1898
Psychoactive fungi
medullosa
Psychedelic tryptamine carriers
Fungi of Europe
Taxa named by Giacomo Bresadola
Fungus species | Psilocybe medullosa | [
"Biology"
] | 202 | [
"Fungi",
"Fungus species"
] |
44,211,647 | https://en.wikipedia.org/wiki/Glass-filled%20polymer | Glass-filled polymer (or glass-filled plastic), is a mouldable composite material. It comprises short glass fibers in a matrix of a polymer material. It is used to manufacture a wide range of structural components by injection or compression moulding. It is an ideal glass alternative that offers flexibility in the part, chemical resistance, shatter resistance and overall better durability.
Materials
Either thermoplastic or thermosetting polymers may be used. One of the most widely used thermoplastics is a polyamide polymer nylon.
The first mouldable composite was Bakelite. This used wood flour fibres in phenolic resin as the thermoset polymer matrix. As the fibres were only short this material had relatively low bulk strength, but still improved surface hardness and good mouldability.
A wide range of polymers are now produced in glass-filled varieties, including polyamide (Nylon), acetal homopolymers and copolymers, polyester, polyphenylene oxide (PPO / Noryl), polycarbonate, polyethersulphone
Bulk moulding compound is a pre-mixed material of resin and fibres supplied for moulding. Some are thermoplastic or thermosetting, others are chemically cured and are mixed with a catalyst (polyester) or hardener (epoxy) before moulding.
Applications
Compared to the native polymer, glass-filled materials have improved mechanical properties of rigidity, strength and may also have improved surface hardness.
Compared to sheet materials
Bulk glass filled materials are considered distinct from fibreglass or fibre-reinforced plastic materials. These use a substrate of fabric sheets made from long fibres, draped to shape in a mould and then impregnated with resin. They are usually moulded into shapes made of large but thin sheets. Filled materials, in contrast, are used for applications that are thicker or of varying section and not usually as large as sheet materials.
References
Composite materials
Polymers
Fibre-reinforced polymers | Glass-filled polymer | [
"Physics",
"Chemistry",
"Materials_science",
"Engineering"
] | 420 | [
"Materials science stubs",
"Composite materials",
"Materials science",
"Materials",
"Polymer chemistry",
"Polymers",
"Matter"
] |
44,211,984 | https://en.wikipedia.org/wiki/Urine-diverting%20dry%20toilet | A urine-diverting dry toilet (UDDT) is a type of dry toilet with urine diversion that can be used to provide safe, affordable sanitation in a variety of contexts worldwide. The separate collection of feces and urine without any flush water has many advantages, such as odor-free operation and pathogen reduction by drying. While dried feces and urine harvested from UDDTs can be and routinely are used in agriculture (respectively, as a soil amendment and nutrient-rich fertilizer—this practice being known as reuse of excreta in agriculture), many UDDT installations do not apply any sort of recovery scheme. The UDDT is an example of a technology that can be used to achieve a sustainable sanitation system. This dry excreta management system (or "dry sanitation" system) is an alternative to pit latrines and flush toilets, especially where water is scarce, a connection to a sewer system and centralized wastewater treatment plant is not feasible or desired, fertilizer and soil conditioner are needed for agriculture, or groundwater pollution should be minimized.
There are several types of UDDTs: the single vault type which has only one feces vault; the double vault type which has two feces vaults that are used alternately; and the mobile or portable UDDTs, which are a variation of the single vault type and are commercially manufactured or homemade from simple materials. A UDDT can be configured as a sitting toilet (with a urine diversion pedestal or bench) or as a squatting toilet (with a urine diversion squatting pan). The most important design elements of the UDDT are: source separation of urine and feces; waterless operation; and ventilated vaults (also called "chambers") or removable containers for feces storage and treatment. If anal cleansing takes place with water (i.e., the users are "washers" rather than "wipers"), then this anal cleansing water must be drained separately and not be allowed to enter the feces vault.
Some type of dry cover material is usually added to the feces vault directly after each defecation event. The dry cover material may be ash, sawdust, soil, sand, dried leaves, mineral lime, compost, or dried and decomposed feces collected in a UDDT after prudent storage and treatment. The cover material serves to improve aesthetics, control flies, reduce odor and speed up the drying process.
Terminology
Alternative names for UDDTs include "urine diversion" for the "UD" part (instead of "urine-diverting") in connection with terms like "dehydration", "dry", "drying", "desiccation" (for the second "D") which gives quite a high number of possible mutations of the terms that UDDT can stand for. The "T" always stands for toilet. These variations in wording place different emphasis on the amount of drying that takes place in the feces vaults. Probably the most advanced drying takes place in UDDTs that feature two vaults or in UDDTs that have a built-in electrical fan. As a general overarching term the adjective "dry" is better than "dehydration" as it applies to a larger range of UDDT types.
UDDTs are often considered synonymous with "ecosan toilets" (ecological sanitation) or with composting toilets. However, neither of these associations is correct. The term ecosan is in fact much broader and not limited to this type of toilet. Not all UDDTs are used in conjunction with the practice of reusing excreta. There are also many other ecosan technologies that hygienically return nutrients to the food chain, such as subsurface artificial wetlands that produce fodder for cows. In addition, there is usually little composting taking place in the UDDT vaults (instead, it might be carried out in a secondary composting step which is external to the toilets).
Urine-diverting composting toilets are similar to UDDTs in that they also collect urine and feces separately. Treatment is achieved through the composting, a process quite different from pathogen removal by dehydration.
In Malawi, UDDTs are also called Skyloos.
Appropriateness
UDDTs are an interesting alternative for many special situations. For example when water is scarce, a low-cost solution is required or the soil conditions are such that it is difficult to dig pit latrines. Areas that are frequently flooded are another suitable application for UDDTs.
UDDTs can also be built for schools (many examples exist for example in Kenya, Rwanda and Uganda). However, these school UDDTs suffer from the same issues as any other type of school toilets: if clear responsibilities and a dedicated budget for the maintenance of school toilets is lacking, then the toilets may easily fall into disrepair, for example with blocked urine pipes or feces vaults that are not being emptied.
Design considerations
Fundamentals
Urine diversion takes advantage of the anatomy of the human body, which excretes urine and feces separately. In a UDDT, the urine is kept separate and drained via a basin with a small hole near the front of the toilet bowl or squatting pan, while feces fall through a larger drop-hole at the rear. This separate collection – or "source separation" – does not require the user to change positions between urinating and defecating, although some care is needed to ensure the right position over the user interface. Female users may find that some urine may enter the fecal vault during normal operation. This is typically a small amount and does not significantly affect the functioning of the toilet.
The urine separation function can also be achieved by designing the toilet bowl in such a way as to take advantage of the Coandă effect. In this design, users must direct their urine stream against the interior walls of the bowl (usually assisted by a sloping front section) so that it can be collected via a small trough that is recessed into the base of the bowl.
Designers and users of UDDTs should strive to keep the feces pile as dry as possible, as this is the most important factor in the prevention of odor and flies. During storage, the feces’ natural moisture slowly evaporates and exits via the vault's ventilation system, or is absorbed by the dry cover material. This process is called drying, dehydration or desiccation.
A UDDT consists of several functional elements. The main ones - which distinguish a UDDT from a pit latrine - are the urine diversion toilet seat or squatting pan, and one or two feces vaults (above ground).
Storage and drying time for feces in the vaults
The impact of the storage time on the dryness of the feces varies with climatic conditions. A general recommendation that is applicable for all climates is that "the storage duration for feces in double dehydration vaults should be at least six months, as measured from the last addition of fresh fecal matter to the vault".
During the dehydration process moisture is evaporating from the feces and microbes are degrading the organic material. It is the dry conditions together with the storage time itself that lead to the decline of pathogens in the feces. The goal of the dehydration process is to exceed the pathogens' desiccation tolerance (or dryness tolerance) and therefore to significantly reduce their numbers and viability, for example with respect to helminth eggs which are responsible for causing helminth infections in people in developing countries, particularly children.
Fresh feces consist of about 80% water and the majority of this water will evaporate away if it is allowed to do so by the feces not being enclosed in air-tight containers or vaults. The water content of dried feces after six months of drying is usually less than 25%. Depending on the degree of drying and the intended reuse application an additional post-treatment step, such as composting, might be necessary for reuse of excreta in agriculture.
Bench design
UDDTs can also be built with a bench style toilet seat. This design has been standardised by the company Rotaria del Peru who have built by now 800 double vault bench UDDTs in and around Lima, Peru. This type of toilet has a wide, spacious bench or box, covering both feces chambers, into which two urine diversion toilet seats are integrated.
Users with disabilities can benefit from this kind of design as it is very sturdy (compared to a pedestal-type toilet). The wide bench provides space for an assistant if needed, and handrails can easily be fixed to the walls next to the toilet. Most importantly, this type of UDDT is accessible directly from the ground level and does not require access steps or ramps which are common for many UDDT designs.
Accessibility
Superstructures associated with UDDTs are sometimes built with steep, narrow stairs and without handrails. This design is not recommended as it can prevent users with disabilities from accessing the toilet. The needs of people with disabilities should always be considered in the design of sanitation systems, and in the case of elevated structures less steep stairs or ramps should be used instead. The aforementioned "bench design" can alleviate the need for stairs.
If a squatting toilet is built, it is useful to add handle bars for people who need support while squatting. For people with disabilities who need physical support while squatting, particularly when cleaning afterwards, a portable seat can be placed on the squat toilet to allow people to sit. When not needed, it can be moved out of the way.
Designs for flood prone areas
In flood prone locations feces containers or vaults should be located above the flood water levels. If this is not feasible, it is possible to use ferrocement walls to isolate the vault(s) from encroaching flood waters.
Source of UDDT components
The toilet bowls or squatting pans for UDDTs can be commercially manufactured from plastic or ceramic. Alternatively, they can be fabricated locally from cement or other materials by residents, local companies, NGOs or contractors. Stand-alone UDDT toilets made of plastic with or without built-in electrical fans are also commercially available.
Waterless urinals
Waterless urinals are often installed alongside UDDTs for the convenience of male users. Urinals also reduce the risk that male users that are standing over the UDDT for urination (instead of sitting or squatting) inadvertently urinate into the feces vault or feces container. It is generally advisable that all UDDT users sit or squat to urinate. If urinals are provided, they can be used for those who prefer a standing position. Female urination devices are also available but they are not necessary for use with UDDTs as women normally sit or squat to urinate, a good posture which minimises urine from getting into the feces vault.
Sitting or squatting
UDDTs can be built as sitting or as squatting versions to accommodate the users' preference of defecation posture. Some people prefer squatting UDDTs in public places (thought to be more hygienic) but sitting UDDTs for households (thought to be more comfortable). It may be preferable to squat instead of sit for colon health, although this is not specific for UDDTs but may refer to any type of squat toilet.
Urban multi-storey buildings
UDDTs with combined ventilation and collection systems can also be installed in urban multi-storey buildings but only one successful example of such a design exists: the Gebers collective housing estate in Orhem, Sweden.
The use of UDDTs in urban settings of developed countries is still rare, as they come with some significant social, legal and technical challenges.
Example of Erdos Eco-Town Project, China
A much larger-scale installation which portrays the need to adhere to minimum design and installation standards existed in a project called the "Erdos Eco-Town Project" in Erdos located in the Inner Mongolia Autonomous Region of China. The project was implemented during 2003–2009. This urban installation for 3000 residents in multi-storey buildings utilized UDDTs that shared ventilation and urine collection pipework and made use of chutes that extended down into basements for the collection of feces. The UDDT system was accompanied by greywater treatment facilities, solid waste composting and the reuse of these materials as a fertilizer in agriculture.
However, due to several problems related to improper design and installation, the lack of a cohesive plan to address these deficiencies and the resulting resident objections, the UDDTs were replaced by conventional flush toilets in 2009. The main reasons for why these UDDTs were replaced with flush toilets were odor problems in the apartments as well as problems with the plumbing pipework for the urine pipes and the ventilation system. Another factor was that "water shortage (which had been a driver for dry toilets) was no longer regarded as a problem since a pipeline was built to the Yellow River and deeper fossil water resources were extracted".
Types
Single vault
UDDTs with a single vault have interchangeable containers to collect the fecal material. Depending on the size of the vault, two or more containers can be stored inside. Containers should be limited to a maximum volume of approximately 50 litres, so that they still can be manually moved when they fill up. Once a container is full, it can be left for further dehydration or removed for further treatment. Removal of the container requires care due to fresh, potentially pathogen-loaded feces being on top of the pile in the container. Because of the limited ventilation within a plastic bucket, such single-vault UDDTs may not reduce the pathogen load as effectively as double-vault UDDTs. Therefore, a post-treatment of the fecal material is usually required. This can be achieved through further dehydration, composting processes or heat treatments.
On the other hand, if the container is made from a material that has a high permeability with air, such as woven sacks or baskets, then the drying performance in single vault UDDTs may be similar to that of double vault UDDTs.
Double vault
Double-vault UDDTs are alternatively called twin-vault, two-vault or two-chambered UDDTs. In double-vault UDDTs, the fecal material dehydrates in situ. The two above-ground vaults are used alternately. While one vault is filling up, the other (full) one stores the fecal material under dry conditions for at least six months. During this resting period, no fresh feces are allowed to enter the full vault. In order to switch from one vault to the other, the user interface can either be switched or both vaults can be equipped with fixed seats and a cover sufficient to prevent access to the full vault. When the second vault becomes full and at least six months have passed, the first vault is emptied with a shovel and then the user interface is moved over accordingly. The vaults are commonly sized so that one vault fills up in six to twelve months.
Other (portable, mobile)
Other types of UDDTs exist which are essentially variations of the single-vault type, but which are more self-contained, sometimes referred to as portable, mobile or stand-alone units and identifiable by their one-piece molded plastic shells or, in the case of DIY versions, simple plywood box construction. Most users of self-contained UDDTs rely upon a post-treatment process to ensure pathogen reduction. This post-treatment may consist of long-term storage or addition to an existing or purpose-built compost pile or some combination thereof. A post-treatment step is unnecessary in the case of very modest seasonal use.
Mobile UDDTs are typically either fabricated of new materials in a factory or workshop using a mix of proprietary and off-the-shelf parts—and then sold to the public either directly or via distributors or retail outlets; or fabricated at home out of wood, using new and re-purposed parts and materials. They are typically compact and lightweight, allowing one person to easily lift, transport, and maneuver them into place. Likewise, installation is a relatively simple process given that everything needed for the proper functioning of the toilet, except a source of electrical power for those models that include a fan and some allowance for exterior ventilation, is contained within the molded or wooden carcass. One advantage of this type of UDDT is that they are portable, making them an interesting option for remote or temporary installations and for installations aboard moving vehicles or non-stationary residences such as boats, recreational-vehicles (i.e. caravan, camper van, motor home) and tiny-houses.
Features common to this type of UDDT include:
a smooth, easy-to-clean exterior surface
a molded seat with a cover (both or either sometimes fitted with a rubber or neoprene gasket to further assist in isolating the toilet's inner workings)
a molded urine diversion bowl (or bucket and funnel assembly) to facilitate the separate collection and storage in separate containers of urine and feces (the containers consisting of either a proprietary design or, in the case of DIY versions, readily-available or re-purposed buckets, bottles or jugs)
some allowance for either passive or active mechanical ventilation either consisting of a screened or filtered air inlet and a screened or filtered exhaust outlet (the latter consisting of a standard fitting to allow hook-up to a length of piping or tubing that is connected to the outdoors).
Features unique to some designs include:
cleats for fastening the toilet to the floor (particularly useful when the toilet is installed in a moving vehicle or non-stationary residence)
spill-proof urine storage to aid in leak-prevention during stormy weather or when otherwise underway (as in a moving boat or RV)
built-in agitator for mixing and aerating the contents of the feces container (which greatly aids in drying and odor prevention)
automatically or manually deployed pivoting or hinged trap door for covering the feces container when not in use.
Health aspects
During normal use, a UDDT is just as hygienic and safe to use as any other type of toilet. However, health aspects need to be considered during removal and emptying of the urine and feces containers of a UDDT. These health risks during emptying of the feces vault or container are significantly lower when compared to emptying the pit of pit latrines or the buckets of some types of dry toilets without urine diversion. However, the health risks are somewhat higher when compared to a flush toilet where the user does not have to carry out any emptying or maintenance tasks at the household level unless the flush toilet plugs, back-flows or otherwise experiences operating problems.
Compared to a flush toilet being flushed without closing its lid, a UDDT would have a lower risk of Clostridioides difficile spreading via aerosolization, as it does not involve turbulent water.
Regarding the health risks associated with reuse activities, the World Health Organization's guidelines' from 2006 titled "Guidelines for the safe use of wastewater, excreta and greywater in agriculture" explain the management of health risks associated with the use of excreta in agriculture. The key concept in these guidelines is the multiple barrier approach which can also be applied to reuse activities in connection with UDDTs.
Usage
Wiping materials
For wiping of the anal area after defecation—or for wiping after urination—UDDT users can avail themselves of the same materials that are utilized while using other types of toilets. Suitable biodegradable materials available in the surroundings can also be used, such as toilet paper, leaves, corn cobs or sticks. These materials are deposited along with feces in the feces portion of the toilet so that everything can eventually decompose together. For example, in Ecuador the soft, perfumed leaves of Piper auritum, Piperaceae and Melastomataceae are being used. Users have also used stones, although this makes the vault fill up very fast and is therefore not practical for UDDTs.
For portable UDDTs in particular, used toilet paper can alternatively be placed in a separate waste bin (for subsequent incineration, composting or disposal), as the addition of soiled toilet paper into the relatively small feces container could otherwise lead to it being filled rather quickly with mainly just toilet paper.
Anal cleansing with water
UDDTs can accommodate users who prefer anal cleansing with water rather than with toilet paper by utilising either a three-hole urine diversion squatting pan or an area and drain next to the urine diversion pedestal where washing can take place—away from the urine and feces holes. This is essential so as not to contaminate the urine and to keep the feces as dry as possible.
Due to the fecal content of anal cleansing water, it should be considered as blackwater and treated or disposed of accordingly. Anal cleansing water can be drained into a soak pit, planted mulch bed or an infiltration trench. The anal cleansing water should be discharged into coarse material below the ground, but well above the water table to avoid groundwater pollution.
Some UDDT designs are arranged such that the users do their anal cleansing with water above the urine compartment. This may be done for simplicity reasons, i.e. in order to avoid the need for a third hole and drain pipe for the anal cleansing water. This mixture of urine and anal cleansing water requires further treatment to remove pathogens before it can be safely utilized in agriculture.
Water for anal cleansing can be supplied via a hose or spigot fed by a pressurized water delivery system or a gravity fed system supplied by a rainwater tank located overhead or from a water bottle or jug that the user carries into the toilet cubicle.
Cover materials
For most UDDT types, users are encouraged to add a handful or scoopful of dry cover material directly after each defecation event. This cover material is added to promote dry conditions in the feces vault (by absorbing moisture), to control odor, to prevent infestation by flies and to create a visual barrier for the next user. It is also important to ensure that enough air can flow through the pile of drying feces. For this reason bulky or fibrous material that is dry and that decomposes slowly is recommended. A range of cover materials and combinations of these materials can be used, depending on what is readily available: Sawdust, rice hulls (suitable in areas where rice is grown), soil, wood ash (might not be available in sufficient volumes). Lime can also be used but is often more expensive than other options. Lime and wood ash both have the advantage of raising the pH value of the feces pile, thus adding to the pathogen killing abilities.
It can be beneficial to select the cover material carefully in order to not only cover the feces but also to inoculate them with beneficial soil microbes. In that case, finished compost could be used as cover material.
No cover materials added
In some circumstances and for reasons of simplicity, it can be sufficient to not use cover materials at all or to use toilet paper itself as cover material. One example is the case where the UDDT has a mechanized ventilation system and a view guard, like the UDDTs manufactured by Separett and Green Loo. Also in the case of public toilets, it can be easier to let the caretaker perform the task of adding cover material, rather than the user.
Resulting products
Dried feces
Further treatment
The required degree of treatment for the collected dried feces depends entirely on whether this product will be reused in agriculture. If it is not reused, but only buried, then no further treatment is required. The dried feces are in almost all cases not entirely sanitized when removed from a vault of the UDDT, so careful handling is obligatory. In scenarios wherein excreta is to be reused in agriculture, a secondary treatment of fecal matter and storage of urine is advisable to ensure adequate sanitization. Fecal material from single vault UDDTs must always be post-treated, even if just via prolonged storage. Fecal material from double vaults has typically passed a certain storage time and is therefore already more sanitized. However, a secondary form of treatment is optional but recommended for household systems and required for large-scale systems.
Secondary treatment can be performed at the community or household level and can include thermophilic composting where fecal material is composted at over 50 °C, prolonged storage with the duration of 1.5 to two years, chemical treatment with ammonia from urine to inactivate the pathogens, solar sanitation for further drying or heat treatment to eliminate pathogens. The most difficult pathogens to eliminate from the drying feces in the feces vaults are the helminth eggs which can cause helminth infections.
Reuse in agriculture or burial
Reuse of treated feces in agriculture—like reuse of excreta in agriculture in general—can result in increased crop production through fertilizing effects of nitrogen, phosphorus, potassium and improved soil fertility through organic carbon. If the dried feces are not reused in agriculture they can instead be buried at a minimum depth of 25 cm in which case they normally do not pose a public health risk.
Urine
Further treatment
The required degree of treatment for the collected urine depends entirely on whether this product will be reused in agriculture. If it is not reused, but only infiltrated, then no further treatment is required.
Urine that leaves the body of a healthy person is close to being sterile and requires much less treatment for pathogen removal than feces or fecal sludge. However, a contamination of urine with fecal pathogens is possible if the UDDT is not used correctly, i.e. when some fecal matter finds its way into the urine compartment. Also, for a few specific diseases, the relevant pathogens may be found in the urine; for example: Leptospira interrogans, Salmonella typhi, Salmonella paratyphi, Schistosoma haematobium, BK virus or Simian virus. The Ebola virus may also be found in urine from an infected person. The exact survival time of this particular virus in human urine outside of the human body is unclear but probably "up to several days" like with other body fluids at room temperature.
For these reasons, urine should always be treated for pathogen removal if it is going to be reused, unless reuse occurs at the same household where the urine was collected and on crops that are only consumed by these household members (in which case an infection among family members is more likely to occur via handshakes and hugs than via urine reuse activities).
The simplest and most common method of urine treatment for pathogen removal is via storage in closed vessels. The decomposition of urea that is present in urine into ammonia and hydrocarbonate leads to an increase in ammonia concentration and an increase of pH value to above 9. These two processes lead to pathogen reduction. Warm temperatures and low dilution of the urine with water increase pathogen removal.
Storage of urine kills bacterial pathogens encountered in urine – including Salmonella typhi and paratyphi and Mycobacterium tuberculosis'' – in a relatively short time span: a storage time of five weeks at temperatures below 20 °C or of two weeks at temperatures above 20 °C has been recommended to prevent transmission of mycobacteria when recycling human urine.
Recommended storage times to kill pathogens in urine vary from one to six months depending on ambient temperatures, the scale of the urine collection system and which crops will be fertilised with the urine.
Reuse in agriculture or infiltration
Reuse of treated urine in agriculture—like reuse of excreta in agriculture in general—can result in increased crop production through fertilizing effects of nitrogen, phosphorus, potassium and improved soil fertility through organic carbon. Urine from the UDDTs can safely be used as nitrogen-rich and phosphorus and potassium containing fertilizer after a recommended storage period for pathogen reduction (see above under "Further Treatment").
In cases where no reuse is possible or desired, urine is usually infiltrated in the soil unless this practice would cause groundwater pollution. In eThekwini municipality in South Africa or in Lima, Peru, for example, urine from UDDTs is safely infiltrated into the soil because the groundwater level is very low there and the groundwater is not used for any particular purpose. Infiltration can be done by directing the urine to a soak pit or by running a perforated urine pipe from the toilet to an area outside, where the hose is sloping gently downhill (for rural areas). Clogging of the pipe's holes can be avoided by ensuring there are no T-junctions, no joints and that a plastic mesh is installed in the urine funnel of the toilet to keep everything other than urine out.
Comparison
Pit latrines
Reasons for keeping urine and feces separate in a UDDT compared to a pit latrine can be to:
reduce odor (because mixing urine and feces together causes a lot of odor);
avoid production of wet, odorous fecal sludge, which has to be removed by someone when the pit latrine is full;
allow for the recovery of treated excreta so that it can be used as a fertilizer or soil enhancement.
The advantage of UDDTs compared to pit latrines is the conversion of feces into a dry odorless material and therefore an avoidance of the issues surrounding liquid fecal sludge management (e.g. odor, fly attraction, difficulties in pit emptying). A well-maintained UDDT is an odor and insect free toilet which is appreciated by users and allows simple removal and far less offensive and safer handling of the fecal material once the feces vault has filled up. Moreover, the risk of water pollution is minimised through the safe containment of feces in above-ground vaults and this allows the toilets to be constructed in locations where pit-based systems are not appropriate.
UDDTs with vaults are also more permanent structures than most pit latrines, the latter of which in rural areas are typically relocated when the pit is full rather than emptying the pit. Therefore, pit latrines need more space and people are less willing to invest in a higher quality super-structure as it will have to be dismantled and moved at some point.
In the experience of the non-governmental organisation WECF who introduced UDDTs in EECCA countries to people who had pit latrines, it was most successful converting people who were in regions lacking a reliable water supply and wastewater management. Since the introduction required behavior change in the recipients, WECF considered awareness raising and training by local partners to be important.
Sewer- and septic tank-based sanitation
The comparison of UDDTs with sewer-based sanitation systems (sewerage and wastewater treatment plants) is not as straightforward as the comparison with pit latrines as a sewer does not only deal with excreta management like a UDDT does, but it also transports greywater, municipal wastewater, stormwater and industrial wastewater. However, the installation of UDDTs in all households connected to a common sewer would result in vastly reduced volumes of water, nutrients and organic matter that arrive at the associated wastewater treatment plant.
Sewer-based excreta management is impractical in many regions due to limited water supplies and the high cost of sewer systems and wastewater treatment plants. Furthermore, water-based sanitation systems (flush toilets) dilute excreta and create vast wastewater streams, something that UDDTs do not.
Similarly, the comparison between UDDTs and septic tank-based sanitation systems is not as straightforward as the comparison with pit latrines as a septic system also treats greywater. However, the relatively high costs of septic systems, particularly mound-type septic systems can be partially mitigated or, if used in conjunction with an onsite greywater system, eliminated altogether by installing UDDTs in place of flush toilets.
Portable UDDTs offer the potential advantages of greater local control and quick deployment which is particularly useful when there is no capable centralized institutional infrastructure in place or no financial ability to implement larger centralized systems.
Pharmaceutical residues and other micropollutants
The separate, waterless collection and treatment of urine and feces in UDDTs prevents hormones, pharmaceutical residues and other micropollutants which are contained in human excreta from entering surface water or groundwater via treated sewage. This is because in conventional sewage treatment plants, these micropollutants are only partially removed and the remainder is discharged into surface water, possibly reaching the groundwater. Detected concentrations of pharmaceutical residues in groundwater were in the order of 50 ng/L in several locations in Germany.
Moreover, micropollutants can also become concentrated in sewage sludge. Following treatment, sewage sludge is either landfilled, incinerated, applied on agricultural land or, in some cases, retailed or given away for free to the general public. Each of these disposal options comes with myriad potential—and in some cases proven—hazards for human health and environment impacts of these chemicals. By not mixing human excreta with water and the other contaminants that are disposed of in sewers and septic tanks, UDDTs avoid many of the problems associated with these practices.
If the excreta collected from UDDTs is treated further and buried or used as agricultural or horticultural fertilizer then the pharmaceutical residues in the excreta will be degraded better in terrestrial systems (soil) than in aquatic systems. Therefore, UDDTs (or in fact all urine diversion systems) have an advantage over sewer-based sanitation systems with respect to these problem of micro-pollutants.
Challenges
Operational issues
There are several operational problems that can happen with UDDTs. The main ones are: Urine may accumulate in the urine diversion section of the toilet due to blockages in the urine pipe; odor coming from the feces vault because the contents of the feces vault have become too wet. In this case also flies, other insects or rodents may appear in the feces vault.
If there is insufficient commitment, user preparation, follow-up and support, such operational problems can lead to failure of UDDT pilot projects.
Costs
UDDTs are sometimes considered too expensive compared to pit latrines, but this criticism does not include the cost of emptying pits and the potential value of fertilizers that can be recycled via UDDTs should the users wish to do so (noting that most UDDT installations worldwide currently do not reuse excreta in agriculture). Rather than looking only at construction costs, long-term operational costs and benefits should also be considered, especially since the regular emptying or re-building of pit latrines may be a significant expense. When a period of for example 10 years is considered, UDDTs may well be the more economical alternative, since the emptying of feces vaults is simple and safer, thus less expensive, even if users decide to enter into a contract with someone else to do this.
Compared to flush toilets connected to sewer systems and wastewater treatment plants, UDDTs are usually less expensive. However, to enable accurate comparisons of costs, this needs to be assessed on a case-by-case basis because the sewer system and treatment plant also transports and treats greywater whereas the UDDT does not. This means that the two systems provide a different level of service to the user. An example calculation for such a cost comparison exists for the case of Lima, Peru.
There is even a minimalist UDDT model that costs essentially nothing to construct and which only requires salvaging and assembling selected plastic items from the garbage and which can be implemented by the poorest people, disaster victims, and those who want to gain experience with UDDTs.
History
The UDDTs with two dehydration vaults that are known today were originally designed around 1950 in Japan and further developed in Vietnam in the 1960s as a means of increasing the hygienic safety of excreta reused in agriculture. This means their development was originally closely linked to the ecosan (ecological sanitation) approach to optimizing resource recovery of nutrients and organic matter in agriculture. Beginning in the early part of the 2000s, UDDTs have been seen increasingly as a toilet type that can provide advantages even without any reuse activities attached to it.
Since the 1990s, modifications of this design (such as the addition of ventilation piping to the feces vault) have been developed in many countries. Prefabricated ceramic or plastic urine diversion squatting pans and pedestals have become available on the market, generally increasing the durability and perceived prestige associated with the system.
UDDTs have also been commercially produced in Sweden since the mid-1990s. For example, between 1994 and 2010 the Separett company sold approximately 200,000 UDDTs. Numerous off-the shelf commercial products are now available and are used in locations where a connection to a sanitary sewer system is not possible, permitted or desired such as in remote summer cottages or for camping activities. At all times, users have also been building their own low-cost UDDTs with simple materials such as a funnel connected to a hose, a bucket and a seat.
Examples
South Africa (eThekwini Municipality, Durban)
The highest number of UDDTs in one area have been installed by the eThekwini Municipality in the non-sewered peri-urban areas of Durban, South Africa. To date, about 80,000 UDDTs are in operation in that area, serving about 500,000 residents (reuse of urine or excreta is currently not taking place).
Haiti
The NGO SOIL in Haiti began building UDDTs and composting plants in Port-au-Prince as part of the 2010 Haiti earthquake emergency relief effort in northern Haiti. They have since branched out into providing toilets for residential use, this being their primary goal moving forward as they transition their focus from emergency relief to providing sustainable and ecological sanitation for paying customers. Their current dry toilet design for households includes a small portable single vault unit made out of wood that is either fitted with a single container for combined excreta collection or with a urine diversion insert, with 80% of these installations currently being of the UDDT type. As of 2014, SOIL has transformed all of their public UDDT vault toilets to an open vault design with removable plastic drums for feces collection. This improves the processes by which feces is collected and transported to their waste treatment facility, making their business now a fully "container-based system". This allows SOIL to respond to heavy use (since their toilets were filling up too quickly) and ensures a safe final product for reuse. In most cases, these UDDTs utilize soak pits (normally located directly beneath the toilet superstructure) for onsite disposal of urine.
SOIL continues to provide humanitarian relief in some of Haiti's most vulnerable communities – notably those that have been particularly impacted by the cholera epidemic – by providing free access to public container-based UDDTs for over 3,500 people. In addition, over 2,000 people are currently accessing a SOIL "EcoSan toilet" through the "EkoLakay" business pilot, with a growing waitlist of people wanting to join, thus demonstrating the market demand for affordable sanitation, even in the world's most economically impoverished communities.
Since building the first waste treatment facility in Haiti in 2009, SOIL has become one of the largest waste treatment operations in the country. SOIL's two composting waste treatment facilities currently transform over 20,000 gallons (75,708 liters) of human waste into safe, organic, agricultural-grade compost every month. The compost produced at these facilities is sold to farmers, organizations, businesses, and institutions around the country to help finance SOIL's waste treatment operations.
Ecuador
Hundreds of UDDTs have been built in Ecuador to date. The various models in use adapt to different preferences, budgets and conditions, and the need to sometimes transport materials to remote locations by small airplanes.
Many of these UDDTs serve indigenous communities who live along small rivers as well as ecotourism operations in the Amazonian part of the country. In these regions, piped water supply is often lacking, clay-rich soils do not permit infiltration of wastewater, and the groundwater level is usually high. These factors make other types of toilets or other forms of excreta management problematic. For example, local governments and ecotourism operations often install flush toilets that drain straight into rivers or into holes in the ground, where the water is intended to drain but cannot, since the soil is mostly impermeable clay. Coupled with the abundant local rainfall, these pits tend to fill very fast and overflow into the nearest streams. The streams get easily contaminated with fecal matter, as they are often quite small and there is not much dilution with clean river water. This leads to health hazards for the communities who use these rivers for drinking water, washing, swimming, and fishing.
Namibia
In Namibia a type of UDDT was developed which is locally called the "Otji toilet". This UDDT also uses the Coandă effect to divert the majority of the urine into a trough at the base of the pedestal and from there into an infiltration area. Between 2003 and 2011 about 1,200 Otji toilets have been installed in the south of Namibia and the rural areas around the Otjiwarongo District. Using the same design, the NGO EcoSur has built "Otji style" UDDTs in Ecuador and El Salvador since 2007, where they are called "Inodoro Seco".
Other countries
The NGO Women in Europe for a Common Future (WECF) and local partners have built urine-diverting dry toilets for schools in Eastern Europe, Caucasus and Central Asia (EECCA region) in areas that lack a reliable water supply and waste management.
In El Alto, Bolivia the NGO Fundación Sumaj Huasi has constructed nearly 1000 UDDTs for 4500 persons, and is carrying out communal composting for the excreta collected.
Boating, recreational vehicles and camping
A UDDT is an alternative to conventional toilets that store waste in blackwater tanks. Some such are marketed under the brand names "C-Head", "Compo Closet" "BoonJon", "Nature's Head" and "Air Head". Leave no trace is not only a philosophy but also a necessity in areas where human waste left behind will not decay naturally. Some models of UDDTs allow feces to be collected and packed out, leaving behind only the nearly pathogen-free urine.
Society and culture
General hurdles for acceptance
There are several barriers to a wider acceptance of this technology: the technology is not well known yet, buying UDDT components can be difficult, and in general it is difficult to finance sanitation services for the urban poor who rely on on-site sanitation. Existing, affordable piped water supply and sanitary sewer infrastructure may also be an impediment to widespread adoption of UDDTs, as their existence not only removes two of the main drivers for UDDTs but also represents a significant public investment.
Many users do not have an interest in handling their excreta, which can be another hurdle for acceptance of UDDTs. Provisions can be made to offer door-to-door/curbside collection of these materials, similar to how existing municipal or private schemes collect household organic waste (from kitchens and gardens, etc.) and transport these materials to a centralized facility for composting or biogas generation.
Number of users
The exact number of people using UDDTs worldwide is unknown, but a rough estimate by GIZ (German Development Cooperation) in 2012 based on known projects in 84 countries put the number at approximately 2 million people.
Regulations
Regulatory aspects in the U.S.
Use of dried feces
The International Association of Plumbing and Mechanical Officials (IAPMO), a plumbing and mechanical code structure currently utilized by many western states, has recently proposed an addition to its "Green Plumbing Mechanical Code Supplement" that "outlines performance criteria for site built composting toilets with and without urine diversion and manufactured composting toilets". If adopted, this new far reaching composting and urine diversion toilet code (the first of its kind in the United States) will appear in the 2015 edition of the Green Supplement to the Uniform Plumbing Code.
Several U.S. states currently permit disposal of feces from UDDTs or composting toilets (usually a clear distinction between different types of dry toilets is not made) by burial with some mandating lesser minimum depths, as little as 6 inches, and others not specifying any minimum depth at all. For instance:
The Commonwealth of Massachusetts requires that "residuals from the [composting toilet] system must be buried on-site and covered with a minimum of six inches of clean compacted soil".
In Oregon the applicable regulations state that "humus from composting toilets may be used around ornamental shrubs, flowers, trees, or fruit trees and shall be buried under at least twelve inches of soil cover".
Rhode Island acknowledges that "solids produced by alternative toilets may be buried on site", but specifies that "residuals shall not be applied to food crops".
The Department of Health of the Commonwealth of Virginia requires that "all materials removed from a composting privy shall be buried", and that "compost material shall not be placed in vegetable gardens or on the ground surface".
The State of Vermont permits users to dispose of the byproducts via "shallow burial in a location approved by the Agency that meets the minimum site conditions [required of an onsite septic tank-based sanitation system]".
The State of Washington takes a wholly different tack in choosing to model its extensive regulations that oversee the use of dry toilets (what it refers to as "waterless toilets") in large part on the federal regulations that govern sewage sludge.
For dry toilet users in the United States (which includes users of UDDTs), an important distinction to keep in mind—and one that is supported by the aforementioned existence of numerous state regulations which make no mention of, and also diverge widely from, the requirements of the federal regulations that govern the management of sewage sludge—is that as long as the excreta in question is not ever referred to as "fertilizer" (but instead simply a material that is being disposed of) the federal 503 rule, known colloquially as the "EPA Biosolids Rule" or the "EPA Sludge Rule", has no jurisdiction over the byproducts of a dry toilet and that all oversight of these materials falls to the individual states.
Use of urine
At present reuse of urine as a fertilizer in the United States is still in the conceptual phase. Studies into its feasibility are currently underway in Brattleboro, Vermont, and are being conducted by the not-for-profit Rich Earth Institute. Perhaps accordingly, a quick review of the pertinent regulations in existence in several different states turns up zero mentions of "urine diversion" and zero mentions of urine specifically as a standalone material which requires distinct oversight. Instead, when it is mentioned, it is always in conjunction with feces (as in the contents of a composting toilet or other non-source-separating dry toilet type. At least one state specifically regulates "liquids" produced but not recycled by a composting toilet (which could be construed as referring to urine) but the fact remains that none of the states surveyed distinctly uses the word "urine" when referring to "liquids". It is expected that as urine diverting toilets grow in popularity states will respond by amending their existing regulations to account for urine diverting toilets and also urine as a separate and distinct waste or resource stream.
Moreover, plans are currently underway to finalize a uniform plumbing code that would "represent the first codified requirements for the safe installation, maintenance and use for [composting and urine diversion toilets] in any installation".
Gallery
See also
Arborloo
Container-based sanitation
Peak phosphorus
Portable toilet
Sanitation
References
External links
Documents on UDDTs in library of the Sustainable Sanitation Alliance
UDDT photos in flickr photo database of the Sustainable Sanitation Alliance
Technical drawings of UDDTs
Toilet types
Toilets
Sanitation | Urine-diverting dry toilet | [
"Biology"
] | 9,950 | [
"Excretion",
"Toilets"
] |
44,212,121 | https://en.wikipedia.org/wiki/Fluxapyroxad | Fluxapyroxad is a broad-spectrum pyrazole-carboxamide fungicide used on a large variety of commercial crops. It stunts fungus growth by inhibiting the succinate dehydrogenase (SQR) enzyme. Application of fluxapyroxad helps prevent many wilts and other fungal infections from taking hold. As with other systemic pesticides that have a long chemical half-life, there are concerns about keeping fluxapyroxad out of the groundwater, especially when combined with pyraclostrobin. There is also concern that some fungi may develop resistance to fluxapyroxad.
Chemical structure
The compound is an amide of 3-(difluoromethyl)-1-methyl-1H-pyrazole-4-carboxylic acid combined with an aniline having an ortho-substituted triflurorobenzene group.
Biological action
Fluxapyroxad is a succinate dehydrogenase inhibitor (SDHI). It interferes with a number of key fungal life functions, including spore germination, germ tube growth, appresoria formation and mycelium growth. Specifically it interferes with the production of succinate dehydrogenase, the complex II in the mitochondrial respiration chain, which in turn interferes with the tricarboxylic cycle and mitochondrial electron transport.
Crops
Fluxapyroxad is commonly used as a fungicide for grains, row crops, vegetable crops, and fruit trees (pome and prunus), including:
Fungal diseases
Fluxapyroxad provides protection against many fungal diseases. Studies have shown specific efficacy against diseases such as black point, Botrytis gray mold, early blight, and powdery mildew; however, fluxapyroxad was found to have no efficacy against anthracnose on lentils.
Toxicity
Fluxapyroxad has a low toxicity for humans, slightly toxic after a single ingestion, and relatively non-toxic after single inhalation or topical skin contact. However, fluxapyroxad is highly toxic to fish, fresh-water and salt-water invertebrates, and to aquatic plants, as well as being toxic to small mammals. The primary target organ for fluxapyroxad exposure is the liver. As the dose or duration of exposure to fluxapyroxad increased, clinical chemistry changes related to liver function also occurred, followed by hepatocellular necrosis, neoplastic changes in the liver, and tumors. Fluxapyroxad was found "not likely" to be carcinogenic in humans and there was no evidence of neurotoxicity.
The United States Environmental Protection Agency has established tolerance amounts that are allowed to be present on consumer food. These range from 0.05 ppm on almonds and pecans to 3.0 ppm on leafy brassica, and 15 ppm on other leafy vegetables. The EPA is currently considering reducing those tolerances.
Registration and approval
Fluxapyroxad has been approved for use as a fungicide in the United States, Canada and the European Union. In the spring of 2012, fluxapyroxad, trademarked under the names Sercadis, Imbrex and Xemium and manufactured by BASF Corporation, was registered for use as a fungicide in the United States. Fluxapyroxad is also one of the two active ingredients in Priaxor fungicide and Merivon fungicide, the other active ingredient being a strobilurin called pyraclostrobin.
References
Fungicides
Carboxamides
Pyrazoles
Fluoroarenes
Biphenyls | Fluxapyroxad | [
"Biology"
] | 764 | [
"Fungicides",
"Biocides"
] |
44,213,513 | https://en.wikipedia.org/wiki/Rhytisma%20punctatum | Rhytisma punctatum is a species of fungus in the family Rhytismataceae. The fungus causes speckled tar spot of maple leaves. The small spots are black, raised from the leaf surface, and occur in dense groups on the upper surface. Areas afflicted by the fungus will retain their color even after the remainder of the leaf has faded.
References
External links
Fungi described in 1800
Fungal plant pathogens and diseases
Leotiomycetes
Taxa named by Christiaan Hendrik Persoon
Fungus species | Rhytisma punctatum | [
"Biology"
] | 107 | [
"Fungi",
"Fungus species"
] |
44,215,055 | https://en.wikipedia.org/wiki/Wildlife%20of%20South%20Asia | The wildlife of South Asia encompasses that of India, Pakistan, Nepal, Bhutan, Bangladesh, Sri Lanka, Afghanistan and the Maldives.
Wildlife of India
Wildlife of Pakistan
Wildlife of Nepal
Wildlife of Bhutan
Wildlife of Bangladesh
Wildlife of Sri Lanka
Wildlife of Maldives
Wildlife of Afghanistan
Wildlife conservation
Fauna of India
Flora of India
List of fish in India
Ecoregions of India
The study of natural history in India
Asiatic Lion Reintroduction Project
List of Zoos in India
Central Zoo Authority of India (CZA)
Zoo Outreach Organisation (ZOO), India is an NGO
Wildlife Institute of India (WII)
Indian Institute of Forest Management (IIFM)
Zoological Survey of India (ZSI)
India Nature Watch (INW) spreading the love of nature and wildlife in India through photography
Geological Survey of India (GSI) also maintains 2 fossil parks currently.
Fossil Parks of India
Protected areas of India
List of protected areas in India
National parks of India
Biosphere reserves of India
Conservation areas of India
Wildlife sanctuaries of India
Reserved forests and protected forests of India
Conservation reserves and community reserves of India
Communal forests of India, including
Sacred groves of India
Social forestry in India
Private protected areas of India
Environmental policy of India
Indian Forest Act, 1927
Wildlife Protection Act of 1972
Project Tiger
Project Elephant
Ministry of Environment and Forests (India) | Wildlife of South Asia | [
"Biology"
] | 259 | [
"Biota by country",
"Biota of India",
"Biota of Pakistan"
] |
44,215,351 | https://en.wikipedia.org/wiki/Committee%20room | As well as simply referring to any room in which a committee meets, 'Committee Room' is a term used in connection with UK elections to describe the place or places where a political party organizes its campaign. It most usually refers to a room, often in a private house, which is actually used on the day of the election itself, rather than the run up to the election. Typical activities will involve collating lists of supporters and attempting to track whether or not they have actually voted in the election as well as organizing transport to the Polling station.
If a committee room is rented (as opposed to the more normal position of being in a supporter's own home) then the costs are an election expense. Section 108 of The Representation of the People Act 1983. originally made it illegal to hold committee rooms in pubs and other licensed premises, but this restriction was removed by the Political Parties, Elections and Referendums Act 2000
References
Rooms
Committees | Committee room | [
"Engineering"
] | 188 | [
"Rooms",
"Architecture"
] |
44,216,842 | https://en.wikipedia.org/wiki/Magnetic%20resonance%20%28quantum%20mechanics%29 | In quantum mechanics, magnetic resonance is a resonant effect that can appear when a magnetic dipole is exposed to a static magnetic field and perturbed with another, oscillating electromagnetic field. Due to the static field, the dipole can assume a number of discrete energy eigenstates, depending on the value of its angular momentum (azimuthal) quantum number. The oscillating field can then make the dipole transit between its energy states with a certain probability and at a certain rate. The overall transition probability will depend on the field's frequency and the rate will depend on its amplitude. When the frequency of that field leads to the maximum possible transition probability between two states, a magnetic resonance has been achieved. In that case, the energy of the photons composing the oscillating field matches the energy difference between said states. If the dipole is tickled with a field oscillating far from resonance, it is unlikely to transition. That is analogous to other resonant effects, such as with the forced harmonic oscillator. The periodic transition between the different states is called Rabi cycle and the rate at which that happens is called Rabi frequency. The Rabi frequency should not be confused with the field's own frequency. Since many atomic nuclei species can behave as a magnetic dipole, this resonance technique is the basis of nuclear magnetic resonance, including nuclear magnetic resonance imaging and nuclear magnetic resonance spectroscopy.
Quantum mechanical explanation
As a magnetic dipole, using a spin system such as a proton; according to the quantum mechanical state of the system, denoted by , evolved by the action of a unitary operator ; the result obeys Schrödinger equation:
States with definite energy evolve in time with phase , () where E is the energy of the state, since the probability of finding the system in state = is independent of time. Such states are termed stationary states, so if a system is prepared in a stationary state, (i.e. one of the eigenstates of the Hamiltonian operator), then P(t) = 1, i.e. it remains in that state indefinitely. This is the case only for isolated systems. When a system in a stationary state is perturbed, its state changes, so it is no longer an eigenstate of the system's complete Hamiltonian. This same phenomenon happens in magnetic resonance for a spin system in a magnetic field.
The Hamiltonian for a magnetic dipole (associated with a spin particle) in a magnetic field is:
Here is the Larmor precession frequency of the dipole for magnetic field and is z Pauli matrix. So the eigenvalues of are and . If the system is perturbed by a weak magnetic field , rotating counterclockwise in x-y plane (normal to ) with angular frequency , so that , then and are not eigenstates of the Hamiltonian, which is modified into
It is inconvenient to deal with a time-dependent hamiltonian. To make time-independent requires a new reference frame rotating with , i.e. rotation operator on , which amounts to basis change in Hilbert space. Using this on Schrödinger's equation, the Hamiltonian becomes:
Writing in the basis of as-
Using this form of the Hamiltonian a new basis is found:
where and
This Hamiltonian is exactly similar to that of a two state system with unperturbed energies and with a perturbation expressed by ; According to Rabi oscillation, starting with state, a dipole in parallel to with energy , the probability that it will transit to state (i.e. it will flip) is
Now consider , i.e. the field oscillates at the same rate the dipole exposed to the field does. That is a case of resonance. Then at specific points in time, namely , the dipole will flip, going to the other energy eigenstate with a 100% probability. When , the probability of change of energy state is small. Therefore, the resonance condition can be used, for instance, to measure the magnetic moment of a dipole or the magnetic field at a point in space.
A special case to show applications
A special case occurs where a system oscillates between two unstable levels that have the same life time . If atoms are excited at a constant, say n/time, to the first state, some decay and the rest have a probability to transition to the second state, so in the time interval between t and (t + dt) the number of atoms that jump to the second state from the first is , so at time t the number of atoms in the second state is
=
The rate of decay from state two depends on the number of atoms that were collected in that state from all previous intervals, so the number of atoms in state 2 is ; The rate of decay of atoms from state two is proportional to the number of atoms present in that state, while the constant of proportionality is decay constant . Performing the integration rate of decay of atoms from state two is obtained as:
From this expression many interesting points can be exploited, such
Varying uniform magnetic field so that in produces a Lorentz curve (see Cauchy–Lorentz distribution), detecting the peak of that curve, the abscissa of it gives , so now (angular frequency of rotation of = , so from the known value of and , the gyromagnetic ratio of the dipole can be measured; by this method we can measure Nuclear spin where all electronic spins are balanced. Correct measurement of nuclear magnetic moment helps to understand the character of nuclear force.
If is known, by varying , the value of can be obtained. This measurement technique is precise enough for use in sensitive magnetometers. Using this technique, the value of magnetic field acting at a particular lattice site by its environment inside a crystal can be obtained.
By measuring half-width of the curve, d = , for several values of (i.e. of ), we can plot d vs , and by extrapolating this line for , the lifetime of unstable states can be obtained from the intercept.
Rabi's method
The existence of spin angular momentum of electrons was discovered experimentally by the Stern–Gerlach experiment. In that study a beam of neutral atoms with one electron in the valence shell, carrying no orbital momentum (from the viewpoint of quantum mechanics) was passed through an inhomogeneous magnetic field. This process was not approximate due to the small deflection angle, resulting in considerable uncertainty in the measured value of the split beam.
Rabi's method was an improvement over Stern-Gerlach. As shown in the figure, the source emits a beam of neutral atoms, having spin angular momentum . The beam passes through a series of three aligned magnets. Magnet 1 produces an inhomogeneous magnetic field with a high gradient (as in Stern–Gerlach), so the atoms having 'upward' spin (with ) will deviate downward (path 1), i.e. to the region of less magnetic field B, to minimize energy. Atoms with 'downward' spin with ) will deviate upward similarly (path 2). Beams are passed through slit 1, to reduce any effects of source beyond. Magnet 2 produces only a uniform magnetic field in the vertical direction applying no force on the atomic beam, and magnet 3 is actually inverted magnet 1. In the region between the poles of magnet 3, atoms having 'upward' spin get upward push and atoms having 'downward' spin feel downward push, so their path remains 1 and 2 respectively. These beams pass through a second slit S2, and arrive at detector and get detected.
If a horizontal rotating field , angular frequency of rotation is applied in the region between poles of magnet 2, produced by oscillating current in circular coils then there is a probability for the atoms passing through there from one spin state to another ( and vice versa), when = , Larmor frequency of precession of magnetic moment in B. The atoms that transition from 'upward' to 'downward' spin will experience a downward force while passing through magnet 3, and will follow path 1'. Similarly, atoms that change from 'downward' to 'upward' spin will follow path 2', and these atoms will not reach the detector, causing a minimum in detector count. If angular frequency of is varied continuously, then a minimum in detector current will be obtained (when = ). From this known value of (, where g is 'Landé g factor'), 'Landé g-factor' is obtained which will enable one to have correct value of magnetic moment . This experiment, performed by Isidor Isaac Rabi is more sensitive and accurate compared than Stern-Gerlach.
Correspondence between classical and quantum mechanical explanations
Spin angular momentum allows magnetic resonance phenomena to be explained via classical physics. When viewed from the reference frame attached to the rotating field, it seems that the magnetic dipole precesses around a net magnetic field , where is the unit vector along uniform magnetic field and is the same in the direction of rotating field and .
{| class="toccolours collapsible collapsed" style="text-align:left" width="60%"
!Proof of classical expression for precession
|-
|
Classical electrodynamics tells us that torque on a magnetic dipole of moment is , so its equation of motion is , (where is the angular momentum associated with dipole) so –
For the case under consideration the dipole is under the action of magnetic field and , hence
It is easier to solve it by transforming co-ordinate system to OXYZ in which becomes OX axis, in that frame –
here Using and , one can see that –
so, here effective field becomes :
|}
So when , a high precession amplitude allows the magnetic moment to be completely flipped. Classical and quantum mechanical predictions correspond well, which can be viewed as an example of the Bohr Correspondence principle, which states that quantum mechanical phenomena, when predicted in classical regime, should match the classical result. The origin of this correspondence is that the evolution of the expected value of magnetic moment is identical to that obtained by classical reasoning. The expectation value of the magnetic moment is . The time evolution of is given by
so,
So, and
which looks exactly similar to the equation of motion of magnetic moment in classical mechanics –
This analogy in the mathematical equation for the evolution of magnetic moment and its expectation value facilitates to understand the phenomena without a background of quantum mechanics.
Magnetic resonance imaging
In magnetic resonance imaging (MRI) the spin angular momentum of the proton is used. The most available source for protons in the human body is represented by hydrogen atoms in water. A strong magnetic field applied to water causes the appearance of two different energy levels for spin angular momentum, and , using .
According to the Boltzmann distribution, as the number of systems having energy out of at temperature is (where is the Boltzmann constant), the lower energy level, associated with spin , is more populated than the other. In the presence of a rotating magnetic field more protons flip from to than the other way, causing absorption of microwave or radio-wave radiation (from the rotating field). When the field is withdrawn, protons tend to re-equilibrate along the Boltzmann distribution, so some of them transition from higher energy levels to lower ones, emitting microwave or radio-wave radiation at specific frequencies.
Instead of nuclear spin, spin angular momentum of unpaired electrons is used in EPR (electron paramagnetic resonance) in order to detect free radicals, etc.
Magnetic resonance as a quantum phenomenon
The phenomenon of magnetic resonance is rooted in the existence of spin angular momentum of a quantum system and its specific orientation with respect to an applied magnetic field. Both cases have no explanation in the classical approach and can be understood only by using quantum mechanics. Some people claim that purely quantum phenomena are those that cannot be explained by the classical approach. For example, phenomena in the microscopic domain that can to some extent be described by classical analogy are not really quantum phenomena. Since the basic elements of magnetic resonance have no classical origin, although analogy can be made with classical Larmor precession, MR should be treated as a quantum phenomenon.
See also
Nuclear magnetic resonance
Magnetic resonance imaging
Bloch equations
Physics of magnetic resonance imaging
References
Quantum mechanics
Magnetism | Magnetic resonance (quantum mechanics) | [
"Physics"
] | 2,551 | [
"Theoretical physics",
"Quantum mechanics"
] |
44,217,023 | https://en.wikipedia.org/wiki/Marie%20Kondo | , also known as , is a Japanese organizing consultant, author, and TV presenter.
Kondo has written four books on organizing, which have collectively sold millions of copies around the world. Her books have been translated from Japanese into several languages, and her book The Life-Changing Magic of Tidying Up (2011) has been published in more than 30 countries. It was a best-seller in Japan and in Europe, and was published in the United States in 2014.
In 2015 she was named to the TIME 100 list of the world's most influential people.
In the United States and the United Kingdom, the profile of Kondo and her methods were greatly promoted by the success of the Netflix series Tidying Up with Marie Kondo, released in 2019, which gained Kondo a nomination for the Primetime Emmy Award for Outstanding Host for a Reality or Competition Program. Kondo opened an online store called KonMari the same year. In August 2021, Netflix released a follow-up show, Sparking Joy with Marie Kondo.
Life
Early life
Kondo was born on 9 October 1984 in Osaka, Japan. She has an older brother and a younger sister.
Kondo claims her study of neatness began at age 5, when feng shui became trendy in Tokyo, Japan; its Japanese equivalent was called fusui. Her mother "was applying the method, but to [Kondo's] eye, the house was not tidy enough to have the feng shui effect". As a result, Kondo began implementing the "tidying up" process at this age to help her mother's efforts.
Education and early career
Kondo attended the Chūō Ward Hisamatsu Elementary School.
Afterwards, she attended private Quaker school Friends Girls Junior & Senior High School in Mita, Minato, Tokyo.
In junior school, Kondo ran into the classroom to tidy up bookshelves while her classmates were playing in physical education class. Whenever there were nominations for class roles, she did not seek to be the class representative or the pet feeder. Instead, she yearned to be the bookshelf manager to continue tidying up books. She said she experienced a breakthrough in organizing one day: "I was obsessed with what I could throw away. One day, I had a kind of nervous breakdown and fainted. I was unconscious for two hours. When I came to, I heard a mysterious voice, like some god of tidying telling me to look at my things more closely. And I realized my mistake: I was only looking for things to throw out. What I should be doing is finding the things I want to keep. Identifying the things that make you happy: that is the work of tidying."
She founded her organising consulting business when she was 19 and a sociology student at Tokyo Woman's Christian University. In her senior year, she wrote her capstone thesis, titled "Tidying up as seen from the perspective of gender".
She spent five years as an attendant maiden at a Shinto shrine.
KonMari method
Kondo's method of organizing is known as the KonMari method, and consists of gathering together all of one's belongings, one category at a time, and then keeping only those things that "spark joy" (Japanese language ときめく tokimeku, translated as equivalent to English "flutter, throb, palpitate"), and choosing a place for everything from then on. Kondo advises to start the process of tidying up by "quickly and completely" discarding whatever it is in the house that doesn't spark joy. Following this philosophy will acknowledge the usefulness of each belonging and help owners learn more about themselves, which will help them be able to more easily decide what to keep or discard. She advises to do this by category of items and not their location in the house. For example, all the clothes in the house should be piled up first, assessed for tokimeku, and discarded if not needed, followed by other categories such as books, papers, miscellany, and mementos. Another crucial aspect of the KonMari method is to find a designated place for each item in the house and making sure it stays there.
Kondo says that her method is partly inspired by the Shinto religion. Cleaning and organizing things properly can be a spiritual practice in Shintoism, which is concerned with the energy or divine spirit of things (kami) and the right way to live (kannagara): Treasuring what you have; treating the objects you own as not disposable, but valuable, no matter their actual monetary worth; and creating displays so you can value each individual object are all essentially Shinto ways of living.
Media appearances
A two-part TV dramatisation was filmed in 2013 based on Kondo and her work, titled (). She has lectured and made television appearances. She released a series of videos teaching "the best way to fold for perfect appearance".
On 1 January 2019, Netflix released a series called Tidying Up with Marie Kondo. In the series, Kondo visits various American family homes full of clutter and guides the families in tidying up their houses through her KonMari method. Following the release of her Netflix series, Kondo was the subject of various Internet memes. A clip of her saying "I love mess" included on Times list of the ten best memes of 2019.
In August 2021, Kondo followed up Tidying Up with Marie Kondo with a similar series for Netflix titled Sparking Joy with Marie Kondo.
Personal life
Kondo married Kawahara Takumi in 2012. At the time they met, Kawahara was working in sales-support and marketing at a corporation in Osaka. Once Kondo's career was established, he left his job to become her manager and, eventually, CEO of Konmari-Media, LLC.
The couple have two daughters and a son. After getting married, they lived in Tokyo; the couple later moved to San Francisco and then Los Angeles.
After the birth of her third child, Kondo's rigorous attitude towards tidying her home relaxed in order to make room for more personal priorities at this stage of her life.
Publications
Jinsei ga Tokimeku Katazuke no Mahō (人生がときめく片づけの魔法). Tokyo: Sunmark Shuppan, 2011;
English translation. The life-changing Magic of Tidying up: The Japanese Art of Decluttering and Organizing. New York: Ten Speed Press, 2014; .
Jinsei ga Tokimeku Katazuke no Mahō 2 (人生がときめく片づけの魔法2). Tokyo: Sunmark Shuppan, 2012; .
Mainichi ga Tokimeku Katazuke no Mahō (毎日がときめく片付けの魔法), Tokyo: Sunmark Shuppan, 2014; .
Irasuto de Tokimeku Katazuke no Mahō = The Illustrated Guide to the Life-Changing Magic of Tidying Up (イラストでときめく片付けの魔法）. Tokyo: Sunmark Shuppan, 2015; .
Manga de Yomu Jinsei ga Tokimeku Katazuke no Mahō. Tokyo: Sunmark Publishing, 2017;
English translation. The Life-Changing Manga of Tidying Up: a magical story. New York: Ten Speed Press, 2017; .
Joy at Work: Organizing Your Professional Life co-written with Scott Sonenshein. New York: Little, Brown Spark, 2020;
References
External links
1984 births
21st-century Japanese writers
American television personalities
American women television personalities
Cleaning
Internet memes introduced in 2019
Japanese non-fiction writers
Japanese Shintoists
Japanese women television personalities
Japanese women writers
Living people
Ordering
Tokyo Woman's Christian University alumni
Writers from Osaka
Writers from Tokyo
Shorty Award winners
Japanese expatriates in the United States | Marie Kondo | [
"Chemistry"
] | 1,643 | [
"Cleaning",
"Surface science"
] |
44,217,123 | https://en.wikipedia.org/wiki/C9H13N5O3 | {{DISPLAYTITLE:C9H13N5O3}}
The molecular formula C9H13N5O3 (molar mass: 239.235 g/mol) may refer to:
Dihydrobiopterin (BH2)
S2242
Molecular formulas | C9H13N5O3 | [
"Physics",
"Chemistry"
] | 62 | [
"Molecules",
"Set index articles on molecular formulas",
"Isomerism",
"Molecular formulas",
"Matter"
] |
44,217,608 | https://en.wikipedia.org/wiki/Amide%20ring | Amide Rings are small motifs in proteins and polypeptides. They consist of 9-atom or 11-atom rings formed by two CO...HN hydrogen bonds between a side chain amide group and the main chain atoms of a short polypeptide. They are observed with glutamine or asparagine side chains within proteins and polypeptides. Structurally similar rings occur in the binding of purine, pyrimidine and nicotinamide bases to the main chain atoms of proteins. About 4% of asparagines and glutamines form amide rings; in databases of protein domain structures, one is present, on average, every other protein.
In such rings the polypeptide has the conformation of beta sheet or of type II polyproline helix (PPII). A number of glutamines and asparagines help bind short peptides (with the PPII conformation) in the groove of class II MHC (Major Histocompatibility Complex) proteins by forming these motifs. An 11-atom amide ring, involving a glutamine residue, occurs at the interior of the light chain variable domains of some Immunoglobulin G antibodies and assists in linking the two beta-sheets.
An amide ring is employed in the specificity of the adaptor protein GRB2 for a particular asparagine within proteins it binds. GRB2 binds strongly to the pentapeptide EYINQ (when the tyrosine is phosphorylated); in such structures a 9-atom amide ring occurs between the amide side chain of the pentapeptide's asparagine and the main chain atoms of residue 109 of GRB2.
References
External links
Motivated Proteins: ;
PDBeMotif: .
Protein structural motifs | Amide ring | [
"Chemistry",
"Biology"
] | 385 | [
"Biochemistry stubs",
"Protein structural motifs",
"Protein stubs",
"Protein classification"
] |
44,217,724 | https://en.wikipedia.org/wiki/Victivallis%20vadensis | Victivallis vadensis is a Gram-negative, coccus-shaped, bacteria found in the human digestive tract. It measures approximately 0.5-1.3 micrometers in diameter, is non-motile and chemoorganotrophic, and does not form spores. Victivallis vadensis is strictly anaerobic, as are 90 percent of the bacteria in the human gastrointestinal system.
History
Victivallis vadensis was originally known as strain CelloT, as it is able to use cellobiose as a carbon source. It was later renamed for an area in the Netherlands, known as “Food Valley”, near the scientists at Wageningen University, who first identified the organism. (Victus is Latin for food; vallis is Latin for valley.)
Diversity
Victavallis vadensis is a facultative anaerobe, like most gut microbes. It has only been sourced from human feces to date and is therefore known only to exist in the human gastrointestinal tract, and is currently the only organism belonging to the order Victivallales and genus Victivallis. Through 16S rRNA sequencing, it has been determined that strain CelloT forms its own cluster in the division Verrumicrobia, and two related but uncultured clones have been found that have a 94% 16S rRNA gene sequence similarity.
The Victavallis vadensis genome contains 4,577,257 bases with 3,541 protein coding sequences, of which 2,031 are functional. G-C bases make up 59.5 percent of the DNA. This bacteria is most closely related to Lentisphaera araneosa with 84.4 percent of the same 16S rRNA. These two organisms are also differentiated based on the environments in which each is found. Lentisphaera spp. are found in sea water, while V. vadensis is found in the human digestive system.
View the latest Victavallis vadensis genetic sequencing data here:
GenBank record ABDE02000001.1
GenBank record ABDE02000027.1
Bacteria -> Lentisphaerota -> which includes Oligosphaera ethanolica, Lentisphaera araneosa, and Victivallis vadensis
Biochemistry
Because more than half of the human gut microbiome has yet to be cultured, newly discovered species like Victivallis vadensis require extensive culture testing to determine in what situations they best thrive. This microbe, taken from a human fecal sample, was first cultured in the Netherlands at an optimal temperature of 37 degrees Celsius and 6.5 pH. Researchers there discovered that it grows best in liquid or soft agar with one of the following sugars: cellobiose, fructose, galactose, glucose, lactose, lactulose, maltose, maltotriose, mannitol, melibiose, myo-inositol, raftilose, rhamnose, ribose, sucrose and zylose, which it uses fermentatively. Formation of bacterial colonies under these conditions takes roughly 10 days.
Victivallis vadensis forms a slime layer outside of its cell membrane, which appears halo-like when examined microscopically. Researchers could also see assemblies with dense groups of electrons within the cells, which they believe to be protein precipitates or used for cell storage. Colonies are lens shaped, beige and shiny. It is able to be cultured syntrophically with Methanospirillum hungatei, where it produces methane from glucose in appropriate media. When attempting to isolate in culture, streptomycin and polymyxin B can be added to the media in order to prevent growth of contaminating agents; therefore, Victivallis vadensis is streptomycin and polymyxin B-resistant.
References
External links
Type strain of Victivallis vadensis at BacDive - the Bacterial Diversity Metadatabase
Gram-negative bacteria
Gut flora bacteria
Lentisphaerota | Victivallis vadensis | [
"Biology"
] | 866 | [
"Gut flora bacteria",
"Bacteria"
] |
44,217,963 | https://en.wikipedia.org/wiki/Clebsch%E2%80%93Gordan%20coefficients%20for%20SU%283%29 | In mathematical physics, Clebsch–Gordan coefficients are the expansion coefficients of total angular momentum eigenstates in an uncoupled tensor product basis. Mathematically, they specify the decomposition of the tensor product of two irreducible representations into a direct sum of irreducible representations, where the type and the multiplicities of these irreducible representations are known abstractly. The name derives from the German mathematicians Alfred Clebsch (1833–1872) and Paul Gordan (1837–1912), who encountered an equivalent problem in invariant theory.
Generalization to SU(3) of Clebsch–Gordan coefficients is useful because of their utility in characterizing hadronic decays, where a flavor-SU(3) symmetry exists (the eightfold way) that connects the three light quarks: up, down, and strange.
SU(3) group
The special unitary group SU is the group of unitary matrices whose determinant is equal to 1. This set is closed under matrix multiplication. All transformations characterized by the special unitary group leave norms unchanged. The symmetry appears in the light quark flavour symmetry (among up, down, and strange quarks) dubbed the Eightfold Way (physics). The same group acts in quantum chromodynamics on the colour quantum numbers of the quarks that form the fundamental (triplet) representation of the group.
The group is a subgroup of group , the group of all 3×3 unitary matrices. The unitarity condition imposes nine constraint relations on the total 18 degrees of freedom of a 3×3 complex matrix. Thus, the dimension of the group is 9. Furthermore, multiplying a U by a phase, leaves the norm invariant. Thus can be decomposed into a direct product . Because of this additional constraint, has dimension 8.
Generators of the Lie algebra
Every unitary matrix can be written in the form
where H is hermitian. The elements of can be expressed as
where are the 8 linearly independent matrices forming the basis of the Lie algebra of , in the triplet representation. The unit determinant condition requires the matrices to be traceless, since
.
An explicit basis in the fundamental, 3, representation can be constructed in analogy to the Pauli matrix algebra of the spin operators. It consists of the Gell-Mann matrices,
These are the generators of the group in the triplet representation, and they are normalized as
The Lie algebra structure constants of the group are given by the commutators of
where are the structure constants completely antisymmetric and are analogous to the Levi-Civita symbol of .
In general, they vanish, unless they contain an odd number of indices from the set {2,5,7}, corresponding to the antisymmetric s. Note .
Moreover,
where are the completely symmetric coefficient constants. They vanish if the number of indices from the set is odd. In terms of the matrices,
Standard basis
A slightly differently normalized standard basis consists of the F-spin operators, which are defined as for the 3, and are utilized to apply to any representation of this algebra.
The Cartan–Weyl basis of the Lie algebra of is obtained by another change of basis, where one defines,
Because of the factors of i in these formulas, this is technically a basis for the complexification of the su(3) Lie algebra, namely sl(3,C). The preceding basis is then essentially the same one used in Hall's book.
Commutation algebra of the generators
The standard form of generators of the group satisfies the commutation relations given below,
All other commutation relations follow from hermitian conjugation of these operators.
These commutation relations can be used to construct the irreducible representations of the group.
The representations of the group lie in the 2-dimensional plane. Here, stands for the z-component of Isospin and is the Hypercharge, and they comprise the (abelian) Cartan subalgebra of the full Lie algebra. The maximum number of mutually commuting generators of a Lie algebra is called its rank: has rank 2. The remaining 6 generators, the ± ladder operators, correspond to the 6 roots arranged on the 2-dimensional hexagonal lattice of the figure.
Casimir operators
The Casimir operator is an operator that commutes with all the generators of the Lie group. In the case of , the quadratic operator is the only independent such operator.
In the case of group, by contrast, two independent Casimir operators can be constructed, a quadratic and a cubic: they are,
These Casimir operators serve to label the irreducible representations of the Lie group algebra , because all states in a given representation assume the same value for each Casimir operator, which serves as the identity in a space with the dimension of that representation. This is because states in a given representation are connected by the action of the generators of the Lie algebra, and all generators commute with the Casimir operators.
For example, for the triplet representation, , the eigenvalue of is 4/3, and of , 10/9.
More generally, from Freudenthal's formula, for generic , the eigenvalue of is
.
The eigenvalue ("anomaly coefficient") of is
It is an odd function under the interchange . Consequently, it vanishes for real representations , such as the adjoint, , i.e. both and anomalies vanish for it.
Representations of the SU(3) group
The irreducible representations of SU(3) are analyzed in various places, including Hall's book. Since the SU(3) group is simply connected, the representations are in one-to-one correspondence with the representations of its Lie algebra su(3), or the complexification of its Lie algebra, sl(3,C).
We label the representations as D(p,q), with p and q being non-negative integers, where in physical terms, p is the number of quarks and q is the number of antiquarks. Mathematically, the representation D(p,q) may be constructed by tensoring together p copies of the standard 3-dimensional representation and q copies of the dual of the standard representation, and then extracting an irreducible invariant subspace. (See also the section of Young tableaux below: is the number of single-box columns, "quarks", and the number of double-box columns, "antiquarks").
Still another way to think about the parameters p and q is as the maximum eigenvalues of the diagonal matrices
.
(The elements and are linear combinations of the elements and , but normalized so that the eigenvalues of and are integers.)
This is to be compared to the representation theory of SU(2), where the irreducible representations are labeled by the maximum eigenvalue of a single element, h.
The representations have dimension
their irreducible characters are given by
and the corresponding Haar measure is
such that and ,
An multiplet may be completely specified by five labels, two of which, the eigenvalues of the two Casimirs, are common to all members of the multiplet. This generalizes the mere two labels for multiplets, namely the eigenvalues of its quadratic Casimir and of 3.
Since , we can
label different states by the eigenvalues of and operators, , for a given eigenvalue of the isospin Casimir. The action of operators on this states are,
Here,
and
All the other states of the representation can be constructed by the successive application of the ladder operators and and by identifying the base states which are annihilated by the action of the lowering operators. These operators can be pictured as arrows whose endpoints form the vertices of a hexagon (picture for generators above).
Clebsch–Gordan coefficient for SU(3)
The product representation of two irreducible representations and is generally reducible. Symbolically,
where is an integer.
For example, two octets (adjoints) compose to
that is, their product reduces to an icosaseptet (27), decuplet, two octets, an antidecuplet, and a singlet, 64 states in all.
The right-hand series is called the Clebsch–Gordan series. It implies that the representation appears times in the reduction of this direct product of with .
Now a complete set of operators is needed to specify uniquely the states of each irreducible representation inside the one just reduced.
The complete set of commuting operators in the case of the irreducible representation is
where
.
The states of the above direct product representation are thus completely represented by the set of operators
where the number in the parentheses designates the representation on which the operator acts.
An alternate set of commuting operators can be found for the direct product representation, if one considers the following set of operators,
Thus, the set of commuting operators includes
This is a set of nine operators only. But the set must contain ten operators to define all the states of the direct product representation uniquely. To find the last operator , one must look outside the group. It is necessary to distinguish different for similar values of and .
Thus, any state in the direct product representation can be represented by the ket,
also using the second complete set of commuting operator, we can define the states in the direct product representation as
We can drop the from the state and label the states as
using the operators from the first set, and,
using the operators from the second set.
Both these states span the direct product representation and any states in the representation can be labeled by suitable choice of the eigenvalues.
Using the completeness relation,
Here, the coefficients
are the Clebsch–Gordan coefficients.
A different notation
To avoid confusion, the eigenvalues can be simultaneously denoted by and the eigenvalues are simultaneously denoted by . Then the eigenstate of the direct product representation can be denoted by
where is the eigenvalues of and is the eigenvalues of denoted simultaneously. Here, the quantity expressed by the parenthesis is the Wigner 3-j symbol.
Furthermore, are considered to be the basis states of and are the basis states of . Also are the basis states of the product representation. Here represents the combined eigenvalues and respectively.
Thus the unitary transformations that connects the two bases are
This is a comparatively compact notation. Here,
are the Clebsch–Gordan coefficients.
Orthogonality relations
The Clebsch–Gordan coefficients form a real orthogonal matrix. Therefore,
Also, they follow the following orthogonality relations,
Symmetry properties
If an irreducible representation appears in the Clebsch–Gordan series of , then it must appear in the Clebsch–Gordan series of . Which implies,
Where
Since the Clebsch–Gordan coefficients are all real, the following symmetry property can be deduced,
Where .
Symmetry group of the 3D oscillator Hamiltonian operator
A three-dimensional harmonic oscillator is described by the Hamiltonian
where the spring constant, the mass and the Planck constant have been absorbed into the definition of the variables, .
It is seen that this Hamiltonian is symmetric under coordinate transformations that preserve the value of . Thus, any operators in the group keep this Hamiltonian invariant.
More significantly, since the Hamiltonian is Hermitian, it further remains invariant under operation by elements of the much larger group.
More systematically, operators such as the Ladder operators
and
can be constructed which raise and lower the eigenvalue of the Hamiltonian operator by 1.
The operators and are not hermitian; but hermitian operators can be constructed from different combinations of them, namely,
.
There are nine such operators for i, j = 1, 2, 3.
The nine hermitian operators formed by the bilinear forms are controlled by the fundamental commutators
and seen to not commute among themselves. As a result, this complete set of operators don't share their eigenvectors in common, and they cannot be diagonalized simultaneously. The group is thus non-Abelian and degeneracies may be present in the Hamiltonian, as indicated.
The Hamiltonian of the 3D isotropic harmonic oscillator, when written in terms of the operator amounts to
.
The Hamiltonian has 8-fold degeneracy. A successive application of and † on the left preserves the Hamiltonian invariant, since it increases by 1 and decrease by 1, thereby keeping the total
constant. (cf. quantum harmonic oscillator)
Maximally commuting set of operators
Since the operators belonging to the symmetry group of Hamiltonian do not always form an Abelian group, a common eigenbasis cannot be found that diagonalizes all of them simultaneously. Instead, we take the maximally commuting set of operators from the symmetry group of the Hamiltonian, and try to reduce the matrix representations of the group into irreducible representations.
Hilbert space of two systems
The Hilbert space of two particles is the tensor product of the two Hilbert spaces of the two individual particles,
where and are the Hilbert space of the first and second particles, respectively.
The operators in each of the Hilbert spaces have their own commutation relations, and an operator of one Hilbert space commutes with an operator from the other Hilbert space. Thus the symmetry group of the two particle Hamiltonian operator is the superset of the symmetry groups of the Hamiltonian operators of individual particles. If the individual Hilbert spaces are -dimensional, the combined Hilbert space is -dimensional.
Clebsch–Gordan coefficient in this case
The symmetry group of the Hamiltonian is . As a result, the Clebsch–Gordan coefficients can be found by expanding the uncoupled basis vectors of the symmetry group of the Hamiltonian into its coupled basis. The Clebsch–Gordan series is obtained by block-diagonalizing the Hamiltonian through the unitary transformation constructed from the eigenstates which diagonalizes the maximal set of commuting operators.
Young tableaux
A Young tableau (plural tableaux) is a method for decomposing products of an SU(N) group representation into a sum of irreducible representations. It provides the dimension and symmetry types of the irreducible representations, which is known as the Clebsch–Gordan series. Each irreducible representation corresponds to a single-particle state and a product of more than one irreducible representation indicates a multiparticle state.
Since the particles are mostly indistinguishable in quantum mechanics, this approximately relates to several permutable particles. The permutations of identical particles constitute the symmetric group S. Every -particle state of S that is made up of single-particle states of the fundamental -dimensional SU(N) multiplet belongs to an irreducible SU(N) representation. Thus, it can be used to determine the Clebsch–Gordan series for any unitary group.
Constructing the states
Any two particle wavefunction , where the indices 1,2 represents the state of particle 1 and 2, can be used to generate states of explicit symmetry using the symmetrizing and the anti-symmetrizing operators.
where the are the operator that interchanges the particles (Exchange operator).
The following relation follows:-
thus,
Starting from a multiparticle state, we can apply and repeatedly to construct states that are:
Symmetric with respect to all particles.
Antisymmetric with respect to all particles.
Mixed symmetries, i.e. symmetric or antisymmetric with respect to some particles.
Constructing the tableaux
Instead of using ψ, in Young tableaux, we use square boxes (□) to denote particles and i to denote the state of the particles.
The complete set of particles are denoted by arrangements of □s, each with its own quantum number label (i).
The tableaux is formed by stacking boxes side by side and up-down such that the states symmetrised with respect to all particles are given in a row and the states anti-symmetrised with respect to all particles lies in a single column. Following rules are followed while constructing the tableaux:
A row must not be longer than the one before it.
The quantum labels (numbers in the □) should not decrease while going left to right in a row.
The quantum labels must strictly increase while going down in a column.
Case for N = 3
For N = 3 that is in the case of SU(3), the following situation arises. In SU(3) there are three labels, they are generally designated by (u,d,s) corresponding to up, down and strange quarks which follows the SU(3) algebra. They can also be designated generically as (1,2,3). For a two-particle system, we have the following six symmetry states:
{|
|- style="vertical-align:top"
| || || || || || || || || || ||
|}
and the following three antisymmetric states:
The 1-column, 3-row tableau is the singlet, and so all tableaux of nontrivial irreps of SU(3) cannot have more than two rows. The representation has
boxes on the top row and boxes on the second row.
Clebsch–Gordan series from the tableaux
Clebsch–Gordan series is the expansion of the tensor product of two irreducible representation into direct sum of irreducible representations.
. This can be easily found out from the Young tableaux.
{| class="toccolours collapsible collapsed" width="80%" style="text-align:left"
!Procedure to obtain the Clebsch–Gordan series from Young tableaux:
|-
|
The following steps are followed to construct the Clebsch–Gordan series from the Young tableaux:
Write down the two Young diagrams for the two irreps under consideration, such as in the following example. In the second figure insert a series of the letter a in the first row, the letter b in the second row, the letter c in the third row, etc. in order to keep track of them once they are included in the various resultant diagrams:
Take the first box containing an a and appends it to the first Young diagram in all possible ways that follow the rules for creation of a Young diagram:
Then take the next box containing an a and do the same thing with it, except that we are not allowed to put two as together in the same column.
The last diagram in the curly bracket contains two a in the same column thus the diagram must be deleted. Thereby giving:
Append the last box to the diagram in curly bracket in all possible ways resulting in:
In each rows while counting from right to left, if at any point the number of a particular alphabet encountered be more than the number of the previous alphabet, then the diagram must be deleted. Here the first and the third diagram should be deleted, resulting in:
|}
Example of Clebsch–Gordan series for SU(3)
The tensor product of a triplet with an octet reducing to a deciquintuplet (15), an anti-sextet, and a triplet
appears diagrammatically as-
a total of 24 states.
Using the same procedure, any direct product representation is easily reduced.
See also
Wigner D-matrix
Tensor operator
Wigner–Eckart theorem
Representation theory
Racah W-coefficient
Gell-Mann–Okubo mass formula
References
online
Quantum mechanics
Mathematical physics
Lie algebras
Representation theory of Lie algebras | Clebsch–Gordan coefficients for SU(3) | [
"Physics",
"Mathematics"
] | 4,075 | [
"Applied mathematics",
"Theoretical physics",
"Mathematical physics",
"Quantum mechanics"
] |
44,218,028 | https://en.wikipedia.org/wiki/Schr%C3%B6der%E2%80%93Bernstein%20theorem | In set theory, the Schröder–Bernstein theorem states that, if there exist injective functions and between the sets and , then there exists a bijective function .
In terms of the cardinality of the two sets, this classically implies that if and , then ; that is, and are equipotent.
This is a useful feature in the ordering of cardinal numbers.
The theorem is named after Felix Bernstein and Ernst Schröder.
It is also known as the Cantor–Bernstein theorem or Cantor–Schröder–Bernstein theorem, after Georg Cantor, who first published it (albeit without proof).
Proof
The following proof is attributed to Julius König.
Assume without loss of generality that A and B are disjoint. For any a in A or b in B we can form a unique two-sided sequence of elements that are alternately in A and B, by repeatedly applying and to go from A to B and and to go from B to A (where defined; the inverses and are understood as partial functions.)
For any particular a, this sequence may terminate to the left or not, at a point where or is not defined.
By the fact that and are injective functions, each a in A and b in B is in exactly one such sequence to within identity: if an element occurs in two sequences, all elements to the left and to the right must be the same in both, by the definition of the sequences. Therefore, the sequences form a partition of the (disjoint) union of A and B. Hence it suffices to produce a bijection between the elements of A and B in each of the sequences separately, as follows:
Call a sequence an A-stopper if it stops at an element of A, or a B-stopper if it stops at an element of B. Otherwise, call it doubly infinite if all the elements are distinct or cyclic if it repeats. See the picture for examples.
For an A-stopper, the function is a bijection between its elements in A and its elements in B.
For a B-stopper, the function is a bijection between its elements in B and its elements in A.
For a doubly infinite sequence or a cyclic sequence, either or will do ( is used in the picture).
Corollary for surjective pair
If we assume the axiom of choice, then a pair of surjective functions and also implies the existence of a bijection. We construct an injective function from by picking a single element from the inverse image of each point in . The surjectivity of guarantees the existence of at least one element in each such inverse image. We do the same to obtain an injective function from . The Schröder-Bernstein theorem then can be applied to the injections h and k.
Examples
Bijective function from
Note: is the half open set from 0 to 1, including the boundary 0 and excluding the boundary 1.
Let with and with the two injective functions.
In line with that procedure
Then is a bijective function from .
Bijective function from
Let with
Then for one can use the expansions and with
and now one can set which defines an injective function . (Example: )
And therefore a bijective function can be constructed with the use of and .
In this case is still easy but already gets quite complicated.
Note: Of course there's a more simple way by using the (already bijective) function definition . Then would be the empty set and for all x.
History
The traditional name "Schröder–Bernstein" is based on two proofs published independently in 1898.
Cantor is often added because he first stated the theorem in 1887, while Schröder's name is often omitted because his proof turned out to be flawed while the name of Richard Dedekind, who first proved it, is not connected with the theorem.
According to Bernstein, Cantor had suggested the name equivalence theorem (Äquivalenzsatz).
1887 Cantor publishes the theorem, however without proof.
1887 On July 11, Dedekind proves the theorem (not relying on the axiom of choice) but neither publishes his proof nor tells Cantor about it. Ernst Zermelo discovered Dedekind's proof and in 1908 he publishes his own proof based on the chain theory from Dedekind's paper Was sind und was sollen die Zahlen?
1895 Cantor states the theorem in his first paper on set theory and transfinite numbers. He obtains it as an easy consequence of the linear order of cardinal numbers. However, he could not prove the latter theorem, which is shown in 1915 to be equivalent to the axiom of choice by Friedrich Moritz Hartogs.
1896 Schröder announces a proof (as a corollary of a theorem by Jevons).
1897 Bernstein, a 19-year-old student in Cantor's Seminar, presents his proof.
1897 Almost simultaneously, but independently, Schröder finds a proof.
1897 After a visit by Bernstein, Dedekind independently proves the theorem a second time.
1898 Bernstein's proof (not relying on the axiom of choice) is published by Émile Borel in his book on functions. (Communicated by Cantor at the 1897 International Congress of Mathematicians in Zürich.) In the same year, the proof also appears in Bernstein's dissertation.
1898 Schröder publishes his proof which, however, is shown to be faulty by Alwin Reinhold Korselt in 1902 (just before Schröder's death), (confirmed by Schröder), but Korselt's paper is published only in 1911.
Both proofs of Dedekind are based on his famous 1888 memoir Was sind und was sollen die Zahlen? and derive it as a corollary of a proposition equivalent to statement C in Cantor's paper, which reads and implies . Cantor observed this property as early as 1882/83 during his studies in set theory and transfinite numbers and was therefore (implicitly) relying on the axiom of choice.
Prerequisites
The 1895 proof by Cantor relied, in effect, on the axiom of choice by inferring the result as a corollary of the well-ordering theorem. However, König's proof given above shows that the result can also be proved without using the axiom of choice.
On the other hand, König's proof uses the principle of excluded middle to draw a conclusion through case analysis. As such, the above proof is not a constructive one. In fact, in a constructive set theory such as intuitionistic set theory , which adopts the full axiom of separation but dispenses with the principle of excluded middle, assuming the Schröder–Bernstein theorem implies the latter. In turn, there is no proof of König's conclusion in this or weaker constructive theories. Therefore, intuitionists do not accept the statement of the Schröder–Bernstein theorem.
There is also a proof which uses Tarski's fixed point theorem.
See also
Myhill isomorphism theorem
Netto's theorem, according to which the bijections constructed by the Schröder–Bernstein theorem between spaces of different dimensions cannot be continuous
Schröder–Bernstein theorem for measurable spaces
Schröder–Bernstein theorems for operator algebras
Schröder–Bernstein property
Notes
References
Martin Aigner & Gunter M. Ziegler (1998) Proofs from THE BOOK, § 3 Analysis: Sets and functions, Springer books , fifth edition 2014 , sixth edition 2018
External links
Cantor-Bernstein’s Theorem in a Semiring by Marcel Crabbé.
Theorems in the foundations of mathematics
Cardinal numbers
Articles containing proofs | Schröder–Bernstein theorem | [
"Mathematics"
] | 1,594 | [
"Mathematical theorems",
"Cardinal numbers",
"Foundations of mathematics",
"Mathematical logic",
"Mathematical objects",
"Infinity",
"Numbers",
"Articles containing proofs",
"Mathematical problems",
"Theorems in the foundations of mathematics"
] |
44,218,110 | https://en.wikipedia.org/wiki/Coulomb%20scattering%20state | A Coulomb scattering state in quantum mechanics (a fundamental theory in physics), describes a state of a particle where the particle is subject to Coulomb potential and is not localized to a finite region of space.
In general, Coulomb scattering state is a state in Hilbert Space that corresponds to two or more particles with positive interaction energy (assuming it to be only due to Coulomb interaction), which means, the energy of the system is greater than total energy of each separate particles constituting the system therefore these particles are not bound. The energy spectrum of such scattering state is continuous unlike discrete spectrum of bound states in Coulomb Potential.
Energy eigenvalues
The eigenvalues of energy corresponding to these states are positive, continuous and extend from zero to infinity. Each of these eigenvalues are infinitely degenerate. The corresponding wave functions of scattering states in the Coulomb potential field are the Coulomb wave function.
The mathematical treatment of such states, being long range potential fields, differ from other short range potentials (for example Yukawa Potential).
References
Quantum states | Coulomb scattering state | [
"Physics"
] | 227 | [
"Quantum states",
"Quantum mechanics"
] |
44,218,867 | https://en.wikipedia.org/wiki/MitoMap | MitoMap is a real time haplotyping protocol that analyzes pathogenic variants that cause several mitochondrial diseases. It was carried out real-time for the first time during the 2013 NexGen Genomics & Bioinformatics Technologies conference at Delhi, India from November 14–16. The results have been published online.
References
2013 introductions
Bioinformatics | MitoMap | [
"Chemistry",
"Engineering",
"Biology"
] | 77 | [
"Biological engineering",
"Bioinformatics stubs",
"Biotechnology stubs",
"Biochemistry stubs",
"Bioinformatics"
] |
61,814,067 | https://en.wikipedia.org/wiki/David%20Robertson%20%28engineer%29 | David Robertson (1875 – 1941) was the first Professor of Electrical Engineering at Bristol University. Robertson had wide interests and one of these was horology – he wanted to provide the foundation of what we could call “horological engineering”, that is, a firm science-based approach to the design of accurate mechanical clocks. He contributed a long series on the scientific foundations of precision clocks to the Horological Journal which was the main publication for the trade in the UK; he and his students undertook research on clocks and pendulums (some funded by the Society of Merchant Venturers); and he designed at least one notable clock, to keep University time and control the chiming of Great George in the Wills Memorial Building from its inauguration on 1925, for which he also designed the chiming mechanism.
Today, we get accurate time from atomic clock ensembles in observatories round the world, compared and distributed by GPS satellites and over the internet, and displayed on almost any public or personal screen. Accurate time has become ubiquitous and its maintenance a branch of information and communications technology. A century ago none of this existed, and the world depended on the pendulum clock to keep its time, referenced to astronomical observations. There was a scientific literature on the behaviour of pendulums and clocks; and a widespread craft-based industry making timepieces; but it could not be said that horology was a branch of engineering.
Robertson became Professor of Electrical Engineering in Merchant Venturer’s Technical College in 1902. MVTC merged with University College Bristol when the latter was granted a Royal Charter in 1909 and became the engineering faculty of the new University of Bristol – Robertson then became the first professor of the subject in the faculty. He served in this post until his death in 1941. Clock-wise, the Shortt Synchronome Free Pendulum clock entered service at the Royal Observatory in 1923 and kept Greenwich, and therefore the nation’s, time until supplanted by quartz clocks in the 1940s. Throughout Robertson’s career therefore, pendulum time was paramount. Suppliers such as the Synchronome Company or Gents of Leicester could by 1925 have supplied perfectly satisfactory and well-proven systems to run the bell and slave clocks throughout the building. The fact that the University chose to commission a unique and original design is a tribute perhaps to its pride in the new building and to its distinguished Professor, who was able to put into practice the principles that he had developed.
The Robertson Clock
Originally mounted in an interior foyer of the Wills Memorial Building, Robertson's clock is housed in an oak case 1753 x 837 x 310 mm (h/w/d), originally carried on stout oak “dogs” let into the masonry of an internal wall. The case was also secured to the wall through its back, but does not support any of the mechanisms, which are separately mounted through the case back into the wall using studs. The opening front door is fully glazed. In its new home in Queen’s Building the original studs are re-mounted on to a large steel plate, firmly screwed to the reinforced concrete wall.
At the top of the case a clock dial displays hours and minutes as kept by the pendulum. The dial is a standard Gents slave clock movement which is advanced by a pulse every 30s, counted down from seconds pulses generated by the pendulum. Additional circuits in the clock once generated other half-minute pulses that controlled 3 strings of similar slave clocks throughout the building.
Right down the centre of the case is the pendulum, of the order of a metre long and with a period of 2 seconds. It is suspended from a bracket attached to a massive iron casting bolted through to the wall, which also carries the “escapement” mechanism to the right under the face. This drives the pendulum with a small impulse of force every second, generated by the drop of a small weight under the control of an electromagnet. Part of the mechanism includes a 60-tooth ratchet wheel advanced on every pendulum swing by a pawl driven by the electromagnet. Originally this operated a pair of contacts by two pins on its periphery to generate the half-minute pulses, but at some stage these contacts were removed.
To the left of the pendulum is the regulator. This is arranged to apply a small force to the pendulum which through an ingenious linkage effectively works against gravity, slowing the pendulum down. The force comes from a torque generated by a spiral hair-spring, one end being attached to the pivot of a lever that forms part of the escapement linkage, the other to a disk that can be rotated in small steps by a solenoid-operated “stepper motor”. This allows the period of the pendulum to be adjusted by changing the torque, under the control of a system that compares the pendulum phase to a time standard (originally a daily pulse sent out over the telegraph network at 10.00 GMT).
Behind the pendulum and near its top is a standard aneroid barometer, and below that a mercury thermometer. These would have been used when checking the clocks’ rate, which depends on both atmospheric temperature and pressure.
To the left of the pendulum is the Civil Time Unit (CTU). This is essentially a clock that receives a pulse every second from the pendulum and keeps track of local time, GMT or BST depending on the season, to control the pulses sent to Great George to make it chime on the hours, 0700 through 2100 except Sundays. The CTU was driven by its own electromagnet.
On the right is the Greenwich Time Unit (GTU), which essentially kept GMT by counting seconds impulses but also controlled the sequencing of the synchronising system around 10.00 am GMT every day. Again, the GTU had its own electromagnet drive.
Behind the wall to which the clock was mounted there was a Control Box that housed several terminal frames, some relays, and ancillary components, that were connected to contacts on the TUs by wires going through the wall. Most of this has now been lost. The clock and its circuits were power by a 24 volt lead-acid battery, possibly also housed in this room. This Control Box has also been recovered and will be installed beside the clock case to house support electronics.
References
Horology
British electrical engineers
1875 births
1941 deaths | David Robertson (engineer) | [
"Physics"
] | 1,299 | [
"Spacetime",
"Horology",
"Physical quantities",
"Time"
] |
61,814,755 | https://en.wikipedia.org/wiki/Elizabeth%20Donnelly%20%28engineer%29 | Elizabeth Donnelly is a British engineer and executive. She is currently the chief executive officer of Women's Engineering Society United Kingdom. Donnelly was appointed CEO on 23 August 2018.
A systems engineer by education, Donnelly worked with companies such as Rolls-Royce. She was a founding member of the Royal Aeronautical Society’s (RAeS) Women in Aviation and Aerospace Committee.
Career
Donnelly began her career in Systems Engineering studying Databases and Systems Thinking: Managing Complexity at Open University before she specialized in Systems Thinking and graduated with a Masters in Systems Thinking in Practice. In 2005, she started work with Rolls-Royce as an adviser on lobbying governments to support trade unions. In 2008 Donnelly became a Non-Executive Director of the East Midlands Developments Agency. She worked as Head of Skills to lead skills policy in ADS Group Ltd, the trade organization for aerospace, defence and security in the United Kingdom.
In 2013, Donnelly set up her own company, Pereloquens Ltd. In August 2018, Elizabeth was appointed the Chief Executive Officer of the Women's Engineering Society (WES) to replace Kirsten Bodley.
References
1968 births
Living people
Systems engineers
Women systems engineers
British chief executives
British women chief executives
British company founders
British women company founders
Presidents of the Women's Engineering Society
Rolls-Royce people
Alumni of the Open University | Elizabeth Donnelly (engineer) | [
"Engineering"
] | 262 | [
"Systems engineers",
"Systems engineering"
] |
61,814,797 | https://en.wikipedia.org/wiki/Cephalotheca%20foveolata | Cephalotheca foveolata is a species of fungus. It is rarely opportunistic and generally manifests as a minor subcutaneous infection.
History and taxonomy
Cephalotheca foveolata was first discovered in 2006 in a subcutaneous infection of the foot in South Korea. The fungus was said to be "foveolate" because of its small pitted ascospores. The fungus has also been called Cephalotheca faveolata by Giridharan, Verekar, Khanna, Mishra, Deshmukh in 2012. C. foveolata is morphologically and molecularly very similar to other pathogenic species of fungus, especially those within the genera of Phialemonium and Acremonium. The D1/D2 variable domains of 28S rDNA have often been used to identify C. foveolata. This is necessary to distinguish C. foveolata from Cephalotheca sulfurea which has 95% homology or Phialemonium obovatum, another closely related species.
Habitat and ecology
C. foveolata has been discovered rarely but in areas around the world that differ greatly from each other. Most cases have been reported in the southern United States or southeast Asia (South Korea, Singapore, and Hong Kong).
As a saprophyte, C. foveolata generally makes its home in the soil, but can also be found growing on wood or mushrooms. An exact niche for this fungus has yet to be detailed.
Growth and morphology
C. foveolata displays both teleomorph and anamorph stages in vitro as well as in its natural habitat, it is one of very few Ascomycetes that is able to do so. It also produces thick walled chlamydospores with a 3-6 μm diameter.
In vitro the C. foveolata is black, brown, white, orange even yellowish sometimes. The colonies reach a 45–50 mm diameter in vitro on OA or PDA media in 14 days at 25 °C. Its maximum growth temperature is 39 °C though 25 °C is optimal. When grown on PFA medium C. foveolata produces a reddish brown diffusing pigment.
Conidiogenesis occurs in vitro. These conidiogenous cells remain undifferentiated from hyphae and are monophialidic with ellipsoidal conidia at the end of short conidiophores. The conidia are translucent, cylindrical, 4-5x1.5-2 μm, and are said to be very similar to the conidia of Phialemonium. The cleistothecia fruiting bodies are dark and ciliated with a peridium made of elongated, thick walled cells.
The pitted ascospores for which C. foveolata gets its name are generally kidney shaped, 4-5x3-4x2.5-3 μm, and hyaline to brown. The sexual spores are found in translucent brown 8 celled asci.
Mechanism of pathology
C. foveolata has been described as an opportunistic human pathogen and it is potentially consumed as a contaminant on food. After the first reported case in South Korea there have been 6 other cases as of 2011. Cases have included subcutaneous infections, infections of eyes, nails, lymph nodes, cardiac tissue, bronchial fluid, and one case of bloodstream infection. Symptoms were minor for all cases except in the case of the bloodstream infection where the patient had fevers, upper back pain and shortness of breath. Patients with subcutaneous infections had chronic granulomatous inflammation around infection; otherwise, urinalysis, liver/renal function tests, stool examinations, blood counts and smears all return results within normal limits.
Treatment
When C. foveolata was first discovered in South Korea a surgical removal was performed. The patient was followed for a year afterwards and it seemed the surgery was successful. Since then many anti-fungal drugs have been tried against C. foveolata. The most effective drugs so far have been amphotericin B, posaconazole and voriconazole. They inhibit all growth after 48 hours at 35 °C. Caspofungin causes abnormal growth after 24 hours and is not considered effective. Itraconazole is reported with conflicting levels of effectiveness. C. foveolata seems to be resistant to AMB, itraconazole, and terbinafine.
Medicinal uses
C. foveolata produces a metabolite called sclerotiorin. Sclerotiorin has been shown to induce apoptosis in colon cancer cells by activating a pathway leading to caspase-3 activation.
References
Sordariales
Fungus species | Cephalotheca foveolata | [
"Biology"
] | 1,002 | [
"Fungi",
"Fungus species"
] |
61,817,142 | https://en.wikipedia.org/wiki/Alvin%20Van%20Valkenburg | Alvin Van Valkenburg, Jr. (12 August 1913, Schenectady, New York – 5 December 1991, Tucson, Arizona) was an experimental physicist, geologist, geochemist, and inventor, known as one of the four co-inventors of the diamond anvil cell (DAC).
Alvin Van Valkenburg, Jr. graduated in 1936 from Schenectady's Union College with a B.S. in geology and in 1938 from the University of Colorado Boulder with an M.S. in mineralogy and petrology. After returning to Schenectady to teach at Union College, he moved to the Boston area, where he worked from 1941 to 1945 at the Charleston Navy Yard as a physicist in charge of degaussing ships. During WWII he enrolled as a graduate student at Harvard University, where he studied under Percy Bridgman and the mineralogist Esper S. Larsen, Jr. (1879–1961). In 1945 Van Valkenburg became employed at the National Bureau of Standards (NBS) in Washington, DC. From 1945 to 1946 he pursued graduate studies at Johns Hopkins University. He married Elsie Victoria Erling, whom he met in Washington, on 1 June 1946 at the Ebenezer Lutheran Church in Minneapolis.
Van Valkenburg is generally considered the originator of the practice of placing a washer-shaped gasket of extremely thin (about .3 mm) metal foil between the two diamond faces of the DAC. The gasket (made of a metal such as rhenium or tungsten) flows under ultra-high pressure and fills the central hole with fluid to achieve hydrostatic conditions. The tiny sample to be analyzed is compressed between the two opposing culets (tips) of diamond. The gasket is used to maintain the sample's contact with the culets, where the pressure is at a maximum.
In 1964 he left the NBS and became employed at the National Science Foundation (NSF). There he was director of the geochemistry program from 1964 to 1970 and retired in 1974. From 1974 to 1980 he was a guest investigator at the Geophysical Laboratory. In 1980 he moved to Tucson, Arizona and transferred his small business of manufacturing and selling DACs from Washington, DC to Tucson, where he was a business partner with his son, Eric.
In 1986 the Franklin Institute awarded Van Valkenburg the John Price Wetherill Medal for his co-invention of the DAC, which "has revolutionized high pressure research, by allowing static pressures equivalent to that in the earth's core to be produced in the laboratory."
Upon his death in 1991 Alvin Van Valkenburg was survived by his widow, his son, two daughters, and two grandchildren. The Gordon Research Conference on High Pressure gives an award named after him.
Selected publications
References
1913 births
1991 deaths
Union College (New York) alumni
University of Colorado Boulder alumni
Experimental physicists
20th-century American physicists
20th-century American inventors
High pressure science
People from Schenectady, New York | Alvin Van Valkenburg | [
"Physics"
] | 621 | [
"Applied and interdisciplinary physics",
"Experimental physics",
"Experimental physicists",
"High pressure science"
] |
61,820,316 | https://en.wikipedia.org/wiki/Archa%20%28document%20store%29 | An archa or arca (plural archae) was a mediaeval document repository, such as a chest, associated with the financial records of Jews in England at the time.
According to Jewish Communities and Records, UK, the archa was "an official chest, provided with three locks and seals, in which a counterpart of all deeds and contracts involving Jews was to be deposited in order to preserve the records." Similarly, The Jewish Encyclopedia of 1906 describes an archa as a "repository in which chirographs and other deeds were preserved."
Worcester and Winchester were two of the 26 Jewish centres of the time to have archae. The introduction of archae in Worcester was part of the reorganization of English Jewry ordered by King Richard I in light of the massacres of Jews that took place in 1189-1190 at, and shortly following, his coronation. These massacres resulted in a heavy loss of Crown revenue partly thanks to the destruction result of Jewish financial records by the murderous mob (in order to conceal evidence of debts due to the Jews). The archae were intended to safeguard the royal rights in case of future disorder. All Jewish possessions and credits were to be registered and several cities were designated as centres for all Jewish business operations and registration of Jewish financial transactions. In each centre, a bureau was set up consisting of two reputable Jews and two Christian clerks, under the supervision of a representative of the newly established central authority that became known as the Exchequer of the Jews.
See also
References
Further reading
Scott, K. (1950) "The Jewish Arcae", in: The Cambridge Law Journal, 10:446–455. Cambridge: Cambridge University Press .
Information management
Accounting source documents
Archives in England
Medieval English Jews | Archa (document store) | [
"Technology"
] | 355 | [
"Information systems",
"Information management"
] |
61,822,442 | https://en.wikipedia.org/wiki/Fry%20Medal | The F. E. J. Fry Medal is an annual award for zoology given by the Canadian Society of Zoologists.
It is presented to "the Canadian zoologist who has made an outstanding contribution to knowledge and understanding of an area in zoology". The recipient is expected to give a lecture at the next annual conference.
The award was established in 1974 in honour of Frederick E.J. Fry, the Canadian ichthyologist and aquatic ecologist, in recognition of his contribution to science in Canada.
Recipients
Source
See also
List of biologists
List of biology awards
List of awards named after people
References
Canadian science and technology awards
Awards established in 1974
Biology awards | Fry Medal | [
"Technology"
] | 132 | [
"Science and technology awards",
"Biology awards"
] |
61,823,811 | https://en.wikipedia.org/wiki/Identifier%20%28computer%20languages%29 | In computer programming languages, an identifier is a lexical token (also called a symbol, but not to be confused with the symbol primitive data type) that names the language's entities. Some of the kinds of entities an identifier might denote include variables, data types, labels, subroutines, and modules.
Lexical form
Which character sequences constitute identifiers depends on the lexical grammar of the language. A common rule is alphanumeric sequences, with underscore also allowed (in some languages, _ is not allowed), and with the condition that it can not begin with a numerical digit (to simplify lexing by avoiding confusing with integer literals) – so foo, foo1, foo_bar, _foo are allowed, but 1foo is not – this is the definition used in earlier versions of C and C++, Python, and many other languages. Later versions of these languages, along with many other modern languages, support many more Unicode characters in an identifier. However, a common restriction is not to permit whitespace characters and language operators; this simplifies tokenization by making it free-form and context-free. For example, forbidding + in identifiers due to its use as a binary operation means that a+b and a + b can be tokenized the same, while if it were allowed, a+b would be an identifier, not an addition. Whitespace in identifier is particularly problematic, as if spaces are allowed in identifiers, then a clause such as if rainy day then 1 is legal, with rainy day as an identifier, but tokenizing this requires the phrasal context of being in the condition of an if clause. Some languages do allow spaces in identifiers, however, such as ALGOL 68 and some ALGOL variants – for example, the following is a valid statement: real half pi; which could be entered as .real. half pi; (keywords are represented in boldface, concretely via stropping). In ALGOL this was possible because keywords are syntactically differentiated, so there is no risk of collision or ambiguity, spaces are eliminated during the line reconstruction phase, and the source was processed via scannerless parsing, so lexing could be context-sensitive.
In most languages, some character sequences have the lexical form of an identifier but are known as keywords – for example, if is frequently a keyword for an if clause, but lexically is of the same form as ig or foo namely a sequence of letters. This overlap can be handled in various ways: these may be forbidden from being identifiers – which simplifies tokenization and parsing – in which case they are reserved words; they may both be allowed but distinguished in other ways, such as via stropping; or keyword sequences may be allowed as identifiers and which sense is determined from context, which requires a context-sensitive lexer. Non-keywords may also be reserved words (forbidden as identifiers), particularly for forward compatibility, in case a word may become a keyword in future. In a few languages, e.g., PL/1, the distinction is not clear.
Semantics
The scope, or accessibility within a program of an identifier can be either local or global. A global identifier is declared outside of functions and is available throughout the program. A local identifier is declared within a specific function and only available within that function.
For implementations of programming languages that are using a compiler, identifiers are often only compile time entities. That is, at runtime the compiled program contains references to memory addresses and offsets rather than the textual identifier tokens (these memory addresses, or offsets, having been assigned by the compiler to each identifier).
In languages that support reflection, such as interactive evaluation of source code (using an interpreter or an incremental compiler), identifiers are also runtime entities, sometimes even as first-class objects that can be freely manipulated and evaluated. In Lisp, these are called symbols.
Compilers and interpreters do not usually assign any semantic meaning to an identifier based on the actual character sequence used. However, there are exceptions. For example:
In Perl a variable is indicated using a prefix called a sigil, which specifies aspects of how the variable is interpreted in expressions.
In Ruby a variable is automatically considered immutable if its identifier starts with a capital letter.
In Go, the capitalization of the first letter of a variable's name determines its visibility (uppercase for public, lowercase for private).
In some languages such as Go, identifiers uniqueness is based on their spelling and their visibility.
In HTML an identifier is one of the possible attributes of an HTML element. It is unique within the document.
See also
Naming convention (programming)
References
Programming language concepts
Metadata
Syntactic entities | Identifier (computer languages) | [
"Technology"
] | 1,034 | [
"Metadata",
"Data"
] |
61,824,412 | https://en.wikipedia.org/wiki/Peripherally%20acting%20%CE%BC-opioid%20receptor%20antagonist | Peripherally acting μ-opioid receptor antagonists (PAMORAs) are a class of chemical compounds that are used to reverse adverse effects caused by opioids interacting with receptors outside the central nervous system (CNS), mainly those located in the gastrointestinal tract. PAMORAs are designed to specifically inhibit certain opioid receptors in the gastrointestinal tract and with limited ability to cross the blood–brain barrier. Therefore, PAMORAs do not affect the analgesic effects of opioids within the central nervous system.
Discovery and development
Opioid drugs are known to cause opioid-induced constipation (OIC) by inhibiting gastric emptying and decreasing peristaltic waves leading to delayed absorption of medications and more water absorption from the feces. That can result in hard and dry stool and constipation for some patients.
OIC is one of the most common adverse effects caused by opioids, so the discovery of PAMORAs can prevent the effects that often compromise pain management.
Methylnaltrexone bromide was the first medication in the drug class approved by the FDA. It was discovered in 1979 by Leon Goldberg, a pharmacologist at the University of Chicago. Having witnessed the suffering of a dying friend with OIC, Goldberg tested various derivatives of naltrexone, a drug known to block the effects of opioids. His objective was to find a drug that could not pass the blood brain barrier, without affecting the analgesic effects of the opioids. After Goldberg died, his colleagues at the university continued to develop the compound. It was approved by the FDA in April 2008, originally for OIC in adult patients with advanced illness and later in adult patients with chronic noncancer pain.
In the late 1970s, Dennis M. Zimmerman and his co-workers from Lilly Research Laboratories, Indiana, did research on structural concepts for narcotic antagonists defined in a 4-phenylpiperidine series. They reported N-methyl-trans-3,4-dimethyl-4-phenylpiperidine to be pure opioid receptor antagonist with a new pharmacophore. To increase the potency they attached a phenolic group to the aromatic ring, N-methyl-trans-3,4-dimethyl-4-(3-hydroxyphenyl)piperidine. That structure was used to design and develop other opioid receptors antagonists such as alvimopan. Alvimopan was approved later in 2008 for in-hospital use to increase the gastrointestinal function following a partial large or small bowel resection with primary anastomosis. Naloxegol was approved in September 2014 and naldemedine in March 2017, both for the treatment of OIC in adult patients with chronic cancer.
Mechanism of action
PAMORAs act by inhibiting the binding of opioids agonist to the μ-opioid receptor (MOR). The objective of PAMORAs treatment is to restore the enteric nervous system function (ENS). The MOR is found in several places in the body and PAMORAs is a competitive antagonist for binding to the receptor. The MORs in the gastrointestinal tract are the main receptors that PAMORAs are intended to block and prevent the binding of opioid agonists. PAMORAs are used in the treatment of opioid-induced bowel dysfunction (OIBD), a potential adverse effect caused by chronic opioid use. PAMORAs act on the three pathophysiological mechanisms of this adverse effect. They act on gut motility, gut secretion and sphincter function.
PAMORAs effect on gut motility is that it can increase the resting tone in the circular muscle layer. The antagonist enhances the effect on tonic inhibition of the muscle tone. This will normalize the tone in the circular muscle layer and therefore prevent opioid-induced rhythmic contractions. When these two factors are combined, it results in decreased transit time. Impliedly these effects will decrease the passive absorption of fluids which helps with decreasing OIBD symptoms such as constipation, gut spasm and abdominal cramp.
PAMORAs effect on gut secretion will help reverse the decreased cAMP formation that opioid agonists induce. Also, the antagonist will establish a normal secretion of chloride. Opioids agonists can also reduce the secretion of peptides by increasing the sympathetic nervous system through the μ-receptors in the ENS, which can lead to drier and harder stool. PAMORAs work against it so the stool becomes softer and less dry.
PAMORAs effect on the function of the sphincter is in theory to regulate the movement coordination. The antagonist can prevent sphincter of Oddi dysfunction that is caused by opioids. Antagonists can also reduce opioid-induced anal sphincter dysfunction. The dysfunction is tied to straining, hemorrhoids and incomplete emptying.
Structure–activity relationship
Even though μ-opioid receptor (MOR) targeting drugs have been used for a long time, not much is known about the structure-activity relationship and the ligand-receptor interactions on the basis of well-defined biological effects on receptor activation or inhibition. Also, the distinction in the receptor-ligand interaction patterns of agonists and antagonists is not known for sure. One theory states that the morphinans biological activity could be determined by the size of the N-substituents. For example, antagonists usually have larger substituents, such as allyl- or cyclopropyl methyl at the morphinan nitrogen, while agonists generally contain a methyl group. On the other hand, agonist activity is also shown in ligands with larger groups at the morphinan nitrogen, and therefore this hypothesis is challenged.
Structure
Methylnaltrexone bromide, naloxegol, and naldemedine all have similar structures, which is not far away from the chemical structure of morphine and other MOR-agonists. All contain a rigid pentacyclic structure that involves benzene ring (A), tetrahydrofuran ring (B), two cyclohexane rings (C and D) and a piperidine ring (E). The most important functional groups for the biological action of opioids are the hydroxyl group on the phenol, N-methyl group, ether bridge between C4 and C5, the double bond between carbon number C7 and C8 and the hydroxyl groups at C3 and C6. The phenolic ring and its 3-hydroxyl group is vital for the analgesic effects as the removal of the OH group decrease the analgesic activity 10-fold. There is another principle for the hydroxyl group on C6 as the removal enhances its activity. The increased activity is mainly because of the increased lipophilicity and the increased ability to cross the blood–brain barrier. Naldemedine has the hydroxyl group while methylnaltrexone bromide has a ketone group and naloxegol has an ester. The double bond between C7 and C8 is not required for the analgesic effect and reduction of the double bond will increase the activity. None of the antagonists has a double bond in their structure. The N-substituent on the skeleton is thought to determine the pharmacological behavior and its interaction with MOR. It is also thought to play a key role in distinguishing antagonists from agonists. Allyl group, a methylcyclopropyl group or a methylcyclobutyl as N-substituent groups are thought to lead antagonist activity.
Binding site
Agonists and antagonists form certain chemical bonds with amino acids that construct the MOR. The majority of antagonists, as well as agonists, are predicted to form charged interaction with Asp147 and a hydrogen bond with Tyr148. However, majority of antagonists also form additional polar interactions with other amino acid residues such as Lys233, Gln124, Gln229, Asn150, Trp318 and Tyr128. Only a small minority of agonists form the same additional polar interactions. Both agonists and antagonists are known to form hydrogen bonds with His297.
It can be concluded that interactions with the amino acid residues, Asp147 and Tyr148 are essential for the ligand to bind to the receptor and the molecules that form additional polar interactions with other residues are more often antagonists than agonists.
The N-substituent group can form hydrophobic bonds with Tyr326 and Trp293 and the aromatic and cyclohexane rings can form similar bonds to Met151. The backside of the ligand can also form a hydrophobic bond, but with Val300 and Ile296.
Methylnaltrexone bromide
Methylnaltrexone bromide is the bromide salt form of methylnaltrexone, a quaternary methyl derivative of noroxymorphone. The methyl group and the quaternary salt formation increase the polarity and reduce the lipid solubility thereby restricts the blood–brain-barrier penetration. Methylnaltrexone has eight times higher affinity for MOR than for κ-opioid receptor (KOR) and δ-opioid receptor (DOR). Naltrexone forms interaction with Asp147 and Tyr148 along with a hydrogen bond with Lys233.
Alvimopan
Peripherally selective trans-3,4-dimethyl-4-(3-hydroxylphenyl)piperidine opioid antagonists were developed for the treatment of gastrointestinal motility disorder by Zimmerman and his coworkers. From that, they derived the 4-(3-hydroxyphenyl)-3,4-dimethylpiperidine scaffold with functional groups spanning various sizes, charge, and polarity to reach peripheral opioid receptor antagonism while decreasing CNS drug exposure. The in vitro μ-Ki, in vivo AD50, and ED50 and peripheral index (ratio) was examined for several selective analogs, and from that, they found out that the trans-3,4-dimethyl-4-(3-hydroxyphenyl) piperidine, Alvimopan, gave the best results. The large zwitterionic structure and the high polarity prevents Alvimopan from crossing the blood–brain barrier, potency at binding peripheral MORs is thereby 200 times that of central MORs.
Naloxegol
Naloxegol is a polyethylene glycol-modified derivative of α-naloxol. Naloxegol has a similar form as naloxone as a heteropentacyclic compound both of which have an allyl group attached to the amine of the piperidine ring. However, naloxegol has a monomethoxy-terminated n=7 oligomer of PEG connected to the 6-alpha-hydroxyl group of ɑ-naloxol via an ether linkage. The PEG moiety increases the molecular weight and therefore restricts the uptake of naloxegol into the CNS. Furthermore, pegylated naloxegol becomes a substrate for the P-glycoprotein efflux transporter that transports the compound out of the CNS.
Naldemedine
Naldemedine has a similar chemical structure as naltrexone but with an additional side chain that increases the molecular weight and polar surface area of the substance. Like naloxegol, naldemedine is a substrate of the P-glycoprotein efflux transporter. These properties result in less penetration into the CNS and decrease possible inference with the effects of opioid agonists.
Naldemedine is a dual antagonist for MOR and DOR. Activation of the DOR has been known to cause nausea and/or vomiting, so a dual antagonist can decrease both OIC and nausea/vomiting.
Pharmacokinetics
The molecular weight, bioavailability, protein binding, elimination half-life, the time to achieve maximum plasma concentration and binding affinity are present in the table below.
t1/2: Biological half-life
tmax: Time to achieve maximum plasma concentration
pKi: the measurement of ligand binding affinity
Methylnaltrexone bromide has poor oral bioavailability, and for that reason, every other day it is administered subcutaneously. About half of the dose is excreted in the urine and somewhat less in feces with 85% eliminated unchanged.
Alvimopan has considerable low bioavailability (6%) due to its high binding affinity and low dissociation rate. Essentially, alvimopan is mediated by biliary secretion with an average plasma clearance of 400 ml/min. Metabolism of alvimopan is via intestinal flora resulting in hydrolysis of alvimopan to the active amide metabolite (ADL 08-0011). However, the metabolite is considered clinically irrelevant due to its low binding affinity.
When naloxegol is given with a fatty meal, absorption increases. Clearance is mostly via hepatic metabolism (P450-CYP3A) with unknown actions of the metabolites. Naloxegol has small fragments eliminated by renal excretion.
Naldemedine metabolites mainly via CYP3A to nor-naldemedine, it also metabolites via UDP-glucuronosyltransferase 1A3 to naldemedine 3-G, but in a lesser extent. Those metabolites are both opioid receptor antagonists but are less potent than the parent compound.
PAMORAs in development
Axelopran is an oral PAMORA which is under development by Theravane Biopharma. It has completed phase II in clinical trials in more than 400 patients with OIC. Axelopran has a different chemical structure from other PAMORAs but with a similar mechanism of action. It acts as an antagonist for MOR, KOR and DOR, but with higher affinity for MOR and KOR than for DOR. Like other PAMORAs, the main goal is the treatment of OIC.
Axelopran is also being investigated in fixed-dose combination (FDC) with oxycodone. It is done by using spray coating technology to create an FDC of axelopran and controlled-release oxycodone.
There is a demand for optimization of the receptor selectivity and affinity accompanied by an exploration of candidate compounds regarding their route of administration. These are the main objectives and future strategies for drug discovery and the development of PAMORAs.
Predominantly, the MORs exhibit functionally selective agonism. Therefore, future possible candidate compounds that target OIC are PAMORAs with optimized selectivity and affinity.
References
Mu-opioid receptor antagonists
Pharmacology | Peripherally acting μ-opioid receptor antagonist | [
"Chemistry"
] | 3,183 | [
"Pharmacology",
"Medicinal chemistry"
] |
61,825,772 | https://en.wikipedia.org/wiki/Mycotypha%20microspora | Mycotypha microspora, also known as Microtypha microspora, is a filamentous fungus in the division Zygomycota. It was discovered in a Citrus aurantium peel in 1932 by E. Aline Fenner, who proposed a new genus Mycotypha to accommodate it. Mycotypha africana, which is another species in the genus Mycotypha, is closely related to M. microspora. The fungus has subsequently been isolated from both outdoor and indoor settings around the world, and is typically found in soil and dung. The species rarely causes infections in humans, but has recently been involved in the clinical manifestation of the life-threatening disease mucormycosis.
Morphology and growth conditions
Mycotypha microspora is a filamentous fungus whose genus name is derived from the cattail-like appearance of its fructifications and tiny spores. It has a dense granular protoplasm and is composed of several hyphae and vacuoles. The structure is highly branched, with mycelium of varying diameters. It consists of two kinds of unispored sporangia: an inner layer containing globose spores and an outer layer with obovoid or cylindrical spores.
During the growth period, the fruiting body is coenocytic. After the fungus gradually matures, septation occurs at approximately the same time as sporulation. Mycotypha microspora colonies grow rapidly and abundantly on nutrient-rich media, such as carrot agar and potato dextrose. However, no growth occurs on low pH media. M. microspora is mesophilic, with optimal growth of cultures occurring at a temperature of , with a threshold of under which growth is inhibited. The fructifications typically form at night and thus respond unfavourably to light.
Geographical distribution and habitat
Other species present in the genus Mycotypha include M. africana, and M. indica. These species are distributed worldwide and have been geographically collected from countries including Japan, India, Finland, Zimbabwe, and certain states in the U.S. such as Arizona, Washington D.C., Kansas, California, and Iowa. These fungi are predominantly found in soil and faeces. M. microspora was initially extracted from a Citrus aurantium peel in the Netherlands, where it was found to be pathogenic. Additionally, it has reportedly been found in decaying wood and a hospital washroom in Germany. One specific case noted its presence in stool samples from a child with leukaemia.
Mycotypha microspora is an intestinal symbiont of the silverfish species Thermobia domestica. Deposited with the feces of the silverfish, the fungus was found to be responsible for arrestment and aggregation behaviour in Thermobia domestica and in the related silverfish Ctenolepisma longicaudata, but not in Lepisma saccharina. Thermobia domestica does not seem to sense the presence of M. microspora itself, but rather the fungus‘ metabolites (such as glucose) of its enzymatic digestion of cellulose.
Pathogenicity
Only a few reported cases exist where the species has been found to cause an infection in humans. M. microspora has recently been implicated as a causative factor in the pathogenesis of gastrointestinal mucormycosis in humans, which is a rare disease caused by fungi of the order Mucorales. Mucormycosis is a potentially fatal disease characterised by tissue necrosis that results from aggressive infiltration of blood vessels and subsequent formation of blood clots. The disease develops due to the binding of spore coating (CotH) proteins from the fungus to glucose regulator protein 78 (GRP78) host receptors in endothelial cells. Tissue necrosis blocks the entry of antifungals to infected sites, therefore preventing clearance and promoting circulation of the disease. Mucormycosis is highly susceptible in immunocompromised patients, and can mainly infect the body at pulmonary, rhinocerebral, cutaneous, and gastrointestinal sites. Factors that put an individual at risk for manifestation of the disease include corticosteroid use, diabetes, and ongoing neutropenia.
Treatment
Given that the disease is rare, there is a lack of experimental findings assessing the efficacy of specific treatment regimens for mucormycosis. The most reliable antifungal agent against mucormycosis is amphotericin, however the use of this in combination with voriconazole led to acute kidney injury upon admission of a 41-year-old man who was dually infected by Aspergillus fumigatus and M. microspora. In order to prevent permanent kidney damage, therapy was switched to administering the broad spectrum antifungal isavuconazole for 15 days, however this also led to complications in the patient. Ultimately, his gastrointestinal Mycotypha infection was treated with a combination of posaconazole and micafungin, which proved to be more effective than monotherapy, and he was eventually cured of the disease by surgically removing a part of his stomach in order to manage the gastrointestinal bleeding. This rare case provides some insight into potential treatment protocols for M. microspora and A. fumigatus infections in humans, however, further research that focuses on infections caused solely by M. microspora is essential in formulating a specific treatment regimen against this species.
CotH proteins are found in fungi of the order Mucorales, and blocking their function weakens their ability to invade endothelial cells, and reduces mucormycosis presentation in mice.
References
Zygomycota
Fungus species | Mycotypha microspora | [
"Biology"
] | 1,219 | [
"Fungi",
"Fungus species"
] |
61,826,117 | https://en.wikipedia.org/wiki/Thomas%20C.%20Katsouleas | Thomas Christos Katsouleas (known as "TomKat" by students) is an American physicist, engineer, and academic administrator. In February 2019, he was named the 16th president of the University of Connecticut and officially began his term in August. He resigned the presidency in 2021 and returned to the faculty.
Education
Katsouleas began his undergraduate education at Santa Monica Community College and received his bachelor's degree from University of California, Los Angeles in 1979, earning his Ph.D. in physics from UCLA in 1984.
Career
After graduating from UCLA, Katsouleas taught there for seven years before joining the faculty of the University of Southern California in 1991 as an associate professor of physics. In 1997, he was named a full professor. Katsouleas was vice provost for information services at USC and also was an associate dean of the USC Viterbi School of Engineering. Katsouleas subsequently served as the dean of the Duke University Pratt School of Engineering and, beginning in 2015, as provost and executive vice president of the University of Virginia.
On August 1, 2019, Katsouleas became the president of the University of Connecticut; the Greek Orthodox Archbishop Elpidophoros attended the inauguration ceremony. At his inauguration, Katsouleas announced the Connecticut Commitment initiative to cover the cost of tuition for qualified undergraduate and transfer students with household incomes below $50,000. Amid the financial crisis caused by the COVID-19 pandemic, the initiative was paused indefinitely in October 2020. Katsouleas also vowed to double research spending at UConn to $500 million by 2030.
Katsouleas announced key initiatives without consulting the UConn Board of Trustees. A rocky relationship with the trustees ensued. Katsouleas was also frustrated at UConn's high fringe rates and unfunded pension liabilities, which he stated made the university less competitive at winning research grants. Katsouleas resigned as UConn president effective June 30, 2021. He became a tenured professor in UConn's Department of Electrical and Computer Engineering, earning over $330,000 per year. Trustees appointed UConn Health CEO Andrew Agwunobi as interim president.
Katsouleas is an inventor and was awarded the Plasma Science Achievement Award by the Institute of Electrical Engineers in 2001. He is the author or co-author of more than 200 publications. He was elected in 1996 a fellow of the American Physical Society for "original contributions to advanced particle acceleration concepts including the invention of the Surfatron accelerator, and his detailed studies of beam loading and emittance growth in plasma accelerators."
He founded the NAE Grand Challenges Summit in Durham in 2009. In 2010, Katsouleas started Duke's Katsouleas NAE Grand Challenge Scholars Program, which challenges students to use their knowledge to work on challenges posed by the National Academy of Engineering.
References
External links
Official biography UConn
1959 births
Living people
Presidents of the University of Connecticut
Date of birth missing (living people)
University of California, Los Angeles alumni
University of California, Los Angeles faculty
20th-century American physicists
21st-century American physicists
Plasma physicists
University of Southern California faculty
Place of birth missing (living people)
Duke University faculty
University of Virginia faculty
American people of Greek descent
Fellows of the American Physical Society | Thomas C. Katsouleas | [
"Physics"
] | 678 | [
"Plasma physicists",
"Plasma physics"
] |
61,827,965 | https://en.wikipedia.org/wiki/Social%20motility | Social motility describes the motile movement of groups of cells that communicate with each other to coordinate movement based on external stimuli. There are multiple varieties of each kingdom that express social motility that provides a unique evolutionary advantages that other species do not possess. This has made them lethal killers such as African trypanosomiasis, or Myxobacteria. These evolutionary advantages have proven to increase survival rate among socially motile bacteria whether it be the ability to evade predators or communication within a swarm to form spores for long term hibernation in times of low nutrients or toxic environments.
Measuring bacterial motility
Motility assays can be utilized to quantitatively measure the macroscopic motility of a specimen. To perform a motility assay, semi-solid agar is inoculated with a small amount of a liquid suspension containing the specimen of interest. Over time, bacteria that are non-motile will remain near the initial inoculation site, while motile bacteria will spread along the media, forming a visible blur. The radius of the area of motility can be measured and compared between specimens, while the spatial patterns and spread of the visible area of motility can be altered by adding low concentrations of a known chemoattractant or chemorepellent to the medium. The motility of a species can also be measured microscopically, giving more insight into the movement of individual cells. Colonies can be examined under a microscope by using a thin layer of solidified nutrient media and a glass coverslip to create an interstitial interface at which active colony expansion can occur. This allows for the visualization of individual cells and the identification of different forms of bacterial motility present in a colony.
Communication
Bacterial cells are able to communicate with one another through the use of chemical messengers. These chemical messengers are passed from one cell to the next to control factors such as virulence, growth and nutrient conditions, etc. As first discovered in plants, diffusible signal factors (DSFs) have been found in bacteria such as Burkholderia cenocepacia and Pseudomonas aeruginosa. When individual cells are stimulated by DSF, it causes them to release their own DSF to spread the signal further and also to generate a response to the DSF often seen as growth, movement, or sporulation in unfavorable growth conditions. Via these chemical messengers, swarms of bacteria are able to increase the rate of survival compared to single cell bacteria on their own.
Benefits
Predation
Traveling in groups, often referred to as swarms, is beneficial to the organism. For instance, when Myxobacteria swarms and feeds on prey, all individual cells release hydrolytic enzymes. This abundance of metabolic enzymes allows the swarm to easily degrade and engulf the prey. Interactions between separate species of organisms in a given environment is very common. Production of toxins, usually in the form of antibodies, allows for cells to ward off other organisms from infringing on their niche. Similar to the combined release of degrading enzymes, antibodies allow for a colony of bacteria to fight off surrounding organisms in the same habitat.
Survival
Increased survival rates are seen in motile bacteria. This can be attributed to factors such as Chemotaxis, bacteria's ability to sense and migrate towards nutrients. The Chemotaxis mechanism can be amplified by social motility to alert all cells in the cluster of bacteria to move towards nutrients. The same is true of any toxic substances and the avoidance of that toxic environment by motile bacteria.
Phototaxis is a similar intracellular process to chemotaxis, and involves the directed movement of organisms in response to light. Prokaryotes are unable to sense the exact direction of light, but have still evolved mechanisms to sense and respond to the light-intensity gradient. Some halophilic archaebacteria, such as Halobacterium salinarum, use sensory rhodopsins as receptors for light and can help direct bacterial swims in areas with steep light gradients. This process is also present in eukaryotic organisms such as the green algae Chlamydomonas reinhardtii which using phototaxis to drive movement towards light to increase photosynthesis or away from areas of bright light to avoid damage to the molecular processes involved in photosynthesis.
Reproduction
Some organisms use social motility as a way to reproduce. One such organism is the slime mold Dictostelium discoideum, which forms a mobile “slug” via the aggregation of many individual amoebas. This process begins by one amoeba releasing a cyclic AMP (cAMP) signal during periods of stress, resulting in neighboring amoebas moving to this higher cAMP concentration through chemotaxis and releasing their own cAMP signals. The amoebas eventually aggregate into a single “slug,” which responds to moisture and light gradients as it searches for a good place to form a reproductive stalk and produce spores.
Examples
Swarming
Swarming motility is the coordinated movement of bacteria along a solid/semisolid surface. Swarming motility can usually be observed in a laboratory setting, depending on the conditions of media nutrient concentration, and the viscosity of the surface of the media. More information on swarming motility can be found here.
Gliding
Mechanisms that drive gliding motility are still unknown. However, despite lacking flagella, pili, and fimbriae, bacteria such as Myxococcus xanthus are able to move across surfaces in a gliding motion. Close studies of the myxococcus xanthus has proposed ideas of how the bacteria are able to move across surfaces. Inner membrane protein complexes, such as AgmU, propel the organism forward as these protein complexes function similar to the flagella complex of other motile organisms. These protein complexes, powered by a proton motive force, rotate within the membrane allowing cells to glide over surfaces.
Twitching
Built for use by many in the bacterial world, Twitching Motility is an important tool that bacteria use to move across moist surfaces. Twitching Motility uses a type IV pili that extends, tethers to a surface, and then pulls the bacteria forward. This allows for quicker growth across biofilms and fruiting bodies. Type IV pili is run by over forty genes that regulate this type of motility. Myxococcus xanthus ability to use gliding motility to move is very similar to Pseudomonas aeruginosa twitching motility.[1] Pseudomonas aeruginosa is a very motile bacteria species but it has some drawbacks, in one experiment a team of researchers discovered that if they put pressure on colonies that exhibited the quickest motility it led to decreased production of biofilm formation but drastically increased rates of motility. They then compared their quickest strain to wild type species to see if there is a need for higher rates of motility in the environment but none came close. Overall increasing speeds did not increase the chance for survival in the long run.
References
Microbiology terms | Social motility | [
"Biology"
] | 1,442 | [
"Microbiology terms"
] |
59,167,503 | https://en.wikipedia.org/wiki/NGC%202280 | NGC 2280 is a spiral galaxy located in the constellation Canis Major. It is located at a distance of about 75 million light years from Earth, which, given its apparent dimensions, means that NGC 2280 is about 135,000 light years across. It was discovered by John Herschel on February 1, 1835.
Characteristics
NGC 2280 has a small bright nucleus. The spiral arms emanate from the bulge and are narrow and of high surface magnitude in the inner part of the disk. At the outer disk the arms become broader and of lower surface magnitude and appear to have more knots. The east arm can be traced through ~540° while the west one fades after ~360°. The spiral pattern of the galaxy is undisturbed, with regular flow pattern and no evidence for a bar or oval distortion. In the nucleus of NGC 2280 lies a supermassive black hole whose mass is estimated to be between 4 and 15 million (106.88 ± 0.31 ) by measuring the galaxy's pitch angle.
Supernova
One supernova has been observed in NGC 2280. SN 2001fz, a type II supernova, was discovered by the Beijing Astronomical Observatory Supernova Survey on November 15, 2001. It had a peak magnitude of 17.4.
Nearby galaxies
NGC 2280 belongs to the NGC 2280 galaxy group, also known as LGG 138. Other members of the group are the possibly merging lenticular galaxies NGC 2292 and NGC 2293, NGC 2295, ESO 490−G010 and ESO 490−G045. Because of its large angular diameter, about one degree, the group was identified when redshift information were available, by Garcia et al. in 1993. Although there are some smaller galaxies near NGC 2280 that based on redshift could be its companions, there are no significant indications of recent interactions or tidal distortions, like warps. Gerard de Vaucouleurs had placed NGC 2280 in the same group with NGC 2139, NGC 2207, NGC 2217, and NGC 2223.
See also
List of NGC objects (2001–3000)
References
External links
Unbarred spiral galaxies
Canis Major
2280
131
19531
Astronomical objects discovered in 1835
Discoveries by John Herschel
-05-16-020
06428-2735 | NGC 2280 | [
"Astronomy"
] | 474 | [
"Canis Major",
"Constellations"
] |
59,167,681 | https://en.wikipedia.org/wiki/Doris%20M.%20Curtis%20Outstanding%20Woman%20in%20Science%20Award | The Doris M. Curtis Outstanding Woman in Science Award, also known as the Subaru Outstanding Woman in Science Award is a prize given annually by the Geological Society of America to "...women who have made a significant impact on the geosciences with their Ph.D. research." The award is named in memory of Doris Malkin Curtis, first female president of the GSA, and sponsored by Subaru.
Recipients of the award are listed below.
References
American science and technology awards
Women in science and technology | Doris M. Curtis Outstanding Woman in Science Award | [
"Technology"
] | 107 | [
"Women in science and technology"
] |
59,167,911 | https://en.wikipedia.org/wiki/Virginia%20Cornish | Virginia Wood Cornish is the Helena Rubinstein Professor of Chemistry at Columbia University.
Background and education
Cornish received her BA in chemistry in 1991, working with professor Ronald Breslow. Her PhD research, on site-specific protein labeling and mutagenesis, was carried out with Peter Schultz. Cornish was an NSF postdoctoral fellow at MIT with Robert T. Sauer. She is the first female graduate from Columbia College to be hired to a full-time faculty position since the College became coeducational in 1983.
Research
Cornish and her lab group use the tools of systems biology, synthetic biology, and DNA encoding to produce desired chemical products from specific organismic hosts. In 2016, she was part of a notable group of genomic scientists calling for increased ethical study and self-regulation as the costs and effort of creating de novo genomes plummeted. As the "read" phase of the Human Genome Project was completed in 2004, this new effort was dubbed Genome Project-Write.
Awards
2009 – Pfizer Award in Enzyme Chemistry
2009 – Irving Sigal Young Investigator Award
2003 – Sloan Foundation Fellow
References
Year of birth missing (living people)
Living people
American women chemists
Columbia College (New York) alumni
Massachusetts Institute of Technology alumni
Synthetic biologists
Human Genome Project scientists
21st-century American women | Virginia Cornish | [
"Engineering",
"Biology"
] | 262 | [
"Human Genome Project scientists",
"Synthetic biologists",
"Synthetic biology"
] |
59,168,336 | https://en.wikipedia.org/wiki/Lake%20metabolism | Lake metabolism represents a lake's balance between carbon fixation (gross primary production) and biological carbon oxidation (ecosystem respiration). Whole-lake metabolism includes the carbon fixation and oxidation from all organism within the lake, from bacteria to fishes, and is typically estimated by measuring changes in dissolved oxygen or carbon dioxide throughout the day.
Ecosystem respiration in excess of gross primary production indicates the lake receives organic material from the surrounding catchment, such as through stream or groundwater inflows or litterfall. Lake metabolism often controls the carbon dioxide emissions from or influx to lakes, but it does not account for all carbon dioxide dynamics since inputs of inorganic carbon from the surrounding catchment also influence carbon dioxide within lakes.
Concept
Estimates of lake metabolism typically rely on the measurement of dissolved oxygen or carbon dioxide, or measurements of a carbon or oxygen tracer to estimate production and consumption of organic carbon. Oxygen is produced and carbon dioxide consumed through photosynthesis and oxygen is consumed and carbon dioxide produced through respiration. Here, organic matter is symbolized by glucose, though the chemical species produced and respired through these reactions vary widely.
Photosynthesis:
Respiration:
Photosynthesis and oxygen production only occurs in the presence of light, while the consumption of oxygen via respiration occurs in both the presence and absence of light. Lake metabolism terms include:
GPP - gross primary production (e.g. total photosynthesis)
R - total respiration
- heterotrophic respiration
- autotrophic respiration
NEP - net ecosystem production = GPP - R
NPP - net primary production = GPP -
Measurement techniques
Estimating lake metabolism requires approximating processes that influence the production and consumption of organic carbon by organisms within the lake. Cyclical changes on a daily scale occur in most lakes on Earth because sunlight is available for photosynthesis and production of new carbon only for a portion of the day. Researchers can take advantage of this diel pattern to measure rates of change in carbon itself or changes in dissolved gases such as carbon dioxide or oxygen that occur on a daily scale. Although daily estimates of metabolism are most common, whole-lake metabolism can be integrated over longer time periods such as seasonal or annual rates by estimating a whole-lake carbon budget. The following sections highlight the most common ways to estimate lake metabolism across a variety of temporal and spatial scales and go over some of the assumptions of each of these methods.
Free-water methods
Measurement of diel changes in dissolved gases within the lake, also known as the "free-water" method, has quickly become the most common method of estimating lake metabolism since the wide adoption of autonomous sensors used to measure dissolved oxygen and carbon dioxide in water. The free-water method is particularly popular since many daily estimates of lake metabolism can be collected relatively cheaply and can give insights into metabolic regimes during difficult-to-observe time periods, such as during storm events. Measured changes in dissolved oxygen and carbon dioxide within a lake represents the sum of all organismal metabolism from bacteria to fishes, after accounting for abiotic changes in dissolved gases. Abiotic changes in dissolved gases include exchanges of dissolved gases between the atmosphere and lake surface, vertical or horizontal entrainment of water with differing concentrations (e.g. low-oxygen water below a lake's thermocline), or import and export of dissolved gases from inflowing streams or a lake outlet. Abiotic changes in dissolved gases can dominate changes of dissolved gases if the lake has a low metabolic rate (e.g. oligotrophic lake, cloudy day), or if there is a large event that causes abiotic factors to exceed biotic (e.g. wind event causing mixing and entrainment of low-oxygenated water). Biotic signals in dissolved gases are most evident when the sun is shining and photosynthesis is occurring, resulting in the production of dissolved oxygen and consumption of carbon dioxide. The conversion of solar energy to chemical energy is termed gross primary production (GPP) and the dissipation of this energy through biological carbon oxidation is termed ecosystem respiration (ER). High-frequency (e.g. 10 minute interval) measurements of dissolved oxygen or carbon dioxide can be translated into estimates of GPP, ER, and the difference between the two termed Net Ecosystem Production (NEP), by fitting the high-frequency data to models of lake metabolism. The governing equation for estimating lake metabolism from a single sensor located in the upper mixed layer measuring dissolved oxygen is:
DO/t = GPP-ER+F
Where F is the flux of gases between the lake and the atmosphere. Additional terms of abiotic gas flux can be added if those abiotic fluxes are deemed significant for a lake (e.g. mixing events, inflowing stream gases). Atmospheric gas exchange (F) is rarely directly measured and typically modeled by estimating lake surface turbulence from wind-driven and convective mixing. Most often, F is estimated from measurements of wind speed and atmospheric pressure, and different models for estimating F can result in significantly different estimates of lake metabolic rates depending on the study lake. Gross primary production is assumed to be zero during the night due to low or no light, and thus ER can be estimated from nighttime changes in dissolved oxygen (or carbon dioxide) after accounting for abiotic changes in dissolved oxygen. Gross primary production can be estimated assuming that ER is equal during the day and night and accounting for dissolved oxygen changes during the day, however, this assumption may not be valid in every lake.
Extracting a high signal-to-noise ratio is key to obtaining good estimates of lake metabolism from the free-water technique, and there are choices that a researcher needs to make prior to collection data and during data analyses to ensure accurate estimates. Location of dissolved gas collection (typically in the surface mixed layer), number of sensors vertically and horizontally, frequency and duration of data collection, and modeling methods need to be considered.
Free-water metabolism modeling techniques
The free-water measurement techniques require mathematical models to estimate lake metabolism metrics from high-frequency dissolved gas measurements. These models range in complexity from simple algebraic models to depth-integrated modeling using more advanced statistical techniques. Several statistical techniques have been used to estimate GPP, R, and NEP or parameters relating to these metabolism terms.
Light and dark bottle methods
The light and dark bottle method uses the same concept as the free-water method to estimate rates of metabolism - GPP only occurs during the day with solar energy while ER occurs in both the presence and absence of light. This method incubates lake water in two separate bottles, one that is clear and exposed to natural or artificial light regime and another that is sealed off from the light by wrapping the bottle in foil, paint, or another method. Changes in carbon fixation or dissolved gases are then measured over a certain time period (e.g. several hours to a day) to estimate the rate of metabolism for specific lake depths or an integrated lake water column. Carbon fixation is measured by injecting radioactive carbon isotope 14C into light and dark bottles and sampling the bottles over the time - the samples are filtered onto filter paper and the amount of 14C incorporated into algal (and bacterial) cells is estimated by measuring samples on a scintillation counter. The difference between the light and dark bottle 14C can be considered the rate of primary productivity; however, due to non-photosynthetic uptake of CO2 there is debate as to whether dark bottles should be used with the 14C method or if only a light bottle and a bottle treated with the algicide DCMU should be used. Rates of change in dissolved gases, either carbon dioxide or oxygen, need both the light and dark bottles to estimate rates of productivity and respiration.
Whole-lake carbon budget methods
Probably the most labor-intensive method of estimating a metric of lake metabolism is by measuring all the inputs and outputs of either organic or inorganic carbon to a lake over a season or year, also known as a whole-lake carbon budget. Measuring all the inputs and outputs of carbon to and from a lake can be used to estimate net ecosystem production (NEP). Since NEP is the difference between gross primary production and respiration (NEP = GPP - R), it can be viewed as the net biological conversion of inorganic carbon to organic carbon (and vice versa), and can thus be determined through whole-lake mass balance of either inorganic or organic carbon. NEP assessed through inorganic (IC) or organic carbon (OC) can be estimated as:
where E is export of OC through fluvial transport and IC through fluvial transport and carbon gas (e.g. CO2, CH4) exchange between the lake surface to the atmosphere; S is storage in the lake sediments and water column for OC and water column for IC; and I is the input of OC and IC from fluvial, surrounding wetland, and airborne pathways (e.g. atmospheric deposition, litterfall). A lake that receives more OC from the watershed than it exports downstream or accumulates in the water column and sediments (Ioc > Eoc + Soc) indicates that there was net conversion of OC to IC within the lake and is thus net heterotrophic (negative NEP). Likewise, a lake that accumulates and exports more IC than was received from the watershed (Sic + Eic > Iic) also indicates net conversion of OC to IC within the lake and is thus net heterotrophic.
Benthic metabolism methods
Although the free-water method likely contains some benthic metabolic signal, isolating the benthic contribution to whole-lake metabolism requires benthic-specific methods. Analogous to the light and dark bottle methods described above, lake sediment cores can be collected and changes in dissolved oxygen or carbon fixation can be used to estimate rates of primary productivity and respiration. Relatively new methods describe isolating the sediment-water interface with transparent domes and measure changes in dissolved oxygen in-situ, which is a hybrid between the free-water method and light-dark bottle method. These in-situ benthic chamber methods allow for relatively easy multi-day estimate of benthic metabolism, which helps the researcher determine how benthic metabolism changes with varying weather patterns and lake characteristics.
Assumptions
Extrapolating site or depth specific measurements to the entire lake can be problematic as there can be significant metabolic variability both vertically and horizontally within a lake (see variability section). For example, many lake metabolism studies only have a single epilimnetic estimate of metabolism, however, this may overestimate metabolic characteristics about the lake such as NEP depending on the mixed layer depth to light extinction depth ratio. Averaging daily metabolism estimates over longer time periods may help overcome some of these single site extrapolation issues, but one must carefully consider the implications of the metabolic estimates and not over extrapolate measurements.
Relation to constituents
Organismal metabolic rate, or the rate at which organisms assimilate, transform, and expend energy, is influenced by a few key constituents, namely light, nutrients, temperature, and organic matter. The influence of these constituents on organismal metabolism ultimately governs metabolism at the whole-lake scale and can dictate whether a lake is a net source or sink of carbon. In the following section, we describe the relationship between these key constituents and organismal and ecosystem-level metabolism. Although relationships between organisms and constituents described here are well-established, interacting effects of constituents on metabolic rates from organisms to lake ecosystems makes predicting changes in metabolism across lakes or within lakes through time difficult. Many of these complex interacting effects will be discussed in the spatial and temporal variability section.
Temperature
Temperature is a strong controlling factor on biochemical reaction rates and biological activity. Optimal temperature varies across aquatic organisms as some organisms are more cold-adapted while others prefer warmer habitats. There are rare cases of extreme thermal tolerance in hypersaline antarctic lakes (e.g. Don Juan Pond) or hot springs (e.g. Fly Geyser); however, most lake organisms on Earth reside in temperatures ranging from 0 to 40 °C. Metabolic rates typically scale exponentially with temperature, however, the activation energy for primary productivity and respiration often differ, with photosynthesis having a lower activation energy than aerobic respiration. These differences in activation energies could have implications for net metabolic balance within lake ecosystems as the climate warms. For example, Scharfenberger et al. (2019) show that increasing water temperature resulting from climate change could switch lakes from being net autotrophic to heterotrophic due to differences in activation energy, however, the temperature at which they switch depends on the amount of nutrients available.
Nutrients
The amount of material available for assimilating into organismal cells controls the rate of metabolism at the cellular to lake ecosystem level. In lakes, phosphorus and nitrogen are the most common limiting nutrients of primary production and ecosystem respiration. Foundational work on the positive relationship between phosphorus concentration and lake eutrophication resulted in legislation that limited the amount of phosphorus in laundry detergents, among other regulations. Although phosphorus is often used as a predictor of lake ecosystem productivity and excess phosphorus as an indicator of eutrophication, many studies show that metabolism is co-limited by phosphorus and nitrogen or nitrogen alone. The balance between phosphorus, nitrogen, and other nutrients, termed ecological stoichiometry, can dictate rates of organismal growth and whole-lake metabolism through cellular requirements of these essential nutrients mediated by life-history traits. For example, fast-growing cladocerans have a much lower nitrogen to phosphorus ratio (N:P) than copepods, mostly due to the high amount of phosphorus-rich RNA in their cells used for rapid growth. Cladocerans residing in lakes with high N:P ratios relative to cladoceran body stoichiometry will be limited in growth and metabolism, having effects on whole-lake metabolism. Furthermore, cascading effects from food web manipulations can cause changes in productivity from changes to nutrient stoichiometry. For example, piscivore addition can reduce predation pressure on fast-growing, low N:P cladocerans which increase in population rapidly, retain phosphorus in their cells, and can cause a lake to become phosphorus limited, consequently reducing whole-lake primary productivity.
Light
Solar energy is required for converting carbon dioxide and water into organic matter, otherwise known as photosynthesis. As with temperature and nutrients, different algae have different rates of metabolic response to increasing light and also different optimal light conditions for growth, as some algae are more adapted for darker environments while others can outcompete in lighter conditions. Light can also interact with nutrients to affect species-specific algal productivity response to increasing light. These different responses at the organismal level propagate up to influence metabolism at the ecosystem level. Even in low-nutrient lakes where nutrients would be expected to be the limiting resource for primary productivity, light can still be the limiting resource, which has cascading negative effects on higher trophic levels such as fish productivity. Variability in light in different lake zones and within a lake through time creates patchiness in productivity both spatially and temporally.
In addition to controlling primary productivity, sunlight can also influence rates of respiration by partially oxidizing organic matter which can make it easier for bacteria to break down and convert into carbon dioxide. This partial photooxidation essentially increases the amount of organic matter that is available for mineralization. In some lakes, complete photooxidation or partial photooxidation can account for a majority of the conversion from organic to inorganic matter, however, the proportion to bacterial respiration varies greatly among lakes.
Organic carbon
Primary and secondary consumers in lakes require organic matter (either from plants or animals) to maintain organismal function. Organic matter including tree leaves, dissolved organic matter, and algae provide essential resources to these consumers and in the process increase lake ecosystem respiration rates in the conversion of organic matter to cellular growth and organismal maintenance. Some sources of organic matter may impact the availability of other constituents. For example, dissolved organic matter often darkens lake water which reduces the amount of light available in the lake, thus reducing primary production. However, increases in organic matter loading to a lake can also increase nutrients that are associated with the organic matter, which can stimulate primary production and respiration. Increased dissolved organic matter loading can create tradeoffs between increasing light limitation and release from nutrient limitation. This tradeoff can create non-linear relationships between lake primary production and dissolved organic matter loading based on how much nutrients are associated with the organic matter and how quickly the dissolved organic matter blocks out light in the water column. This is because at low dissolved organic matter concentrations as dissolved organic matter concentration increases, increased associated nutrients enhances GPP. But as dissolved organic matter continues to increase, the reduction in light from the darkening of the lake water suppresses GPP as light becomes the limiting resource for primary productivity. Differences in the magnitude and location of maximum GPP in response to increased DOC load are hypothesized to arise based on the ratio of DOC to nutrients coming into the lake as well as the effect of DOC on lake light climate. The darkening of the lake water can also change thermal regimes within the lake as darker waters typically mean that warmer waters remain at the top of the lake while cooler waters are at the bottom. This change in heat energy distribution can impact the rates of pelagic and benthic productivity (see Temperature above), and change water column stability, with impacts on vertical distribution of nutrients, therefore having effects on vertical distribution of metabolic rates.
Other constituents
Other lake constituents can influence lake metabolic rates including CO2 concentration, pH, salinity, and silica, among others. CO2 can be a limiting (or co-limiting along with other nutrients) resource for primary productivity and can promote more intense phytoplankton blooms. Some algal species, such as chrysophytes, may not have carbon-concentrating mechanisms or the ability to use bicarbonate as a source of inorganic carbon for photosynthesis, thus, elevated levels of CO2 may increase their rates of photosynthesis. During algal blooms, elevated dissolved CO2 ensures that CO2 is not a limiting resource for growth since rapid increases in production deplete CO2 and raise pH. Changes in pH at short time scales (e.g. sub-daily) from spikes in primary productivity may cause short-term reductions in bacterial growth and respiration, but at longer timescales, bacterial communities can adapt to elevated pH.
Salinity can also cause changes in metabolic rates of lakes through salinity impacts on individual metabolic rates and community composition. Lake metabolic rates can be correlated both positively or negatively with salinity due to interactions of salinity with other drivers of ecosystem metabolism, such as flushing rates or droughts. For example, Moreira-Turcq (2000) found that excess precipitation over evaporation caused reduced salinity in a coastal lagoon, increased nutrient loading, and increased pelagic primary productivity. The positive relationship between primary productivity and salinity might be an indicator of changes in nutrient availability due to increased inflows. However, salinity increases from road salts can cause toxicity in some lake organisms, and extreme cases of salinity increases can restrict lake mixing which could change distribution of metabolism rates throughout the lake water column.
Spatial and temporal variability
Metabolic rates in lakes and reservoirs are controlled by many environmental factors, such as light and nutrient availability, temperature, and water column mixing regimes. Thus, spatial and temporal changes in those factors cause spatial and temporal variability in metabolic rates, and each of those factors affect metabolism at different spatial and temporal scales.
Spatial variation within lakes
Variable contributions from different lake zones (i.e. littoral, limnetic, benthic) to whole lake metabolism depends mostly on patchiness in algal and bacterial biomass, and light and nutrient availability. In terms of the organisms contributing to metabolism in each of these zones, limnetic metabolism is dominated by phytoplankton, zooplankton, and bacterial metabolism, with low contribution from epiphytes and fish. Benthic metabolism can receive great contributions from macrophytes, macro- and microalgae, invertebrates, and bacteria. Benthic metabolism is usually highest in shallow littoral zones, or in clear-water shallow lakes, in which light reaches the bottom of the lake to stimulate primary production. In dark or turbid deep lakes, primary production may be restricted to shallower waters and aerobic respiration may be reduced or non-existent in deeper waters due to the formation of anoxic deep zones.
The degree of spatial heterogeneity in metabolic rates within a lake depends on lake morphometry, catchment characteristics (e.g. differences in land use throughout the catchment and inputs from streams), and hydrodynamic processes. For example, lakes with more intense hydrodynamic processes, such as strong vertical and lateral mixing, are more laterally and vertically homogeneous in relation to metabolic rates than highly stratified lakes. On the other hand, lakes with more developed littoral areas have greater metabolic heterogeneity laterally than lakes with a more circular shape and low proportions of shallow littoral areas.
Light attenuation occurring throughout the water column, in combination with thermal and chemical stratification and wind- or convective-driven turbulence, contribute to the vertical distribution of nutrients and organisms in the water column. In stratified lakes, organic matter and nutrients tend to be more concentrated at deeper layers, while light is more available at shallower layers. The vertical distribution of primary production responds to a balance between light and nutrient availability, while respiration occurs more independently of light and nutrients and more homogeneously with depth. This often results in strong coupling of gross primary production (GPP) and ecosystem respiration (ER) in lake surface layers but weaker coupling at greater depths. This means that ER rates are strongly dependent on primary production in shallower layers, while in deeper layers it becomes more dependent on a mixture of organic matter from terrestrial sources and sedimentation of algae particles and organic matter produced in shallower layers. In lakes with a low concentration of nutrients in surface waters and with light penetration below the mixed layer, primary production is higher in intermediate depths, where there is sufficient light for photosynthesis and higher nutrient availability. On the other hand, low transparent polymictic lakes have higher primary production on near-surface layers, usually with a net autotrophic balance (GPP > ER) between primary production and respiration.
Laterally, heterogeneity within lakes is driven by differences in metabolic rates in the open water limnetic zones and the more benthic-dominated littoral zones. Littoral areas are usually more complex and heterogeneous, in part because of their proximity with the terrestrial system, but also due to low water volume and high sediment-to-water volume ratio. Thus, littoral zones are more susceptible to changes in temperature, inputs of nutrients and organic matter from the landscape and river inflows, wind shear mixing and wave action, shading from terrestrial vegetation, and resuspension of the sediments (Figure 1). Additionally, littoral zones usually have greater habitat complexity due to the presence of macrophytes, which serve as shelter, nursery, and feeding place for many organisms. Consequently, metabolic rates in the littoral areas usually have high short-term variability and are typically greater than limnetic metabolic rates.
Spatial variation across lakes
In addition to spatial variability within lakes, whole-lake metabolic rates and their drivers also differ across lakes. Each lake has a unique set of characteristics depending on their morphometry, catchment properties, and hydrologic characteristics. These features affect lake conditions, such as water colour, temperature, nutrients, organic matter, light attenuation, vertical and horizontal mixing, with direct and indirect effects on lake metabolism.
As lakes differ in the status of their constituents (e.g. light, nutrients, temperature, and organic matter), there are emerging differences in the magnitude and variability of metabolic rates among lakes. In the previous section (Relation to Constituents), we discussed the expected patterns of metabolic rates in response to variability in these influential constituents. Here, we will discuss how whole-lake metabolism varies across lakes due to differences in these constituents as mediated by differences in lake morphometry, catchment properties, and water residence time.
Lake morphometry (e.g. lake size and shape) and catchment properties (e.g. land use, drainage area, climate, and geological characteristics) determine the flux of external inputs of organic matter and nutrients per unit of lake water volume. As the ratio between catchment size and lake water volume (drainage ratio) increases, the flux of nutrients and organic matter from the surrounding terrestrial landscape generally increases. That is, small lakes with relatively large catchments will receive more external inputs of nutrients and organic matter per unit of lake volume than large lakes with relatively small catchments, thus enhancing both primary production and respiration rates. In lakes with small drainage ratio (i.e. relative large lake surface area in relation to catchment area), metabolic processes are expected to be less dependent on external inputs coming from the surrounding catchment. Additionally, small lakes are less exposed to wind-driven mixing and typically have higher terrestrial organic matter input which often results in shallower mixing depths and enhanced light attenuation, thus limiting primary production to upper portions of small lakes. Considering lakes with similar catchment properties, small lakes are generally more net heterotrophic (GPP < ER) than large lakes, since their higher respiration rates are fueled by higher allochthonous organic matter (i.e. synthesized within the drainage area, but outside of the water body) entering the system and outpaces primary production which is limited to shallower lake layers.
Catchment properties, namely land cover, land use, and geologic characteristics, influence lake metabolism through their impact on the quality of organic matter and nutrients entering the lake as well as wind exposure. The organic matter quality can impact light attenuation, and along with wind exposure, can influence heat and light distribution throughout the water lake column. Lakes in landscapes dominated by agriculture have higher nutrient inputs and lower organic matter inputs compared to lakes with similar drainage ratio but in landscapes dominated by forests. Thus, lakes in agricultural-dominated landscapes are expected to have higher primary production rates, more algal blooms, and excessive macrophyte biomass compared to lakes in forest-dominated landscapes (Figure). However, the effects of catchment size and catchment type are complex and interactive. Relatively small forested lakes are more shaded and protected from wind exposure and also receive high amounts of allochthonous organic matter. Thus, small forested lakes are generally more humic with a shallow mixed layer and reduced light penetration. The high inputs of allochthonous organic matter (produced outside the lake) stimulate heterotrophic communities, such as bacteria, zooplankton, and fish, enhancing whole-lake respiration rates. Hence small forested lakes are more likely to be net heterotrophic, with ER rates exceeding primary production rates in the lake. On the other hand, forested lakes with low drainage ratio receive relatively less nutrients and organic matter, typically resulting in clear-water lakes, with low GPP and ER rates (Table). Another important difference among lakes that influences lake metabolism variability is the residence time of the water in the system, especially among lakes that are intensively managed by humans. Changes to lake level and flushing rates affects nutrient and organic matter concentrations, organism abundance, and rates of ecological processes such as photodegradation of colored organic matter, thus affecting metabolic rates magnitudes and variability. Endorheic lakes or lakes with intermediate hydraulic residence time (HRT) typically have a high retention time of nutrients and organic matter in the system, that favours growth of primary producers and bacterial degradation of organic matter. Thus, these types of lakes are expected to maintain relatively higher and less variable GPP and ER rates, than lakes with low residence time in the same trophic status. On the other hand, lakes with long HRT are expected to have reduced metabolic rates due to lower inputs of nutrients and organic matter to the lake. Finally, lentic systems that have frequent and intense changes in water level and accelerated flushing rates have a dynamic closer to lotic systems, with usually low GPP and ER rates, due to nutrients, organic matter, and algae being flushed out of the system during intense flushing events.
Temporal variation on a daily scale
On a daily scale, GPP rates are most affected by the diel cycle of photosynthetically active radiation while ER is largely affected by changes in water temperature. Additionally, ER rates are also tied to the quantity or quality of the organic substrate and relative contributions of autotrophic and heterotrophic respiration, as indicated by studies of the patterns of night-time respiration (e.g. Sadro et al. 2014). For example, bacterioplankton respiration can be higher during the day and in the first hours of the night, due to the higher availability of labile dissolved organic matter produced by phytoplankton. As the sun rises, there is a rapid increase in primary production in the lake, often making it autotrophic (NEP > 0) and reducing dissolved that was produced from carbon mineralization that occurred during the night. This behavior continues until reaching a peak in NEP, typically around the maximum light availability. Then there is a tendency for the NEP to fall steadily between the hours of maximum light availability until the next day's sunrise.
Day-to-day differences in incoming light and temperature, due to differences in the weather, such as cloud cover and storms, affect rates of primary production and, to a lesser extent, respiration. These weather variations also cause short-term variability in mixed layer depth, which in turn affects nutrients, organic matter, and light availability, as well as vertical and horizontal gas exchanges. Deep mixing reduces light availability but also increases nutrients and organic matter availability in the upper layers. Thus the effects of short-term variability in mixed layer depth on gross primary production (GPP) will depend on which are the limiting factors on each lake at a given period. Thus a deeper mixing layer could either increase or decrease GPP rates depending on the balance between nutrient and light limitation of photosynthesis (Figure).
Responses in metabolic rates are as dynamic as the physical and chemical processes occurring in the lake, but changes in algal biomass are less variable, involving growth and loss over longer periods. High light and nutrients availability are associated with the formation of algal blooms in lakes; during these blooms GPP rates are very high, and ER rates usually increase almost as much as GPP rates, and the balance of GPP and ER is close to 1. Right after the bloom, GPP rates start to decrease but ER rates continue higher due to the high availability of labile organic matter, which can lead to a fast depletion of dissolved oxygen concentration in the water column, resulting in fish kills.
Temporal variation on an annual scale
Seasonal variations in metabolism can be driven by seasonal variations in temperature, ice-cover, rainfall, mixing and stratification dynamics, and community succession (e.g. phytoplankton control by zooplankton). Seasonal variations in lake metabolism will depend on how seasons alter the inputs of nutrients and organic matter, and light availability, and on which factors are limiting metabolic rates in each lake.
Light is a primary driver of lake metabolism, thus seasonality in light levels is an important driver of seasonal changes in lake metabolic rates. Therefore, it is expected GPP rates to be more pronounced during seasons such as spring and summer, in which light levels are higher and days are longer. This is especially pronounced for lakes with light-limited GPP, for example, more turbid or stained lakes. Seasonality in light levels also affects ER rates. Ecosystem respiration rates are usually coupled with GPP rates, thus seasons with higher GPP will also show higher ER rates associated with increased organic matter produced within the lake. Moreover, during seasons with higher light levels photodegradation of organic matter is more pronounced, which stimulates microbial degradation, enhancing heterotrophic respiration rates. Most of the lakes in the world freeze during the winter, a low-irradiance period, in which ice and snow cover limit light penetration in the water column. Light limitation occurs mainly by snow cover and not by ice, which makes primary production strongly sensitive to snow cover in those lakes. In addition to light limitation, low temperatures under ice also diminish metabolic rates, but not enough to cease metabolic processes. Therefore, the metabolic balance is usually negative during the majority of the ice season, leading to dissolved oxygen depletion. Shallow lakes in arid climates have none or very little snow cover during the winter, thus, primary production sustained under-ice can be enough to prevent dissolved oxygen depletion, as reported by Song and others in a Mongolian lake. Despite the high proportion of the world's lakes that freeze during the winter, few studies have been conducted on lake metabolism under-ice, mostly due to sampling technical difficulties.
Lakes that are closer to the equator experience less seasonality regarding light intensity and daylight hours than lakes at higher latitudes (temperate and polar zones). Thus, lakes at higher latitudes are more likely to experience light limitation of primary production during low-light seasons (winter and autumn). Seasonal differences in temperature are also not so important in the tropics as they are for higher latitudes lakes. Thus, the direct effect of temperature seasonal variations on metabolic rates is more important in higher latitudes lakes than in tropical lakes (Figure). In turn, tropical and subtropical lakes are more likely to have seasonal variations following the stratification and mixing dynamics, and rainfall regimes (wet and dry seasons), than due to the four astronomical or meteorological seasons (spring, summer, autumn, and winter) when compared to higher latitudes lakes. Seasonal changes in temperature and rainfall lead to seasonal changes in water column stability. During periods of low water column stability, a deeper mixed layer (total or partial mixing of the water column, depending on the lake) increases the inputs of nutrients and organic matter from deeper layers and through sediment resuspension, which reduce light availability. Conversely, during periods of strong water column stability, internal loadings of nutrients, organic matter, and the associated bacteria to the water column are suppressed, while algal loss due to sinking is enhanced. Moreover, light availability during this period is higher, due to photobleaching, lower resuspension of sediments, and lower mixing depth, which expose phytoplankton to a more light-rich environment. Higher ER rates during low water column stability period, as a consequence of higher organic matter availability and higher bacteria biomass associated with this organic matter, have been reported for many lakes around the world. However, primary production rates responses to these seasonal changes have been shown different behaviors in different lakes. As said before, the responses of metabolic rates to those changes will depend on limiting factors of primary production in each lake (Figure). During low water column stability periods, upwelling of waters rich in nutrients can result in higher pelagic GPP rates, as has been observed in some tropical lakes. Conversely, during low water column stability periods, GPP rates can be limited by low light availability, as have been observed in some temperate and subtropical lakes. The net metabolic balance is usually more negative during de-stratified periods, even in lakes in which the well-mixed season is the most productive period. Regardless of the high GPP in these systems, ER rates are also enhanced by the increased availability of organic matter stocks from sediments and deeper waters.
Seasonal differences in rainfall also affect metabolic rates. The increase in precipitation promotes the entry of organic matter and nutrients in lakes, which can stimulate ER rates and stimulate or inhibit GPP rates, depending on the balance between increased nutrients and lower light availability. On the other hand, lower precipitation also affects limnological conditions by reducing the water level and, thereby, increasing the concentration of nutrients and chlorophyll, as well as changing the thermal stability of aquatic environments. These changes could also enhance ER and GPP rates. Thus, the degree of the responses of metabolic rates to seasonal changes in rainfall will depend on lake morphometry, catchment properties and the intensity and duration of the rainfall events. Lakes frequently exposed to strong storms, such as the typhoon areas in the Northwest Pacific Ocean, receive intense rainfall events that can last for a few days. During these storm seasons, a reduction in metabolic rates is expected due to reduced sunlight and flushing of water and organisms. This reduction is expected to be more pronounced in GPP than in ER rates, resulting in a more heterotrophic NEP (GPP < ER). In a subtropical lake in Taiwan, for example, a decoupling of GPP and ER rates was observed during typhoon seasons, following a shift in the organic matter pool from autochthonous-based (organic matter produced within the lake) to allochthonous-based (organic matter produced outside the lake). This suggests that ER rates were more resistant to the typhoon disturbance than GPP rates.
Interannual variations
Interannual variability on metabolic rates can be driven by extensive changes in the catchment or by directional and cyclical climate change and climate disturbances, such as the events associated with the El Niño Southern Oscillation (ENSO). Those changes in the catchment, air temperature, and precipitation between years affect metabolic rates by altering nutrient and organic matter inputs to the lake, light attenuation, mixing dynamics, and by direct temperature-dependence of metabolic processes.
The increase in precipitation increases external loading of organic matter, nutrients and sediments in lakes. Moreover, increased discharge events promoted by increased rainfall can also alter mixing dynamics and cause physical flushing of organisms. While lower precipitation associated with high evaporation rates also affects limnological conditions by reducing the water level and thereby increasing the concentration of nutrients and chlorophyll, as well as changing the thermal stability of aquatic environments. During warmer years, a stronger water column stability limits the inputs of nutrients and organic matter to the photic zone. In contrast, during colder years, a less stable water column enhances resuspension of the sediments and the inputs of nutrients and organic matter from deeper waters. This lowers light availability, while enhances nutrient and organic matter availability. Thus, the effects of differences in precipitation and temperature between years in metabolic rates will depend on the intensity and duration of these changes, and also in which factors are limiting GPP and ER in each water body.
In lakes with nutrients and organic matter limitation of GPP and ER, wetter years can enhance GPP and ER rates, due to higher inputs of nutrients and organic matter from the landscape. This will depend if the terrestrial inputs will be promptly available for the primary producers and heterotrophic communities or if it is going to enter the lake through deeper waters, in which metabolic processes are very low or non-existent. In this case, the inputs will only be available in the next water column mixing event. Thus, increases in metabolic rates due to rainfall depend also on the stratification and mixing dynamics, hydrology, and morphometry of the lake. On the other hand, drier years can also have enhanced GPP and ER rates if it is accompanied by lower water levels, which would lead to higher nutrients and organic matter concentrations. A lower water level is associated with a less stable water column and higher proximity with the sediments, thus increased inputs of nutrients and organic matter from deeper waters. Also, a reduction in water level through water evaporation leads to a concentration effect. In turn, during warmer years the water column is more stable, and the depth of the mixing layer is shallower, thus reducing internal inputs of nutrients and organic matter to the mixed layer. Metabolic rates, in this scenario, will be lower in the upper mixed layer. In lakes with a photic zone extending deeper than the mixed layer, metabolic rates will be higher in intermediated depths, coinciding with the deep chlorophyll maxima.
In lakes with primary production limited mostly by light availability, increases in rainfall could lead to lower light availability, associated with increased dissolved organic matter and total suspended matter. Consequently, increased rainfall would be associated with lower levels of GPP, which would reduce respiration rates associated with autochthonous production, leading to a decoupling of GPP and ER rates. In addition, increased allochthonous organic matter availability during wet years can lead to higher ER, and consequently leading the metabolic balance to be negative (NEP <0).
Changes in annual precipitation can also affect the spatial variability in metabolic rates within lakes. Williamson and collaborators, for example, found that, in a hyper-eutrophic reservoir in North America, the relative spatial variability in GPP and ER rates were higher in a dry year compared to a wet one. These suggest higher relevance of internal processes, such as internal loading, nutrient uptake, sedimentation, and resuspension, to metabolic rates during dry years.
See also
Stream metabolism
Ecosystem model
Catabolism
Apparent oxygen utilisation
References
Lakes
Limnology
Limnology and Oceanography articles
Metabolism
Aquatic ecology | Lake metabolism | [
"Chemistry",
"Biology",
"Environmental_science"
] | 8,512 | [
"Hydrology",
"Lakes",
"Ecosystems",
"Cellular processes",
"Biochemistry",
"Aquatic ecology",
"Metabolism"
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59,168,504 | https://en.wikipedia.org/wiki/Developmental%20bias | In evolutionary biology, developmental bias refers to the production against or towards certain ontogenetic trajectories which ultimately influence the direction and outcome of evolutionary change by affecting the rates, magnitudes, directions and limits of trait evolution. Historically, the term was synonymous with developmental constraint, however, the latter has been more recently interpreted as referring solely to the negative role of development in evolution.
The role of the embryo
In modern evolutionary biology, the idea of developmental bias is embedded into a current of thought called Structuralism, which emphasizes the role of the organism as a causal force of evolutionary change. In the Structuralist view, phenotypic evolution is the result of the action of natural selection on previously ‘filtered’ variation during the course of ontogeny. It contrasts with the Functionalist (also “adaptationist”, “pan-selectionist” or “externalist”) view in which phenotypic evolution results only from the interaction between the deterministic action of natural selection and variation caused by mutation.
The rationale behind the role of the organism, or more specifically the embryo, as a causal force in evolution and for the existence of bias is as follows: The traditional, neo-Darwinian, approach to explain the process behind evolutionary change is natural selection acting upon heritable variation caused by genetic mutations. However, natural selection acts on phenotypes and mutation does not in itself produce phenotypic variation, thus, there is a conceptual gap regarding the connection between a mutation and the potential change in phenotype. For a mutation to readily alter a phenotype, and hence be visible to natural selection, it has to modify the ontogenetic trajectory, a process referred to as developmental reprogramming. Some kinds of reprogramming are more likely to occur than others given the nature of the genotype–phenotype map, which determines the propensity of a system to vary in a particular direction, thus, creating a bias. In other words, the underlying architecture of the developmental systems influences the kinds of possible phenotypic outcomes.
However, developmental bias can evolve through natural selection, and both processes simultaneously influence phenotypic evolution. For example, developmental bias can affect the rate or path to an adaptive peak (high-fitness phenotype), and conversely, strong directional selection can modify the developmental bias to increase the phenotypic variation in the direction of selection.
Types of bias
Developmental constraints
Developmental constraints are limitations on phenotypic variability (or absence of variation) caused by the inherent structure and dynamics of the developmental system. Constraints are a bias against a certain ontogenetic trajectory, and consequently are thought to limit adaptive evolution.
Developmental drive
Developmental drive is the inherent natural tendency of organisms and their ontogenetic trajectories to change in a particular direction (i.e. a bias towards a certain ontogenetic trajectory). This type of bias is thought to facilitate adaptive evolution by aligning phenotypic variability with the direction of selection.
Distribution of phenotypic variation
Morphospace
The morphospace is a quantitative representation of phenotypes in a multidimensional space, where each dimension corresponds to a trait. The phenotype of each organism or species is then represented as a point in that space that summarizes the combination of values or states at each particular trait. This approach is used to study the evolution of realized phenotypes compared to those that are theoretically possible but inexistent.
Nonrandom (anisotropic) distribution of phenotypic variation
Describing and understanding the drivers of the distribution of phenotypic variation in nature is one of the main goals in evolutionary biology. One way to study the distribution of phenotypic variation is through depicting the volume of the morphospace occupied by a set of organisms or species. Theoretically, there can exist a natural process that generates an almost-evenly (quasi stochastic) distributed pattern of phenotypes in the morphospace, regarding that new species necessary tend to occupy a point in the morphospace that is close to those of its phylogenetic relatives. However, it is now widely acknowledged that organisms are not evenly distributed along the morphospace, i.e. isotropic variation, but instead are nonrandomly distributed, i.e. anisotropic variation. In other words, there exists a discordance between the apparent (or theoretical) possible phenotypes and their actual accessibility.
Thus, some phenotypes are inaccessible (or impossible) due to the underlying architecture of the developmental trajectory, while others are accessible (or possible). However, of the possible phenotypes, some are ‘easier’ or more probable to occur than others. For example, a phenotype such as the classical figure of a dragon (i.e. a giant reptile-like creature with two pairs of limbs and an anterior pair of wings) may be impossible because in vertebrates the fore-limbs and the anterior pair of wings are homologous characters (e.g. birds and bats), and, thus, are mutually exclusive. On the other hand, if two phenotypes are possible (and equally fit), but one form of reprogramming requires only one mutation while the other requires two or more, the former will be more likely to occur (assuming that genetic mutations occur randomly).
An important distinction between structuralism and functionalism regards primarily with the interpretation of the causes of the empty regions in the morphospace (that is, the inexistent phenotypes): Under the functionalist view, empty spaces correspond to phenotypes that are both ontogenetically possible and equally probable but are eliminated by natural selection due to their low fitness. In contrast, under the structuralist view, empty spaces correspond to ontogenetically impossible or improbable phenotypes, thus, implying a bias in the types of phenotypes that can be produced assuming equal amounts of variation (genetic mutations) in both models.
Classical examples of anisotropic variation
In a classical natural example of bias it was shown that only a small proportion of all possible snail shell shapes was realized in nature and actual species were confined to discrete regions of the shell-morphospace rather than being continuously distributed. In another natural example, it was shown that soil-dwelling centipedes have an enormous variation in the number of pairs of legs, the lowest being 27 and the highest 191 pairs; however, there are no species with an even number of leg pairs, which suggests that either these phenotypes are somehow restricted during development or that there is a developmental drive into odd numbers.
A study of the polydactyl toe counts of 375 Hemingway mutants of the Maine Coon cat showed that the number of additional toes was variable (plastic) and contained a bias. The Maine Coon cat (as the basic model of the Hemingway mutants) has 18 toes in the wild. Polydactyly occurred in some cases with an unchanged number of toes (18 toes), whereby the deviation consisted of a three-jointed thumb due to the extension of the first toe. However, 20 toes were found much more frequently and then 22, 24 or 26 toes with decreasing frequency. Odd total numbers of toes on the feet were less common. There is another bias between the number of toes on the front and rear feet, and a left-right asymmetry in the number of toes. Random bistability during the development process could explain the observed bias.
Conversely, developmental abnormalities (or teratologies) have been used to understand the logic behind the mechanisms that produce variation. For example, in a wide range of animals, from fish to humans, two-headed organisms are much more common than three-headed organisms; similarly, Siamese twins theoretically could ‘fuse’ through any region in the body but the fusion occurs more frequently in the abdominal region. This trend was referred to as transpecific parallelism, suggesting the existence of profound historical rules governing the expression of abnormal forms in distantly related species.
Biased phenotypes I: Continuous variation
Developmental integration and the P-matrix
Integration or covariation among traits during development has been suggested to constrain phenotypic evolution to certain regions of the morphospace and limit adaptive evolution. These allometric changes are widespread in nature and can account for a wide variety of realized morphologies and subsequent ecological and physiological changes. Under this approach, phenotype is seen as an integrated system where each trait develops and evolves in concert with the other traits, and thus, a change in one trait affects the interacting parts in a correlated manner. The correlation between traits is a consequence of the architecture of the genotype–phenotype map, particularly the pleiotropic effects of underlying genes. This correlated change between traits can be measured and analyzed through a phenotypic variance-covariance matrix (P-matrix) which summarizes the dimensions of phenotypic variability and the main axis of variation.
Quantitative genetics and the G-matrix
Quantitative genetics is a statistical framework mainly concerned with modeling the evolution of continuous characters. Under this framework, correlation between traits could be the result of two processes: 1) natural selection acting simultaneously on several traits ensuring that they are inherited together (i.e. linkage disequilibrium), or 2) natural selection acting on one trait causing correlated change in other traits due to pleiotropic effects of genes. For a set of traits, the equation that describe the variance among traits is the multivariate breeder’s equation Δz = β x G, where Δz is the vector of differences in trait means, β is a vector of selection coefficients, and G is a matrix of the additive genetic variance and covariance between traits. Thus, a population’s immediate ability to respond to selection is determined by the G-matrix, in which the variance is a function of standing genetic variation, and the covariance arises from pleiotropy and linkage disequilibrium. Although the G-matrix is one of the most relevant parameters to study evolvability, the mutational matrix (M-matrix), also known as the distribution of mutational effects, has been shown to be of equivalent importance. The M-matrix describes the potential effects of new mutations on the existing genetic variances and covariances, and these effects will depend on the epistatic and pleiotropic interactions of the underlying genes. In other words, the M-matrix determines the G-matrix, and thus, the response to selection of a population. Similarly to the P-matrix, the G-matrix describes the main axis of variation.
Paths of least resistance
A general consequence of the P-matrices and G-matrices is that evolution will tend to follow the ‘path of least resistance’. In other words, if the main axis of variation is aligned with the direction of selection, covariation (genetic or phenotypic) will facilitate the rate of adaptive evolution; however, if the main axis of variation is orthogonal to the direction of selection, covariation will constraint the rate of adaptive evolution. In general, for a population under the influence of a single fitness optimum, the rate of morphological divergence (from an ancestral to a new phenotype or between pairs of species) is inversely proportional to the angle formed by the main axis of variation and the direction of selection, causing a curved trajectory through the morphospace.
From the P-matrix for a set of characters, two broadly important measures of the propensity of variation can be extracted: 1) Respondability: ability of a developmental system to change in any direction, and 2) Evolvability: ability of a developmental system to change in the direction of natural selection. In the latter, the main axis of phenotypic variation is aligned with the direction of selection. Similarly, from the G-matrix, the most important parameter that describes the propensity of variation is the lead eigenvector of G (gmax), which describes the direction of greatest additive genetic variance for a set of continuous traits within populations. For a population undergoing directional selection, gmax will bias the main direction of the trajectory.
Biased phenotypes II: Properties of gene regulatory networks
Hierarchy and optimal pleiotropy
GRNs are modular, multilayered, and semi-hierarchically systems of genes and their products: each transcription factor provides multiple inputs to other genes, creating a complex array of interactions, and information regarding the timing, place and amount of gene expression generally flows from few high-level control genes through multiple intermediate genes to peripheral gene batteries that ultimately determine the fate of each cell. This type of architecture implies that high-level control genes tend to be more pleiotropic affecting multiple downstream genes, whereas intermediate and peripheral genes tend to have moderate to low pleiotropic effects, respectively.
In general, it is expected that newly arisen mutations with higher dominance and fewer pleiotropic and epistatic effects are more likely to be targets of evolution, thus, the hierarchical architecture of developmental pathways may bias the genetic basis of evolutionary change. For instance, genes within GRNs with "optimally pleiotropic" effects, that is, genes that have the most widespread effect on the trait under selection but few effects on other traits, are expected to accumulate a higher proportion of mutations that cause evolutionary change. These strategically-positioned genes have the potential to filter random genetic variation and translate it to nonrandom functionally integrated phenotypes, making adaptive variants effectively accessible to selection, and, thus, many of the mutations contributing to phenotypic evolution may be concentrated in these genes.
Neutral networks
The genotype–phenotype map perspective establishes that the way in which genotypic variation can be mapped to phenotypic variation is critical for the ability of a system to evolve. The prevalence of neutral mutations in nature implies that biological systems have more genotypes than phenotypes, and a consequence of this "many-to-few" relationship between genotype and phenotype is the existence of neutral networks. In development, neutral networks are clusters of GRNs that differ in only one interaction between two nodes (e.g. replacing transcription with suppression) and yet produce the same phenotypic outcome. In this sense, an individual phenotype within a population could be mapped to several equivalent GRNs, that together constitute a neutral network. Conversely, a GRN that differs in one interaction and causes a different phenotype is considered non-neutral. Given this architecture, the probability of mutating from one phenotype to another will depend on the number of neutral-neighbors relative to non-neutral neighbors for a particular GRN, and thus, phenotypic change will be influenced by the position of a GRN within the network and will be biased towards changes that require few mutations to reach a neighboring non-neutral GRN.
See also
Evolvability
Speciation
References
Further reading
Ontogeny and Phylogeny (Gould, 1977)
Biased Embryos and Evolution (Arthur, 2004)
Evolution: A developmental approach (Arthur, 2010)
Homology, Genes, and Evolutionary Innovation (Wagner, 2014)
Evolution, development, and the predictable genome (Stern, 2011)
Developmental biology
Extended evolutionary synthesis | Developmental bias | [
"Biology"
] | 3,161 | [
"Behavior",
"Developmental biology",
"Reproduction"
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59,171,520 | https://en.wikipedia.org/wiki/Schradan | Schradan, named after Gerhard Schrader, is an obsolete organophosphate insecticide. Schradan itself is a weak cholinesterase inhibitor and requires metabolic activation to become active.
See also
Dimefox
Mipafox
References
Acetylcholinesterase inhibitors
Organophosphate insecticides | Schradan | [
"Chemistry"
] | 66 | [
"Organic compounds",
"Organic compound stubs",
"Organic chemistry stubs"
] |
59,174,283 | https://en.wikipedia.org/wiki/List%20of%20higher%20virus%20taxa | This is a list of biological virus upper-level taxa. See also Comparison of computer viruses
This is an alphabetical list of biological virus higher taxa. It includes those taxa above family, ranging from realm to suborder, that are included in the ICTV's 2020 taxonomy release.
For a list of individual species, see List of virus species.
For a list of virus genera, see List of genera of viruses.
For a list of family-level viral taxa, see List of virus families and subfamilies.
Realms
Adnaviria
Duplodnaviria
Monodnaviria
Riboviria
Ribozyviria
Varidnaviria
Kingdoms
Bamfordvirae
Heunggongvirae
Helvetiavirae
Loebvirae
Orthornavirae
Pararnavirae
Sangervirae
Shotokuvirae
Trapavirae
Zilligvirae
Phyla and subphyla
Phyla
Ambiviricota
Artverviricota
Cossaviricota
Cressdnaviricota
Dividoviricota
Duplornaviricota
Hofneiviricota
Kitrinoviricota
Lenarviricota
Negarnaviricota
Nucleocytoviricota
Peploviricota
Phixviricota
Pisuviricota
Preplasmiviricota
Saleviricota
Taleaviricota
Uroviricota
Subphyla
Haploviricotina
Polyploviricotina
Classes
Alsuviricetes
Amabiliviricetes
Arfiviricetes
Caudoviricetes
Chrymotiviricetes
Chunqiuviricetes
Duplopiviricetes
Ellioviricetes
Faserviricetes
Flasuviricetes
Herviviricetes
Howeltoviricetes
Huolimaviricetes
Insthoviricetes
Laserviricetes
Leviviricetes
Malgrandaviricetes
Magsaviricetes
Maveriviricetes
Megaviricetes
Miaviricetes
Milneviricetes
Monjiviricetes
Mouviricetes
Naldaviricetes
Papovaviricetes
Pisoniviricetes
Pokkesviricetes
Polintoviricetes
Quintoviricetes
Repensiviricetes
Resentoviricetes
Revtraviricetes
Stelpaviricetes
Suforviricetes
Tectiliviricetes
Tokiviricetes
Tolucaviricetes
Vidaverviricetes
Yunchangviricetes
Orders and suborders
Orders
Algavirales
Amarillovirales
Articulavirales
Asfuvirales
Baphyvirales
Belfryvirales
Blubervirales
Bunyavirales
Caudovirales
Chitovirales
Cirlivirales
Cremevirales
Cryppavirales
Crytulvirales
Durnavirales
Geplafuvirales
Ghabrivirales
Goujianvirales
Halopanivirales
Haloruvirales
Hepelivirales
Herpesvirales
Imitervirales
Jingchuvirales
Kalamavirales
Lefavirales
Ligamenvirales
Martellivirales
Mindivirales
Mononegavirales
Mulpavirales
Muvirales
Nidovirales
Nodamuvirales
Norzivirales
Ortervirales
Orthopolintovirales
Ourlivirales
Patatavirales
Petitvirales
Piccovirales
Picornavirales
Pimascovirales
Polivirales
Priklausovirales
Primavirales
Recrevirales
Reovirales
Rowavirales
Sepolyvirales
Serpentovirales
Sobelivirales
Stellavirales
Timlovirales
Tolivirales
Tubulavirales
Tymovirales
Vinavirales
Wolframvirales
Zurhausenvirales
Suborders
Abnidovirineae
Arnidovirineae
Cornidovirineae
Mesnidovirineae
Monidovirineae
Nanidovirineae
Ronidovirineae
Tornidovirineae
See also
Virus
Virology
Virus classification
WikiSpecies:Virus
Wikipedia:WikiProject Viruses
List of virus species
List of virus genera
List of virus taxa
References
External links
ICTV
Master Species Lists at International Committee on Taxonomy of Viruses (ICTV) | List of higher virus taxa | [
"Biology"
] | 880 | [
"Viruses",
"Lists of viruses"
] |
59,176,229 | https://en.wikipedia.org/wiki/Solomon%20Museum | The Solomon Museum () is a museum in the Albanian city of Berat devoted to the history of the Jewish community in Albania.
History
Opened in 2018 by Professor Simon Vrusho, who ran it with his own pension and small donations, the museum was on the brink of closure after Vrusho passed away. However, Gazmend Toska, a French-Albanian businessperson, read about the museum and its possible fate, and paid for the relocation of the museum to a larger place in the city, which relocation took place on September 29, 2019. The museum is unique among its peers for telling the stories of how Albanians saved almost 2,000 Jews from the Holocaust, following their centuries-old Besa code of honor.
Collections
The museum has documents, photos, and items that have belonged to the Jewish community, which arrived in Berat in the 16th century from Spain, fleeing the Inquisition. Albania is the only Nazi-occupied territory whose Jewish population increased during World War II. The museum's current director is Angjelina Vrusho, Simon Vrusho's wife.
References
Jewish museums
Jews and Judaism in Albania
E
Ethnographic museums in Albania
Tourist attractions in Berat
Rescue of Jews during the Holocaust
Museums in Berat | Solomon Museum | [
"Biology"
] | 254 | [
"Rescue of Jews during the Holocaust",
"Behavior",
"Altruism"
] |
59,179,433 | https://en.wikipedia.org/wiki/He%20Jiankui | He Jiankui (; ; born 1984) is a Chinese biophysicist. He was named as the inaugural director of the Institute of Genetic Medicine at Wuchang Technical College, a private undergraduate college in Wuhan, in September 2023. Before January 2019, He served as associate professor at the Department of Biology of the Southern University of Science and Technology (SUSTech) in Shenzhen, Guangdong, China. Earning a PhD from Rice University in Texas on protein evolution, including that of CRISPR, He learned gene-editing techniques (CRISPR/Cas9) as a postdoctoral researcher at Stanford University in California.
In November 2018, He announced that he had created the first human genetically edited babies, twin girls who were born in mid-October 2018 and known by their pseudonyms, Lulu and Nana. The announcement was initially praised in the press as a major scientific advancement. But following scrutiny on how the experiment was executed, He received widespread condemnation. His research activities were suspended by the Chinese authorities on 29 November 2018, and he was fired by SUSTech on 21 January 2019. On 30 December 2019, a Chinese district court found He Jiankui guilty of illegal practice of medicine, sentencing him to three years in prison with a fine of 3 million yuan. He was released from prison in April 2022.
He was listed as one of Time 100 most influential people of 2019, in the section "Pioneers". At the same time he was variously referred to as a "rogue scientist", "China's Dr. Frankenstein", and a "mad genius".
Early life and education
He was born in Xinhua County, Loudi City, Hunan, in 1984.
He Jiankui attended the University of Science and Technology of China for undergraduate studies from 2002 to 2006, and graduated with a major in modern physics in 2006. He entered Rice University in 2007 and received a Doctor of Philosophy degree in biophysics under the supervision of Michael W. Deem in 2010.
After receiving his doctorate, Michael Deem arranged for He to work on CRISPR/Cas9 gene-editing technique as a postdoc fellow with Stephen Quake at Stanford University.
Career
In 2011, He received the Chinese Government Award for Outstanding Self-financed Students Abroad while still in the United States. Responding to an ad, He returned to China in 2012 under the city of Shenzhen's Peacock Plan and opened a lab at the Southern University of Science and Technology (SUSTech). As part of the program, he was given 1 million yuan (about US$ in 2012) in angel funding, which he used to start biotech and investment companies. He founded Direct Genomics in 2012 in Shenzhen, to develop single-molecule sequencing devices based on patents invented by Quake that had formerly been licensed by Helicos Biosciences. Direct Genomics received 40 million yuan (about US$ in 2012) in subsidies from Shenzhen, and raised hundreds of millions yuan more in private investment, but He sold his stake in 2019. He also founded Vienomics Biotech, which offers genome sequencing services for people with cancer. In 2017, He was included in the Chinese government's Thousand Talents Plan. He Jiankui's achievements were widely revered in Chinese media, including China Central Television and the People's Daily which covered his research and described him as "the founding father of third-generation genome editing" during a program celebrating the 19th National Congress of the Chinese Communist Party.
In August 2018, He met with Chinese-American doctor John Zhang to discuss plans to launch a company focused on "genetic medical tourism." The business was to target elite customers, operating out of China or Thailand. The business plans were shelved with He's detainment in November 2018.
He took an unpaid leave from SUSTech starting in February 2018, and began conducting the genome-editing clinical experiment. On 26 November 2018, he announced the birth of gene-edited human babies, Lulu and Nana. Three days later, on 29 November 2018, Chinese authorities suspended all of his research activities, saying that his work was "extremely abominable in nature" and a violation of Chinese law. In December 2018, following public outcry regarding his work, He appeared to have gone missing. SUSTech denied the widespread rumors that he had been detained. On 30 December 2019, the Shenzhen Nanshan District People's Court sentenced He Jiankui to three years in prison and a fine of three million yuan (about US$ in 2019). He Jiankui was released in April 2022 after serving the term.
Research
In 2010, at Rice University, He Jiankui and Michael W. Deem published a paper describing some details of the CRISPR protein; this paper was part of the early work on the CRISPR/Cas9 system, before it had been adopted as a gene editing tool.
In 2017, He gave a presentation at Cold Spring Harbor Laboratory describing work he did at Southern University of Science and Technology (SUSTech), in which he used CRISPR/Cas9 on mice, monkeys, and around 300 human embryos.
In January 2019, scientists in China reported the creation of five identical cloned gene-edited monkeys, using the same cloning technique that was used with Zhong Zhong and Hua Hua – the first ever cloned monkeys - and Dolly the sheep, and the same gene-editing CRISPR/Cas9 technique allegedly used by He in creating the first ever gene-modified human babies Lulu and Nana. The monkey clones were made in order to study several medical diseases.
Human gene-editing experiment
On 25 November 2018, He Jiankui first announced on YouTube that his team successfully created the world's first genome-edited babies, Lulu and Nana. Formally presenting the story at the Second International Summit on Human Genome Editing at the University of Hong Kong (HKU) three days later, he said that the twins were born from genetically modified embryos that were made resistant to M-tropic strains of HIV. His team recruited 8 couples consisting each of HIV-positive father and HIV-negative mother through Beijing-based HIV volunteer group called Baihualin China League. During in vitro fertilization, the sperms were cleansed of HIV. Using CRISPR/Cas9 gene-editing, they introduced a natural mutation CCR5-Δ32 in gene called CCR5, which would confer resistance to M-tropic HIV infection. The People's Daily announced the result as "a historical breakthrough in the application of gene editing technology for disease prevention".
The experiment had recruited couples who wanted to have children; in order to participate, the man had to be HIV-positive and the woman uninfected. At the time, it was not disclosed whether the clinical experiment had received appropriate ethical review from an institutional review board before it started, and it was unclear if the participants had given truly informed consent.
He Jiankui said that he edited the genomes of the embryos using CRISPR/Cas9, specifically targeting a gene, CCR5, that codes for a protein that HIV-1 uses to enter cells. He was trying to create a specific mutation in the gene, (CCR5 Δ32), that few people naturally have and that possibly confers innate resistance to HIV-1, as seen in the case of the Berlin Patient. He said that the girls still carried functional copies of CCR5 along with disabled CCR5 given mosaicism inherent in the present state of the art in germ-line editing. There are forms of HIV which use a different receptor instead of CCR5, and the work that He did could not protect resulting children from those forms of HIV.
He Jiankui said he used a preimplantation genetic diagnosis process on the embryos that were edited, where 3 to 5 single cells were removed and the editing was checked. He said that parents were offered the choice of using edited or unedited embryos.
The twin girls were born by mid-October 2018, according to emails from He to an adviser. According to He, they appeared to be healthy in all respects. When they were born, it was unclear if there might be long-term effects from the gene-editing; He was asked about his plans to monitor the children, and pay for their care should any problems arise, and how their confidentiality and that of their parents could remain protected. The names of the children used in reports, "Lulu" and "Nana", along with the names of their parents, "Mark" and "Grace", are pseudonyms. In February 2019, his claims were reported to have been confirmed by Chinese investigators, according to NPR News.
He Jiankui also said at the Hong Kong meeting that a second mother in his clinical experiment was in the early stages of pregnancy. Although there are no official reports, the baby was expected around August 2019, and the birth was confirmed from the court verdict on 30 December which mentioned that there were three genetically edited babies. The baby was later revealed in 2022 as Amy.
In February 2022, Chinese scientists called for building a special facility to care for and study the three children born with genetically edited genomes or 'CRISPR Babies'. They assert that errors could have occurred in the gene editing process. The scientists believe the children's genomes should be regularly sequenced and tested for 'abnormalities'. The proposal has received pushback from the international medical community citing invasion of the children's privacy and future abuses of power.
Gene therapy for rare diseases
On 10 November 2022, He announced that he was setting up a new laboratory in Beijing for research on gene therapy for rare genetic diseases, saying on Twitter: "Today, I moved in my new office in Beijing. This is the first day for Jiankui He Lab." On 24 November, he wrote: "Gene therapy in Western countries often costs millions of dollars, which makes many families fall into poverty due to illness. With the support of social philanthropists, we will overcome three to five genetic diseases within two to three years to benefit families with rare diseases." His first plan is to make a gene therapy for Duchenne muscular dystrophy that causes gradual muscle degeneration particularly in boys. He also said on a microblogging site, Weibo, that he had applied for government funding for a DNA synthesiser project, commenting: "[I will] continue the scientific research and serve the country... The biggest use of the DNA synthesiser I plan to make is for information storage. A fingernail-sized piece of synthetic DNA can store the contents of books from the entire national library."
Human gene-editing controversy
Revelation
He Jiankui's human gene-editing clinical experiment was conducted without public discussion in the scientific community. It was first made public on 25 November 2018 when Antonio Regalado published a story about the work in MIT Technology Review, based on documents that had been posted earlier that month on the Chinese clinical trials registry. He Jiankui refused to comment on whether the pregnancies were aborted or carried on. It was only after the story was posted that the experiment was revealed in a promotional video on YouTube by He Jiankui and the next day in the Associated Press report. He Jiankui had engaged a public relations firm as well.
Reaction
He Jiankui's conduct was widely condemned. On 26 November, 122 Chinese scientists issued a joint statement that He's works were unethical, crazy, insane, and "a huge blow to the global reputation and development of Chinese science". Other Chinese scientists and institutions harshly criticized He; an article in Nature stated that concerns about He's conduct were "particularly acute in China, where scientists are sensitive to the country's reputation as the Wild West of biomedical research". An eminent bioethicist, Ren-zong Qiu, speaking at the Second International Summit on Human Genome Editing, commented on He's research as "a practice with the least degree of ethical justifiability and acceptability". Geneticist Eric Topol stated, "This is far too premature ... We're dealing with the operating instructions of a human being. It's a big deal." Nobel Prize-winning biologist David Baltimore considered the work "irresponsible". Developmental biologist Kathy Niakan of the Francis Crick Institute said, "If true...this would be a highly irresponsible, unethical and dangerous use of genome editing technology." Medical ethicist Julian Savulescu of the University of Oxford noted, "If true, this experiment is monstrous." Bioethicist Henry T. Greely of Stanford Law School declared, "I unequivocally condemn the experiment," and later, "He Jiankui’s experiment was, amazingly, even worse than I first thought." Nobel prize-winning biochemist Jennifer Doudna, of the University of California, Berkeley, a pioneer of the CRISPR/Cas9 technology, condemned the research. The National Institutes of Health (NIH) of United States announced a statement on 28 November 2018 signed by its Director Francis S. Collins, condemning He and his team for intentionally flouting international ethical norms by doing such irresponsible work, and criticizing that He's "project was largely carried out in secret, the medical necessity for inactivation of CCR5 in these infants is utterly unconvincing, the informed consent process appears highly questionable, and the possibility of damaging off-target effects has not been satisfactorily explored". NIH claims no support for the use of gene-editing technologies in human embryos. The Chinese Academy of Medical Sciences published an announcement in the journal Lancet, stating that they "are opposed to any clinical operation of human embryo genome editing for reproductive purposes in violation of laws, regulations, and ethical norms in the absence of full scientific evaluation", and condemning He for violating relevant ethical regulations and guidelines that have been clearly documented by the Chinese government. They emphasized that the "genome editing of germ cells or early embryos is still in the stage of basic research, ... scientific research institutions and researchers should not undertake clinical operations of genome editing of human germ cells for reproductive purposes, nor should they fund such research", and they will "develop and issue further operational technical and ethical guidelines as soon as possible to guide and standardise relevant research and applications according to the highest scientific and ethical standards." In April 2019, genetics experts from the Chinese Academy of Science (CAS) noted, “[We] believe there is no sound scientific reason to perform this type of gene editing on the human germline, and that the behavior of He [Jiankui] and his team represents a gross violation of both the Chinese regulations and the consensus reached by the international science community. We strongly condemn their actions as extremely irresponsible, both scientifically and ethically.”
Others were less critical of He's experiment. George Church, a geneticist at Harvard University, defended some aspects of the experiment and said gene editing for HIV resistance was "justifiable" since HIV is "a major and growing public health threat", but questioned the decision of this project to allow one of the embryos to be used in a pregnancy attempt, since the use of that embryo suggests that the researchers’ "main emphasis was on testing editing rather than avoiding this disease". Arthur Caplan, bioethicist at the New York University School of Medicine, said that engineering human genes is inevitable and, although there are concerns of creating "designer babies", medical researchers are more interested in using the technology to prevent and treat diseases, much like the type of experiments performed by He. Carl Zimmer compared the reaction to He's human gene editing experiment to the initial reactions and subsequent debate over mitochondrial replacement therapy (MRT), and the eventual regulatory approval of MRT in the United Kingdom.
Investigation
The Southern University of Science and Technology stated that He Jiankui had been on unpaid leave since February 2018, and his research was conducted outside of their campus; the university and his department said they were unaware of the research project and said it was inviting international experts to form an independent committee to investigate the incident, and would release the results to the public. Local authorities and the Chinese government also opened investigations.
As of news reported on 28 December 2018, He was sequestered in a university apartment and under guard. According to news reported on 7 January 2019, he could face severe consequences. William Hurlbut, Stanford University neuroscientist and bioethicist, reported that he was in contact with He who was staying in a university apartment in Shenzhen “by mutual agreement” and was free to leave; often visiting the gym and taking walks with his wife. Nonetheless, He may have been under some form of surveillance.
On 25 February 2019, some suggested the Chinese government may have helped fund the CRISPR babies experiment, at least in part. Later reports showed that the fund for He's project was raised by himself to evade regulation, and no Chinese government funds were involved.
Preliminary authoritative report
An investigating task force set up by the Guangdong Provincial Health Commission released a preliminary report on January 21, 2019, stated that He Jiankui had defied government bans and conducted the research in the pursuit of personal fame and gain. The report confirmed that He had recruited eight couples to participate in his experiment, resulting in two pregnancies, one of which gave birth to the gene-edited twin girls in November 2018. The babies are now under medical supervision. The report further said He had made forged ethical review papers in order to enlist volunteers for the procedure, and had raised his own funds deliberately evading oversight, and organized a team that included some overseas members to carry out the illegal project. Officials from the investigation said that He, as well as other relevant personnel and organizations, will receive punishment per relevant laws and regulations, and those who are suspected of committing crimes will be charged.
Aftermath
The SUSTech announced a statement on its website on 21 January 2019 that He Jiankui had been fired.
On 30 December 2019, the Shenzhen City Nanshan District People's Court sentenced He Jiankui to three years in prison and fined him 3 million RMB (about US$). His collaborators received less penalty – Zhang Renli of the Guangdong Academy of Medical Sciences and Guangdong General Hospital, a two-year prison sentence and a 1-million RMB (about US$) fine, and Qin Jinzhou of the Southern University of Science and Technology, an 18-month prison sentence and a 500,000 RMB (about US$) fine. The three were found guilty of having "forged ethical review documents and misled doctors into unknowingly implanting gene-edited embryos into two women."
In May 2019, lawyers in China reported, in light of the purported creation by He Jiankui of the first gene-edited humans, the drafting of regulations that anyone manipulating the human genome by gene-editing techniques would be held responsible for any related adverse consequences. In December 2019, MIT Technology Review reported an overview of the controversy to date, including excerpts of the unpublished research manuscript.
In February 2019, scientists reported that the gene modification made in Lulu and Nana likely also confers cognitive benefits. While health journalist Julia Belluz has speculated in Vox that this may have been a motivation for He Jiankui to work on modifying this gene,) Antonio Regalado of MIT Technology Review found no evidence that He Jiankui had interest in this area.
In 2019, the World Health Organization (WHO) has launched a global registry to track research on human genome editing, after a call to halt all work on genome editing.
After the incident
On 21 February 2023, Hong Kong newspaper Ming Pao reported that He Jiankui said his application for a Hong Kong entry permit through the Top Talent Pass Scheme had been approved. Late that night, the Government of Hong Kong made a public announcement, suggesting that after inspecting the relevant applications, the Immigration Department suspected that He Jiankui had obtained a Hong Kong entry permit by making false statements. The Director of Immigration had declared He Jiankui's entry permit invalid, and a criminal investigation would be conducted.
On 8 September 2023, Wuchang Technical College (武昌理工学院), a private undergraduate college in Wuhan, Hubei, established the Institute of Genetic Medicine, with He Jiankui serving as the inaugural director.
In popular culture
He Jiankui's life and his CRISPR experiment were presented in the documentary Make People Better, released in 2022. The film described, "A Chinese scientist disappears after developing the first designer babies, shocking the world and the entire scientific community, but an investigation shows he may not have been alone in his experiment to create "better" human beings." Directed by Cody Sheehy, the expert panel included Antonio Regalado and Benjamin Hurlbut of the Arizona State University. The documentary originated from a Rhumbline Media project on genetic engineering titled Code of the Wild: The Nature of Us started in 2018 by Sheehy and Samira Kiani, a biotechnologist at Arizona State University.
His account is depicted in The CRISPR Generation: The Story of the World’s First Gene-Edited Babies, a 2019 book by Kiran Musunuru, a cardiologist at the University of Pennsylvania.
His story is narrated in the 2020 book The Mutant Project: Inside the Global Race to Genetically Modify Humans, written by Eben Kirksey, an anthropologist at the University of Oxford.
A documentary book CRISPR People: The Science and Ethics of Editing Humans, written by Henry Greely, was published in 2021.
See also
Assisted reproduction technology
Human Nature (2019 CRISPR film documentary)
Unnatural Selection (2019 TV documentary)
References
External links
(Archived) at SUSTech
Faculty profile (Archived) at SUSTech
1984 births
Living people
Biomedical engineers
Chinese geneticists
People from Loudi
Biologists from Hunan
University of Science and Technology of China alumni
Rice University alumni
Stanford University staff
Academic staff of the Southern University of Science and Technology
Genome editing
Chinese bioengineers
Educators from Hunan
Chinese prisoners and detainees
People involved in scientific misconduct incidents
Prisoners and detainees of China
Chinese eugenicists | He Jiankui | [
"Engineering",
"Biology"
] | 4,559 | [
"Genetics techniques",
"Genetic engineering",
"Genome editing"
] |
59,179,595 | https://en.wikipedia.org/wiki/T.%20S.%20R.%20Prasada%20Rao | Turaga Sundara Rama Prasada Rao (20 January 1939 – 7 April 2022) was an Indian engineer, known for his contributions in the fields of petroleum refining and heterogeneous catalysis. He was a former director of the Indian Institute of Petroleum and a former deputy general manager of the Indian Petrochemicals Corporation Limited. He was known for his studies in petrochemical engineering; his studies have been documented by way of a number of articles and Google Scholar, an online repository of scientific articles has listed 123 of them. He also co-edited a book, Recent Advances in Basic and Applied Aspects of Industrial Catalysis, published by Elsevier.
Born on 20 January 1939, Rao was an elected fellow of Indian National Academy of Engineering, and the Indian Academy of Sciences. He was also a member of Andhra Pradesh Akademi of Sciences, Indian Institute of Chemical Engineers, and New York Academy of Sciences. He shared the 1996 Om Prakash Bhasin Award for Engineering with M. R. Srinivasan and C. G. Krishnadas Nair. He received the Petrotech Lifetime Achievement Award in 2004. He was also a recipient of several other honors including Chemtech Outstanding Scientist Award, K. G. Naik Gold Medal, FICCI Award Technology Award of the Council of Scientific and Industrial Research.
Rao died in Hyderabad on 7 April 2022, at the age of 83.
Selected bibliography
Books
Articles
Notes
References
External links
1939 births
2022 deaths
Indian engineers
Petroleum engineers
Fellows of the Indian Academy of Sciences
Fellows of the Indian National Academy of Engineering
People from Machilipatnam | T. S. R. Prasada Rao | [
"Engineering"
] | 327 | [
"Petroleum engineers",
"Petroleum engineering"
] |
59,180,227 | https://en.wikipedia.org/wiki/Uncinocarpus%20queenslandicus | Uncinocarpus queenslandicus is a species of microfungi that grows in soil and keratinous materials, such as hair. It was the fourth species to be designated as part of the genus Uncinocarpus. Its name is derived from the Australian state of Queensland, where it was first isolated.
Taxonomy
Three synonyms for U. queenslandicus were first described in 1976 by A.E. Apinis and R.G. Rees as Apinisa queenslandicus during a survey of keratinous soil fungi in Queensland, Australia. Indian mycologists Banani Sur and Gouri R. Ghosh first described Orromyces spiralis in 1985 during a survey of keratinophilic soil fungi. In 1987, Spanish mycologists J. Guarro, L. Punsola and J. Cano first described Byssonygena reticulata as the type species of a new genus.
Canadian mycologists Lynne Sigler, Arlene Flis and J.W. Carmichael first proposed that all three of these species be placed in the genus Uncinocarpus in 1998. Though crossings between these three species and U. queenslandicus were either unsuccessful, or not performed in the case of O. spiralis they based their decision on each of the species' morphological similarities to U. orissi, as well as their ability to degrade keratin, a characteristic feature of Uncinocarpus.
Description
In culture on potato yeast extract, colonies of U. queenslandicus are yellowish white in colour before darkening to a tan or light brown. Colonies take on a velvety to cottony texture. It produces the enzyme urease, allowing it to convert urea to ammonia and carbon dioxide. U. queenslandicus possesses appendages that are loosely or irregularly spiraled.
References
Onygenales
Fungi described in 1998
Fungus species | Uncinocarpus queenslandicus | [
"Biology"
] | 384 | [
"Fungi",
"Fungus species"
] |
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