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78,686,414 | https://en.wikipedia.org/wiki/NGC%201164 | NGC 1164 is a barred spiral galaxy located in the constellation Eridanus, approximately 60 million light-years from Earth. It was discovered by the astronomer John Herschel in 1834. NGC 1164 is classified as a (R')SAB(rs)b type spiral galaxy, with a prominent central bar structure and well-defined spiral arms.
Structure and features
NGC 1164 is a relatively large galaxy, measuring roughly 100,000 light-years in diameter. It is characterized by its bright, central bulge and the elongated bar structure that spans its core. The galaxy's spiral arms are well-developed and feature areas of intense star formation.
Observations of NGC 1164 using both optical and infrared telescopes have revealed a rich population of stars and gas clouds, indicating an active star-forming region within the galaxy. It also displays signs of a central supermassive black hole, a common feature in many large galaxies.
Location and distance
NGC 1164 is located in the southern constellation Eridanus, which is visible from Earth's southern hemisphere. It lies at a distance of approximately 60 million light-years from the Milky Way, making it part of the larger structure of galaxies in the local universe.
Observational history
John Herschel discovered NGC 1164 in 1834 while observing the southern skies. Since its discovery, it has been a subject of interest for both amateur and professional astronomers, especially due to its relatively well-preserved spiral structure and central bar.
It has been studied in various wavelengths of light, including optical, infrared, and radio, contributing valuable insights into the mechanisms of star formation and galactic dynamics. Modern observations, including those by the Hubble Space Telescope, have helped to create detailed images of the galaxy.
Significance in astronomy
NGC 1164 is part of the catalog of galaxies known as the New General Catalogue (NGC), a collection of astronomical objects compiled in the 19th century. As a barred spiral galaxy, NGC 1164 is an important example of this type of galaxy, allowing astronomers to study the structure, dynamics, and evolution of barred spirals in greater detail.
Research on galaxies like NGC 1164 helps to improve our understanding of galactic formation, the role of central black holes, and the processes that drive star formation in different regions of the universe.
Supernovae
Two supernovae have been observed in NGC 1164:
SN1993ab (typeIa, mag. 18) was discovered by Jean Mueller on 24 September 1993.
SN2016hsr (typeII, mag. 18.5) was discovered by the Lick Observatory Supernova Search (LOSS) on 2 November 2016.
See also
List of NGC objects
List of galaxies
Barred spiral galaxy
John Herschel
References
External links
NASA/IPAC Extragalactic Database (NED) - NGC 1164
SIMBAD Astronomical Database - NGC 1164
Hubble Space Telescope - NGC 1164 (Image and Information)
NGC objects
Astronomical objects discovered in 1834
Discoveries by John Herschel | NGC 1164 | [
"Astronomy"
] | 594 | [
"Eridanus (constellation)",
"Constellations"
] |
78,688,465 | https://en.wikipedia.org/wiki/C/2024%20E1%20%28Wierzcho%C5%9B%29 | C/2024 E1 (Wierzchoś) is a hyperbolic Oort cloud comet, discovered on 3 March 2024 by Polish astronomer Kacper Wierzchoś. It will reach perihelion on 20 January 2026, when it could reach an apparent magnitude of +5.
Discovery
During a routine Mt. Lemmon survey (G96) search on 3 March 2024, one of the scientists participating in the project, Kacper Wierzchoś, spotted a moving object in four, 30-second exposure images taken using an f/1.6 Cassegrain telescope, equipped with a 111.5 megapixel (10,560 x 10,560 pixel) CCD. It appeared as a 20th-magnitude object in the constellation Draco, about 2 degrees north of the star ν Dra. Since the discovery announcement, the Zwicky Transient Facility have reported that they obtained precovery images of the comet between 15 and 29 February 2024. The comet was reported to have a condensed coma about 4 arcseconds in diameter and a tail about 6 arcseconds long.
Perihelion
The comet will approach perihelion on 20 January 2026 around 18 UT. It will appear about 21 degrees from the Sun and will be visible from the Southern Hemisphere. Peak brightness will reach approximately +5 magnitude, meaning it could be visible through binoculars. It will be about from Earth.
References
External links
Non-periodic comets
Hyperbolic comets
Near-Earth comets
Comets in 2024
Oort cloud | C/2024 E1 (Wierzchoś) | [
"Astronomy"
] | 321 | [
"Astronomical hypotheses",
"Oort cloud"
] |
78,689,128 | https://en.wikipedia.org/wiki/Broad%20Arrow%20Policy | The Broad Arrow Policy was a policy of the British government from 1691 to preserve tall trees in the American colonies which were of critical use for the Royal Navy. It applied to Massachusetts from 1691. It was extended to New Hampshire (1698); New England, New York, and New Jersey (1711); and Nova Scotia (1721). The colonists disliked the policy and it was one of the grievances that led to the American Revolution.
The broad arrow symbol was used by the British to mark trees (especially the eastern white pine) intended for ship building use. Three axe strikes, resembling an arrowhead and shaft, were marked on large mast-grade trees. Use of the broad arrow mark commenced in earnest in 1691 with the Massachusetts Charter, which contained a Mast Preservation Clause specifying:
Initially England imported its mast trees from the Baltic states, but it was an expensive, lengthy and politically treacherous proposition. Much of British naval policy at the time revolved around keeping the trade route to the Baltics open. With Baltic timber becoming less appealing to use, the Admiralty's eye turned towards the Colonies. Colonists paid little attention to the Charter's Mast Preservation Clause, and tree harvesting increased with disregard for broad arrow protected trees. However, as Baltic imports decreased, the British timber trade increasingly depended on North American trees, and enforcement of broad arrow policies increased. Persons appointed to the position of Surveyor-General of His Majesty's Woods were responsible for selecting, marking and recording trees as well as policing and enforcing the unlicensed cutting of protected trees. This process was open to abuse, and the British monopoly was very unpopular with colonists. Part of the reason was that many protected trees were on either town-owned or privately owned lands.
Colonists could only sell mast trees to the British, but were substantially underpaid for the lumber. Even though it was illegal for the colonists to sell to enemies of the crown, both the French and the Spanish were in the market for mast trees as well and would pay a much better price. Acts of Parliament in 1711, 1722 and the 1772 Timber for the Navy Act extended protection finally to trees and resulted in the Pine Tree Riot that same year. This was one of the first acts of rebellion by the American colonists leading to the American Revolution in 1775, and a flag bearing a white pine was flown at the Battle of Bunker Hill.
See also
Forest conservation in the United States
Notes
Further reading
Conway, Dick. "Roots of Revolution" American History (Dec 2002) 37#4 pp. 56–59.
Kinney, Jay P., Forest legislation in America prior to March 4, 1789 (1916) online
Malone, Joseph J. Pine Trees and Politics: The Naval Stores and Forest Policy in Colonial New England, 1691-1775 (U of Washington Press, 1985) online review of this book
Marshall, Philip. "The Historical and Physiological Ecology of Eastern White Pine (Pinus strobus L.) in Northeast Connecticut, 1700-2000" (PhD dissertation, Yale University; ProQuest Dissertations & Theses, 2011. 34969700).
Roberts, Strother E. "Pines, profits, and popular politics: Responses to the White Pine Acts in the colonial Connecticut River Valley" New England Quarterly, (2010) 83(1), 73–101. https://doi.org/10.1162/tneq.2010.83.1.73
"The King's Broad Arrow and Eastern White Pine," NELMA (2020) online
Shipbuilding
Royal Navy
Forestry in the United States
Forest conservation | Broad Arrow Policy | [
"Engineering"
] | 730 | [
"Shipbuilding",
"Marine engineering"
] |
78,689,524 | https://en.wikipedia.org/wiki/Dulcibella | Dulcibella camanchaca is a species of amphipod crustacean discovered in the Atacama Trench, at depths of nearly in the South Pacific Ocean near Chile. Measuring approximately in length, this predatory amphipod is adapted to the extreme conditions of the hadal zone, making it one of the deepest-living predators identified to date.
Taxonomy
Dulcibella camanchaca belongs to the family Eusiridae and was formally described in 2024 by marine biologists Johanna Weston and Carolina Gonzále. The genus name, Dulcibella, is derived from Dulcinea, a character in Don Quixote, consistent with a tradition of naming amphipods after literary figures. The species epithet, camanchaca, originates from an Andean word meaning "darkness," referencing its deep-sea habitat.
Discovery
The species was discovered during a 2023 oceanographic expedition that investigated the biodiversity of the Atacama Trench. The research team used advanced deep-sea exploration equipment to collect specimens from depths nearing 8,000 meters. The identification of D. camanchaca as a new species was confirmed through DNA analysis and detailed morphological examination.
This discovery has contributed to the growing recognition of the Atacama Trench as a region of high biodiversity and endemism.
Morphology and behavior
Dulcibella camanchaca is larger than most amphipods found at similar depths. It exhibits predatory behavior, using specialized appendages to capture and consume smaller crustaceans. These adaptations suggest an ecological role as an active predator in the hadal zone.
Significance
The identification of D. camanchaca highlights the ecological importance of the Atacama Trench and the potential for further discoveries in deep-sea environments. Continued exploration of these regions may yield insights into the adaptations and biodiversity of organisms living in extreme conditions.
References
Amphipoda
Animals described in 2024
Monotypic amphipod genera
Fauna of the Pacific Ocean
Endemic fauna of Chile
Species described in the 21st century | Dulcibella | [
"Biology"
] | 407 | [
"Species described in the 21st century",
"Species by year of formal description"
] |
78,690,934 | https://en.wikipedia.org/wiki/Tiffany%20Santos | Tiffany Suzanne Santos (born 1980) is an American electrical engineer and materials scientist who works for the research division of Western Digital as an expert on tunnel magnetoresistance, non-volatile memory, and magnetic thin-film memory, and as Director of Non-Volatile Memory Materials Research.
Education and career
Santos is the daughter of Ted Santos, a physician and pathologist in Valdosta, Georgia. After graduating as salutatorian from Valdosta High School, she became a student of materials science and engineering at the Massachusetts Institute of Technology, where she received a bachelor's degree in 2002 and a Ph.D. in 2007 under the supervision of Jagadeesh Moodera. She received the Outstanding Senior Thesis award of the MIT Department of Materials Science and Engineering for her bachelor's thesis, Ferromagnetic Europium Oxide as a Spin-Filter Material. Her doctoral dissertation, Europium oxide as a perfect electron spin filter, was based on research applying magnetic materials in spintronics.
She became a postdoctoral researcher and then staff scientist at the Argonne National Laboratory before joining Hitachi Global Storage Technologies (HGST) in 2011. HGST was acquired by Western Digital in 2012.
Recognition
Santos received the L’Oréal USA Fellowship for Women in Science in 2009. In 2022 she was a distinguished lecturer of the IEEE Magnetics Society.
She was named as a Fellow of the American Physical Society (APS) in 2024, after a nomination from the APS Topical Group on Magnetism and Its Applications, "for innovative contributions in synthesis and characterization of novel ultrathin magnetic films and interfaces, and tailoring their properties for optimal performance, especially in magnetic data storage and spin-transport devices".
References
External links
1980 births
Living people
People from Valdosta, Georgia
American electrical engineers
American women engineers
Women electrical engineers
American materials scientists
Women materials scientists and engineers
Massachusetts Institute of Technology alumni
Argonne National Laboratory people
Western Digital people
Fellows of the American Physical Society | Tiffany Santos | [
"Materials_science",
"Technology"
] | 406 | [
"Women materials scientists and engineers",
"Materials scientists and engineers",
"Women in science and technology"
] |
78,691,646 | https://en.wikipedia.org/wiki/NGC%204129 | NGC4129 is a barred spiral galaxy in the constellation of Virgo. Its velocity with respect to the cosmic microwave background for is , which corresponds to a Hubble distance of . Additionally, 12 non-redshift measurements give a distance of . It was discovered by German-British astronomer William Herschel on 3 March 1786. It was also observed by Heinrich d'Arrest on 15 March 1866, causing it to be listed twice in the New General Catalogue, as NGC 4129 and as NGC 4130.
Supernovae
Two supernovae have been observed in NGC 4129:
SN1954aa (type unknown, mag. 19.9) was discovered by Fritz Zwicky on 2 April 1954.
SN2002E (typeII, mag. 19.9) was discovered by LOTOSS (Lick Observatory and Tenagra Observatory Supernova Searches) on 16 January 2002.
See also
List of NGC objects (4001–5000)
References
External links
4129
038580
-01-31-006
12063-0845
Virgo (constellation)
17860303
Discoveries by William Herschel
Barred spiral galaxies | NGC 4129 | [
"Astronomy"
] | 233 | [
"Virgo (constellation)",
"Constellations"
] |
78,691,910 | https://en.wikipedia.org/wiki/Heinz%20Gumin%20Prize | The Heinz Gumin Prize for Mathematics is awarded every three to four years to an outstanding mathematician in Germany, Austria or Switzerland. The prize is given by the Carl Friedrich von Siemens Foundation, and is named after the mathematician and computer scientist Heinz Gumin (1928–2008), who was chairman of the Board of that foundation for more than 20 years. At 50,000 euros, the Gumin Prize is the most highly endowed mathematics prize in Germany.
Award Winners
2010 Gerd Faltings, Director at the Max Planck Institute for Mathematics, Bonn. For his groundbreaking methods and results in arithmetic geometry, which have had a lasting impact on the areas of number theory and geometry.
2013 Stefan Müller, Professor of Mathematics at the University of Bonn and at the Hausdorff Center for Mathematics, Bonn. For his groundbreaking contributions to the calculus of variations and elliptic regularity theory, often motivated by innovative applications in solid mechanics
2016 Wendelin Werner, Professor of Mathematics at the Swiss Federal Institute of Technology in Zurich. For his groundbreaking contributions to the mathematical justification of universal properties of Brownian motion with applications to central assumptions in statistical physics.
2020 Wolfgang Hackbusch, former director of the Max Planck Institute for Mathematics in the Sciences, Leipzig. For groundbreaking contributions to numerical mathematics, in particular to the development of H-matrices and hierarchical tensors.
2024 Don Zagier, former director of the Max Planck Institute for Mathematics, Bonn. For groundbreaking research work on number theory and the theory of modular forms.
References
Mathematics awards | Heinz Gumin Prize | [
"Technology"
] | 305 | [
"Science and technology awards",
"Mathematics awards"
] |
78,692,457 | https://en.wikipedia.org/wiki/NGC%204782 | NGC4782 is an elliptical galaxy in the constellation of Corvus. Its velocity with respect to the cosmic microwave background for is , which corresponds to a Hubble distance of . However, nine non-redshift measurements give a closer distance of . It was discovered by German-British astronomer William Herschel on 27 March 1786.
NGC 4782 along with NGC 4783 are listed together as Holm485 in Erik Holmberg's A Study of Double and Multiple Galaxies Together with Inquiries into some General Metagalactic Problems, published in 1937. They are also listed as VV201 in the Vorontsov-Vel'yaminov Interacting Galaxies catalogue. However, since NGC 4782 is about farther away than NGC 4783 (using Hubble distance), the grouping is purely optical.
The SIMBAD database lists NGC4782 as a radio galaxy, i.e. it has giant regions of radio emission extending well beyond its visible structure.
Supernovae
Two supernovae have been observed in NGC 4782:
SN1956B (type unknown, mag. 18.6) was discovered by Fritz Zwicky on 8 April 1956.
SN2015B (typeIa, mag. 15) was discovered by the Italian Supernovae Search Project on 5 January 2015.
See also
List of NGC objects (4001–5000)
References
External links
4782
043924
-02-33-050
Corvus (constellation)
17860327
Discoveries by William Herschel
Elliptical galaxies
Radio galaxies | NGC 4782 | [
"Astronomy"
] | 319 | [
"Corvus (constellation)",
"Constellations"
] |
78,692,919 | https://en.wikipedia.org/wiki/EquipmentShare | EquipmentShare is an American company specializing in construction equipment rental, sales, and technology services. It was founded in 2015 and is based in Columbia, Missouri. In 2024 there were 215 locations in 38 U.S. States. The company has seen rapid growth, with 60 locations opening in 2024. According to Bloomberg News the company is considering an public offering as soon as 2025.
References
External links
equipmentshare.com
Technology companies of the United States
Construction and civil engineering companies
American companies established in 2015
Companies based in Columbia, Missouri
2015 establishments in Missouri | EquipmentShare | [
"Engineering"
] | 115 | [
"Construction and civil engineering companies",
"Civil engineering organizations"
] |
78,693,668 | https://en.wikipedia.org/wiki/Double-bay%20system | In architecture, the double bay system (or engaged system) is the arrangement commonly found in Romanesque architecture, where the internal space of basilicas is subdivided into three spaces, the nave and two side aisles, with aisles having half the width of the nave. This arrangement required the ribbed vaults in the aisles to be twice smaller as well, so supports in the side aisles had to be spaced at half the step of the supports in the nave.
Double-bay systems in Romanesque churches are almost always reflected in the alternation of supports, usually between compound piers and round columns, although some researchers see to purely decorative alternation in some buildings, like the Ely Cathedral.
References
Sources
Further reading
Arches and vaults | Double-bay system | [
"Engineering"
] | 142 | [
"Architecture stubs",
"Architecture"
] |
78,693,846 | https://en.wikipedia.org/wiki/Benjamin%20Gung | Benjamin W. Gung (born July 15, 1953) is a Chinese American organic chemist and academic. He is an emeritus Professor of Chemistry at Miami University.
Gung and his research group have concentrated on two main areas: organic synthesis, including the total synthesis of natural products and the development of new methodologies, and the study of nonbonding interactions involving aromatic rings. Together, they have synthesized a variety of natural products.
Gung is ranked among the top 2 percent of researchers worldwide, according to a recent Stanford University study that used citation analysis to identify leading scholars among nearly eight million authors.
Education and career
After receiving a bachelor's degree in chemistry from Nanjing University in China in 1982, Gung pursued graduate studies in organic chemistry at Kansas State University, where he completed his M.S. in 1984 and Ph.D. in 1987, studying under Richard McDonald and Duy Hua. Following a two-year postdoctoral appointment at the University of South Carolina under James Marshall, he joined the faculty at Miami University, in Oxford, Ohio in 1989. He was promoted to associate professor in 1994 and Full Professor in 2003, and during his tenure there, he spent his sabbatical leave doing research in the group of William Roush at the University of Michigan in 1999. Since 2024, he has been serving as an emeritus Professor.
Gung has supervised graduate and undergraduate students in chemistry research. He has held key roles, including serving as a reviewer for five NSF-Career Applications in 2004 and organizing an NSF-sponsored REU program at Miami University from 2004 to 2006. He also reviewed NIH Fellowship Study Sections from 2006 to 2011 and was a Co-PI on an NSF-DUE project from 2011 to 2014. After retiring in 2024, he continues collaborating with undergraduate students on research, with his publication, co-authored with Miami University students, focusing on amino acids and peptides as effective ligands for metal-centered catalysts
Research
Gung has made contributions to the field of organic chemistry, with over 100 published journal articles. His research interests include stereochemistry in organic reactions, non-covalent molecular interactions, methods development, and computational chemistry. He is known for his studies in stereochemical mechanism and in the development of a Transannular [4+3] cycloaddition reaction with gold-stabilized allylic carbocations as reactive intermediate.
Selected articles
Gung, B. W. (1996). Diastereofacial selection in nucleophilic additions to unsymmetrically substituted trigonal carbons. Tetrahedron, 52(15), 5263–5301.
Gung, B. W. (1999). Structure distortions in heteroatom-substituted cyclohexanones, adamantanones, and adamantanes: Origin of diastereofacial selectivity. Chemical reviews, 99(5), 1377–1386.
Gung, B. W., Xue, X., & Reich, H. J. (2005). The strength of parallel-displaced arene− arene interactions in chloroform. The Journal of Organic Chemistry, 70(9), 3641–3644.
Gung, B. W., Patel, M., & Xue, X. (2005). A threshold for charge transfer in aromatic interactions? A quantitative study of π-stacking interactions. The Journal of Organic Chemistry, 70(25), 10532–10537.
Gung, B. W., & Amicangelo, J. C. (2006). Substituent Effects in C6F6 C6H5X Stacking Interactions. The Journal of organic chemistry, 71(25), 9261–9270.
Gung, B. W., Zou, Y., Xu, Z., Amicangelo, J. C., Irwin, D. G., Ma, S., & Zhou, H. C. (2008). Quantitative study of interactions between oxygen lone pair and aromatic rings: Substituent effect and the importance of closeness of contact. The Journal of Organic Chemistry, 73(2), 689–693.
References
Organic chemists
Nanjing University alumni
Kansas State University alumni
Miami University faculty
1953 births
Living people | Benjamin Gung | [
"Chemistry"
] | 890 | [
"Organic chemists"
] |
78,697,133 | https://en.wikipedia.org/wiki/NGC%201166 | NGC 1166 is a barred spiral galaxy located in the constellation Eridanus. It is situated approximately 53 million light-years away from Earth and was discovered by the British astronomer John Herschel on November 17, 1834.
Structure and characteristics
NGC 1166 is classified as an Sb-type barred spiral galaxy. This means the galaxy has a well-defined bar at its center, with spiral arms extending outward. It is a relatively medium-sized galaxy, spanning approximately 2.0 x 1.8 arcminutes in the sky. The galaxy exhibits active star formation in its spiral arms, where new stars are being created from interstellar gas and dust.
NGC 1166 also has a high surface brightness, making it an interesting target for both optical and infrared studies.
Discovery
NGC 1166 was discovered by the renowned astronomer John Herschel during his survey of the southern skies in 1834. Herschel's extensive cataloging of nebulae and galaxies led to the inclusion of NGC 1166 in the New General Catalogue (NGC), where it is listed among other deep-sky objects.
Location and distance
NGC 1166 is located in the constellation Eridanus, a large and prominent southern constellation. The galaxy is about 53 million light-years away from Earth, with a radial velocity of approximately 3530 km/s, indicating its motion relative to the Milky Way.
Importance and research
NGC 1166 is a useful object of study for astronomers researching the formation and evolution of barred spiral galaxies. Its relatively close proximity allows for detailed observation, and its active star-forming regions provide insights into the processes that drive galaxy evolution.
Supernovae
Two supernovae have been observed in NGC 1166:
SN2018htf (typeII, mag. 17.9) was discovered by the Puckett Observatory Supernovae Search (POSS) on 3 November 2018.
SN2021zby (typeIIb, mag. 18.162) was discovered by ATLAS on 17 September 2021.
See also
List of NGC objects
Barred spiral galaxy
John Herschel
References
External links
NASA/IPAC Extragalactic Database (NED) - NGC 1166
SIMBAD Astronomical Database - NGC 1166
Spiral galaxies
NGC objects
Eridanus (constellation) | NGC 1166 | [
"Astronomy"
] | 449 | [
"Eridanus (constellation)",
"Constellations"
] |
78,697,487 | https://en.wikipedia.org/wiki/NGC%207177 | NGC7177 is a barred spiral galaxy in the constellation of Pegasus. Its velocity with respect to the cosmic microwave background is , which corresponds to a Hubble distance of . However, 12 non-redshift measurements give a much farther distance of . It was discovered by German-British astronomer William Herschel on 15 October 1784.
The SIMBAD database lists NGC7177 as a LINER galaxy, i.e. a galaxy whose nucleus has an emission spectrum characterized by broad lines of weakly ionized atoms.
Supernovae
Two supernovae have been observed in NGC 7177:
SN1960L (type unknown, mag. 16) was discovered by Milton Humason on 14 August 1960.
SN1976E (type unknown, mag. 16.5) was discovered by Justus R. Dunlap of the Corralitos Observatory at Northwestern University on 23 September 1976.
See also
List of NGC objects (7001–7840)
References
External links
7177
11872
067823
+03-56-003
Pegasus (constellation)
17841015
Discoveries by William Herschel
Barred spiral galaxies
LINER galaxies | NGC 7177 | [
"Astronomy"
] | 237 | [
"Pegasus (constellation)",
"Constellations"
] |
78,698,617 | https://en.wikipedia.org/wiki/NGC%204727 | NGC4727 is a large barred spiral galaxy in the constellation of Corvus. Its velocity with respect to the cosmic microwave background for is , which corresponds to a Hubble distance of . It was discovered by German-British astronomer William Herschel on 8 February 1785. It was also observed by Lewis Swift on 27 April 1887, causing it to be listed twice in the New General Catalogue, as NGC 4727 and as NGC 4740.
NGC 4727 and NGC 4724 are listed together as Holm 470 in Erik Holmberg's A Study of Double and Multiple Galaxies Together with Inquiries into some General Metagalactic Problems, published in 1937.
Supernovae
Two supernovae have been observed in NGC 4727:
SN1965B (type unknown, mag. 16) was discovered by Enrique Chavira on 8 January 1965.
SN2003eg (typeII, mag. 15.8) was discovered by LOTOSS (Lick Observatory and Tenagra Observatory Supernova Searches) on 17 May 2003.
See also
List of NGC objects (4001–5000)
References
External links
4727
12483-1403
043499
-02-33-023
Corvus (constellation)
17850208
Discoveries by William Herschel
Barred spiral galaxies | NGC 4727 | [
"Astronomy"
] | 259 | [
"Corvus (constellation)",
"Constellations"
] |
78,699,108 | https://en.wikipedia.org/wiki/Karl%20F.%20Lindman | Karl Ferdinand Lindman (7 June 1874 – 14 February 1952) was a Finnish physicist and educator. Best known for his work on chiral media, he has performed the experimental demonstration of optical rotation of microwaves in an artificial chiral medium in 1914. For the most of his career, he was a professor of physics at Åbo Akademi University.
Biography
Karl Ferdinand Lindman was born on 7 June 1874 in Ekenäs, Grand Duchy of Finland to Karl Gustav and Lovisa Lindman. His father was a farmer with clerical duties. Receiving a degree of physics in 1895, Lindman obtained his PhD degree from University of Helsinki in 1901. He briefly resided in Leipzig from 1899 to 1901; his thesis work was partially done in Leipzig University.
Following his doctoral stufies, Lindman served as a secondary school teacher and authored textbooks in physics, chemistry and astronomy in Swedish and Finnish. He was a lecturer at Svenska normallyceum i Helsingfors, where he introduced laboratory courses. In 1907, he took sabbatical in England and Scotland to study teaching methods. Becoming a faculty member at Åbo Akademi University in 1918, he was appointed as the chair in physics in 1921, and served as the vice rector from 1921 to 1929. He also served as the dean of the Faculty of Mathematics and Natural Sciences during his tenure. Despite retiring in 1942, he carried a full teaching load until 1945.
Lindman was married to Hilma Lovisa Tallqvist. He died on 14 February 1952 and was survived by his son, Sven Lindman, who was a professor of political science in Åbo Akademi. A conference in honor of Lindman was organized in 1991 at Abo Akademi by Finnish chapters of URSI and IEEE. Electromagnetic Waves in Chiral and Bi-isotropic Media, a 1994 monograph on chiral and bi-isotropic media by Ismo Lindell and his colleagues, is dedicated to his honour.
Research and contributions to chiral media
Lindman was mainly an experimental physicist and his research work focused on electromagnetics: he is best known for his work on chiral media. In 1914, he has demonstrated the optical rotation in an artificial chiral medium experimentally. He has constructed the artificial medium from left- and right-handed copper helices that are suspended in cotton; he has observed that this composite material rotates the linearly polarized microwave signal in a circular waveguide apparatus. He has also shown that same number of left- and right-handed helices does not cause any polarization rotation. His observations were first reported in the same year in the proceedings of Finnish Society of Sciences and Letters; these were subsequently published in 1920 and 1922 in the German-language journal Annalen der Physik. Even though this experiment came after the Jagadish Chandra Bose's 1898 study on optical rotation of microwaves, it has acted as a progenitor to artificial dielectrics and metamaterials. The experiment was repeated in 1950s with more advanced apparatus and was subsequently adapted to terahertz waves in 2009. Following his publications from 1914 to early 1920s, Lindman continued his experiments in chirality and proposed different configurations to induce optical activity.
Lindman was also active in other areas of electromagnetics. His doctoral studies in University of Leipzig focused on the resonances and standing waves in a dipole antenna. In addition to resonances of wire antennas, Lindman has studied millimeter and infrared wave propagation, diffraction grids, scattering and waveguides. In 1940s, he studied the wave propagation in circular waveguides and parallel plates: these studies coincided with the flurry of interest in microwave propagation of waveguides for radar applications, stemming from the World War II.
Even though he did not publish any original research regarding the theory of relativity, he was critical of it and expressed his criticisms in his textbooks.
Selected publications
References
1874 births
1952 deaths
20th-century Finnish physicists
Microwave engineers
University of Helsinki alumni
Academic staff of Åbo Akademi University
People from Raseborg
20th-century Finnish educators
20th-century Finnish non-fiction writers
Textbook writers
Finnish schoolteachers
Finnish writers in Swedish
Relativity critics
Finnish expatriates in Germany
Experimental physicists | Karl F. Lindman | [
"Physics"
] | 861 | [
"Relativity critics",
"Experimental physics",
"Experimental physicists",
"Theory of relativity"
] |
78,699,643 | https://en.wikipedia.org/wiki/Noviflumuron | Noviflumuron is an insecticide of the benzoylurea class. It is an insect growth regulator that prevents juvenile termites from developing into adults by disrupting the synthesis of chitin, the main component of an insect's exoskeleton.
Noviflumuron is primarily used in termite bait products such as Sentricon.
References
Insecticides
Organochlorides
Organofluorides
Ureas
2-Fluorophenyl compounds | Noviflumuron | [
"Chemistry"
] | 97 | [
"Organic compounds",
"Organic compound stubs",
"Organic chemistry stubs",
"Ureas"
] |
78,699,678 | https://en.wikipedia.org/wiki/NGC%202565 | NGC2565 is a barred spiral galaxy in the constellation of Cancer. Its velocity with respect to the cosmic microwave background for is , which corresponds to a Hubble distance of . Additionally, 34 non-redshift measurements give a distance of . It was discovered by German-British astronomer J. Gerhard Lohse (bio-fr) in 1886.
NGC 2565 is a galaxy whose nucleus shines brightly in the ultraviolet. It is listed in the Markarian catalogue as Mrk 386.
NGC 2565 is surrounded by a ring, and is a starburst galaxy, as indicated by its entry in the NASA/IPAC Extragalactic Database.
NGC 2545 Group
NGC 2565 is a member of the NGC 2545 group (also known as LGG 156). The other galaxies in the group are NGC 2545, UGC 4308, CGCG 119-44 and CGCG 119-56.
Supernovae
Two supernovae have been observed in NGC 2565:
SN1960M (type I, mag. 17) was discovered by Alercio Gomes on 26 October 1960.
SN1992I (typeII, mag. 18) was discovered by Christian Buil (bio-fr) on 29 February 1992.
See also
List of NGC objects (2001–3000)
References
External links
2565
08168+2211
023362
+04-20-026
Cancer (constellation)
Astronomical objects discovered in 1886
Barred spiral galaxies
04334
0386
Starburst galaxies | NGC 2565 | [
"Astronomy"
] | 315 | [
"Cancer (constellation)",
"Constellations"
] |
78,699,697 | https://en.wikipedia.org/wiki/Biatoropsis%20usnearum | Biatoropsis usnearum is a species of parasitic fungus that grows exclusively on lichen species of the genus Usnea, particularly U. subfloridana, U. barbata, and U. florida. First described in 1934 by Veli Räsänen, it has become a significant model organism in fungal evolution studies due to its specialised host relationships. The fungus belongs to the order Tremellales, though its precise family classification remains uncertain. It forms distinctive swellings or galls on its host lichens, ranging in colour from pale pink to dark reddish-brown, and notably suppresses the production of host defensive compounds like usnic acid. While initially misclassified due to its unusual characteristics, modern microscopic and genetic studies have revealed it to be part of a species complex, with at least three additional species now recognised. Found across Europe and North America, B. usnearum preferentially infects young, growing parts of its host lichens, particularly branch tips and small branches. The species has become particularly important in understanding how parasitic fungi adapt to new hosts, as it demonstrates evolution through switching between different host species rather than evolving alongside a single host species over time.
Taxonomy
Historical classification
The taxonomic history of Biatoropsis usnearum spans over two centuries of scientific observation. Johann Jacob Dillenius first documented what would later be recognised as B. usnearum in his 1742 work "Historia Muscorum" describing small fleshy nodules closely appressed to Usnea branches. Erik Acharius, known as the "Father of Lichenology", made several observations of these structures between 1795 and 1810, referring to them variously as (seed-producing parts) and later distinguishing between normal -shaped apothecia (which he termed "orbilla") and what we now know to be basidiomata (which he termed "cephalodia").
Throughout the 19th and early 20th centuries, various authors applied different terms to describe these structures. Gray and Knowles used "cephalodia" in 1821 and 1929 respectively, while Smith introduced "pseudo-cephalodia" in 1918, and Ludwig Schaerer proposed "patellulae" in 1850.
Modern classification
Räsänen formally described Biatoropsis usnearum in 1934, initially classifying it as an ascomycete based on what he interpreted as asci containing hyaline, spores measuring 10–16 by 4–6.5 μm. In 1939, he further specified that these supposed asci were 8-spored. However, these structures were later recognised to be young probasidia.
In 1949, Rolf Santesson was the first to challenge its classification as an ascomycete, though he incorrectly suggested the structures were galls caused by Abrothallus parmeliarum. The true nature of B. usnearum as a heterobasidiomycete was not confirmed until 1990, when detailed microscopic examination revealed a hymenium with auricularioid basidia and no ascomycetous structures.
Current systematic position
Molecular studies have revealed that B. usnearum represents a species complex containing several distinct species. While B. usnearum sensu stricto remains widespread, recent research has shown that many specimens historically identified as this species must now be considered doubtfully identified due to morphological intermediacy between known species or lack of clear distinguishing characteristics. Three additional species were formally described from this complex in 2016:
B. hafellneri – Distinguished by having two-celled basidia with cells that elongate laterally at maturity, and by growing on species of the Usnea fragilescens aggregate
B. minuta – Characterised by small (less than 1 mm) brown to black basidiomatal galls, growing on Usnea barbata and U. lapponica
B. protousneae – Confined to Protousnea dusenii
Research has shown that host switching, rather than cospeciation, has been the primary driver of diversification within this group, particularly in host-specialised lineages. Different host-specific species have been found to occur in sympatry, suggesting that speciation occurs through adaptive specialization rather than geographic isolation.
The genus Biatoropsis was initially tentatively placed in the order Platygloeales based on its transversely septate basidia, absence of clamp connections, and strong morphological similarity to the genus Mycogloea. The genus can be distinguished from related taxa by its non-deciduous basidia, which differs from Mycogloea, and by the absence of distinct probasidia, unlike Platygloea which has swollen cells under the septate portion of basidia.
Biatoropsis usnearum produces an anamorph that strongly resembles Hormomyces aurantiacus. The anamorph is characterised by its hyphomycetous growth form, producing long branching chains of hyaline, ellipsoid conidia measuring 3–5 by 2–3.5 μm.
While several species of Tremella possess transverse or oblique basidial septa similar to B. usnearum, its placement outside the Tremellales is supported by its distinctive basidial morphology and the absence of clamp connections. However, definitive placement within the Platygloeales awaits ultrastructural analysis of septal pores, as suggested by Moore's 1990 work on the order. The taxonomic understanding of this species was hampered for many years because lichenologists examining infected Usnea specimens generally had limited experience with heterobasidiomycetes, leading to misinterpretation of probasidial structures as asci or spores.
Description
Biatoropsis usnearum forms distinctive growths, known as basidiomata, on its host lichens. These structures show considerable variation in their appearance, but typically appear as rounded, convex swellings with a narrowed base. The basidiomata can range in colour from pale pink to reddish brown or black, and measure between 0.2 and 2.5 mm in diameter. Their surface is usually smooth, though occasionally it may become warty. The texture is cartilaginous, similar to firm jelly.
The species in its strict sense (sensu stricto) is characterised by large, pale pinkish brown basidiomata that may sometimes become darker. These typical forms can be distinguished from other members of the species complex by this consistent colouration and size, though some specimens may darken due to parasitic fungi.
The development of these structures follows a characteristic pattern. The infection begins in the outer protective layer () of the host lichen, where it triggers changes in the host's own thread-like structures (hyphae). The first visible signs are pale to reddish spots on the lichen's surface, where the number of algal cells is already reduced. As the fungus grows upward through the host's cortex, it begins producing reproductive structures, eventually forming a mature gall that lacks algal cells entirely.
The internal structure of these growths consists of microscopic threads called hyphae, which measure 2-3 μm in width. These hyphae have uniform walls and lack specialised connecting structures known as clamp connections. The fungus connects to its host through specialised feeding structures called haustorial branches. These consist of a rounded "mother cell" measuring 2.5–4.5 μm in diameter, from which extends a very fine filament 0.5–1 μm thick and 3–7 μm long.
The reproductive layer, called the hymenium, appears clear or colourless under the microscope, though it may sometimes show a reddish-brown colouration in its upper portion. This layer contains numerous probasidia, which are early stages of the reproductive structures. The mature reproductive structures, called basidia, are club-shaped to nearly cylindrical and divided by 1–3 cross-walls. They measure 20–44 μm long by 3–6.5 μm wide. From these basidia emerge long, thin extensions called epibasidia, which can reach up to 85 μm in length while maintaining a width of 2–3 μm.
The spores produced by B. usnearum are nearly spherical to oval-shaped, with a distinctive projection point called an apiculum. They measure 4.5–8 μm long by 4–7.5 μm wide. The fungus also produces an asexual reproductive form (anamorph) that creates long, branching chains of clear, oval-shaped cells measuring 3–5 by 2–3.5 μm.
When B. usnearum infects a host lichen, it often causes a characteristic bending or curving of the lichen's branches at the point of infection. The fungus preferentially infects young and growing parts of the host, particularly branch tips, fibrils (small branches), and areas beneath developing reproductive structures. Notably, when the fungus infects a part of the lichen, it suppresses the production of usnic acid, a characteristic lichen compound, in the infected area. While the fungus is most commonly found growing on various species of Usnea lichens worldwide, it has also been documented on the related genus Protousnea. Interestingly, it has never been found on Usnea species from the subgenus Neuropogon, suggesting some degree of host specificity. Field observations have shown that when multiple Usnea species grow together, not all species are equally susceptible to infection by B. usnearum.
Advanced microscopic imaging techniques reveal that in mature galls of B. usnearum, the basidia are situated at the surface of the gall, while infective hyphae with haustoria are abundant in the central zone and extend to a lesser degree into the basal layers. When stained with special dyes, the fungal cells show a distinctive orangish colour that distinguishes them from the greenish host cells. This structured organization differs from some other gall-forming lichenicolous fungi, like Tremella cetrariicola, where the parasitic hyphae are distributed more evenly throughout the gall.
Habitat and distribution
Biatoropsis usnearum sensu stricto is found growing specifically on six Usnea species: U. subfloridana, U. barbata, U. cavernosa, U. florida, U. glabrescens, and U. intermedia. The species has been confirmed from several locations in Europe (Austria, Finland, Poland, Sweden, and Scotland) and North America (Alberta and British Columbia in Canada, Minnesota in USA). However, its true distribution is likely more extensive than currently documented. Many historical records and reported locations for this species need to be reevaluated, as specimens previously identified as B. usnearum may represent other species in the complex.
Research suggests there may be patterns in how these fungi have evolved to interact with their hosts – lichenicolous fungi that are phylogenetically related to lichens themselves tend to target the algal symbionts in lichen associations, while those from primarily non-lichenised fungal groups (like B. usnearum) appear better adapted to parasitising the fungal component of the lichen.
The fungus preferentially infects young and growing parts of the host, particularly branch tips, fibrils (small branches), and areas beneath developing reproductive structures. Notably, when the fungus infects a part of the lichen, it suppresses the production of usnic acid, a characteristic lichen compound, in the infected area.
References
Tremellomycetes
Fungus species
Fungi described in 1934
Lichenicolous fungi
Taxa named by Veli Räsänen | Biatoropsis usnearum | [
"Biology"
] | 2,419 | [
"Fungi",
"Fungus species"
] |
78,700,040 | https://en.wikipedia.org/wiki/Consalazinic%20acid | Consalazinic acid is a chemical compound with the molecular formula . It is classified as a depsidone and is a secondary metabolite produced by a variety of lichens.
Consalazinic acid was first isolated from Parmotrema subisidiosum and described in 1980. It has since been identified in many other lichens.
References
Lactones
Lichen products
Polyphenols
Heterocyclic compounds with 4 rings
Benzodioxepines
Benzofurans | Consalazinic acid | [
"Chemistry"
] | 104 | [
"Natural products",
"Lichen products"
] |
78,700,249 | https://en.wikipedia.org/wiki/Gynocardin | Gynocardin is a chemical compound with the molecular formula . It is classified as a cyanogenic glycoside.
It was first isolated from Gynocardia odorata, from which it gets it name, and characterized in 1905. It has since been found in a variety of other plants, including those in the genus Passiflora (passionflowers).
Gynocardin may contribute to the toxicity of plants that contain it because, like other cyanogenic glycosides, cyanide is formed upon its hydrolysis.
References
Cyanogenic glycosides
Cyclopentenes | Gynocardin | [
"Chemistry"
] | 131 | [
"Organic compounds",
"Organic compound stubs",
"Organic chemistry stubs"
] |
78,700,451 | https://en.wikipedia.org/wiki/C/1850%20Q1%20%28Bond%29 | Bond's Comet, formally known as C/1850 Q1, is a parabolic comet that was observed through telescopes throughout late 1850. It was the only comet discovered independently by American astronomer, George Phillips Bond.
Discovery and observations
The comet was discovered by George Phillips Bond as a "faint, telescopic object" in the constellation Camelopardalis, about 10° north of the star α Per on 29 August 1850. It gradually brightened during the first weeks of September 1850, allowing further observations of the comet to be conducted by various other observatories around the globe. On September 18, Richard Carrington noted that the comet is best seen with a Fraunhofer refractor. The comet reached perihelion on October 19, however the comet was difficult to observe at this time due to its low position in the twilight skies. It was last observed on 14 November 1850.
Initial orbital calculations in the 19th century showed the comet has a weakly-bound parabolic orbit with an orbital period of 46,000 years. Recalculations in 2003 suggested a hyperbolic trajectory instead, based on 103 observations of the comet.
References
External links
Non-periodic comets
Hyperbolic comets | C/1850 Q1 (Bond) | [
"Astronomy"
] | 242 | [
"Astronomy stubs",
"Comet stubs"
] |
78,700,588 | https://en.wikipedia.org/wiki/List%20of%20mutual%20planetary%20eclipses | This is a List of mutual planetary eclipses, including occultations and transits.
Although mutual occultations of planets had been recorded in 581, 1170, 1590, and 1737, the first attempt to list past and future occultations of that nature was not made until 1970 during a manual search for conjunctions, in which Jan Meeus and Michael Walch discovered further occultations in 1522 and 1570, published in 1970. In 1977, Edwin Goffin calculated the occultations of certain planetary combinations for 1000–3000, but the results remained unpublished.
The first table dedicated to mutual planetary occultations was published in 1979 by Steven Albers, who employed a Fortran program to assist in his calculations. This table was extended back in time by Salvo De Meis in 1993. Meeus recalculated mutual occultations for most of this period in 1998, extending it slightly further forward in time, and in the same year the Pluto Project extended it far into the future. The accuracy of more distant dates is suspect, especially for Mercury, but no planet is exempt from error. Despite this, occultation calculations have been carried out to extremely early and late dates.
The visibility of the calculated occultations has been evaluated by multiple authors. The tables have also been revised and extended even further back and forward in time. But no evaluation is complete, and tables have yet to be computed for non-geocentric perspectives, although the concept has been explored more than once. Very close conjunctions, such as that on 25 March -184, have been excluded from the list.
Projected dates are not necessarily accurate before the 8th century BC or far into the future. Going back in time, the Length of Day (LOD) on Earth was shorter, but it is not known exactly how much shorter thanks to a variety of factors still being debated. Earth's LOD difference (ΔT) is slight, but the cumulative time discrepancy from the earliest accurately dated solar eclipses to the time this discrepancy was first noticed is several hours. Because of this difference, the positions of objects in the sky as viewed from a given point on Earth's surface remain uncertain before the beginning of these records. Although there has been much discussion on the relative contributions of these phenomena, no accurate model for extrapolating beyond these early records yet exists.
Notes
Bibliography
References
Astronomical events of the Solar System | List of mutual planetary eclipses | [
"Astronomy"
] | 487 | [
"Astronomical events of the Solar System",
"Astronomical events",
"Solar System"
] |
78,700,929 | https://en.wikipedia.org/wiki/Slickwater | In fracking, slickwater is a hydraulic fracturing proppant primarily composed of 98–99.5% water and sand, with 0.5–2% chemical additives. These additives reduce friction, prevent corrosion, inhibit microbial growth, and improve fluid flow. Injected at high pressure, slickwater creates fractures in rock formations, enhancing oil or gas extraction. It is widely used for its cost-effectiveness and ability to boost hydrocarbon recovery.
References
Hydraulic fracturing | Slickwater | [
"Chemistry"
] | 99 | [
"Petroleum stubs",
"Petroleum technology",
"Petroleum",
"Natural gas technology",
"Hydraulic fracturing"
] |
72,868,640 | https://en.wikipedia.org/wiki/Pirtobrutinib | Pirtobrutinib, sold under the brand name Jaypirca, is an anticancer medication that is used to treat mantle cell lymphoma. It inhibits B cell lymphocyte proliferation and survival by binding and inhibiting Bruton's tyrosine kinase (BTK). It is taken by mouth.
The most common adverse reactions include fatigue, musculoskeletal pain, diarrhea, edema, dyspnea, pneumonia, and bruising. The most common adverse reactions when used to treat chronic lymphocytic leukemia or small lymphocytic leukemia include fatigue, bruising, cough, musculoskeletal pain, COVID-19, diarrhea, pneumonia, abdominal pain, dyspnea, hemorrhage, edema, nausea, pyrexia, and headache.
Pirtobrutinib was approved for medical use in the United States in January 2023, and in the European Union in November 2023.
Medical uses
In the United States, pirtobrutinib is indicated to treat relapsed or refractory mantle cell lymphoma after at least two lines of systemic therapy, including a Bruton's tyrosine kinase (BTK) inhibitor. In December 2023, the US Food and Drug Administration (FDA) expanded the indication for pirtobrutinib to include the treatment of adults with chronic lymphocytic leukemia or small lymphocytic leukemia.
In the European Union, pirtobrutinib is indicated for the treatment of mantle cell lymphoma.
Mechanism of action
B cells are white cells of the lymphocyte subtype that produce antibodies, but when some of them grow uncontrollably they can be a cause of cancer. A key enzyme in B cell stimulation and survival is BTK, and pirtobrutinib inhibits BTK in a way that is different from the prototypical BTK inhibitor ibrutinib by binding in a different way that avoids a genetic change (mutation at active site cysteine residue C481 in BTK) that can make some tumors less responsive to ibrutinib.
History
Pirtobrutinib is manufactured by Eli Lilly and Company and was approved by the US Food and Drug Administration in January 2023, for the treatment of mantle cell lymphoma that has become refractory to other BTK inhibitors.
Efficacy was evaluated in BRUIN (NCT03740529), an open-label, multicenter, single-arm trial of pirtobrutinib monotherapy that included 120 participants with mantle cell lymphoma previously treated with a Bruton's tyrosine kinase (BTK) inhibitor. Participants had a median of three prior lines of therapy, with 93% having two or more prior lines. The most common prior Bruton's tyrosine kinase inhibitors received were ibrutinib (67%), acalabrutinib (30%), and zanubrutinib (8%); 83% had discontinued their last Bruton's tyrosine kinase inhibitor due to refractory or progressive disease. The trial was conducted at 49 sites in 10 countries in the United States, Europe, Australia, and Asia. The same trial was used to assess safety and efficacy.
Efficacy was evaluated in BRUIN (NCT03740529], an open-label, international, single-arm, multicohort trial that included 108 participants with chronic lymphocytic leukemia or small lymphocytic lymphoma previously treated with at least two prior lines of therapy, including a Bruton's tyrosine kinase (BTK) inhibitor and a B-cell lymphoma-2 (BCL-2) inhibitor. Participants received a median of five prior lines of therapy (range: 2 to 11). Seventy-seven percent of participants discontinued the last BTK inhibitor for refractory or progressive disease. Pirtobrutinib was administered orally at 200 mg once daily and was continued until disease progression or unacceptable toxicity.
Society and culture
Legal status
In April 2023, the Committee for Medicinal Products for Human Use (CHMP) of the European Medicines Agency (EMA) adopted a positive opinion, recommending the granting of a conditional marketing authorization for the medicinal product Jaypirca, intended for the treatment of relapsed or refractory mantle cell lymphoma (MCL). The applicant for this medicinal product is Eli Lilly Nederland B.V. Pirtobrutinib was approved for medical use in the European Union in November 2023.
References
Further reading
External links
Tyrosine kinase inhibitors
Drugs developed by Eli Lilly and Company
Orphan drugs
Methoxy compounds
Amides
Amines
Fluoroarenes
Trifluoromethyl compounds
Carboxamides
Pyrazoles | Pirtobrutinib | [
"Chemistry"
] | 1,030 | [
"Amines",
"Amides",
"Bases (chemistry)",
"Functional groups"
] |
72,869,020 | https://en.wikipedia.org/wiki/List%20of%20Alexander%20McQueen%20collections | British designer Alexander McQueen designed 36 womenswear collections under his eponymous fashion label during a career that lasted from 1992 until his death in 2010. As a designer, McQueen was known for sharp tailoring, historicism, and imaginative designs that often verged into the controversial. His runway shows were known for being dramatic and theatrical, with some including elements of performance art. McQueen drew inspiration for his clothing and shows from a broad range of sources, including film, history, nature, world religions, art, and his own life. Through his work, he explored themes such as romanticism, sexuality, and death.
He used unusual cuts and silhouettes to play with the human form, making wearers appear inhuman. Early in his career, he originated an extreme low-rise trouser cut called the "bumster", which became a brand signature. Other significant designs include the skull scarf, another brand signature, and the armadillo shoe, often worn by singer Lady Gaga.
Womenswear was the focus of McQueen's career. In his early collections, he sometimes presented menswear or had male models walk in the shows, but his label did not have a regular menswear line until 2004. From 1996 to October 2001, McQueen was – in addition to his responsibilities for his own label – head designer at French fashion house Givenchy, for which he produced both haute couture and ready-to-wear collections each season. This article concerns itself with McQueen's own-label womenswear collections.
Collections
Notes
References
Bibliography
1900s fashion
2000s fashion
2010s fashion
Alexander McQueen collections
Alexander McQueen collections
Alexander McQueen collections | List of Alexander McQueen collections | [
"Engineering"
] | 328 | [
"Design-related lists",
"Design"
] |
72,871,641 | https://en.wikipedia.org/wiki/Centroneuralia | Centroneuralia is a proposed clade of animals with bilateral symmetry as an embryo, consisting of the Chordata and Protostomia, united by the presence of a central nervous system. An alternative to the traditional protostome-deuterostome dichotomy, it has found weak support in several studies. Under this hypothesis, Centroneuralia would be sister to Xenambulacraria (Xenacoelomorpha + Ambulacraria) at the base of Bilateria.
Centroneuralia, as a proposed clade, originates in phylogenomics. More precisely, recent studies correlate support for Deuterostomia with simpler, site-homogeneous models, while more sophisticated and site-heterogeneous models recover Centroneuralia more often.
Phylogeny
References
Controversial taxa
Bilaterian taxa | Centroneuralia | [
"Biology"
] | 175 | [
"Biological hypotheses",
"Controversial taxa"
] |
72,872,939 | https://en.wikipedia.org/wiki/Alison%20Buchan | Alison Buchan is the Carolyn Fite Professor at the University of Tennessee. She is known for her work on bacteria in natural environments, especially bacteria within the Roseobacter group. In 2022 she was named as a fellow of the American Academy of Microbiology.
Education and career
Buchan received a B.Sc. from James Madison University in 1994. She then moved to the University of Georgia where she earned a M.Sc. (1997) and a Ph.D. (2001). She was a postdoctoral investigator at Yale University from 2003 until 2005 at which point she moved to the University of Tennessee. In 2016 she was promoted to professor, and as of 2022 she is the Carolyn Fite Professor.
Research
Buchan's early research examined biochemical pathways used by Roseobacter, a common marine bacteria, and the chemical compounds used by Roseobacter as they grow on surfaces. Buchan's research revealed how viruses change the chemical compounds released by bacteria and how heterotrophic bacteria alter the organic carbon produced by marine phytoplankton. She has also examined the interactions between Roseobacter and the viruses that infect them.
Selected publications
Awards and honors
In 2022 Buchan was elected a fellow of the American Academy of Microbiology, and received the 2022 faculty achievement award from the University of Tennessee.
References
External links
Living people
Women microbiologists
Women chemists
Ecologists
University of Georgia alumni
James Madison University alumni
University of Tennessee faculty
Fellows of the American Academy of Microbiology
Year of birth missing (living people) | Alison Buchan | [
"Environmental_science"
] | 319 | [
"Ecologists",
"Environmental scientists"
] |
72,874,947 | https://en.wikipedia.org/wiki/Phosalacine | Phosalacine is a natural antimicrobial and herbicidal compound that has been isolated from the Actinobacteria Kitasatosporia phosalacinea.
It is a tripeptide consisting of the amino acids glufosinate (phosphinothricin), alanine, and leucine. It is similar in structure to bialaphos, differing by replacement of the terminal alanine with leucine.
Phosalacine has antimicrobial activity against Gram-positive and Gram-negative bacteria and some fungi. It also shows herbicidal activity against alfalfa. It is believed that the herbicidal activity is due to the slow release of glufosinate, which is a commercially-used broad spectrum herbicide.
References
Herbicides
Tripeptides
Phosphinic acids | Phosalacine | [
"Biology"
] | 176 | [
"Herbicides",
"Biocides"
] |
72,876,243 | https://en.wikipedia.org/wiki/Lomonosov%27s%20invariant%20subspace%20theorem | Lomonosov's invariant subspace theorem is a mathematical theorem from functional analysis concerning the existence of invariant subspaces of a linear operator on some complex Banach space. The theorem was proved in 1973 by the Russian–American mathematician Victor Lomonosov.
Lomonosov's invariant subspace theorem
Notation and terminology
Let be the space of bounded linear operators from some space to itself. For an operator we call a closed subspace an invariant subspace if , i.e. for every .
Theorem
Let be an infinite dimensional complex Banach space, be compact and such that . Further let be an operator that commutes with . Then there exist an invariant subspace of the operator , i.e. .
Citations
References
Banach spaces
Functional analysis
Operator theory
Theorems in functional analysis | Lomonosov's invariant subspace theorem | [
"Mathematics"
] | 163 | [
"Theorems in mathematical analysis",
"Functions and mappings",
"Functional analysis",
"Mathematical objects",
"Theorems in functional analysis",
"Mathematical relations"
] |
72,876,288 | https://en.wikipedia.org/wiki/GT%20Muscae | GT Muscae, also known as 12 Muscae, is a variable star about 400 light years from the Earth, in the constellation Musca. It is a 5th magnitude star, so it should be faintly visible to the naked eye of an observer far from city lights. It is a quadruple star system, consisting of a spectroscopic binary containing an RS Canum Venaticorum variable (RS CVn) star (HD 101379), orbiting an eclipsing binary (HD 101380). It varies in brightness from magnitude 4.96 to 5.23. GT Muscae is a very active X-ray source.
In 1929, Willem van den Bos discovered that GT Muscae is a visual double star, whose A (HD 101379) and B (HD 101380) components were separated by 0.2 arc seconds at the time he observed it. Examining photographic plates in 1964, Wolfgang Strohmeier et al. discovered that GT Muscae is a variable star. In 1979, based on spectroscopic features, Edward Weiler and Robert Stencel listed GT Muscae as a likely RS CVn variable. Eclipses of the HD 101380 pair were first reported by Andrew Collier Cameron in his 1982 PhD thesis, in which he also determined that pair's orbital period. The entire star system was given the variable star designation GT Muscae in 1988.
Strong, variable, 5 GHz radio emission from GT Muscae, indicative of flares, was detected in 1982 and was interpreted as indicating high levels of chromospheric and coronal activity.
GT Muscae was detected in the early observations of the Uhuru X-ray satellite, originally denoted as 2U 1134–161, later renamed 4U 1137–65. Michael Garcia et al. identified HD 101379 as the source seen by Uhuru, in 1980. During the 2010-2019 decade, GT Muscae showed the most X-ray flare activity of any star in the sky, producing flares with energies as high as ~1038 ergs.
References
Musca
56862
101379
Muscae, GT
4492
Algol variables
RS Canum Venaticorum variables
X-ray binaries
G-type giants
A-type main-sequence stars | GT Muscae | [
"Astronomy"
] | 481 | [
"Musca",
"Constellations"
] |
72,876,407 | https://en.wikipedia.org/wiki/Fax%C3%A9n%20integral | In mathematics, the Faxén integral (also named Faxén function) is the following integral
The integral is named after the Swedish physicist Olov Hilding Faxén, who published it in 1921 in his PhD thesis.
n-dimensional Faxén integral
More generally one defines the -dimensional Faxén integral as
with
and
for and
The parameter is only for convenience in calculations.
Properties
Let denote the Gamma function, then
For one has the following relationship to the Scorer function
Asymptotics
For we have the following asymptotics
References
Mathematical analysis
Functions and mappings
Definitions of mathematical integration | Faxén integral | [
"Mathematics"
] | 124 | [
"Mathematical objects",
"Mathematical analysis",
"Mathematical relations",
"Functions and mappings"
] |
72,876,414 | https://en.wikipedia.org/wiki/HD%2029399 | HD 29399 is a binary star in the constellation Reticulum. With an apparent visual magnitude of 5.78, it is visible to the naked eye under good viewing conditions. From its parallax measured by the Gaia, it is located at a distance of 144 light-years (44 parsecs) from Earth.
This star is a K-type giant with an spectral type of K1III. Its magnitude 9.2 companion is located at a separation of . In 2022, a gas giant planet was discovered via the radial velocity method orbiting the primary star.
Star system
HD 29399 is a K-type giant star with a spectral type of K1III, which indicates it is an evolved star that has ceased hydrogen fusion in its nucleus and left the main sequence. Its main properties were inferred with high precision from an asteroseismology model created with photometric data acquired by the TESS spacecraft, which observed HD 29399 almost continuously for one year during its primary mission. HD 29399 has a mass of , radius of , and an age of about 6.2 billion years. It is shining with a bolometric luminosity of about , and an effective temperature of 4,850 K. Its metallicity, the proportion of elements other than hydrogen and helium, is slightly higher than the solar value, with an iron abundance 40% greater than the Sun's.
HD 29399 is part probably of a binary system with a magnitude 9.2 star at an angular separation of 31.9 arcseconds. Astrometric data obtained by the Gaia spacecraft have confirmed that both stars have similar proper motions and distances from Earth. This star has an estimated mass of , luminosity of , and effective temperature of 4,900 K.
Planetary system
This star was included in the Pan-Pacific Planet Search, which used the Anglo-Australian Telescope to search for exoplanets around giant stars in the southern hemisphere. A 2017 study, analyzing data from HD 29399 obtained in this survey, discovered a 765-day periodic signal in the star's radial velocity, which could be caused by an orbiting planet. However, the authors attributed this signal to a stellar magnetic cycle, reporting a periodicity in the star's light curve and a possible correlation between the radial velocity and the equivalent width of the Hα line, which both point to stellar activity being the cause of the signal. A 2022 study, using additional observations by the CORALIE spectrograph at the Leonhard Euler Telescope, confirmed the presence a 900-day signal in the star's radial velocity, and did not find evidence to support an stellar activity origin for this signal, concluding that a planet is the most likely explanation.
The planet, designated HD 29399 b, is a gas giant with a minimum mass of 1.6 . Since the radial velocity method used in its discovery measures only the star's motion along the line of sight to Earth, the orbital inclination is unconstrained, and the planet's true mass cannot be determined. HD 29399 b takes 893 days to complete an orbit and is located at a distance of 1.91 AU from its star, which is far enough for its orbit to be unaffected by tidal forces at any point of the star's evolution. Its orbital eccentricity is small and the data are consistent with a circular orbit.
The orbital solution for HD 29399 includes a linear trend, indicating the existence of an additional body in the system. The current data are consistent with a second giant planet with a period of the order of decades, although nothing can be said with certainty about such object yet.
References
K-type giants
Reticulum
Durchmusterung objects
29399
21253
1475
Binary stars
Planetary systems with one confirmed planet | HD 29399 | [
"Astronomy"
] | 781 | [
"Reticulum",
"Constellations"
] |
72,877,528 | https://en.wikipedia.org/wiki/HD%20116852 | HD 116852, also known as HIP 65890, is a solitary, whitish-blue-hued star located in the southern circumpolar constellation Chamaeleon. It has an apparent magnitude of 8.47, making it readily visible in binoculars but not to the naked eye. The star is located relatively far at a distance of 6,310 parsecs but is drifting closer with a heliocentric radial velocity of . At its current distance, HD 116852's brightness is diminished by 0.67 magnitudes due to extinction from interstellar dust. It has an absolute bolometric magnitude of −9.0.
HD 116852 has a stellar classification of O8.5 II-III ((f)), indicating that it is an evolved O-type star with a luminosity class intermediate between a bright giant and a regular giant star. The spectrum also includes a strong He II absorption accompanied by weak N III emissions. It has 15 times the mass of the Sun and 19 times the solar radius. It radiates a bolometric luminosity 16,187 times greater than the Sun from its photosphere at an effective temperature of . HD 116852 is metal deficient ([Fe/H] = −0.20) and is estimated to be 5 million years old. Like many hot stars the object spins rapidly, having a projected rotational velocity of .
There is a cloud of highly ionized gas in the line-of-sight towards HD 116852. It was first noticed by astronomers Kenneth R. Sembach and Blair D. Savage in 1994. The cloud in question contains an overabundance of carbon including other chemical elements such as silicon, phosphorus, nickel, and germanium. HD 116852 has a high galactic latitude, indicating that it is currently in the galactic halo between the Scutum-Centaurus Arm and the Sagittarius-Carina Arm. It is most likely a runaway star that was ejected from its birthplace into its current location.
References
O-type giants
O-type bright giants
Runaway stars
Chamaeleon
CD-78 00545
116852
065890 | HD 116852 | [
"Astronomy"
] | 448 | [
"Chamaeleon",
"Constellations"
] |
72,878,382 | https://en.wikipedia.org/wiki/Dipropyltin%20dichloride | Dipropyltin dichloride is an organotin compound with the chemical formula . It is a white solid. This chemical belongs to a subclass of organotin compounds called diorganotin dihalides (, where R is organyl and X is a halogen).
Uses
Dipropyltin dichloride has broad applications in industry and laboratory. It can be used as a polyvinyl chloride stabilizer, fungicide and insecticide.
Hazards and toxicity
Dipropyltin dichloride can be absorbed through skin, causing intoxication. It irritates skin, eyes and respiratory system. It is toxic if swallowed. It is suspected this chemical is a human mutagen and teratogen, and toxic to the reproductive system.
Dipropyltin dichloride may react violently with strong oxidizing agents. Upon catching fire, irritating and toxic fumes, gases and smokes are released, like carbon monoxide (CO), carbon dioxide (), tin(II) oxide (SnO), tin(IV) oxide () and hydrogen chloride (HCl).
References
Organotin compounds | Dipropyltin dichloride | [
"Chemistry"
] | 238 | [
"Organic compounds",
"Organic compound stubs",
"Organic chemistry stubs"
] |
72,882,323 | https://en.wikipedia.org/wiki/Journal%20of%20Hazardous%20Materials | The Journal of Hazardous Materials is a peer-reviewed, scientific journal that covers the study of hazardous materials and their impact on the environment. The journal is published by Elsevier and was established in 1975. Since 2022, the editor-in-chief is Zhen He (Washington University in St. Louis). The journal publishes original research articles, review articles, and short communications.
Abstracting and indexing
The journal is abstracted and indexed in:
According to the Journal Citation Reports, the journal has a 2021 impact factor of 14.224.
References
External links
Materials science journals
English-language journals
Elsevier academic journals
Academic journals established in 1975
Journals published between 13 and 25 times per year | Journal of Hazardous Materials | [
"Materials_science",
"Engineering"
] | 140 | [
"Materials science journals",
"Materials science"
] |
72,882,431 | https://en.wikipedia.org/wiki/Energy%20and%20Buildings | Energy and Buildings is a semi-monthly peer-reviewed scientific journal that covers all aspects of energy use in buildings and their impact on the environment. The journal is published by Elsevier and was established in 1977. The editors-in-chief are Jianlei Niu (Hong Kong Polytechnic University) and Mat Santamouris (University of New South Wales).
The journal publishes original research articles, review articles, and short communications.
Abstracting and indexing
The journal is abstracted and indexed in:
According to the Journal Citation Reports, the journal has a 2022 impact factor of 6.7.
References
External links
Energy and fuel journals
English-language journals
Elsevier academic journals
Semi-monthly journals
Academic journals established in 1977 | Energy and Buildings | [
"Environmental_science"
] | 146 | [
"Environmental science journals",
"Energy and fuel journals"
] |
72,883,255 | https://en.wikipedia.org/wiki/S%2CS%27-Dimethyl%20dithiocarbonate | {{DISPLAYTITLE:S,S-Dimethyl dithiocarbonate}}
{{Chembox
| Name = S,S'''-Dimethyl dithiocarbonate
| IUPACName = S,S-Dimethyl dithiocarbonate
| SystematicName = S,S-Dimethyl carbonodithioate
| OtherNames = {{ubl|Bis(methylsulfanyl)methanone|Carbonodithioic acid S,S-dimethyl ester|Dithiocarbonic acid S,S-dimethyl ester|S,S-Dimethyl dithiocarbonate}}
| ImageFile = S,S'-Dimethyl dithiocarbonate.png
| ImageAlt = S,S'-Dimethyl dithiocarbonate molecule
| Section1 =
| Section2 =
| Section7 =
| Section9 =
}}S,S-Dimethyl dithiocarbonate is an organic compound with the chemical formula . It is a colorless liquid. It is a methyl ester of dithiocarbonic S,S-acid (). It is a thioester (the prefix thio- means that an oxygen atom in the compound is replaced by a sulfur atom). It is an analog of dimethyl carbonate (), where the two oxygen atoms from the groups are replaced by sulfur atoms. In terms of the name of this thioester, it is derived from an esterification of dithiocarbonic S,S-acid with methanethiol.
UsesS,S'-Dimethyl dithiocarbonate is used as a dehydrating agent in chemistry and as a carbonylating agent. It can be used as a source of a methanethiolate (CH3S−).
[[Image:Alkanethiolation reaction.png|thumb|center|500px|Alkanethiolation reaction using S,S'-dimethyl dithiocarbonate, tetrabutylammonium bromide and aqueous solution of potassium hydroxide]]
Hazards and toxicityS,S′-Dimethyl dithiocarbonate is a skin, eye, and respiratory system irritant; it can be absorbed into the body through the skin, causing damage to the body. It may cause damage to gastrointestinal system if it is swallowed. S,S′''-Dimethyl dithiocarbonate is combustible. Upon catching fire, irritating and toxic fumes and gases, such as carbon monoxide (CO), carbon dioxide (), and sulfur dioxide (), are released. It may react violently with strong oxidizing agents.
References
Organosulfur compounds
Thiocarbonyl compounds | S,S'-Dimethyl dithiocarbonate | [
"Chemistry"
] | 593 | [
"Organic compounds",
"Organosulfur compounds"
] |
72,883,371 | https://en.wikipedia.org/wiki/Trend%20periodic%20nonstationary%20processes | Trend periodic non-stationary processes (or trend cyclostationary processes) are a type of cyclostationary process that exhibits both periodic behavior and a statistical trend. The trend can be linear or nonlinear, and it can result from systematic changes in the data over time. A cyclostationary process can be formed by removing the trend component. This approach is utilized in the analysis of the trend-stationary process.
In data analysis classification of periodic data into stationary-periodic, trend-periodic and stochastic-periodic time series is achieved by means of phase dispersion minimization (PDM) test, which is a method for identifying periodicity.
Applications
Trending cyclostationary processes have several applications in finance, engineering, economics, and environmental research. Trending cyclostationary processes are used in economics to predict the seasonality and trend of time series data that display both periodic and trending behavior, such as rail and air travel demand. Trending cyclostationary processes are used in engineering to simulate signals that display both periodic and trending behavior, such as signals in modulated radio communications or control systems. Trending cyclostationary processes are used in economics to represent time series data that display both periodic behavior and trends in which the trend is usually represented by a so-called unit root
in the autoregressive part of the model. Trending cyclostationary processes are used in environmental research to simulate time series data that display both periodic behavior and trends, such as temperature or pollutant appearance patterns. In fact, almost any pollutions related phenomena falls into one of stochastic, periodic-stochastic, or trend-period-stochastic processes.
Properties
Trending cyclostationary processes have traits that are a mix of cyclostationary processes and trends. Trending cyclostationary processes have second-order stationarity, which means that their second-order moments are time-periodic. They do, however, display non-stationarity, which means that their mean and variance alter over time as a result of the presence of the trend.
A trend periodic stationary process is a sort of stationary time series data that has a consistent underlying trend that repeats itself regularly. A Fourier series expansion is a popular mathematical depiction of a trend periodic stationary process:
where x(t) is the time series data, T is the period of the trend, is the mean of the series, and are the Fourier coefficients, and k is the harmonic number.
Another way to represent trend periodic stationary processes is by using a regression model with a sine and cosine function, such as:
where , , , and are the regression coefficients that can be estimated using statistical methods.
Decomposing the signal is widely used to separate the trend process from the periodic one and represent the periodic part as sinusoid functions. The spectral density estimation is one of the methods used for this purpose. The decomposed function of the periodic trend process has a trend and a principal function that governs the periodicity.
Example
An example of trend periodic in the second form is
where 10t is trend and plus the sinusiduals are periodic stationary processes.
Detection and estimation
Estimation and detection of trending cyclostationary processes are more difficult than for standard cyclostationary processes due to discrepancies in trend definitions. One popular strategy is to first remove the trend from the data before estimating and detecting cyclostationary processes. Another strategy is to represent the data as a cyclostationary process and a trend and estimate the parameters of both components at the same time.
References
Statistical signal processing | Trend periodic nonstationary processes | [
"Engineering"
] | 756 | [
"Statistical signal processing",
"Engineering statistics"
] |
72,884,770 | https://en.wikipedia.org/wiki/Albicidin | Albicidin is an antibiotic and phytotoxic molecule produced by the bacterium Xanthomonas albilineans which infects sugarcane causing leaf scald.
As a phytotoxin, it acts by inhibiting the differentiation of chloroplasts. It accomplishes this by inhibiting DNA gyrase, and thereby preventing the replication of chloroplast DNA. As such it plays a major role in leaf scald disease.
As a DNA gyrase inhibitor, albicindin also has potential therapeutic use as an antibiotic. Its antibiotic properties were discovered in the early 1980s, when the molecule was isolated and purified from cultures of Xanthomonas albilineans. However, the precise structure of the molecule was only identified in 2015. A laboratory synthesis of albicidin has been developed, and research is currently focused on the design and evaluation of synthetic derivatives of albicidin with improved properties.
References
Plant toxins
Antibiotics
Benzamides
Nitriles | Albicidin | [
"Chemistry",
"Biology"
] | 212 | [
"Chemical ecology",
"Biotechnology products",
"Biocides",
"Functional groups",
"Plant toxins",
"Antibiotics",
"Nitriles"
] |
72,885,437 | https://en.wikipedia.org/wiki/Mars%20Year%201 | Mars Year 1 is the first year of Martian timekeeping standard developed by Clancy et al. originally for the purposes of working with the cyclical temporal variations of meteorological phenomena of Mars, but later used for general timekeeping on Mars. Mars Years have no officially adopted month systems. Scientists generally use two sub-units of the Mars Year:
the Solar longitude (Ls) system: 360 degrees per Mars Year that represent the position of Mars in its orbit around the Sun, or
the Sol system: 668 sols per Mars Year. This system consists of uniform time units. However, Mars Year sols may be confused with rover mission times that are also expressed in sols.
Unlike in the day vs. sol distinction, "Mars Year" has no unique Latin term. Start and End dates of Mars Years were determined for 1607–2141 by Piqueux et al. Earth and Mars dates can be converted in the Mars Climate Database, however, the Mars Years are only rational to apply to events that take place on Mars.
Mars Year 1 started on 11 April 1955 and ended on 25 February 1957. Mars Year 1 is preceded by Mars Year 0.
Events of Mars Year 1
There was no spacecraft on or around Mars in Mars Year 1 (the first successful flyby occurred in Mars Year 6).
De Mottoni created two albedo maps, Kuiper made several drawings Millman made maps and detailed descriptions and Dollfus observed the poles of Mars during the 1956 opposition.
Ls 257 (Sol 495) Křivský et al. reports that the polar cap disappeared during a solar flare event.
Ls 263 (Sol 505): Earth is closest to Mars (10 September 1956). This was the best time to observe Mars, therefore most observations during M.Y. 1 took place during this time.
Around Ls 270: Major dust storm. Kuiper observed that a new polar cap formed before the southern summer solstice (Ls 270), and a dust storm developed over Mare Sirenum or Hellespontus and spread rapidly, covering the entire planet with dust except the south polar region. The lowered temperature may have led to the early formation of the polar cap where bright white snow was observed uncontaminated by yellow dust, however Millman attributes the disappearance of the cap to clouds.
References
Mars
Mars
Calendar eras | Mars Year 1 | [
"Physics"
] | 475 | [
"Spacetime",
"Timekeeping",
"Physical quantities",
"Time"
] |
77,296,663 | https://en.wikipedia.org/wiki/Greg%20Quicke | Greg Quicke (1961 – 7 June 2024) was an Australian amateur astronomer, astronomy tour operator and author who became known from his appearances on the Australian Broadcasting Corporation (ABC) and British Broadcasting Corporation (BBC) Stargazing Live TV specials, beginning in April 2017. He was nicknamed 'Space Gandalf'.
Quicke also had his own television series on Australia's ABC, the ten part A Stargazer's Guide to the Cosmos.
Quicke died on 7 June 2024, at the age of 62.
References
External links
1961 births
2024 deaths
21st-century Australian astronomers | Greg Quicke | [
"Astronomy"
] | 123 | [
"Astronomers",
"Astronomer stubs",
"Astronomy stubs"
] |
77,297,515 | https://en.wikipedia.org/wiki/Jane%20Egerton-Idehen | Jane Egerton-Idehen is a Nigerian engineer and the MD/CEO of Nigerian Communications Satellite limited (NIGCOMSAT), a federal agency under the Nigerian Federal Ministry of Communications, Innovation and Digital Economy.
Education
Egerton-Idehen was born in Ajegunle, Lagos. She studied electronics engineering at the University of Nigeria from 1995 and graduated in 2001 with a Bachelor of Engineering degree. In 2007, she started her postgraduate studies at Warwick Business School and graduated with a Master of Business Administration degree in 2010.
Career
Egerton-Idehen started her career as an earth station engineer at Spar Aerospace Limited in Lagos, Nigeria right after graduating from university. She moved on to Ericsson, Nigeria as a Product Manager in 2003 and became a Sales Manager in 2005. In 2008, she became the Accounts manager, until her departure in 2010. She joined Nokia Siemens Networks in 2010 as the customer team head in Nigeria until 2012. She returned to Ericsson in 2012 and stayed there till 2017, before joining Avanti as Country Manager Nigeria and Regional Sales Manager West Africa at Avanti Communications.
She left Avanti in 2021 and became the Head of Sales, the Middle East and Africa for Meta (Facebook) from 2021 until her appointment as MD/CEO of NIGCOMSAT in October 2023.
Nigerian Communications Satellite
Jane Egerton-Idehen was appointed the MD/CEO of Nigerian Communications Satellite Limited (NIGCOMSAT) by President Bola Tinubu in October 2023. She replaced Tukur Funtua.
References
Nigerian women engineers
Nigerian women
Electronics engineers
Year of birth missing (living people)
Living people | Jane Egerton-Idehen | [
"Engineering"
] | 335 | [
"Electronics engineers",
"Electronic engineering"
] |
77,297,562 | https://en.wikipedia.org/wiki/NGC%201396 | NGC 1396 is a dwarf elliptical galaxy located 61 million light years away in the constellation of Fornax. The galaxy was discovered by astronomer Julius Schmidt on January 19, 1865, and is a member of the Fornax Cluster. Despite the fact that the galaxy PGC 13398 is most commonly identified as NGC 1396, there is uncertainty in its identification.
NGC 1396 is a satellite galaxy of NGC 1399.
232 known globular clusters have been observed surrounding NGC 1396, along with a central nuclear star cluster with an estimated mass of 9.6 × 106 M☉.
NGC 1396 has a metallicity of [Fe/H]∼ -0.4, with unusually overabundant values of [Ca/Fe] ∼+ 0.1, and underabundant sodium, with [Na/Fe] values around -0.1, while [Mg/Fe] is overabundant throughout the galaxy, increasing at a greater distance from the center of the galaxy. These abundance ratios compared with galaxies in the Local Group, show that the chemical enrichment history of the interstellar medium of NGC 1396 is similar to the galactic disc of the Milky Way. This implies that NGC 1396 originated as a progenitor galaxy the size of the Large Magellanic Cloud that lost its gas as it fell though the Fornax Cluster.
See also
List of NGC objects (1001–2000)
Messier 32
Messier 110
External links
References
1396
013398
Fornax
Astronomical objects discovered in 1865
Dwarf elliptical galaxies
Fornax Cluster | NGC 1396 | [
"Astronomy"
] | 322 | [
"Fornax",
"Constellations"
] |
77,298,068 | https://en.wikipedia.org/wiki/Landau%E2%80%93Peierls%20instability | Landau–Peierls instability refers to the phenomenon in which the mean square displacements due to thermal fluctuatuions diverge in the thermodynamic limit and is named after Lev Landau (1937) and Rudolf Peierls (1934). This instability prevails in one-dimensional ordering of atoms/molecules in 3D space such as 1D crystals and smectics and also in two-dimensional ordering in 2D space such as a monomolecular adsorbed filsms at the interface between two isotrophic phases. The divergence is logarthmic, which is rather slow and therefore it is possible to realize substances (such as the smectics) in practice that are subject to Landau–Peierls instability.
Mathematical description
Consider a one-dimensionally ordered crystal in 3D space. The density function is then given by . Since this is a 1D system, only the displacement along the -direction due to thermal fluctuations can smooth out the density function; displacements in other two directions are irrelevant. The net change in the free energy due to the fluctuations is given by
where is the free energy without flcutuations. Note that cannot depend on or be a linear function of because the first case corresponds to a simple uniform translation and the second case is unstable. Thus, must be quadratic in the derivatives of . These are given by
where , and are material constants; in smectics, where the symmetry must be obeyed, the second term has to be set zero, i.e., . In the Fourier space (in a unit volume), the free energy is just
From the equipartition theorem (each Fourier mode, on average, is allotted an energy equal to ) , we can deduce that
The mean square displacement is then given by
where the integral is cut off at a large wavenumber that is comparable to the linear dimension of the element undergoing deformation. In the thermodynamic limit, , the integral diverges logarthmically. This means that an element at a particular point is displaced through very large distances and therefore smoothes out the function , leaving constant as the only solution and destroying the 1D ordering.
See also
Peierls transition
References
Phases of matter
Statistical mechanics | Landau–Peierls instability | [
"Physics",
"Chemistry"
] | 461 | [
"Statistical mechanics",
"Phases of matter",
"Matter"
] |
77,298,479 | https://en.wikipedia.org/wiki/Distributed%20Artificial%20Intelligence%20Research%20Institute | The Distributed Artificial Intelligence Research Institute (or DAIR Institute) is a research institute founded by Timnit Gebru in December 2021. The institute announced itself as "an independent, community-rooted institute set to counter Big Tech’s pervasive influence on the research, development and deployment of AI."
In February 2023, two other members of Google's Ethical AI research group, researcher Alex Hanna and developer Dylan Baker, left Google to join DAIR.
References
External links
2021 establishments in the United States
Research institutes established in 2021
Artificial intelligence laboratories
Ethics of science and technology | Distributed Artificial Intelligence Research Institute | [
"Technology"
] | 119 | [
"Ethics of science and technology"
] |
77,299,610 | https://en.wikipedia.org/wiki/Shoji%20Nishikawa | Shōji Nishikawa (Japanese: 西川 正治, Nishikawa Shōji, 5 December 1884 – 5 January 1952) was a Japanese physicist and a founding father of crystallography in Japan.
Education and career
Nishikawa was born in 1884 in Hachiōji, Tokyo Prefecture, as the son of an important silk dealer. He grew up in Tokyo and later studied at the Faculty of Science at the Imperial University of Tokyo (now University of Tokyo). His PhD in physics was supervised by Suekichi Kinoshita, with an initial focus on radioactivity. During this time, Nishikawa was inspired by Torahiko Terada to turn his interest turned to crystallography, which was experiencing a worldwide boom with the then new method of X-ray diffraction for structural analysis. The first publications of Nishikawa came out between 1913 and 1915, at a time when the British Nobel Prize winners in physics William Henry Bragg and William Lawrence Bragg were doing groundbreaking pioneering work in this field. Between 1916 and 1919, Nishikawa stayed in the United States and worked at Cornell University, where he was a mentor of the then graduate student Ralph Wyckoff. Before returning to Japan in 1920, Nishikawa also spent six months with William H. Bragg at University College London. Back in Japan, he led the first research group at the Institute of Physical and Chemical Research (now known as RIKEN) and worked there until 1949. In 1924, Nishikawa became a professor at the University of Tokyo, where he worked until his retirement in 1945.
Nishikawa pioneered in the application of space groups in crystal structure determination, using spinel compounds as examples. His other significant scientific contributions include the analysis of the phase transformation of quartz and the experimental evidence of deviations from Friedel's law for certain crystal structures. In 1950, Nishikawa co-founded the Crystallographic Society of Japan and became its first president until his death two years later. One of Nishikawa's students was Seishi Kikuchi, who in 1928 described the Kikuchi lines that appear in electron diffraction and were named after him.
Nishikawa was elected into the Japan Academy in 1937. He received the Japanese Order of Culture in 1951 and was recognized as an honorary citizen of Hachiōji, where he was born.
Personal life
Nishikawa was married to a teacher named Kiku Ayai and they had four sons and a daughter. Both of his two sons later became physicists. The first son, Tetsuji Nishikawa (1926–2010), was one of the founding fathers of The High Energy Accelerator Research Organization (also known as KEK) and was its general director from 1977 to 1989. A younger son, Kyōji Nishikawa (born 1934), is an emeritus professor at the Hiroshima University specialized in nuclear fusion and plasma science. Nishikawa died of apoplexy at his home on January 5, 1952.
References
1884 births
1952 deaths
People from Hachiōji, Tokyo
University of Tokyo alumni
Academic staff of the University of Tokyo
Riken personnel
Crystallographers
20th-century Japanese physicists
X-ray pioneers
Recipients of the Order of Culture
Cornell University people | Shoji Nishikawa | [
"Chemistry",
"Materials_science"
] | 656 | [
"Crystallographers",
"Crystallography"
] |
77,301,785 | https://en.wikipedia.org/wiki/AI%20Safety%20Institute | An AI Safety Institute (AISI), in general, is a state-backed institute aiming to evaluate and ensure the safety of the most advanced artificial intelligence (AI) models, also called frontier AI models.
AI safety gained prominence in 2023, notably with public declarations about potential existential risks from AI. During the AI Safety Summit in November 2023, the United Kingdom (UK) and the United States (US) both created their own AISI. During the AI Seoul Summit in May 2024, international leaders agreed to form a network of AI Safety Institutes, comprising institutes from the UK, the US, Japan, France, Germany, Italy, Singapore, South Korea, Australia, Canada and the European Union.
Timeline
In 2023, Rishi Sunak, the Prime Minister of the United Kingdom, expressed his intention to "make the U.K. not just the intellectual home but the geographical home of global AI safety regulation" and unveiled plans for an AI Safety Summit. He emphasized the need for independent safety evaluations, stating that AI companies cannot "mark their own homework". During the summit in November 2023, the UK AISI was officially established as an evolution of the Frontier AI Taskforce, and the US AISI as part of the NIST. Japan followed by launching an AI safety institute in February 2024.
Politico reported in April 2024 that many AI companies had not shared pre-deployment access to their most advanced AI models for evaluation. Meta's president of global affairs Nick Clegg said that many AI companies were waiting for the UK and the US AI Safety Institutes to work out common evaluation rules and procedures. An agreement was indeed concluded between the UK and the US in April 2024 to collaborate on at least one joint safety test. Initially established in London, the UK AI Safety Institute announced in May 2024 that it would open an office in San Francisco, where many AI companies are located. This is part of a plan to "set new, international standards on AI safety", according to UK's technology minister Michele Donelan.
At the AI Seoul Summit in May 2024, the European Union and other countries agreed to create their own AI safety institutes, forming an international network.
United Kingdom
The United Kingdom founded in April 2023 a safety organisation called Frontier AI Taskforce, with an initial budget of £100 million. In November 2023, it evolved into the UK AISI, and continued to be led by Ian Hogarth. The AISI is part of the United Kingdom's Department for Science, Innovation and Technology.
The United Kingdom's AI strategy aims to balance safety and innovation. Unlike the European Union which adopted the AI Act, the UK is reluctant to legislate early, considering that it may lower the sector's growth, and that laws might be rendered obsolete by technological progress.
In May 2024, the institute open-sourced an AI safety tool called "Inspect", which evaluates AI model capabilities such as reasoning and their degree of autonomy.
United States
The US AISI was founded in November 2023 as part of the NIST. This happened the day after the signature of the Executive Order on Safe, Secure, and Trustworthy Development and Use of Artificial Intelligence. In February 2024, Joe Biden's former economic policy adviser Elizabeth Kelly was appointed to lead it.
In February 2024, the US government created the US AI Safety Institute Consortium (AISIC), regrouping more than 200 organizations such as Google, Anthropic or Microsoft.
In March 2024, a budget of $10 million was allocated. Observers noted that this investment is relatively small, especially considering the presence of many big AI companies in the US. The NIST itself, which hosts the AISI, is also known for its chronic lack of funding. Biden administration's request for additional funding was met with further budget cuts from congressional appropriators.
See also
Alignment Research Center
Foundation model
Regulation of artificial intelligence
References
External links
European AI Office
Japan AI Safety Institute
UK AI Safety Institute
US AI Safety Institute
KR AI Safety Institute
AI safety
Safety organizations
Existential risk from artificial general intelligence | AI Safety Institute | [
"Technology",
"Engineering"
] | 840 | [
"Safety engineering",
"AI safety",
"Existential risk from artificial general intelligence"
] |
77,303,811 | https://en.wikipedia.org/wiki/Staurostoma | Staurostoma is a genus of cnidarians of the family Laodiceidae. The genus contains two described species.
Species
There are two species accepted:
Staurostoma falklandica (Browne, 1907)
Staurostoma mertensii (Brandt, 1835)
References
Cnidarian genera
Marine biology
Taxa named by Ernst Haeckel
Animals described in 1879 | Staurostoma | [
"Biology"
] | 75 | [
"Marine biology"
] |
77,303,957 | https://en.wikipedia.org/wiki/Wilhelm%20Schneider%20%28engineer%29 | Wilhelm Schneider (born May 3, 1938) is an Austrian scientist and a specialist in fluid mechanics. He is an is Emeritus Professor of at TU Wien.
Biography and research
Wilhelm Schneider was born in Vienna, Austria in 1938. He graduated with a doctors' degree from TU Wien in 1963. He then worked at the DFVLR till 1968 and then at the Jet Propulsion Laboratory for a year and then joined the DFVLR in 1969. He moved to TU Wien in 1973 and became an emeritus professor in 2006.
His research contributions are significant in many areas of fluid mechanics and related areas including supersonic and hypersonic flows, radiation gas dynamics, waves in fluids, jets, plumes & shear layers, convection flows, condensation, evaporation, fluidization, electric arcs and other topics.
He became the corresponding member of the Austrian Academy of Sciences in 1989 and a full member in 1995. He also served as the chairman of the academy form 2002 to 2006. He is the receipient of many awards including Ernst Mach prize (1966), Ludwig Prandtl Ring (2005) and others. He became the member of the European Academy of Sciences and Arts in 2011.
On his 60th birthday, an edited book titled Recent Advances in Boundary Layer Theory was published by Springer and on his 70th birthday the book
References
1938 births
Living people
Fluid dynamicists
Members of the European Academy of Sciences and Arts
Members of the Austrian Academy of Sciences
TU Wien alumni | Wilhelm Schneider (engineer) | [
"Chemistry"
] | 296 | [
"Fluid dynamicists",
"Fluid dynamics"
] |
77,304,235 | https://en.wikipedia.org/wiki/North%20Polar%20Spur | The North Polar Spur is one of the largest structures in the Milky Way galaxy. A giant plume of bright, polarised emission, it extends into the northern galactic hemisphere, roughly perpendicular to the galactic plane. It cannot be seen at optical wavelengths, but is visible at radio and xray wavelengths.
It is thought to be produced by ionised gas in a strong magnetic field. Its size, and distance from Earth, are yet to be established.
References
Milky Way
Virgo (constellation) | North Polar Spur | [
"Astronomy"
] | 99 | [
"Virgo (constellation)",
"Galaxy stubs",
"Astronomy stubs",
"Constellations"
] |
77,304,338 | https://en.wikipedia.org/wiki/Andrea%20Friedman%20%28historian%29 | Andrea Friedman is an American historian of gender and sexuality with a focus on the modern United States. She is a professor in the Arts and Sciences at Washington University in St. Louis. Her teaching courses includes US women's and gender history, the history of sexuality, feminist politics, and queer and sexuality studies.
Life
Friedman earned a B.A. (1978) in political science and M.A. (1985) in history from Ohio State University. She completed a Ph.D. (1995) in history at the University of Wisconsin–Madison. Her 1995 dissertation was titled, Prurient Interests: Anti-obscenity Campaigns in New York City, 1909-1945.
Friedman was a lecturer in history at the University of California, Santa Cruz from 1994 to 1996. In 1996, she joined Arts and Sciences at Washington University in St. Louis as an assistant professor of history and women, gender, and sexuality studies. Friedman was promoted to associate professor in 2004 and professor in July 2016. She is the director of the M.A. in women, gender, and sexuality studies and the M.A./J.D. programs director. Friedman is a professor emeritus in the department of history. In 2012, Friedman won the James M. Holobaugh Award for service to the LGBTQIA community.
Selected works
References
Living people
Place of birth missing (living people)
Year of birth missing (living people)
Ohio State University College of Arts and Sciences alumni
University of Wisconsin–Madison College of Letters and Science alumni
Washington University in St. Louis faculty
21st-century American historians
21st-century American women academics
21st-century American academics
Historians of sexuality
Historians of the United States
American women historians | Andrea Friedman (historian) | [
"Biology"
] | 343 | [
"Behavior",
"Sexuality",
"Historians of sexuality"
] |
77,304,698 | https://en.wikipedia.org/wiki/One-step%20method | In numerical mathematics, one-step methods and multi-step methods are a large group of calculation methods for solving initial value problems. This problem, in which an ordinary differential equation is given together with an initial condition, plays a central role in all natural and engineering sciences and is also becoming increasingly important in the economic and social sciences, for example. Initial value problems are used to analyze, simulate or predict dynamic processes.
The basic idea behind one-step methods is that they calculate approximation points step by step along the desired solution, starting from the given starting point. They only use the most recently determined approximation for the next step, in contrast to multi-step methods, which also include points further back in the calculation. The one-step methods can be roughly divided into two groups: the explicit methods, which calculate the new approximation directly from the old one, and the implicit methods, which require an equation to be solved. The latter are also suitable for so-called stiff initial value problems.
The simplest and oldest one-step method, the explicit Euler method, was published by Leonhard Euler in 1768. After a group of multi-step methods was presented in 1883, Carl Runge, Karl Heun and Wilhelm Kutta developed significant improvements to Euler's method around 1900. These gave rise to the large group of Runge-Kutta methods, which form the most important class of one-step methods. Further developments in the 20th century include the idea of extrapolation and, above all, considerations on step width control, i.e. the selection of suitable lengths for the individual steps of a method. These concepts form the basis for solving difficult initial value problems, as they occur in modern applications, efficiently and with the required accuracy using computer programs.
Introduction
Ordinary differential equations
The development of differential and integral calculus by the English physicist and mathematician Isaac Newton and, independently of this, by the German polymath Gottfried Wilhelm Leibniz in the last third of the 17th century was a major impetus for the mathematization of science in the early modern period. These methods formed the starting point of the mathematical subfield of analysis and are of central importance in all natural and engineering sciences. While Leibniz was led to differential calculus by the geometric problem of determining tangents to given curves, Newton started from the question of how changes in a physical quantity can be determined at a specific point in time.
For example, when a body moves, its average speed is simply the distance traveled divided by the time required to travel it. However, in order to mathematically formulate the instantaneous velocity of the body at a certain point in time , a limit transition is necessary: Consider short time spans of length , the distances traveled and the corresponding average velocities .If the time period Δ 𝑡 is now allowed to converge towards zero and if the average velocities also approach a fixed value, then this value is called the (instantaneous) velocity at the given time . If denotes the position of the body at time 𝑡 , then write and call the derivative of .
The decisive step in the direction of differential equation models is now the reverse question: In the example of the moving body, let the velocity be known at every point in time 𝑡 and its position be determined from this. It is clear that the initial position of the body at a point in time 𝑡 0 must also be known in order to be able to solve this problem unambiguously. We are therefore looking for a function with that fulfills the initial condition with given values and .
In the example of determining the position 𝑥 of a body from its velocity, the derivative of the function being searched for is explicitly given. In most cases, however, the important general case of ordinary differential equations exists for a sought-after variable : Due to the laws of nature or the model assumptions, a functional relation is known that specifies how the deriativey of the function to be determined can be calculated from and from the (unknown) value . In addition, an initial condition must again be given, which can be obtained, for example, from a measurement of the required variable at a fixed point in time. To summarize, the following general type of task exists: Find the function that satisfies the equations
is fulfilled, where is a given function.
A simple example is a variable that grows exponentially. This means that the instantaneous change, i.e. the derivative , is proportional to itself. Therefore, with a growth rate and, for example, an initial condition . In this case, the required solution 𝑦 can already be found using elementary differential calculus and specified using the exponential function: .
The required function in a differential equation can be vector-valued, i.e. for each , can be a vector with components. This is also referred to as an -dimensional system of differential equations. In the case of a moving body, is its position in -dimensional Euclidean space and is its velocity at time . The differential equation therefore specifies the velocity of the trajectory with direction and magnitude at each point in time and space. The trajectory itself is to be calculated from this.
Basic idea of the one-step procedure
In the simple differential equation of exponential growth considered above as an example, the solution function could be specified directly. This is generally no longer possible for more complicated problems. Under certain additional conditions, it is then possible to show that a clearly determined solution to the initial value problem exists for the function ; however, this can then no longer be explicitly calculated using solution methods of analysis (such as separation of variables, an exponential approach or variation of the constants). In this case, numerical methods can be used to determine approximations for the solution sought.
The methods for the numerical solution of initial value problems of ordinary differential equations can be roughly divided into two large groups: the one-step and the multi-step methods. Both groups have in common that they calculate approximations for the desired function values at points step by step. The defining characteristic of one-step methods is that only the "current" approximation is used to determine the following approximation . In contrast, multi-step methods also include previously calculated approximations; a three-step method would therefore use and to determine the new approximation in addition to .
The simplest and most basic one-step method is the explicit Euler method, which was introduced by the Swiss mathematician and physicist Leonhard Euler in 1768 in his textbook Institutiones Calculi Integralis. The idea of this method is to approximate the solution sought by a piecewise linear function in which the gradient of the straight line piece is given by in each step from the point math>t_{j+1}</math> to the point . In more detail: The problem definition already gives a value of the function being searched for, namely . However, the derivative at this point is also known, as applies. This allows the tangent to the graph of the solution function to be determined and used as an approximation. At the point the following results with the step size
.
This procedure can now be continued in the following steps. Overall, this results in the following calculation rule for the explicit Euler method
with the increments .
The explicit Euler method is the starting point for numerous generalizations in which the gradient is replaced by gradients that approximate the behaviour of the solution between the points and more precisely. An additional idea for one-step methods is provided by the implicit Euler method, which uses as the gradient. At first glance, this choice does not seem very suitable, as is unknown. However, as a procedural step, we now obtain the equation
from which can be calculated (using a numerical method if necessary). If, for example, the arithmetic mean of the slopes of the explicit and implicit Euler method is selected as the slope, the implicit trapezoidal method is obtained. In turn, an explicit method can be obtained from this if, for example, the unknown on the right-hand side of the equation is approximated using the explicit Euler method, the so-called Heun method. All these methods and all other generalizations have the basic idea of one-step methods in common: the step
with a gradient that can depend on , and as well as (for implicit methods) on .
Definition
With the considerations from the introductory section of this article, the concept of the one-step method can be defined as follows: Let the solution of the initial value problem be sought
, .
It is assumed that the solution
exists on a given interval and is uniquely determined. Are
Intermediate positions in the interval and the corresponding increments, then this is given by
,
given method is a one-step method with method function . If does not depend on , then it is called an explicit one-step method. Otherwise, an equation for must be solved in each step and the method is called implicit.
Consistency and convergence
Convergence order
For a practical one-step procedure, the calculated should be good approximations for the values of the exact solution at the point . As the variables are generally -dimensional vectors, the quality of this approximation is measured using a vector norm as , the error at the point . It is desirable that these errors quickly converge to zero for all if the step sizes are allowed to converge to zero. In order to also capture the case of non-constant step sizes, is defined more precisely as the maximum of the step sizes used and the behavior of the maximum error at all points is considered in comparison to powers of . The one-step method for solving the given initial value problem is said to have the order of convergence if the estimate
applies to all sufficiently small with a constant that is independent of . The order of convergence is the most important parameter for comparing different one-step methods. A method with a higher order of convergence generally delivers a smaller total error for a given step size or, conversely, fewer steps are required to achieve a given accuracy. For a method with , it is to be expected that the error will only be approximately halved if the step size is halved. With a method of convergence order , on the other hand, it can be assumed that the error is reduced by a factor of approximately .
Global and local error
The errors considered in the definition of the convergence order are made up of two individual components in a way that initially seems complicated: On the one hand, of course, they depend on the error that the method makes in a single step by approximating the unknown gradient of the function being searched for by the method function. On the other hand, however, it must also be taken into account that the starting point of a step generally does not match the exact starting point ; the error after this step therefore also depends on all errors that have already been made in the previous steps. Due to the uniform definition of the one-step procedures, which differ only in the choice of the procedure function , it can be proven, however, that (under certain technical conditions at ) one can directly infer the order of convergence from the error order in a single step, the so-called consistency order.
The concept of consistency is a general and central concept of modern numerical mathematics. While the convergence of a method involves investigating how well the numerical approximations match the exact solution, in simplified terms the "reverse" question is asked in the case of consistency: How well does the exact solution fulfill the method specification? In this general theory, a method is convergent if it is consistent and stable. To simplify the notation, the following consideration assumes that an explicit one-step procedure
with a constant step size exists. With the true solution , the local truncation error (also called local process error) is defined as
.
Thus, one assumes that the exact solution is known, starts a method step at the point and forms the difference to the exact solution at the point . This defines: A one-step method has the consistency order if the estimate
applies to all sufficiently small with a constant that is independent of .
The striking difference between the definitions of the consistency order and the convergence order is the power instead of . This can be clearly interpreted as meaning that a power of the step size is "lost" during the transition from local to global error. The following theorem, which is central to the theory of one-step methods, applies:
If the process function is Lipschitz-continuous and the associated one-step process has the consistency order , then it also has the convergence order .
The Lipschitz continuity of the process function as an additional requirement for stability is generally always fulfilled if the function from the differential equation itself is Lipschitz-continuous. This requirement must be assumed for most applications anyway in order to guarantee the unambiguous solvability of the initial value problem. According to the theorem, it is therefore sufficient to determine the consistency order of a one-step method. In principle, this can be achieved by Taylor expansion of to powers of . In practice, the resulting formulas for higher orders become very complicated and confusing, so that additional concepts and notations are required.
Stiffness and A-stability
The convergence order of a method is an asymptotic statement that describes the behavior of the approximations when the step size converges to zero. However, it says nothing about whether the method actually calculates a useful approximation for a given fixed step size. Charles Francis Curtiss and Joseph O. Hirschfelder first described in 1952 that this can actually be a major problem for certain types of initial value problems. They had observed that the solutions to some differential equation systems in chemical reaction kinetics could not be calculated using explicit numerical methods and called such initial value problems "stiff". There are numerous mathematical criteria for determining how stiff a given problem is. Stiff initial value problems are usually systems of differential equations in which some components become constant very quickly while other components change only slowly. Such behavior typically occurs in the modeling of chemical reactions. However, the most useful definition of stiffness for practical applications is: An initial value problem is stiff if, when solving it with explicit one-step methods, the step size would have to be chosen "too small" in order to obtain a useful solution. Such problems can therefore only be solved using implicit methods.
This effect can be illustrated more precisely by examining how the individual methods cope with exponential decay. According to the Swedish mathematician Germund Dahlquist, the test equation
with the exponentially decreasing solution for . The adjacent diagram shows - as an example for the explicit and implicit Euler method - the typical behavior of these two groups of methods for this seemingly simple initial value problem: If too large a step size is used in an explicit method, this results in strongly oscillating values that build up over the course of the calculation and move further and further away from the exact solution. Implicit methods, on the other hand, typically calculate the solution for arbitrary step sizes qualitatively correctly, namely as an exponentially decreasing sequence of approximate values.
More generally, the above test equation is also considered for complex values of . In this case, the solutions are oscillations whose amplitude remains limited precisely when , i.e. the real part of is less than or equal to 0. This makes it possible to formulate a desirable property of one-step methods that are to be used for stiff initial value problems: the so-called A-stability. A method is called A-stable if it calculates a sequence of approximations for any step size applied to the test equation for all with , which remains bounded (like the true solution). The implicit Euler method and the implicit trapezoidal method are the simplest examples of A-stable one-step methods. On the other hand, it can be shown that an explicit method can never be A-stable.
Special procedures and procedure classes
Simple procedures of order 1 and 2
As the French mathematician Augustin-Louis Cauchy proved around 1820, the Euler method has a convergence order of 1. If you average the slopes of the explicit Euler method and of the implicit Euler method, as they exist at the two end points of a step, you can hope to obtain a better approximation over the entire interval. In fact, it can be proven that the implicit trapezoidal method obtained in this way
has a convergence order of 2. This method has very good stability properties, but is implicit, meaning that an equation for 𝑦 𝑗 + 1 must be solved in each step. If this variable is approximated on the right-hand side of the equation using the explicit Euler method, the result is the explicit method of Heun
,
which also has convergence order 2. Another simple explicit method of order 2, the improved Euler method, is obtained by the following consideration: A "mean" slope in the method step would be the slope of the solution 𝑦 in the middle of the step, i.e. at the point . However, as the solution is unknown, it is approximated by an explicit Euler step with half the step size. This results in the following procedure
.
These one-step methods of order 2 were all published as improvements of the Euler method in 1895 by the German mathematician Carl Runge.
Runge-Kutta method
The aforementioned ideas for simple one-step methods lead to the important class of Runge-Kutta methods when generalized further. For example, Heun's method can be presented more clearly as follows: First, an auxiliary slope is calculated, namely the slope of the explicit Euler method. This is used to determine a further auxiliary slope, here . The actual process gradient used is then calculated as a weighted average of the auxiliary gradients, i.e. in Heun's method. This procedure can be generalized to more than two auxiliary slopes. An - -stage Runge-Kutta method first calculates auxiliary slopes by evaluating 𝑓 at suitable points and then as a weighted average. In an explicit Runge-Kutta method, the auxiliary slopes are calculated directly one after the other; in an implicit method, they are obtained as solutions to a system of equations. A typical example is the explicit classical Runge-Kutta method of order 4, which is sometimes simply referred to as the Runge-Kutta method: First, the four auxiliary slopes
and then the weighted average is calculated as the process slope
is used. This well-known method was published by the German mathematician Wilhelm Kutta in 1901, after Karl Heun had found a three-step one-step method of order 3 a year earlier.
The construction of explicit methods of even higher order with the smallest possible number of steps is a mathematically quite demanding problem. As John C. Butcher was able to show in 1965, there are, for example, only a minimum of six steps for order 5; an explicit Runge-Kutta method of order 8 requires at least 11 steps. In 1978, the Austrian mathematician Ernst Hairer found a method of order 10 with 17 levels. The coefficients for such a method must fulfill 1205 determinant equations. With implicit Runge-Kutta methods, the situation is simpler and clearer: for every number of steps there is a method of order ; this is also the maximum achievable order.
Extrapolation method
The idea of extrapolation is not limited to the solution of initial value problems with one-step methods, but can be applied analogously to all numerical methods that discretize the problem to be solved with a step size . A well-known example of an extrapolation method is the Romberg integration for the numerical calculation of integrals. In general, let be a value that is to be determined numerically, in the case of this article, for example, the value of the solution function of an initial value problem at a given point. A numerical method, for example a one-step method, calculates an approximate value for this, which depends on the choice of step size . It is assumed that the method is convergent, i.e. that converges to when converges to zero. However, this convergence is only a purely theoretical statement, as approximate values can be calculated for a finite number of different step sizes , but of course the step size cannot be allowed to "converge to zero". However, the calculated approximations for different step sizes can be interpreted as information about the (unknown) function : In the extrapolation methods, is approximated by an interpolation polynomial, i.e. by a polynomial with
for . The value of the polynomial at the point is then used as a computable approximation for the non-computable limit value of for towards zero. An early successful extrapolation algorithm for initial value problems was published by Roland Bulirsch and Josef Stoer in 1966.
A concrete example in the case of a one-step method of order can illustrate the general procedure of extrapolation. With such a method, the calculated approximation for small step sizes ℎ can be easily described by a polynomial of the form
with initially unknown parameters and . If you now calculate two approximations and using the method for a step size and for half the step size , two linear equations for the unknowns and are obtained from the interpolation conditions and .
The value extrapolated to
is then generally a significantly better approximation than the two values calculated initially. It can be shown that the order of the one-step method obtained in this way is at least , i.e. at least 1 greater than the original method.
Method with step width control
One advantage of the one-step method is that any step size can be used in each step 𝑗 independently of the other steps. In practice, this obviously raises the question of how ℎ 𝑗 should be selected. In real applications, there will always be an error tolerance with which the solution of an initial value problem is to be calculated; for example, it would be pointless to determine a numerical approximation that is significantly more "accurate" than the data for initial values and parameters of the given problem, which are subject to measurement errors. The aim will therefore be to select the step sizes in such a way that, on the one hand, the specified error tolerances are adhered to and, on the other hand, as few steps as possible are used in order to keep the computational effort to a minimum. This problem, in which an ordinary differential equation is given together with an initial condition, plays a central role in all natural and engineering sciences and is also becoming increasingly important in the economic and social sciences, for example. Initial value problems are used to analyze, simulate or predict dynamic processes.
For well-conditioned initial value problems, it can be shown that the global process error is approximately equal to the sum of the local truncation errors in the individual steps. Therefore, the largest possible should be selected as the step size, for which is below a selected tolerance threshold. The problem here is that cannot be calculated directly, as it depends on the unknown exact solution of the initial value problem at the point . The basic idea of step size control is therefore to approximate with a method that is more accurate than the underlying basic method.
Two basic ideas for step width control are step width halving and embedded processes. With step size halving, the result for two steps with half the step size is calculated as a comparison value in addition to the actual process step. A more precise approximation for is then determined from both values by extrapolation and the local error 𝜂 𝑗 is estimated. If this is too large, this step is discarded and repeated with a smaller step size. If it is significantly smaller than the specified tolerance, the step size can be increased in the next step. The additional computational effort for this step width halving procedure is relatively high; this is why modern implementations usually use so-called embedded procedures for step width control. The basic idea is to calculate two approximations for in each step using two one-step methods that have different orders of convergence and thus estimate the local error. In order to optimize the computational effort, the two methods should have as many computational steps in common as possible: They should be "embedded in each other". Embedded Runge-Kutta methods, for example, use the same auxiliary slopes and differ only in how they average them. Well-known embedded methods include the Runge-Kutta-Fehlberg method (, 1969) and the Dormand-Prince method (J. R. Dormand and P. J. Prince, 1980).
Practical example: Solving initial value problems with numerical software
Numerous software implementations have been developed for the mathematical concepts outlined in this article, which allow the user to solve practical problems numerically in a simple way. As a concrete example, a solution to the Lotka-Volterra equations will now be calculated using the popular numerical software Matlab. The Lotka-Volterra equations are a simple model from biology that describes the interactions between predator and prey populations. Given the differential equation system
with the parameters and the initial condition , . Here, and correspond to the temporal development of the prey and predator population respectively. The solution should be calculated on the time interval .
For the calculation using Matlab, the function is first defined for the given parameter values on the right-hand side of the differential equation :
a = 1; b = 2; c = 1; d = 1;
f = @(t,y) [a*y(1) - b*y(1)*y(2); c*y(1)*y(2) - d*y(2)];
The time interval and the initial values are also required:
t_int = [0, 20];
y0 = [3; 1];
The solution can then be calculated:
[t, y] = ode45(f, t_int, y0);
The Matlab function ode45 implements a one-step method that uses two embedded explicit Runge-Kutta methods with convergence orders 4 and 5 for step size control.
The solution can now be plotted, as a blue curve and as a red curve; the calculated points are marked by small circles:figure(1)
plot(t, y(:,1), 'b-o', t, y(:,2), 'r-o')
The result is shown below in the left-hand image. The right-hand image shows the step sizes used by the method and was generated with
figure(2)
plot(t(1:end-1), diff(t))This example can also be executed without changes using the free numerical software GNU Octave. However, the method implemented there results in a slightly different step size sequence.
Literature
External links
References
Computational mathematics
Differential equations | One-step method | [
"Mathematics"
] | 5,440 | [
"Applied mathematics",
"Mathematical objects",
"Computational mathematics",
"Differential equations",
"Equations"
] |
77,306,203 | https://en.wikipedia.org/wiki/Richard%20G.%20Luthy | Richard G. Luthy (born 1945) is the Silas H. Palmer Professor of Civil and Environmental Engineering at Stanford University, California. His specialty is water quality engineering and the future of urban water supplies and reuse in water-stressed regions.
Luthy was elected to the National Academy of Engineering in 1999 for leadership in water quality protection and engineering.
Career
During his childhood, Luthy lived in Prairie Village, KS and attended Prairie Elementary School. His family moved west to Palo Alto, CA in 1956 when he was in sixth grade. He attended the University of California, Berkeley from 1963-1967, majoring in chemical engineering. He received an MS from the University of Hawaiʻi at Mānoa in 1969 in its newly-formed program in ocean engineering.
Luthy served in the US Navy Civil Engineer Corps from 1969-1972 and was promoted from Ensign to Lieutenant. He was a qualified Navy deep sea diving and salvage officer with the Seabees with tours of duty at Port Hueneme, CA in the Naval Facilities Engineering Service Center, and at Davisville, Rhode Island where he was assistant office in charge of Underwater Construction Team One. Luthy was a deep submergence vehicle operator for the Naval Experimental Manned Observatory (DSV-5 Nemo). This was the first submersible with a transparent, all-acrylic spherical hull designed to oversee underwater construction and salvage work.
Luthy returned to the University of California, Berkeley on GI Bill for graduate studies in environmental engineering on water treatment and water quality.
Academic research
Luthy joined the faculty in civil and environmental engineering at Carnegie Mellon University in 1975. He served as Associate Dean in the university's school of engineering, and as Department Head of Civil and Environmental Engineering. He was recruited by Stanford and returned to Palo Alto in 1999. He was chair of Stanford's Civil and Environmental Engineering Department from 2003-2009.
Luthy's research has emphasized physicochemical processes for water quality engineering. His graduate studies and early research coincided with the passage of nation's major water quality legislation, as well as with the energy crisis in the 1970s. This resulted in research projects supported by the United States Environmental Protection Agency, the Energy Research and Development Administration and its successor, United States Department of Energy, with studies on water management and treatment in coal gasification and liquefaction. That work led to a body of research on the behavior of polycyclic aromatic hydrocarbons in treatment and fate in the environment. Research in the 1980s and 1990s addressed soil and groundwater contamination and bioavailability of hydrophobic organic compounds and PFCs, so-called forever chemicals, for protection of groundwater. His research focused on persistent and bioaccumulative organic compounds in sediments that resulted in the development of in-situ treatment technologies to sequester toxic hydrophobic organic compounds.
Having seen California grow in population and prosper economically, he witnessed how the state's major water infrastructure that served the state well in mid-20th Century was stretched to its limits to meet the needs of the 21st Century. Luthy worked with colleagues at Stanford and elsewhere on more sustainable urban water systems including reuse and stormwater capture for water supply. From 2011 to 2022 he was the Director of the National Science Foundation Engineering Research Center for Re-inventing the Nation's Urban Water Infrastructure.
Luthy is recognized for advancement of environmental engineering with energy-efficient, decentralized water reuse; urban stormwater capture and treatment for water supply; and urban water supply strategies for California in the face of maintaining environmental flows in rivers while addressing climate change and competing demands.
Educational contributions and achievements
Luthy is acknowledged for significant contributions to environmental engineering education, research, and practice.
Luthy has served on numerous academic advisory boards and visiting committees, as well as committees of the NSF, EPA, NRC, NAE and other organizations. He is a past member and chair of the National Research Council's Water Science and Technology Board. Luthy has held various positions in the Association of Environmental Engineering and Science Professors including Vice President and President, and a founding board member and subsequent Chair of the AEESP Foundation. He has served on and chaired the NAE Peer Committee for Civil and Environmental Engineering.
Selected publications
Luthy, R. G., Selleck, R. E., & Galloway, T. R. (1977). Surface properties of petroleum refinery waste oil emulsions. Environmental Science & Technology, 11(13), 1211-1217.
Luthy, R. G., Selleck, R. E., & Galloway, T. R. (1978). Removal of emulsified oil with organic coagulants and dissolved air flotation. Journal (Water Pollution Control Federation), 331-346.
Luthy, R. G. (1981). Treatment of coal coking and coal gasification wastewaters. Journal (Water Pollution Control Federation), 325-339.
Edwards, D. A., Liu, Z., & Luthy, R. G. (1994). Experimental data and modeling for surfactant micelles, HOCs, and soil. Journal of Environmental Engineering, 120, 23-41.
Ahn, S., Werner, D., Karapanagioti, H. K., McGlothlin, D. R., Zare, R. N., & Luthy, R. G. (2005). Phenanthrene and Pyrene Sorption and Intraparticle Diffusion in Polyoxymethylene, Coke, and Activated Carbon. Environmental Science & Technology, 17(39), 6516-6526.
Ghosh, U., Zimmerman, J. R., & Luthy, R. G. (2003). PCB and PAH speciation among particle types in contaminated harbor sediments and effects on PAH bioavailability. Environmental Science and Technology, 37.
Luthy, R. G., Aiken, G. R., Brusseau, M. L., Cunningham, S. D., Gschwend, P. M., Pignatello, J. J., ... & Westall, J. C. (1997). Sequestration of hydrophobic organic contaminants by geosorbents. Environmental Science & Technology, 31(12), 3341-3347.
Higgins, C. P., & Luthy, R. G. (2006). Sorption of perfluorinated surfactants on sediments. Environmental science & technology, 40(23), 7251-7256.
Patmont, C. R., Ghosh, U., LaRosa, P., Menzie, C. A., Luthy, R. G., Greenberg, M. S., ... & Quadrini, J. (2015). In situ sediment treatment using activated carbon: a demonstrated sediment cleanup technology. Integrated environmental assessment and management, 11(2), 195-207.
Luthy, R. G., Wolfand, J. M., & Bradshaw, J. L. (2020). Urban water revolution: Sustainable water futures for California cities. Journal of Environmental Engineering, 146(7), 04020065.
Luthy, R. G., & Sedlak, D. L. (2015). Urban water-supply reinvention. Daedalus, 144(3), 72-82.
Gile, B. C., Sciuto, P. A., Ashoori, N., & Luthy, R. G. (2020). Integrated Water Management at the Peri-Urban Interface: A Case Study of Monterey, California. Water (20734441), 12(12)
Bischel, H. N., Simon, G. L., Frisby, T. M., & Luthy, R. G. (2012). Management experiences and trends for water reuse implementation in Northern California. Environmental science & technology, 46(1), 180-188.
Luthy, R. G., Sharvelle, S., & Dillon, P. (2019). Urban stormwater to enhance water supply. Environmental Science & Technology, 53(10), 5534-5542.
Galdi, S. M., Szczuka, A., Shin, C., Mitch, W. A., & Luthy, R. G. (2022). Dissolved methane recovery and trace contaminant fate following mainstream anaerobic treatment of municipal wastewater. ACS Es&t Engineering, 3(1), 121-130.
Pritchard, J. C., Cho, Y. M., Hawkins, K. M., Spahr, S., Higgins, C. P., & Luthy, R. G. (2023). Predicting PFAS and Hydrophilic Trace Organic Contaminant Transport in Black Carbon-Amended Engineered Media Filters for Improved Stormwater Runoff Treatment. Environmental Science & Technology, 57(38), 14417-14428.
Spahr, S., Teixidó, M., Gall, S. S., Pritchard, J. C., Hagemann, N., Helmreich, B., & Luthy, R. G. (2022). Performance of biochars for the elimination of trace organic contaminants and metals from urban stormwater. Environmental Science: Water Research & Technology, 8(6), 1287-1299.
Gile, B. C., Sherris, A. R., Holmes, R. T., Fendorf, S., & Luthy, R. G. Water Supply Planning in the Face of Drought and Ecosystem Flows: Examining the Impact of the Bay-Delta Plan on Bay Area Water Supply. Environmental science & technology.
References
1945 births
Living people
Environmental engineers | Richard G. Luthy | [
"Chemistry",
"Engineering"
] | 2,069 | [
"Environmental engineers",
"Environmental engineering"
] |
68,471,775 | https://en.wikipedia.org/wiki/HD%2032515 | HD 32515 (HR 1635) is a solitary star located in the southern constellation Caelum. It has an apparent magnitude of 5.9, making it faintly visible to the naked eye under ideal conditions. The star is situated at a distance of 326 light years but is recceding with a heliocentric radial velocity of .
HD 32515 has a stellar classification of K2 III, indicating that it is an early K-type giant star. HD 32515 has an angular diameter of (after limb darkening correction); this yields a diameter 11.9 times that of the Sun at its estimated distance. At present, it has 152% of the Sun's mass and shines at 56.3 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 4,540 K, giving it an orange glow. HD 32515 has a similar metallicity and age to the Sun and spins slowly with a projected rotational velocity of
References
Caelum
K-type giants
Durchmusterung objects
1635
032515
Caeli, 26
023446 | HD 32515 | [
"Astronomy"
] | 222 | [
"Caelum",
"Constellations"
] |
68,473,340 | https://en.wikipedia.org/wiki/Azurmalachite | Azurmalachite is a mixture of azurite and malachite. It is alternatively called azuromalachite, azurite-malachite and malachite-azurite.
Azurmalachite has a distinctive mottled green and blue coloration. It is relatively rare but can sometimes be found above copper deposits. The main sources for mined azurmalachite are the United States, France, and Namibia.
References
Copper ores
Gemstones | Azurmalachite | [
"Physics"
] | 100 | [
"Materials",
"Gemstones",
"Matter"
] |
68,474,287 | https://en.wikipedia.org/wiki/Chinese%20elephants%20expedition | In March 2020, a group of 14 Asian elephants left their habitat in Pu'er City in the southeastern province of Yunnan, China. The elephants were reported as far south as Menghai County, Xishuangbanna Dai Autonomous Prefecture. After 17 months, they returned to their original sanctuary after a journey of 1300 km in early August 2021. These elephants were the center of attention of the Chinese people and worldwide.
Safety measures
Chinese authorities also set up an emergency committee to ensure the elephants return home safely. For the safe return, the committee has built temporary roads for the elephants, electric fences have been installed, and traps have been set up at various places to keep them on track. They also deployed more than 25,000 police officers to provide food for the 14 elephants and to ensure the safety of residents in their paths, and more than 1,500 vehicles were also earmarked. A force of 360 people in 76 vehicles and nine drones monitored the elephants.
David Attenborough covered the herd migration in Netflix's 2023 documentary Our Planet II, providing visual documentation and education of the migration and the effort to keep them safe.
References
2021 in China
Animal migration
Elephants
Nature conservation in China
Natural history of Yunnan
Elephant conservation | Chinese elephants expedition | [
"Biology"
] | 247 | [
"Ethology",
"Behavior",
"Animal migration"
] |
68,474,360 | https://en.wikipedia.org/wiki/Global%20Action%20Fund%20for%20Fungal%20Infections | The Global Action For Fungal Infections (GAFFI), is an international foundation focussed on raising awareness of and collecting worldwide data on fungal disease. Its aim is to make reliable and inexpensive diagnostic tests widely available.
In 2015, GAFFI proposed action to make affordable fungal diagnostic tests and antifungal treatments available to 95% of the world's population by 2025. In 2018 GAFFI calculated that globally around one billion people have fungal infections of the skin, more than one million people become blind from fungal keratitis, more than 10 million people develop lung disease after breathing in fungal spores, and more than 300 million people have a severe fungal infection every year, of whom over 1.5 million die.
Location and members
The GAFFI is based in Switzerland and the United Kingdom. Its Board Chair is Oddi Aasheim .
Aims
GAFFI is an international foundation focussed on raising awareness of and collecting worldwide data on fungal disease burden . Its primary aims are to get reliable and inexpensive diagnostic tests to be widely available, particularly in low and middle income countries. The tests can be produced but the increasing cost of regulatory approval causes difficulty in getting them from the experimental stage in the laboratory to real world use in clinics.
Activities
GAFFI has successfully advocated for multiple diagnostics as Essential to be listed on the World Health Organization's EDL . GAFFI tracks country registration and access to Essential Medicines for antifungal agents .
GAFFI also estimates and publicises data on fungal diseases incidence and prevalence (burden).
The GAFFI was launched in London in 2013 . In 2015, GAFFI proposed action to make fungal diagnostic tests and antifungal treatments available to 95% of the world's population by 2025 95/95 by 2025 . Six actions were proposed:
Provide rapid diagnostic tests that do not rely on culture, and that are affordable.
Establish at least one laboratory in each country, led by fungal disease experts
Create clinical guidelines and teaching programmes
Better distribution of antifungal medicines on the WHO Model List of Essential Medicines
Establish fungal infection surveillance systems
Invest in public health mycology
In 2018 the GAFFI calculated that globally around one billion people every year have fungal infections of the skin, more than one million people become blind from fungal keratitis, more than 10 million people develop lung disease after breathing in fungal spores, and more than 300 million people have severe fungal infections, of which over 1.5 million will die from it.
In 2022, GAFFI published a report on access to diagnostics in 49 African countries, with the Africa Centre for Disease Control and Prevention. Many gaps remain.
References
Medical and health organizations
Fungal diseases
Organisations based in Switzerland
Organisations based in the United Kingdom | Global Action Fund for Fungal Infections | [
"Biology"
] | 544 | [
"Fungi",
"Fungal diseases"
] |
68,474,912 | https://en.wikipedia.org/wiki/Hale%27s%20law | In solar physics, Hale's law, also known as Hale's polarity law or the Hale–Nicholson law, is an empirical law for the orientation of magnetic fields in solar active regions.
It applies to simple active regions that have bipolar magnetic field configurations where one magnetic polarity is leading with respect to the direction of solar rotation. Hale's law states that, in the same northern or southern solar hemisphere, such active regions have the same leading magnetic polarity; that, in opposite hemispheres, such active regions have the opposite leading polarity; and that, from one sunspot cycle to the next, these polarities reverse. It is named after George Ellery Hale and Seth Barnes Nicholson, whose observations of active-region magnetic fields led to the law's formulation in the early 20th century.
Hale's law, along with Joy's law and Spörer's law, provides observational constraints for models of the solar dynamo, which generates the Sun's magnetic field. Hale's law suggests that active regions originate from a highly organized toroidal magnetic field in the Sun's interior that reverses polarity across the equator and alternates polarity between sunspot cycles.
History
The solar magnetic field was first detected in 1908 by George Ellery Hale, when he showed observationally that sunspots had strong, bipolar magnetic fields. With these observations, Hale also noted that the majority of sunspot groups within the same northern or southern solar hemisphere shared the same leading polarity and that this pattern reversed across the equator. As solar cycle 14 transitioned into solar cycle 15, further observations were carried out by Hale and his collaborators. In 1919, their work revealed that the magnetic polarity of sunspot pairs within both hemispheres reversed from one 11-year sunspot cycle to the next. These patterns became collectively known as Hale's polarity law, or simply Hale's law.
Definition
Hale's law describes the magnetic polarity associated with solar active regions. The magnetic field of most active regions can be approximated by a pair of magnetic monopoles of opposing polarity, in which case the region is referred to as a bipolar active region. These poles are generally oriented so that one pole is leading with respect to the direction of solar rotation and the other is trailing.
Hale's law states that bipolar active regions have the following properties depending on whether the region is located in the northern or southern solar hemisphere:
In the same hemisphere, regions tend to have the same leading polarity.
In the opposite hemisphere, regions tend to have the opposite leading polarity.
Leading polarities in both hemispheres reverse from one sunspot cycle to the next.
Anti-Hale regions
Bipolar active regions that violate Hale's law are known as anti-Hale regions. Estimates of the percentage of bipolar active regions that violate Hale's law have ranged from 2 to 9%. Small, weak, ephemeral active regions violate Hale's law more frequently than average with a relative number around 40%. In contrast, only 4% of medium to large sized active regions violate Hale's law. Furthermore, anti-Hale regions—and small regions in general—tend to have an orientation angle, or tilt, that does not follow Joy's law and have been found to be more prevalent during solar minima.
Hale cycle
Since Hale's law states that the leading magnetic polarities in each hemisphere alternate between sunspot cycles, it takes two full cycles for the leading polarities to return to their original pattern. This indicates that the approximately 11-year sunspot cycle is one-half of a 22-year magnetic cycle, which is sometimes referred to as a Hale cycle.
Solar dynamo
Hale's law has important implications for the Sun's internal magnetic field and the dynamo that drives it. Namely, the observation that active regions in a given north-south hemisphere all have the same leading magnetic polarity suggests that their emergence is the manifestation of a highly organized east-west-aligned, or toroidal, magnetic field in the Sun's interior. Additionally, the observations that the polarity of the leading magnetic field reverses across the equator and alternates between successive sunspot cycles further suggests that such a toroidal field also reverses polarity across the equator and alternates polarities between cycles.
Hale's law, along with Joy's law for the tilt of sunspot groups and Spörer's law for the variation of active region latitudes, provides strong observational constraints for models of the solar dynamo. For example, according to the Babcock–Leighton mechanism for the solar dynamo, the toroidal field implied by Hale's law is the result of the latitudinal solar differential rotation winding up a north-south-aligned, or poloidal, magnetic field.
See also
Gnevyshev–Ohl rule
List of solar cycles
References
Solar phenomena
Solar cycles | Hale's law | [
"Physics"
] | 994 | [
"Physical phenomena",
"Stellar phenomena",
"Solar phenomena"
] |
78,701,485 | https://en.wikipedia.org/wiki/Dina%20Triyoso | Dina H. Triyoso is an American materials scientist, and an expert on high-κ dielectrics and their applications in semiconductor-based electronics, and more generally on materials and processes for electronic devices. She works for Tokyo Electron (TEL), in New York.
Triyoso was a student of chemical engineering at Texas A&M University, where she received her Ph.D. in 2000, advised by Cellular engineer Theresa Good. She worked for Motorola Semiconductor Products and its spin-off Freescale Semiconductor, and then for GlobalFoundries, before taking her present position at Tokyo Electron in 2019.
She was named to the 2025 class of IEEE Fellows "for contributions to high-k metal gate complementary metal-oxide-semiconductor technology".
References
External links
Year of birth missing (living people)
Living people
American materials scientists
Women materials scientists and engineers
Texas A&M University alumni
Fellows of the IEEE | Dina Triyoso | [
"Materials_science",
"Technology"
] | 187 | [
"Women materials scientists and engineers",
"Materials scientists and engineers",
"Women in science and technology"
] |
78,702,263 | https://en.wikipedia.org/wiki/Ammonium%20tellurate | Ammonium tellurate is a chemical compound with the chemical formula .
Synthesis
The compound can be obtained by oxidation of tellurium dioxide with hydrogen peroxide in an ammonia medium.
Physical properties
Ammonium tellurate forms white crystals, soluble in water.
Chemical properties
Whrn heated, the compound decomposes releasing toxic fumes of , NOx, and .
References
Ammonium compounds
Tellurates
Tellurium(IV) compounds | Ammonium tellurate | [
"Chemistry"
] | 90 | [
"Ammonium compounds",
"Salts"
] |
78,702,277 | https://en.wikipedia.org/wiki/HD%2073752 | HD 73752 is a multiple star system located in the southern constellation of Pyxis. With an apparent magnitude of 5.17, it can be faintly seen by the naked eye from Earth as a yellow-hued dot of light. As such, it is listed in the Bright Star Catalogue as HR 3430. It is located at a distance of approximately according to Gaia EDR3 parallax measurements, and is receding at a heliocentric radial velocity of 52.13 km/s.
Physical properties
The system is roughly seven billion years old, much older than the Solar System (), and belongs to the thin disk population of the Milky Way.
The primary star, HD 73752 Aa, is an aging subgiant, a star that has fused all the hydrogen in its core into helium and evolved past the main sequence, with the spectral type G5IV. It is 21% more massive than the Sun, equivalent to a typical F-type main-sequence star with the spectral type F7V, but has expanded to a radius of 1.68 . It radiates 2.31 times the luminosity of the Sun from its photosphere at an effective temperature of . The entire system is very metal-rich with a metallicity of +0.32, which equates to an iron abundance 100.32 ≈ 2.1 times that of the Sun. A low-mass close companion, Ab, orbits Aa in a orbit, but its precise parameters remain uncertain.
The secondary star, which is in a 127-year binary orbit with the Aa/Ab pair, is a G-type or K-type main-sequence star similar to the Sun in mass and radius, but substantially cooler at . As such, it emits only three-fifths the Sun's luminosity.
Multiplicity
HD 73752 has been known to be a close visual binary since 1874. As early as 1943, a third unseen component was suspected, though this suggestion of a ~0.1 object in a 35-year orbit remained inconclusive, and a 1967 study turned up little evidence. Radial velocity variations were observed in 1980 and 2006 that strongly implied a low-mass object, though the orbital parameters could not be obtained. In 2016, HD 73752 A was finally confirmed to be a spectroscopic binary.
Additionally, another possible companion, 13.7 magnitudes fainter than the primary in the H band, was noticed at a separation of 4".50 in right ascension and 6".02 in declination, but this has not been followed up on.
Circumstellar disc
HD 73752 has been referred to as a "Vega-like star," a star that exhibits excess infrared emission due to an optically thin dusty circumstellar disc containing almost no gas. Because this star is past the main sequence, the process in which the emissions are produced may diverge from that of younger such stars e.g., Epsilon Eridani, HD 53143, HD 69830, and HD 98800. In 2012, a debris disc was detected at a distance of 21 AU from the primary, an unstable position close to the secondary star's orbit at 34 AU. Despite this, a 2019 study did not find any significant infrared excess at a wavelength of .
See also
70 Virginis: a G-type subgiant similar to HD 73752 Aa.
List of star systems within 60–65 light-years
Notes
References
G-type subgiants
G-type main-sequence stars
K-type main-sequence stars
Triple star systems
Pyxis
073752
BD-22 02345
J08390794-2239427
042430
3430 | HD 73752 | [
"Astronomy"
] | 768 | [
"Pyxis",
"Constellations"
] |
78,702,573 | https://en.wikipedia.org/wiki/Mizo%20calendar | The Mizo calendar is a traditional lunisolar calendar utilized by the Mizo people of northeast India.
This calendar comprises 12 months, each closely associated with the cultural, agricultural, and spiritual practices of the Mizo people.
Traditionally, the Mizo people observed the moon's phases. They counted approximately 14 days from the moon's first appearance in the sky to its full moon phase. Similarly, they believed it took another 14 days for the moon to fade completely after the full moon stage. The 15th night, when the moon neither fully waxed nor waned, was considered unique and not part of either phase. Based on these calculations, each lunar month was determined to be 29 days long.
Months
Summer solstice
The Mizo people identified the 21st day of the Nikir month as the longest day of the year, known in modern terms as the summer solstice. They referred to this day as Lalmanga Nu Lawmrawih Ni—a name rooted in an enduring local folktale. The term Nikir translates to "returning of the sun."
According to tradition, a widow called Lalmanga Nu (lit. 'mother of Lalmanga') recognised the significance of this day and annually encouraged her friends to work in her jhum fields on the 21st day of Nikir to maximize labour input during the longest day. After Lalmanga Nu Lawmrawih Ni, the Mizo believed that the sun began its "return," causing days to grow progressively shorter.
Key dates
Chapchar Kut – first Friday of Vau thla.
References
Calendar
Ancient calendars
Lunar calendars
Lunisolar calendars
Time in India | Mizo calendar | [
"Physics"
] | 340 | [
"Spacetime",
"Calendars",
"Physical quantities",
"Time"
] |
78,703,246 | https://en.wikipedia.org/wiki/Ammonium%20tetrathiovanadate | Ammonium tetrathiovanadate is a chemical compound with the chemical formula .
Physical properties
Ammonium tetrathiovanadate forms violet crystals of orthorhombic symmetry.
Chemical properties
Like other ammonium salts, ammonium tetrathiovanadate decomposes when heated:
References
Ammonium compounds
Vanadates
Vanadium(V) compounds | Ammonium tetrathiovanadate | [
"Chemistry"
] | 75 | [
"Ammonium compounds",
"Salts"
] |
78,703,534 | https://en.wikipedia.org/wiki/Changchengia | Changchengia is a genus of possible alga from the early-mid Proterozoic. It contains one species, Changchengia stipitata. This genus is known from various formations, such as the Olive Shales of the Vindhya Range and the Saraipali Formation in India, alongside the Chuanlinggou Formation of China.
Description
Changchengia is between long and between wide, with a thin blade-like thallus. In C. stipitata the thallus is usually ribbon-shaped or lanceolate with folded and lamellose margins, with the widest point in the middle and tapering towards the base and tip. However, fossils from the Chuanlinggou Formation are more ovoid or obcordate in shape, alongside tapering holdfasts. The base is obtuse and contacts with a long and linear parastem, which itself connects to a holdfast. This genus shares many morphological similarities with Tuanshanzia, and infact it was classified within this genus at first. However, a conspicuous difference between the two is that Tuanshanzia has no parastem, and instead its thallus slowly narrows towards the holdfast.
References
Enigmatic eukaryote taxa
Paleoproterozoic
Mesoproterozoic
Fossil taxa described in 1997 | Changchengia | [
"Biology"
] | 275 | [
"Eukaryotes",
"Eukaryote stubs"
] |
78,703,792 | https://en.wikipedia.org/wiki/Amidantel | Amidantel is a pharmaceutical drug used in veterinary medicine. It is an anthelmintic active against nematodes, filaria, and cestodes.
References
Veterinary drugs
Anthelmintics
Amidines | Amidantel | [
"Chemistry"
] | 45 | [
"Bases (chemistry)",
"Amidines",
"Functional groups"
] |
78,704,062 | https://en.wikipedia.org/wiki/Lichenopeltella%20lobariae | Lichenopeltella lobariae is a species of lichenicolous (lichen-dwelling) fungus in the family Microthyriaceae. It grows exclusively on foliose lichen species, including Lobaria pulmonaria and Nephroma arcticum.
Taxonomy
The species was first discovered during studies of fungi growing on lichens in the western Pyrenees mountains of France and Spain. It was formally described as a new species in 1996 by the mycologists Javier Etayo and Paul Diederich. The type specimen (holotype) was collected near Aspe peak in France at an elevation of 1,350 metres in a mixed beech-fir forest.
Description
Lichenopeltella lobariae produces small, round to ellipsoid fruiting bodies called catathecia that measure 75–110 micrometres (μm) in diameter and are about 45 μm tall. These structures are scattered across the surface of the host lichen and can be seen with a hand lens. The upper wall of the catathecia is dark brown with a greyish tinge when treated with potassium hydroxide solution (K+) and is composed of rectangular or square cells arranged in radiating rows.
Around the spore-releasing pore (ostiole), there are 5–8 converging bristles called that measure 13-22 μm long. These setae are dark brown, thin-walled, and smooth, becoming swollen at their base but tapering toward the tip. The spore-producing structures (asci) are broadly club-shaped, somewhat curved, and contain eight spores each. The asci measure 33–43 by 9–10 μm. The spores themselves are hyaline (colourless), ellipsoid in shape, divided into two cells (1-septate), and measure 11–15 by 3–3.5 μm. Each spore typically has three pairs of small, hair-like appendages called setulae.
Habitat and distribution
Lichenopeltella lobariae has initially found growing on the lower surface of Lobaria pulmonaria thalli (the main body of the lichen), specifically in areas that lack the characteristic woolly covering () typical of this lichen species. At the time of its initial description, it was only known from two localities: one in France and one in Spain. The species appears to be closely related to L. santessonii, but can be distinguished by its smaller spores and the presence of setulae, as well as its different host preference, as L. santessonii grows on Peltigera species. In 2014, its known geographic and host range was expanded when it was reported in the Irkutsk region of Russia growing on Nephroma arcticum, and from Ecuador.
References
Microthyriales
Fungus species
Fungi described in 1996
Fungi of Europe
Fungi of Russia
Fungi of South America
Lichenicolous fungi
Taxa named by Paul Diederich
Taxa named by Javier Angel Etayo Salazar | Lichenopeltella lobariae | [
"Biology"
] | 629 | [
"Fungi",
"Fungus species"
] |
78,704,507 | https://en.wikipedia.org/wiki/Kynuramine | Kynuramine is a chemical compound with the molecular formula . It is the prototypical member of the class of biogenic amines known collectively as kynuramines. Kynuramine is produced by the decarboxylation of kynurenine and is a metabolite of tryptophan.
Kynuramine is an α-adrenoceptor inhibitor.
In biochemistry, kynuramine has been used as a substrate in assays used to measure amine oxidase activity.
References
Anilines
Amines
Aromatic ketones | Kynuramine | [
"Chemistry"
] | 117 | [
"Amines",
"Bases (chemistry)",
"Functional groups"
] |
78,706,669 | https://en.wikipedia.org/wiki/Taniborbactam | Taniborbactam (development code VNRX-5133) is a pharmaceutical drug that acts as a β-lactamase inhibitor. It inhibits the function of bacterial β-lactamases which impart resistance to β-lactam antibiotics. However, unlike other β-lactamase inhibitors that are used as pharmaceuticals, taniborbactam is effective against enzymes of the New Delhi metallo-beta-lactamase 1 group which are the most frequently identified sources of acquired antibiotic resistance worldwide.
Taniborbactam, in combination with cefepime, is in clinical trials for the treatment of bacterial infections, including urinary tract infection and pyelonephritis.
References
Beta-lactamase inhibitors
Amides
Benzoic acids
Cyclohexanes
Diamines
Boron heterocycles
Heterocyclic compounds with 2 rings | Taniborbactam | [
"Chemistry"
] | 186 | [
"Amides",
"Functional groups"
] |
78,707,119 | https://en.wikipedia.org/wiki/Ammonium%20hypoiodite | Ammonium hypoiodites are a class of reactive intermediates used in certain organic oxidation reactions. They consist of either ammonium itself or an alkylammonium with various substituents as cation, paired with a hypoiodite anion as the active oxidant. The hypoiodite is generated in situ from the analogous iodide reagent using peroxides, oxone, peracids, or other strong oxidizing agents. The hypoiodite is then capable of oxidizing various organic substrates. The iodide is regenerated, meaning the reaction runs with the iodide/hypoiodite as a catalyst in the presence of excess of the original strong oxidizing agent.
Ammonium hypoiodites are capable of oxidizing benzylic methyl groups, initiating oxidative dearomatization, and oxidative decarboxylation of β-ketolactones. Similar to the β-ketolactone reaction, oxidative ether formation can be performed at the alpha position of various ketones. Using chiral ammonium cations can give high enantioselectivity of the alpha-etherification reaction, an example of an efficient chiral metal-free organocatalysis process.
Several guanidinium hypoiodites can also be used in the various oxidative-coupling reactions. The guanidinium cation has the added benefit of forming multiple ionic interactions or hydrogen bonds to the substrates. The conjugate acid of triazabicyclodecene is especially effective.
References
Hypoiodites
Oxidizing agents
Ammonium compounds
Guanidinium compounds | Ammonium hypoiodite | [
"Chemistry"
] | 357 | [
"Redox",
"Oxidizing agents",
"Salts",
"Organic compounds",
"Hypoiodites",
"Ammonium compounds",
"Organic compound stubs",
"Organic chemistry stubs"
] |
78,707,585 | https://en.wikipedia.org/wiki/TARGET%20Services | TARGET Services (for Transeuropean Automated Real-time Gross-settlement Express Transfer) are payment services operated by the Eurosystem for the euro area and beyond on its proprietary financial market infrastructures.
As of late 2024, TARGET Services included T2 for large payments (which replaced TARGET2 in 2023), TARGET2-Securities (T2S) for securities transactions, and TARGET Instant Payment Settlement (TIPS) for instant payments. A fourth service, the Eurosystem Collateral Management System (ECMS), is to complement the TARGET suite in mid-June 2025.
History
In 1993, as the Maastricht Treaty entered into force, central banks of the EU agreed that all of them should have an real-time gross settlement (RTGS) system, as some had already done in the previous decade. In 1995, they decided to interlink these national infrastructures through a pan-European system that they called TARGET. That original TARGET system duly began operations on . Its first version had a decentralized structure that consisted of the national RTGS systems of the 12 euro area member states plus those of Denmark (KRONOS), Sweden (E-RIX), and the UK (CHAPS) together with the ECB Payment Mechanism (EPM). On , Poland was the first new EU member state following the 2004 enlargement to connect to TARGET, via its SORBNET-EURO RTGS system operated by the National Bank of Poland.
The first TARGET was replaced with TARGET2, a more centralized system based on a Single Shared Platform (SSP), in stages from November 2007 to May 2008. In addition to euro area countries and those that would adopt the euro in subsequent years (namely Cyprus, Malta, Slovakia and the Baltic countries), Denmark and Poland participated in the migration to TARGET2, whereas Sweden and the UK did not. On , Romania also connected to TARGET2.
In June 2015, TARGET2 participants were first allowed to open a Dedicated Cash Account (DCA) on the T2S platform, marking the start of the T2S service. In October 2018, T2S allowed settlements in Danish krones (DKK) in addition to those in euros.
TIPS was introduced in November 2018. On , Sweden completed its integration into TIPS, allowing for TIPS to also settle instant payments in Swedish kronas.
TARGET2 was replaced with T2 in March 2023. T2 and TIPS will also allow settlements of DKK payments in March 2025.
Legal structure
While technically integrated at the European level since the transition to TARGET2 in 2008, TARGET Services are based on contractual arrangements between participants and national entities known as TARGET components. The contractual conditions are harmonized in a formal Eurosystem document known as the TARGET Guideline last updated in 2022.
Controversy
TARGET2 imbalances
During the euro area crisis of the 2010s, cross-country imbalances within the TARGET2 system became an object of heated discussion, particularly in Germany.
Outage
In October 2020, TARGET2 and T2S experienced an outage for nearly 11 hours.
See also
Fedwire
References
European Union financial market policy
Real-time gross settlement
Securities clearing and depository institutions
Central securities depositories
Payment clearing systems | TARGET Services | [
"Technology"
] | 659 | [
"Real-time gross settlement"
] |
78,710,425 | https://en.wikipedia.org/wiki/C/1921%20H1%20%28Dubiago%29 | Dubiago's Comet, formally known as C/1921 H1 by its modern nomenclature, is a faint Halley-type comet that completes an orbit around the Sun once every 61–79 years. It was predicted to return in 1982, but it was not observed. It will next return to the inner Solar System by 2041.
Discovery and observations
The comet was first spotted from the Kazan Observatory on the evening of 24 April 1921. Initially, the discovery of the comet was incorrectly credited to Dmitri Dubyago, but the attribution was later clarified to Alexander Dubyago a year later.
References
External links
Halley-type comets | C/1921 H1 (Dubiago) | [
"Astronomy"
] | 132 | [
"Astronomy stubs",
"Comet stubs"
] |
78,711,654 | https://en.wikipedia.org/wiki/Nomad%20%28eSIM%20company%29 | Nomad is a company that sells eSIMs (embedded SIMs), launched in 2020.
History
Nomad was launched in 2020 and is a business line of LotusFlare, Inc., a telecommunications software development company founded by former Facebook and Microsoft engineers.
Nomad is a connectivity marketplace that offers mobile data plans worldwide supplied by various communications service providers. International travelers with eSIM-capable smartphones can buy data plans from local providers, reducing roaming costs. eSIMs can be purchased through the website or the smartphone app.
Plans include global eSIMs covering most countries and regional plans for specific areas such as Europe, Asia-Pacific, and Oceania. These plans cater to both short-term trips and extended stays.
It is a data-only service, meaning it doesn't support traditional cellular voice calls or SMS messaging, but the speeds are fast enough to handle voice and video chat via apps like FaceTime or WhatsApp.
In 2024, Nomad also launched Nomad eSIM Enterprise for business travelers.
Nomad has been featured in articles by The New York Times, Wall Street Journal, and CNBC.
Conflict in Gaza
Nomad has been used to connect civilians during communication blackouts in the Gaza war zone.
See also
eSim
Airalo
References
External links
Application software
Mobile applications
Technology companies
Mobile technology companies
Wireless networking
Travel technology
2020 establishments
2020 establishments in the United States
ESIM companies | Nomad (eSIM company) | [
"Technology",
"Engineering"
] | 283 | [
"Computer networks engineering",
"ESIM companies",
"Wireless networking",
"Mobile technology companies"
] |
78,712,317 | https://en.wikipedia.org/wiki/Tectonics%20%28architecture%29 | In modern architectural theory, the tectonics is an artistic way to express the corporeality of a building through architectural forms that reflect the actual structure. An example of the use of tectonics and its opposite, atectonics, can be found at the AEG turbine factory: Peter Behrens, the architect, had applied tectonics by revealing the steel frame that supports the roof on the long side of the building, and used atectonics by constructing massive "Egyptian-like" walls in the corners that are not connected to the roof and thus conceal the actual load and support organization of the frontal facade.
This "poetics of construction" has multiple related meanings.
Tectonics is inseparable from the actual buildings and thus counteracts external influences of other visual arts on architecture.
History
The word "tectonic" comes from , "carpenter, builder" that eventually led to master builder, (now architect). First application to modern architecture belongs to Karl Otfried Müller, in Handbuch der Archaologie der Kunst (Handbook of the Archeology of Art, 1830) he defined the art forms that combine art with utility (from utensils to dwellings) as , with the architecture being the peak of this tectonic activities. Karl Botticher in his Die Tektonik der Hellenen (The Tectonic of the Hellenes, 1843-1852) suggested splitting the design into a structural "core-form" () and decorative "art-form" (). Art-form was supposed to reflect the functionality of the core-form: for example, rounding and tapering of the column should suggest its load-bearing function. Tectonic system was supposed to bind these multiple facets of a building (Greek temple) into a unified whole (for example, through relief sculptures using structural elements as framing).
Atectonics
Atectonics is an inverse of tectonics, a situation where the artistic appearance of the architectural form is detached from its structure and construction. Eduard Sekler introduced the concept of atectonics in 1911 as the arrangement where the interplay between load and support is "visually neglected or obscured". An architect can use both the tectonics and atectonics simultaneously (cf. the AEG turbine factory example above). Even if the construction and structure are interdependent and exposed, like in the Crystal Palace, there is some space left for the atectonics (while the columns in this building carried different loads, they all appeared to be of the uniform width, with load variations accommodated through the thickness of their walls).
References
Sources
Architectural theory | Tectonics (architecture) | [
"Engineering"
] | 540 | [
"Architecture stubs",
"Architectural theory",
"Architecture"
] |
78,714,127 | https://en.wikipedia.org/wiki/List%20of%20steel%20manufacturers%20in%20Afghanistan | This is a list of steel manufacturers in Afghanistan:
Maihan Steel Mill in Kabul, Kabul Province
Milat Steel Mill in Shakardara District, Kabul Province
Khan Steel Mill in Kabul, Kabul Province
See also
List of companies of Afghanistan
References
External links
Afghanistan
Lists of companies of Afghanistan
Industry in Afghanistan | List of steel manufacturers in Afghanistan | [
"Chemistry"
] | 60 | [
"Steel industry by country",
"Metallurgical industry by country"
] |
78,719,019 | https://en.wikipedia.org/wiki/IC%205063 | IC 5063 is a post-merger system and is a Seyfert 2 galaxy. This active galactic nucleus (AGN) produces on the one hand interactions with the interstellar medium (ISM) and large radio outflows. On the other hand, the accretion disk around the supermassive black hole, produces crepuscular rays. It is the first discovered case of a black hole disk producing such rays, but circumstellar disks around some young stars are already known to produce similar shadows. The crepuscular rays were first noted in an image by Judy Schmidt, who posted her image of IC 5063 on the social media platform Twitter.
A smaller galaxy, called IC 5064, is located to the south of IC 5063. These two galaxies have a similar redshift and form a pair of galaxies.
AGN
IC 5063 was studied with ESO and CTIO instruments in 1991. This showed that the system is a post-merger system and has an extended-emission line region (EELR) in the galaxy nucleus. EELRs usually show strong emission due to doubly-ionized oxygen [O III]. In this work for the first time the X-shape of the emission was noted. The first radio observation of the galaxy was published in 1998. This included radio continuum and H I region mapping with the Australia Telescope Compact Array. The radio emission is aligned with the emission by [O III]. The oxygen emission of [O III] was also imaged in higher resolution with Hubble WFPC2 and published in 2003. In 2021 VLT/MUSE observations were published, including IC 5063. This showed that the [O III] extends up to around 10 kpc on each side. Modelling has shown that the jet is expanding in a gaseous disk in the nucleus, destroying and displacing clouds in the central region.
Various other molecular and atomic emission lines associated with the outflow were detected with various telescopes. A molecular outflow was first detected in carbon monoxide (CO) in 2013 with the Atacama Pathfinder Experiment. The researchers suggested that the jet is accelerating molecules. In 2014 this was confirmed, by showing that the jet is accelerating hydrogen gas molecules (H2) in a gaseous disk. This was based on spectroscopic observations with VLT/ISAAC. The researchers measured a speed of 600 km/s relative to the disk. More detailed observations with ALMA showed a fast outflow of cold gas imaged in carbon monoxide (CO). The entire jet has a size of 1 kpc and CO showed a speed of 650 km/s at 0.5 kpc. A later study, also using ALMA, found speeds of 800 km/s and a molecular outflow mass of more than 1.2 × 106 . Near-infrared observations with VLT/SINFONI showed signatures of molecular and atomic gas that are distorted by the radio jet. The galaxy was observed with JWST MIRI. This observation has shown that the gas sometimes exceeds the local escape velocity. Bow shocks in H2 show that the entire jet is more extended than seen in radio. A giant loop of low ionized sulfur and nitrogen was observed perpendicular to the radio jet.
The crepuscular rays, extending more than 11 kpc, were discovered in 2020 with Hubble observations. These are located perpendicular to the emission line region and the radio jets. Bright rays in the middle of the dark regions might indicate gaps in the obscuring material. From the shape of the dark rays it was estimated that the AGN torus has a wide opening angle of ≥137°. The rays could also be explained by LINER-like outflows and bubbles that expand in a lateral direction, as is seen in one bubble in IC 5063.
Gallery
References
5063
Indus (constellation)
Seyfert galaxies
Lenticular galaxies
65600 | IC 5063 | [
"Astronomy"
] | 807 | [
"Indus (constellation)",
"Constellations"
] |
78,719,379 | https://en.wikipedia.org/wiki/James%20Yeku | James Túndé Yékú is a Nigerian-Canadian writer and associate professor of African and African-American Studies at the University of Kansas. He specialises in African literary and cultural studies, and digital humanities research. His research interests include: African literature, digital humanities, Social media, cultural studies, postcolonial and decolonial theories, and Nollywood. He has published widely on different subjects across these fields.
Yékú is the author of Cultural Netizenship: Social Media, Popular Culture, and Performance in Nigeria (Indiana University Press, 2022), and the poetry collection Where The Baedeker Leads: A Poetic Journey, which received an honorable mention for the 2023 African Literature Association Best Book Award for creative writing. Yeku's poetry and essays have been published in various literary journals and mediums.
Education
James Yékú trained as a literary and cultural studies scholar at Ibadan and Saskatoon. He received his bachelor's and master's degrees in English, and Performance Studies respectively at the University of Ibadan in 2008 and 2012 respectively. He earned his Ph.D. in English at the University of Saskatchewan in 2018.
Career and Recognition
Yékú was engaged as a lecturer at the University of Saskatchewan's Department of English from 2017 to 2018. A year later, he moved to the University of Kansas where he is currently an associate professor at its Department of African and American Studies and the Institute for Digital Research in the Humanities.
Yékú was the winner of the 2022 Pius Adesanmi Early Career Research Excellence Award from the Canadian Association of African Studies. His journal article "Akpos Don Come Again: Nigerian Cyberpop Hero as Trickster" in the Journal of African Cultural Studies won the 2017 Abioseh Porter Best Essay Award of the African Literature Association. He has also received other awards and fellowships, which include a 2022 Center for Advanced Internet Studies fellowship in Bochum, as well as a 2023 Cultural Entrepreneurship and Digital Transformation in Africa and Asia international guest fellowship at the University of Mainz, both in Germany. He is also a recipient of the Alexander von Humboldt Foundation fellowship. Yékú currently spearheads African Digital Humanities initiatives at the University of Kansas and co-organizes the annual African Digital Humanities Symposium.
Selected publications
References
University of Ibadan alumni
University of Saskatchewan alumni
University of Kansas faculty
Nigerian writers
Digital humanities
Canadian people of Nigerian descent
Year of birth missing (living people)
Living people | James Yeku | [
"Technology"
] | 491 | [
"Digital humanities",
"Computing and society"
] |
78,721,739 | https://en.wikipedia.org/wiki/List%20of%20American%20isthmian%20canal%20engineers | This is a partial list of the civil engineers who helped plan, design, or build canals in Central America from 1848 to 1984.
Atlantic and Pacific Ship Canal Company survey of 1850
The Nicaraguan government chartered the company in 1846 to construct a canal in that country. It was chartered in the State of New York in the United States in 1854.
Lane, James Crandall (1823–1888) surveyed the Atrato, Pato, and Baudo rivers in 1854, which was then called New Granada, now Colombia.
In 1850, Cornelius Vanderbilt sponsored a survey of possible Nicaragua routes.
Childs, Orville Whitmore, Colonel (1803–1870), the builder of the Champlain and Oswego canals in New York State, was chief engineer for the 1850 survey. Childs found the lowest point in "the Continental Divide between Alaska and Cape Horn.." at the isthmus of Rivas, Nicaragua, above sea level.
Panama Railroad Company of 1848 – 1958
The Panama Railroad was a railway line linking the Atlantic Ocean to the Pacific Ocean in Central America.
Hughes, George W. Bvt. Lt. Col. (1820-1897) In 1849, Hughes surveyed the route location for the Panama railroad to Panama City.
Totten, George Muirson (1808-1884) Totten was chief engineer for the railroad (1856-1875).
Kelley surveys of 1855 – 1866
Frederick M. Kelley (1822 – 1905) was a Wall Street banker who sponsored seven expeditions to discover the purported "Sea Level Interoceanic Canal" of the Isthmus of Darien.
Kennesh, Wiliam (1799 – 1862) In late 1854, Kennish led an expedition across the Isthmus of Panama. He proposed a canal route via the Atrato-Truando rivers, suggesting the construction of tunnels to cross the Baudó Range.
Lane, James Crandall (1823 – 1888) was a distinguished American civil engineer and military officer notable for his contributions to engineering projects and service during the American Civil War. Lane led expeditions for the Atlantic and Pacific Canal company in 1853 and 1854, focusing on the same region. His surveys provided further insights into the feasibility of constructing a canal through the Atrato River basin.
William C. Fox, Henry P. Adams, and S. Lee Perkins (1827 – ) accompanied Lane.
Porter, Mark B., led an expedition in 1853.
Trautwine, John Cresson (1810 – 1883) In 1852, Trautwine led an expedition to survey the Atrato and San Juan rivers in present-day Colombia.
Isthmus of Darien survey of 1857
Michler, Nathaniel (1827 – 1881) Michler was an officer in the United States Army Corps of Topographical Engineers.
Nicaragua expedition of 1872
In 1872, the U.S. Navy Department initiated an expedition to survey a potential interoceanic canal route through Nicaragua.
Crowell, J. Foster, (1848 – 1915), surveyed the Rio Sapoa and Rio Ochomogo valleys.
Hatfield, Chester, (1837 – 1879), USN.
Keller, John D., USN surveys of Lake Nicaragua.
Leutze, Eugene Henry Cozzens,(1847 – 1931) USN, ran surveying operations, valleys of the Ochomogo Costa Rica, Tipitapa and San Juan, Nicaragua routes.
Lull, Edward Phelps (1836-1887), USN. Lull led the Nicaragua Exploring Expedition from 1872 to 1873, conducting comprehensive surveys for a potential interoceanic canal through Nicaragua.
Menocal, Aniceto García (1836 – 1908) Chief civil engineer, a Cuban-American civil engineer and naval officer.
Miller, James Madison.,(1852 – 1908), USN. USN, surveyed Greytown harbor.
Rhoades, William W. (1837 – 1893) USN surveyed the Rio Las Lajas route.
The Interoceanic Canal Commission of 1872
During the same period as the US Navy surveys, the United States Congress appointed another commission to recommend a route for an isthmian canal.
Humphreys, Andrew Atkinson (1810 – 1883), Brig. Gen, US Army Corps of Engineers.
Patterson, Carlile Pollock (1816 – 1881) United States Coast Survey
McFarland, Walter (1847– 1888) Maj., US Corps of Engineers surveyed the Nicaragua, Darien, and Atrato River routes.
International Canal Congress of 1879
This congress, held in Paris, France, was designed to determine the best location for a canal across the Isthmus.
Nicaragua Canal Association (1887)
The Association was chartered in 1887 with concessions from Nicaragua and Costa Rica.
In 1889
the Association was granted an American concession in the name of the Maritime canal company of Nicaragua to build a canal across Nicaragua. The Atlantic and Pacific Ship Canal Company protested this concession.
The Maritime Canal Company formed a subsidiary, the Nicaragua Canal Construction Company, to build the canal.
Le Baron, J. Francis (1847 – 1935)
Nicaragua Canal Commission of 1895 – 1897
Haines, Peter Conover, (1840 – 1921)
The Isthmian Canal Commission of 1899 – 1901
This Isthmian Canal Commission was created to recommend the best location in Central America to build a canal.
Burr, William Hubert (1851 – 1934). As a consulting engineer, Burr was also involved with the design of several bridges, tunnels, and infrastructure projects.
Ernst, Oswald Herbert USACE, (1842 – 1926) Ernst had been Superintendent of the U.S. Military Academy (1893 – 1898).
Haines, Peter Conover, USACE, previously a member of the previous Nicaragua Canal Commission.
Haupt, Lewis Muhlenberg (1844 – 1937), formerly USACE and a member of the previous Nicaragua Canal Commission.
Morison, George Shattuck (1842 – 1903) A classics major at Harvard who trained to be a lawyer, he instead became a civil engineer and leading bridge designer in North America during the late 19th century.
Noble, Alfred (1844 – 1914), who was best known for his work on canals and also served on the Nicaragua Canal Commission in 1895.
Isthmian Canal Commission of 1904 – 1914
This Isthmian Canal Commission managed the construction of the Panama Canal in the early years of American involvement and control of the Panama Canal Zone.
Wallace administration (1904 – 1905)
The following men were engineering members of the Commission during this period.
Wallace, John Findley (1852 – 1921) He was the first Chairman of the Isthmian Canal Commission and Chief Engineer.
Endicott, Mordecai T. Endicott (1844 – 1926), First civil engineer to head the Bureau of Yards and Docks.
Ernst, Oswald Herbert USACE, (1842 – 1926) Ernst had been Superintendent of the U.S. Military Academy (1893 – 1898) and also served on the 1899-1901 Isthmian Canal Commission.
Haines, Peter Conover, USACE (1840 – 1921). Haines had served on the previous Nicaragua Commission in 1895 and the first Canal Commission in 1899.
Other engineers were
Baucus, William (1866 – 1936). As a civilian, Baucus served as a consulting engineer for waterworks and sewerage systems with the Municipal Engineering Department in Panama. He contributed to the construction of the pipelines for the Pedro Miguel locks.
Dauchy, Walter Edward (1855 – 1941). Dauchy, as a civilian, was the division engineer for the Culebra Cut section of the Panama Canal. During Chief Engineer John F. Wallace's absences, he served as Acting Chief Engineer.
Goldmark, Henry C. (1857 – 1941) Goldmark managed the design and construction of the steel gates for the Canal locks from 1906 to 1914.
Jované, Ricardo Abel Arango (1881 – 1942). Jovane, a Panamanian civilian, was a civil engineer under the Colombia and Panama governments. In 1904, he was a division engineer in Ancon, Panama, and after the canal was completed, he became the chief engineer of the Republic of Panama.
Stevens administration (1905 – 1907)
The following men were engineering members of the Commission during this period.
Stevens, John Frank (1853 – 1943). He was the second Chairman of the Isthmian Canal Commission and Chief Engineer.
Goethals administration (1907 – 1914)
The following men were engineering members of the Commission during this period.
Goethals, George W. USACE (1858 – 1928), managed the administration and supervision of the construction and the opening of the Panama Canal (1907-1914). He was the third Chairman of the Isthmian Canal Commission, as well as Chief Engineer.
Gaillard, David du Bose USACE (1859 – 1913), USACE. Gaillard was in charge of crossing the continental divide, or the notorious Culebra Cut, through the backbone of the isthmus.
Harding, Chester USACE (1866 – 1936). Harding was the Division Engineer of the Gatun Locks Division from 1907 to 1914, then the Panama Canal maintenance engineer in January 1915, and the Panama Canal Zone governor from January 1917 to March 1921.
Hodges, Harry Foote, USACE (1860 – 1929). Hodges served as General Purchasing Officer, assistant chief engineer, and member of the Isthmian Canal Commission from 1907 to 1914.
Rousseau, Harry Harwood, USN (1870 – 1930), Chief of the Bureau of Yards and Docks and the Commission (1907-1914).
Other engineers were
Abbot, Henry Larcom (1831 – 1927) Abbott was appointed to the Board of Consulting Engineers by Theodore Roosevelt and served between 1905 and 1906 after the Americans took control of building the canal.
Cole, Harry Outen, (1874 - 1950) As a civilian engineer, Cole worked in various positions and eventually became the resident engineer in charge of lock and dam construction for the Pacific Division (1909-1914).
Comber, William George (1855 - 1923). Comber, a civilian engineer, was Resident Engineer of the Cristobal Division (1905-1907). Division Engineer La Boca Dam and Dredging Division. Resident Engineer in charge of all marine work in the Pacific Division
Cornish, Lorenzo Dana (1877 – 1934). Lorenzo, a civilian engineer, worked as a design engineer in the Chief Engineer's office (1907 – 1914).
Hoffman, George Mathias, USACE (1860 – 1923), Hoffman was the resident engineer on the Gatun dam and spillway project (1908 – 1913).
Jadwin, Edgar, USACE (1865 – 1931) Jadwin was Resident Engineer of the Atlantic Division (1907 – 1914).
Hagan, James Monroe (1881 – 1955) Hagan, a civilian engineer, was the Superintendent for the Construction of the Empire District, which extended from the Empire Bridge to the Gamboa Bridge.
Jervey, James Postell, USACE (1869 – 1947). Jervey was a resident engineer in the Atlantic Division overseeing the masonry construction of the Gatun Locks (1908 – 1913).
Jewel, Lindsey Louin (1877– 1915). Jewel worked with the McClintic-Marshall Construction Company of Pittsburgh, Pa., and managed the construction of the lock gates (1910 - 1912). In 1912, Jewel organized the Central American Construction Company as its President and Chief Engineer.
Johnson, Ben USACE (1866 – 1940) Johnson supervised excavation of the Metachin Cut and of the Mindi Approach to the Panama Canal (1907) and superintendent of excavation and concrete construction of the Gatun Locks (1909).
Johnson, Natt M. (1877 – 1960) As a civilian engineer, Johnson worked on survey parties and in various positions associated with the production of concrete for locks and, finally, as supervisor of concrete construction.
Mears, Fredrick USACE (1878 – 1939). Mears worked on locating the new Panama Railroad (1906-1907), then as Constructing Engineer of the relocated line from 1907 to 1909, and finally as Chief Engineer of the Panama Railroad Company.
Monniche, Tollef Bache (1874 – 1958) As a civilian engineer, Monniche was a design engineer working on the mitered lock and emergency spillway gates.
Reynolds, William T. (1873 – 1913). Reynolds was Superintendent of Construction for the Culebra and Central divisions (1907 - 1913).
Rourke, Louis K. (1873 – 1933) Rourke was a civil engineer working first as Superintendent of Construction in the Culebra Division, then as Superintendent of Tracks and Dumps, and finally as Division Engineer of the Culebra Division. Rourke was a pivotal figure in managing the Culebra cut excavation.
George Homer Ruggles (1870 – ): As a civilian engineer, Ruggles located the David extension of the Panama Railroad and then served as assistant engineer of the Culebra and Central divisions.
Saville, Caleb Mills (1865 – 1960) As a civilian engineer, Saville worked on geotechnical investigations conducted for the Gatun dam and spillways and then construction (1907-1912).
Sherman, Edward Clayton (1877 – 1961). As a civilian engineer, Sherman was a Division Engineer in charge of all designs relating to the dam, lock and embankments, and other work.
Sibert, William Luther, USACE (1860 – 1935) . Silbert was responsible for the Gatun Locks and Dam, the West Breakwater in Colon, and the channel from Gatun Lake to the Pacific Ocean.
Stickle, Horton Whitfield, USACE (1875 – 1959). Stickle worked in the Atlantic division, securing sand, stone, and cement for the Gatun locks and spillway.
Tucker, Herman Franklin (1878 – 1955).
Wells, George M. (1880 – 1957). As a civilian engineer, Wells worked as an office engineer in charge of the Atlantic Division designing office
Nicaragua Canal Survey of 1929 – 1931
By 1928, growing interest in expanding canal capacity led Congress to pass a resolution calling for updated surveys in Nicaragua to reassess data from 1901. The initiative also explored the viability of adding a third set of locks to the Panama Canal and potentially transforming it into a sea-level waterway.
Groves, Leslie Richard (1896 – 1970) USACE. Groves assisted Sultan in compiling the final report.
Sultan, Daniel I. (1885 – 1947) USACE. Sultan was commander of the United States Army Engineer Battalion in Nicaragua. The battalion numbered 25 officers and 295 enlisted men.
Notes
References
History of United States expansionism
Historic Civil Engineering Landmarks
19th-century American engineers
United States history-related lists | List of American isthmian canal engineers | [
"Engineering"
] | 2,986 | [
"Civil engineering",
"Historic Civil Engineering Landmarks"
] |
78,721,991 | https://en.wikipedia.org/wiki/Axel%20Gadolin | Axel Vilhelmovich Gadolin (; 12June 1828 – 15December 1892) was a Finnish/Russian lieutenant general, and also a scientist in the field of artillery, metallurgy, mineralogy and crystallography. Gadolin was a professor at the Mikhailov Artillery Academy and the Saint Petersburg Institute of Technology, doctor of mineralogy from Saint Petersburg University, and academician of the St. Petersburg Academy of Sciences. He was awarded the Lomonosov Prize in 1868 for his work on crystallographic point groups.
Career
Gadolin was born in Somero in the Grand Duchy of Finland on 12June 1828. He was the nephew of the chemist Johan Gadolin.
Gadolin combined his military career with a scientific career in mineralogy, crystallography, and artillery sciences. Gadolin received his initial education at the Finnish Cadet School. In 1847 he was a second lieutenant in the Russian artillery service. Gadolin graduated from the Mikhailov Artillery Academy in 1849 and remained their to teach; his initial appointment was as a lecturer in physics. He was appointed director of the artillery school in 1856 (and promoted to captain), and then professor in 1866. In 1859 he was promoted to colonel, and in 1866 to major general. While at the artillery school he developed techniques for building high velocity canons, which significantly increased the range that a shell could be propelled.
In 1869 he was awarded an honorary doctorate of mineralogy by the council of Saint Petersburg University. In 1872 he became professor at Saint Petersburg Institute of Technology. Gadolin was promoted to lieutenant general in 1876.
Works
Gadolin published in the fields of artillery, mechanical engineering, metallurgy, mineralogy and crystallography.
Gadolin's most famous scientific work is entitled Deduction of all Crystallographic Systems and their Subdivisions by Means of a Single General Principle. It was first published in Russian in 1867, reprinted in 1954, translated into French in 1871, and German in 1896.
In this work Gadolin used the law of rational indices to prove that only 2-, 3-, 4-, and 6-fold axes are possible in crystals. He showed that it is possible to derive all the crystallographically possible polyhedra by studying how the elements of symmetry can be combined. Gadolin showed that the resulting polyhedra can be divided into 32 classes varying by symmetry. Gadolin stated that two crystals should belong to the same class if they have the same symmetry elements, identically disposed. This is the foundation of the modern classification into geometric crystal classes. Although he predicted 32 crystal classes, Gadolin found only 20 examples in nature. Gadolin work was often cited as the most important source for the systematic derivation of the crystal classes without using the concepts of group theory.
Moritz Ludwig Frankenheim in 1826 and Johann F. C. Hessel in 1830 had found the 32 crystal classes. Gadolin, who was unaware of the work of his predecessors, found them independently using stereographic projection to represent the symmetry elements of the 32 groups. Gadolin's work had a clarity that attracted widespread attention, and caused Hessel's earlier work to be neglected. Gadolin influenced the later crystallographic work of Paul Groth.
In 1883 Evgraf Fedorov completed his Elements of the theory of figures; Gadolin assisted in its eventual publication in 1885. Fedorov and Arthur Moritz Schoenflies added new symmetry elements such as glide reflection to those considered by Gadolin; using these new symmetry elements they enumerated the 230 space groups in three dimensions in 1891.
Gadolin's mineral collection is held at the Finnish Museum of Natural History.
Honours and awards
Military
Gadolin was the recipient of numerous military awards.
Order of Saint Anna, 3rd class, 1859; 2nd class, 1864; 1st class 1872
Order of St. Vladimir, 4th class 1862; 3rd class 1868; 2nd class 1875
Legion of Honour, commander (3rd class), 1867 (France)
Order of Saint Stanislaus, 1st class, 1870
Order of St. George, 4th class, 1871
Order of the White Eagle, 1879
Order of Saint Alexander Nevsky, 1884
Order of the Sword, commander grand cross (1st class), 1885 (Sweden)
Academic
Lomonosov Prize, 1868 for his work on crystallographic point groups
Saint Petersburg University, honorary doctorate of mineralogy, 1869
St. Petersburg Academy of Sciences, corresponding member, 1873; extraordinary academician, 1875; full academician, 1890
The mineral Axelite was named in honour of Axel Gadolin.
References
1828 births
1892 deaths
Crystallographers
Members of the Russian Academy of Sciences
Finnish military personnel
Imperial Russian lieutenant generals
Finnish mineralogists
Russian mineralogists
Recipients of the Order of St. George of the Fourth Degree
Recipients of the Order of Saint Stanislaus (Russian), 1st class
Recipients of the Order of St. Anna, 1st class
Recipients of the Order of St. Vladimir, 2nd class
Commanders of the Legion of Honour
Commanders Grand Cross of the Order of the Sword | Axel Gadolin | [
"Chemistry",
"Materials_science"
] | 1,037 | [
"Crystallographers",
"Crystallography"
] |
78,722,425 | https://en.wikipedia.org/wiki/GARDP | The Global Antibiotic Research and Development Partnership (GARDP) is a Swiss nonprofit pharmaceutical research and development organization that aims to assist antibiotic drug development to counter the threat of antibiotic resistance. It was founded in 2016 by the World Health Organization and the Drugs for Neglected Diseases initiative. GARDP became a Swiss foundation in 2018.
See also
CARB-X
References
External links
Non-profit corporations
Antimicrobial resistance organizations
Medical and health organisations based in Switzerland | GARDP | [
"Chemistry"
] | 95 | [
"Pharmacology",
"Pharmacology stubs",
"Medicinal chemistry stubs"
] |
78,725,498 | https://en.wikipedia.org/wiki/Minimum-diameter%20spanning%20tree | In metric geometry and computational geometry, a minimum-diameter spanning tree of a finite set of points in a metric space is a spanning tree in which the diameter (the longest path length in the tree between two of its points) is as small as possible.
In general metric spaces
It is always possible to find a minimum-diameter spanning tree with one or two vertices that are not leaves. This can be proven by transforming any other tree into a tree of this special form, without increasing its diameter. To do so, consider the longest path in any given tree (its diameter path), and the vertex or edge at the midpoint of this path. If there is a vertex at the midpoint, it is the non-leaf vertex of a star, whose diameter is at most that of the given tree. If the midpoint is interior to an edge of the given tree, then there exists a tree that includes this edge, and in which every remaining vertex is a leaf connected to the endpoint of this edge that is nearest in the given tree, with diameter at most that of the given tree.
Because of this special form, it is possible to construct a minimum-diameter spanning tree of points in time , assuming that the distance between two points can be computed in constant time. To do so, test all candidates for the single point or pair of points that are not leaves. Each single point can be tested in time. Each pair of points can also be tested in , after a precomputation step in which, for each point, the other points are sorted by their distance from it. To test a pair of points, start with a tree in which all remaining points are attached to one point of the pair, and then in decreasing order by distance from that point, reattach these points one at a time to the other point of the pair, keeping track of the diameter of the tree at each step. There are candidate pairs of non-leaf points, each of which can be evaluated in time , giving a total time bound of .
The problem of constructing a minimum-diameter spanning tree is different from computing the diameter of the given points, the maximum pairwise distance. For some sets of points, the diameter of the points and the diameter of their minimum-diameter spanning tree are equal; for others (for instance, three equidistant points) these two distances can differ from each other by a factor of two.
In graphs
For the metric space of shortest-path distances in a graph, a minimum-diameter spanning tree can also be a spanning tree of the graph, a tree whose edges all belong to the graph. However, this may require it to have more than two non-leaf vertices. In this case, the problem is equivalent to finding an absolute 1-center of the graph. This is a point in a metric space obtained from the given graph by replacing each edge by a continuous interval of the same length. That is, it can either be a vertex or it can lie partway along any edge of the given graph. Among such points, the absolute 1-center is a point minimizing the maximum distance to all vertices. The shortest-path tree from this point to all vertices in the graph is a minimum-diameter spanning tree of the graph. The absolute 1-center problem was introduced long before the first study of the minimum-diameter spanning tree problem, and in a graph with vertices and edges it can be solved in time .
In the Euclidean plane
The exact solution of the minimum-diameter spanning tree problem, in the Euclidean plane, can be sped up from to , at the expense of using complicated range search data structures. The same method extends to higher dimensions, with smaller reductions in the exponent compared to the cubic algorithm. In dimensions, the time bound for this method is
A polynomial-time approximation scheme is known for the minimum-diameter spanning tree in the plane. For any , one can find a tree whose diameter is at most times the optimum, in time . The algorithm involves approximating the input by the points of a coarse grid, chosen to give the best tree among a small number of grid orientations.
For points in the Euclidean plane, the minimum-diameter spanning tree problem can also be approximated by the minimum-sum dipolar spanning tree. This is a tree having two non-leaf vertices, minimizing the sum of two quantities: the distance between the two non-leaf vertices, and the largest distance from a leaf vertex to the closer of the two non-leaf vertices. This approximation can be found in time , and achieves an approximation ratio of .
With only one non-leaf
For the minimum-diameter tree among trees with only one non-leaf vertex, the non-leaf vertex of the tree is the 1-center of the points.
If additional Steiner points are allowed to be added to the given set of points, their addition may reduce the diameter. In this case, a minimum-diameter Steiner spanning tree exists with only one non-leaf vertex, a Steiner point at the center of the smallest bounding sphere of the points. Its diameter is twice the radius of this sphere. For points in a Euclidean space of bounded dimension, this sphere and this tree can be found in linear time using algorithms for the smallest-circle problem and its generalizations.
References
Spanning tree
Computational problems in graph theory
Geometric algorithms | Minimum-diameter spanning tree | [
"Mathematics"
] | 1,088 | [
"Computational problems in graph theory",
"Computational mathematics",
"Graph theory",
"Computational problems",
"Mathematical relations",
"Mathematical problems"
] |
78,727,875 | https://en.wikipedia.org/wiki/Heinrich%20Ernemann | Johann Heinrich Ernemann (28 May 1850, Gernrode, Eichsfeld–16 May 1928, Hartha), son of Catharina Ernemann and Joseph Brodmann, farmer, was a German inventor, entrepreneur and industrialist who contributed innovations in photography and cinema equipment, and was founder of Ernemann-Werke AG.
Entrepreneur
Born into a poor farming family, Heinrich Ernemann was educated in Gernrode only to the primary level. Leaving Eichsfeld in 1866, he worked at the Krupp Gussstahlfabrik in Essen until about 1870. Exempted from military service, he studied in the business school in Pirna before working as a commercial traveller. He moved to Dresden and on New Year's Eve of 1875 married Marie Therese (née Grafe) with whom he turned his mother-in-law's haberdashery store into a thriving business. Living frugally, by 1888 they had saved 7,500 marks with which Ernemann purchased a share in carpenter Wilhelm Franz Matthias's camera shop on Pirnaer Strasse in Eschdorf, establishing himself in the still-nascent photo industry. Recognising and developing the market for such goods, he gave their small backyard workshop the brand 'Dresden photographic apparatus factory,' producing bespoke portable and studio cameras. In January 1891, Matthias departed, unhappy with Ernemann's industrialisation.
Industrialist
Moving into larger premises in 1892 Ernemann then introduced steam power, contriving an operating structure necessary for industrial mass production and machinists to reduce dependence on suppliers for small metal parts. By May 1892 the company was granted its first patent, for a between-the-lens shutter, and published its first catalogue in 1896. Their 'Edison Universal' magazine camera of 1894 was the first to be stamped with the Ernemann name in an era when it was the retailers who branded the product.
In a visionary manner he thus expanded the company so that it became one of the most important photo and cinema companies in the German empire. Awards were received at prestigious trade shows, including the Great Trade and Art Exhibition in Dresden in 1896 confirming Ernemann, beside Emil Wünsche and Richard Hüttig, as one of the Saxon entrepreneurs in the photography industry whose businesses expanded, while others who did not industrialise were bankrupted or taken over; in 1909 even Wünsche and Hüttig were forced to merge as ICA (International Camera Aktiengesellschaft). The Berliner Borsen Zeitung reported in March 1899 that 'with the cooperation of the H. G. Lueder bank' Heinrich Ernemann's enterprise had been entered in the commercial register as a stock company under the name: 'Heinrich Ernemann Actiengesellschaft für Camera-Fabrikation Dresden', 'with a registered capital of 650,000 ℳ.' To protect his intellectual property Ernemann registered the trademark Lichtgöttin ('Goddess of Light'), used on the company's equipment productions until 1920, after which it was used only for their chemical products.
Meanwhile, in 1903 Ernemann introduced its first movie camera, the Kino, aimed at the amateur market. Entrepreneur and inventor Fridolin Kretzschmar had in 1902, prior to Ernemann, devised and sold his 17.5mm Kinematograph camera intended for the low end of the professional market. Roepke considers it is evidence of Ernemann's aggressive business acumen that, in seeing a larger amateur market for the device, he produced models nearly identical to Kretzschmar's, either through cooperation with the latter, or by purchasing the patients and forcing his rival out of business. The pocket-sized, 800 gram, Kino 17.5mm used unperforated 35mm film sliced lengthwise with sprocket holes that ran down the centre. It could be processed with a reversal development kit that Ernemann also provided, and the camera doubled as a projector when a lamp housing was attached. Nevertheless, though Ernemann was marketing the ingeniously compact device to amateurs and the home-movie hobbyists, purchasers had to be wealthy to afford it. In addition, he encouraged those who took it up to contribute their films to a catalogue of prints to which he added professional movies, and also Kretzschmar's, which could be purchased for home theatres. Later Ernemann and his son Alexander (1878-1956) produced educational and scientific films, for which Heinrich was awarded his honorary doctorate in 1924.
In 1897, Ernemann built a new factory in the same street as the ICA factory, Schandauer Straße in Dresden, a city which thus became a centre for the photography industry. By 1923 his factory incorporated the landmark Ernemann Tower which still stands, rebuilt after a fire which destroyed it in 1923.
His son Alexander, who in America had become expert in industrial efficiency, joined the company as technical manager in 1904 and restructured it, introducing quality control and a system of apprenticeships.
The company developed an international market. The German science, trade and industry magazine Prometheus, in a 1905 article about aerial photography from tethered balloons and kites, notes their recent use during the Russo-Japanese War when the Russian Topographical Institute in St. Petersburg had the Heinrich Ernemann Camera Manufacturing Company build special equipment for automatic balloon photographs in the East Asian theatre of war. These consisted of seven photographic cameras, one of which photographed directly downwards, while the other six were arranged in a circle around it and inclined with their axes at 30° to the horizontal and an angle of 60° between each other, so that at a height of 300 m above the ground, the entire terrain up to the horizon was photographed.
From 1907 the company ground its own lenses from Jena glass, and released a single-lens reflex and a 360º panoramic camera, the Rundblick. Their Imperator, a durable 35mm movie projector made from steel, an engineering advance on flimsy and unreliable existing models, was launched at the first International Photographic Exhibition, 'a collective representation of Photography in all its branches and in all civilised countries,' held in Dresden (on the board which, Ernemann served with Hugo Erfurth, C. P. Goerz, Dr. Adolf Miethe, Dr. Richard Neuhauss, and others) and was quickly taken up by almost all cinemas in Paris. At a 1911 trade fair the Ernemann company received the highest award for the projector, recording devices and amateur movie cameras.
World War I
Increasing expenditure on its 400 employees, plant and advertising caused financial strain but a mooted merger with ICA was avoided and after the company recovered quickly in 1910, Ernemann was knighted in the Order of Albrecht (First Class). In 1913 Frederick Augustus III, the King of Saxony, conferred upon him the title of Kön Kommerzienrat (Royal Counselor of Commerce) for Saxony. Before America declared war on Germany, the company had opened retail premises at 114 Fifth Avenue, New York City. The Photographische Chronik und Allgemeine Photographen-Zeitung of 1913 considered that: It is a pleasing sign of the development of the Ernemann-A.-G. and the popularity of its products that the company has already been able to undertake its third large expansion building since its foundation in 1899 without having to increase its share capital, since the expansions carried out could always be covered from current funds in addition to the payment of a satisfactory dividend. Likewise, during World War I, which halved its workforce, military purchases quickly restored the company's wealth and its employee numbers. Ernemann's prestige and influence continued to grow, so that in 1913 he was appointed to the Royal Saxon Commercial Council in the year that his new employee Dr. Hans Lehmann prototyped the Zeitlupen, an early slow-motion camera eventually capable of 1500 frames-per-second, as proven in demonstrations for the Dresden Scientific Society; and an aerial camera of critical value in the War.
Post-war
The end of the War confronted Ernemann with new financial difficulties that were remedied by cooperation with Friedrich Krupp AG to make and sell projectors; replacement of the Lichtgöttin logo by a Maltese cross gear symbol over the three Krupp rings; the licensing to manufacture J. P. Hansen's Norka studio camera; and the opening of a new chemical factory in leased, and in 1923, purchased, facilities in nearby Bannewitz.
The 1922/23 period of hyperinflation, during which the company produced for the government the 50 million Deutschmarks voucher, was followed by recovery and expansion of the Schandauer buildings to accommodate the then 3,500 workers, then a recession that halved that number.
The Ermanox
Company employee since 1919, and only twenty-three, the self-taught optical engineer Ludwig Bertele designed, under the supervision of August Klughardt, the ƒ2.0/125mm the design for a 'miniature' press camera, the Ermanox (Latin: nox, meaning night, darkness). A triplet lens into which he introduced an extra positive meniscus element, its advantage to low-light photojournalism, such as the famously and surreptitiously made by Erich Salomon of politicians, was due to its increased light-gathering power while reducing the aberrations that the wide aperture would otherwise introduce. In 1920 he widened the aperture to a then remarkable ƒ1.8, though Gernsheim notes that as the depth of field on its 4.5x6cm plates was rendered so extremely shallow at that aperture, many press photographers preferred the ƒ2.0.
Merger
Max Bruenner, writing on the Dresden industry in the American photo magazine Photo-Era in 1923 remarked:What reader has not heard of the firm of Ernemann, which sends its products to all parts of the world? As in many other branches, the German camera-industry owes its development to the creative ability of individuals who have performed in their special field untiring pioneer-work. Such a man, in Dresden, is Heinrich Ernemann.In 1926, Ernemann-Werke AG merged with Carl Zeiss, the Optical Institution C. P. Goerz, the International Camera Actiengesellschaft (ICA) and the Contessa-Nettel, as Zeiss-Ikon AG, for which Bertele continued innovations in lenses including the Sonnar series based on the Ernostar, and a wide-angle lens, the Boigon.
While the Dresden family business came to an end after 37 years, Heinrich Ernemann remained on the board of the new company.
Personal life and legacy
In 1908, after persuading thirteen fellow entrepreneurs to join him, Ernemann was instrumental in the creation of a chair for photography and a photo laboratory at the Technical University of Dresden, reflecting a desire of the photographic industry in Dresden to cooperate with the educational and research institutes. The group also supported a school for training photo retailers which in turn attracted 136 photographers and 90 manufacturers of photographic equipment and materials, as well as printing and press companies, to the city whose population then was a mere 399,740. Later, Ernemann and his son Alexander became founding members of the Society of Sponsors and Friends of the Technical University of Dresden. The awarding of the honorary doctorate (as Dr.-Ing. E. h.) of the Technical University of Dresden on 24. July 1924 was in appreciation of his life's work in the promotion of scientific and educational film.
Ernemann's wife Marie Therese had passed away on 22 August 1917, and eleven years later, he died aged 78 on 16 May 1928 in his summer villa Heinrichs Eck at 21 Am Hartheberg in the spa town of Hartha, built in 1900 and since restored. He was survived by his children Frieda Henriette Marie Therese (1876–1954), Alexander Karl Heinrich (1878–1956), Anna Katharina Gertrud (1880–1940), Dora Bertha Johanna (1883–1942) and Fritz Henry Otto (1886–1941). Heinrich Ernemann's grave is located in the Johannisfriedhof in Dresden-Tolkewitz.
The villa at 8 Justinenstraße in Dresden-Blasewitz, occupied in 1891 by the Ernemann family, was destroyed on 13 February 1945 in the bombing of Dresden, and its ruin was demolished in the post-war period. In its place today is a block of flats.
Ernemann's daughter Anna Katharina Gertrud was the mother of AEG manager C. Johannes G. Heyne.
References
German industrialists
1850 births
1928 deaths
German inventors
Photography in Germany
Photography
Cameras
| Heinrich Ernemann | [
"Technology"
] | 2,666 | [
"Recording devices",
"Cameras"
] |
74,370,052 | https://en.wikipedia.org/wiki/Sylvain%20Liberman | Sylvain Liberman (1934 – 5 August 1988) was a French physicist, specializing in atomic physics and laser spectroscopy. He is known as the leader of the scientific team that made the first measurements of the optical spectrum of francium.
Education and career
Sylvain Liberman received his doctorate in 1971 from Orsay's Paris-Sud University (Paris XI), which in 2020 was replaced by Paris-Saclay University. His dissertation is entitled Études de structures hyperfines et d'effets isotopiques dans les raies laser infrarouges de gaz rares (Studies of hyperfine structures and of isotopic effects generated by infrared lasers in spectrographic lines of noble gases). From 1971 until his death in 1988 he did research for the CNRS in Orsay and at the Laboratoire Aimé-Cotton (LAC). From 1981 until his death he was director of the Laboratoire Aimé-Cotton (which was jointly operated by the CNRS and the Paris-Sud University).
Liberman was involved in the development of a single-mode pulsed laser with excellent pointing stability. (Pointing stability is a measure (usually in mr or μr) of how much the laser beam position drifts from the target over time.) He and his colleagues developed an ultra-sensitive method for measuring optical resonances using either resonance ionization or deflections of atomic jets extracted from a magneto-optical trap. He also made contributions to the understanding of Rydberg states, spontaneous collective decays (superradiance, subradiance) and the hyperfine interaction of radioactive atoms, which he and his colleagues investigated at CERN using the ISOLDE facility. He and his colleagues found significant differences in nuclear properties from the study of hyperfine structure when studying isotopic families (such as cesium in the mass range 118 to 145 and potassium in the mass range 38 to 47). At CERN, he led the team credited with the first recording of a line of the optical spectrum of francium. Before that, francium was the only element with an atomic number below 100 for which no optical transition had been observed.
In 1985 he received the Prix des trois physiciens.
Selected publications
Articles
1985
1985
Books
(lectures in English at the physics summer school in Les Houches)
References
1934 births
1988 deaths
20th-century French physicists
Laser researchers
Spectroscopists
Paris-Saclay University alumni
Research directors of the French National Centre for Scientific Research
People associated with CERN | Sylvain Liberman | [
"Physics",
"Chemistry"
] | 518 | [
"Physical chemists",
"Spectrum (physical sciences)",
"Analytical chemists",
"Spectroscopists",
"Spectroscopy"
] |
74,370,559 | https://en.wikipedia.org/wiki/Berkelium%28III%29%20oxybromide | Berkelium(III) oxybromide is an inorganic compound of berkelium, bromine, and oxygen with the chemical formula BkOBr.
Synthesis
Berkelium oxybromide can be prepared by the action of a vapor mixture of HBr and on berkelium tribromide.
References
Berkelium compounds
Oxybromides | Berkelium(III) oxybromide | [
"Chemistry"
] | 74 | [
"Inorganic compounds",
"Inorganic compound stubs"
] |
74,371,211 | https://en.wikipedia.org/wiki/Maria%20Ib%C3%A1%C3%B1ez | Maria Ibáñez Sabaté is a Spanish materials scientist and Professor at the Institute of Science and Technology Austria. Her research considers functional nanomaterials for next generation technologies. She was awarded the ETH Zurich Ružička Prize in 2017.
Early life and education
Ibáñez studied physics at the University of Barcelona. She remained there for her doctoral research, where she developed synthesis strategies for colloidal nanoparticles. Her research originally considered materials for photovoltaics, but she became increasingly interested in thermoelectric materials. During her doctoral research she completed placements at the French Alternative Energies and Atomic Energy Commission, University of Chicago, California Institute of Technology, Cornell University and Northwestern. Her doctoral research was awarded the Extraordinary Award, the University of Barcelona's highest accolade. After earning her doctorate she joined ETH Zurich, where she worked with Maksym Kovalenko.
Research and career
In 2017 Ibáñez was awarded the Ružička Prize for her work on developing new thermoelectric materials. She joined the Institute of Science and Technology Austria as an assistant professor in 2018. She was promoted to the Verbund Professor for Energy Sciences in 2022.
Her research considers nanocrystals that can be used as building blocks to engineer metamaterials. She is interested in the development of solution processed thermoelectric materials with high Seebeck coefficients, electrical conductivities and thermal conductivities.
Select publications
Personal life
Ibáñez is married with two sons.
References
Year of birth missing (living people)
Living people
Women materials scientists and engineers
Materials scientists and engineers
21st-century Spanish scientists
21st-century Spanish women scientists
University of Barcelona alumni | Maria Ibáñez | [
"Materials_science",
"Technology",
"Engineering"
] | 344 | [
"Women materials scientists and engineers",
"Materials scientists and engineers",
"Women in science and technology",
"Materials science"
] |
74,371,509 | https://en.wikipedia.org/wiki/Pedersen%20current | A Pedersen current is an electric current formed in the direction of the applied electric field when a conductive material with charge carriers is acted upon by an external electric field and an external magnetic field. Pedersen currents emerge in a material where the charge carriers collide with particles in the conductive material at approximately the same frequency as the gyratory frequency induced by the magnetic field. Pedersen currents are associated with a Pedersen conductivity related to the applied magnetic field and the properties of the material.
History
The first expression for the Pedersen conductivity was formulated by Peder Oluf Pedersen from Denmark in his 1927 work "The Propagation of Radio Waves along the Surface of the Earth and in the Atmosphere", where he pointed out that the geomagnetic field means that the conductivity of the ionosphere is anisotropic.
Physical explanation
When a moving charge carrier in a conductor is under the influence of a magnetic field , the carrier experiences a force perpendicular to the direction of motion and the magnetic field, resulting in a gyratory path, which is circular in the absence of any other external force. When an electric field is applied in addition to the magnetic field and perpendicular to that field, this gyratory motion is driven by the electric field, leading to a net drift in the direction around the guiding center and a lack of mobility in the direction of the electric field. The charge carrier undergoes a helical motion whereby a charge carrier at rest acquires motion in the direction of the electric field according to Coulomb's law, gains a velocity perpendicular to the magnetic field, and subsequently is pushed in the direction due to the Lorentz force (as is in the direction of , is initially in the same direction as .) The motion will then oscillate backwards against the electric field until it again reaches a velocity of zero in the direction of the electric field, before again being driven by the electric and magnetic fields, forming a helical path. As a result, in a vacuum, no net current is possible in the direction of the electric field. Likewise, when there is a dense material with a high frequency of collisions between the charge carriers and the conductive medium, mobility is very low and the charge carriers are basically stationary.
For a positively charged particle, over the course of this helical path, there is a positive skew in the location distribution of the charge carrier in the direction of the electric field, such that at any given point in time a measurement of the location of the charge carrier will on average result in a positive change from original position in the direction of the electric potential. During a collision with another particle in the medium, the velocity of the charge carrier is randomized at the point of collision. This location of collision is likely to be a positive change in the direction of the electric field from the original location of the charge carrier. After the velocity is randomised, the charge carrier will then restart helical motion from a different original location. Overall, this results in a bulk movement in the direction of the electric field such that a current is able to flow, which is known as the Pedersen Current, with the associated Pedersen Conductivity reaching a maximum when the frequency of collisions is approximately equal to the gyratory frequency so that the charge carriers experience one collision for every gyration.
The Pedersen conductivity is determined by the following equation:
Where the electron density is , is the magnetic field, is the ion concentration for a given species, is the collision frequency between ion species i and other particles, is the gyrofrequency for that ion, is the collision frequency for the electron, and is the electron gyrofrequency.
A negative charge carrier undergoes a similar drift in the direction , but moves in the opposite direction to a positive charge carrier, and undergoes helical motion such that there is a net negative skew in the distribution of position from the original position over the gyration, and as these particles are negatively charged they will also produce a positive contribution to the Pedersen current.
Role in the Ionosphere
Pedersen currents play an important role in the ionosphere, especially in polar regions. In the ionospheric dynamo region near the poles, the ion density is low enough and the magnetic field high enough for the collision frequency to be comparable to the gyration frequency, and the Earth's magnetic field has a large component perpendicular to the horizontal electric field due to the high inclination of the field near the poles. As a result, Pedersen currents are a significant mechanism for charge carrier movement. The magnitude of the Pedersen current balances the drag on the ionospheric plasma due to ion‐neutral collisions.
Pedersen currents in the ionosphere are similar to Hall currents. They share similar production mechanisms, similar formulas for determining conductivity, and similar conductivity profiles and conductivity dependence on various factors. The Pedersen and Hall conductivities are maximised during daytime or in auroral regions at night, as they depend on plasma density, which in turn depends on auroral or solar ionization. The conductivities also vary by about 40% over the solar cycle, reaching a maximum conductivity around solar maximum.
The Pedersen conductivity reaches a maximum in the ionosphere at an altitude of around 125 km.
Pedersen currents flow between the Region 1 and Region 2 Birkeland current sheets (see the figure), completing the circuit of the flow of charge through the ionosphere (at a given local time, one region involves current entering the ionosphere along the geomagnetic field lines, and the other region involves current leaving the ionosphere.) There is also a Pedersen current that flows across the pole from the dawn side (local time 6:00) to the dusk side (local time 18:00) of the region 1 current sheet.
Electrons have also been shown to carry Pedersen currents in the D layer of the ionosphere.
Joule heating
The Joule heating of the ionosphere, a major source of energy loss from the magnetosphere, is closely related to the Pedersen conductivity through the following relation:
Where is the Joule heating per unit volume, is the Pedersen conductivity, and are the electric and magnetic fields, and is the neutral wind velocity.
See also
Electromagnetism
Magnetohydrodynamics
References
Electromagnetism
Electricity | Pedersen current | [
"Physics"
] | 1,276 | [
"Electromagnetism",
"Physical phenomena",
"Fundamental interactions"
] |
74,375,407 | https://en.wikipedia.org/wiki/ITU-T%20G.9991 | ITU-T G.9991 (provisionally known as G.vlc) is a standard developed by ITU-T for indoor line-of-sight optical networking.
G.9991 was approved in March 2019. It is used by Signify (formerly Philips Lighting) as the basis for their optical communication products.
References
See also
IEEE 802.11bb, an IEEE standard for line-of-sight optical networking approved in 2023
IrDA, an early low-speed infrared communication protocol
ITU-T G Series Recommendations | ITU-T G.9991 | [
"Technology"
] | 111 | [
"Computing stubs",
"Computer network stubs"
] |
74,375,642 | https://en.wikipedia.org/wiki/Ice%20mass%20balance%20buoy | An ice mass balance buoy (IMB) allows scientists studying sea ice to measure its temperature and the evolution of its interfaces remotely. The autonomous mass balance buoys usually consist of a data controller module and a temperature string. Some ice mass balance buoys also include acoustic sounders above and below ice measuring the positions of the snow-ice and ice-water interfaces.
Types
The main types of ice mass balance buoys include
The CRREL-Dartmouth Ice Mass Balance (IMB) Buoy
Snow and Ice Mass Balance Array (SIMBA) from SAMS
Seasonal Ice Mass Balance buoy (SIMB-1,2,3)
The CRREL-Dartmouth Ice Mass Balance Buoy (IMB) includes two ice-facing acoustic rangefinders, a vertical temperature string, and air temperature and pressure sensors. These sensors are connected to a non-floating satellite-connected transmission package. Seasonal Ice Mass Balance Buoy (SIMB-1). The SIMB-1,2,3 instruments have the same sensor package as the CRREL-Dartmouth IMB but are enclosed in a spar-type buoy hull to improve their performance during the melt season. The lower-budget Snow and Ice Mass Balance Array (SIMBA) from SAMS includes only a vertical temperature string and a non-floating satellite-connected transmission package.
Characteristics
The main part of IMBs is a vertical chain of thermistors. The vertical spacing of the thermistors at modern IMBs is usually around 2–4 cm. The accuracy of each sensor is generally within 0.1–0.5°C. Many modern IMBs measure in-situ temperatures and temperatures after a cycle of internal heating. In experimental fluid dynamics, such a mode is called a “hot-wire anemometer”. In IMBs, the heat is added by applying an excitation voltage to the resistor bonded to the temperature sensor. The temperature response of the sensor during heating depends on the thermal diffusivity of the surrounding medium (for solids like snow or ice) and the flow rate of the medium (for fluids like seawater or air). The heat transfer in fluids depends on the fluid velocity, and the response usually varies over time scales. The measurements of the temperature response to heating may be used to discriminate different layers within the air-snow-ice-ocean system.
The thermistor chain is usually installed in a standard hole produced by a 2-inch auger. A weight is attached to the bottom end to keep it straight. The data is returned after each sample using the Iridium SBD system. During the deployment, the manual measurements of snow thickness, ice draft and freeboard, and location of IMB sensors are usually made. The IMB deployment disturbs the system around sea ice. For example, snow may have poor contact with the thermistor chain. Additionally, the 2-inch hole may refreeze very slowly if the air temperatures are high or the snow is deep. In summer, the presence of the chain may lead to receiving additional solar energy absorption, which may influence the rates of snow and ice melt.
Usage in research
IMBs were used in several Arctic and Antarctic expeditions, including the SHEBA expedition in Beaufort Gyre, N-ICE2015 expedition north of Svalbard, and the MOSAiC expedition across Transpolar drift.
The usage of IMBs revealed that in the Central Arctic regions with high sea ice concentration, surface and bottom ice melt are comparable. In contrast, in regions with low sea ice concentration, the amount of ice bottom melt is substantially larger. IMBs can be also used to show spatial and temporal variability of sea ice growth and melt, also providing an estimate of ocean heat fluxes IMBs can also be used for studying pressure ridges for analysis of their winter consolidation rates, for analysis of ridge consolidation during their warming, and to study effects of snow slush contribution to the ridge consolidation. IMBs also allow the study of the temporal evolution of under-ice meltwater layers, conditions of false bottom formation, and their effect on ice melt rates.
References
Glaciology
Sea ice
Buoyage | Ice mass balance buoy | [
"Physics"
] | 845 | [
"Physical phenomena",
"Earth phenomena",
"Sea ice"
] |
74,378,082 | https://en.wikipedia.org/wiki/HD%2025274 | HD 25274, also known as HR 1241, is a solitary star located in the northern circumpolar constellation Camelopardalis. It is faintly visible to the naked eye as a red hued point of light with an apparent magnitude of 5.86. Gaia DR3 parallax measurements imply a distance of 597 light-years and it is currently drifting closer with a heliocentric radial velocity of . At its current distance, HD 25274's brightness is diminished by three-tenths of a magnitude due to interstellar extinction and it has an absolute magnitude of −0.51.
HD 25274 has a stellar classification of M0 III, indicating that it is an evolved red giant. However, the Bright Star Catalog gives a hotter classification of K2 III. The spectrophotometry-measured angular diameter, after correcting for limb darkening, is . At the estimated distance for HD 25274, this yields a physical radius 39.8 times that of the Sun. It also has an empirical radius of and Gaia DR3 models a larger radius. The object radiates 762 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of . HD 25274 is metal deficient with an iron abundance 62% that of the Sun's ([Fe/H] = −0.21) and it spins modestly with a projected rotational velocity of . HD 25274 is a field star of the HIP 21974 cluster.
References
M-type giants
Camelopardalis
BD+68 00303
025274
019129
1241 | HD 25274 | [
"Astronomy"
] | 339 | [
"Camelopardalis",
"Constellations"
] |
74,378,566 | https://en.wikipedia.org/wiki/Michael%20L.%20Perlis | Michael L. Perlis is an American clinical research scientist in insomnia and behavioral sleep medicine. He is Director of the Behavioral Sleep Medicine Program at the University of Pennsylvania, where he is also an associate professor of Psychiatry and Nursing.
Perlis has worked in the fields of behavioral sleep medicine and sleep research since 1984.
Education
Perlis received his bachelor's degree in religious studies from Guilford College, and his master's degree in Psychology and PhD in Clinical Psychology from the University of Arizona.
Career
Perlis is Director of the Behavioral Sleep Medicine Program at the University of Pennsylvania, where he is also an associate professor of Psychiatry and Nursing. He also serves on the Journal of Sleep Research, The Journal of Sleep Medicine Research, the journal of Behavioral Sleep Medicine, and the Journal of Health Psychology.
Perlis received The Peter Hauri Career Distinguished Achievement Award from the Society of Behavioral Sleep Medicine, and served as a founding and organizing member of the Society of Behavioral Sleep Medicine.
Research
Perlis has published over 200 peer-reviewed scientific articles on the etiology of and treatments for Chronic Insomnia. His contributions to the literature include establishing sleep disturbance as a causal factor in depression, establishing the antidepressant effects of Cognitive Behavioral Therapy for Insomnia, and evaluating the comparative efficacy of medication treatment and behavioral treatments for Insomnia.
Perlis is a co-author of the first textbook on Cognitive Behavioral Therapy for Insomnia, and has conducted training workshops on CBT-I for clinicians.
References
Sleep researchers
Year of birth missing (living people)
Living people
University of Arizona alumni
Guilford College alumni
University of Pennsylvania faculty
Place of birth missing (living people) | Michael L. Perlis | [
"Biology"
] | 337 | [
"Sleep researchers",
"Behavior",
"Sleep"
] |
74,379,021 | https://en.wikipedia.org/wiki/HD%2046509 | HD 46509, also designated as HR 2396, is a solitary star located in the northern circumpolar constellation Camelopardalis, the giraffe. It is faintly visible to the naked eye as a yellowish-orange hued point of light with an apparent magnitude of 5.86. The object is located relatively far at a distance of 791 light-years based on Gaia DR3 parallax measurements, but it is drifting closer with a heliocentric radial velocity of . At its current distance, HD 46509's brightness is diminished by interstellar extinction of 0.31 magnitudes and it has an absolute magnitude of −0.98.
HD 46509 has a stellar classification of either G9 III or K0 III, with both classes indicating that it is an evolved red giant. It is estimated to be 339 million years old, enough time for it to cool and expand to 27.3 times the radius of the Sun. HD 46509 has about 5.6 times the mass of the Sun and it radiates 399 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of . It is metal enriched with an iron abundance 132% that of the Sun's ([Fe/H] = +0.12) and like most giant stars, it spins slowly with a projected rotational velocity of approximately .
References
K-type giants
Camelopardalis
BD+71 00359
046509
031946
2396 | HD 46509 | [
"Astronomy"
] | 311 | [
"Camelopardalis",
"Constellations"
] |
74,380,261 | https://en.wikipedia.org/wiki/Selenocyanate | A selenocyanate is an ion or chemical compound that contains the -SeCN group, which could be in the form of an anion, SeCN−. Organic selenocyanates also exist.
Some complex ions with transition metals such as silver and mercury (mercuriselenocyanates) are known. Mercuriselenocyanate salts also include K, Fe, Co, Ni, Cu, Zn, and Cd. Complex ions include Fe(NCSe)63−, Fe(NCSe)64−, Fe(NCSe)42−, Co(NCSe)64−, Co(NCSe)42−, Ni(NCSe)64−, Zn(NCSe)64−, Rh(NCSe)64−, Pd(NCSe)42−, Ag(SeCN)2−, Cd(NCSe)42−, Cd(NCSe)64−, Dy(NCSe)63−, Ho(NCSe)63−, Er(NCSe)63−, Pt(NCSe)62−, Au(NCSe)4−, and Hg(NCSe)42−.
For hard metals, the negative charge is on the nitrogen atom which coordinates with the metal atom. Examples include Ti(NCSe)62−, V(NCSe)63−, VO(NCSe)42−, Cr(NCSe)63−, Mn(NCSe)42−, Mn(NCSe)42−, Y(NCSe)63−, Zr(NCSe)62−, Mo(NCSe)63−, Pr(NCSe)63−, Nd(NCSe)63−, Sm(NCSe)63−, Hf(NCSe)62−, Re2(NCSe)82−, Pa(NCSe)84− and U(NCSe)84−.
Production
Selenocyanate can be produced in the reaction of selenium, selenide, selenite or selenate with cyanide ions.
Se2− + CN− + 0.5 O2 → SeCN− + 2OH−
SeO32− + 3CN− → 2OCN− + SeCN− + 2OH−
SeO42− + 4CN− → 3OCN− + SeCN− + 2OH−
Reactions
Selenocyanate is oxidised to selenium and cyanate by bis (trifluoroacetoxy) iodobenzene.
Application
Selenocyanate is component of pollution from oil refineries and mine drainage water. Remediation methods have been investigated to extract selenocyanate from water. Methods considered include precipitation by metal salts, or extraction by plants. Indian mustard converts some selenocyanate to selenocystine and selenomethionine, and volatiles dimethylselenide and methylselenocyanate.
List
References | Selenocyanate | [
"Chemistry"
] | 622 | [
"Selenocyanates",
"Functional groups"
] |
74,380,428 | https://en.wikipedia.org/wiki/Teaching%20quantum%20mechanics | Quantum mechanics is a difficult subject to teach due to its counterintuitive nature. As the subject is now offered by advanced secondary schools, educators have applied scientific methodology to the process of teaching quantum mechanics, in order to identify common misconceptions and ways of improving students' understanding.
Common learning difficulties
Students' misconceptions range from fully classical physics thinking, mixed models, to quasi-quantum ideas. For example, if the concept that quantum mechanics does not describe a path for electrons or photons is misunderstood, students may believe that they follow specific trajectories (classical), or sinusoidal paths (mixes), or are simultaneously wave and particles (quasi-quantum: "in which students understand that quantum objects can behave as both particles and waves, but still have difficulty describing events in a nondeterministic way"). Among the concepts most often misunderstood are:
the postulates of quantum mechanics provide no description for the trajectories for electrons or photons,
amplitude of a wave is not a measure of energy,
most bound states have no corresponding classical orbits,
in practice, quantum mechanics gives probabilisitic rather than deterministic results,
intrinsic uncertainty rather than measurement error.
Issues also arise from misunderstanding classical concepts related to quantum concepts, such as the difference between light energy and light intensity.
Teaching strategies
Mathematics
Quantum mechanics can be taught with a focus on different interpretations, different models, or via mathematical techniques. Studies have shown that focus on non-mathematical concepts can lead to adequate understanding.
Digital and multi-media
Despite the fundamental impossibility of directly viewing quantum states, multimedia visualizations are an important tool in education.
Interactive media provides an alternative experience beyond everyday personal experience as a tool for understanding quantum mechanics. Among the multimedia sites that have been studied with positive results are QuVis and Phet.
History and philosophy of science as educational guides
In introducing history as part of the process of teaching quantum mechanics sets up a potential conflict of goals: accurate history or pedagogical clarity. Studies have shown that teaching through history helps students recognize that the counterintuitive issues are fundamental rather than simply something they don't understand. Specifically discussing the historical debates on quantum concepts drives home the idea the quantum differs from classical. Discussing the philosophy of science introduces the idea that language derived from everyday experience limits our ability to describe quantum phenomena.
Directly discussing the meanings of words
Mohan analyzes two widely used representative quantum mechanics textbooks against the learning challenges reported by Krijtenburg-Lewerissa and others. Both texts adopt language ('waves' and 'particles') familiar to students in other contexts without directly exploring the significant shifts in meaning required by quantum mechanics. Mohan attributes some of the learning challenges to this unexplored application of inappropriate language.
Teaching for quantum computing
N. David Mermin reports that an unconventional strategy based on abstract but simple math concepts is sufficient to teach quantum mechanics to students interested in quantum computing application rather than physics. Many of the issues that confound students of physics to not apply to this case and the mathematical background of quantum computing resembles the background already taught in computer science. Mermin develops notation and operations with classical bits then introduces quantum bits as superpositions of two classical states. He never needs to discuss even the Planck constant, which he suggests is important for quantum computer hardware but not software.
Teaching based on quantum optics
Philipp Blitzenbauer engages students through simple but intrinsically quantum single-photon experiments. The approach avoids the ambiguous classical vs quantum character of photons in optical interference experiments like the double slit. Students exposed to quantum mechanics in this way avoid developing misconceptions apparent among students in the control group.
See also
Physics education
Physics education research
Introduction to quantum mechanics
Mermin's device
List of textbooks about quantum mechanics
Notes
References
Quantum mechanics
Pedagogy | Teaching quantum mechanics | [
"Physics"
] | 775 | [
"Theoretical physics",
"Quantum mechanics"
] |
74,380,434 | https://en.wikipedia.org/wiki/Manfred%20Cuntz | Manfred Cuntz is a German astrophysicist based in the United States since 1988. He is a Distinguished Professor of physics at the University of Texas at Arlington (UTA). His primary research interests include stellar astrophysics, astrobiology, and planetary habitability. In 2023, he became a fellow with the Committee for Skeptical Inquiry.
Early life and education
Manfred Cuntz was born on April 21, 1958, in Landau in der Pfalz in Rhineland-Palatinate, Germany. He was the first-born son of Gerhard Hermann Cuntz and Irene Emma Cuntz (née Messerschmitt) and was raised in Bornheim. His family's business was in viticulture and livestock agriculture. As the eldest son, Cuntz would have inherited the farm. Early on, however, his family deemed him unsuitable for farm work and, instead, had him focus on his education.
Cuntz attended secondary school at the Eduard-Spranger Gymnasium in Landau, from which he graduated with the Abitur in 1977. Even though he was a dedicated student, especially in mathematics and the natural sciences, academic success did not come easily to Cuntz in all subjects. In fact, he had to repeat the eighth grade. After that, however, he became a top student, especially in the last years of secondary school when he was able to focus on the subjects of mathematics, chemistry, and social studies.
Cuntz went on to study physics and astronomy at the University of Heidelberg, Germany. There, he earned a Diplom (equivalent to having earned both a U.S. bachelor's and master's degrees) in Physics in 1985. He earned his PhD (Dr. rer. nat.) in Astronomy from the same university in 1988 with a dissertation on stellar atmospheric heating and stellar winds, titled Generation of Extended Chromospheres and Mass Loss of Late-Type Giant Stars due to Acoustic Shock Waves.
Career
After completing his degrees at the University of Heidelberg, Manfred Cuntz moved to the United States. He held positions as a postdoctoral research assistant in the Joint Institute for Laboratory Astrophysics (JILA) at the University of Colorado from 1989 to 1991 and at the High Altitude Observatory (HAO) from 1992 to 1993, a division of the National Center for Atmospheric Research (NCAR). In 1994, he returned to the University of Heidelberg as Habilitation Fellow. Then, he joined the Center for Space Plasma and Aeronomic Research at the University of Alabama in Huntsville from 1996 until 1999. In 2000, Cuntz became a visiting professor in the physics department of the University of Texas at Arlington, then moved up the tenure track to become Professor in 2012.
He is an editor of the journal Astronomische Nachrichten (Astronomical Notes).
Research
Cuntz's research focuses on the probability and possible distribution of extraterrestrial life on extrasolar planets and moons and "is based on a pure theoretical approach."
In 2000, Manfred Cuntz, together with Zdzislaw Musielak (UTA) and Steven Saar of the Harvard-Smithsonian Center for Astrophysics, made predictions "that planetary magnetic fields could produce detectable effects on stars". This phenomenon was later observed in 2003 by E. Shkolnik of the University of British Columbia, Canada. The underlying effect also allows to quantify magnetic fields in certain exoplanets. Cuntz also argued that "extreme magnetic protection by a powerful planetary magnetic dipole field" could increase the probability that a planet is habitable even if it is subject to "extreme ultraviolet and x-ray" radiation from its star.
In 2007, together with colleagues from the Potsdam Institute for Climate Impact Research (PIK), he arrived at the same conclusion as the group of F. Selsis (ENS Lyon), namely that the proposed exoplanet Gliese 581d, a super-Earth, is the first planet identified to be situated in a habitable zone outside the solar system. Since about 2014, based on new data, the existence of Gliese 581d has been disputed; however, the discussion on this is not yet complete.
In January 2012, Manfred Cuntz and Billy Quarles, as part of a team of researchers from the University of Texas Arlington, "gained international recognition for identifying the possibility of a habitable moon within the orbit of the recently discovered planet called Kepler-16b." The scientists used data from NASA's Kepler space telescope to analyze the possibilities of an Earth-like planet or moon to sustain life within the Kepler binary star system. They relied on Cuntz's expertise in astrobiology "to develop a range within the system where life would be able to exist." According to Cuntz, "the planet's critical feature to sustain life would be liquid water"; and he suggests those "life form[s] could be along the lines of a plant or bacteria."
Cuntz and Quarles collaborated again as co-authors on a study led by Oshina Jagtap published in 2021, which "explores the possibility of exomoons in a planetary system named HD 23079, located in Reticulum, a small constellation in the southern sky." This system is of interest because it contains a planet similar to Jupiter. Cuntz argues that since "Jupiter [is] a host to four planet-size moons (among many other moons), with two of them (Europa and Ganymede) having a significant chance of being habitable," gas giants in other star systems which could host an Earth-sized moon with the conditions for liquid water.
To assist astrophysicists in identifying habitable zones, Cuntz developed "BinHab, a new online tool that can be used to calculate the regions of binary systems favorable for life" in 2014. According to Cuntz, the program considers both "the amounts of stellar radiation, which provides a favorable planetary climate for life, and the gravitational influence of both stars on an existing planet." The interim dean of the UTA College of Science, James Grover, said this tool "holds enormous potential for those who study space in the search for life."
Cuntz has worked with other researchers to "examined both the damaging and the favourable effects of ultraviolet (UV) radiation from stars on DNA molecules" and how it could affect "potential carbon-based extraterrestrial life forms in the habitable zones around other stars." A study conducted by Cuntz, Satoko Sato, and researchers from the University of Guanajuato in Mexico found that F-type star systems "may [...] be a good place to look for habitable planets" because they have a larger "area where conditions are right for general Earth-type planets to develop and sustain life" than smaller, cooler stars like our Sun. The research demonstrated that the damage to DNA from UV radiation on planets "in the outer portions of F-star habitable zones" was "similar to the damage on Earth, if Earth did not have an atmosphere."
In 2016, Cuntz, while collaborating with Edward Guinan at Villanova University, explored which types of stars are best suited to offer prospects of habitability. They argued in favor of orange dwarfs, namely low-luminosity G-type and K-type stars; the related planetary condition is sometimes also called superhabitability. Guinan pointed out that "[m]any K-stars can be much older than our Sun. So, if life formed and evolved on habitable zone planet hosted by a[n] old K-star ... a few to several billions of years older than the Sun; it could maybe even harbor intelligent life."
In 2022, while collaborating with four of his students, Cuntz published a catalog of planet-hosting triple star systems, a relatively rare astronomical phenomenon.
Community involvement
Cuntz actively participates in education and public outreach (EPO). He has worked with The Planetarium at University of Texas at Arlington to create several shows. A 45-minute film titled Magnificent Sun, for which Cuntz co-authored the script, is intended to allow "the general public to share information and excitement about solar physics." Another show, Cosmic CSI: Looking for Life in the Universe, aims to present Cuntz's "research in astrobiology to the rest of the community." Additionally, he was the Principal Investigator for the development of a 3-D planetarium film "based on NASA's research and outreach mission, Stratospheric Observatory for Infrared Astronomy, or SOFIA."
Outside of his academic work, Cuntz pursues examination of fake news in science by writing articles in the journal Skeptical Inquirer. This has included articles about misguided criticism of the work of Albert Einstein
and commentary about responses from religious groups regarding the James Webb Space Telescope (JWST).
Literary influences
A publication by Cuntz on possible Earth-like planets in the star system 55 Cancri served as inspiration for Kenneth E. Ingle's science fiction novel First Contact: Escape to 55 Cancri.
Cuntz has also chosen to explore urban legends. He offered contributions to Rolf Wilhelm Brednich, at that time a professor of Folklore / European ethnology at the University of Göttingen in Germany, for one of his books on modern legends.
In 2024, Cuntz published his first kids book, titled Fun with Three Suns in the Sky, aimed at sparking interest in young children in astronomy and space science. The storyline of the book is loosely modeled after the Alpha Centauri system.
References
Publications
Books
Selected Articles
X-ray Activity Variations and Coronal Abundances of the Star-Planet Interaction Candidate HD 179949 (2023) (incl. A. Acharya, V. L. Kashyap, S. H. Saar, K. P. Singh).
An Early Catalog of Planet-Hosting Multiple-Star Systems of Order Three and Higher (2022) (incl. G. E. Luke, M. J. Millard, L. Boyle, S. D. Patel).
Updated Studies on Exomoons in the HD 23079 System (2021) (incl. O. Jagtap, B. Quarles).
Orbital Stability of Exomoons and Submoons with Applications to Kepler 1625b-I (2020) (incl. M. Rosario-Franco, B. Quarles, Z. E. Musielak).
Can Planets Exist in the Habitable Zone of 55 Cancri? (2019) (incl. S. Satyal).
Exocomets in the 47 UMa System: Theoretical Simulations Including Water Transport (2018) (incl. B. Loibnegger, R. Dvorak).
Case Studies of Exocomets in the System of HD 10180 (2017) (incl. B. Loibnegger, R. Dvorak).
About Exobiology: The Case for Dwarf K Stars (2016) (incl. E. F. Guinan).
Fractal and Multifractal Analysis of the Rise of Oxygen in Earth's Early Atmosphere (2015) (incl. S. Kumar, Z. E. Musielak).
Habitability of Earth-mass Planets and Moons in the Kepler-16 System (2012) (incl. B. Quarles, Z. E. Musielak).
The Advection of Supergranules by the Sun's Axisymmetric Flows (2010) (incl. D. H. Hathaway, P. E. Williams, K. Dela Rosa).
On the Reality of the Suggested Planet in the Nu Octantis System (2010) (incl. J. Eberle).
The Great Oxidation of Earth's Atmosphere: Contesting the Yoyo Model via Transition Stability Analysis (2009) (incl. D. Roy, Z. E. Musielak).
A Method for the Treatment of Supergranulation Advection by Giant Cells (2009) (incl. P. E. Williams).
Acoustic Heating of the Solar Chromosphere: Present Indeed and Locally Dominant (2007) (incl. W. Rammacher, Z. E. Musielak).
A New Version of Reimers' Law of Mass Loss Based on a Physical Approach (2005) (incl. K.-P. Schröder).
On the Possibility of Earth-type Habitable Planets in the 55 Cancri System (2003) (incl. W. von Bloh, C. Bounama, S. Franck).
Orbital Stability of Terrestrial Planets inside the Habitable Zones of Extrasolar Planetary Systems (2002) (incl. M. Noble, Z. E. Musielak).
On Stellar Activity Enhancement Due to Interactions with Extrasolar Giant Planets (2000) (incl. S. H. Saar, Z. E. Musielak).
A Generalized Version of the Rankine-Hugoniot Relations Including Ionization, Dissociation and Related Phenomena (1993) (incl. H. Nieuwenhuijzen, C. de Jager, A. Lobel, L. Achmad).
1958 births
German astronomers
20th-century German astronomers
21st-century German astronomers
German scientists
Astrophysicists
German astrophysicists
Living people
German science communicators
Space advocates
Heidelberg University alumni
University of Texas at Arlington faculty | Manfred Cuntz | [
"Physics"
] | 2,804 | [
"Astrophysicists",
"Astrophysics"
] |
71,370,706 | https://en.wikipedia.org/wiki/HP-505 | HP-505 is a triple reuptake inhibitor that was investigated by Hoechst-Roussel Pharmaceuticals. In mice, HP-505 was a potent inhibitor of tetrabenazine-induced ptosis which may indicate antidepressant activity.
Pharmacology
The inhibitory effect of HP-505 on serotonin reuptake is approximately 1.8 and 3.5 times stronger than on norepinephrine and dopamine, respectively. Subsequent investigations have found that HP-505 acts on presynaptic dopamine transporters and is devoid of anticholinergic effects.
Synthesis
The N-methylated analog is called HP-365 [59142-29-9].
An older synthesis is available, although more modern methods exist now:
References
Serotonin–norepinephrine–dopamine reuptake inhibitors
Drugs not assigned an ATC code
Piperidines
Isobenzofurans
Spiro compounds | HP-505 | [
"Chemistry"
] | 198 | [
"Organic compounds",
"Spiro compounds"
] |
71,371,320 | https://en.wikipedia.org/wiki/Leucocoprinus%20biornatus | Leucocoprinus biornatus is a species of mushroom producing fungus in the family Agaricaceae.
Taxonomy
It was first described in 1871 by the British mycologists Miles Joseph Berkeley & Christopher Edmund Broome who classified it as Agaricus biornatus.
In 1887 it was classified as Lepiota biornata by the Italian botanist and mycologist Pier Andrea Saccardo and then as Mastocephalus biornatus in 1891 by the German botanist Otto Kunze, however Kunze's Mastocephalus genus, along with most of '''Revisio generum plantarum was not widely accepted by the scientific community of the age so it remained a Lepiota.
In 1945 it was reclassified as Leucocoprinus biornatus by the French mycologist Marcel Locquin who also classified the subspecies Leucocoprinus badhamii subsp. biornatus in the same year. This is now considered a synonym.
Description
Leucocoprinus biornatus is a small dapperling mushroom with white flesh that may tinge yellow, pinkish or brown.Cap: 8–10 cm wide with brittle flesh. White and silky but discolouring pinkish with age. Conical when young expanding to convex or campanulate (bell shaped) and becoming irregularly shaped with age but with a persistent umbo throughout. It is covered in light brown woolly scales (floccose or squamulose) which become a darker brown or reddish with age. The cap edges are striated and start white but become pinkish and then brown when bruised or as it matures. Stem: 5–15 cm tall and 2-2.5 cm thick with a bulging centre (fusiform) and slightly bulbous base. White and silky on the outside with white internal flesh that begins solid but hollows with age. The membranous, ascending stem ring is white but bordered by brownish mottled edges. The base is scaly and discolours slightly yellow and then pink or brown with age or with damage. Gills: Free and crowded, swollen in the middle and whitish but turning yellowish with age. The edges are crenelated and tinged brown. Orange-brown or dark red-brown staining is visible when damaged. Spore print: Creamy white. Spores: Elliptical or globose. 10 x 8 μm. Smell: Unpleasantly pungent, acidic and noxious. Taste: Unpleasant flavour similar to that of Lepiota species.
When dry the stem and cap develop a pink or reddish colour.
Habitat and distribution
L. biornatus is scarcely recorded and little known. Berkeley and Broome only say that the specimens studied were found on the ground in Peradeniya, Sri Lanka (then known as Ceylon) in 1868. The majority of the observations documented in their paper (which provide a location) were made there so it is possible that they were in or around the vicinity of the Royal Botanical Gardens, Peradeniya, which were founded in 1843. In their introduction to 'On the Fungi of Ceylon''' it is remarked how closely the agarics documented resembled those of species found in Britain.
The specimens studied by Locquin were found growing in clusters (cespitose) or individually on soil in Lyon, France in September 1944.
In 1883 the English botanist and mycologist Mordecai Cubitt Cooke produced illustrations of Agaricus (Lepiota) biornatus in his book entitled 'Illustrations of British Fungi'. The mushrooms were described as growing in 'hot-beds and stoves. A stove or stovehouse was the common term used at the time to refer to a heated greenhouse, since they were often warmed via the exhaust flue of a wood stove to enable the growing of exotic tropical plants which could not otherwise survive the cold temperatures of Britain.
References
Leucocoprinus
Fungi described in 1871
Taxa named by Miles Joseph Berkeley
Taxa named by Christopher Edmund Broome
Fungus species | Leucocoprinus biornatus | [
"Biology"
] | 825 | [
"Fungi",
"Fungus species"
] |
71,372,243 | https://en.wikipedia.org/wiki/Josette%20Garnier | Josette Garnier is a French biogeochemist. She is research director at the French National Centre for Scientific Research (CNRS). She won the 2016 Ruth Patrick Award.
Life
She graduated from Pierre and Marie Curie University. She studied the price of land in the 1700s and the Riverstrahler model of river nutrient transfer.
Works
References
Year of birth missing (living people)
Living people
20th-century French women scientists
21st-century French women scientists
Geochemists
Pierre and Marie Curie University alumni
French biochemists
Research directors of the French National Centre for Scientific Research | Josette Garnier | [
"Chemistry"
] | 119 | [
"Geochemists"
] |
71,372,304 | https://en.wikipedia.org/wiki/Dream%20character | A dream character, sometimes abbreviated as DC, is an interactable human-like entity in the person's dream, especially while the person is REM-sleeping. The topic has been profoundly addressed in the lucid dreaming community, since while experiencing a lucid dream, the person can consciously interact with dream characters.
A specific dream character may reappear from dream to dream.
Capabilities
Dream characters may agree or disagree if asked to perform specific tasks. If they agree, they can solve tasks such as rhyming or drawing, although they have relatively poor arithmetical skills.
Furthermore, dream characters have the ability to come up with ways to outwit the dreamer, like switching off the light to avoid his or her gaze. Recurring dream characters can learn from previous dreams and adapt their behaviour accordingly.
Nature
The nature of dream characters is subject to debate amongst dream researchers. Some psychotherapists suggest that they represent parts of the dreamer's self.
The hypothesis that dream characters may have a consciousness of their own has been brought forth by some researchers, such as Paul Tholey. Although this hypothesis is impossible to prove, experiments have shown them to have capabilities which suggest that they may have independent points of view and behave like conscious beings.
References
Character | Dream character | [
"Biology"
] | 253 | [
"Dream",
"Behavior",
"Sleep"
] |
71,373,183 | https://en.wikipedia.org/wiki/Waitea%20zeae | Waitea zeae is a species of fungus in the family Corticiaceae. Basidiocarps (fruit bodies) are corticioid, thin, effused, and web-like, but the fungus is more frequently encountered in its similar but sterile anamorphic state. Waitea zeae is best known as a plant pathogen, causing commercially significant damage to cereals, grasses, and a wide range of other plants.
Taxonomy
Rhizoctonia zeae was originally described from Florida in 1934. It was later considered to be the anamorph (asexual state) of Waitea circinata. Molecular research has, however, shown that Waitea circinata is part of a complex of at least four genetically distinct taxa, each causing visibly different diseases. These taxa were initially treated (invalidly) as varieties of W. circinata, but have now been described as separate species.
References
External links
Index Fungorum
USDA ARS Fungal Database
Fungal plant pathogens and diseases
Corticiales
Fungi described in 1934
Fungi of North America
Fungus species | Waitea zeae | [
"Biology"
] | 225 | [
"Fungi",
"Fungus species"
] |
71,374,196 | https://en.wikipedia.org/wiki/Phacopsis%20thallicola | Phacopsis thallicola is a species of lichenicolous (lichen-dwelling) fungus in the family Parmeliaceae. It was first formally described as a new species in 1852 by Italian botanist Abramo Bartolommeo Massalongo, as Lecidea thallicola. The type specimen, collected from the province of Treviso in Italy, was growing on the foliose lichen Parmelia caperata (now known as Flavoparmelia caperata). Dagmar Triebel and Gerhard Walter Rambold transferred the taxon to the genus Phacopsis in 1988. The known generic hosts of Phacopsis thallicola are all in the Parmeliaceae: Parmotrema, Cetrelia, Flavopunctelia, and Hypotrachyna.
Some historical synonyms of Phacopsis thallicola have resulted from proposed taxonomic transfers from its original genus Lecidea to the genera Scutula, Mycoblastus, and Nesolechia. Abrothallus curreyi, first reported by William Lauder Lindsay from New Zealand in 1866, is a synonym of Phacopsis thallicola.
Characteristics of Phacopsis thallicola include its dark-brown hypothecium (the area of tissue in the apothecium immediately below the subhymenium), and the mostly sessile, marginate apothecia. Its ascospores are typically 8–11 by 5–6.5 μm. Its pycnidia are spherical and measure about 120 μm; they are immersed in the thallus of the host. Pycnospores have a bacilliform shape and dimensions of 7 by 1 μm. The fungus has been recorded from Italy, Java, New Zealand (as Abrothallus curreyi), and the United States.
References
Parmeliaceae
Fungi described in 1852
Lichenicolous fungi
Fungi of Asia
Fungi of Europe
Fungi of New Zealand
Fungi of the United States
Taxa named by Abramo Bartolommeo Massalongo
Fungus species | Phacopsis thallicola | [
"Biology"
] | 435 | [
"Fungi",
"Fungus species"
] |
71,376,194 | https://en.wikipedia.org/wiki/Leucocoprinus%20acutoumbonatus | Leucocoprinus acutoumbonatus is a species of mushroom producing fungus in the family Agaricaceae.
Taxonomy
It was first described in 2009 by the Indian mycologists T.K. Arun Kumar & Patinjareveettil Manimohan who classified it as Leucocoprinus acutoumbonatus.
Description
Leucocoprinus acutoumbonatus is a small dapperling mushroom with thin (under 2mm thick) whitish flesh.
Cap: 2-6cm wide with a convex to campanulate (bell shaped) cap when young, expanding to convex, broadly convex and finally conico-campanulate usually with a prominent conical umbo which becomes more pronounced with age. The cap is mostly dull white with yellowish white tones coming through at the cap edges and a brown umbo with woolly (floccose) scales occurring more towards the centre. Striations (sulcate-striate) are present towards the cap edge, which curves inwards when young but straightens as it ages and may develop serrations. Gills: Free and close to crowded at up to 10mm wide, white but discolouring yellowish brown with age. The gill edges are serrated (fimbriate to denticulate). Stem: 3-5.5 cm tall and 3-5mm thick, tapering slightly from the wider base that is up to 10mm and may be surrounded with white mycelium. The outside of the stem is white with a reddish grey tint which discolours greyish brown in age or red to brownish orange when bruised. It has a powdery or silky texture on the outside and the internal flesh is solid when young but becomes fistulose or hollow with age. The membranous, fixed stem ring is located high up the stem (superior) and has dark brown scales (squamules) on the top. The stem flesh discolours to a reddish colour on exposure to air. Spore print: White. Spores: Ovoid or ellipsoid with a truncated base and a germ pore. Dextrinoid. 8-11 x 6-8 μm. Smell: Indistinct.
Etymology
The specific epithet acutoumbonatus is Latin for 'with an acute umbo'.
Habitat and distribution
L. acutoumbonatus is scarcely recorded and little known and may be confused with numerous other red staining Leucocoprinus or Leucoagaricus species. The specimens studied were growing individually or in tufts (caespitose) on the bark of live trees or on rotting wood in the state of Kerala, India.
References
Leucocoprinus
Fungi described in 2009
Fungus species | Leucocoprinus acutoumbonatus | [
"Biology"
] | 562 | [
"Fungi",
"Fungus species"
] |
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