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67,319,811 | https://en.wikipedia.org/wiki/Dai%20Games | David Edgar Games (1938 – 28 May 2018) was a Welsh chemist best known for his work in mass spectrometry and chromatography.
Early life and education
Dai grew up in Ynysddu in South Wales and attended the Lewis School, Pengam.
Career and research
Dai graduated from King's College London, where he also obtained his PhD. After postdoctoral work at McMaster University, Hamilton, he moved to University of Wales Cardiff, where he progressed to a personal chair. In 1989 he moved to Swansea as Head of the Mass Spectrometry Research Unit at University of Wales, Swansea. Although best known as a mass spectrometrist and separation scientist who was the first person to bring liquid chromatography-mass spectrometry to Europe, he has made considerable contributions in organic chemistry research and served as Head of the Chemistry Department at Swansea.
Awards and honours
In 1987, he was awarded the Royal Society of Chemistry medal for Analytical Separations and in 1991, was awarded the Martin Medal by the Chromatographic Society. In 1993 he received the Gold Medal of the Society of Analytical Chemistry. The International Mass Spectrometry Society awarded him the J.J.Thomson Medal in 1997, and in 1999 he received the A.J.Evans Medal from Cardiff University.
He was a past Chairman of the BMSS, served on the SERC Chemistry Committee as Chairman of the Instrumentation Panel and also on NERC, MRC and AFRC panels. He was a former Joint Editor-in-Chief of Biomedical and Environmental Mass Spectrometry.
References
1938 births
2018 deaths
Welsh chemists
Mass spectrometrists
Alumni of King's College London | Dai Games | [
"Physics",
"Chemistry"
] | 344 | [
"Biochemists",
"Mass spectrometry",
"Spectrum (physical sciences)",
"Mass spectrometrists"
] |
67,321,086 | https://en.wikipedia.org/wiki/Contrastive%20Hebbian%20learning | Contrastive Hebbian learning is a biologically plausible form of Hebbian learning.
It is based on the contrastive divergence algorithm, which has been used to train a variety of energy-based latent variable models.
In 2003, contrastive Hebbian learning was shown to be equivalent in power to the backpropagation algorithms commonly used in machine learning.
See also
Oja's rule
Generalized Hebbian algorithm
References
Hebbian theory
Artificial neural networks | Contrastive Hebbian learning | [
"Technology"
] | 97 | [
"Computing stubs"
] |
67,321,416 | https://en.wikipedia.org/wiki/Besicovitch%20inequality | In mathematics, the Besicovitch inequality is a geometric inequality relating volume of a set and distances between certain subsets of its boundary. The inequality was first formulated by Abram Besicovitch.
Consider the n-dimensional cube with a Riemannian metric . Let
denote the distance between opposite faces of the cube. The Besicovitch inequality asserts that
The inequality can be generalized in the following way. Given an n-dimensional Riemannian manifold M with connected boundary and a smooth map , such that the restriction of f to the boundary of M is a degree 1 map onto , define
Then .
The Besicovitch inequality was used to prove systolic inequalities
on surfaces.
Notes
References
Burago, Dmitri & Burago, Yuri & Ivanov, Sergei. (2001). A Course in Metric Geometry. Graduate Studies in Mathematics 33.
Burago Yu. & Zalgaller, V. A. Geometric inequalities. Grundlehren der Mathematischen Wissenschaften [Fundamental Principles of Mathematical Sciences], 285. Springer Series in Soviet Mathematics. Springer-Verlag, Berlin, 1988.
Misha Gromov. Metric structures for Riemannian and non-Riemannian spaces. Based on the 1981 French original. With appendices by M. Katz, P. Pansu and S. Semmes. Translated from the French by Sean Michael Bates. Progress in Mathematics, 152. Birkhäuser Boston, Inc., Boston, MA, 1999. xx+585 pp. .
Burago, D., & Ivanov, S. (2002). On Asymptotic Volume of Finsler Tori, Minimal Surfaces in Normed Spaces, and Symplectic Filling Volume. Annals of Mathematics, 156(3), second series, 891-914. doi:10.2307/3597285
Geometric inequalities | Besicovitch inequality | [
"Mathematics"
] | 396 | [
"Geometric inequalities",
"Inequalities (mathematics)",
"Theorems in geometry"
] |
67,321,510 | https://en.wikipedia.org/wiki/Nivaflex | Nivaflex is an octavariant alloy important in watchmaking, used primarily for the mainspring. The name was registered as a trademark in 1957 by Reinhard Straumann, a Swiss metallurgist. Nivaflex is "wholly non-magnetic" and displays a very low coefficient of thermal expansion. Its composition is of 45% cobalt, 21% nickel, 18% chromium, 5% iron, 4% tungsten, 4% molybdenum, 1% titanium and 0.2% beryllium; carbon content is less than 0.1 percent of the alloy's weight.
References
Horology
Timekeeping components
Springs (mechanical)
Cobalt alloys
Nickel alloys
Ferroalloys
Chromium alloys
Tungsten alloys
Molybdenum alloys
Titanium alloys
Beryllium alloys
Antiferromagnetic alloys | Nivaflex | [
"Physics",
"Chemistry",
"Technology"
] | 178 | [
"Nickel alloys",
"Titanium alloys",
"Components",
"Physical quantities",
"Horology",
"Time",
"Molybdenum alloys",
"Tungsten alloys",
"Alloys",
"Timekeeping components",
"Antiferromagnetic alloys",
"Spacetime",
"Beryllium alloys",
"Chromium alloys",
"Cobalt alloys"
] |
67,322,380 | https://en.wikipedia.org/wiki/Marine%20Carpuat | Marine Carpuat is a computer scientist who works on machine translation and natural language processing. She is known for her research connecting cross-lingual semantics with machine translation. She has been recognized with
a NSF Career Award in 2018, a Google Research award in 2016, and Amazon Faculty Awards in 2016 and 2018.
Education
Marine Carpuat obtained her MPhil and PhD from Hong Kong University of Science and Technology in 2008 under the supervision of Dekai Wu. Her PhD thesis was on the topic of machine translation, and demonstrated the first results showing that explicit modeling of lexical semantics could improve the accuracy of a machine translation system.
Career
After completing her education, Carpuat worked at the National Research Council Canada as a researcher.
In 2015, she joined University of Maryland as an assistant professor in Computer Science where she is a member of the CLIP lab. Carpuat works in the area of natural language processing with a focus on machine translation and cross-lingual semantics. She has published over 100 peer-reviewed research papers.
Her work is published in the proceedings of computer science conferences, including the Annual Meeting of the Association for Computational Linguistics and Empirical Methods in Natural Language Processing.
Selected honors and distinctions
2016 Google Research Award
2016, 2018 Amazon Research Awards
2018 NSF Career Award
References
External links
Living people
Computer scientists
Natural language processing researchers
Women computer scientists
Year of birth missing (living people) | Marine Carpuat | [
"Technology"
] | 279 | [
"Computer science",
"Computer scientists"
] |
67,322,896 | https://en.wikipedia.org/wiki/Azoamicus%20ciliaticola | "Candidatus Azoamicus ciliaticola" is a candidate species of endosymbiotic bacteria belonging to the eub62A3 group of Gammaproteobacteria, characterized for its capacity to perform denitrification within its ciliate host in anaerobic water environments. It was isolated from Lake Zug in Switzerland and described in 2021.
Ecology
"Ca. A. ciliaticola" is an obligate endosymbiont of an anaerobic freshwater ciliate from the class Plagiopylea. Endosymbiont contains highly reduced genome with 0.29 Mbp while substantial fraction of this genome is dedicated to energy production. "Ca. A. ciliaticola" contains complete gene set for denitrification and is thus the first observed obligate endosymbiont with such pathway.
Extensive genetic potential for energy metabolism hints that the main function of an endosymbiont is to generate ATP and provide it to its ciliate host. Ca. A. ciliaticola thus have functions which are similar to mitochondria, although it is not derived from a mitochondrial line of descent.
It provokes question if also some other eukaryota are using Prokaryotes to transfer electrons to non-canonical electron acceptors such as in the case of denitrification.
Other links
Nature podcast
A microbial marriage reminiscent of mitochondrial evolution
References
Gammaproteobacteria
Ciliates
Anaerobic respiration
Anaerobes
2021 in science | Azoamicus ciliaticola | [
"Biology"
] | 319 | [
"Bacteria",
"Anaerobes"
] |
67,322,960 | https://en.wikipedia.org/wiki/Nita%20Patel | Nita K. Patel (born 1965) is an Indian-American vaccinologist who leads vaccine development at Novavax. She oversaw the development of the Novavax COVID-19 vaccine.
Early life and education
Patel was born in Sojitra, a farming village in Gujarat. When she was four years old her father contracted tuberculosis, and came close to death. This experience motivated Patel to become a physician and attempt to find a cure for tuberculosis. She went on to earn a master's degree in microbiology at Sardar Patel University and a master's degree in biotechnology at Johns Hopkins University.
Research and career
After graduating from Johns Hopkins, Patel moved to Gaithersburg, Maryland where she worked for MedImmune, a company that looked to create vaccinations for tuberculosis, respiratory syncytial virus and Lyme disease. She was the sixteenth member of the MedImmune team. Later the company eventually acquired by AstraZeneca.
In 2015, Patel left AstraZeneca to join Novavax, a biotechnology start-up in Maryland. Her research considers antibody discovery and vaccine development. She oversaw the development of the Novavax COVID-19 vaccine, and led an all-woman team. After Patel received the SARS-CoV-2 spike protein in February 2020, she designed and characterized over twenty variants of the protein. This involved identifying the locations where antibodies bind to the protein, and developing tests to check whether the spike is consistent between manufacturing plant. The vaccines developed by Patel and Novavax make use of recombinant DNA. In an interview with Science Magazine, Patel said that she had worked eighteen hour days to develop the vaccine, but didn't get tired. They were awarded a $1.6 billion contract to run clinical trials. In 2021, the vaccine was shown to be 89% effective in large trials in the United Kingdom.
Selected publications
Personal life
Patel is married to an American biochemist.
References
1965 births
Living people
American people of Indian descent
Vaccinologists
People from Gujarat
Johns Hopkins University alumni
21st-century American women scientists
Women biotechnologists
American biotechnologists | Nita Patel | [
"Biology"
] | 441 | [
"Biotechnologists",
"Vaccination",
"Vaccinologists",
"Women biotechnologists"
] |
67,325,019 | https://en.wikipedia.org/wiki/Andrei%20Gritsan | Andrei V. Gritsan is an American-Siberian particle physicist. He was a member of a team of researchers at the Large Hadron Collider, who, in 2012, announced the discovery of a new subatomic particle, a Higgs boson.
Early life and education
Gritsan was born in Russia and graduated from Novosibirsk State University with his Bachelor of Science degree and master's degree in physics. He then enrolled at the University of Colorado, Boulder in the United States for his PhD.
Career
Gritsan joined the faculty at Johns Hopkins University in 2005 after working at the Lawrence Berkeley National Laboratory. As an assistant professor in the department of physics and astronomy, Gritsan won both the National Science Foundation's Faculty Early Career Development Award and a Sloan Research Fellowship in 2007. A few years later, he worked alongside more than 2,000 other scientists and researchers on the Higgs boson which was the recipient of a Nobel Prize in Physics.
In recognition of his "significant contributions to the discovery and to the characterization of the Higgs Boson at the CERN Large Hadron Collider, and for significant contributions to the measurement of sin2alpha at the SLAC PEP II collider," Gritsan was elected a Fellow of the American Physical Society.
References
External links
Living people
Year of birth missing (living people)
Novosibirsk State University alumni
University of Colorado Boulder alumni
Johns Hopkins University faculty
Fellows of the American Physical Society
21st-century American physicists
Particle physicists
People associated with CERN | Andrei Gritsan | [
"Physics"
] | 311 | [
"Particle physicists",
"Particle physics"
] |
67,326,725 | https://en.wikipedia.org/wiki/Zolt%C3%A1n%20Spakovszky | Zoltán S. Spakovszky is an aerospace engineer, academic and researcher. He is best known for his work on fluid system instabilities and internal flow in turbomachinery. He is T. Wilson (1953) Professor in Aeronautics at the Massachusetts Institute of Technology, and the Director of the MIT Gas Turbine Laboratory.
Education
Spakovszky received his Diplom Ingenieur degree in Mechanical Engineering from the Swiss Federal Institute of Technology (ETH Zurich) in 1997. He then moved to United States and earned his Master's and Doctoral Degree in Aeronautics and Astronautics from Massachusetts Institute of Technology in 1999 and 2001, respectively.
Career
Following his doctoral studies, Spakovszky joined the Department of Aeronautics and Astronautics at MIT as professorial faculty in 2001. He became the Director of the MIT Gas Turbine Laboratory in 2008.
Spakovszky's research focuses on solving complex, real world, high relevance technological issues related to aeroengines, power and propulsion systems. He has conducted work in compressor aerodynamics, aeroengine instabilities, rotordynamics, thermodynamics, aero-acoustics, propulsion and energy conversion, and aircraft design for environment. He investigated and explained the mechanisms of flow instabilities leading to in-flight aeroengine shutdowns. The results helped improve an engine diagnostic and health monitoring test employed by airlines for fleet management purposes and required by an FAA airworthiness directive. Spakovszky worked as chief engineer on the Silent Aircraft Initiative, a joint project between the University of Cambridge, MIT, and industry partners, that took step beyond aviation industry's noise reduction goals by delivering a credible conceptual aircraft design inaudible on take-off and landing. He also led a team to develop ultra high-speed gas bearings that enabled operation of multi-wafer rotating MEMS machines for power and propulsion applications at micro scale.
Spakovszky is a Fellow of American Society of Mechanical Engineers (ASME), an Associate Fellow of American Institute of Aeronautics and Astronautics (AIAA), and the Leader of the ASME Gas Turbine Segment Leadership Team,
Awards and honors
1997 - Georg Fischer Award, ETH Zurich
2003 - NASA Group Achievement Award
2003 - ASME Melville Medal
2009 - Ruth and Joel Spira Award for Excellence in Teaching, Massachusetts Institute of Technology
2012 - ASME Gas Turbine Award, International Gas Turbine Institute
2016 - ASME John P. Davis Gas Turbine Applications Award
2021 - ASME Scholar Award
Bibliography
Z. Spakovszky, “Analysis of Aerodynamically Induced Whirling Forces in Axial Flow Compressors”. ASME Journal of Turbomachinery 122, pp. 761 – 768, October 2000.
Z. Spakovszky "Backward Traveling Rotating Stall Waves in Centrifugal Compressors". ASME Journal of Turbomachinery 126.1 (2004): 1. January 2004.
Z. Spakovszky, “Stamp of Authenticity”, Mechanical Engineering 128, pp. 8, April 2006.
V. Lei, Z. Spakovszky, E. Greitzer "A Criterion for Axial Compressor Hub-Corner Stall" Journal of Turbomachinery 130.3 (2008): 031006. January 2008.
Z. Spakovszky, C. Roduner "Spike and Modal Stall Inception in an Advanced Turbocharger Centrifugal Compressor" Journal of Turbomachinery 131.3 (2009): 031012. January 2009
Z. Spakovszky, “High-Speed Gas Bearings for Mirco-Turbomachinery “, in Multi-Wafer Rotating MEMS Machines, Lang, J., ed., Springer, MEMS Reference Shelf Series, January 2009.
A. Peters, Z. Spakovszky, W. Lord, B. Rose "Ultrashort Nacelles for Low Fan Pressure Ratio Propulsors" Journal of Turbomachinery [0889504X] 137.2 (2014): 021001. September 2014.
G. Pullan, A. Young, I. Day, E. Greitzer, Z. Spakovszky "Origins and Structure of Spike-Type Rotating Stall" Journal of Turbomachinery [0889504X] 137.5 (2015): 051007. May 2015.
N. Shah, G. Pfeiffer, R. Davis, T. Hartley, Z. Spakovszky, Full-Scale Turbofan Demonstration of a Deployable Engine Air-Brake for Drag Management Applications," J. Eng. Gas Turbines Power. 2017; 139(11):111202-111202-13. August 2017.
C. Lettieri, D. Paxson, Z. Spakovszky, P. Bryanston-Cross "Characterization of Nonequilibrium Condensation of Supercritical Carbon Dioxide in a de Laval Nozzle" Journal of Engineering for Gas Turbines and Power, 140.4 (2018): 041701, April 2018
A. Kiss, Z. Spakovszky, “Effects of Transient Heat Transfer on Compressor Stability”, ASME J. Turbomach. 2018; 140(12):121003-121003-9. December 2018.
Z. Spakovszky, "Advanced Low-Noise Aircraft Configurations and Their Assessment: Past, Present, and Future", CEAS Aeronautical Journal, Volume: 10, Issue Number: 1, April 2019.
References
Living people
1972 births
Aerospace engineers
Massachusetts Institute of Technology alumni
ETH Zurich alumni | Zoltán Spakovszky | [
"Engineering"
] | 1,145 | [
"Aerospace engineers",
"Aerospace engineering"
] |
67,327,667 | https://en.wikipedia.org/wiki/2-Methylpentamethylenediamine | 2-Methylpentamethylenediamine is an organic compound part of the amine family with the formula H2NCH2CH2CH2CH(CH3)CCH2NCH2. A colorless liquid, this diamine is obtained by the hydrogenation of 2-methylglutaronitrile. It is better known by the trade name "Dytek A".
Uses
2-Methylpentamethylenediamine can serve as a curing agent for epoxy resin systems. It gives good adhesion to metals and resistance against corrosion and other chemicals. It provides toughness, low blush, uniform finish, high gloss, and improves UV stability. It reduces gel time and is compatible with epoxy resins. It is suitable for marine, industrial, and decorative coatings.
2-Methylpentamethylenediamine can also be used as a chain extender for polyurethane applications, and in particular with PUDs. Its derivatives like aspartic esters, secondary amines, aldimines and ketoimines serve as curatives in polyurea systems. In polyamides, 2-Methylpentamethylenediamine acts as a crystallinity disruptor. This makes polymers amorphous in structure and slows down crystallization. It lowers melting point, improves surface appearance, increases abrasion resistance, and dye uptake. It also reduces water absorption, gelling, melt and quench temperatures.
In summary, its uses are:
Corrosion inhibitor
Polyamide adhesive and ink resins.
Polyamide films, plastics, and fibers
Epoxy curing agents
Metalworking Fluids
Chain extenders
Water treatment chemicals
Isocyanates
Hazards
2-Methylpentamethylenediamine has many uses, but is a hazardous chemical. It can cause burns, is corrosive to skin, harmful when swallowed, and it can cause pulmonary edema and acute pneumonitis when inhaled in high concentrations.
See also
1,2-Diaminocyclohexane
Hexamethylenediamine
References
External links
http://www.chemspider.com/Chemical-Structure.77450.html
https://webbook.nist.gov/cgi/cbook.cgi?ID=15520-10-2
Amines | 2-Methylpentamethylenediamine | [
"Chemistry"
] | 490 | [
"Amines",
"Bases (chemistry)",
"Functional groups"
] |
67,329,814 | https://en.wikipedia.org/wiki/Y.3173 | Y.3173 is an ITU-T Recommendation building upon Y.3172 specifying a framework for evaluation intelligence levels of future networks such as 5G (IMT-2020). This includes:
Development trend of network intelligence
Methods for evaluating network intelligence levels
Architectural view for evaluating network intelligence levels
The standard addresses issue in Operation, Administration and Maintenance (OAM) of IMT-2020 networks such as:
diversified network deployment scenarios are
diversified terminals, such as in Internet of things (IoT)
manual decision-making mechanisms
mechanisms analysing large amounts of network
network connectivity among UEs
decoupling of software from the hardware in networks
transition towards a service-based intelligent network
Network intelligence is defined as:
Level of application of automation capabilities including those enabled by the integration of artificial intelligence techniques in the network.
References
External links
ITU-T Recommendation Y.3173
ITU-T Y Series Recommendations
ITU-T recommendations | Y.3173 | [
"Technology"
] | 189 | [
"Computing stubs",
"Computer network stubs"
] |
56,034,320 | https://en.wikipedia.org/wiki/Comparison%20of%20MQTT%20implementations | MQTT is an ISO standard (ISO/IEC PRF 20922) publish–subscribe-based messaging protocol. It works on top of the Internet protocol suite TCP/IP. It is designed for connections with remote locations where a "small code footprint" is required or the network bandwidth is limited. The publish-subscribe messaging pattern requires a message broker.
All comparison categories use the stable version of each implementation listed in the overview section. The comparison is limited to features that relate to the MQTT protocol.
Overview
The following table lists MQTT both libraries and implementations, along with general information about each.
A more complete list of MQTT implementations can be found on GitHub.
Protocol support
There are several versions of the MQTT protocol currently standardized. Below is a list containing the more recent versions of the MQTT protocol, with the organization that standardized them.
MQTT-SN v1.2, standardized by IBM.
MQTT v3.1, standardized by Eurotech and IBM.
MQTT v3.1.1, standardized by OASIS.
MQTT v5.0, standardized by OASIS.
The following table lists the versions of MQTT that each implementation supports, and also lists their support for SSL/TLS and TCP. The security provided by SSL/TLS may be desirable depending on the type traffic being sent between devices, as MQTT transmits messages in the clear.
Quality of service levels offered
From the MQTT page, quality of service (QoS) is described as,Quality of service refers to traffic prioritization and resource reservation control mechanisms rather than the achieved service quality. Quality of service is the ability to provide different priority to different applications, users, or data flows, or to guarantee a certain level of performance to a data flow.A description of each QoS level is found below.
At most one delivery (fire and forget)
At least one delivery (acknowledged delivery)
Exactly one delivery (assured delivery)
The following table lists each implementation's support of the QoS levels.
Portability concerns
Portability concerns in this section refers to technical details that may be deciding factors in selecting an implementation to use. In general, this table should be used by those with more knowledge about the device they will be using.
General requirements
The following table shows various requirements that may be useful when deciding on which implementation to use for a device.
References
Data transmission
MQ
Network protocols
Telemetry
Time series software
Application layer protocols
Message-oriented middleware
Software comparisons | Comparison of MQTT implementations | [
"Technology"
] | 521 | [
"Software comparisons",
"Computing comparisons"
] |
56,034,825 | https://en.wikipedia.org/wiki/C8H18S | {{DISPLAYTITLE:C8H18S}}
The molecular formula C8H18S (molar mass: 146.29 g/mol, exact mass: 146.1129 u) may refer to:
2-Methyl-2-heptanethiol
1-Octanethiol, or 1-mercaptooctane
n-Octyl mercaptan or Octyl mercaptan
Molecular formulas | C8H18S | [
"Physics",
"Chemistry"
] | 91 | [
"Molecules",
"Set index articles on molecular formulas",
"Isomerism",
"Molecular formulas",
"Matter"
] |
56,035,044 | https://en.wikipedia.org/wiki/Barbara%20Paulson | Barbara Jean Paulson (née Lewis; April 11, 1928 – February 26, 2023) was an American human computer at NASA's Jet Propulsion Laboratory (JPL) and one of the first female scientists employed there. Paulson began working as a mathematician at JPL in 1948, where she calculated rocket trajectories by hand. She is among the women who made early progress at JPL.
Early life
Barbara Jean Lewis was born in Columbus, Ohio on April 11, 1928. She was raised with three siblings
(two older sisters and one younger brother), and when she was 12 years old her father died. Beginning in 9th grade, Paulson took four years of Latin and math while her sisters took short hand as Paulson did not want to be a secretary. After attending Ohio State University for one year, Paulson's sister, who was already working in Pasadena at the time, convinced her mother to move to Pasadena as well. In 1947 the family moved to Pasadena, California, where her career at JPL would begin.
In 1959, Barbara married Harry Murray Paulson in Pasadena, where they lived until 1962 before moving to Monrovia. In 1975, they finally settled in Glendora.
Career
Paulson joined the Jet Propulsion Laboratory in 1948 as a computer, calculating rocket paths and working on the MGM-5 Corporal, the first guided missile designed by the United States to carry a nuclear warhead. Paulson and her colleagues were at one point invited to sign their names on the 100th Corporal rocket prior to its transport to the White Sands test range. The rocket exploded shortly after liftoff. On January 31, 1958, Paulson was assigned to the operations center for Explorer-1, the first satellite of the United States, launched during the Space Race with the Soviet Union. Paulson did the work with minimal equipment: a mechanical pencil, light table, and graph paper. The multi-stage launch that Paulson aided in calculations for allowed the Corporal to carry a warhead over 200 miles.
In 1960, when Paulson was 32 years old, she and her husband Harry were expecting their first child. When Paulson requested a closer parking space at work because she was pregnant, she was forced to quit as JPL did not employ pregnant women at the time and keeping a pregnant woman on staff would result in insurance policy problems. JPL had no maternity leave, so women who were fired or forced to quit their positions did not have jobs to return to after giving birth. Paulson's supervisor, Helen Ling, worked hard to rehire women who had been forced out with no parental leave, so in 1961, when her daughter was seven months old, Paulson accepted Ling's offer and returned to the lab. Paulson notably did not apply for a better parking spot when she got pregnant for the second time. At one point during Paulson's early years at JPL a beauty contest was held amongst the other female human computers. Paulson came in third place, and the queen of the contest was called 'Miss Guided Missile'.
In the 1960s, with JPL's reputation cemented by the success of Explorer-1, JPL began to set its sights on the moon and other interplanetary exploration missions. Paulson and her colleague Helen Ling worked overtime to calculate the trajectories of the Mariner probes that would later be sent to Venus and Mars. Paulson and her colleagues determined that only brief timeframes and launch opportunities existed that allowed for the ideal transit from Earth to its target. In the late 1960s, Paulson was given the title of engineer and eventually became a supervisor in the lab.
In the 1970s, Paulson later went on to play a vital role in the Viking program, becoming the first lander to reach the surface of Mars. Paulson successfully calculated the trajectory the Viking probe needed on its 11-month transit between Earth and Mars. Paulson's calculations also proved to be essential during the entry, descent, and landing (EDL) phase of the mission, in which the lander would detach from the spacecraft, enter the martian atmosphere, and parachute down to the surface. In the late 1970s, Paulson and her colleagues worked on some of the first interstellar trajectories during the planning of the Voyager missions, in which Voyager 1, having launched in September 1977, and as of April 13, 2019, is the most distant from Earth of all human-made objects.
Paulson retired from JPL in 1993 and remained in Pasadena until 2003 before moving to Iowa.
Personal life
Paulson and her husband Harry had daughters Karen (née Paulson) Bishop and Kathleen (née Paulson) Knutson, four grandchildren (Jonathan, Kyle, Harrison, and Corrine), and several nieces and nephews. Throughout pregnancy and her eventual return to work at JPL, Barbara's husband at the time was a real estate appraiser and member of the Pasadena Board of Realtors. Fortunately, upon Barbara's return to work, Harry was able to adjust his schedule, as did many of the other human computers with children, to ensure that their children were taken care of.
Barbara Paulson's husband, Harry Murray Paulson, died on July 9, 2003. They were married for 44 years. In 2003, Paulson sold her home following her husband's death and moved to Iowa to be closer to her daughters and their families.
Barbara Paulson died in Des Moines, Iowa, on February 26, 2023, at the age of 94.
Recognition and legacy
In 1959 Paulson was recognized and received her 10-year pin for her work at the Jet Propulsion Laboratory. Paulson would work at the Jet Propulsion Laboratory for 45 years, and retire in 1993. In 2016, Nathalia Holt wrote Rise of the Rocket Girls, a book about Paulson and other women who were early employees at NASA.
References
1928 births
2023 deaths
21st-century American women
American women mathematicians
Human computers
NASA people
People from Columbus, Ohio | Barbara Paulson | [
"Technology"
] | 1,222 | [
"Human computers",
"History of computing"
] |
56,035,949 | https://en.wikipedia.org/wiki/NGC%20504 | NGC 504, also occasionally referred to as PGC 5084 or UGC 935, is a lenticular galaxy located approximately 189 million light-years from the Solar System in the constellation Pisces. It was discovered on 22 November 1827 by astronomer John Herschel. The object was listed twice in the General Catalogue, precursor of the New General Catalogue, as both GC 291 and GC 292.
Observation history
Herschel discovered the object without recording a visual description. However, he noted the nebula "precedes NGC 507 by about 10 seconds and is half a field to the south of it". NGC 504 was later also independently discovered by Heinrich d'Arrest, using an 11" reflecting telescope in Copenhagen and assuming the object was new. This led to Herschel cataloguing the two observations separately as GC 291 and GC 292. The objects were later combined by John Louis Emil Dreyer with the creation of the New General Catalogue, in which the galaxy was described as "very faint, small".
See also
Lenticular galaxy
List of NGC objects (1–1000)
Pisces (constellation)
References
External links
SEDS
Lenticular galaxies
Pisces (constellation)
0504
5084
00935
Astronomical objects discovered in 1827
Discoveries by John Herschel | NGC 504 | [
"Astronomy"
] | 262 | [
"Pisces (constellation)",
"Constellations"
] |
56,036,030 | https://en.wikipedia.org/wiki/Fission%20barrier | In nuclear physics and nuclear chemistry, the fission barrier is the activation energy required for a nucleus of an atom to undergo fission. This barrier may also be defined as the minimum amount of energy required to deform the nucleus to the point where it is irretrievably committed to the fission process. The energy to overcome this barrier can come from either neutron bombardment of the nucleus, where the additional energy from the neutron brings the nucleus to an excited state and undergoes deformation, or through spontaneous fission, where the nucleus is already in an excited and deformed state.
Efforts to understand fission processes are ongoing and have been a very difficult problem since fission was first discovered by Lise Meitner, Otto Hahn, and Fritz Strassmann in 1938. While nuclear physicists understand many aspects of the fission process, there is currently no encompassing theoretical framework that gives a satisfactory account of the basic observations.
Scission
The fission process can be understood when a nucleus with some equilibrium deformation absorbs energy (through neutron capture, for example), becomes excited and deforms to a configuration known as the "transition state" or "saddle point" configuration. As the nucleus deforms, the nuclear Coulomb energy decreases while the nuclear surface energy increases. At the saddle point, the rate of change of the Coulomb energy is equal to the rate of change of the nuclear surface energy. The formation and eventual decay of this transition state nucleus is the rate-determining step in the fission process and corresponds to the passage over an activation energy barrier to the fission reaction. When this occurs, the neck between the nascent fragments disappears and the nucleus divides into two fragments. The point at which this occurs is called the "scission point".
Liquid drop model
From the description of the beginning of the fission process to the "scission point," it is apparent that the change of the shape of the nucleus is associated with a change of energy of some kind. In fact, it is the change of two types of energies: (1) the macroscopic energy related to the nuclear bulk properties as given by the liquid drop model and (2) the quantum mechanical energy associated with filling the shell model orbitals. For the nuclear bulk properties with small distortions, the surface, , and Coulomb, , energies are given by:
where and are the surface and Coulomb energies of the undistorted spherical drops, respectively, and is the quadrupole distortion parameter. When the changes in the Coulomb and surface energies (, ) are equal, the nucleus becomes unstable with respect to fission. At that point, the relationship between the undistorted surface and Coulomb energies becomes:
where is called the fissionability parameter. If , the liquid drop energy decreases with increasing , which leads to fission. If , then the liquid drop energy decreases with decreasing , which leads to spherical shapes of the nucleus.
The Coulomb and surface energies of a uniformly charged sphere can be approximated by the following expressions:
where is the atomic number of the nucleus, is the mass number of the nucleus, is the charge of an electron, is the radius of the undistorted spherical nucleus, is the surface tension per unit area of the nucleus, and . The equation for the fissionability parameter then becomes:
where the ratio of the constant is referred to as . The fissionability of a given nucleus can then be categorized relative to . As an example, plutonium-239 has a value of 36.97, while less fissionable nuclei like bismuth-209 have a value of 32.96.
For all stable nuclei, must be less than 1. In that case, the total deformation energy of nuclei undergoing fission will increase by an amount , as the nucleus deforms towards fission. This increase in potential energy can be thought of as the activation energy barrier for the fission reaction. However, modern calculations of the potential energy of deformation for the liquid drop model involve many deformation coordinates aside from and represent major computational tasks.
Shell corrections
In order to get more reasonable values for the nuclear masses in the liquid drop model, it is necessary to include shell effects. Soviet physicist Vilen Strutinsky proposed such a method using "shell correction" and corrections for nuclear pairing to the liquid drop model. In this method, the total energy of the nucleus is taken as the sum of the liquid drop model energy, , the shell, , and pairing, , corrections to this energy as:
The shell corrections, just like the liquid drop energy, are functions of the nuclear deformation. The shell corrections tend to lower the ground state masses of spherical nuclei with magic or near-magic numbers of neutrons and protons. They also tend to lower the ground state mass of mid shell nuclei at some finite deformation thus accounting for the deformed nature of the actinides. Without these shell effects, the heaviest nuclei could not be observed, as they would decay by spontaneous fission on a time scale much shorter than we can observe.
This combination of macroscopic liquid drop and microscopic shell effects predicts that for nuclei in the U-Pu region, a double-humped fission barrier with equal barrier heights and a deep secondary minimum will occur. For heavier nuclei, like californium, the first barrier is predicted to be much larger than the second barrier and passage over the first barrier is rate determining. In general, there is ample experimental and theoretical evidence that the lowest energy path in the fission process corresponds to having the nucleus, initially in an axially symmetric and mass (reflection) symmetric shape pass over the first maximum in the fission barrier with an axially asymmetric but mass symmetric shape and then to pass over the second maximum in the barrier with an axially symmetric but mass (reflection) asymmetric shape. Because of the complicated multidimensional character of the fission process, there are no simple formulas for the fission barrier heights. However, there are extensive tabulations of experimental characterizations of the fission barrier heights for various nuclei.
See also
Cold fission
Nuclear fusion
References
Nuclear physics
Nuclear fission
Nuclear chemistry
Otto Hahn
1938 in science
1938 in Germany | Fission barrier | [
"Physics",
"Chemistry"
] | 1,234 | [
"Nuclear fission",
"Nuclear chemistry",
"nan",
"Nuclear physics"
] |
56,036,280 | https://en.wikipedia.org/wiki/NGC%202090 | NGC 2090 is a spiral galaxy located in the constellation Columba. Its velocity with respect to the cosmic microwave background is 994 ± 5km/s, which corresponds to a Hubble distance of . However, 51 non-redshift measurements give a distance of . It was discovered on 29 October 1826 by Scottish astronomer James Dunlop. NGC 2090 was studied to refine the Hubble constant to an accuracy within ±10%.
See also
List of NGC objects (2001–3000)
Gallery
References
External links
SEDS
2090
Columba (constellation)
Unbarred spiral galaxies
Discoveries by James Dunlop
18261129
017819
05452-3416
-06-13-009
363-023 | NGC 2090 | [
"Astronomy"
] | 150 | [
"Columba (constellation)",
"Constellations"
] |
56,036,557 | https://en.wikipedia.org/wiki/Proof%20of%20authority | Proof of authority (PoA) is an algorithm used with blockchains that delivers comparatively fast transactions through a consensus mechanism based on identity as a stake. The most notable platforms using PoA are VeChain, Bitgert, Palm Network and Xodex.
Proof-of-authority
In PoA-based networks, transactions and blocks are validated by approved accounts, known as validators. Validators run software allowing them to put transactions in blocks. The process is automated and does not require validators to be constantly monitoring their computers. It, however, does require maintaining the computer (the authority node) uncompromised. The term was coined by Gavin Wood, co-founder of Ethereum and Parity Technologies.
With PoA, individuals earn the right to become validators, so there is an incentive to retain the position that they have gained. By attaching a reputation to identity, validators are incentivized to uphold the transaction process, as they do not wish to have their identities attached to a negative reputation. This is considered more robust than PoS (proof-of-stake) - PoS, while a stake between two parties may be even, it does not take into account each party's total holdings. This means that incentives can be unbalanced.
On the other hand, PoA only allows non-consecutive block approval from any one validator, meaning that the risk of serious damage is centralized to the authority node.
PoA is suited for both private networks and public networks, like POA Network or Eurus, where trust is distributed.
References
Algorithms
Blockchains | Proof of authority | [
"Mathematics"
] | 330 | [
"Applied mathematics",
"Algorithms",
"Mathematical logic"
] |
56,037,139 | https://en.wikipedia.org/wiki/Predecessor%20problem | In computer science, the predecessor problem involves maintaining a set of items to, given an element, efficiently query which element precedes or succeeds that element in an order. Data structures used to solve the problem include balanced binary search trees, van Emde Boas trees, and fusion trees. In the static predecessor problem, the set of elements does not change, but in the dynamic predecessor problem, insertions into and deletions from the set are allowed.
The predecessor problem is a simple case of the nearest neighbor problem, and data structures that solve it have applications in problems like integer sorting.
Definition
The problem consists of maintaining a set , which contains a subset of integers. Each of these integers can be stored with a word size of , implying that . Data structures that solve the problem support these operations:
predecessor(x), which returns the largest element in strictly smaller than
successor(x), which returns the smallest element in strictly greater than
In addition, data structures which solve the dynamic version of the problem also support these operations:
insert(x), which adds to the set
delete(x), which removes from the set
The problem is typically analyzed in a transdichotomous model of computation such as word RAM.
Data structures
One simple solution to this problem is to use a balanced binary search tree, which achieves (in Big O notation) a running time of for predecessor queries. The Van Emde Boas tree achieves a query time of , but requires space. Dan Willard proposed an improvement on this space usage with the x-fast trie, which requires space and the same query time, and the more complicated y-fast trie, which only requires space. Fusion trees, introduced by Michael Fredman and Willard, achieve query time and for predecessor queries for the static problem. The dynamic problem has been solved using exponential trees with query time, and with expected time using hashing.
Mathematical properties
There have been a number of papers proving lower bounds on the predecessor problem, or identifying what the running time of asymptotically optimal solutions would be. For example, Michael Beame and Faith Ellen proved that for all values of , there exists a value of with query time (in Big Theta notation) , and similarly, for all values of , there exists a value of such that the query time is . Other proofs of lower bounds include the notion of communication complexity.
For the static predecessor problem, Mihai Pătrașcu and Mikkel Thorup showed the following lower bound for the optimal search time, in the cell-probe model:
where the RAM has word length , the set contains integers of bits each and is represented in the RAM using words of space, and defining .
In the case where for and , the optimal search time is
and the van Emde Boas tree achieves this bound.
See also
Integer sorting
y-fast trie
Fusion tree
References
Data structures
Computational problems | Predecessor problem | [
"Mathematics"
] | 591 | [
"Mathematical problems",
"Computational problems"
] |
56,038,468 | https://en.wikipedia.org/wiki/Simon%20Rubinstein%20%28pimp%29 | Simon Rubinstein or Rubenstein (fl. 1900-1939) was an Argentine Jewish businessman and pimp, who headed the criminal organization Ashkenazum, an offshoot of the larger Zwi Migdal, in the first half of the 20th century.
Biography
Rubinstein arrived in Buenos Aires from Odessa in the year 1900, and quickly became the owner of a condom factory. He was a very successful businessman and was heavily involved in the silk trade of the country. At some point he became involved with the Zwi Migdal, which trafficked thousands of Jewish women from shtetls in Eastern Europe across the world for sex slavery.
He founded a splinter group of the Zwi Migdal, called the Ashkenazum, and had over 700 agents working for him in Argentina. Members included pimps, madams, porteras as well as the spouses of the male members. He was the owner of most of the bordellos in San Fernando, a city in the province of Buenos Aires.
Rubinstein was said to be so well connected that he stored the furniture for a Buenos Aires judge in one of his brothels. The Ashkenazum was a financial success, and like the Zwi Migdal, had a plot of land and a cemetery of its own on the outskirts of Buenos Aires. The sex trafficking trade was dismantled after a former member betrayed it to authorities, leading to the conviction and deportation of 108 pimps to Uruguay.
See also
Sexual slavery
Alfonse Pogrom
Raquel Liberman
References
1880s births
1965 deaths
Argentine pimps
Jews from the Russian Empire
Emigrants from the Russian Empire to Argentina
Businesspeople from Buenos Aires | Simon Rubinstein (pimp) | [
"Biology"
] | 337 | [
"Behavior",
"Sexuality stubs",
"Sexuality"
] |
56,039,674 | https://en.wikipedia.org/wiki/Alireza%20Mashaghi | Alireza Mashaghi is a physician-scientist and biophysicist at Leiden University. He is known for his contributions to single-molecule analysis of chaperone assisted protein folding, molecular topology and medical systems biophysics and bioengineering. He is a leading advocate for interdisciplinary research and education in medicine and pharmaceutical sciences.
Mashaghi made the first observation of direct chaperone involvement during folding of a protein, using a single molecule force spectroscopy method. This work which has been published in Nature solved a long-standing puzzle in biology. In 2017, he reported a new model for chaperone DnaK function and made a discovery that, according to Ans Hekkenberg, "overturns the decades-old textbook model of action for a protein that is central for many processes in living cells". He and his co-workers found that chaperone DnaK can recognise natively folded protein parts and thereby promotes protein folding directly. Furthermore, the lab was the first to use optical tweezers to study folding of a single protein molecule in a cytosol, revealing the collective contribution of chaperones to folding. Inspired by single-molecule analysis of biopolymers, Mashaghi and his team developed a topology framework, termed as circuit topology, which enabled studying folded molecular chains, beyond what knot theory can offer. The approach allows for topological barcoding of proteins and cellular genomes for medical applications.
Mashaghi also contributed to others areas in biophysics and bioengineering including membrane biophysics, membrane based lab-on-a-chip biosensing, and organ-on-a-chip technology. In particular, the Mashaghi team was one of the first to introduce Organ Chip technology to the field of virology. His team engineered the first chip-based disease model for Ebola hemorrhagic shock syndrome, and later extended the applicability of the platform to various viral haemorrhagic syndromes. Ebola and similar viruses pathologically alter the mechanics of human cells, which is recapitulated in organ chip models. Moreover, the Mashaghi team developed optical tweezers and acoustic force spectroscopy based assays to probe such mechanical alterations at the single cell level.
Mashaghi is also active in interdisciplinary research in ophthalmology, immunopathology and medicine. His main contributions were in the areas of ocular inflammation and immunomodulation. In 2017, he and his co-workers at Harvard developed an immunotherapy strategy to improve survival of high-risk cornea grafts. Together with his co-workers, he contributed to the use of stem cell technology and omics technology in ophthalmology and medicine. Mashaghi and his co-workers were among the first to use stem cells to reprogram innate immune cells, including neutrophil and macrophages. Additionally, his lab was the first to measure human macrophage mechanics and metabolome using single-cell approaches. Finally, in their research, Mashaghi and his co-workers are linking statistical physics and medical diagnostics; this unprecedented link between physics and medicine may allow for early and efficient diagnosis of certain diseases.
During his academic career, Mashaghi has been affiliated with various institutions including Harvard University, Leiden University, Massachusetts Institute of Technology, Delft University of Technology, ETH Zurich, Max Planck Institutes, and AMOLF. Mashaghi has published more than 100 papers in peer-reviewed scientific journals including several papers in Nature and Nature specialty journals. He worked and co-authored with Hans Clevers, Cees Dekker, Anthony A. Hyman, Colin Adams, Erica Flapan, Donald E. Ingber, Huib Bakker, Reza Dana, and Petra Schwille. He serves on editorial board of several journals including Nano Research.
In 2018, Mashaghi has been named as "Discoverer of the Year" by Leiden University. He is the recipient of several awards including an honorarium from American Chemical Society.
References
Year of birth missing (living people)
Living people
Physician-scientists
Biophysicists
Physical chemists
Dutch ophthalmologists
Harvard University staff
Academic staff of Leiden University
ETH Zurich alumni
Harvard University alumni | Alireza Mashaghi | [
"Chemistry"
] | 872 | [
"Physical chemists"
] |
56,039,802 | https://en.wikipedia.org/wiki/Ribbon%20graph | In topological graph theory, a ribbon graph is a way to represent graph embeddings, equivalent in power to signed rotation systems or graph-encoded maps. It is convenient for visualizations of embeddings, because it can represent unoriented surfaces without self-intersections
(unlike embeddings of the whole surface into three-dimensional Euclidean space) and because it omits the parts of the surface that are far away from the graph, allowing holes through which the rest of the embedding can be seen.
Ribbon graphs are also called fat graphs.
Definition
In a ribbon graph representation, each vertex of a graph is represented by a topological disk, and each edge is represented by a topological rectangle with two opposite ends glued to the edges of vertex disks (possibly to the same disk as each other).
Embeddings
A ribbon graph representation may be obtained from an embedding of a graph onto a surface (and a metric on the surface) by choosing a sufficiently small number , and representing each vertex and edge by their -neighborhoods in the surface. For small values of , the edge rectangles become long and thin like ribbons, giving the name to the representation.
In the other direction, from a ribbon graph one may find the faces of its corresponding embedding as the components of the boundary of the topological surface formed by the ribbon graph. One may recover the surface itself by gluing a topological disk to the ribbon graph along each boundary component. The partition of the surface into vertex disks, edge disks, and face disks given by the ribbon graph and this gluing process is a different but related representation of the embedding called a band decomposition.
The surface onto which the graph is embedded may be determined by whether it is orientable (true if any cycle in the graph has an even number of twists) and by its Euler characteristic.
The embeddings that can be represented by ribbon graphs are the ones in which a graph is embedded onto a 2-manifold (without boundary) and in which each face of the embedding is a topological disk.
Equivalence
Two ribbon graph representations are said to be equivalent (and define homeomorphic graph embeddings) if they are related to each other that a homeomorphism of the topological space formed by the union of the vertex disks and edge rectangles that preserves the identification of these features. Ribbon graph representations may be equivalent even if it is not possible to deform one into the other within 3d space: this notion of equivalence considers only the intrinsic topology of the representation, and not how it is embedded.
However, ribbon graphs are also applied in knot theory, and in this application weaker notions of equivalence that take into account the 3d embedding may also be used.
References
Topological graph theory | Ribbon graph | [
"Mathematics"
] | 566 | [
"Topology",
"Mathematical relations",
"Topological graph theory",
"Graph theory"
] |
56,040,144 | https://en.wikipedia.org/wiki/Coinduction%20%28anesthetics%29 | Coinduction in anesthesia is a pharmacological tool whereby a combination of sedative drugs may be used to greater effect than a single agent, achieving a smoother onset of general anesthesia. The use of coinduction allows lower doses of the same anesthetic agents to be used which provides enhanced safety, faster recovery, fewer side-effects, and more predictable pharmacodynamics. Coinduction is used in human medicine and veterinary medicine as standard practice to provide optimum anesthetic induction. The onset or induction phase of anesthesia is a critical period involving the loss of consciousness and reactivity in the patient, and is arguably the most dangerous period of a general anesthetic. A great variety of coinduction combinations are in use and selection is dependent on the patient's age and health, the specific situation, and the indication for anesthesia. As with all forms of anesthesia the resources available in the environment are a key factor.
Commonly used coinduction regimens
A standard coinduction regimen for an adult might consist of a benzodiazepine sedative amnesic such as midazolam, followed by an opioid analgesic with further sedating properties such as fentanyl which has a fast onset, then an intravenous induction agent: propofol. A muscle relaxant such as atracurium would be administered after this, though this would not strictly be a part of coinduction. For a child on the other hand, a commonly used regimen would be fentanyl, ketamin and rocuronium. In all cases the choice of agents would be tailored to the situation; for a neonatal intubation the aforementioned regimes would be inappropriate as sedation and especially amnesia are less important. Fentanyl alone would be used, followed by the short-action muscle relaxant suxamethonium: coinduction is typically not used in neonatal anesthesia.
References
Anesthesia
Pharmacology
Sedatives | Coinduction (anesthetics) | [
"Chemistry"
] | 408 | [
"Pharmacology",
"Medicinal chemistry"
] |
56,040,177 | https://en.wikipedia.org/wiki/Suzu%20ware | is a type of pre-modern Japanese pottery from the Noto Peninsula on the coast of Ishikawa prefecture, in the Hokuriku region of central Japan.
History
The production of Suzu ware began in the 12th century, at the end of the Heian period (794–1185), although the style is a continuation of Sue ware, which flourished from the much earlier Kofun period. Suzu ware pottery has been found in many locations along the coast of the Sea of Japan as far north as Hokkaido, indicating that it was a common trade good for the coastal commerce. The Muromachi period was a golden age for Suzu ware, but it soon went into decline, and vanished by the time of the Sengoku period, unable to complete with large-scale production in areas such as Tokoname. In recent times, however, production of pottery along those traditional lines has resumed.
Suzu ware was fired in tunnel-shaped kilns built into hill slopes, at over 1100 degrees. Upon extinguishing the fire, the furnace opening and the flue were sealed to starve the kiln of oxygen, causing the iron contained in the clay to turn into a characteristic shade of dark gray. No glazing was used, but some works have a natural whitish glaze caused by ash present within the kiln. Suzu ware products were typically made for everyday use, typically storage pots, water jars, or ribbed mortars used for grating food.
Suzu city has a museum dedicated to exhibits of Suzu ware with detailed explanations of its history and production process.
Suzu Pottery Kiln Sites
The is a designated National Historic Site of Japan. covering 12 separate locations in what are now the cities of Suzu and Noto where the ruins of kilns used to make Suzu ware have been found. The sites are distributed over a 15 km east to west, by 20 km north to south region, and contain over 40 kilns and were built between the 12th and 15th centuries. Most are surface kilns, and only the latest couple are completely underground. Items produced included pots, bowls, mortars, sutra containers and Buddhist statues, and water containers.
References
External links
Zuzu city official site
Japanese pottery
Culture in Ishikawa Prefecture
Suzu, Ishikawa
Noto Province
Noto, Ishikawa
Historic Sites of Japan
Japanese pottery kiln sites | Suzu ware | [
"Chemistry",
"Engineering"
] | 492 | [
"Kilns",
"Japanese pottery kiln sites"
] |
56,040,946 | https://en.wikipedia.org/wiki/Xiang%20Zhang | Zhang Xiang (; born December 1963) is a Chinese-American mechanical engineer, currently serving as the 16th president and vice-chancellor of the University of Hong Kong since July 2018.
Zhang was the inaugural Ernest S. Kuh Endowed Chaired Professor at the University of California, Berkeley in the United States, the director of the National Science Foundation Nano-scale Science and Engineering Center, the director of materials science division, and a senior faculty scientist at the Lawrence Berkeley National Laboratory.
Education
Zhang received a Bachelor of Science and a Master of Science from Nanjing University, as well as a Master of Science from the University of Minnesota. He received a Doctor of Philosophy from the University of California, Berkeley in 1996.
Career
From 1996 to 1999, he was assistant professor at the Pennsylvania State University and from 1999 to 2004, associate professor and then full professor at the University of California, Los Angeles, before joining the University of California, Berkeley. Zhang is an elected member of the United States National Academy of Engineering and of Academia Sinica, a foreign member of the Chinese Academy of Sciences, and a Fellow of the American Physical Society, the Optical Society of America (OSA), American Association for the Advancement of Science and The International Society for Optical Engineering.
Zhang published more than 390 journal papers. His research focuses on materials physics, metamaterials and nano-photonics.
On 15 December 2017, The University of Hong Kong appointed Zhang to the posts of president and vice-chancellor. It was the first time a candidate born and educated to undergraduate degree level in mainland China had been so appointed. He assumed office in July 2018.
Events
On 3 July 2019, in a statement in response to the Storming of the Legislative Council Complex two days earlier, Zhang said that he had been "disheartened by the violence" and that he "would like to condemn such acts". In response to a backlash from some 2,000 HKU students, alumni and staff, he stated on 11 July that he opposed violence "by any party, and at any juncture". Zhang agreed to a request by the HKU Student Union to participate in a forum open to students, staff, alumni and the media.
In April 2021, the Hong Kong University Students' Union criticized Zhang, and said that he was promoting national security education as a "political task" and was "destroying the autonomy of institutions."
In October 2023, Zhang was accused by whistleblowers of potential misconduct, including the purchase of a HK$2 million (US$255,370) BMW vehicle without going through an open tender.
Academic awards
1997 NSF CAREER Award
1998 SME Dell K. Allen Outstanding Young Manufacturing Engineer Award
1999 ONR Young Investigator Award
2004 to 2009 Chancellor's Professorship, UC Berkeley
2008 Time Magazine: "Top Ten Scientific Discoveries of the Year" and 50 Best Inventions of the Year"
2009 Rohsenow Lecturer, Massachusetts Institute of Technology
2011 Fred Kavli Distinguished Lectureship, Materials Research Society
2011 Miller Professorship, UC Berkeley
2011 Distinguished Visiting Scientist, University of Toronto
2012 William Reynolds Lecturer, Stanford University
2014 Fitzroy Medal
2015 Charles Russ Richards Memorial Award
2016 Max Born Award
2016 Julius Springer Award for Applied Physics
2016 Excellence Award in Scientific Leadership
2017 A. C. Eringen Medal
2017 George W. Pearsall Distinguished Lecturer, Duke University
2017 John R. and Donna S. Hall Engineering Lecturer, Vanderbilt University
2017 John and Virginia Towers Distinguished Lecturer, Michigan Technology University
2019 Physics World: Top 10 Breakthroughs for 2019
2021 SPIE Mozi Award
Honours
1 July 2019: Justice of the Peace
References
1963 births
Living people
21st-century American engineers
21st-century American physicists
American materials scientists
Chinese emigrants to the United States
Chinese materials scientists
Members of the United States National Academy of Engineering
Nanjing University alumni
Fellows of the American Physical Society
Foreign members of the Chinese Academy of Sciences
Members of Academia Sinica
Optical engineers
Pennsylvania State University faculty
Scientists from Nanjing
UC Berkeley College of Engineering alumni
University of California, Los Angeles faculty
University of Minnesota alumni
Vice-chancellors of the University of Hong Kong | Xiang Zhang | [
"Materials_science"
] | 815 | [
"Metamaterials scientists",
"Metamaterials"
] |
56,041,342 | https://en.wikipedia.org/wiki/Lubo%20Kristek | Lubo Kristek (born 8 May 1943) is a sculptor, painter and performance artist of Czech origin, who lived in West Germany from 1968 until the 1990s. He specializes in critical assemblages and happenings, in which he incorporates multiple forms of media. He created sculptures for public space. He is the author of a three-state sculptural pilgrims' way. During his more than half-century long work in the field of performance art, he formulated his theory of "holographic perception".
Life
In the 1960s, Kristek lived in a former soap factory, in Hustopeče, where he organised events incorporating music, visual art, poetry, theatre and improvisation. Testing of borders, experiments, and crossing the conventional frame is typical for his work. He follows the idea of a total work of art – Gesamtkunstwerk. At that time, he also experimented with using fire as a means of expression. He deliberately suppressed or sometimes annulled his artistic handwriting.
In 1968, Kristek emigrated to West Germany. He settled in Landsberg am Lech and lived there for almost three decades. That was also where he started the tradition of Kristek's Night Vernissages, from which his happenings evolved. From Landsberg, Kristek travelled to other places in Europe (Belgium, Luxembourg, Liechtenstein, the Netherlands, France, Italy, Spain, Republic of San Marino, Switzerland, Austria) to study and create.
Kristek was influenced by Arno Lehmann who lived in Salzburg, where Kristek used to go to meet him. In 1973, after Lehmann's death, Kristek created the sculpture Soul shaped by flame. A sphere dominates the top as a symbol of artistic heritage that Kristek adopted from Lehmann.
He was also influenced by the Austrian ethologist Eberhard Trumler (1923–1991), especially by the mechanisms of survival of the species. Kristek's existencial assemblage Expecting (1969) was created under this influence.
In 1977, Kristek travelled through the west coast of the United States and Canada with his exhibition tour American Cycle 77.
In 1989, after the Velvet Revolution, he returned to the Czech Republic. He settled in Podhradí nad Dyjí in a house where there is a gallery of his works today (Lubo Chateau). On the apex of the house, he located the sculpture Divine Ephemerality of Tone – a piano balancing on one leg. Writer Jaromír Tomeček unveiled the sculpture in 1994 and, on the basis of the artwork's title, he called the entire neighbouring area of the Thaya Kristek Valley of the Divine Ephemerality of Tone. Václav Jehlička wrote in this context in his foreword for the publication issued by the Neues Stadtmuseum, Landsberg am Lech in 2008:
Sculpture
Kristek made sculptures in several techniques, such as bronze casting, repoussé and chasing, welding and combined techniques using materials like stone, wood, metal, ceramic and found objects. His sculptures can be found as public artworks mainly in Germany and the Czech Republic.
His 1978 ceramic sculpture Birth and Simultaneously Damnation of the Sphere, is today located, as a public work of art, in a chapel at the John's Castle near Podivin, Czech Republic.
Kristek's 16-metre-high sculpture Tree of Knowledge (1981) that he made for the Ignaz-Kögler-Gymnasium (high school) in Landsberg am Lech rises up through three floors of the building. The Munich magazine Steinmetz + Bildhauer noted:
In 1988, Kristek created the bronze fountain The Drinking for the Theresianbad Greifenberg, Germany.
Kristek's metal sculpture Monument to the Five Senses (1991) is part of the collection of the Neues Stadtmuseum, Landsberg am Lech. It is located in front of the museum since 1992.
In 1992, he made a kinetic sculpture called Tree of the Wind Harp. This wind propelled musical artwork is located at the Pohansko Chateau, Czech Republic.
In 2006, Kristek created bronze sculpture The Seekers that was located on the confluence of the rivers Thaya and March. The sculpture was stolen in 2009; only a fragment left. Using the fragment, Kristek created a new metal sculpture for the place and called it The Seekers – Organic Forms. The sculpture was inaugurated in 2015.
The Czech art historian Barbora Putova wrote:
Kristek Thaya Glyptotheque
In 2005–06, he created a sculptural pilgrims' way dedicated to the river Thaya. It runs along the river Thaya through the Czech Republic, Austria and Slovakia. Kristek linked together the sculptures to inspire people to take a walk through the landscape. The route includes eleven stations, which were open by the series of ten happenings. The eleventh's station remains secret as a challenge for the pilgrim. Kristek said that the pilgrims' way "should also be a protection against the devastation of the parent riverbed. If a person experiences culture here, perhaps he will not behave so unkindly to nature." The project was under the auspices and was supported by the five regions of the three states it runs through.
Critical assemblage
Critical assemblages by Lubo Kristek address various social phenomena, such as oppression, consume approach, addiction to new technologies, and the medical ethics.
One of his early assemblages, called Vision – Burning of Christ (1964) belongs to his artworks shaped by flame. The burned Christ symbolizes "melting of faith" in Czechoslovakia at that time.
The assemblage Metastation of Abandoned Tones was created in 1975–76. It is connected to Kristek's emigration from Czechoslovakia to Germany, for which he was sentenced, in absentia, to 1.5 years in prison and the confiscation of all his property in Czechoslovakia. Kristek included his coat and hat in which he was fleeing over the border in 1968 in the assemblage. The piece is exhibited at the Ruegers Palace, Riegersburg, Austria.
Kristek addressed the subject of hidden traps in modern society in his assemblage Soundproof Aesthetic of Luxuriety, which he created in 1976.
In the 1980s, he made assemblages out of objects he found during his wanderings as in Barbed Wire of Christ (1983) created on the coast of Cantabria and Sea Horse (1986) made of material that was cast out by the sea on the Italian coast near Rome. His assemblage On the Landfill of Ages (1994) is made of industrial waste.
Kristek's artwork In the Prematurely Cloned Age of One Planet (2003) is dedicated to the ethical context of cloning. It was also a main motif of his happening Visio Sequentes or Concerning the Prematurely Cloned Age of a Planet that occurred in 2003 in Znojmo, Czech Republic.
In 2015–2017, the artist transformed his house in Brno into a monumental assemblage Kristek House.
Painting
In 1977, Kristek created a monumental altar painting for the sacral space, the cemetery chapel in Penzing, Germany. He called the 7 m high painting Transcendental Composition between Suffering and Hope.
He has created his specific vocabulary in paintings. As far back as the 1970s, one can find a road, which is mostly bordered by the arches of bridges and which rises up, in his paintings. He calls it "the heavenly highway". The oil painting The Heavenly Highway of Aunt Fränzi (1974–75), which is today part of Neues Stadtmuseum's collection, is an example of early use of this symbol.
The ballerina or the dancer is the central theme of Kristek's paintings and happenings. The development of symbol in time reflects the changes in postmodern society. In the painting Billiards for Life and the Ballerina (1987), she personifies the vitality in the world of constant metamorphosis. However, in the happening The Way of the Cross (2014), the ballerina consumes all that is left after the destruction. In the painting Peculiar Pole Vault (2016), the ballerina appears as Death.
Another Kristek's lifelong motifs are tree with two apples and intergrowth or penetration of forms.
Performance art
Kristek has organised happenings in Germany, the US, Canada, Italy, Spain, Czech Republic, Austria, Turkey, Belgium, Poland and Slovakia. His events can be described as happenings, performances or sometimes even site-specific, but he uses the original expression happening, because the involvement of the public as well as the authentic experience are crucial for him.
In 1971, he started the Kristek's Night Vernissages in his studio with garden in Landsberg am Lech. They served as a meeting point for sculptors, painters, musicians, poets, philosophers and also the visitors. The magazine Collage noted that artists from Germany, Canada, England and the USA gathered there in 1976. These experiments were at the interface between theatre, music, improvisation and ritual. Kristek studies the crowd behavior, explores the border between performer and audience, and also the death taboo in his happenings. The motifs of death, the illness of society and doom are counterbalanced by birth or rebirth, liberation from shackles and intergrowth of forms.
The magazine Medizin + Kunst analyzed Kristek's happenings:
Promenade with a Neurotic Fox
In 1975, Kristek went for a walk with a fox's skeleton on a leash on the colonnade in Landsberg am Lech and observed the reactions of the people. His aim was to study the crowd behavior and the death taboo.
Pyramidae-Klipteon II
Kristek's performances can often be interpreted as a critique of consumerism. At the climax of his happening in 2002 in Podhradí nad Dyjí, he crawled out of bowels of a cow carcass to read his manifest against the destructive and self-destructive tendencies of society.
Visio Sequentes or Concerning the Prematurely Cloned Age of a Planet
This piece took place at the Znojmo Castle, Czech Republic in 2003. The artist dissolved the boundary between the auditorium and the stage. In the climax of the happening, he dispersed the artists, mentally disabled people, amongst the spectators. The spectators were quite shocked and looked around uncomfortably to find out who is who. Kristek forced them to wonder where the boundary is and whether it exists at all. His aim was to evoke a threshold situation, when the shocked spectator is shifted outside his stereotypes and has the possibility to re-evaluate them.
Requiem for Mobile Telephones
In 2007–2010, Lubo Kristek presented an interactive assemblage Requiem for Mobile Telephones that originated in a series of his happenings. The audience gave up their mobile phones and participated in incorporating the phones in the assemblage. Kristek travelled with this happening series to the Czech Republic (Znojmo), Austria (Vienna), Germany (Landsberg am Lech) and Poland (Sucha Beskidzka) and the assemblage kept changing. The project was aimed against addiction to modern technologies.
Holographic perception
Lubo Kristek formulated his theory of holographic perception. He does not organise scenes in a linear manner in his performance art pieces. On the contrary, there are several different actions happening at the same time during Kristek's event. According to his theory, a far more plastic and holographic picture is formed in the mind of the spectator. The layering of scenes and meanings results not in a disruption of the perception, but in its sharpening. It evokes activity and creativity in the spectators.
Kristek's work in various media is interconnected. His artwork in one media becomes a means of expression for an artwork in another media. For example, his sculpture Pyramidae-Klipteon became a prop for his happening Gate to a New Dimension (2012). Then, the artist used the scene from the happening in his oil painting Landscape of Senses with Supported Clouds (2013).
The art historian Hartfrid Neunzert noted on Kristek's legacy in his foreword for the monography published by the Neues Stadtmuseum in 2008:
References
Bibliography
External links
Official Website
Czech artists
20th-century German sculptors
20th-century German painters
20th-century German male artists
German contemporary artists
German performance artists
Modern painters
Czech surrealist artists
German surrealist artists
1943 births
Living people
Czech performance artists
Multimedia artists
Body art
21st-century German painters
21st-century German male artists | Lubo Kristek | [
"Technology"
] | 2,605 | [
"Multimedia",
"Multimedia artists"
] |
56,043,631 | https://en.wikipedia.org/wiki/NGC%205114 | NGC 5114 is a lenticular galaxy located about 170 million light-years away in the constellation Centaurus. The galaxy was discovered by astronomer John Herschel on June 3, 1836.
See also
List of NGC objects (5001–6000)
References
External links
Centaurus
Lenticular galaxies
5114
46828
Astronomical objects discovered in 1836
Discoveries by John Herschel | NGC 5114 | [
"Astronomy"
] | 74 | [
"Centaurus",
"Constellations"
] |
56,045,552 | https://en.wikipedia.org/wiki/Quantum%20dot%20single-photon%20source | A quantum dot single-photon source is based on a single quantum dot placed in an optical cavity. It is an on-demand single-photon source. A laser pulse can excite a pair of carriers known as an exciton in the quantum dot. The decay of a single exciton due to spontaneous emission leads to the emission of a single photon. Due to interactions between excitons, the emission when the quantum dot contains a single exciton is energetically distinct from that when the quantum dot contains more than one exciton. Therefore, a single exciton can be deterministically created by a laser pulse and the quantum dot becomes a nonclassical light source that emits photons one by one and thus shows photon antibunching. The emission of single photons can be proven by measuring the second order intensity correlation function. The spontaneous emission rate of the emitted photons can be enhanced by integrating the quantum dot in an optical cavity. Additionally, the cavity leads to emission in a well-defined optical mode increasing the efficiency of the photon source.
History
With the growing interest in quantum information science since the beginning of the 21st century, research in different kinds of single-photon sources was growing. Early single-photon sources such as heralded photon sources that were first reported in 1985 are based on non-deterministic processes. Quantum dot single-photon sources are on-demand. A single-photon source based on a quantum dot in a microdisk structure was reported in 2000. Sources were subsequently embedded in different structures such as photonic crystals or micropillars. Adding distributed bragg reflectors (DBRs) allowed emission in a well-defined direction and increased emission efficiency. Most quantum dot single-photon sources need to work at cryogenic temperatures, which is still a technical challenge. The other challenge is to realize high-quality quantum dot single-photon sources at telecom wavelength for fiber telecommunication application. The first report on Purcell-enhanced single-photon emission of a telecom-wavelength quantum dot in a two-dimensional photonic crystal cavity with a quality factor of 2,000 shows the enhancements of the emission rate and the intensity by five and six folds, respectively.
Theory of realizing a single-photon source
Exciting an electron in a semiconductor from the valence band to the conduction band creates an excited state, a so-called exciton. The spontaneous radiative decay of this exciton results in the emission of a photon. Since a quantum dot has discrete energy levels, it can be achieved that there is never more than one exciton in the quantum dot simultaneously. Therefore, the quantum dot is an emitter of single photons. A key challenge in making a good single-photon source is to make sure that the emission from the quantum dot is collected efficiently. To do that, the quantum dot is placed in an optical cavity. The cavity can, for instance, consist of two DBRs in a micropillar (Fig. 1). The cavity enhances the spontaneous emission in a well-defined optical mode (Purcell effect), facilitating efficient guiding of the emission into an optical fiber. Furthermore, the reduced exciton lifetime (see Fig. 2) reduces the significance of linewidth broadening due to noise.
The system can then be approximated by the Jaynes-Cummings model. In this model, the quantum dot only interacts with one single mode of the optical cavity. The frequency of the optical mode is well defined. This makes the photons indistinguishable if their polarization is aligned by a polarizer. The solution of the Jaynes-Cummings Hamiltonian is a vacuum Rabi oscillation. A vacuum Rabi oscillation of a photon interacting with an exciton is known as an exciton-polariton.
To eliminate the probability of the simultaneous emission of two photons it has to be made sure that there can only be one exciton in the cavity at one time. The discrete energy states in a quantum dot allow only one excitation. Additionally, the Rydberg blockade prevents the excitation of two excitons at the same space... The electromagnetic interaction with the already existing exciton changes the energy for creating another exciton at the same space slightly. If the energy of the pump laser is tuned on resonance, the second exciton cannot be created.
Still, there is a small probability of having two excitations in the quantum dot at the same time. Two excitons confined in a small volume are called biexcitons. They interact with each other and thus slightly change their energy. Photons resulting from the decay of biexcitons have a different energy than photons resulting from the decay of excitons. They can be filtered out by letting the outgoing beam pass an optical filter.
The quantum dots can be excited both electrically and optically. For optical pumping, a pulsed laser can be used for excitation of the quantum dots. In order to have the highest probability of creating an exciton, the pump laser is tuned on resonance. This resembles a -pulse on the Bloch sphere. However, this way the emitted photons have the same frequency as the pump laser. A polarizer is needed to distinguish between them. As the direction of polarization of the photons from the cavity is random, half of the emitted photons are blocked by this filter.
Experimental realization
There are several ways to realize a quantum dot-cavity system that can act as a single-photon source. Typical cavity structures are micro-pillars, photonic crystal cavities, or tunable micro-cavities. Inside the cavity, different types of quantum dots can be used. The most widely used type are self-assembled InAs quantum dots grown in the Stranski-Krastanov growth mode, but other materials and growth methods such as local droplet etching have been used. A list of different experimental realizations is shown below:
Micropillars: In this approach, quantum dots are grown between two distributed bragg reflectors (DBR mirrors). The DBRs are typically both grown by molecular beam epitaxy (MBE). For the mirrors two materials with different indices of refraction are grown in alternate order. Their lattice parameters should match to prevent strain. A possible combination is a combination of aluminum arsenide and gallium arsenide-layers. After the first DBR, material with smaller band gap is used to grow the quantum dot above the first DBR. The second layer of DBRs can now be grown on top of the layer with the quantum dots. The diameter of the pillar is only a few microns wide. To prevent the optical mode from exiting the cavity the micropillar must act as a waveguide. Semiconductors usually have relatively high indices of refraction about n≅3. Therefore, their extraction cone is small. On a smooth surface the micropillar works as an almost perfect waveguide. However losses increase with roughness of the walls and decreasing diameter of the micropillar. The edges thus must be as smooth as possible to minimize losses. This can be achieved by structuring the sample with Electron beam lithography and processing the pillars with reactive ion etching.
Tunable micro-cavities hosting quantum dots can be also used as single-photon source. Different compared to micro-pillars, only a single DBR is grown below the quantum dots. The second part of the cavity is a curved top mirror that is physically detached from the semiconductor. The top-mirror can be moved with respect to the quantum dot position which allows tuning the cavity quantum dot coupling as needed. A further advantage over micro-pillars is that the charge-environment of the quantum dots can be stabilized by using diode structures. A disadvantage of the micro-cavity system is that it requires additional mechanical components to tune the cavity which increases the overall system size.
Microlens and solid immersion lens: To increase the brightness of a quantum dot single-photon source, also microlens structures have been used. The concept is to reduce losses due to total internal reflection similar to what can be achieved with a solid immersion lens.
Other single-photon sources are nanobeam or photonic crystal waveguides that contain quantum dots. For such structures, no DBRs are needed but can be used to improve the outcoupling efficiency. Compared to micropillars, this architecture has the advantage that on-chip routing of photons is possible. On the other side, the structure sizes are much smaller requiring more advanced nano-fabrication techniques. The close proximity of quantum dots to the surface is a further challenge.
Verification of emission of single photons
Single photon sources exhibit antibunching. As photons are emitted one at a time, the probability of seeing two photons at the same time for an ideal source is 0. To verify the antibunching of a light source, one can measure the autocorrelation function . A photon source is antibunched if ≤ . For an ideal single photon source, . Experimentally, is measured using the Hanbury Brown and Twiss effect. Using resonant excitation schemes, experimental values for are typically in the regime of just a few percent. Values down to have been reached without resonant excitation.
Indistinguishability of the emitted photons
For applications the photons emitted by a single photon source must be indistinguishable. The theoretical solution of the Jaynes-Cummings Hamiltonian is a well-defined mode in which only the polarization is random. After aligning the polarization of the photons, their indistinguishability can be measured. For that, the Hong-Ou-Mandel effect is used. Two photons of the source are prepared so that they enter a 50:50 beam splitter at the same time from the two different input channels. A detector is placed on both exits of the beam splitter. Coincidences between the two detectors are measured. If the photons are indistinguishable, no coincidences should occur. Experimentally, almost perfect indistinguishability is found.
Applications
Single-photon sources are of great importance in quantum communication science. They can be used for truly random number generators. Single photons entering a beam splitter exhibit inherent quantum indeterminacy. Random numbers are used extensively in simulations using the Monte Carlo method.
Furthermore, single photon sources are essential in quantum cryptography. The BB84 scheme is a provable secure quantum key distribution scheme. It works with a light source that perfectly emits only one photon at a time. Due to the no-cloning theorem, no eavesdropping can happen without being noticed. The use of quantum randomness while writing the key prevents any patterns in the key that can be used to decipher the code.
Apart from that, single photon sources can be used to test some fundamental properties of quantum field theory.
See also
Optical microcavity
Quantum dot
Single-photon source
References
Quantum optics
Condensed matter physics | Quantum dot single-photon source | [
"Physics",
"Chemistry",
"Materials_science",
"Engineering"
] | 2,267 | [
"Quantum optics",
"Phases of matter",
"Quantum mechanics",
"Materials science",
"Condensed matter physics",
"Matter"
] |
56,046,498 | https://en.wikipedia.org/wiki/Wilson%20operation | In topological graph theory, the Wilson operations are a group of six transformations on graph embeddings. They are generated by two involutions on embeddings, surface duality and Petrie duality, and have the group structure of the symmetric group on three elements. They are named for Stephen E. Wilson, who published them for regular maps in 1979; they were extended to all cellular graph embeddings (embeddings all of whose faces are topological disks) by .
The operations are: identity, duality, Petrie duality, Petrie dual of dual, dual of Petrie dual, and dual of Petrie dual of dual or equivalently Petrie dual of dual of Petrie dual. Together they constitute the group S3.
These operations are characterized algebraically as the only outer automorphisms of certain group-theoretic representations of embedded graphs.
Via their action on dessins d'enfants, they can be used to study the absolute Galois group of the rational numbers.
One can also define corresponding operations on the edges of an embedded graph, the partial dual and partial Petrie dual, such that performing the same operation on all edges simultaneously is equivalent to taking the surface dual or Petrie dual. These operations generate a larger group, the ribbon group, acting on the embedded graphs. As an abstract group, it is isomorphic to , the -fold product of copies of the three-element symmetric group.
References
Topological graph theory | Wilson operation | [
"Mathematics"
] | 304 | [
"Topology",
"Topological graph theory",
"Mathematical relations",
"Graph theory"
] |
56,046,803 | https://en.wikipedia.org/wiki/Near%20letter-quality%20printing | Near letter-quality (NLQ) printing is a process where dot matrix printers produce high-quality text by using multiple passes to produce higher dot density. The tradeoff for the improved print quality is reduced printing speed. Software can also be used to produce this effect. The term was coined in the 1980s to distinguish NLQ printing from true letter-quality printing, as produced by a printer based on traditional typewriter technology such as a daisy wheel, or by a laser printer.
In 1985 The New York Times described the marketing of printers with the terms "near letter-quality, or N.L.Q." as "just a neat little bit of hype", but acknowledged that they "really show their stuff in the area of fonts, print enhancements and graphics".
Technology overview
Near letter-quality is a form of impact dot matrix printing. What The New York Times called "dot-matrix impact
printing", was deemed almost good enough to be used in a business letter
Reviews in the later 1980s ranged from "good but not great" to "endowed with a simulated typewriter-like quality".
By using multiple passes of the carriage, and higher dot density, the printer could increase the effective resolution. For example, the Epson FX-86 could achieve a theoretical addressable dot-grid of 240 by 216 dots/inch using a print head with a vertical dot density of only 72 dots/inch, by making multiple passes of the print head for each line. For 240 by 144 dots/inch, the print head would make one pass, printing 240 by 72 dots/inch, then the printer would advance the paper by half of the vertical dot pitch (1/144 inch), then the print head would make a second pass. For 240 by 216 dots/inch, the print head would make three passes with smaller paper movement (1/3 vertical dot pitch,
or 1/216 inch) between the passes. To cut hardware costs, some manufacturers merely used a double strike (doubly printing each line) to increase the printed text's boldness, resulting in bolder but still jagged text. In all cases, NLQ mode incurred a severe speed penalty.
Because of the slow speed of NLQ printing, all NLQ printers have at least one "draft mode", in which the same fonts are used, but with only one pass of the print head per line. This produces lower-resolution printing, but at higher speed.
Expensive NLQ printers had multiple fonts built-in, and some had a slot where a font cartridge could be inserted to add more fonts. Printer utility software could be used to print with multiple fonts on less-expensive printers. Not all of these utilities worked with all printers and applications, however.
References
Dot matrix printers
History of computing hardware | Near letter-quality printing | [
"Technology"
] | 572 | [
"History of computing hardware",
"History of computing"
] |
56,047,338 | https://en.wikipedia.org/wiki/Robert%20Weryk | Robert J. Weryk (born 1981) is a Canadian physicist and astronomer. He currently works at the University of Hawaiʻi at Mānoa, where he discovered the first known interstellar object, ʻOumuamua. He has also published numerous articles on meteors and other astronomical topics.
References
1981 births
Living people
21st-century Canadian astronomers
Canadian physicists
University of Hawaiʻi at Mānoa faculty | Robert Weryk | [
"Astronomy"
] | 85 | [
"Astronomers",
"Astronomer stubs",
"Astronomy stubs"
] |
56,048,452 | https://en.wikipedia.org/wiki/Tepidanaerobacter | Tepidanaerobacter is a genus of anaerobic, moderately thermophilic, syntrophic bacteria from the family Tepidanaerobacteraceae.
References
Further reading
Thermoanaerobacterales
Bacteria genera
Thermophiles
Anaerobes | Tepidanaerobacter | [
"Biology"
] | 59 | [
"Bacteria",
"Anaerobes"
] |
47,520,852 | https://en.wikipedia.org/wiki/51%20Eridani | 51 Eridani is a star in the constellation Eridanus. It has an apparent magnitude of 5.22, meaning it is just visible to the unaided eye in suburban and rural skies. The primary star's absolute magnitude is 2.87. There is also a binary star named GJ 3305 which shares the same proper motion through space with it, making it overall a triple star system.
General information
Johann Bayer gave the star its Bayer designation of c Eridani, using lowercase letters once he had exhausted all the letters of the Greek alphabet, in his 1603 star chart Uranometria. It was catalogued as 51 Eridani by John Flamsteed in 1725.
Located around 97 light-years distant, it shines with a luminosity approximately 5.72 times that of the Sun and has a surface temperature of . A cold debris disk has been detected with a likely inner border of 82 astronomical units (AU). A yellow-white main-sequence star of spectral type F0V, 51 Eridani is a member of the Beta Pictoris moving group and hence thought to be around 23 million years old. Somewhat more luminous than it should be for its surface temperature, 51 Eridani has also been classified as spectral type F0IV—a type corresponding to ageing stars that have used up their core hydrogen fuel and become subgiants; however, in this case it is a phenomenon of very young stars 5 to 30 million years old that have yet to settle on the main sequence.
Photometric measurements with the TESS space telescope show that this is a Gamma Doradus-like pulsating star. Nine pulsation frequencies have been detected.
GJ 3305
51 Eridani has a companion, known as GJ 3305. The system has a common proper motion with 51 Eridani, and hence it is gravitationally bound, although it is separated by 66″ corresponding to 2,000 AU. It is a binary star system with two M-type red dwarfs. The primary has a mass of while the secondary has a mass of . The two red dwarfs themselves are separated by a semimajor axis of 9.78 ± 0.14 AU and have an eccentricity of 0.19 ± 0.02.
The star is significant as the host sun to one of the first planets to have been directly imaged in wide-orbit, and the first detected by the Gemini Planet Imager.
Planetary system
51 Eridani b is a young Jupiter-like planet and was photographed, in near-infrared light, on 21 December 2014. The study, led by Bruce Macintosh, a professor of physics at Stanford University and confirmed by Christian Marois found that methane and water were abundant in the atmosphere of the planet and its diameter was only slightly larger than Jupiter's. It is the smallest exoplanet directly imaged to date. The planetary orbit was found to be significantly eccentric by 2019.
Gaia astrometry also suggests an additional planet on orbit smaller than 51 Eridani b.
References
Cited text
F-type subgiants
Triple star systems
Beta Pictoris moving group
Planetary systems with one confirmed planet
Eridanus (constellation)
Eridani, c
1474
BD-02 963
Eridani, 51
021547
029391
J04373613-0228248
F-type main-sequence stars | 51 Eridani | [
"Astronomy"
] | 694 | [
"Eridanus (constellation)",
"Constellations"
] |
47,522,164 | https://en.wikipedia.org/wiki/List%20of%20blizzards | This is a list of blizzards, arranged alphabetically by continent. A blizzard is defined as a severe snowstorm characterized by strong sustained winds of at least and lasting for three hours or more. The list states blizzards in various countries since 1972.
Africa
Asia
Australia
Europe
North America
South America
See also
List of ice storms
List of costly or deadly hailstorms
List of dust storms with visibility of 1/4 mile or less, or meters or less
List of weather records
Lowest temperature recorded on Earth
References
Weather hazards
Severe weather and convection
Weather-related lists | List of blizzards | [
"Physics"
] | 112 | [
"Weather",
"Physical phenomena",
"Weather-related lists",
"Weather hazards"
] |
47,522,601 | https://en.wikipedia.org/wiki/Michael%20Brin%20Prize%20in%20Dynamical%20Systems | The Michael Brin Prize in Dynamical Systems, abbreviated as the Brin Prize, is awarded to mathematicians who have made outstanding advances in the field of dynamical systems and are within 14 years of their PhD. The prize is endowed by and named after Michael Brin, whose son Sergey Brin is a co-founder of Google. Michael Brin is a retired mathematician at the University of Maryland and a specialist in dynamical systems.
The first prize was awarded in 2008, between 2009 and 2017 it has been awarded bi-annually, and since 2017 annually. Artur Avila, the 2011 awardee, went on to win the Fields Medal in 2014.
From 2016, the Brin prize for young mathematicians is awarded as well, which is given to mathematicians within 4 years of their PhD.
Past winners
2008 : Giovanni Forni for his work on area-preserving flows.
2009 : Dmitry Dolgopyat for his work on rapid mixing of flows.
2011 : Artur Avila for his work on Teichmüller dynamics and interval-exchange transformations.
2013 : Omri Sarig for his work on the thermodynamics of countable Markov shifts and his Markov partition for surface diffeomorphisms.
2015 : Federico Rodriguez Hertz for his work on geometric and measure rigidity and on stable ergodicity of partially hyperbolic systems.
2017 : Lewis Bowen for creation of entropy theory for a broad class of non-amenable groups and solution of the long-standing isomorphism problem for Bernoulli actions of such groups.
2018 : Mike Hochman for his work in ergodic theory and fractal geometry.
2019 : Sébastien Gouëzel for his work on the spectral theory of transfer operators and statistical properties of hyperbolic dynamical systems and random walks on hyperbolic groups.
2020 : Corinna Ulcigrai for her work on the ergodic theory of locally Hamiltonian flows on surfaces and translation flows on periodic surfaces.
2021 : Tim Austin for his proof the weak Pinsker conjecture, for his groundbreaking approach to non-conventional multiple ergodic theorems, and his contributions to geometric group theory.
2022 : Zhiren Wang for his fundamental contributions to the study of topological and measure rigidity of higher rank actions, and his proof of Moebius disjointness for several classes of dynamical systems.
2023 : Jacopo De Simoi for his fundamental contributions to the study of Fermi acceleration, of marked length spectrum rigidity for integrable and dispersing billiards, and entropy rigidity for conservative Anosov flows in dimension 3.
2024 : Amir Mohammadi for his fundamental contributions to effective counting and equidistribution in Teichmüller and homogeneous dynamics.
Past winners of the Brin prize for young mathematicians
2016 : Simion Filip
2018 : Alex Wright and Brendon Seward
2020 : Joel Moriera
2022 : Thibault Lefeuvre and Nicole Looper
2024 : Francisco Arana-Herrera and Rohil Prasad
See also
List of mathematics awards
References
Awards established in 2008
Academic awards
Mathematics awards
Dynamical systems | Michael Brin Prize in Dynamical Systems | [
"Physics",
"Mathematics",
"Technology"
] | 636 | [
"Science and technology awards",
"Mechanics",
"Mathematics awards",
"Dynamical systems"
] |
47,523,403 | https://en.wikipedia.org/wiki/Crustacyanin | Crustacyanin is a carotenoprotein biological pigment found in the exoskeleton of lobsters and blue crabs and responsible for their blue colour. β-Crustacyanin (β-CR), is composed of two stacked astaxanthin carotenoids that absorb at λ = 580–590 nm (2.10–2.14 eV). α-crustacyanin (α-CR) is an assembly of eight β-CR protein dimers. It is a 320 kDa (atomic mass) complex containing 16 astaxanthin molecules. Although the β-CR dimer has a peak wavelength of 580 nm, α-CR exhibits a bathochromic shift to 632 nm; the mechanism and function of the additional wavelength shift is not understood.
References
Biological pigments | Crustacyanin | [
"Biology"
] | 172 | [
"Biological pigments",
"Pigmentation"
] |
47,524,110 | https://en.wikipedia.org/wiki/51%20Eridani%20b | 51 Eridani b is a "Jupiter-like" planet that orbits the young F0 V star 51 Eridani, in the constellation Eridanus. It is 96 light years away from the solar system, and it is approximately 20 million years old.
Discovery
51 Eridani b was announced in August 2015, but was discovered in December 2014 using the Gemini Planet Imager, an international project led by the Kavli Institute for Particle Astrophysics and Cosmology. 51 Eridani b is the first exoplanet discovered by the Gemini Planet Imager. The Gemini Planet Imager was specifically created to discern and evaluate dim, newer planets orbiting bright stars through “direct imaging.” Direct imaging allows astronomers to use adaptive optics to sharpen the resolution of the image of a target star, then obstruct its starlight. Any residual incoming light is then scrutinized, and the brightest spots suggest a possible planet. Prior to the discovery of 51 Eridani b, each of the directly imaged worlds previously discovered had been gas giants many times the mass of Jupiter.
Physical characteristics
The planet has a mass at least 2.6, but not more than 11. Its radius is about 1.11 times the radius of Jupiter. It orbits 11.1 AU from its host star, and has an orbital period of roughly 10,000 days. The average temperature is 807 K, which is substantially hotter than the 130 K average temperature of Jupiter, the planet in the Solar System of closest size.
Atmosphere
51 Eridani b has relatively low C/O molar ratio of 0.38. The planet has the second strongest methane signature of any exoplanet, after GJ 504 b. This methane signature, along with the low luminosity of the object, should produce additional clues as to how 51 Eridani b was formed. Astronomers also detected the presence of water and ammonia in the planet's spectrum. Atmospheric modeling favors a low surface gravity and a partly cloudy atmosphere.
References
Eridanus (constellation)
Exoplanets discovered in 2014
Exoplanets detected by direct imaging
Exoplanets detected by astrometry | 51 Eridani b | [
"Astronomy"
] | 443 | [
"Eridanus (constellation)",
"Constellations"
] |
47,524,120 | https://en.wikipedia.org/wiki/Hastatic%20order | Hastatic order is a fundamental way of breaking double "time-reversal" symmetry. It is present in the heavy-fermion compound URu2Si2. This order was dubbed hastatic from hasta, the Latin word for "spear". Its cycle is twice as complex as magnetism.
Discovery
Hastatic order was first reported in January 2013 when the heavy-fermion uranium compound URu2Si2 was cooled to nearly . It was said to produce extra heat and the heat was the main mystery. After the extra heat was released, particles were arranged at this way, making the hastatic order present on that reaction.
References
Fermions
Uranium | Hastatic order | [
"Physics",
"Materials_science"
] | 141 | [
"Fermions",
"Subatomic particles",
"Condensed matter physics",
"Particle physics",
"Particle physics stubs",
"Matter"
] |
47,524,614 | https://en.wikipedia.org/wiki/3%20Geminorum | 3 Geminorum is a blue supergiant star in the constellation Gemini. It is a small amplitude pulsating variable and a close double star, with a mean combined apparent visual magnitude of about 5.7.
3 Geminorum was found to be an α Cygni variable in 1998 and given the designation PU Geminorum. It varies by a few tenths of a magnitude with a main period of 6.807 days and a secondary period of 25 days.
3 Geminorum is also a close double star. The brighter component is the variable blue supergiant. The companion is 2.5 magnitudes fainter. The separation is about 0.6 arc-seconds. There is also a much fainter, approximately 14th magnitude, star 14" away.
Faint Hα emission lines have been detected in the spectrum of 3 Geminorum, but this is not usually expressed in published spectral classifications. An "e" is only occasionally appended to the spectral type to reflect the emission lines. 3 Geminorum has frequently been classified as a normal supergiant (luminosity class Ib), although a bright supergiant (Ia) luminosity class is now preferred.
3 Geminorum can be occulted by the Moon. Observations of these occultations can give information about the angular diameter of a star, or about close companions. Occultations of 3 Geminorum have been observed, but no double or diameter information has been published.
References
Gemini (constellation)
042087
Alpha Cygni variables
Geminorum, 03
2173
Geminorum, PU
BD+23 1226
029225
B-type supergiants | 3 Geminorum | [
"Astronomy"
] | 340 | [
"Gemini (constellation)",
"Constellations"
] |
47,524,831 | https://en.wikipedia.org/wiki/United%20States%20Drought%20Monitor | The United States Drought Monitor is a collection of measures that allows experts to assess droughts in the United States. The monitor is not an agency but a partnership between the National Drought Mitigation Center at the University of Nebraska-Lincoln, the United States Department of Agriculture, and the National Oceanic and Atmospheric Administration. Different experts provide their best judgment to outline a single map every week that shows droughts throughout the United States. The effort started in 1999 as a federal, state, and academic partnership, growing out of an initiative by the Western Governors Association to provide timely and understandable scientific information on water supply and drought for policymakers.
The monitor is produced by a rotating group of authors and incorporates review from a group of 250 climatologists, extension agents, and others across the nation. Each week the authors revise the previous map based on rainfall, snowfall, and other events, and observers' reports of how drought is affecting crops, wildlife, and other indicators. Authors balance conflicting data and reports to come up with a new map every Wednesday afternoon. The map is then released on the following Thursday morning.
See also
Palmer drought index
References
External links
Drought Monitor summary at the U.S. Drought Portal
Droughts
Droughts in the United States
Hydrology
Meteorological quantities
Climate change and agriculture | United States Drought Monitor | [
"Physics",
"Chemistry",
"Mathematics",
"Engineering",
"Environmental_science"
] | 259 | [
"Hydrology",
"Physical quantities",
"Quantity",
"Meteorological quantities",
"Environmental engineering"
] |
47,525,144 | https://en.wikipedia.org/wiki/Time%20in%20Brunei | Time in Brunei Darussalam is given by Brunei Darussalam Time (BNT), which is UTC+08:00. Brunei Darussalam 'standard time' does not currently observe daylight saving time (DST).
References
Brunei
Brunei
Geography of Brunei | Time in Brunei | [
"Physics"
] | 58 | [
"Spacetime",
"Physical quantities",
"Time",
"Time by country"
] |
47,525,447 | https://en.wikipedia.org/wiki/Time%20in%20Iraq | Time in Iraq is given by Arabia Standard Time (AST) (UTC+03:00). Iraq does not currently observe daylight saving time.
References
Iraq
Geography of Iraq | Time in Iraq | [
"Physics"
] | 37 | [
"Spacetime",
"Physical quantities",
"Time",
"Time by country"
] |
47,525,513 | https://en.wikipedia.org/wiki/Time%20in%20Jordan | Time in Jordan is on Arabia Standard Time (AST) (UTC+03:00).
Before daylight saving time (DST) was abolished in October 2022, Jordan used EET (UTC+02:00) with an offset of one hour (UTC+03:00) during the summer months. Daylight saving time typically started on Friday during 26 February to 1 April and ended on the last Friday of October, with variations before 2006. In the winter of 2012–2013, there was permanent summer time (UTC+03:00), but had been restored in December 2013, and before 1985, there was permanent standard time (UTC+02:00). In October 2022, daylight saving time was permanently abolished.
References
Jordan
Geography of Jordan | Time in Jordan | [
"Physics"
] | 156 | [
"Spacetime",
"Physical quantities",
"Time",
"Time by country"
] |
47,525,596 | https://en.wikipedia.org/wiki/Time%20in%20Kuwait | Time in Kuwait is given by Arabia Standard Time (AST) (UTC+03:00). Kuwait does not currently observe daylight saving time.
References
Kuwait
Geography of Kuwait | Time in Kuwait | [
"Physics"
] | 37 | [
"Spacetime",
"Physical quantities",
"Time",
"Time by country"
] |
47,525,614 | https://en.wikipedia.org/wiki/Time%20in%20Laos | Time in Laos is given by Indochina Time (ICT) (UTC+07:00). Laos does not observe daylight saving time. Laos shares the same time zone with Cambodia, Thailand, Vietnam, Christmas Island, and Western Indonesia.
References
Laos
Time in Southeast Asia
Geography of Laos | Time in Laos | [
"Physics"
] | 58 | [
"Spacetime",
"Physical quantities",
"Time",
"Time by country"
] |
47,525,633 | https://en.wikipedia.org/wiki/Time%20in%20Lebanon | Time in Lebanon is given by Eastern European Time (EET) (UTC+02:00) or Eastern European Summer Time (EEST) (UTC+03:00) during the summer.
Postponed time change in 2023
On 23 March 2023, two days before the scheduled switch to Eastern European Summer Time (EEST), Lebanon's government postponed the change from 25 March to 20 April. (This came within days of a DST postponement also being announced in Palestine.) No official explanation was given, but local media suggested the change was made to avoid disruption during the month of Ramadan, during which some Muslims fast from sunrise till sunset. Due to the lateness of the announcement, smart devices with "automatic time" enabled changed the time on the originally scheduled date of 25 March, and some major media outlets, including MTV, LBCI and OTV, announced that they will not abide by the decision. Different religious communities in Lebanon observed the shift independently. As a result, some places or regions in Lebanon temporarily used different time zones, causing mass confusion. On 27 March, Lebanon's prime minister Najib Mikati announced that EEST would be used starting at midnight of 29 March.
References
Lebanon
Society of Lebanon
Geography of Lebanon | Time in Lebanon | [
"Physics"
] | 258 | [
"Spacetime",
"Physical quantities",
"Time",
"Time by country"
] |
47,525,661 | https://en.wikipedia.org/wiki/Time%20in%20Maldives | Time in Maldives is given by Maldives Time (MVT) (UTC+05:00). However, some island resorts operate their own time zone, known as Maldives Island Time, up to 2 hours ahead of the official Maldives Time. The Maldives does not currently observe daylight saving time as time does not vary in Maldives due to being located in the equator.
References
Maldives
Geography of the Maldives | Time in Maldives | [
"Physics"
] | 80 | [
"Spacetime",
"Physical quantities",
"Time",
"Time by country"
] |
47,525,682 | https://en.wikipedia.org/wiki/Time%20in%20Oman | Time in Oman is given by Persian Gulf Standard Time (GST) (UTC+04:00). Oman does not observe daylight saving time.
()
References
Oman
Geography of Oman | Time in Oman | [
"Physics"
] | 39 | [
"Spacetime",
"Physical quantities",
"Time",
"Time by country"
] |
47,525,725 | https://en.wikipedia.org/wiki/Time%20in%20Qatar | Time in Qatar is given by Arabia Standard Time (AST) (UTC+03:00). Qatar does not currently observe daylight saving time.
References
2. https://www.timeinqatar.com/ Time in Qatar
Qatar
Geography of Qatar | Time in Qatar | [
"Physics"
] | 55 | [
"Spacetime",
"Physical quantities",
"Time",
"Time by country"
] |
47,525,747 | https://en.wikipedia.org/wiki/Time%20in%20Tajikistan | Time in Tajikistan is given by Tajikistan Time (TJT; UTC+05:00). Tajikistan does not currently observe daylight saving time. The IANA identifier for Tajikistan Time is Asia/Dushanbe. Daylight Saving Time starts on 9 February 2025 and ends on 7 September 2025.
IANA time zone database
Data for Tajikistan directly from zone.tab of the IANA time zone database. Columns marked with * are the columns from zone.tab itself.
History
Historic time zones for Tajikistan (both as an independent country and a Soviet state)
References
Tajikistan
Geography of Tajikistan | Time in Tajikistan | [
"Physics"
] | 120 | [
"Spacetime",
"Physical quantities",
"Time",
"Time by country"
] |
47,525,772 | https://en.wikipedia.org/wiki/Time%20in%20Turkmenistan | Time in Turkmenistan is given by Turkmenistan Time (TMT) (UTC+05:00) despite most of its territory putting it at the geographical time zone of UTC+04:00. Turkmenistan does not currently observe daylight saving time.
References
Geography of Turkmenistan | Time in Turkmenistan | [
"Physics"
] | 53 | [
"Spacetime",
"Physical quantities",
"Time",
"Time by country"
] |
47,525,786 | https://en.wikipedia.org/wiki/Time%20in%20Yemen | Time in Yemen is given by Arabia Standard Time (AST) (UTC+03:00). Yemen does not currently observe daylight saving time.
References
Geography of Yemen | Time in Yemen | [
"Physics"
] | 36 | [
"Spacetime",
"Physical quantities",
"Time",
"Time by country"
] |
47,525,865 | https://en.wikipedia.org/wiki/Time%20in%20South%20Ossetia | Time in South Ossetia, which claims independence but is widely recognized as being part of Georgia, is given by Moscow Standard Time (MSK; UTC+03:00). South Ossetia does not currently observe daylight saving time.
History
South Ossetia switched from Georgia Standard Time to Moscow Standard Time on 26 October 2014.
References
South Ossetia
Geography of South Ossetia | Time in South Ossetia | [
"Physics"
] | 81 | [
"Spacetime",
"Physical quantities",
"Time",
"Time by country"
] |
47,525,925 | https://en.wikipedia.org/wiki/Jenny%20McNulty | Jennifer McNulty is an American mathematician and academic administrator, the dean of the College of Arts and Sciences at the University of Alaska Anchorage. Her research is in combinatorics, specializing in matroid theory and graph theory.
Education and career
McNulty majored in both chemistry and mathematics at Providence College, a Catholic university in Rhode Island, graduating in 1985. After earning a master's degree in mathematics at Stony Brook University, she completed her Ph.D. in 1993 at the University of North Carolina at Chapel Hill. Her dissertation, Affine Hyperplane Arrangements and Oriented Matroids, was supervised by Thomas H. Brylawski.
She joined the University of Montana as an assistant professor in 1993, earned tenure there in 1997, and was promoted to full professor in 2004. She was chair of the Pacific Northwest Section of the Mathematical Association of America from 1998 to 2002. She became associate dean of the School of Humanities and Sciences at the University of Montana in 2010, and acting dean in 2018. Also in 2018, she traveled to the University of Gondar in Ethiopia as a Fulbright Scholar, working with mathematicians there on curriculum design, mentoring a new group of female faculty with little prior teaching experience that the university had recently hired, and building connections between the University of Gondar and University of Montana.
In 2020 she moved from the University of Montana to an affiliated university, the University of Montana Western, as interim provost and vice chancellor of academic and student affairs. She moved to the University of Alaska Anchorage as dean of the College of Arts and Sciences in 2021.
Book
With Gary Gordon of Lafayette College, McNulty is the author of the book Matroids: a Geometric Introduction (Cambridge University Press, 2012).
References
Year of birth missing (living people)
Living people
American mathematicians
American women mathematicians
Graph theorists
Providence College alumni
Stony Brook University alumni
University of North Carolina at Chapel Hill alumni
University of Montana faculty
University of Alaska Anchorage faculty | Jenny McNulty | [
"Mathematics"
] | 390 | [
"Mathematical relations",
"Graph theory",
"Graph theorists"
] |
47,526,601 | https://en.wikipedia.org/wiki/Flip%20graph | In mathematics, a flip graph is a graph whose vertices are combinatorial or geometric objects, and whose edges link two of these objects when they can be obtained from one another by an elementary operation called a flip. Flip graphs are special cases of geometric graphs.
Among notable flip graphs, one finds the 1-skeleton of polytopes such as associahedra or cyclohedra.
Examples
A prototypical flip graph is that of a convex -gon . The vertices of this graph are the triangulations of , and two triangulations are adjacent in it whenever they differ by a single interior edge. In this case, the flip operation consists in exchanging the diagonals of a convex quadrilateral. These diagonals are the interior edges by which two triangulations adjacent in the flip graph differ. The resulting flip graph is both the Hasse diagram of the Tamari lattice and the 1-skeleton of the -dimensional associahedron.
This basic construction can be generalized in a number of ways.
Finite sets of points in Euclidean space
Let be a triangulation of a finite set of points . Under some conditions, one may transform into another triangulation of by a flip. This operation consists in modifying the way triangulates a circuit (a minimally affinely dependent subset of ). More precisely, if some triangulation of a circuit is a subset of , and if all the cells (faces of maximal dimension) of have the same link in , then one can perform a flip within by replacing by , where
and is, by Radon's partition theorem, the unique other triangulation of . The conditions just stated, under which a flip is possible, make sure that this operation results in a triangulation of . The corresponding flip graph, whose vertices are the triangulations of and whose edges correspond to flips between them, is a natural generalization of the flip graph of a convex polygon, as the two flip graphs coincide when is the set of the vertices of a convex -gon.
Topological surfaces
Another kind of flip graphs is obtained by considering the triangulations of a topological surface: consider such a surface , place a finite number of points on it, and connect them by arcs in such a way that any two arcs never cross. When this set of arcs is maximal, it decomposes into triangles. If in addition there are no multiple arcs (distinct arcs with the same pair of vertices), nor loops, this set of arcs defines a triangulation of .
In this setting, two triangulations of that can be obtained from one another by a continuous transformation are identical.
Two triangulations are related by a flip when they differ by exactly one of the arcs they are composed of. Note that, these two triangulations necessarily have the same number of vertices. As in the Euclidean case, the flip graph of is the graph whose vertices are the triangulations of with vertices and whose edges correspond to flips between them. This definition can be straightforwardly extended to bordered topological surfaces.
The flip graph of a surface generalises that of a -gon, as the two coincide when the surface is a topological disk with points placed on its boundary.
Other flip graphs
A number of other flip graphs can be defined using alternative definitions of a triangulation. For instance, the flip graph whose vertices are the centrally-symmetric triangulations of a -gon and whose edges correspond to the operation of doing two centrally-symmetric flips is the 1-skeleton of the -dimensional cyclohedron. One can also consider an alternative flip graph of a topological surface, defined by allowing multiple arcs and loops in the triangulations of this surface.
Flip graphs may also be defined using combinatorial objects other than triangulations. An example of such combinatorial objects are the domino tilings of a given region in the plane. In this case, a flip can be performed when two adjacent dominos cover a square: it consists in rotating these dominos by 90 degrees around the center of the square, resulting in a different domino tiling of the same region.
Properties
Polytopality
Apart from associahedra and cyclohedra, a number of polytopes have the property that their 1-skeleton is a flip graph. For instance, if is a finite set of points in , the regular triangulations of are the ones that can be obtained by projecting some faces of a -dimensional polytope on . The subgraph induced by these triangulations in the flip graph of is the 1-skeleton of a polytope, the secondary polytope of .
Connectedness
Polytopal flip graphs are, by this property, connected. As shown by Klaus Wagner in the 1930s, the flip graph of the topological sphere is connected. Among the connected flip graphs, one also finds the flip graphs of any finite 2-dimensional set of points. In higher dimensional Euclidean spaces, the situation is much more complicated. Finite sets of points of with disconnected flip graphs have been found whenever is at least 5.
The flip graph of the vertex set of the 4-dimensional hypercube is known to be connected. However, it is yet unknown whether the flip graphs of finite 3- and 4-dimensional sets of points are always connected or not.
Diameter
The maximum number of flips required to transform a triangulation into another is the diameter of the flip graph. The diameter of the flip graph of a convex -gon has been obtained by Daniel Sleator, Robert Tarjan, and William Thurston when is sufficiently large and by Lionel Pournin for all . This diameter is equal to when .
The diameter of other flip graphs has been studied. For instance Klaus Wagner provided a quadratic upper bound on the diameter of the flip graph of a set of unmarked points on the sphere. The current upper bound on the diameter is , while the best-known lower bound is . The diameter of the flip graphs of arbitrary topological surfaces with boundary has also been studied and is known exactly in several cases.
See also
Flip distance
Rotation distance
References
Application-specific graphs
Geometric graph theory | Flip graph | [
"Mathematics"
] | 1,266 | [
"Geometric graph theory",
"Mathematical relations",
"Graph theory"
] |
47,527,696 | https://en.wikipedia.org/wiki/Campus%20of%20Justice%20%28Madrid%29 | The Campus of Justice is an ongoing urban development project in Madrid, Spain, part of the broader Valdebebas development area in the eastern part of the city, adjacent to Madrid-Barajas International Airport. The goal of the project is to group together many local and regional courts in Madrid in one location, with all buildings using a circular architectural motif.
In 2014, the €500 million project was cancelled in the wake of the Great Recession, with only one building erected.
In December 2020, the first building on the campus was opened for public use, as the Institute of Legal Medicine and Forensic Sciences, containing facilities for autopsies and biosafety level 3 laboratories.
References
Barajas (Madrid)
Urban planning
Projects in Europe | Campus of Justice (Madrid) | [
"Engineering"
] | 151 | [
"Urban planning",
"Architecture"
] |
47,528,829 | https://en.wikipedia.org/wiki/Schiefspiegler | The Schiefspiegler (lit. oblique reflector in German), also called tilted-component telescopes (TCT) and off-axis reflecting telescopes, are a type of reflecting telescope featuring an off-axis secondary mirror, and therefore an obstruction-free light path. This is accomplished by tilting the primary mirror so that the secondary mirror does not block incoming light. William Herschel was one of the first to have tilted the mirror of his telescope in order to avoid light loss due to the low reflectivity of his speculum metal mirror.
The obstructions in telescope tubes, such as secondary mirrors and their mechanical supports, cut off the intensity of captured light and cause diffraction. The diffraction causes artifacts such as the radial spikes that project from images of bright stars, and it also reduces the contrast of fine details. Schiefspieglers offer a significant increase in contrast, which is useful, for instance, for lunar and planetary study.
Tilting the mirrors causes severe coma and astigmatism, however as Anton Kutter showed in the 1950s, by a suitable choice of radii these aberrations can be corrected to an acceptable level.
Implementations
The 1.6 meter New Solar Telescope at the Big Bear Solar Observatory, and the 4 meter Daniel K. Inouye Solar Telescope feature off-axis designs for sensitive observations of the Sun.
References
External links
Telescopes
Telescope types
Astronomical imaging | Schiefspiegler | [
"Astronomy"
] | 288 | [
"Telescopes",
"Astronomical instruments"
] |
47,529,684 | https://en.wikipedia.org/wiki/Hilton%20Cleveland%20Downtown%20Hotel | The Hilton Cleveland Downtown Hotel (HCDH) is a skyscraper on the corner of Ontario Street and Lakeside Avenue along The Mall in downtown Cleveland, Ohio, United States. It opened in 2016, has 600 rooms and is 32 stories high. It is one of four Hilton properties in downtown Cleveland, the other three being Hilton Garden Inn, the DoubleTree Hotel Cleveland, and Hampton Inn.
The building was constructed under a partnership between the city of Cleveland and Cuyahoga County to attract larger conventions to the city of Cleveland. The agreement was entered into under the first chief executive of Cuyahoga County, Ed FitzGerald's administration and the Cleveland mayor Frank G. Jackson.
The hotel is the tallest and largest in the city. Previously, the largest hotel in the city was the Renaissance Cleveland Hotel which has 500 rooms. This is the first major hotel constructed in the city since the building of the Marriott at Key Center in 1991 at a height of 320 feet with 385 rooms. The new Hilton is managed by Teri Agosta.
Impetus for hotel
Following the completion of the new Global Center for Health Innovation and spurred by a tax over run that was raised by the county to construct that facility, the first chief executive of Cuyahoga County, Ed FitzGerald proposed the county mount a hotel project to meet demand for conventions that would otherwise overlook Cleveland which had no hotel to accommodate over 500 guests at a time since the 1990s when the Stouffer's company renovated its 1000-room Hotel Cleveland at Public Square (connected to the Terminal Tower) down to 500 rooms. The Hilton Hotel project was considered instrumental in landing the 2016 Republican National Convention.
Financing
The Hotel cost $272 million.
The city of Cleveland passed legislation that led to the financing structure for the hotel in December 2013.
Cuyahoga County followed suit by passing approval for the project in April 2014.
Design
The lead architect on the project was the Atlanta firm of Cooper Carry. The project is LEED certified and uses glass extensively in three slender towers jutting up from a four-story concrete pedestal base. It contains two ballrooms. The hotel's bar is called the Burnham in honor of Daniel Burnham, whose Cleveland Group Plan was instituted in 1903. The skyscraper was erected by the New York City firm Turner Construction.
See also
List of tallest buildings in Cleveland
References
Skyscraper hotels in Cleveland
Cleveland
Buildings and structures in Cleveland
Leadership in Energy and Environmental Design certified buildings
Hotel buildings completed in 2016
Downtown Cleveland
2016 establishments in Ohio | Hilton Cleveland Downtown Hotel | [
"Engineering"
] | 492 | [
"Building engineering",
"Leadership in Energy and Environmental Design certified buildings"
] |
64,372,846 | https://en.wikipedia.org/wiki/88%20Leonis | 88 Leonis is a wide binary star system in the equatorial constellation of Leo, the lion. The system is near the lower limit of visibility to the naked eye with an apparent visual magnitude of 6.27. It is located at a distance of 77 light years from the Sun based on parallax, but is drifting closer with a radial velocity of −4.8 km/s. It has a relatively high proper motion, traversing the celestial sphere at the rate of 0.379 arc seconds per annum.
The primary member of the system, component A, is a yellow-white hued F-type main-sequence star with a stellar classification of F9.5V. It is an estimated 5.7 billion years old and is spinning with a rotation period of 14.3 days. The star has a short magnetic activity cycle that averages around 3.5 years. A second cycle appears to vary over time, lasting 13.7 years at the start of observations then decreasing to 8.6 years over a span of 34 years of measurement. The star has 1.06 times the mass of the Sun and 1.10 times the Sun's radius. It is radiating 1.47 times the luminosity of the Sun from its photosphere at an effective temperature of 6,060 K.
The secondary, component B, is a magnitude 9.22 star at an angular separation of from the primary along a position angle of 326°. It has a class of G5 and 74% of the Sun's mass. The pair share a common proper motion through space with a projected separation of .
References
F-type main-sequence stars
Binary stars
Leo (constellation)
Durchmusterung objects
Leonis, 88
100180
056242
4437 | 88 Leonis | [
"Astronomy"
] | 362 | [
"Leo (constellation)",
"Constellations"
] |
64,374,783 | https://en.wikipedia.org/wiki/C15H22O4 | {{DISPLAYTITLE:C15H22O4}}
The molecular formula C15H22O4 (molar mass: 266.333 g/mol, exact mass: 266.1518 u) may refer to:
Agglomerin
Leptospermone
Molecular formulas | C15H22O4 | [
"Physics",
"Chemistry"
] | 63 | [
"Molecules",
"Set index articles on molecular formulas",
"Isomerism",
"Molecular formulas",
"Matter"
] |
64,377,524 | https://en.wikipedia.org/wiki/Jeanneney%20Rabearivony | Jeanneney Rabearivony is a Malagasy ecologist and herpetologist.
Life and research
Rabearivony grew up in rural Madagascar, and spent much of his childhood in the forest. The familiarity with the forest made him keenly aware of its disappearance, and set him on the path to work in environmental conservation.
Rabearivony received his MSc in Conservation Biology from the Durrell Institute of Conservation and Ecology (DICE), and a Diplome d'Etude Approffondies (DEA) in Ecology and Environmental studies from the University of Antananarivo in 1999. Thereafter he conducted his PhD on chameleon ecology and conservation at the University of Antananarivo, finishing his studies in 2013.
Rabearivony joined the WWF in July 2009 as manager of the Holistic Forest Conservation Project (PHCF) in Andapa, after being manager of humid zones for the Peregrine Fund. In this role, he works closely with local people to gain their perspectives and resource needs, helping to devise management plans that suit their requirements. He considers it imperative that the authorities managing Madagascar's forests and waters spend time in the field, in order to understand their role and the needs of the rural peoples of Madagascar, and has advocated for the coupling of local resource management with socio-economic engagement in order to improve the effectiveness of biodiversity protection.
Currently, Rabearivony is Dean of the Faculty of Sciences of the University of Antsiranana.
References
Herpetologists
21st-century scientists
Malagasy scientists
Year of birth missing (living people)
Living people
Ecologists | Jeanneney Rabearivony | [
"Environmental_science"
] | 332 | [
"Ecologists",
"Environmental scientists"
] |
64,378,911 | https://en.wikipedia.org/wiki/PIP2%20domain | PIP2 domains (also called PIP2 clusters) are a type of cholesterol-independent lipid domain formed from phosphatidylinositol and positively charged proteins in the plasma membrane. They tend to inhibit GM1 lipid raft function.
Chemical properties
Phosphatidylinositol 4,5-bisphosphate (PIP2) is an anionic signaling lipid. Its polyunsaturated acyl chains exclude it from GM1 lipid rafts. The multiple negative charges on PIP2 are thought to cluster proteins with positive charges residing in the plasma membrane leading to nanoscale clusters. PIP3 is also clustered away from PIP2 and away from GM1 lipid rafts.
Biological function
PIP2 domains inhibit GM1 domain function by attracting palmitoylated proteins away from GM1 lipid rafts. For this to occur, a protein must be both palmitoylated and bind PIP2. Presumably PIP2 could also antagonize PIP3 localization but this has not been shown directly.
PLD2
Phospholipase D2 (PLD2) binds PIP2 and localizes with lipid rafts. Increases in cholesterol overcome PIP2 binding and sequester PLD2 into GM1 lipid rafts away from its substrate phosphatidylcholine. Efflux of cholesterol causes PLD2 to translocate to PIP2 domains where it is activated by substrate presentation. Both PIP2 signaling and cholesterol signaling regulate the enzyme.
ACE2 receptor
Angiotensin converting enzyme (ACE2) is regulated by PIP2 localization. The ACE2 enzyme is palmitoylated which drives the protein into GM1 lipids. The enzyme also bind to PIP2 which moves it out of the endocytic pathway. The drug hydroxychloroquine blocks ACE2 interaction with PIP2 in multiple cell types shifting its localization.
Other
PIP2 binding proteins
PH domain
PIP2/palmitate proteins
GABAA receptor
References
Lipids | PIP2 domain | [
"Chemistry"
] | 423 | [
"Organic compounds",
"Biomolecules by chemical classification",
"Lipids"
] |
64,379,408 | https://en.wikipedia.org/wiki/JUQUEEN | JUQUEEN was a Blue Gene/Q system supercomputer built by IBM. Financed by the Helmholtz Association and the Gauss Centre for Supercomputing (GCS) in equal parts from federal funds and state funds from North Rhine-Westphalia, it was put into operation in 2012 at the Forschungszentrum Jülich as the successor to the JUGENE supercomputer.
JUQUEEN was the fastest computer in Europe and ranked 5th on the TOP500 list of the most powerful supercomputers. It was also one of the most energy-efficient systems in the world for its time and ranked 5th on the Green500 list. It consisted of 458,752 processor cores and had a maximum computing power of 5.9 petaflops.
JUQUEEN was used for several research projects, including the Human Brain Project.
JUQEEN was shut down in May 2018 after six years of operation and replaced by the successor JUWELS.
External links
Official website (archived)
References
IBM supercomputers
Supercomputing in Europe | JUQUEEN | [
"Technology"
] | 220 | [
"Supercomputing in Europe",
"Supercomputing"
] |
64,380,035 | https://en.wikipedia.org/wiki/Sphere%20packing%20in%20a%20cylinder | Sphere packing in a cylinder is a three-dimensional packing problem with the objective of packing a given number of identical spheres inside a cylinder of specified diameter and length. For cylinders with diameters on the same order of magnitude as the spheres, such packings result in what are called columnar structures.
These problems are studied extensively in the context of biology, nanoscience, materials science, and so forth due to the analogous assembly of small particles (like cells and atoms) into cylindrical crystalline structures.
The book "Columnar Structures of Spheres: Fundamentals and Applications" serves as a notable contributions to this field of study. Authored by Winkelmann and Chan, the book reviews theoretical foundations and practical applications of densely packed spheres within cylindrical confinements.
Appearance in science
Columnar structures appear in various research fields on a broad range of length scales from metres down to the nanoscale. On the largest scale, such structures can be found in botany where seeds of a plant assemble around the stem. On a smaller scale bubbles of equal size crystallise to columnar foam structures when confined in a glass tube. In nanoscience such structures can be found in man-made objects which are on length scales from a micron to the nanoscale.
Botany
Columnar structures were first studied in botany due to their diverse appearances in plants. D'Arcy Thompson analysed such arrangement of plant parts around the stem in his book "On Growth and Form" (1917). But they are also of interest in other biological areas, including bacteria, viruses, microtubules, and the notochord of the zebra fish.
One of the largest flowers where the berries arrange in a regular cylindrical form is the titan arum. This flower can be up to 3m in height and is natively solely found in western Sumatra and western Java.
On smaller length scales, the berries of the Arum maculatum form a columnar structure in autumn. Its berries are similar to that of the corpse flower, since the titan arum is its larger relative. However, the cuckoo-pint is much smaller in height (height ≈ 20 cm). The berry arrangement varies with the stem to berry size.
Another plant that can be found in many gardens of residential areas is the Australian bottlebrush. It assembles its seed capsules around a branch of the plant. The structure depends on the seed capsule size to branch size.
Foams
A further occurrence of ordered columnar arrangement on the macroscale are foam structures confined inside a glass tube. They can be realised experimentally with equal-sized soap bubbles inside a glass tube, produced by blowing air of constant gas flow through a needle dipped in a surfactant solution. By putting the resulting foam column under forced drainage (feeding it with surfactant solution from the top), the foam can be adjusted to either a dry (bubbles shaped as polyhedrons) or wet (spherical bubbles) structure.
Due to this simple experimental set-up, many columnar structures have been discovered and investigated in the context of foams with experiments as well as simulation. Many simulations have been carried out using the Surface Evolver to investigate dry structure or the hard sphere model for the wet limit where the bubbles are spherical.
In the zigzag structure the bubbles are stacked on top of each other in a continuous w-shape. For this particular structure a moving interface with increasing liquid fraction was reported by Hutzler et al. in 1997. This included an unexpected 180° twist interface, whose explanation is still lacking.
The first experimental observation of a line-slip structure was discovered by Winkelmann et al. in a system of bubbles.
Further discovered structures include complex structures with internal spheres/foam cells. Some dry foam structures with interior cells were found to consist of a chain of pentagonal dodecahedra or Kelvin cells in the centre of the tube. For many more arrangements of this type, it was observed that the outside bubble layer is ordered, with each internal layer resembling a different, simpler columnar structure by using X-ray tomography.
Nanoscience
Columnar structures have also been studied intensively in the context of nanotubes. Their physical or chemical properties can be altered by trapping identical particles inside them. These are usually done by self-assembling fullerenes such as C60, C70, or C78 into carbon nanotubes, but also boron nitride nanotubes
Such structures also assemble when particles are coated on the surface of a spherocylinder as in the context of pharmaceutical research. Lazáro et al. examined the morphologies of virus capsid proteins self-assembled around metal nanorods. Drug particles were coated as densely as possible on a spherocylinder to provide the best medical treatment.
Wu et al. built rods of the size of several microns. These microrods are created by densely packing silica colloidal particles inside cylindrical pores. By solidifying the assembled structures the microrods were imaged and examined using scanning electron microscopy (SEM).
Columnar arrangements are also investigated as a possible candidate of optical metamaterials (i.e. materials with a negative refractive index) which find applications in super lenses or optical cloaking. Tanjeem et al. are constructing such a resonator by self-assembling nanospheres on the surface of the cylinder. The nanospheres are suspended in an SDS solution together with a cylinder of diameter , much larger than the diameter of the nanospheres (). The nanospheres then stick to the surface of the cylinders by a depletion force.
Classification using phyllotactic notation
The most common way of classifying ordered columnar structures uses the phyllotactic notation, adopted from botany. It is used to describe arrangements of leaves of a plant, pine cones, or pineapples, but also planar patterns of florets in a sunflower head. While the arrangement in the former are cylindrical, the spirals in the latter are arranged on a disk. For columnar structures phyllotaxis in the context of cylindrical structures is adopted.
The phyllotactic notation describes such structures by a triplet of positive integers with . Each number , , and describes a family of spirals in the 3-dimensional packing. They count the number of spirals in each direction until the spiral repeats. This notation, however, only applies to triangular lattices and is therefore restricted to the ordered structures without internal spheres.
Types of ordered columnar structures without internal spheres
Ordered columnar structures without internal spheres are categorised into two separate classes: uniform and line-slip structures. For each structure that can be identified with the triplet , there exist a uniform structure and at least one line slip.
Uniform structure
A uniform structure is identified by each sphere having the same number of contacting neighbours. This gives each sphere an identical neighbourhood. In the example image on the side each sphere has six neighbouring contacts.
The number of contacts is best visualised in the rolled-out contact network. It is created by rolling out the contact network into a plane of height and azimuthal angle of each sphere. For a uniform structure such as the one in the example image, this leads to a regular hexagonal lattice. Each dot in this pattern represents a sphere of the packing and each line a contact between adjacent spheres.
For all uniform structures above a diameter ratio of , the regular hexagonal lattice is its characterising feature since this lattice type has the maximum number of contacts. For different uniform structures the rolled-out contact pattern only varies by a rotation in the plane. Each uniform structure is thus distinguished by its periodicity vector , which is defined by the phyllotactic triplet .
Line-slip structure
For each uniform structure, there also exists a related but different structure, called a line-slip arrangement.
The differences between uniform and line-slip structures are marginal and difficult to spot from images of the sphere packings. However, by comparing their rolled-out contact networks, one can spot that certain lines (which represent contacts) are missing.
All spheres in a uniform structure have the same number of contacts, but the number of contacts for spheres in a line slip may differ from sphere to sphere. For the example line slip in the image on the right side, some spheres count five and others six contacts. Thus a line slip structure is characterised by these gaps or loss of contacts.
Such a structure is termed line slip because the losses of contacts occur along a line in the rolled-out contact network. It was first identified by Picket et al., but not termed line slip.
The direction, in which the loss of contacts occur can be denoted in the phyllotactic notation , since each number represents one of the lattice vectors in the hexagonal lattice. This is usually indicated by a bold number.
By shearing the row of spheres below the loss of contact against a row above the loss of contact, one can regenerate two uniform structures related to this line slip. Thus, each line slip is related to two adjacent uniform structures, one at a higher and one at a lower diameter ratio .
Winkelmann et al. were the first to experimentally realise such a structure using soap bubbles in a system of deformable spheres.
Dense sphere packings in cylinders
Columnar structures arise naturally in the context of dense hard sphere packings inside a cylinder. Mughal et al. studied such packings using simulated annealing up to the diameter ratio of for cylinder diameter to sphere diameter . This includes some structures with internal spheres that are not in contact with the cylinder wall.
They calculated the packing fraction for all these structures as a function of the diameter ratio. At the peaks of this curve lie the uniform structures. In-between these discrete diameter ratios are the line slips at a lower packing density. Their packing fraction is significantly smaller than that of an unconfined lattice packing such as fcc, bcc, or hcp due to the free volume left by the cylindrical confinement.
The rich variety of such ordered structures can also be obtained by sequential depositioning the spheres into the cylinder. Chan reproduced all dense sphere packings up to using an algorithm, in which the spheres are placed sequentially dropped inside the cylinder.
Mughal et al. also discovered that such structures can be related to disk packings on a surface of a cylinder. The contact network of both packings are identical. For both packing types, it was found that different uniform structures are connected with each other by line slips.
Fu et al. extended this work to higher diameter ratios using linear programming and discovered 17 new dense structures with internal spheres that are not in contact with the cylinder wall.
A similar variety of dense crystalline structures have also been discovered for columnar packings of spheroids through Monte Carlo simulations. Such packings include achiral structures with specific spheroid orientations and chiral helical structures with rotating spheroid orientations.
Columnar structures created by rapid rotations
A further dynamic method to assemble such structures was introduced by Lee et al. Here, polymeric beads are placed together with a fluid of higher density inside a rotating lathe.
When the lathe is static, the beads float on top of the liquid. With increasing rotational speed, the centripetal force then pushes the fluid outwards and the beads toward the central axis. Hence, the beads are essentially confined by a potential given by the rotational energywhere is the mass of the beads, the distance from the central axis, and the rotational speed. Due to the proportionality, the confining potential resembles that of a cylindrical harmonic oscillator.
Depending on number of spheres and rotational speed, a variety of ordered structures that are comparable to the dense sphere packings were discovered.
A comprehensive theory to this experiment was developed by Winkelmann et al. It is based on analytic energy calculations using a generic sphere model and predicts peritectoid structure transitions.
See also
Sphere packing
Close-packing of equal spheres
Packing problems
References
External links
Becker, Aaron T. and Huang, L. "Packing spheres into a Thin Cylinder". MathWorld.
Packing problems
Spheres
Discrete geometry
Crystallography | Sphere packing in a cylinder | [
"Physics",
"Chemistry",
"Materials_science",
"Mathematics",
"Engineering"
] | 2,489 | [
"Discrete mathematics",
"Packing problems",
"Discrete geometry",
"Materials science",
"Crystallography",
"Condensed matter physics",
"Mathematical problems"
] |
64,381,684 | https://en.wikipedia.org/wiki/Inke%20Siewert | Inke Siewert (born 5 May 1980) is a professor for Inorganic Chemistry at University of Göttingen. Her research focuses on activation of small molecules by transition metal complexes and molecular electrochemistry.
Education and professional life
She finished her Abitur in 1999. She then studied chemistry at the Humboldt University of Berlin from 1999 to 2004. From 2004 to 2009 she worked on her doctorate in the group of Christian Limberg at the Humboldt University of Berlin. The topic of her dissertation was "Activation of dioxygen at novel first row transition metal complexes for biomimetic oxidation reactions". From 2009 to 2010, she was a postdoctoral research fellow at the University of Oxford in the group of Simon Aldridge. From 2011 to 2013, she was a research fellow at the University of Göttingen in the group of Franc Meyer. From 2013 to 2016, she was an Emmy Noether group leader at the same university. Since 2017, she is a professor in Inorganic Chemistry at the University of Göttingen.
Awards
2016 ADUC Prize
2015 Ernst Haage Award
References
1980 births
Living people
Inorganic chemists
21st-century German chemists
21st-century German women scientists
Humboldt University of Berlin alumni
Academic staff of the University of Göttingen | Inke Siewert | [
"Chemistry"
] | 247 | [
"Inorganic chemists"
] |
64,381,862 | https://en.wikipedia.org/wiki/Cerro%20de%20la%20Sal | The Cerro de la Sal or Cerro de Sal, (Mountain of Salt) is located in Villa Rica District of Oxapampa Province in Pasco Department, Peru. The Cerro de la Sal was an important source of salt for the pre-Columbian indigenous people of the Amazon Basin in Peru. Because of the seasonal concentration at the mountain by indigenous people (Indians), especially the Asháninka and Yanesha (Amuesha), Spanish missionaries, settlers, and soldiers were attracted to the Cerro de la Sal as early as 1635. Several attempts by Franciscan missionaries to establish Roman Catholic missions in the area were thwarted by uprisings of the indigenous people. In the late 19th century the Peruvian government established a foothold leading to the settlement of Europeans and Andean peoples in the area.
Cerro de la Sal is used loosely to refer to the surrounding region and to the chain of mountains extending eastward from the salt deposits.
Description
Google Earth locates the Cerro de la Sal about north of the town of Villa Rica. José Amich, an 18th-century Franciscan missionary, described the Cerro (mountain or hill) as shaped like a loaf of bread, running for "three leagues," , to the southwest and many more leagues to the northeast. The vein of salt was on the surface near the summit of the mountain and was "thirty varas," wide. The salt was mixed with stone and red clay. The Cerro de la Sal extends southwestern to near the Paucartambo River which merges with the Chanchamayo River from the south. Below the junction, the river was initially called the River de la Sal, but later became known as the Perené River. The rivers were the principal means of transporting the salt from the Cerro to the people living in the lowlands of the Amazon Basin.
The Cerro de la Sal has an elevation of about and is surrounded by higher mountains that rise to a maximum elevation of about . Below elevations of about the climate is tropical rainforest (Af in the Köppen Classification). Above that elevation the climate is sub-tropical (Cfb in the Köppen Classification).
Indigenous people
In pre-Columbian times, the indigenous people living in the Cerro de la Sal area had commercial relationships with the Inca Empire, but retained their independence.
The Cerro de la Sal was the preferred source of salt for the region to the east called the Gran Pajonal with indications that it was traded as far away as Brazil to the Tupi people, despite the difficulty of transporting water-soluble salt in a humid region. The Asháninka or Campa who lived in the Amazon basin east of the Cerro and in the Gran Pajonal, seem to have exercised control over the salt deposits, bartering the rights to mine the salt for feathers, birds, monkeys, clothes, and other items with other peoples. The Yanesa (Amuesha), who lived north of the Cerro, were also present.
The Asháninka and others congregated near the Cerro by the hundreds in the comparatively dry months of July through September to mine the salt. The workers cut blocks of salt from the vein weighing approximately each. Each block was carried by a porter a few kilometers to the Paucartambo River. The salt was loaded onto balsa wood rafts and transported down the river to the peoples living in the low jungles of the Amazon Basin. As many as 600 rafts per season carried salt down the rivers.
During the other nine months of the year the Cerro de la Sal was almost abandoned. A Spanish expedition in May 1691 found only 44 people there of whom a few were mining salt. Reasons for the seasonality of people at the Cerro de la Sal include the difficulty of navigating the flooded highland rivers during the rainy season and the fact that the Cerro has an elevation above the maximum elevation for the cultivation of manioc, the principal food crop of the indigenous people of the low jungles.
Catholic missionaries
The Spanish religious, military and secular authorities realized the strategic importance of the Cerro de la Sal early in the 17th century. Roman Catholic Franciscan missionaries were attracted to the Cerro de la Sal because of the seasonal congregation of large numbers of indigenous people there. A large number of Christian missions collectively called the Cerro de la Sal missions would be established in the region. In 1635 a Franciscan mission was established at Quimiri, later La Merced, and the Franciscans requested 50 Spanish soldiers to control access to the salt mines to bring the indigenous people under the control of the Spanish. The indigenous people were resistant. In 1637, the pioneering missionaries, Jerónimo Jimenez and Cristóbal Larrios, and five more Spaniards were killed by the indigenous. In 1641 and 1645, five additional Franciscans were killed and the Cerro de la Sal missions were abandoned.
From about 1645 to 1651 a Spanish adventurer known as Pedro Bohórquez led an expedition of 40 men to the Cerro de la Sal area in search of the fabled city of Paititi, reputed to be lost in the Amazon rain forests. During a stay at Quimiri, Bohórquez and his men abused the local Asháninka people, some of whom had been converted to Christianity by the Franciscans. In 1673, the Franciscans returned again to the Cerro de la Sal area, but in 1674 a convert named Mangoré killed 5 missionaries with arrows. Mangoré opposed the Franciscan's attempt to abolish polygyny. Mangoré's attempts to wipe out the Christians ended when Christian converts killed him at Quimiri. The missions of Quimiri and Huancabamba survived that uprising, but were destroyed and three priests killed in 1694.
In 1709, the Franciscans came back to the Cerro de la Sal area, this time with more resources and personnel. From a base at the Convent of Santa Rosa de Ocopa in the Andes, they reestablished missions at Cerro de la Sal and Quimiri, and along the salt trading route down the Perene River at Metraro, Eneno, Epillo, Pichana, and San Judas Tadeo. To attract the indigenous people the missionaries distributed steel knives and fishhooks as well as religious materials. Once again the missions failed. An epidemic in 1722-1723 reduced the population of Eneno from 800 to 220 and the other Cerro de la Sal missions suffered similarly. The indigenous people avoided the missions, associating them with disease and death. From 1742 to 1752, a messianic movement headed by Juan Santos Atahualpa destroyed the missions and the Spanish lost control of Cerro de la Sal and much of the region. The indigenous people led by Juan Santos defeated Spanish military expeditions sent to the region and for the next 100 years were unmolested by the Spanish and their Peruvian successors. Eleven Franciscan missionaries in the Cerro de la Sal missions were killed by the indigenous people during the 18th century.
Peru gains control
The Peruvian government, now independent from Spain, established a fortress in 1842 at what became the town of San Ramon along the Chanchamayo River south of the Cerro de la Sal. Thus, the government began the reconquest of the region lost during the Juan Santos Atahualpa rebellion. It was a "violent conquest" and initially unsuccessful due to the opposition of the Asháninka. Military expeditions in 1868 and 1869 were unsuccessful, but destroyed or confiscated much Ashásnika property. The government proposed stationing up to 200 soldiers at the Cerro de la Sal. This was never realized, but beginning in 1873, the Peruvian government promoted the settlement of people imported from Europe. Several thousand Italians were settled south of the Cerro de la Sal in Asháninka territory and Germans and Austrians were settled north of the Cerro in Amuesha territory. In the 1890s, a British company, the Peruvian Corporation, gained a concession along the rivers near the Cerro de la Sal and sold land to British and Dutch settlers. Peruvians, including landless Peruvians displaced in the Andes, also began to migrate into the region to obtain land.
In 1896 and 1897 a Catholic priest, Gabriel Sala, visited the Cerro de la Sal. He found that European settlers had been preventing the indigenous people from mining the salt for their use and instead enslaving them to exploit the salt for commerce. The government encouraged the settlers to exploit the salt by granting it exemptions from taxes and created a Salt Monopoly to market the salt. The response of the Asháninka had been to destroy the farmsteads of British settlers. However, the advance of the European and Andean settlers (plus Chinese brought in as farm workers) during the rubber boom was inexorable and the indigenous were forced away from the Cerro de la Sal. The nearby town of Villa Rica was founded in 1928 by settlers of German ancestry from Pozuzo and coffee became the principal cash crop of the region. Until the 1980s the indigenous people continued to visit Cerro de la Sal and extract salt to carry back to their homes in the more remote parts of the Amazon Basin.
References
Edible salt
Mountains of Junín Region
Economic history of Peru
Mountains of Pasco Region
Amazon basin
History of indigenous peoples of South America | Cerro de la Sal | [
"Chemistry"
] | 1,850 | [
"Edible salt",
"Salts"
] |
64,382,191 | https://en.wikipedia.org/wiki/Cyberpunk%3A%20Edgerunners | is a cyberpunk original net animation (ONA) miniseries based on the video game Cyberpunk 2077 by Polish studio CD Projekt Red. The series was animated by Japanese animation studio Trigger under the supervision of CD Projekt and premiered on Netflix in September 2022. Set in the Cyberpunk universe created by Mike Pondsmith, the anime serves as a prequel to the game and takes place about a year before the events of Cyberpunk 2077.
Upon its release, Cyberpunk: Edgerunners received critical acclaim, with praise directed at its characters, animation, and worldbuilding. In October 2022, CD Projekt had initially announced that the anime would not be receiving a second season and stated that, while they were open to collaborating with Trigger for future projects, Cyberpunk: Edgerunners had always been planned as a standalone work. However, in September 2024, Netflix had announced a teaser regarding a collaboration between Netflix Animation, CD Projekt, and Cyberpunk 2077, stating a "return to Night City."
Synopsis
Setting
Cyberpunk: Edgerunners is set in Night City, a self-reliant metropolis located in the Free State of California that suffers from extensive corruption, cybernetic addiction, and gang violence. The city is split into six districts, each of which has its own precise living requirements, and is controlled by several megacorporations, including Arasaka and its rival Militech. The anime's story is primarily set in Santo Domingo, the oldest, poorest, and most industrial district of Night City, and takes place in 2076.
Plot
In a dystopia overrun by corruption, crime, and cybernetic implants, an impulsive but talented street kid named David Martinez, after losing everything he has in a drive-by shooting, chooses to survive on the wrong side of the law as an "edgerunner": a high-tech, black-market mercenary also known as a "cyberpunk".
Characters
A Latino American teenager who is a top student at the prestigious Arasaka Academy. Due to coming from a very poor family, he is relentlessly bullied by his classmates and feels like he does not belong at school. A sudden and devastating tragedy leads him to abandon his education and puts him on the path of becoming an edgerunner.
A young and mysterious netrunner who becomes romantically involved with David and introduces him to the criminal underworld of Night City. She has a particular hatred towards Arasaka and dreams of traveling to the Moon.
A veteran edgerunner who commands his own crew. He is one of Gloria's clients and allows David to join the crew under his guidance.
Maine's girlfriend and second-in-command.
A foul-mouthed techie and a member of Maine's crew. He is also Rebecca's older brother.
A veteran netrunner who is often cold and stoic, and a member of Maine's crew. She is also Lucy's mentor.
A member of Maine's crew who works as the group's getaway driver.
A young and trigger-happy edgerunner and a member of Maine's crew. She is also Pilar's younger sister.
A fixer who works for Militech. He has a business relationship with Maine's crew and often hires them to conduct jobs that usually involve them performing corporate espionage against Arasaka.
A bloodthirsty and fully cybernetic supersoldier who works for Arasaka as their chief of security. His English voice actor, Alec Newman, reprises the role from Cyberpunk 2077.
A local ripperdoc who helps upgrade and install David's cybernetic implants, as well as providing him with the required immunosuppressants.
David's mother and a paramedic who works herself to the bone to pay for his tuition at the Arasaka Academy.
Production and release
The series was announced during a "Night City Wire" livestream for the game on June 25, 2020, as a collaboration between CD Projekt and Trigger. Hiroyuki Imaishi directed the series, with Masahiko Otsuka and Yoshiki Usa writing scripts, Yoh Yoshinari designing the characters and serving as animation director, Yuto Kaneko and Yusuke Yoshigaki serving as assistant character designers, Hiroyuki Kaneko serving as assistant director, Hiromi Wakabayashi serving as creative director, and Akira Yamaoka serving as the show's composer. The anime's opening theme is "This Fffire" by Franz Ferdinand, while its ending theme is "Let You Down" by Dawid Podsiadło. Edgerunners also utilized songs from 2077s in-game radio stations. Rosa Walton's song "I Really Want to Stay at Your House" was featured prominently and critically praised.
Episodes
Reception
In its first week, the show debuted on Netflix's top ten list, with 14.88 million hours of viewing. Its success helped increase the sales of Cyberpunk 2077 to 20 million units sold.
Critical response
Cyberpunk: Edgerunners was acclaimed by critics and fans.
Jonathon Wilson wrote for Ready Steady Cut that in "many ways, this is the Cyberpunk story the Cyberpunk game wanted to tell and couldn't." Matt Kim of IGN praised the exploration of the hostile life in Night City, specifically the visual effects, noting more of the focus was on the city rather than on some of the characters, and calling it "a wild ride, but worth every blistering second". In a review for Polygon, Kambole Campbell praised the "visual language for various in-game concepts," as well as the "sonic diversity in its score" and found that the show's best aspect was "[its] ability to depict the psychological unmooring of its characters without feeling inauthentic."
Video game director Hideo Kojima lauded the show as well, calling it "a miracle of squeezing the trigger to the world", and compared the art and world design favorably to the 1990 OVA series Cyber City Oedo 808. Mike Pondsmith, the creator of the original Cyberpunk role-playing game also praised the show, writing "It's like seeing my brain in a big screen anime." The publisher of the tabletop Cyberpunk game, R. Talsorian, announced plans for an Edgerunners-based expansion in November 2022.
Accolades
Future
In an interview with Famitsu, CDPR community manager Satoru Honma said of Cyberpunk: Edgerunners that no plans exist for a second season but that if ever there would be, it would not be a continuation of the first season but "something completely different."
On September 19, 2024, Netflix released a short teaser for a new tie-in with Cyberpunk 2077. This followed rumors about a Cyberpunk: Edgerunners sequel and CD Projekt Red joint CEO Michał Nowakowski signaling plans for more animated tie-ins.
Other media
Lucy is scheduled to appear as a playable character via downloadable content in Guilty Gear Strive.
A prequel manga series by Asano, titled , started on Kadokawa's Comic Alive+ website on December 13, 2024. Dark Horse Comics will release the manga in English in paperback format in North America.
References
External links
2022 anime ONAs
Animated television series set in California
Anime and manga about crime
Anime and manga about organized crime
Anime and manga set in the United States
Anime based on video games
Biorobotics in fiction
CD Projekt
Crunchyroll Anime Awards winners
Cyberpunk (role-playing game)
Cyberpunk anime and manga
Dark Horse Comics titles
Fiction about corporate warfare
Fiction about malware
Fiction about nanotechnology
Fiction about prosthetics
Gangs in fiction
Megacities in fiction
Neo-noir
Netflix original anime
Polish adult animated television series
Studio Trigger
Television series set in the 2070s | Cyberpunk: Edgerunners | [
"Materials_science"
] | 1,642 | [
"Fiction about nanotechnology",
"Nanotechnology"
] |
64,382,557 | https://en.wikipedia.org/wiki/GW190521 | GW190521 (initially S190521g) was a gravitational wave signal resulting from the merger of two black holes. It was possibly associated with a coincident flash of light; if this association is correct, the merger would have occurred near a third supermassive black hole. The event was observed by the LIGO and Virgo detectors on 21 May 2019 at 03:02:29 UTC, and published on 2 September 2020. The event had a Luminosity distance of 17 billion light years away from Earth, within a 765 deg2 area towards Coma Berenices, Canes Venatici, or Phoenix.
At 85 and 66 solar masses (M☉) respectively, the two black holes comprising this merger are the largest progenitor masses observed to date. The resulting black hole had a mass equivalent to 142 times that of the Sun, making this the first clear detection of an intermediate-mass black hole. The remaining 9 solar masses were radiated away as energy in the form of gravitational waves.
Physical significance
GW190521 is a significant discovery due to the masses of the resulting large black hole and of one or both of the smaller constituent black holes. Stellar evolution theory predicts that a star cannot collapse itself into a black hole of more than about , leaving a black hole mass gap above . The and black holes observed in GW190521 are conclusively in the mass gap, indicating that it can be populated by the mergers of smaller black holes.
Only indirect evidence for intermediate mass black holes, those with between 100 and 100,000 solar masses, had been observed earlier, and it was unclear how they had formed. Researchers hypothesize that they form from a hierarchical series of mergers, in which each black hole is the result of successive mergers involving smaller black holes.
According to discovery team member Vassiliki Kalogera of Northwestern University, "this is the first and only firm/secure mass measurement of an intermediate mass black hole at the time of its birth ... Now we know reliably at least one way [such objects can form], through the merger of other black holes."
Possible electromagnetic counterpart
In June 2020, astronomers reported observations of a flash of light that might be associated with GW190521. The Zwicky Transient Facility (ZTF) reported a transient optical source within the region of the GW190521 trigger, though as the uncertainty in sky position was hundreds of square degrees, the association remains uncertain. If the two events are actually linked, the event is claimed to be the first finding of an electromagnetic source related to the merger of two black holes. Mergers of black holes do not typically emit any light. The researchers suggest that it could be explained if the merging of the two smaller black holes sent the newly formed intermediate mass black hole on a trajectory that hurtled through the accretion disk of an unrelated but nearby supermassive black hole, disrupting the disk material and producing a flare of light. The newly formed black hole would have traveled at through the disk, according to the astronomers. If this explanation is correct, the flare should repeat after about 1.6 years when the intermediate mass black hole again encounters the accretion disk. As of 2023, the status of the connection between these two events is unconfirmed.
According to Matthew Graham, lead astronomer for the study, "This supermassive black hole was burbling along for years before this more abrupt flare. The flare occurred on the right timescale, and in the right location, to be coincident with the gravitational-wave event. In our study, we conclude that the flare is likely the result of a black hole merger, but we cannot completely rule out other possibilities."
Possible eccentricity
While the original LIGO/Virgo data analysis assumed a quasi-circular inspiral waveform model, subsequent publications claimed that this source could have been significantly eccentric. Romero-Shaw et al. showed that the data is better described by a non-precessing eccentric waveform with than a spin-precessing quasi-circular model.
Using eccentric waveforms based on numerical relativity, Gayathri et al. 2020 found a best fit with and source masses for both merging black holes.
See also
Gravitational-wave astronomy
List of gravitational wave observations
Multi-messenger astronomy
Notes
References
External links
(LIGO; 3 September 2020).
(AEI; 2 September 2020).
2019 in science
2019 in outer space
Intermediate-mass black holes
Gravitational waves
May 2019 | GW190521 | [
"Physics"
] | 928 | [
"Black holes",
"Physical phenomena",
"Unsolved problems in physics",
"Intermediate-mass black holes",
"Waves",
"Gravitational waves"
] |
64,382,760 | https://en.wikipedia.org/wiki/P%C5%8Dniu%C4%81%CA%BBena | Pōniuāʻena (), also named J100758.264+211529.207 or J1007+2115, is the third most-distant quasar known, with a measured redshift of z = 7.515 or a lookback time of 13.02 billion years. Its 1.5 billion–solar mass black hole is the most distant known black hole with a mass of over one billion solar masses, and models indicate that it must have formed not later than 100 million years after the Big Bang, before reionization. Its discovery was announced in June 2020. Only the quasars ULAS J1342+0928 (z = 7.54) and J0313–1806 (z = 7.64) are known to be more distant.
The quasar was primarily observed at the Mauna Kea Observatories on the island of Hawaii; it was first discovered at the Gemini Observatory and was further identified using data from the W. M. Keck Observatory, UKIRT, Magellan Telescopes, and ALMA. Hawaiian language experts at ʻImiloa Astronomy Center gave it the name Pōniuāʻena , which "evokes the unseen spinning source of creation, surrounded by brilliance."
References
Further reading
Quasars
Supermassive black holes
Leo (constellation) | Pōniuāʻena | [
"Physics",
"Astronomy"
] | 278 | [
"Black holes",
"Galaxy stubs",
"Unsolved problems in physics",
"Supermassive black holes",
"Astronomy stubs",
"Constellations",
"Leo (constellation)"
] |
64,383,385 | https://en.wikipedia.org/wiki/Extremal%20Problems%20For%20Finite%20Sets | Extremal Problems For Finite Sets is a mathematics book on the extremal combinatorics of finite sets and families of finite sets. It was written by Péter Frankl and Norihide Tokushige, and published in 2018 by the American Mathematical Society as volume 86 of their Student Mathematical Library book series. The Basic Library List Committee of the Mathematical Association of America has suggested its inclusion in undergraduate mathematics libraries.
Topics
The book has 32 chapters. Its topics include:
Sperner's theorem, on the largest antichain in the family of subsets of a given finite set.
The Sauer–Shelah lemma, on the largest size of a family of sets that avoids shattering any set of given size.
The Erdős–Ko–Rado theorem, on the largest pairwise-intersecting family of subsets of a given finite set, with multiple proofs; the closely related Lubell–Yamamoto–Meshalkin inequality; the Hilton-Milner theorem, on the largest intersecting family with no element in common; and a conjecture of Václav Chvátal that the largest intersecting family of any downward-closed family of sets is always achieved by a family with an element in common.
The Kruskal–Katona theorem relating the size of a family of equal-sized sets and the size of the family of subsets of its sets of a smaller equal size.
Cap sets and the sunflower conjecture on families of sets with equal pairwise intersection.
Open problems including Frankl's union-closed sets conjecture.
Many other results in this area are also included.
Audience and reception
Although the book is intended for undergraduate mathematics students, reviewer Mark Hunacek suggests that readers will either need to be familiar with, or comfortable looking up, terminology for hypergraphs and metric spaces. He suggests that the appropriate audience for the book would be advanced undergraduates who have already demonstrated an interest in combinatorics. However, despite the narrowness of this group, he writes that the book will likely be very valuable to them, as the only source for this material that is written at an undergraduate level.
References
Combinatorics
Families of sets
Mathematics books
2018 non-fiction books
Publications of the American Mathematical Society | Extremal Problems For Finite Sets | [
"Mathematics"
] | 449 | [
"Discrete mathematics",
"Families of sets",
"Basic concepts in set theory",
"Combinatorics"
] |
64,383,764 | https://en.wikipedia.org/wiki/Coherent%20topos | In mathematics, a coherent topos is a topos generated by a collection of quasi-compact quasi-separated objects closed under finite products.
Deligne's completeness theorem says a coherent topos has enough points. William Lawvere noticed that Deligne's theorem is a variant of the Gödel completeness theorem for first-order logic.
See also
Spectral space
Pyknotic set
References
Peter Johnstone, Sketches of an Elephant
External links
https://ncatlab.org/nlab/show/coherent+topos
Topos theory | Coherent topos | [
"Mathematics"
] | 115 | [
"Topos theory",
"Mathematical structures",
"Category theory",
"Category theory stubs"
] |
64,384,000 | https://en.wikipedia.org/wiki/HAT-P-25 | HAT-P-25 is a G-type main-sequence star about 985 light-years away. It has a very low flare activity. The star is enriched in heavy elements, having about twice amount of metals compared to solar abundance.
Planetary system
In 2010 a transiting hot Jupiter like planet was detected. It has an equilibrium temperature of 1182 K. The stability of orbits within circumstellar habitable zone is not significantly affected by the HAT-P-25b planet.
References
Aries (constellation)
G-type main-sequence stars
Planetary systems with one confirmed planet
Planetary transit variables | HAT-P-25 | [
"Astronomy"
] | 124 | [
"Aries (constellation)",
"Constellations"
] |
64,384,341 | https://en.wikipedia.org/wiki/Switching%20control%20techniques | Switching Control Techniques address electromagnetic interference (EMI) mitigation on power electronics (PE). The design of power electronics involves overcoming three key challenges:
power losses
EMI
harmonics
Also, the use of PE introduces crucial drawbacks into the electrical grid regarding the EMI, that must be considered during its design and operation, especially when is desirable to meet the EMC constraints (e.g., CISPR 22). Dealing with static converters designed with PE, for example, can causes signal disturbances in the electromagnetic environment (near or far fields), e.g. with respect to radio receivers, vehicle navigation systems, avionics, etc.
Those disturbances are caused mainly by the high frequency interference from the semiconductor switching components inside PE. It is challenging to handle this aspect with filtering and shielding techniques as the demands for cost and size for its implementation increase, along with greater efficiency. Therefore, switching mode power supplies are used instead in order to obtain a higher efficiency.
Mitigation of electromagnetic interference
The breakthrough of semiconductor technologies and their adoption in power electronics devices provides fast power switching devices off the shelf with progressively increasing efficiency and high-density power technology in electronics systems. In order to reach the EMC requirements, it is important to better understand the dynamics behavior of the switching devices in PE and the factors which causes modifications on output waveform shaping and rate. Therefore, it is possible to distinguish two techniques of EMI suppression regarding the PEI (Power Electronics Interface) (Fig. 1): reduce the emissions at the source or make the propagation path less effective. On one hand, intervening on the source is possible by using switching control techniques (increasing the efficiency), redesigning the circuit (costly and time demanding) and using soft switching transition. On the other hand, by adding external or internal filters (also costly) it is possible to address the propagation path.
Considering that handling the electric supply is not necessary in order to modify the internal circuitry of the electronic device, e.g. inverter, converter, rectifier, so on (then cutting off costs), by using switching control techniques it is possible to increase the efficiency of the PE. Although the use of switching transistors can increase of conducted emissions generated by the power supply, it can enhance the efficiency of the controllers (e.g. as used by high-efficiency controllers). Once the fundamental component of the waveform is associated to conversion of energy (either DC or AC) and the switching frequency (even dozens of kiloHertz or above), the choice of convenient waveform profile is made regarding to the target and the PE converter constraints.
Thus, the high efficiency reached by the switching power converters is related to the use of switching devices, energy storage elements and transformers, through proper modulation activity of the switches to convert the available DC or AC and voltage or current signal waveforms of the power source into the AC or DC waveforms needed by the load. Those switching devices are mostly semiconductors such as: transistors, diodes, thyristors, Field-effect transistor etc. The high performance of switching devices is the main reason for searching an appropriate switching control technique. The two most popular methods are:
Deterministic, in which pulse-width modulation (PWM) is applicable as programmed switching method and;
Non-deterministic (or random modulation), characterized by the random PWM (RPWM) method.
The key distinction between these techniques is attributed to the fact that randomness introduces EMI noise with a spectrum continuously distributed over frequency, i.e. a uniform power across the frequency band.
Deterministic modulation
PWM is considered the most common deterministic technique. Considering the example of a DC-DC converter, a controlled switch is designed to “cut-off” the DC waveform into a pulse-shaped waveform. Therefore, the voltage of this signal alternates at the switching frequency between a maximum value and zero. The converter also controls the duty cycle (𝐷), that is, the time frame in which the switch device is turned off in each cycle. Generally, the waveform of the power electronics interface (PEI) is a steady-state periodic time function.
By the middle of 1990s, some researchers started to evaluate which frequency modulation techniques to apply to reduce EMI emissions, focusing on communications and microprocessor systems. The main concern with these latter approaches is that EMI is equally spread along the whole frequency spectrum, and these approaches do not provide any control over the bands where EMI energy is spread. This feature is crucial for telecommunications, telematics, and automation systems applications, where EMI at specific selective frequencies must be avoided. Investigations of such techniques applied to EMI reduction of digital systems is a subject of significant concern, included the introduction of a new area of research with modulation techniques to power electronics converters with randomized modulation.
As an exemplification, Fig. 2.A at shows the spectrum and Fig. 2.B shows the spectrogram of EMI shaped-noise voltage output for a programmable PWM with switching frequency in a buck converter with 𝐷 = 0.50, in accordance with CISPR A standard.
According to Fig. 2.A, the programmable switching frequency creates a significant impact by the EMI noise shape as well as the high sideband. Fig. 2.B shows the high peaks amplitude of EMI noise, at the switching frequency and their multiple harmonics.
Non-deterministic modulation
The randomness process can be performed by spreading the harmonics power existing at well-defined frequencies (i.e. discrete harmonics) through a wide range of frequencies in order to remove harmonic components of significant magnitude. With that, discrete harmonics are substantially decreased, and the harmonic power is extended across the whole spectrum as noise.
The procedure behind of most randomized modulation is related to the schemes of successive randomization of the switching pulse train (or its segments), which are independent statistically and ruled by probabilistic rules. So, the randomized modulation procedure must enable accurate control of the time-domain performance of randomized switching, in addition to spectral shaping in the frequency domain. The elementary analysis problem in randomized modulation regards the spectral characteristics of the signal (and associated waveforms) in a converter to the probabilistic structure that governs the dithering of an underlying deterministic nominal switching pattern.
In this case, the suitable approach is to analyse the randomized switching setup in the power spectrum, computed from the fourier transform (FT) of the original signal auto correlation. Note that the FT of a random signal is itself a random function, i.e., it is a random variable at each frequency. The power spectrum, on the other hand, owns convergence properties and can be estimated reliably from the available signal.
Therefore, it is possible to categorize the randomized modulation strategies as stationary.
The Fig. 3.A shows the spectrum of EMI noise shape of voltage output for RPWM with the switching frequency implemented in one Buck-Converter, and in accordance with CISPR A standard. It shows the spectrogram of EMI noise shape of voltage output for an RPWM, where it is possible to note (also in Fig. 3. A) that aleatory process inserts the continuous EMI noise shape, in low-frequencies, the EMI noise shape follows oscillatory mode with their noise value decreasing across the spectrum. Fig. 3.B, shows the spectrogram of EMI noise shape of voltage output for an RPWM, where it is possible to note (also in Fig. 3.A) that randomization process introduces the continuous
EMI noise shape, and in low-frequencies, the EMI noise shape follows oscillatory mode with their noise value decreasing across the spectrum.
See also
Power Electronics
Electromagnetic Interference
Electromagnetic Compatibility
Random modulation
List of common EMC test standards
References
Electromagnetic compatibility | Switching control techniques | [
"Engineering"
] | 1,621 | [
"Electrical engineering",
"Electromagnetic compatibility",
"Radio electronics"
] |
64,384,534 | https://en.wikipedia.org/wiki/Common%20mode%20current | Common mode current is the portion of conductor currents that are unmatched with the exactly opposite and equal magnitude currents. Common mode current cause multiconductors to act or behave like a single conductor. In electromagnetic compatibility (EMC), there are two common terms that will be found in many electromagnetic interference discussions or considered as fundamental concepts, those are Differential Mode and Common Mode. Those terms are related to coupling mechanisms. Many electrical systems contain elements that are capable to act like an antenna. Each element is capable of unintentionally emitting Radio Frequency energy through electric, magnetic, and electromagnetic means. Common Mode coupling as well as Differential Mode coupling can occur in both a conducted and radiated way.
Definitions
Differential mode (DM) is where the signal or power propagation through a conductor and return using the intended path by the designer or flowing differently in opposition to each other. Meanwhile common mode (CM) is where the parasitic circuit (unwanted) is formed between the desired circuit (main and return path) and the structure of the circuit within which it is located. The signal or power propagates in the same direction in the same circuit.
Henry Ott remarked something similar in his book. Differential mode is the result of the normal operation of the circuit and results from electric current flowing around loops formed by the electrical conductors of the circuit. Common mode is the result of parasitics in the circuit and results from undesired voltage drops in the conductors.
Clayton R. Paul provide a simple illustration that explains CM and DM terms on his book. A pair of parallel conductors with current Î1 and Î2 flowing on each conductor, which can be decomposed into CM and DM current respectively.
As shown in the figure above, the relations between Î1 , Î2 and modal current are given:
Î1= ÎC + ÎD
Î2= ÎC - ÎD
From those two equations, the modal current were obtained as follows:
ÎD= 1/2(Î1 - Î2)
ÎC= 1/2(Î1 + Î2)
The CM current flowing in each conductor is equal in magnitude and directed in the same direction, while DM current has equal magnitude but is directed in different direction.
The radiated electric field from both conductors can be superimposed to obtain the total radiated electric field. For Differential Mode Current, since the conductors are not located in close vicinity, the fields do not exactly cancel each other, but the resultant is a small net radiated electric field. Different from DM current, CM current is directed in the same direction and results in a much higher electric field because fields from both conductors will be added. So a small CM current has a much higher potential towards producing radiated emissions compared to DM current.
For conducted interference, if the interference doesn't appear between conductors, it will appear between each conductor to a third reference point, for example a structure near the conductor.
Conducted CM interference causes more problems compared to DM interference because of the possible third reference point that could include any structure that is normally not designed for the purpose. Therefore:
CM current is difficult to be predicted and controlled;
The interference varies with time because of the uncontrolled structural changes;
Can pollute variety of unrelated equipment;
The CM current can flow within a large and uncontrolled loop, increasing their potential for radiated coupling.
Measurement
Common Mode current measurement is carried out to determine the conducted interference or radiated interference that happened in an electrical system due to the high probability of unwanted field emission to the environment. It is also said that most failures are due to common mode currents on cable and the wire assemblies. Note that some common mode current returns through a third point path that could be an adjacent cable, a ground plane or another unexpected return path. Common mode currents in a circuit don't necessarily follow the designed schematics.
Henry Ott consultants explained a simple setup on measuring common mode current by putting a high frequency current clamp from Fischer Custom Communications on multi-conductors and connect it to a spectrum analyzer. It is assumed that all of the common mode current flowing on those multiconductors will travel using another return path that is unknown.
With a known transfer impedance, the common mode current measured from the multi-conductors can be determined by looking at the voltage shown at the spectrum analyzer.
That measurement technique can work on both shielded and unshielded cables.
There are many improvisation on common mode measurement method nowadays. Here are some examples: Measurement of common mode current vnd Voltage can be done simultaneously without needing to do it in separate measurements. Measurement for both common mode and differential mode current can be done using two single path Line Impedance Stabilization Networks. Radiated emission from a power cable prediction using a common mode current measurement also done in United Kingdom. Electromagnetic radiation emission from a wind turbine also performed by measuring common mode current from all of the power cables and neutral cable.
References
External links
Politecnico di Milano - Course on Science, technology, society and Wikipedia
ETOPIA - European Training network Of PhD researchers on Innovative EMI analysis and power Applications
Electromagnetic compatibility | Common mode current | [
"Engineering"
] | 1,029 | [
"Electrical engineering",
"Electromagnetic compatibility",
"Radio electronics"
] |
64,384,635 | https://en.wikipedia.org/wiki/Forward%20problem%20of%20electrocardiology | The forward problem of electrocardiology is a computational and mathematical approach to study the electrical activity of the heart through the body surface. The principal aim of this study is to computationally reproduce an electrocardiogram (ECG), which has important clinical relevance to define cardiac pathologies such as ischemia and infarction, or to test pharmaceutical intervention. Given their important functionalities and the relative small invasiveness, the electrocardiography techniques are used quite often as clinical diagnostic tests. Thus, it is natural to proceed to computationally reproduce an ECG, which means to mathematically model the cardiac behaviour inside the body.
The three main parts of a forward model for the ECG are:
a model for the cardiac electrical activity;
a model for the diffusion of the electrical potential inside the torso, which represents the extracardiac region;
some specific heart-torso coupling conditions.
Thus, to obtain an ECG, a mathematical electrical cardiac model must be considered, coupled with a diffusive model in a passive conductor that describes the electrical propagation inside the torso.
The coupled model is usually a three-dimensional model expressed in terms of partial differential equations. Such model is typically solved by means of finite element method for the solution's space evolution and semi-implicit numerical schemes involving finite differences for the solution's time evolution. However, the computational costs of such techniques, especially with three dimensional simulations, are quite high. Thus, simplified models are often considered, solving for example the heart electrical activity independently from the problem on the torso. To provide realistic results, three dimensional anatomically realistic models of the heart and the torso must be used.
Another possible simplification is a dynamical model made of three ordinary differential equations.
Heart tissue models
The electrical activity of the heart is caused by the flow of ions across the cell membrane, between the intracellular and extracellular spaces, which determines a wave of excitation along the heart muscle that coordinates the cardiac contraction and, thus, the pumping action of the heart that enables it to push blood through the circulatory system. The modeling of cardiac electrical activity is thus related to the modelling of the flow of ions on a microscopic level, and on the propagation of the excitation wave along the muscle fibers on a macroscopic level.
Between the mathematical model on the macroscopic level, Willem Einthoven and Augustus Waller defined the ECG through the conceptual model of a dipole rotating around a fixed point, whose projection on the lead axis determined the lead recordings. Then, a two-dimensional reconstruction of the heart activity in the frontal plane was possible using the Einthoven's limbs leads I, II and III as theoretical basis.
Later on, the rotating cardiac dipole was considered inadequate and was substituted by multipolar sources moving inside a bounded torso domain. The main shortcoming of the methods used to quantify these sources is their lack of details, which are however very relevant to realistically simulate cardiac phenomena.
On the other hand, microscopic models try to represent the behaviour of single cells and to connect them considering their electrical properties. These models present some challenges related to the different scales that need to be captured, in particular considering that, especially for large scale phenomena such as re-entry or body surface potential, the collective behaviour of the cells is more important than that of every single cell.
The third option to model the electrical activity of the heart is to consider a so-called "middle-out approach", where the model incorporates both lower and higher level of details. This option considers the behaviour of a block of cells, called a continuum cell, thus avoiding scale and detail problems. The model obtained is called bidomain model, which is often replaced by its simplification, the monodomain model.
Bidomain model
The basic assumption of the bidomain model is that the heart tissue can be divided in two ohmic conducting continuous media, connected but separated through the cell membrane. This media are called intracellular and extracellular regions, the former representing the cellular tissues, and the latter representing the space between cells.
The standard formulation of the bidomain model, including a dynamical model for the ionic current, is the following
where and are the transmembrane and extracellular potentials respectively, is the ionic current, which depends also from a so-called gating variable (accounting for cellular-level ionic behavior), and is an external current applied to the domain. Moreover, and are the intracellular and extracellular conductivity tensors, is the surface to volume ratio of the cell membrane and is the membrane capacitance per unit area. Here the domain represents the heart muscle.
The boundary conditions for this version of the bidomain model are obtained through the assumption that there is no flow of intracellular potential outside of the heart, which means that
where denotes the boundary of the heart domain and is the outward unit normal to .
Monodomain model
The monodomain model is a simplification of the bidomain model that, in spite of some unphysiological assumptions, is able to represent realistic electrophysiological phenomena at least for what concerns the transmembrane potential .
The standard formulation is the following partial differential equation, whose only unknown is the transmembrane potential:
where is a parameter that relates the intracellular and extracellular conductivity tensors.
The boundary condition used for this model is
Torso tissue model
In the forward problem of electrocardiography, the torso is seen as a passive conductor and its model can be derived starting from the Maxwell's equations under quasi-static assumption.
The standard formulation consists of a partial differential equation with one unknown scalar field, the torso potential . Basically, the torso model is the following generalized Laplace equation
where is the conductivity tensor and is the domain surrounding the heart, i.e. the human torso.
Derivation
As for the bidomain model, the torso model can be derived from the Maxwell's equations and the continuity equation after some assumptions. First of all, since the electrical and magnetic activity inside the body is generated at low level, a quasi-static assumption can be considered. Thus, the body can be viewed as a passive conductor, which means that its capacitive, inductive and propagative effect can be ignored.
Under quasi-static assumption, the Maxwell's equations are
and the continuity equation is
Since its curl is zero, the electrical field can be represented by the gradient of a scalar potential field, the torso potential
where the negative sign means that the current flows from higher to lower potential regions.
Then, the total current density can be expressed in terms of the conduction current and other different applied currents so that, from continuity equation,
Then, substituting () in ()
in which is the current per unit volume.
Finally, since aside from the heart there is no current source inside the torso, the current per unit volume can be set to zero, giving the generalized Laplace equation, which represents the standard formulation of the diffusive problem inside the torso
Boundary condition
The boundary conditions accounts for the properties of the media surrounding the torso, i.e. of the air around the body. Generally, air has null conductivity which means that the current cannot flow outside the torso. This is translated in the following equation
where is the unit outward normal to the torso and is the torso boundary, which means the torso surface.
Torso conductivity
Usually, the torso is considered to have isotropic conductivity, which means that the current flows in the same way in all directions. However, the torso is not an empty or homogeneous envelope, but contains different organs characterized by different conductivity coefficients, which can be experimentally obtained. A simple example of conductivity parameters in a torso that considers the bones and the lungs is reported in the following table.
Heart-torso models
The coupling between the electrical activity model and the torso model is achieved by means of suitable boundary conditions at the epicardium, i.e. at the interface surface between the heart and the torso.
The heart-torso model can be fully coupled, if a perfect electrical transmission between the two domains is considered, or can be uncoupled, if the heart electrical model and the torso model are solved separately with a limited or imperfect exchange of information between them.
Fully coupled heart-torso models
The complete coupling between the heart and the torso is obtained imposing a perfect electrical transmission condition between the heart and the torso. This is done considering the following two equations, that establish a relationship between the extracellular potential and the torso potential
This equations ensure the continuity of both the potential and the current across the epicardium.
Using these boundary conditions, it is possible to obtain two different fully coupled heart-torso models, considering either the bidomain or the monodomain model for the heart electrical activity. From the numerical viewpoint, the two models are computationally very expensive and have similar computational costs.
Alternative boundary conditions
Boundary conditions that represent a perfect electrical coupling between the heart and the torso are the most used and the classical ones. However, between the heart and the torso there is the pericardium, a sac with a double wall that contains a serous fluid which has a specific effect on the electrical transmission. Considering the capacitance and the resistive effect that the pericardium has, alternative boundary conditions that take into account this effect can be formulated as follows
Formulation with the bidomain model
The fully coupled heart-torso model, considering the bidomain model for the heart electrical activity, in its complete form is
where the first four equations are the partial differential equations representing the bidomain model, the ionic model and the torso model, while the remaining ones represent the boundary conditions for the bidomain and torso models and the coupling conditions between them.
Formulation with the monodomain model
The fully coupled heart-torso model considering the monodomain model for the electrical activity of the heart is more complicated that the bidomain problem. Indeed, the coupling conditions relate the torso potential with the extracellular potential, which is not computed by the monodomain model. Thus, it is necessary to use also the second equation of the bidomain model (under the same assumptions under which the monodomain model is derived), yielding:
This way, the coupling conditions do not need to be changed, and the complete heart-torso model is composed of two different blocks:
First the monodomain model with its usual boundary condition must be solved:
Then, the coupled model that includes the computation of the extracellular potential, the torso model and the coupling conditions must be solved:
Uncoupled heart-torso models
The fully coupled heart-torso models are very detailed models but they are also computationally expensive to solve. A possible simplification is provided by the so-called uncoupled assumption in which the heart is considered completely electrically isolated from the heart. Mathematically, this is done imposing that the current cannot flow across the epicardium, from the heart to the torso, namely
Applying this equation to the boundary conditions of the fully coupled models, it is possible to obtained two uncoupled heart-torso models, in which the electrical models can be solved separately from the torso model reducing the computational costs.
Uncoupled heart-torso model with the bidomain model
The uncoupled version of the fully coupled heart-torso model that uses the bidomain to represent the electrical activity of the heart is composed of two separated parts:
The bidomain model in its isolated form
The torso diffusive model in its standard formulation, with the potential continuity condition
Uncoupled heart-torso model with the modomain model
As in the case of the fully coupled heart-torso model which uses the monodomain model, also in the corresponding uncoupled model extracellular potential needs to be computed. In this case, three different and independent problems must be solved:
The monodomain model with its usual boundary condition:
The problem to compute the extracellular potential with a boundary condition on the epicardium prescribing no intracellular current flow:
The torso diffusive model with the potential continuity boundary condition at the epicardium:
Electrocardiogram computation
Solving the fully coupled or the uncoupled heart-torso models allows to obtain the electrical potential generated by the heart in every point of the human torso, and in particular on the whole surface of the torso. Defining the electrodes positions on the torso, it is possible to find the time evolution of the potential on such points. Then, the electrocardiograms can be computed, for example according to the 12 standard leads, considering the following formulas
where and are the standard locations of the electrodes.
Numerical methods
The heart-torso models are expressed in terms of partial differential equations whose unknowns are function of both space and time. They are in turn coupled with an ionic model which is usually expressed in terms of a system of ordinary differential equations. A variety of numerical schemes can be used for the solution of those problems. Usually, the finite element method is applied for the space discretization and semi-implicit finite-difference schemes are used for the time discretization.
Uncoupled heart-torso model are the simplest to treat numerically because the heart electrical model can be solved separately from the torso one, so that classic numerical methods to solve each of them can be applied. This means that the bidomain and monodomain models can be solved for example with a backward differentiation formula for the time discretization, while the problems to compute the extracellular potential and torso potential can be easily solved by applying only the finite element method because they are time independent.
The fully coupled heart-torso models, instead, are more complex and need more sophisticated numerical models. For example, the fully heart-torso model that uses the bidomain model for the electrical simulation of the cardiac behaviour can be solved considering domain decomposition techniques, such as a Dirichlet-Neumann domain decomposition.
Geometric torso model
To simulate and electrocardiogram using the fully coupled or uncoupled models, a three-dimensional reconstruction of the human torso is needed. Today, diagnostic imaging techniques such as MRI and CT can provide a sufficiently accurate images that allow to reconstruct in detail anatomical human parts and, thus, obtain a suitable torso geometry.
For example, the Visible Human Data is a useful dataset to create a three-dimensional torso model detailed with internal organs including the skeletal structure and muscles.
Dynamical model for the electrocardiogram
Even if the results are quite detailed, solving a three-dimensional model is usually quite expensive. A possible simplification is a dynamical model based on three coupled ordinary differential equations.
The quasi-periodicity of the heart beat is reproduced by a three-dimensional trajectory around an attracting limit cycle in the plane. The principal peaks of the ECG, which are the P,Q,R,S and T, are described at fixed angles , which give the following three ODEs
with , ,
The equations can be easily solved with classical numerical algorithms like Runge-Kutta methods for ODEs.
See also
Monodomain model
Bidomain model
Electrocardiography
References
Cardiac electrophysiology
Cardiac procedures
Electrodiagnosis
Electrophysiology
Mathematics in medicine
Medical tests
Partial differential equations
Mathematical modeling
Numerical analysis | Forward problem of electrocardiology | [
"Mathematics"
] | 3,122 | [
"Mathematical modeling",
"Applied mathematics",
"Computational mathematics",
"Mathematical relations",
"Numerical analysis",
"Mathematics in medicine",
"Approximations"
] |
64,386,913 | https://en.wikipedia.org/wiki/Vanadium-51%20nuclear%20magnetic%20resonance | Vanadium-51 nuclear magnetic resonance (51V NMR spectroscopy) is a method for the characterization of vanadium-containing compounds and materials. 51V comprises 99.75% of naturally occurring vanadium. The nucleus is quadrupolar with I = , which is not favorable for NMR spectroscopy, although its quadrupole moment and thus the linewidths are unusually small, while its magnetogyric ratio is relatively high (+7.0492 rad T−1s−1), so that 51V has 38% receptivity vs 1H. Its resonance frequency is close to that of 13C (gyromagnetic ratio = 6.728284 rad T−1s−1).
The chemical shift dispersion is great as illustrated by this series: 0 for VOCl3 (chemical shift standard), −309 for VOCl2(O-i-Pr), −506 VOCl(O-i-Pr)2, and −629 VO(O-i-Pr)3. For vanadates, the parent orthovanadate and its conjugate acid absorb at −541 ([VO4]3-) and 534 ([HVO4]2-). For decavanadate, three shifts are observed in accord with the number of nonequivalent sites: −422, −502, −519.
References
Nuclear magnetic resonance
Vanadium | Vanadium-51 nuclear magnetic resonance | [
"Physics",
"Chemistry"
] | 305 | [
"Nuclear chemistry stubs",
"Nuclear magnetic resonance",
"Nuclear magnetic resonance stubs",
"Nuclear physics"
] |
62,068,304 | https://en.wikipedia.org/wiki/Kathryn%20Beers | Kathryn L. Beers is an American polymer chemist. Beers is Leader of the Polymers and Complex Fluids group in the Materials Science and Engineering Division at the National Institute of Standards and Technology. Her research interests include microreactors and microfluidics, advances in polymer synthesis and reaction monitoring, macromolecular separations, integrated and high throughput measurements of polymeric materials, degradable and renewable polymeric materials, and sustainable materials.
Early life and education
Beers is a native of the Washington metropolitan area. She completed a B.S. in chemistry at the College of William & Mary in 1994. Her Honors College undergraduate thesis was titled The effects of deuteration of ferromagnetic properties: a study of single crystal Fe[S2CN(C2D5)2]2Cl. In 1996, she earned an M.S. in polymer science at Carnegie Mellon University. She completed a Ph.D. in chemistry at Carnegie Mellon in 2000. She worked with professor Krzysztof Matyjaszewski. Her dissertation was titled Design, synthesis and properties of comb copolymers with variable grafting density by controlled radical polymerization. From 2000 to 2002, she was a National Research Council postdoctoral fellow in the Polymers Division at the National Institute of Standards and Technology (NIST).
Career
From 2002 to 2007, Beers was a research chemist and project leader in the polymer formulations at the NIST Combinatorial Methods Center (NCMC) in the Polymers Division at NIST. Beers was the Assistant Director for Physical Sciences and Engineering in the Office of Science and Technology Policy (OSTP) from 2007 to 2008. While at OSTP, Beers oversaw a portfolio including the Office of Science, Science Mission Directorate, and portions of the National Science Foundation. She worked to coordinate inter-agency and international cooperation and interaction with the physical science field. She was the director of the NIST Combinatorial Methods Center (NCMC) from 2008 to 2009. From 2008 to 2012, she was a Project Leader of the Renewable Polymers project, and Group Leader of the Sustainable Polymers Group. Since 2013, Beers serves as Group Leader of the Polymers and Complex Fluids group in the Materials Science and Engineering Division at NIST.
Beers became a member of the American Chemical Society (ACS) in 1993. She has served as secretary of the ACS Division of Polymer Chemistry and served in the POLY Chair series from 2012 to 2017. She became a member of the Materials Research Society in 2001 and Sigma Xi in 2004. She is also a member of the American Institute of Chemical Engineers.
Research
Beers researches microreactors and microfluidics, advances in polymer synthesis and reaction monitoring, macromolecular separations, integrated and high throughput measurements of polymeric materials, degradable and renewable polymeric materials, and sustainable materials.
Awards and honors
In 2005, Beers was awarded the Department of Commerce Silver Medal. She was a 2006 Department of Commerce Science and Technology Policy (ComSci) fellow. In 2007, she received the Presidential Early Career Award for Scientists and Engineers.
References
External links
Living people
21st-century American chemists
American women chemists
20th-century American chemists
National Institute of Standards and Technology people
Women materials scientists and engineers
American materials scientists
College of William & Mary alumni
Carnegie Mellon University alumni
Office of Science and Technology Policy officials
Polymer scientists and engineers
Year of birth missing (living people)
21st-century American women scientists | Kathryn Beers | [
"Materials_science",
"Technology"
] | 696 | [
"Women materials scientists and engineers",
"Materials scientists and engineers",
"Women in science and technology"
] |
62,069,340 | https://en.wikipedia.org/wiki/De%20Brouckere%20mean%20diameter | The De Brouckere mean diameter is the mean of a particle size distribution weighted by the volume (also called volume-weighted mean diameter, volume moment mean diameter. or volume-weighted mean size). It is the mean diameter, which is directly obtained in particle size measurements, where the measured signal is proportional to the volume of the particles. The most prominent examples are laser diffraction and acoustic spectroscopy (Coulter counter).
The De Brouckere mean is defined in terms of the moment-ratio system as,
Where ni is the frequency of occurrence of particles in size class i, having a mean Di diameter. Usually in logarithmic spaced classes, the geometric mean size of the size class is taken.
Applications
The De Brouckere mean has the advantage of being more sensitive to the larger particles, which take up the largest volume of the sample, therefore giving crucial information about the product in the mining and milling industries. It was also used in combustion analysis, as the D[4,3] is less affected by the presence of very small particulate residuals, which enabled the evaluation of the primary diesel spray.
Further reading
See also
Sauter mean diameter
References
Fluid dynamics | De Brouckere mean diameter | [
"Chemistry",
"Engineering"
] | 240 | [
"Piping",
"Chemical engineering",
"Fluid dynamics stubs",
"Fluid dynamics"
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62,072,493 | https://en.wikipedia.org/wiki/Chloroflexus%20islandicus | Chloroflexus islandicus is a photosynthetic bacterium isolated from the Strokkur Geyser in Iceland. This organism is thermophilic showing optimal growth at 55 °C (131 °F) with a pH range of 7.5 – 7.7. C. islandicus grows best photoheterotrophically under anaerobic conditions with light but is capable of chemoheterotrophically growth under aerobic conditions in the dark. C. islandicus has a yellowish green color. The individual cells form unbranched multicellular filaments about 0.6 μm in diameter and 4-7 μm in length.
Phenotypic characteristics
As a genus, Chloroflexus spp. are filamentous anoxygenic phototrophic (FAP) organisms that utilize type II photosynthetic reaction centers containing bacteriochlorophyll a, and light-harvesting chlorosomes containing bacteriochlorophyll. Beta- and gamma-carotenes are present. C. islandicus is gram negative. Cell morphology shows the presence of chlorosomes, pili and gliding motility. Pili are unique to C. islandicus being the only organism in the Chloroflexus genus to possess pili.
Genetic characteristics
The whole genome sequence of Chloroflexus islandicus was able to be determined (5.14 Mb). Using the 16S rRNA gene analysis, ANI (Average Nucleotide Identity) and DDH (DNA-DNA Hybridization) a new species of Chloroflexus was confirmed. The 16S rRNA analysis showed it is closely related to Chloroflexus aggregans (97.0%). The genomic data revealed 84.1% ANI and 22.8% DDH for Chloroflexus islandicus strain vs other known Chloroflexus strains. The separated species based on ANI is 95.0% or less and DDH is 70.0% or less. The G/C content for Chloroflexus islandicus was found to be 59.6 mol%.
See also
Chloroflexota
Endosymbiotic theory
References
Phototrophic bacteria
Bacteria described in 2017
Chloroflexota | Chloroflexus islandicus | [
"Chemistry",
"Biology"
] | 488 | [
"Bacteria",
"Photosynthesis",
"Phototrophic bacteria"
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62,073,057 | https://en.wikipedia.org/wiki/Space%20Weather%20Follow%20On-Lagrange%201 | Space Weather Follow On-Lagrange 1 (SWFO-L1) is a future spacecraft mission planned to monitor signs of solar storms, which may pose harm to Earth's telecommunication network. The spacecraft will be operated by the National Oceanic and Atmospheric Administration (NOAA), with launch scheduled for no earlier than September 2025. It is planned to be placed at the Sun–Earth Lagrange point, a location between the Earth and the Sun. This will allow SWFO-L1 to continuously watch the solar wind and energetic particles heading for Earth. SWFO-L1 is an ESPA Class Spacecraft, sized for launch on an Evolved Expendable Launch Vehicle Secondary Payload Adapter (ESPA) Grande ring in addition to the rocket's primary payload. The spacecraft's Solar Wind Instrument Suite (SWIS) which includes three instruments will monitor solar wind, and the Compact Coronagraph (CCOR) will monitor the Sun's surroundings to image coronal mass ejection (CME). A CME is a large outburst of plasma sent from the Sun towards interplanetary space.
Together with space weather observation capabilities on the Earth-orbiting GOES-U satellite, SWFO-L1 constitutes the space segment of NOAA's Space Weather Follow On (SWFO) program. The aim of the SWFO program is to ensure the robust continuity of space-based measurement of the critical space weather environment. All of the spacecraft located in which are currently monitoring CMEs and the solar wind have operated beyond their design lifetime. SWFO-L1 SWIS instruments will replace ACE's and DSCOVR's monitoring of solar wind, energetic particles and the interplanetary magnetic field while CCOR will replace SOHO's LASCO (Large Angle and Spectrometric Coronagraph) imaging of CMEs.
Command and control system
On 5 February 2021, NOAA awarded the SWFO-L1 Command and control contract to L3Harris in Melbourne, Florida. The contract has a total value of US$43.8 million, with a five-year performance period. The SWFO-L1 mission is planned to launch as a rideshare with NASA's Interstellar Mapping and Acceleration Probe (IMAP). The contractor is responsible for up to two years of operations support. This will be accomplished by adding the capability to the existing Geostationary Operational Environmental Satellite-R Series Core Ground System.
NOAA manages the contract. In addition to work at L3Harris' facility in Melbourne, the contractor will install equipment at the NOAA Satellite Operations Facility (NSOF) in Suitland, Maryland; NOAA's Wallops Command and Data Acquisition Station (WCDAS) in Wallops, Virginia; and at NOAA's Consolidated Backup Facility (CBU) in Fairmont, West Virginia.
The work will allow SWFO-L1 to provide continuity of solar wind and coronal mass ejection imagery data from the Lagrange-1 point to NOAA's National Weather Service Space Weather Prediction Center in Boulder, Colorado. These data are critical to support monitoring and timely forecasts of space weather events that have the potential to adversely impact elements vital to national security and economic prosperity, including telecommunication and navigation, satellite systems and the power grid. NOAA is responsible for overall implementation and funding of the SWFO program. The program is managed as an integrated NOAA-NASA program, where NASA serves as NOAA's acquisition agent for the space segment and for launch services. NOAA is responsible for the ground segment including the acquisition, development, test and integration of the SWFO Command and control system.
Instruments
In April 2020, Southwest Research Institute (SwRI) was awarded a contract to supply SWFO-L1's magnetometer instrument.
On 1 July 2020, on behalf of NOAA, NASA awarded the SWFO-L1 Solar Wind Plasma Sensor (SWiPS) contract to Southwest Research Institute (SwRI) in San Antonio, Texas. SwRI was awarded a contract with a total value of US$15.6 million. The period of performance is 76 months. SWFO-L1 will provide NOAA with the continuity of solar wind data and coronal mass ejection imagery, the National Weather Service's highest priority for space weather observations. University of California, Berkeley was awarded US$7.5 million for the development of the Supra-Thermal Ion Sensor (STIS). The SWFO-L1 satellite, which is planned to launch as a rideshare with the NASA Interstellar Mapping and Acceleration Probe (IMAP), will collect upstream solar wind data and coronal imagery to support NOAA's mission to monitor and forecast space weather events. NOAA is responsible for the Space Weather Follow On program. NASA is the program's flight system procurement agent, and NASA's Goddard Space Flight Center in Greenbelt, Maryland, is the lead for this acquisition.
Launch
Space Weather Follow On-Lagrange 1 is planned to be launched as a secondary payload on the SpaceX Falcon 9 launch vehicle carrying NASA's Interstellar Mapping and Acceleration Probe (IMAP) spacecraft. As of December 2024, the launch is scheduled for no earlier than September 2025.
References
External links
Space Weather Follow On-L1 mission
Solar space observatories
2025 in spaceflight | Space Weather Follow On-Lagrange 1 | [
"Astronomy"
] | 1,096 | [
"Space telescopes",
"Solar space observatories"
] |
62,073,693 | https://en.wikipedia.org/wiki/Paper-based%20biosensor | Paper-based biosensors are a subset of paper-based microfluidics used to detect the presence of pathogens in water. Paper-based detection devices have been touted for their low cost, portability and ease of use. Its portability in particular makes it a good candidate for point-of-care testing. However, there are also limitations to these assays, and scientists are continually working to improve accuracy, sensitivity, and ability to test for multiple contaminants at the same time.
History
Paper has been used in analytical chemistry as far back as the 1800s, when litmus paper was first reported, and has since been used for techniques such as paper chromatography and lateral flow assays. However, it was only identified as a material for microfluidic assays in 2007, when patterned paper was proposed as a low-cost platform for bioassays.
Varieties of paper-based biosensors
A number of paper-based biosensors have been developed, which use a variety of approaches. In general, pathogens are detected via colorimetric, electrochemical, fluorescent, and chemiluminescent detection, though there are other types of sensors as well. Several examples of paper-based biosensors are described below.
For general bacterial detection
One device that has been described as being capable of detecting bacterial presence in water samples uses the common property of oligosaccharides and monosaccharides present on the surface of bacterial cells. It is an electrochemical device which uses hydrophobic paper that has been imbedded with carbon electrodes. Instead of using antibodies as the detectors, which are expensive, this device uses Concanavalin A (Con A), which is highly specific to the oligosaccharides and monosaccharides. The Con A is attached to the carbon electrodes, which are also equipped with carboxyl groups. The presence of bacteria triggers a series of electrochemical reactions, which are measured using a device called a potentiostat. This device is less sensitive than some others, with a detection limit of 1.9 × 103 CFU/mL. By comparison, some ELISAs range from 20 CFU/mL to 1 x 104 CFU/mL.
For detecting E. coli
Detection via bacteriophage
Multiple paper devices have been reported for the detection of E. coli specifically in water samples. One such device utilizes a recombinant version of the T4 bacteriophage which carries the gene for β-galactosidase. Water samples are filtered using membrane filters, then the filter papers are placed into the paper-based device which contains nutrient medium. They are then incubated for 4 hours at 37 °C. Next, the bacteriophage and the β-galactosidase indicator substrate are added to the sample. This causes the cells to lyse and release the β-galactosidase enzyme, which triggers the conversion of the substrate into a fluorescent product, indicative of the presence of the pathogen. Fluorescence is detected using a luminescence imaging device. The device was found to be highly specific to E. coli, and was tested against the presence of Enterobacter cloacae, Aeromonas hydrophila, and Salmonella Typhimurium. It has a detection limit of less than 10 CFU/mL, which is considered quite sensitive.
Detection via blotting paper
Another device, called DipTest, has also been developed to detect E. coli. It utilizes porous cellulose blotting paper. One end of the paper strip is coated in a hydrophobic material, while the other is coated with a chemoattractant - a substance which attracts cells based on their chemical properties. At the hydrophobic end, customized chemical reagents are imbedded in the paper in a reaction zone. The paper is dipped in the water sample, and if E. coli is present, it will be attracted to the chemoattractant at one end of the paper. The bacterial cells will then move up the paper via capillary action, and once it reaches the reaction zone, it reacts with the reagents to produce a pink to red color.
For detecting Salmonella
One paper-based biosensor that can be used to detect Salmonella, as well as E. coli, uses the nanomaterial graphene. These strips are a form of lateral flow assay, where the test line is composed of fluorescence antibody-labeled CdSe/ZnS quantum dots (Ab-QDs) as probes. After the sample has been applied, graphene oxide is added and it functions as the revealing agent. An energy transfer takes place between a donor molecule and an acceptor molecule. When no Salmonella is present, the Ab-QDs function as the donor, with graphene being the acceptor, and the fluorescence of the test line is quenched by this energy transfer. The presence of Salmonella, on the other hand, allows for fluorescence because of the manner in which the bacterial cells bind to the Ab-QDs: the distance between the donor and acceptor is too large to allow for the energy transfer, and thus fluorescence is not quenched. The strips have a detection limit of 100 CFU/mL.
Applications
Context
Annually, over 1.6 million people die as a result of pathogens from contaminated water. In the developing world, 2,200 children die per day from waterborne diseases. Per World Health Organization (WHO) standards, for water to be considered clean enough for drinking, bacteria should be undetectable in any 100 mL sample. The primary contaminants of water are pathogens, such as the bacteria Campylobacter, Clostridium, Salmonella, Staphylococcous, Anabaena, Microcystis, worms such as Schistosoma mansoni, and Taenia saginata, protozoans such as Entamoeba histolytica and Giardia duodenalis, and viruses and fungi such as enteroviruses and microsporidia. Outbreaks of waterborne diseases, such as cholera, have affected millions in the 19th and 20th centuries over the course of several pandemics, usually as a result of inadequate wastewater treatment systems and general sanitation. This is not a problem of decades past, however. As recently as 2015, it was found that 1.3 billion people are at risk for cholera annually, with 2.86 million annual cases and an estimated 95,000 deaths. Cholera is just one example of waterborne disease, however, and more broadly, 780 million people worldwide still lack access to clean drinking water.
Benefits
Traditional methods for detecting contamination in water, though highly accurate and sensitive, pose a number of obstacles. They are often costly, require the operation of a trained technician, and are labor intensive. They can also be time consuming, for example, microbiological assays necessitate growing and isolating the pathogen from the sample, which can take several days or even weeks, in addition to preparing media. Paper-based biosensors address many of these problems. Specifically, paper as a material has several benefits. No external power is required, as the sample travels through the device via capillary action. Its fiber network structure allows for the storage of the necessary reagents in an active form. It is also cost-effective, has a high surface area to volume ratio, absorbs the sample efficiently, and is easily disposable by incineration.
In general, settings with limited resources could benefit from low-cost, easy to use, on-site, and rapid testing of water samples. In addition, there is a need for home-care testing. Widespread distribution of adequate but low-cost diagnostic devices, such as paper-based biosensors, could potentially alleviate disease burden. Beyond that, it could also result in more accurate epidemiological case data which could improve disease models.
Limitations
The most significant limitation of this technology is its sensitivity, in other words, its ability to detect very low levels of a contaminant in the sample. Some of the most sensitive ELISAs can detect contaminants at levels as low as 20 CFU/mL. In addition to improving accuracy - the correct identification of a particular pathogen - another challenge is developing biosensors which can readily distinguish between types of pathogens. Finally, the material of paper itself, while it offers many benefits, has some drawbacks, too. For example, there is a limit to how well paper devices can control the rate and direction of flow of the sample. This introduces limitations regarding the handling of complex chemical compounds or managing multistep assays, depending on the biosensor in question.
References
Microfluidics | Paper-based biosensor | [
"Materials_science"
] | 1,819 | [
"Microfluidics",
"Microtechnology"
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62,074,849 | https://en.wikipedia.org/wiki/Crestron%20Electronics | Crestron Electronics (or simply Crestron) is an American privately held multinational corporation that manufactures and distributes control automation and integration technology. The company designs, manufactures, and distributes equipment used to control technology in commercial audiovisual environments such as meeting spaces, conference rooms, classrooms and auditoriums. Crestron equipment is also used for high-end residential audiovisual installations, built on the company's Crestron Home OS.
History
Crestron was founded by George Feldstein in 1972. After graduating from New York University with a master's in electronic engineering, Feldstein worked as chief engineer at a firm that built industrial control and testing equipment. He left in 1969 to start his own business. He began by cold-calling other businesses, offering to build or repair their equipment. His company's first job was for Colgate-Palmolive, building a device to help automated assembly lines put the right amount of powder into boxes of detergent. An early milestone was the company's development of a wireless remote for commercial audiovisual systems, which led to work developing audio switches, video projectors, and lighting control panels, and selling integrated audiovisual systems to businesses and universities.
After George Feldstein's death in 2014, Randy Klein was named Crestron's CEO and president. In December 2021, Klein retired, and Dan Feldstein took over as CEO and president. In May 2022, Crestron unveiled the company's engineering base, the George Feldstein Technology Center in Rockleigh.
Crestron Certification began in 1998, which evolved into the Crestron Masters program in 2001. Crestron Masters is an annual certification and training event where programmers, technology architects, and systems designers are trained in the latest Crestron technology, industry best practices, and distribution strategies, with various levels of certification offered.
Originally headquartered in Cresskill, New Jersey, Crestron is now headquartered in Rockleigh, New Jersey, with over 90 offices worldwide.
Products
The company does not sell its products directly, instead using a network of dealers and integrators to sell products to end users. Crestron equipment can be found in homes, offices, universities, government buildings, churches, and healthcare facilities worldwide.
The company offers commercial business solutions for enterprise, education, and government, including conference room technology, video distribution, XiO cloud management software, and network security. One such offering is Crestron Flex, a line that integrates video conferencing, wireless presentation, and smart room control. Crestron has been noted for envisioning "the workplace of the future," helping to design workspaces for companies including Meta, Microsoft, and Johnson & Johnson.
The company also offers technology solutions for residential, hospitality, marine, and multi-dwelling units industries using their own operating system, Crestron Home OS. Crestron Home is used to configure and control home automation devices. It integrates with Amazon Alexa, Siri, and Google Home. Crestron Home OS can be customized for each homeowner, based on user preferences.
Mark Zuckerberg's smart home technology, Jarvis, is built on top of smart home technology by Crestron. It uses Crestron to provide a way for Jarvis's app to speak to lights, thermostats, and doors.
Starting in 2016, Crestron donated audiovisual and automation technology to Orbis International's Flying Eye Hospital, an eye care hospital located onboard an aircraft that flies to underserved areas to treat patients at risk of losing their sight. The Crestron technology helps enable staff to operate on these patients and gives local doctors the opportunity to be trained in a classroom onboard the plane. It is the world's first such hospital.
Crestron Electronics hosted its Modern Work Summit on latest workplace trends at the Madrid Marriott Auditorium Hotel and Conference Center in Spain on May 23 and 24, 2023, and featured presentations from Microsoft, Zoom and Gensler.
Acquisitions
Crestron announced partnerships with Huddly in 2017 and with Shure and Jabra in 2021. In 2022, Crestron acquired 1 Beyond, a video technology company.
References
Companies based in Bergen County, New Jersey
Rockleigh, New Jersey
Home automation companies | Crestron Electronics | [
"Technology"
] | 858 | [
"Home automation",
"Home automation companies"
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62,074,925 | https://en.wikipedia.org/wiki/Borel%20subalgebra | In mathematics, specifically in representation theory, a Borel subalgebra of a Lie algebra is a maximal solvable subalgebra. The notion is named after Armand Borel.
If the Lie algebra is the Lie algebra of a complex Lie group, then a Borel subalgebra is the Lie algebra of a Borel subgroup.
Borel subalgebra associated to a flag
Let be the Lie algebra of the endomorphisms of a finite-dimensional vector space V over the complex numbers. Then to specify a Borel subalgebra of amounts to specify a flag of V; given a flag , the subspace is a Borel subalgebra, and conversely, each Borel subalgebra is of that form by Lie's theorem. Hence, the Borel subalgebras are classified by the flag variety of V.
Borel subalgebra relative to a base of a root system
Let be a complex semisimple Lie algebra, a Cartan subalgebra and R the root system associated to them. Choosing a base of R gives the notion of positive roots. Then has the decomposition where . Then is the Borel subalgebra relative to the above setup. (It is solvable since the derived algebra is nilpotent. It is maximal solvable by a theorem of Borel–Morozov on the conjugacy of solvable subalgebras.)
Given a -module V, a primitive element of V is a (nonzero) vector that (1) is a weight vector for and that (2) is annihilated by . It is the same thing as a -weight vector (Proof: if and with and if is a line, then .)
See also
Borel subgroup
Parabolic Lie algebra
References
.
.
.
Representation theory
Lie algebras | Borel subalgebra | [
"Mathematics"
] | 383 | [
"Representation theory",
"Fields of abstract algebra",
"Algebra stubs",
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62,075,453 | https://en.wikipedia.org/wiki/1-Deoxysphingolipids | The 1-deoxysphingolipids (1-deoxySLs) are an atypical and recently discovered class of sphingolipids (SLs). They are formed during the nove synthesis pathway and their essential C1-OH deficit causes the malfunctions of the following transformations to achieve complex sphingolipids. In general, sphingolipids are formed during a reaction that is catalyzed by the SPT enzyme (serine-palmitoyltransferase) where the condensation of serine and palmitoyl-CoA takes place. The origin of this rare sphingolipid, though, is due to a defect of the SPT which can also use (as substrats) alanine or glycine. This change is what forms the 1-deoxySL.
1-deoxysphingolipids cannot be degraded over the canonical catabolic pathways leading to high 1-deoxySL levels that are involved in several neurological and metabolic disorders.
Structure
There are two types of 1-deoxySLs: 1-deoxysphinganine and 1-deoxymethylsphinganine.
1-Deoxysphinganine
It is an amino alcohol and a bioactive sphingoid. Its distinctive trait is that the terminal hydroxy group has been replaced by hydrogen. It possesses antineoplastic properties, appearing to inhibit the proliferation of some kinds of cancer.
This sphingoid base can be found, in general, in low levels, in animal cells, and at higher concentrations in the cell membranes of certain bacteria, including Bacteroides species common to the animal gut microbiome—suggesting this as a potential source of these compounds in circulation. It was found for the first time in a marine organism, in which context it is known as spisulosine. It is known by other names such as ES-285.
The molecular weight of this compound is 285,5 g/mol and its molecular formula is C18H39NO, which means it has 18 carbons.
1-Deoxymethylsphinganine
It is a bioactive sphingoid which derives from the sphinganine. It is formed by a sphingoid and an amino alcohol and it constitutes the conjugated base of 1-deoxymethylsphinganine (1+). Its role is accepting a hydron from a donor via its organic amino compound; it is a Brønsted base.
It is also known as deoxymethyl-SA, (2R)-1-aminoheptadecan-2-ol and 1-desoxymethylsphinganine.
The molecular weight of this compound is 271,48 g/mol and its molecular formula is C17H37NO, which means it has 17 carbons.
In relation to its appearance, it has a powder form. Other physical and chemical properties are not certainly known.
Localization
Sphingolipid metabolism is based in compartmentalization. In this way, possible cycles of opposite anabolism and catabolism reactions are avoided.
The ER is the compartment where the synthesis of ceramide is produced. Then, it will move to the Golgi apparatus. If the ceramide transporter protein is involved, it will go to the TGN to form sphingomyelin. If the vesicles are the ones in charge of transport, it will reach the cis zone to become glucosylceramide.
Instead, deoxySL transport and localization in cells is not known for sure. It is true that several studies has proved some of his intracellular behaviours.
What allows to understand the distribution in the cell of 1-deoxysphingolipids is the comparison between the behavior of fluorescent analogs of the SLs (C6-NBD-(dh)-Cer) and the 1-deoxySLs (C6-NBD-deoxy(dh)-Cer). The fact that C6-NBD-deoxy(dh)-Cer is not located in the same compartments as C6-NBD-(dh)-Cer indicates that the absence of C1-OH interferes in the protein and vesicular traffic.
On the other side, it's been found that 1-deoxySLs gave a signal in the mitochondria and remained prominent by using alkyne-1-deoxySA, as well as the co-location in the RE and Golgi markers. The signal was absent in the lysosomes and in the plasma membrane.
A specific change in 1-deoxySLs causes variations in mitochondrial morphology, as well as variations of the same type in the RE when de concentrations are toxic.
Metabolism
Synthesis
1-DeoxySLs has a similar pattern to sphingolipids during de novo synthesis. The reaction is catalyzed by the enzyme serine palmitoyltransferase (SPT) but instead of condensing palmitoyl-CoA and L-serine, the amino acid substrate is replaced by L-alanina or L-glycine.
This atypical sphingolipids are formed as the result of a mutated SPT (SPTLC1/SPTLC2) with alternative activities. It has also produced by wild-type of SPT under unfavorable conditions where the synthesis of L-serine is diminished and / or the biosynthesis of alanine and glycine is too high.
The result of the reaction with L-alanine forms 1-deoxysphinganine (1-deoxySA; m18:0), while the use of glycerin forms 1-deoxymethylsphinganine (1-deoxymethylSA; m17:0). Both molecules are 1-deoxySLs.
Degradation
Atypical sphingolipids' lack of C1-OH (hydroxyl group) of sphinganine its the cause they accumulate in the cytoplasm and cannot be degraded. These headless sphingolipids are not able to be phosphorylated and they can neither converted into complex lipids as sphingomyelins and glycosphingolipids (galactosylceramides, gangliosides, cerebrosides ...). Instead, they have toxic effects to the cell.
Despite previous opinions that 1-deoxySLs are dead-end metabolites, new researches prove the opposite. Its concentrations decrease over time because atypical sphingolipids convert into downstream products, which normally are polyunsaturated and polyhydroxylated. The main reason for this transformation is detoxification. The enzymes involved in this process produce the change within several days, making it a slow conversion. This take places in two stages:
Firstly, the hydroxylation of compounds begins by cytochrome P450 enzymes.
Secondly, hydrophilic moieties join up to the compounds in order to increase water solubility. As a result, the excretion through urine occurs and compounds can be removed.
Either CYP4A or CYP4F are the enzymes involved in the downstream metabolism of 1-deoxySLs. It is not yet known which one takes place in the process but, it is more likely to be CYP4F as in mouse experiments this enzyme is responsible for 1-deoxySLs formation.
Physico-chemical properties
Nowadays there is not much information about the properties of 1-deoxysphingolipids. However, there have been some studies that demonstrate some important facts. This data is still not proven to be the same in each 1-deoxysphingolipids but, until then, we extrapolate with caution in order to keep investigating and gathering more information.
The biggest two structural properties that differ from the canonical sphingoid bases are the lack of C1-OH and the double bond position. The missing C1 hydroxyl group is a decisive characteristic that influences in the molecule's interactions, as its ability to form intra and intermolecular H-bond networks decreases. On the other hand, the lack of the double bond interferences in the main transition temperature.
These characteristics are thought to make a big impact on the membrane biophysical properties as well as the integrity. The hydrophobicity and the main transition temperature of these lipids play an important role on the structure and physico-chemical properties of biological membranes. These both differences disrupt the setting up with other lipids and as a result, the capacity to segregate into tightly packed gel domains is put in risk.
Function
Up until now, sphingolipids functions have not been yet known. In any case, its danger contributes to the development of several neuropathies and diseases.
Toxicity
There are some diseases which causes are due to the formation of 1-deoxySLs and doxSA. For example, HSAN1 is caused because of the formation of this atypical and neurotoxic sphingolipid metabolites (doxSA and 1-deoxySLs). Moreover, it has been found that pacients with type 2 diabetes, autonomic neuropathy type 1 (HSAN1) and hereditary sensory have elevated number of this kind of sphingolipids in their plasma. There are some investigations that affirm that plasma concentrations in patients with diabetes or the metabolic syndrome were higher than the control group's concentrations. The increase of 1-deoxySLs in metabolic disorders is curiously related to a fatty acid and carbohydrate metabolic dysregulation, that also affects to L-serine metabolism.
We are capable to synthesize an alkyne analog of 1- deoxysphinganine (doxSA), which is the metabolic precursor of all deoxySLs. This is useful for us in order to trace the metabolism of deoxySLs. With this information, now we are able to know that the metabolism of this lipids is restricted to only some lipid species.
Considering the fact that we do not know much of the 1-deoxySL, there are some investigations that try to find a possible treatment for the diseases caused by this sphingolipid. In some of the experiments, there are hypothesis about a possible diabetic neuropathy treatment. This one consists in an oral L-serine supplementation since it has been demonstrated that this substance lowered 1-deoxySL concentrations in plasma.
References
Lipids | 1-Deoxysphingolipids | [
"Chemistry"
] | 2,226 | [
"Organic compounds",
"Biomolecules by chemical classification",
"Lipids"
] |
62,075,617 | https://en.wikipedia.org/wiki/AZ64 | AZ64 or AZ64 Encoding is a data compression algorithm proprietary to Amazon Web Services.
Amazon claims better compression and better speed than raw, LZO or Zstandard, when used in Amazon's Redshift service.
References
Amazon Web Services
Lossless compression algorithms | AZ64 | [
"Technology"
] | 55 | [
"Computing stubs"
] |
62,075,767 | https://en.wikipedia.org/wiki/Anatomical%20model | An anatomical model is a three-dimensional representation of human or animal anatomy, used for medical and biological education.
Model specs
The model may show the anatomy partially dissected, or have removable parts allowing the student to remove and inspect the modelled body parts. Some models may have changeable genital inserts and other interchangeable parts which permit a unisex model to represent an individual of either sex.
Although 3D computer models of anatomy now exist as an alternative, physical anatomical models still have advantages in providing insight into anatomy.
See also
Anatomy
Comparative anatomy
References
External links
Physical models
model
Medical education
History of anatomy
Sculpture | Anatomical model | [
"Physics",
"Biology"
] | 126 | [
"Anatomy",
"Physical objects",
"Physical models",
"Matter"
] |
62,075,876 | https://en.wikipedia.org/wiki/Ilfracombe%20Iron%20Company | The Ilfracombe Iron Company (I.I.C.) was an iron mining and smelting company that operated in Northern Tasmania in 1873 and 1874. The company's operations included a blast furnace, ore mine, water wheel, village, and jetty. The I.I.C. rebuilt a disused timber-haulage tramway, terminating at Ilfracombe—now the southern part of modern-day Beauty Point—which it extended at both ends to reach its iron ore mine and its jetty. The ruin of its blast furnace is significant, as one of the only three such ruins of 19th-Century iron-smelting blast furnaces in Australia and the only one in Tasmania. It is the only remaining ruin—in Australia—of a 19th-Century blast furnace that had an iron shell.
Iron ore from the company's mine was smelted at a foundry in Melbourne in 1873. Two bells were cast from this iron; the smaller one was exhibited at the Victorian Exhibition (1872–73) in Melbourne and the larger bell at the Vienna Exposition of 1873.
The company constructed a blast furnace alongside a tributary of Middle Arm Creek. It originally intended to power the blast machinery from a large water wheel, which was erected but not used. Despite several design iterations, the steam-powered blast machinery was severely under-sized. Before this situation could be rectified, by raising more capital, the Oriental Bank foreclosed. The assets were sold cheaply; possibly, the new owner intended to restart operations. However, a large fall in the price of iron seems to have ended that possibility.
It remains questionable that the blast furnace actually produced any pig iron, although the company announced in an ambiguous telegram that it had.
Historical context
Soon after the first settlement in Northern Tasmania, at York Town in 1804, colonial settlers found that there were extensive deposits of iron ore in the hills to the west of the Tamar estuary. Interest in the area was aroused again by the report in 1866 of the Government Geologist, Charles Gould.
There was an increase in pig-iron prices in the early 1870s, which led to the formation of a number of colonial era iron-making ventures in Australia. The price of imported pig-iron increased, from £4 10s per ton in 1870 to £9 per ton in 1873 greatly advantaging locally manufactured iron. However, this high price did not last long, as iron-making capacity increased and pig-iron was once again imported cheaply as ballast in sailing ships returning from England to Australia.
The Ilfracombe Iron Company was one of four ventures that smelted iron from local iron ore, in Tasmania during the 1870s; the others were, the British and Tasmanian Charcoal Iron Company, the Tamar Hematite Iron Company—both nearby on the Tamar estuary—and the Derwent Iron Company. A fifth venture, the Swedish Charcoal Iron Company never went beyond issuing a prospectus. There were also three commercial iron-smelting operations in mainland Australia during the 1870s, the Fitzroy Iron Works, the Lal Lal Iron Company, and the Lithgow Valley Iron Works.
Smelting materials
The ore deposit was the first of the deposits in the West Tamar area that were mentioned by Charles Gould in his report of 1866. It was located on private property at on a tributary of Middle Arm Creek, on the western flank of Peaked Hill, about 5 km south of the modern-day town of Beaconsfield. The company later located its smelting site adjacent to this deposit.
A sample, consisting of "hematite and brown ore", had the following analysis:
"Iron ......... 60.6 [%]
Silica ........ 2.4 [%]
Sulphur and phosphorus, though carefully sought for were not detected."
Limestone was obtained from deposits nearby. The fuel used was charcoal, burnt from local timber.
History of operations
Foundation of the company
The force behind the new company was Captain Duncan Longden. The other major shareholders were Ayde Douglas (a Tasmanian lawyer and politician, who was also an owner of a previous, then dormant timber venture in the same area), James Major (of the Melbourne engineering firm Doyne, Major and Willet), James Bickerton, John Robb, David Spence, and two others.
The company was at work for some time before it was officially registered. During this period, it was mainly Longden and Major who were active. The two secured a 3,000 acre leasehold in 1872.
The Ilfracombe Iron Company was registered on 28 January 1873. It had an authorised capital of £50,000 in 10,000 £5 shares. 2000 of the shares were issued as fully paid, probably in exchange for properties, assets and services that the new company needed. The remaining shares were partly paid, to £4.
Trial smelting and exhibition castings
Before the Ilfracombe Iron Company was even registered, it had sent iron ore to Melbourne for a trial smelting, at the Railway Foundry, owned by Drysdale and Fraser. In November 1872, the iron ore was smelted with coke and limestone in a furnace—probably a cupola furnace—and various castings were made, including two bells, seven 'pigs' weighing 2-stone (12.7 kg) and one pig weighing 3-hundredweight (152 kg), and "half-a-dozen 18lb. [8.2 kg] cannon balls". It seems that a total of around 400 kg of iron was made, the first time that Tasmanian iron ore had been smelted in a significant quantity in Australia.
The smaller bell—weighing about 9 kg—was exhibited at the Victorian Exposition of 1872-1873. The larger bell—about 2 feet high, 18 inches wide at mouth, and weighing 210 lbs (95 kg)—was exhibited at the Vienna Exposition of 1873, where it was inspected in September 1873 by Emperor Franz Joseph. It had the coat of arms of Melbourne on one side and, along the rim on the other side, the words "Ilfracombe Iron Company". The ability to cast bells directly from the pig-iron demonstrated its quality.
Construction
The on-site manager was a civil engineer, Benjamin Hawkins Dodds, who had experience in the Scottish iron industry. The construction of the furnace was the responsibility of a Swedish furnaceman, Karl Haine, with the advice of James Baird Thorneycroft from Scotland.
The foundation stone of the furnace was laid on 12 May 1873, by David Spence, a Melbourne merchant, who was a shareholder. Progress was rapid, with a visitor to the site, in September 1873, reporting extensive progress, with about 100 men working at the site and the work nearly completed.
Delays
A fire was lit in the furnace in August 1873 and maintained thereafter, to dry out the furnace to be ready for production. The company prepared a pattern to cast plaques to commemorate what it planned as its first casting of pig-iron in "October 1873". The pattern still survives—held by the Queen Victoria Museum and Art Gallery in Launceston—but the casting in October never occurred.
In early November 1873, it emerged that the iron could not be run because the steam engine used to drive the blast machinery was too small. Another larger engine was on its way from Melbourne, which would be used, "till the water wheel is ready to perform the work, and will then standby to be used in time of emergency, should such arise".
Announcements of success and subsequent closure
On 24 November 1873, a small article appeared in the Melbourne newspaper The Argus. It read, " WITH reference to iron mining in Tasmania, the Launceston Examiner reports :—' A quantity of iron has been run off most successfully at the works of the Ilfracombe Iron Company. The furnace answered admirably. The company begins work with unexceptional [sic] prospects.''' " There seems to have been nothing corresponding to it, in the local press in Northern Tasmania.This would be the beginnings of the mystery surrounding the first iron production of Ilfracombe Iron Company.
A few days later, a telegram received from the manager of the I.I.C. read, "George Town, Nov. 28 Twelve pigs Ilfracombe iron shipped per Tamar. Everything progressing well." A local newspaper, the Launceston Examiner, expanded on this announcement by adding, "We believe the weight of the above is about two tons, and that the furnace was tapped on Thursday afternoon, a telegram having been sent to Mr Major that evening, asking him to arrange for shipping it by the Tamar, on her outward trip yesterday." This seemed to be incompatible with the earlier announcement in Melbourne on 24 November 1873, and appears to be the first time that success was announced in Tasmania.
Arrangements had been made to load the pigs onto the steamer Tamar, as she passed down the Tamar River from Launceston, en-route to Melbourne, on 28 November 1873. Presumably, that was done by loading the pigs at the Ilfracombe Company's jetty. It seems that James Major accompanied the pigs to Melbourne, arriving on 29 November 1873, perhaps intending show off the iron to Victorian shareholders and others.
It was soon apparent that the furnace had not stayed in service, as would be usual once production of iron had commenced.
An optimistic report appeared, on 20 December 1873, stating that production had recommenced. It was reported—presumably based on a communication with the company—that, "The new vertical iron cylinders at the Ilfracombe Iron Company's works have been completed, and found to answer admirably. The necessary repairs to the furnace have been carried out, and fire-bricks of the proper description substituted for the inferior ones which were at first unwittingly put in, and active operations were commenced last Tuesday" [16 December 1874].
However, on the same day as that report of production commencing, 20 December 1873, a prominent shareholder, Ayde Douglas, was on his way to the site to meet Major and Longden and find out for himself what was happening.
Another attempt at smelting took place on 23 December 1873, using still larger blast cylinders made of wood at the site, after which the furnace was never relit.
Demise and sale of assets
The company had exhausted its capital, wasting some of it on assets that it never put to use, such as its waterwheel. After the failure of attempts to smelt on 16 and 23 December 1873, it became apparent that a larger blast engine and larger blowing cylinders were necessary and would require more capital. The company also had a debt to the Oriental Bank.
It was decided to create a new company of larger capital, and issue new shares to existing shareholders in exchange for the old company's assets. This suited Longden and Major, who were unable to participate in any other kind of restructure, as both had run out of money by this time. However, the Oriental Bank took legal action to prevent the new company being formed and to secure repayment of its loan. An order went to the sheriff to sell off the assets.
There was no auction but the assets were sold to Ayde Douglas for £805, roughly the amount owed to the bank. Douglas had secured the assets cheaply, but the other shareholders' interests were wiped out. The waterwheel was sold off and ended up powering a stamper battery at the Leura Mine.
The low-key sale and the shunning of Major and Longden hints at conflict among the shareholders; it is likely that, as the people managing the site work and operations, Major and Longden were seen as responsible for the failure to enter production.
As the price of iron was still high at the time of the sale, Douglas probably intended to restart the works, but the iron price later collapsed. The furnace site was abandoned.
Controversy
The first hint that the Ilfracombe Iron Company may have been concealing something about the outcome of its iron smelting came in an editorial, by T.C.Just, in the newspaper the Cornwall Chronicle,(also reprinted as an article in the Tasmanian), in December 1874. It read, "It is just twelve months since we recorded the partial success of the Ilfracombe Iron Company, in smelting pig iron from the ore found on their property. We afterwards learnt, however, that this iron had not been fairly produced by any ordinary furnace process, and the subsequent collapse of the company showed this to be only too true. When attempts were made to produce the article in bulk from the large furnace, they utterly failed".
The announcement by telegram, on 28 November 1873, had merely said that, "Twelve pigs Ilfracombe iron shipped per Tamar"—making no mention of the furnace—but the obvious assumption was that the iron had come from the company's blast furnace. In any case, the day after the telegram, the pigs were on the sea en route for Melbourne; there was virtually no opportunity for locals to see the pigs before they disappeared from the district. And, unusually, the blast furnace did not remain in continuous production after its supposed first tapping.
If the twelve pigs (two tons) of iron despatched in November 1873 on the s.s. Tamar had not come from the furnace—since no other furnace was working nearby—the pigs would either be Ilfracombe iron smelted from its ore elsewhere—like the iron smelted in Melbourne in November 1872—or not Ilfracombe iron at all.
If the iron was from another source—even allowing for the relatively remote location of the blast furnace—it would have been an elaborate deception, necessitating the involvement of at least some of the company's staff and management. The unlikelihood of such a deception has led some historians to dismiss Just's editorial; one seeing it as a "political statement", by Just who was a shareholder in the rival British and Tasmanian Charcoal Iron Company.
However, four different experts—examining the furnace ruin in 1883, 1982, 1988, and 2012—failed to find any iron in the hearth of the old blast furnace. An unused cast iron tapping block from the furnace also survives; perhaps that block was a spare, but the absence of iron in the hearth is far harder to explain. It therefore seems possible that the ongoing problem with the furnace—a mismatch between the relatively small capacity of the blast machinery and the size of the furnace—was enough to prevent the furnace reaching a suitable temperature to smelt iron ore and produce molten pig-iron. If so, the well-made furnace could never have produced any iron.
Against this conclusion there is but one piece of physical evidence; an archaeological research map of the blast furnace site shows a 'bosh skull' located nearby to the furnace ruin. A bosh skull is a mass of solidified iron and slag. If it exists at the remote site, the bosh skull could only have come from the furnace. However, even this does not prove conclusively that the furnace made molten pig iron that was successfully tapped, on 27 November 1873. All that is known for certain is that the second and third attempts to smelt iron—on 16 and 23 December 1873—both failed. These were the last attempts made, because the company afterwards ran out of money.
It seems that the telegram announcement of 28 November 1873 was, most probably, part of a deliberate attempt to mislead—designed to help attract the additional capital that the company so desperately needed—as was the subsequent report of production recommencing in December 1873.
Technology
Process and equipment
Blast furnace
The furnace was an open-top, cold-blast furnace. It was described, in an article in the Launceston Examiner of 20 September 1873, as follows, "The foundation of the furnace is laid in concrete 4 feet deep, on the top of this is 6 feet 6 in. of solid substantial masonry. The masonry consists of four grand arches in the form of a cross, thus constituting a compact block 14 feet square the arches being used instead of building the block quite solid, in order to lessen the chances of the damp ascending into the body of the furnace. On the top of this masonry a large boiler plate cylinder 10 feet in diameter is erected, with a strong heavy cast iron ring at the base, from which through the masonry into the foundation holding down bolts are passed and fastened, thus firmly securing the upright cylinder." The iron shell was lined with firebricks.
The furnace had provision for conversion to recycle the off-gases to heat the blast, although no stoves to heat the blast were ever built. This suggests another probable reason for its failure; a furnace and blower possibly sized for hot-blast operation, but used as a cold-blast furnace.
A casting shed 95 feet long by 30 feet wide, with a wooden shingled roof was constructed; it was expected that casting of pig iron would occur every 12-hours.
Blast machinery
The blowing cylinders were made by Messrs Robertson Bros. of Melbourne. The equipment was described, in an article in the Launceston Examiner of 20 September 1873, as follows, "double cylinders 15 inches in diameter, 24 inches stroke, having a minimum velocity of 60 strokes per minute, and discharge the air into a large wrought iron receiver, capable of contaiting 128 cubic feet, and thence. through the tuyeres into the furnace".
The original plan was for this blast machinery would be powered by a waterwheel but in fact all actual operation of the furnace used steam power. It was powered first by a steam engine that had been hired for the purpose but proved too small. Later a larger engine was used, but it apparently it—or the blast cylinders themselves—was too small as well.
Dam and waterwheel
The plant was intended to make use of water power. A dam was constructed across Snowey's Creek, a perennial stream. The dam was about half a mile from the furnace and had a 50-foot wall. The water passed through a channel and into a flume with a fall of 97 feet. About halfway along the flume, a smaller horizontal waterwheel powered a sawmill, with the water continuing in the remaining part of the flume to the main waterwheel. After the waterwheel, the water ran through an underground passage to flow into the creek.
The waterwheel stood 120 feet from the furnace. It was 30 feet in diameter and 4 feet wide, with 64 buckets and heavy cast-iron bosses 3 feet in diameter through which the shaft passed. This large waterwheel apparently was never used by the Ilfracombe Iron Co. but was later used to power a gold mine stamper battery.
Charcoal kilns
There were two charcoal kilns, halfway between the dam and the furnace, each 200 feet long by 20 feet wide. The walls and roof were of sod, with cast-iron portholes along the sides to maintain the necessary restricted air flow for the charcoal-burning process.
Transport
Tramway
There was a disused timber tramway for the former Ilfracombe saw-mill, which conveniently ran alongside the iron ore deposit. It had been laid down in 1857 and become overgrown and rotten by the 1870s, so the track needed total reconstruction. At the river end, it needed extension to the north to the site of the new jetty.
The new tramway was horse-drawn and had wooden rails of 3-inch × 2-inch timber set at 3-foot gauge.
Jetty
The original jetty that was the terminus of the timber-haulage tramway was further south from where the I. I. C. built its new jetty. The choice of the site of the new jetty was a good one, as the new jetty could—with some extension—reach water 30 feet deep, enough to accommodate a 500 ton ship.
The jetty was described as, "a substantial jetty, 133ft long by 15ft wide" and "built of stone and logs''". The tramway ran over the length of the jetty and connected it to the smelter site.
Legacy and remnants
The ruin of the blast furnace lies on private property. It is only one of three 19th-Century blast furnace ruins in Australia, and the only one in Tasmania. It is the only such ruin with an iron outer-shell.
Approximately three metres of the lowest part of the blast furnace is still standing; the stone base and hearth—including the three tuyere ports and the three tuyere pipes—and the lowest part of the iron shell are in place. Lying on the ground, adjacent to the furnace, is the iron shell from the collapsed upper part of the furnace, which sheared off the furnace structure when a large tree fell on it. The fallen tree lay over the furnace in 1969 but is now gone. The area immediately adjacent to the furnace base is strewn with fire bricks. An unused cast iron tapping block from the old furnace survives and is on display at the Beaconsfield Mine & Heritage Centre.
The iron ore mining site is close by, as are the sites of the dam and the waterwheel, both of which can still be identified.
No trace exists of the Ilfracombe Iron Company's jetty on the Tamar River. Its former site is close to the Australian Maritime College's training facility at Beauty Point.
The pattern for plaques intended to commemorate the aborted casting of pig-iron in "October 1873" is in the Queen Victoria Museum & Art Gallery, in Launceston.
A replica of the iron bell that was shown at the Vienna Exposition of 1873 was cast in Tasmania in 2017; it is on display at the Beaconsfield Mine & Heritage Centre. On its rim, the bell has cast lettering reading "Ilfracombe Iron Company".
See also
British and Tasmanian Charcoal Iron Company
Tamar Hematite Iron Company
Lal Lal Iron Mine and Smelting Works - another 19th-Century blast furnace ruin in Victoria
Bogolong iron mine and blast furnace - another 19th-Century blast furnace ruin in New South Wales
List of 19th-century iron smelting operations in Australia
References
Companies based in Tasmania
1874 disestablishments in Australia
Defunct companies of Australia
Australian companies established in 1873
Companies disestablished in 1874
Smelting
Metal companies of Australia
Northern Tasmania
Iron mining in Australia
Energy companies established in 1873
Water wheels in Australia
Ironworks and steelworks in Australia | Ilfracombe Iron Company | [
"Chemistry"
] | 4,587 | [
"Metallurgical processes",
"Smelting"
] |
62,075,912 | https://en.wikipedia.org/wiki/Laevens%203 | Laevens 3 is a globular cluster in the constellation of Delphinus. It belongs to the Milky Way but orbits far from the centre. The cluster is named after Benjamin P. M. Laevens, the discoverer. It was first observed in 2015 using Pan-STARRS 1.
It is located 210,000 light years from Earth in the outer galactic halo. Its orbit takes it to 133,000 ly from galactic centre and out to 279,000 ly. The half light diameter is only 37 light years. The metallicity is −1.8 dex. The cluster is about 13 billion years old. The brightness is equivalent to 1,125 Suns.
References
Globular clusters
Delphinus | Laevens 3 | [
"Astronomy"
] | 149 | [
"Delphinus",
"Constellations"
] |
62,077,237 | https://en.wikipedia.org/wiki/Leaded%20copper | Leaded copper is a metal alloy of copper with lead. A small amount of lead makes the copper easier to machine. Alloys with a larger amount of lead are used for bearings. Brass and bronze alloys of copper may have lead added and are then also sometimes referred to as leaded copper alloys. Leaded copper and its alloys have been used since ancient times.
Applications
Leaded copper alloys are used to make electrical connectors and mechanical bearings, especially in the automotive industry where high performance and reliability are required. Mechanical bearings can have high lead content. Such high lead content alloys are unsuitable for welding or brazing.
Machined alloys
Alloys with around 2-4% lead are used for machined copper applications, where the lead content lubricates the copper and makes it easier to machine. These include high-quality electrical connectors where a high current capacity and low electrical resistance are required. Such connectors are used in industrial automation and the automotive industry. Brasses (copper alloyed with zinc) may also be leaded for the same reason.
Cast and sintered alloys
High-strength casting copper alloys typically contain less than 2% lead. Bearing alloys are often cast or sintered onto a steel backing. Softer alloys with a higher lead content are also used, for example in bushes where conformance to the opposite bearing surface is important.
Some casting alloys have over 20% lead content but, due to their toxicity, they are no longer used.
Toxicity
When lead alloys wear, lead is released into the environment. It is a toxic heavy metal and in recent times the use of leaded copper alloys has been reduced.
History
Signs of leaded copper use are found in the manufacture of ancient Egyptian faience. By 1500 BC leaded copper could be found across the Old World from East Asia to Africa and Europe.
Enigmatic entries in a Chinese manuscript, the Kao Gong Ji dating from around 300 BC, were deciphered by scholars in 2022, and seem to indicate that a pre-prepared copper-lead alloy named Xi may have been used in the preparation of ancient bronzes. Another copper-tin-lead alloy named Jin was also tentatively identified as a pre-prepared component of Chinese bronzes. This part of the manuscript relates to an attempt to standardise the quality of bronze manufacture.
References
Notes
Bibliography
Aalco brochure, Pages 70-85.
Jean-Marie Welter; Leaded Copper Alloys for Automotive Applications: A Scrutiny, European Copper Institute, 2014.
Copper alloys
Lead alloys | Leaded copper | [
"Chemistry"
] | 504 | [
"Copper alloys",
"Alloys",
"Lead alloys",
"Alloy stubs"
] |
62,077,323 | https://en.wikipedia.org/wiki/Dannie%20Heineman%20Prize%20%28G%C3%B6ttingen%29 | The Dannie Heineman Prize of the Göttingen Academy of Sciences and Humanities has been awarded biennially since 1961 for excellent recently published publications in a new research field of current interest. It is awarded to younger researchers in natural sciences or mathematics. The prize is named after Dannie Heineman, a Belgian-US philanthropist, engineer and businessman with German roots.
Prizewinners
1961 James Franck, biochemistry
1963 Edmund Hlawka, mathematics
1965 Georg Wittig, chemistry
1967 Martin Schwarzschild, astrophysics
1967 Gobind Khorana, biochemistry
1969 Brian Pippard, physics
1971 Neil Bartlett, chemistry
1973 Igor Schafarewitsch, mathematics
1975 Philip Warren Anderson, physics
1977 Albert Eschenmoser, chemistry
1979 Phillip Griffiths, mathematics
1981 Jacques Friedel, physics
1983 Gerd Faltings, mathematics
1986 Rudolf Thauer jr, biology
1987 Alex Müller and Georg Bednorz, physics
1989 Dieter Oesterhelt, biochemistry
1991 Jean-Pierre Demailly, mathematics
1993 Richard N. Zare, chemistry
1995 Donald M. Eigler, physics
1997 Regine Kahmann, biology
1999 Wolfgang Ketterle, physics
2001 Christopher C. Cummins, chemistry
2003 Michael Neuberger, biology
2005 Richard Taylor, mathematics
2007 Bertrand I. Halperin, physics
2009 Gerald F. Joyce, biology
2012 Krzysztof Matyjaszewski, chemistry
2013 Emmanuel Jean Candès, mathematics
2015 Andrea Cavalleri, physics
2018 , chemistry
2019 Oscar Randal-Williams, mathematics
2021 Viola Priesemann, physics
2024 Mayuko Yamashita, mathematical physics
See also
List of general science and technology awards
References
External links
Dannie Heineman Preis
Awards established in 1961
Science and technology awards | Dannie Heineman Prize (Göttingen) | [
"Technology"
] | 356 | [
"Science and technology awards"
] |
62,078,466 | https://en.wikipedia.org/wiki/Journal%20of%20Materials%20in%20Civil%20Engineering | The Journal of Materials in Civil Engineering is a monthly peer-reviewed scientific journal established in 1989 by the American Society of Civil Engineers. It covers research and best practices concerns on development, processing, evaluation, applications, and performance of construction materials in civil engineering. It consists of four sections: cementitious material, asphalt, geo-materials, and hybrids (which encompass steel, timber, masonry, and composite materials).
Abstracting and indexes
The journal is abstracted and indexed in Ei Compendex, ProQuest databases, Civil engineering database, Inspec, Scopus, and EBSCO databases.
References
External links
Civil engineering journals
American Society of Civil Engineers academic journals
Monthly journals
Materials science journals
English-language journals
Academic journals established in 1989 | Journal of Materials in Civil Engineering | [
"Materials_science",
"Engineering"
] | 154 | [
"Civil engineering journals",
"Civil engineering",
"Materials science journals",
"Materials science"
] |
62,078,710 | https://en.wikipedia.org/wiki/Realme%20X2%20Pro | The Realme X2 Pro is a smartphone from the Chinese smartphone manufacturer Realme, released in October 2019.
Specifications
The phone measures 161 mm × 75.7 mm × 8.7 mm (6.34 in × 2.98 in × 0.34 in) and weighs 192 grams (7.02 oz). It has an aluminum frame with Gorilla Glass 5 on the front and back. The display is a 6.5-inch Super AMOLED with 1080 by 2400 pixel resolution, 90 Hz refresh rate, and a maximum brightness of 1000 nits. The phone shipped with ColorOS 6.1, based on Android 9.0 ("Pie") but was upgraded to Realme UI 1.0 between March and April 2020. It contains a Qualcomm Snapdragon 855+ system on a chip, and an Adreno 640 GPU.
The phone has a rear-facing quad-camera array, with one 64 MP f/1.8 wide-angle lens (26 mm full-frame focal length equivalent), one 13 MP f/2.5 telephoto lens (52 mm equivalent), one 8 MP f/2.2 ultra-wide-angle lens (16 mm equivalent), and one 2 MP f/2.4 depth sensor. The three higher-resolution cameras are equipped with phase-detection autofocus. It also has a front-facing 16 MP f/2.0 wide-angle lens (25 mm equivalent).
The phone was sold in 3 variations: 6 GB RAM and 64 GB storage, 8 GB RAM and 128 GB storage and 12 GB RAM and 256 GB storage. The 6 GB/64 GB configuration was only available in the Indian market.
Reception
The phone received mostly positive reviews from critics. TechRadar gave it a score of 4.5/5, praising the phone's battery, speakers, and display with a 90 Hz refresh rate, while criticizing the software, image quality, and in-built gestures. The Verge described the phone as Realme's first phone with high-end specs. Android Authority gave it a review of 9.3/10, praising its display, internals, charging-speed, and camera setup, while criticizing the color OS and low-light camera performance. It also described the X2 Pro as having flagship specs.
Controversy
The smartphone's original operating system, ColorOS 6.1, allowed the unlocking of the phone's bootloader, allowing support for custom Android ROMs such as Lineage OS. When the phone upgraded to realme UI 1.0, in the first weeks any users with locked bootloader could no longer unlock, but soon Realme released an official method to unlock the bootloader.
References
"Realme X2 Pro: Price in Pakistan, Full Specifications & Features"
Realme mobile phones
Phablets
Mobile phones introduced in 2019
Chinese brands
Mobile phones with multiple rear cameras
Mobile phones with 4K video recording
Discontinued flagship smartphones | Realme X2 Pro | [
"Technology"
] | 617 | [
"Phablets",
"Crossover devices",
"Discontinued flagship smartphones",
"Flagship smartphones"
] |
62,079,633 | https://en.wikipedia.org/wiki/Kiyoshi%20Igusa | Kiyoshi Igusa (born November 28, 1949) is a Japanese-American mathematician and a professor at Brandeis University. He works in representation theory and topology.
Education and career
He studied at the University of Chicago and Princeton University, where he obtained his Ph.D. in 1979, under the direction of Allen Hatcher.
From 1981 to 1983, he was a Sloan Fellow, and since 2012 he is a Fellow of the American Mathematical Society.
In 1990, he gave an invited lecture at the ICM in Kyoto (Topology Section).
Personal life
Igusa's father, Jun-Ichi Igusa, was also a mathematician. Igusa is married to Gordana Todorov, with whom he is a frequent collaborator.
Selected publications
References
External links
(Personal Website)
Fellows of the American Mathematical Society
1949 births
Living people
Brandeis University faculty
American academics of Japanese descent
University of Chicago alumni
Princeton University alumni
21st-century American mathematicians
Sloan Research Fellows
20th-century American mathematicians
Topologists | Kiyoshi Igusa | [
"Mathematics"
] | 205 | [
"Topologists",
"Topology"
] |
73,056,460 | https://en.wikipedia.org/wiki/Candle%20Corporation | Candle Corporation was an American software company active from 1976 to 2004. The company spent the first two decades developing system monitoring applications for a variety of IBM mainframes and their corresponding software, their first being OMEGAMON which saw quick widespread adoption in commercial enterprises. In the mid-1990s, the company made pivots toward non-mainframe monitoring software and middleware. IBM acquired the company for between $350 million and $600 million in 2004.
History
1970s – 1980s
Aubrey G. Chernick (born 1949 in Los Angeles, California), the founder of Candle, grew up in Deloraine, Manitoba, after his family moved there from California. After graduating from the University of Manitoba with a Bachelor of Science in chemistry, he landed a job at the university's environmental protection laboratory, performing analyses of the Red River of the North. The minicomputers at the lab were Chernick's first hands-on experience with computers; with a fellow employee, he learned how to program in BASIC. Following this, Chernick deviated from his original career path of medicine to work as a software developer for Computer Science Corporation (CSC)'s Canadian subsidiary in Ontario. After getting laid off from CSC after three months, he worked as a programmer for Laurentian University, working on IBM's System/360 Model 40 mainframe, and for the Government of Manitoba, where he learned how to operate and code for IBM's MFT and MVS operating systems. These jobs provided Chernick his first experiences with mainframes.
While attending meetings hosted by in Ontario SHARE—a users' group for IBM mainframe personnel—Chernick observed recurring complaints from attendees, who spoke of not being able to satisfy common needs with IBM's operating systems. In 1975, Chernick convinced Canada Life's Ontario branch to let him use their mainframes as a development platform for an application that monitored system performance, in exchange for a bargain license for the final product. The finished software, which he named OMEGAMON/MVS, took roughly five months to develop. Immediately afterward, Chernick established Candle Services Corporation from his apartment in Toronto in October 1976 and began selling OMEGAMON door-to-door to various businesses (one such being Datacrown, where he unsuccessfully vied for employment). He named the company Candle both to convey enlightenment and warmth and to avoid the glut of tech-jargon-heavy names. In 1977, Chernick moved the company to West Los Angeles and abbreviated the company name to Candle Corporation. In California, he gained clients such as Southern California Edison, Northrop, Hughes Aircraft, TRW, and Warner Bros.
Candle employed 52 people in 1980 and logged $4.5 million in revenue for that year; in December alone the company recorded sales of $1 million. In January 1981, the company released OMEGAMON/CICS, a performance monitor oriented toward the financial sector and their transaction processing systems. In September 1982, Candle released MVS, targeting system administrators. Candle's sales in 1981 totaled $10.4 million, while employment grew to 108. That same year, the company established a philanthropic medical and health foundation, the Candle Foundation.
The company reached revenues of $100 million in 1988, a year after acquiring Chicago-based Netserv, Inc. By the end of the next year, Candle employed roughly 700 people. Candle was second in market share in the field of performance measurement software, according to Software Magazine, cornering 32 percent of the market. They were narrowly defeated by IBM (33 percent); third place was Boole & Babbage (13 percent). In 1988, the company released AF/OPERATOR, one of the first console automation software packages, and AF/REMOTE an automation management utility. Shortly after the company released OMEGAMON for DB/2 relational databases, which saw quick widespread adoption. In June 1989, the company announced OMEGACENTER, an integrated performance management and automation software package for data centers and large companies running local IBM mainframes. OMEGACENTER was one of the first performance measuring applications with a graphical user interface, via the Status Monitor tool.
1990s – 2000s
In summer 1990, Candle released OMEGAMON II, which integrated several of the company's existing applications and built on the graphical user interface of Status Monitor to these integrated functions. In 1991, the company unveiled three more software utilities, including a pair for DB/2 and the OMEGAVIEW status management utility. By the end of 1990, the company reached $151.4 million in sales. In 1991, they were named the 20th largest software company in Software Magazine. In late 1992, Candle moved its headquarters to a 150,000-square-foot building in the Water Garden area of Santa Monica, in the biggest office lease within Los Angeles County in 1992. It also opened a data center of its own, in the outskirts of Los Angeles. In 1993, Candle introduced OMEGACENTER for VMS and OMEGAMON II for SMS. Candle logged $210 million in sales that year; the following year, the company collected revenues of $213 million.
In 1995, the company released Candle Command Center (CCC), a suite of network and systems management software for servers running AIX and MVS and PC-compatible workstations running OS/2. With the release of CCC, Candle began pivoting away from mainframe software, the company simultaneously launching a $500 million research and development initiative to reinforce this pivot. The company also placed its first advertisement in a trade publication to communicate this move.
In 1996, Candle made yet another pivot toward developing middleware for networked computers. To this end, Candle acquired several companies: CleverSoft, Inc., a provider of management tools for servers running Lotus Notes based in Scarborough, Maine; AMSYS North America, a service provider for MQSeries based in Mendon, Massachusetts; PowerQ Software Corporation, a maker of MQSeries software development and testing environments; and Apertus Technologies' MQView for distributed MQSeries installations. Employment in Candle reached 1,200 in 1996, approximately 550 of which working in the company's 29 branch offices. During this time, the company's mainframe software and middleware were used in roughly 5,000 mainframes, and it counted 75 percent of the Fortune 500 among its clientele.
Candle relocated its headquarters again in 1999, moving about 700 employees from Santa Monica to a four-story 335,000-square-foot building in El Segundo—a building once occupied by Rockwell International for the Design and Engineering of B-1 Lancers. In the same year, the company shifted its focus to e-commerce and launched eBA*ServiceMonitor, a comprehensive monitoring application for online businesses. By the end of the millennium, Candle reached $382 million in revenue and employed 1,800 people total.
The company reached the 2,000 employee mark in 2000, the same year sales reached $400 million. In the next year, the company released OMEGAMON XE and DE, configurations of their flagship product centered on e-businesses, and a software-as-a-service platform, CandleNet eBusiness Platform, which facilitated the deployment of e-commerce services. The split between mainframe and non-mainframe pursuits within the company was 60-to-40 by this point. In 2002, the company released PathWAI, a line of software packages and consulting services for streamlining the process of designing and developing middleware and web server back-ends. Candle reached $207 million in revenue in 2002 and $328 million in sales in 2003.
IBM acquired Candle Corporation in April 2004 for an undisclosed sum. The deal was reportedly worth between $350 million and $600 million. After the acquisition, IBM absorbed Candle's assets into their Tivoli Software division.
References
IBM acquisitions
1976 establishments in Ontario
1977 disestablishments in Ontario
1977 establishments in California
2004 disestablishments in California
American companies established in 1976
American companies disestablished in 2004
Canadian companies established in 1976
Canadian companies disestablished in 1977
Defunct software companies of Canada
Defunct software companies of the United States
Software companies established in 1976
Software companies disestablished in 2004
Middleware | Candle Corporation | [
"Technology",
"Engineering"
] | 1,679 | [
"Software engineering",
"Middleware",
"IT infrastructure"
] |
73,059,571 | https://en.wikipedia.org/wiki/Hard%20Rock%20%28exercise%29 | Hard Rock (sometimes Operation Hard Rock or the Hard Rock exercise) was a British civil defence exercise planned by the Conservative government to take place in September–October 1982. One of a series of regular national civil defence exercises, it followed Square Leg in 1980. As the public reaction to the scale of devastation forecast in Square Leg was poor, the planners deliberately scaled down the number of warheads supposed for Hard Rock. Despite this, the Campaign for Nuclear Disarmament (CND), who opposed nuclear warfare and were against civil defence exercises, suggested that such an attack as Hard Rock anticipated would have led to the deaths of 12.5 million people.
Since 1980, many British local authorities, who played key roles in civil defence planning, had become nuclear-free zones, opposed to nuclear weapons and nuclear power. Many of these authorities refused to take part in Hard Rock, although finance and the unofficial policy of the Labour Party also played a part. By July, twenty local authorities, all Labour-run, had indicated their refusal to take part and seven more would take part in only a limited manner. Hard Rock was postponed indefinitely, effectively cancelled. In response, the government passed the Civil Defence (General Local Authority Functions) Regulations 1983, compelling local authorities to take part in civil defence exercises.
Planning
During the Cold War, the British government carried out a number of civil defence exercises to test the country's preparedness for the effects of war. Since 1949 this had included planning for an attack on the UK with nuclear weapons. From the mid-1970s national civil defence exercises, including a nuclear attack, had been run every 2–3 years. Hard Rock was scheduled to be run in September–October 1982 and would have been the largest civil defence exercise for 15 years. Planning for Hard Rock was started by the National Council for Civil Defence in 1980. It was the first British civil defence exercise to not be planned entirely by the military. The involvement of local authorities in the exercise came via the Civil Defence (Planning) Regulations 1974 which required them to maintain contingency plans for civil defence in their areas.
The attack scenario for the previous simulation, the 1980 Square Leg exercise, had been leaked to the press and the Campaign for Nuclear Disarmament (CND). This scenario envisaged more than 200 megatons of nuclear weapons being detonated on the country, a quantity in line with other British civil defence exercises conducted in the 1970s and advice in the Home Office's training manual for scientific advisors, issued in 1977. The public response to the projected high casualty rates and widespread destruction had been poor so the Hard Rock planners deliberately assumed an attack scenario with fewer weapons, totalling less than 50 megatons, and avoiding strikes on some obvious targets such as American air bases.
Journalist and writer on Cold War military secrets Duncan Campbell noted that no missiles were assumed to be targeted at London, Manchester, Edinburgh, Liverpool, Bristol or Cardiff and those targeted at other cities were presumed to miss; in addition, the US and British submarine bases at Holy Loch and Faslane and the main British and North Atlantic Treaty Organization (NATO) military control centres were also assumed not to be targets. Campbell lists 54 targets in the final exercise scenario, down from 105 in a June 1981 plan. He suggested that the Home Office and Ministry of Defence had removed "politically undesirable" targets from the scenario. He notes other political decisions affected the exercise: the scale of refugee movements was toned down and references to civil disorder were kept vague. The issuing of the Protect and Survive booklet to the public was to be one of the steps taken in the exercise but its brand had become so embarrassing to the government that it was referred to as the "Public, Do-It-Yourself Civil Defence" booklet.
Even with fewer nuclear weapons, the Hard Rock exercise projected large-scale damage and loss of life. The CND estimated that an attack of 50 megatons would result in the deaths of 12.5 million people, while an attack with 220 megatons would lead to the deaths of 39 million, some 72 per cent of the population at the time. The CND publicised these estimates under the title of "Hard Luck". Campbell, using a model by Philip Steadman of the Open University and Stan Openshaw of Newcastle University, forecast 12 million deaths or serious injuries, of which 2 million were forecast to come from the bombing and 5 million from the effects of fallout.
Exercise
According to Campbell, the exercise would have begun with a simulated transition to war period from 19 September, during which the officials in their bunkers would be given simulated daily briefings and news bulletins, including simulations of panic buying and fuel shortages. A war with the Soviet Union was to have broken out at 4:30am on 27 September with an invasion of West Germany and conventional air raids on the UK. During this time, the military had a limited role to play in the exercise, simulating reconnaissance flights over nuclear target areas and practising moving ships in and out of ports scheduled to remain unaffected. At 8:00pm on 2 October, the exercise forecast the nuclear strike would begin, continuing into the following morning. The exercise would run for a simulated one-month post-attack period.
Exercise Hard Rock would have focused on the response by local authorities in the aftermath of the attack. It envisaged the abandonment of irradiated cities, where fires would be left to burn uncontrolled, and the breakdown of society into lawlessness. The exercise included decisions made to triage casualties by likelihood of survival, with those affected by severe radiation sickness left to die without food or treatment, and the prioritisation of resources on those healthy adults with skills necessary to keep remaining infrastructure working. Campbell records that one of the measures taken in the exercise was the release of all bar 1,000 civilian prisoners.
Opposition and local authority refusals
The running of the Hard Rock exercise was opposed by the CND, who said it made no sense to run an exercise on post-attack response if the government's position was that the nuclear deterrent was effective. The pacifist Peace Pledge Union opposed the exercise on the grounds that it "normalised militarism".
In 1980, Manchester City Council declared itself a nuclear-free zone, proclaiming nuclear weapons and nuclear power unwelcome within its boundaries. It was the first British local authority to do so but by 1982, 143 authorities had joined it. Many of these authorities refused to participate in Hard Rock on principle, though other concerns such as cost were also a factor. Refusals were largely in local authorities controlled by the Labour Party, with some using it as an opportunity to demonstrate their opposition to the defence policies of the Conservative government. The Labour Party National Executive Committee (NEC) had, in June 1981, advised local authorities to "refuse to co-operate with all but the bare legal minimum necessary under the 1974 Civil Defence (Planning) exercises and arrangements which are concerned with nuclear weapons and nuclear war preparations".
The CND offered support to any authorities that decided not to participate and, with the Scientists Against Nuclear Arms organisation and the unofficial support of the Labour NEC, produced a pack of information outlining its views on the exercise. As part of its opposition to Hard Rock, the Greater London Council invited the public to view its secret nuclear bunkers, intended for post-attack command by civil defence personnel, with 4,800 people visiting them in six days. Had the exercise gone ahead protestors planned to establish peace camps outside the regional seats of government from which civil defence operations would be co-ordinated. The protestors planned to impede access to the facilities and to identify personnel who attended the exercises.
By July 1982, 19 county councils and the Greater London Council, out of the 54 local authorities which had been asked to participate, had confirmed their refusal. During Prime Minister's Questions on 15 July, the prime minister, Margaret Thatcher, stated that all 20 authorities that refused were Labour-run. A further seven local authorities stated that they could comply in only a limited manner. By September, the Home Secretary Willie Whitelaw had announced that the exercise had been indefinitely postponed, though it was, in effect, cancelled.
Legacy
Despite other factors such as politics and finance, the CND believed the cancellation of Hard Rock was primarily because of its campaign. The CND's Scottish secretary Ian Davison called it the organisation's first major victory and Peter Byrd, a writer on the history of the peace movement, described the cancellation as "probably [its] biggest single success". The government blamed the Labour NEC for the cancellation.
In the wake of the cancellation of Hard Rock, Michael Heseltine, secretary of state for defence, established Defence Secretariat 19 within the ministry to better explain to the public the government's policy on nuclear deterrence and multilateral disarmament. The government introduced the Civil Defence (General Local Authority Functions) Regulations in 1983. These compelled local authorities to support national civil defence exercises and imposed financial penalties for them and individual councillors if they did not comply. The regulations also gave the government the power to appoint special commissioners to run the exercises within the local authorities.
The civil service proposed running Hard Rock again after the Conservative victory in the 1983 general election but it was never run. That same year, Labour peer Willie Ross, Baron Ross of Marnock claimed, in the House of Lords, that the Ministry of Defence was glad the exercise had been cancelled as it would have showed widespread inadequacies in local civil defence planning. A Home Office investigation in 1988 found a widespread refusal by local authorities to implement the Civil Defence (General Local Authority Functions) Regulations 1983. From 1986 British civil defence planning transitioned away from large national exercises to the Planned Programme of Implementation (PPI) at a local level. PPI shifted the focus of civil defence preparations from nuclear war to an "all hazards" approach for a variety of civil emergencies.
Map of nuclear warhead targets
The following map indicates, according to Duncan Campbell, the targets for nuclear warheads supposed in Hard Rock. Air burst detonations are shown with blue markers, ground burst detonations with red markers. An asterisk (*) denotes a near miss which might be off target.
References
Nuclear warfare
United Kingdom nuclear command and control
Cold War history of the United Kingdom
1982 in the United Kingdom | Hard Rock (exercise) | [
"Chemistry"
] | 2,098 | [
"Radioactivity",
"Nuclear warfare"
] |
73,059,583 | https://en.wikipedia.org/wiki/CX%20Draconis | CX Draconis is an interacting binary star system in the northern constellation of Draco, abbreviated CX Dra. It has the designation HD 174237 in the Henry Draper Catalogue; CX Draconis is the variable star designation. This is a double-lined spectroscopic binary system with a near circular orbit. The brightness of the system undergoes long-term irregular fluctuations, ranging from an apparent visual magnitude of 5.68 down to 5.99. Based on parallax measurements, it is located at a distance of approximately 1,150 light years from the Sun.
In 1921, this target was found to have a varying radial velocity by J. S. Plaskett and associates. It was shown to be a Be star by O. C. Mohler in 1940, and in 1965 M. Lacoarret studied variations in the hydrogen alpha emission profiles from the target. This system was discovered to be a photometric variable by P. Merlin in 1975. P. Koubský measured the radial velocity variations in 1976, and in 1978 published orbital elements for this binary system with a period of 6.696 days. He found that the variation in emission lines matched the time scale of the orbit, indicating that this is an interacting binary.
Using observations from the Einstein Observatory, in 1984 this system was shown to be an X-ray source by E. F. Guinan and associates. This emission may be coming from the cooler secondary that is phase-locked with the primary and is magnetically active due to rapid rotation. In 1992, J. Horn and associates determined that the secondary component is an evolved F-type giant star. Evidence suggests this star is overflowing its Roche lobe with gas streaming toward the primary.
Models indicate that the main source of the H-alpha emission is located mid-way between the two stars, with other emission lines originating from an accretion disk orbiting the primary. The circumstellar environment is changing in cycles lasting hundreds of days. Infrared emission to the northeast of the system suggests it may be undergoing systematic mass loss.
References
Further reading
Be stars
F-type giants
Spectroscopic binaries
Gamma Cassiopeiae variable stars
Rotating ellipsoidal variables
Draco (constellation)
7084
Durchmusterung objects
174237
092133
Draconis, CX | CX Draconis | [
"Astronomy"
] | 475 | [
"Constellations",
"Draco (constellation)"
] |
73,060,426 | https://en.wikipedia.org/wiki/Hydroxyethyl%20acrylate | Hydroxyethyl acrylate is an organic chemical and an aliphatic compound. It has the formula C5H8O3 and the CAS Registry Number 818–61–1. It is REACH registered with an EU number of 212–454–9. It has dual functionality containing a polymerizable acrylic group and a terminal hydroxy group. It is used to make emulsion polymers along with other monomers and the resultant resins are used in coatings, sealants, adhesives and elastomers and other applications.
Synthesis
There are a number of patents and synthesis papers to produce the material mostly aimed at reducing or removing heavy metals as catalysts. The traditional manufacturing process calls for the reaction of ethylene oxide with acrylic acid in the presence of a metal catalyst.
Properties
The material is a clear water-white liquid with a mild but pungent ester like odor. It has a low freezing point.
Applications
The most common use for the material is to be copolymerized with other acrylate and methacrylate monomers to make emulsion and other polymers including hydrogels. Modification of rubbers and similar compounds is also a use for the material. The resultant polymers may be used to manufacture pressure-sensitive adhesives.
Toxicity
The toxicity of the material has been studied and is fairly well understood.
See also
(Hydroxyethyl)methacrylate
Synthetic resin
References
Monomers
Acrylate esters | Hydroxyethyl acrylate | [
"Chemistry",
"Materials_science"
] | 305 | [
"Monomers",
"Polymer chemistry"
] |
73,060,978 | https://en.wikipedia.org/wiki/TDI-11861 | TDI-11861 is a chemical compound which acts as a potent and selective inhibitor of soluble adenylyl cyclase (sAC). In animal studies it reversibly inhibits sperm motility, producing temporary infertility without hormonal side effects. While TDI-11861 is at an early developmental stage and is unlikely to be developed for medical uses in humans itself, it represents an important proof of concept which may potentially lead to the development of future male contraceptive drugs.
See also
CDD-2807
JQ1
YCT529
References
Chloroarenes
Pyrimidines
Morpholines
Pyrazoles
Difluoromethyl compounds | TDI-11861 | [
"Chemistry"
] | 144 | [
"Pharmacology",
"Pharmacology stubs",
"Medicinal chemistry stubs"
] |
73,061,251 | https://en.wikipedia.org/wiki/List%20of%20North%20American%20countries%20by%20life%20expectancy | This is a list of North American countries by life expectancy.
United Nations (2023)
Estimation of the analytical agency of the UN.
UN: Estimate of life expectancy for various ages in 2023
UN: Change of life expectancy from 2019 to 2023
World Bank Group (2022)
Estimation of the World Bank Group for 2022. The data is filtered according to the list of countries in North America. The values in the World Bank Group tables are rounded. All calculations are based on raw data; so due to the nuances of rounding, in some places illusory inconsistencies of indicators arose, with a size of 0.01 year.
In 2014, some of the world's leading countries had a local peak in life expectancy, so this year is chosen for comparison with 2019 and 2022.
WHO (2019)
Estimation of the World Health Organization for 2019.
Charts
See also
References
Life expectancy
North America | List of North American countries by life expectancy | [
"Biology"
] | 192 | [
"Senescence",
"Life expectancy"
] |
73,061,420 | https://en.wikipedia.org/wiki/Sofia%20lorry%20deaths | On 17 February 2023, an abandoned lorry carrying illegal immigrants believed to be from Afghanistan as well as timber was discovered near Lokorsko, a village 12 miles north-east of Sofia in Sofia City Province, Bulgaria.
Eighteen of the immigrants were dead and 34 others were taken to hospitals in Sofia. The deceased died due to a combination of lack of oxygen in an enclosed space and difficulty breathing due to the tight quarters. Bulgarian police arrested four people. Six people were charged with human trafficking charges shortly after the discovery, which included the truck driver and his companion.
See also
2022 San Antonio migrant deaths
Chiapas truck crash
Gualaca bus crash
List of migrant vehicle incidents in Europe
References
Sofia City Province
Migrant disasters in Europe
February 2023 events in Bulgaria
Afghanistan–Bulgaria relations
European migrant crisis
2023 disasters in Bulgaria
Deaths from hypoxia
2023 road incidents in Europe | Sofia lorry deaths | [
"Physics"
] | 178 | [
"Physical systems",
"Transport",
"Transport stubs"
] |
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