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63,017,060 | https://en.wikipedia.org/wiki/Arvind%20Krishna | Arvind Krishna (born November 23, 1962) is an Indian-American business executive, and the chairman and CEO of IBM. He has been CEO of IBM since April 2020 and chairman since January 2021. Krishna began his career at IBM in 1990, at its Thomas J. Watson Research Center, and was promoted to senior vice president in 2015, managing IBM Cloud & Cognitive Software and IBM Research divisions. He was a principal architect of the acquisition of Red Hat, the largest acquisition in the company’s history.
Early life and education
Krishna was born in a Telugu family in West Godavari District, in the Coastal Andhra region of Andhra Pradesh, India. His father, Major General Vinod Krishna, was an army officer who served in the Indian Army and his mother, Aarathi Krishna, worked for the welfare of Army widows. Krishna studied at Stanes Anglo Indian Higher Secondary School in Coonoor, Tamil Nadu, and at St Joseph's Academy, Dehradun.
Krishna received a Bachelor of Technology degree in electrical engineering from Indian Institute of Technology, Kanpur in 1985 and a Doctor of Philosophy in electrical engineering from the University of Illinois Urbana-Champaign in 1991.
Career
Professional career
Krishna joined IBM's Thomas J. Watson Research Center in 1990, and continued in Watson Research for 18 years until 2009. Thereafter, he held a General Manager role in Information management software and systems and technology group of IBM. In 2015, he was promoted to senior vice president of IBM Research. He later became senior vice president of IBM's cloud and cognitive software division.
Krishna also led the building and expansion of new markets for IBM in artificial intelligence, cloud, quantum computing, and blockchain technology. He was a driving force behind IBM's $34 billion acquisition of Red Hat, which closed in July 2019.
He was appointed IBM's CEO in January 2020, effective April 6, 2020, succeeding Ginni Rometty who was CEO since 2012. He joined Satya Nadella, Shantanu Narayen, and Sundar Pichai as an Indian-American CEO of a major United States technology company. In 2021, he was named by CRN as the year's "Most Influential Executive".
Research
He has co-authored 15 patents, has been the editor of IEEE and ACM journals, and has published extensively in technical journals.
Personal life
Krishna is married and has two children. He lives in Connecticut.
See also
Indians in the New York City metropolitan area
References
External links
Arvind Krishna – Forbes
1962 births
IBM employees
American computer businesspeople
21st-century American businesspeople
20th-century American businesspeople
American electrical engineers
American chief executives
American technology chief executives
American chief executives of Fortune 500 companies
IBM people
Living people
Telugu people
Engineers from Andhra Pradesh
Indian emigrants to the United States
IIT Kanpur alumni
Grainger College of Engineering alumni
Businesspeople from Andhra Pradesh
American people of Telugu descent
Chief executives in the technology industry | Arvind Krishna | [
"Technology"
] | 594 | [
"Lists of people in STEM fields",
"Proprietary technology salespersons"
] |
63,018,216 | https://en.wikipedia.org/wiki/Super%20Lemon%20Haze | Super Lemon Haze is a sativa-dominant cannabis strain (also referred to as a "cultivar") in the haze family of strains. It was originally bred by Franco Loja from the Netherlands-based Green House Seed Co. as a cross between two other strains: Lemon Skunk and Super Silver Haze.
Popular on the West Coast and British Columbia, Super Lemon Haze has been a two-time High Times Cannabis Cup winner from 2008 and 2009, Medical Cannabis Cup, and Spannabis Cup winner. Super Lemon Haze can be described as having a fresh lemon aroma, with an earthy, citrus flavor.
Characteristics
Super Lemon Haze traces its genetic lineage from two specific strains; Lemon Skunk and Super Silver Haze, which trace their lineage from Skunk #1 and a three-way cross of Skunk #1, Haze, and Northern Lights #5. Although the Super Lemon Haze strain predominantly features sativa genetics, their flowers come in all shapes and sizes, with a bright-green hue and a dense amount of trichomes. The pistils on this strain are a bright orange color when the plant is fully matured.
As cannabis is traditionally a photoperiod plant, Super Lemon Haze's grow period can last between 10 and 12 weeks. The yield is fairly high, with a range from anywhere between 600 and 800 grams per square meter per plant. According to Green House, this strain is best suited for growing in equatorial, tropical, subtropical and temperate climates, as its longer flowering period would present some difficulties in a colder environment.
In addition, Green House developed an autoflower version by hybridizing the plant's genetics with a ruderalis, which grows irrespective of the photoperiod.
Medicinal properties
Super Lemon Haze typically exhibits several terpenes, which are organic compounds that are produced by many plants, including cannabis. The most common dominant terpenes found in this strain are limonene, which is also found in citrus fruits such as lemons, and terpinolene. Terpenes present at lower levels may include beta-caryophyllene, ocimene, and myrcene, depending on the plant’s genotype.
The tetrahydrocannabinol (THC) content ranges from 15 to 20%, with some phenotypes testing as high as 25%. This strain also exhibits lower levels of other minor cannabinoids, with approximately 1-2% of cannabinol (CBN), which can be traced to its Super Silver Haze lineage, and less than 1% of CBD content. Green House has also developed a high-cannabidiol (CBD) version by breeding it with a high-CBD male plant. Current Super Lemon Haze genetics range up to levels of 25% THC, 2% CBN and 1% CBD making this strain ideal for treating certain conditions like pain and depression.
It is said that the mood-elevating properties of Super Lemon Haze can help regulate mood disorders, such as depression, while also helping with other conditions such as minor pains, nausea, and appetite loss. The effects can be described as uplifting, energetic, creative, and cerebral.
Awards
Super Lemon Haze has been recognized in the following cannabis competitions:
1st place High Times Cannabis Cup Amsterdam 2008
1st place High Times Cannabis Cup Amsterdam 2009
1st place IC420 Growers Cup Amsterdam 2010
2nd place High Times Cannabis Cup Amsterdam 2010
1st place High Times Medical Cup Seattle 2012
2nd place ExpoGrow Irun 2012
1st place ExpoGrow Irun 2013
1st place high times cannabis cup sativa Massachusetts 2021
References
External links
Cannabis strains
Cannabis in the Netherlands
| Super Lemon Haze | [
"Biology"
] | 744 | [
"Cannabis strains",
"Biopiracy"
] |
63,018,589 | https://en.wikipedia.org/wiki/Samsung%20Galaxy%20Watch%20Active%202 | The Samsung Galaxy Watch Active 2 (stylized as Samsung Galaxy Watch Active2) is a smartwatch developed by Samsung Electronics, running the Tizen operating system. Announced on 5 August 2019, the Active 2 was scheduled for availability in the United States starting on 23 September 2019.
The Active 2 was released in two sizes, 40mm or 44mm, and two connectivity formats, either Bluetooth or LTE capability. The LTE version functions as a standalone phone and allows a user to call, text, pay, and stream music or video without a nearby smartphone. An Under Armour Edition of the Active 2 was released on October 11, 2019, containing a watch face and strap branded with the Under Armour logo.
Samsung announced as part of the move to move from Tizen OS to Wear OS by Google starting from August 2022. The Watch Active 2 will stop receiving software and security updates while the Watch 3 will stop receiving software updates in 2023.
Specifications
References
External links
Galaxy Watch Active 2 on S
Consumer electronics brands
Products introduced in 2019
Smartwatches
Samsung wearable devices | Samsung Galaxy Watch Active 2 | [
"Technology"
] | 215 | [
"Smartwatches"
] |
63,018,939 | https://en.wikipedia.org/wiki/Quasicrystals%20and%20Geometry | Quasicrystals and Geometry is a book on quasicrystals and aperiodic tiling by Marjorie Senechal, published in 1995 by Cambridge University Press ().
One of the main themes of the book is to understand how the mathematical properties of aperiodic tilings such as the Penrose tiling, and in particular the existence of arbitrarily large patches of five-way rotational symmetry throughout these tilings, correspond to the properties of quasicrystals including the five-way symmetry of their Bragg peaks. Neither kind of symmetry is possible for a traditional periodic tiling or periodic crystal structure, and the interplay between these topics led from the 1960s into the 1990s to new developments and new fundamental definitions in both mathematics and crystallography.
Topics
The book is divided into two parts. The first part covers the history of crystallography, the use of X-ray diffraction to study crystal structures through the Bragg peaks formed on their diffraction patterns, and the discovery in the early 1980s of quasicrystals, materials that form Bragg peaks in patterns with five-way symmetry, impossible for a repeating crystal structure. It models the arrangement of atoms in a substance by a Delone set, a set of points in the plane or in Euclidean space that are neither too closely spaced nor too far apart, and it discusses the mathematical and computational issues in X-ray diffraction and the construction of the diffraction spectrum from a Delone set.
Finally, it discusses a method for constructing Delone sets that have Bragg peaks by projecting bounded subsets of higher-dimensional lattices into lower-dimensional spaces.
This material also has strong connections to spectral theory and ergodic theory, deep topics in pure mathematics, but these were omitted in order to make the book accessible to non-specialists in those topics.
Another method for the construction of Delone sets that have Bragg peaks is to choose as points the vertices of certain aperiodic tilings such as the Penrose tiling. (There also exist other aperiodic tilings, such as the pinwheel tiling, for which the existence of discrete peaks in the diffraction pattern is less clear.) The second part of the book discusses methods for generating these tilings, including projections of higher-dimensional lattices as well as recursive constructions with hierarchical structure, and it discusses the long-range patterns that can be shown to exist in tilings constructed in these ways.
Included in the book are software for generating diffraction patterns and Penrose tilings, and a "pictorial atlas" of the diffraction patterns of known aperiodic tilings.
Audience
Although the discovery of quasicrystals immediately set off a rush for applications in materials capable of withstanding high temperature, providing non-stick surfaces, or having other useful material properties, this book is more abstract and mathematical, and concerns mathematical models of quasicrystals rather than physical materials. Nevertheless, chemist István Hargittai writes that it can be read with interest by "students and researchers in mathematics, physics, materials science, and crystallography".
References
External links
Quasicrystals and Geometry on the Internet Archive
Aperiodic tilings
Mathematics books
1995 non-fiction books
Quasicrystals | Quasicrystals and Geometry | [
"Physics",
"Chemistry",
"Materials_science"
] | 663 | [
"Tessellation",
"Crystallography",
"Aperiodic tilings",
"Quasicrystals",
"Symmetry"
] |
63,019,363 | https://en.wikipedia.org/wiki/Ziresovir | Ziresovir (RO-0529, AK0529) is an antiviral drug which was developed as a treatment for respiratory syncytial virus. It acts as a fusion inhibitor, and has shown good results in Phase II and III clinical trials.
See also
Palivizumab
Presatovir
Lumicitabine
References
Anti–RNA virus drugs
Antiviral drugs
Sulfones
Oxetanes
Benzothiazepines
Quinazolines
Amines | Ziresovir | [
"Chemistry",
"Biology"
] | 99 | [
"Antiviral drugs",
"Functional groups",
"Sulfones",
"Amines",
"Biocides",
"Bases (chemistry)"
] |
63,019,482 | https://en.wikipedia.org/wiki/Absorption%20rate%20constant | The absorption rate constant Ka is a value used in pharmacokinetics to describe the rate at which a drug enters into the system. It is expressed in units of time−1. The Ka is related to the absorption half-life (t1/2a) per the following equation: Ka = ln(2) / t1/2a.
Ka values can typically only be found in research articles. This is in contrast to parameters like bioavailability and elimination half-life, which can often be found in drug and pharmacology handbooks.
References
Pharmacokinetic metrics | Absorption rate constant | [
"Chemistry"
] | 125 | [
"Pharmacology",
"Pharmacology stubs",
"Medicinal chemistry stubs"
] |
63,019,487 | https://en.wikipedia.org/wiki/Xenon%20tetrachloride | Xenon tetrachloride is an unstable inorganic compound with the chemical formula XeCl4. Unlike other noble gas/halide compounds, it cannot be synthesized by simply combining the elements, by using a more-active halogenating agent, or by substitution of other halides on tetrahaloxenon compounds. Instead, a decay technique can be used, starting with K129ICl4. The iodine-129 atom of the covalent cluster is radioactive and undergoes beta decay to become xenon-129. The resulting XeCl4 molecule has a square planar molecular geometry analogous to xenon tetrafluoride.
Alternately, the product can be obtained by subjecting the elements to an electric discharge.
References
Xenon(IV) compounds
Chlorides | Xenon tetrachloride | [
"Chemistry"
] | 165 | [
"Chlorides",
"Inorganic compounds",
"Salts"
] |
63,019,703 | https://en.wikipedia.org/wiki/Star%20Party%20Sri%20Lanka | Star Party Sri Lanka, commonly known as Star Party, is an astronomical observation competition held in Sri Lanka since 2004, jointly organised by Ananda College, Colombo and Mahamaya Girls' College, Kandy. It is the longest-running inter-school astronomical observation competition in Sri Lanka. It happens annually at the University of Peradeniya premises typically in the first quarter of the year. However, in some years it was held in the other periods of the year due to various reasons. Star Party is considered the most important event in the Sri Lankan amateur astronomical calendar.
Observation competition
Star Party night sky observation competition is the main focus event of the entire Star Party. High school students from all around the country teamed up and compete for the title "Best school-based astronomical observation team of the year" and the Star Party challenge trophy. A team consists of 5 members from the same school and there can be a maximum of two teams (namely A and B) that can compete from one school. The competition held under 6 sections as follows,
Best in Moon observation.
Best in planetary observation.
Best in deep-sky observation and constellation mapping.
Best in observational astronomy (Theory).
Best in celestial measurements.
The highest-scoring team of each of those sections wins the sub-trophy for the respective titles. The team that has the highest total score for all these sections wins the Star Party Challenge trophy and crowned as the Champions of the Star Party.
References
Astronomy education events
Annual events in Sri Lanka | Star Party Sri Lanka | [
"Astronomy"
] | 302 | [
"Astronomy education",
"Astronomy education events",
"Astronomy events"
] |
63,024,728 | https://en.wikipedia.org/wiki/Puer%20mingens | A puer mingēns (; : puerī mingentēs ) is a figure in a work of art depicted as a prepubescent boy in the act of urinating, either actual or simulated. The puer mingens could represent anything from whimsy and boyish innocence to erotic symbols of virility and masculine bravado.
Etymology and word play
The term puer mingens comes from the Latin puer, meaning "boy", and from the Latin mingens; "urinating", the present participle of the verb mingere which means "to urinate".
In Latin, verbs for urinating like mingere were frequently employed in the sense of "to ejaculate". This connotation was preserved in various descendants of Latin, including Italian with such words as pisciare. On account of this, the urine emitted from the penis of the puer mingens can be interpreted symbolically as semen; and pueri mingentes are frequently found in works auguring fertility and fecundity. Lorenzo Lotto's Venus and Cupid is an example.
In several languages, such as Italian, French, and English, "to make water" was a euphemism for urinating. In allusion to this, one can find depictions of a puer mingens "making water" in works such as Michelangelo's Children's Bacchanal, or in church lavabos whose waterspouts are positioned in front of naked boys' groins (thereby giving the illusion that their urine has been transformed into water). Pueri mingentes were frequently incorporated as fully functioning statues whose pipes shot forth streams of water out of the statues' penises. One of the most famous examples of this is the Manneken Pis in Brussels.
Renaissance revivals of puer mingens
Pueri mingentes are a classical motif occasionally found in antiquity. Ancient Roman examples of pueri mingentes occurred mainly on children's sarcophagi.
The puer mingens was revived during the Renaissance. Donatello, who paved the way in the reinvention of the larger motif of the putti in sculpture, depicted one of the earliest Renaissance examples of a puer mingens on the base of his Judith and Holofernes statue. From its revival in 15th-century Florence, the artistic motif of urinating boys spread throughout the rest of Europe, reaching its height of popularity during the late Renaissance in the sixteenth and seventeenth centuries before gradually receding in popularity.
Pueri mingentes locations
In Roman times the puer mingens was generally found in depictions of Bacchic rites on children's sarcophagi. From the Renaissance onward, the puer mingens can be found in both secular and religious art and across a range of media, from illuminated manuscripts, functional fountains, frescoes, to apotropaic amulets.
Owing to the abovementioned associations with fertility, pueri mingentes are found on deschi da parto – trays given to pregnant women and those who had recently given birth in order to betoken and celebrate the healthy birth of male offspring. Paintings intended as wedding gifts, such as Lorenzo Lotto's Venus and Cupid, might also feature urinating boys.
The puer mingens was prominently incorporated into fountains that would shoot water out of the statue's penis. Although this artistic motif is Roman in origin, there is scant attestation of working fountains incorporating pueri mingentes in Roman times; the Romans did, however, have functional statues portraying the adult Priapus urinating, which may have inspired the Renaissance development of statues of urinating boys. In addition to public spaces, such as the Manneken Pis's location in central Brussels, functional fountains also graced many private sixteenth- and seventeenth-century gardens across Europe.
Gallery
See also
Putti – Artistic depictions of naked boys
Manneken Pis (1619) – A bronze statue in Brussels of a naked little boy urinating
Tea pet
References
External links
Latin words and phrases
Renaissance art
Visual motifs
Iconography
Phallic monuments
Ornaments | Puer mingens | [
"Mathematics"
] | 840 | [
"Symbols",
"Visual motifs"
] |
63,025,216 | https://en.wikipedia.org/wiki/Lumicitabine | Lumicitabine (ALS-8176) is an antiviral drug which was developed as a treatment for respiratory syncytial virus (RSV) and human metapneumovirus (hMPV). It acts as an RNA polymerase inhibitor. While it showed promise in early clinical trials, poor results in Phase IIb trials led to it being discontinued from development for treatment of RSV. Research continues to determine whether it may be useful for the treatment of diseases caused by other RNA viruses, and it has been found to show activity against Nipah virus.
See also
Palivizumab
Presatovir
Ziresovir
References
Anti–RNA virus drugs
Antiviral drugs
Tetrahydrofurans
Pyrimidines
Abandoned drugs | Lumicitabine | [
"Chemistry",
"Biology"
] | 159 | [
"Antiviral drugs",
"Biocides",
"Drug safety",
"Abandoned drugs"
] |
63,026,134 | https://en.wikipedia.org/wiki/Naiomi%20Cameron | Naiomi Tuere Cameron is an American mathematician working in the field of combinatorics. She is an associate professor at Spelman College as well as the vice president of National Association of Mathematicians. She was previously an associate professor at Lewis & Clark College in Portland, OR.
Cameron was born in Washington, D.C. and raised in Providence, Rhode Island. She attended Howard University for her undergraduate and graduate school, receiving both her B.S. and PhD in Mathematics. In 2019, she was featured on Mathematically Gifted and Black as a Black History Month 2019 Honoree.
Research
Cameron's academic work has been focused on enumerative and algebraic combinatorics and number theory. Her thesis for her dissertation in 2002 was Random Walks, Trees and Extensions of Riordan Group Techniques. Her other publications include:
Additional work
Cameron is the vice president of the National Association of Mathematicians for the 2019–2020 term.
References
External links
21st-century American mathematicians
21st-century American women mathematicians
Combinatorialists
Howard University alumni
Spelman College faculty
Living people
Year of birth missing (living people) | Naiomi Cameron | [
"Mathematics"
] | 222 | [
"Combinatorialists",
"Combinatorics"
] |
63,027,196 | https://en.wikipedia.org/wiki/Binakael | Binakael (binakel, binakol, binakul) (transliterated, "to do a sphere") is a type of weaving pattern traditional in the Philippines. Patterns consisting entirely of straight lines are woven so as to create the illusion of curves and volumes. A sense of motion is also sought. Designs are geometric, but often representational. The techniques create illusionistic designs similar to op art patterns and were popular by the late 19th century, when the United States colonized the Philippines and American museums collected many traditional Philippine textiles.
thumb|right|175px| Ilocos Sur weaver
Binakael patterns may use a two-block rep weave, making them double-sided, but with colour reversal.
In culture
Mara Coson's novel "Aliasing" was inspired by binakael weave.
Cebu Pacific introduced its QR Flight codes pattered after traditional weaving of nature-inspired design of Ilocos Norte's Binakol to promote local tourism.
See also
Op art
Inabel
T'nalak
References
Weaving
Optical illusions
Philippine handicrafts | Binakael | [
"Physics"
] | 222 | [
"Optical phenomena",
"Physical phenomena",
"Optical illusions"
] |
63,027,314 | https://en.wikipedia.org/wiki/%C3%84kta%20Explorer | The ÄKTA explorer was the first high end FPLC (Fast Protein Liquid Chromatography) system that was developed for Life Science research by the Swedish company Pharmacia in 1994. Its purpose was to simplify and automatize protein purification. It was followed by a line of similar devices (the "Äkta" line). The product line name was transferred together with the sale of Pharmacia first to Amersham and then to GE Healthcare. Although protein purification is possible with a large range of chromatographic devices, the Äkta line represents together with BioRad's NGC line the only devices that were specifically designed for this purpose both from the hardware and software perspective. Main users of these devices are the pharmaceutical industry and academic researchers.
References
Chromatography | Äkta Explorer | [
"Chemistry"
] | 164 | [
"Chromatography",
"Separation processes"
] |
63,028,251 | https://en.wikipedia.org/wiki/Chinese%20Society%20for%20Rock%20Mechanics%20%26%20Engineering | The Chinese Society for Rock Mechanics & Engineering (; abbreviated CSRME) is a professional body and learned society in the field of rock mechanics in China with a focus on water conservation and hydropower, geology and mining, railway transport, national defense engineering, disaster control, environmental protection. As of 2018, it has 6 subordinate working committees, 13 specialized committees, 12 branches, 19 local societies, and 12,674 individual members. It is a constituent of the China Association for Science and Technology (CAST) and a member of the International Society for Rock Mechanics (ISRM).
History
The Chinese Society for Rock Mechanics & Engineering started in 1978 as NG China in the International Society for Rock Mechanics (ISRM). The preparatory committee was founded in 1981 and it was officially established in June 1985.
Scientific publishing
Chinese Journal of Rock Mechanics and Engineering
List of presidents
References
External links
Geotechnical organizations
Rock mechanics
Scientific organizations established in 1985
Organizations based in Beijing
1985 establishments in China
1985 in Beijing | Chinese Society for Rock Mechanics & Engineering | [
"Engineering"
] | 199 | [
"Geotechnical organizations",
"Civil engineering organizations"
] |
63,028,441 | https://en.wikipedia.org/wiki/Embryo%20Ranking%20Intelligent%20Classification%20Algorithm | Embryo Ranking Intelligent Classification Algorithm (ERICA) is a deep learning AI software designed to assist embryologists and clinicians during the embryo selection process leading to embryo transfer, a critical step of in vitro fertilisation treatments (IVF).
This AI-based software relies on artificial vision to extract features not identifiable with the use of conventional microscopy. Following feature extraction, ERICA accurately ranks embryos according to their prognosis (defined as euploidy and implantation potential). In this way, ERICA removes the subjectivity inherent to previously existing classifications and, by efficiently assisting clinicians, increases the chances of selecting the one embryo with the best chances to become a baby.
ERICA's algorithms and the EmbryoRanking.com associated software are cloud-based and base their ranking system on predicting individual embryo's genetic status in a non-invasive fashion.
See also
Embryo selection
In vitro fertilisation and embryo selection
References
Applications of artificial intelligence
Assisted reproductive technology | Embryo Ranking Intelligent Classification Algorithm | [
"Biology"
] | 196 | [
"Assisted reproductive technology",
"Medical technology"
] |
63,029,619 | https://en.wikipedia.org/wiki/Pokhozhaev%27s%20identity | Pokhozhaev's identity is an integral relation satisfied by stationary localized solutions to a nonlinear Schrödinger equation or nonlinear Klein–Gordon equation. It was obtained by S.I. Pokhozhaev and is similar to the virial theorem. This relation is also known as G.H. Derrick's theorem. Similar identities can be derived for other equations of mathematical physics.
The Pokhozhaev identity for the stationary nonlinear Schrödinger equation
Here is a general form due to H. Berestycki and P.-L. Lions.
Let be continuous and real-valued, with .
Denote .
Let
be a solution to the equation
,
in the sense of distributions.
Then satisfies the relation
The Pokhozhaev identity for the stationary nonlinear Dirac equation
There is a form of the virial identity for the stationary nonlinear Dirac equation in three spatial dimensions (and also the Maxwell-Dirac equations) and in arbitrary spatial dimension.
Let
and let and be the self-adjoint Dirac matrices of size :
Let be the massless Dirac operator.
Let be continuous and real-valued, with .
Denote .
Let be a spinor-valued solution that satisfies the stationary form of the nonlinear Dirac equation,
in the sense of distributions,
with some .
Assume that
Then satisfies the relation
See also
Virial theorem
Derrick's theorem
References
Mathematical_identities
Theorems in mathematical physics
Physics theorems | Pokhozhaev's identity | [
"Physics",
"Mathematics"
] | 300 | [
"Mathematical theorems",
"Equations of physics",
"Theorems in mathematical physics",
"Mathematical identities",
"Mathematical problems",
"Algebra",
"Physics theorems"
] |
63,029,820 | https://en.wikipedia.org/wiki/Photoactivated%20adenylyl%20cyclase | Photoactivated adenylyl cyclase (PAC) is a protein consisting of an adenylyl cyclase enzyme domain directly linked to a BLUF (blue light receptor using FAD) type light sensor domain. When illuminated with blue light, the enzyme domain becomes active and converts ATP to cAMP, an important second messenger in many cells. In the unicellular flagellate Euglena gracilis, PACα and PACβ (euPACs) serve as a photoreceptor complex that senses light for photophobic responses and phototaxis. Small but potent PACs were identified in the genome of the bacteria Beggiatoa (bPAC) and Oscillatoria acuminata (OaPAC). While natural bPAC has some enzymatic activity in the absence of light, variants with no dark activity have been engineered (PACmn).
Use of PACs as optogenetic tools
As PACs consist of a light sensor and an enzyme in a single protein, they can be expressed in other species and cell types to manipulate cAMP levels with light. When bPAC is expressed in mouse sperm, blue light illumination speeds up the swimming of transgenic sperm cells and aids fertilization. When expressed in neurons, illumination changes the branching pattern of growing axons. PAC has been used in mice to clarify the function of neurons in the hypothalamus, which use cAMP signaling to control mating behavior. Expression of PAC together with K+-specific cyclic-nucleotide-gated ion channels (CNGs) has been used to hyperpolarize neurons at very low light levels, which prevents them from firing action potentials.
Rhodopsin guanylyl cyclases
Photoactivated guanylyl cyclases have been discovered in the aquatic fungi Blastocladiella emersonii and Catenaria anguillulae. Unlike PACs, these light-activated cyclases use retinal as their light sensor and are therefore rhodopsin guanylyl cyclases (RhGC). When expressed in Xenopus oocytes or mammalian neurons, RhGCs generate cGMP in response to green light. Therefore, they are considered useful optogenetic tools to investigate cGMP signaling.
References
Protein families
EC 4.6.1
Cell biology
Neurochemistry | Photoactivated adenylyl cyclase | [
"Chemistry",
"Biology"
] | 494 | [
"Cell biology",
"Protein classification",
"Biochemistry",
"Protein families",
"Neurochemistry"
] |
63,030,231 | https://en.wikipedia.org/wiki/COVID-19 | Coronavirus disease 2019 (COVID-19) is a contagious disease caused by the coronavirus SARS-CoV-2. In January 2020 the disease spread worldwide, resulting in the COVID-19 pandemic.
The symptoms of COVID‑19 can vary but often include fever, fatigue, cough, breathing difficulties, loss of smell, and loss of taste. Symptoms may begin one to fourteen days after exposure to the virus. At least a third of people who are infected do not develop noticeable symptoms. Of those who develop symptoms noticeable enough to be classified as patients, most (81%) develop mild to moderate symptoms (up to mild pneumonia), while 14% develop severe symptoms (dyspnea, hypoxia, or more than 50% lung involvement on imaging), and 5% develop critical symptoms (respiratory failure, shock, or multiorgan dysfunction). Older people have a higher risk of developing severe symptoms. Some complications result in death. Some people continue to experience a range of effects (long COVID) for months or years after infection, and damage to organs has been observed. Multi-year studies on the long-term effects are ongoing.
COVID‑19 transmission occurs when infectious particles are breathed in or come into contact with the eyes, nose, or mouth. The risk is highest when people are in close proximity, but small airborne particles containing the virus can remain suspended in the air and travel over longer distances, particularly indoors. Transmission can also occur when people touch their eyes, nose or mouth after touching surfaces or objects that have been contaminated by the virus. People remain contagious for up to 20 days and can spread the virus even if they do not develop symptoms.
Testing methods for COVID-19 to detect the virus's nucleic acid include real-time reverse transcription polymerase chain reaction (RTPCR), transcription-mediated amplification, and reverse transcription loop-mediated isothermal amplification (RTLAMP) from a nasopharyngeal swab.
Several COVID-19 vaccines have been approved and distributed in various countries, many of which have initiated mass vaccination campaigns. Other preventive measures include physical or social distancing, quarantining, ventilation of indoor spaces, use of face masks or coverings in public, covering coughs and sneezes, hand washing, and keeping unwashed hands away from the face. While drugs have been developed to inhibit the virus, the primary treatment is still symptomatic, managing the disease through supportive care, isolation, and experimental measures.
The first known case was identified in Wuhan, China, in December 2019. Most scientists believe the SARS-CoV-2 virus entered into human populations through natural zoonosis, similar to the SARS-CoV-1 and MERS-CoV outbreaks, and consistent with other pandemics in human history. Social and environmental factors including climate change, natural ecosystem destruction and wildlife trade increased the likelihood of such zoonotic spillover.
Nomenclature
During the initial outbreak in Wuhan, the virus and disease were commonly referred to as "coronavirus" and "Wuhan coronavirus", with the disease sometimes called "Wuhan pneumonia". In the past, many diseases have been named after geographical locations, such as the Spanish flu, Middle East respiratory syndrome, and Zika virus. In January 2020, the World Health Organization (WHO) recommended 2019-nCoV and 2019-nCoV acute respiratory disease as interim names for the virus and disease per 2015 guidance and international guidelines against using geographical locations or groups of people in disease and virus names to prevent social stigma. The official names COVID‑19 and SARS-CoV-2 were issued by the WHO on 11 February 2020 with COVID-19 being shorthand for "coronavirus disease 2019". The WHO additionally uses "the COVID‑19 virus" and "the virus responsible for COVID‑19" in public communications.
Symptoms and signs
Complications
Complications may include pneumonia, acute respiratory distress syndrome (ARDS), multi-organ failure, septic shock, and death. Cardiovascular complications may include heart failure, arrhythmias (including atrial fibrillation), heart inflammation, thrombosis, particularly venous thromboembolism, and endothelial cell injury and dysfunction. Approximately 20–30% of people who present with COVID‑19 have elevated liver enzymes, reflecting liver injury.
Neurologic manifestations include seizure, stroke, encephalitis, and Guillain–Barré syndrome (which includes loss of motor functions). Following the infection, children may develop paediatric multisystem inflammatory syndrome, which has symptoms similar to Kawasaki disease, which can be fatal. In very rare cases, acute encephalopathy can occur, and it can be considered in those who have been diagnosed with COVID‑19 and have an altered mental status.
According to the US Centers for Disease Control and Prevention, pregnant women are at increased risk of becoming seriously ill from COVID‑19. This is because pregnant women with COVID‑19 appear to be more likely to develop respiratory and obstetric complications that can lead to miscarriage, premature delivery and intrauterine growth restriction.
Fungal infections such as aspergillosis, candidiasis, cryptococcosis and mucormycosis have been recorded in people recovering from COVID‑19.
Cause
COVID‑19 is caused by infection with a strain of coronavirus known as "severe acute respiratory syndrome coronavirus 2" (SARS-CoV-2).
Transmission
Virology
Severe acute respiratory syndrome coronavirus2 (SARS-CoV-2) is a novel severe acute respiratory syndrome coronavirus. It was first isolated from three people with pneumonia connected to the cluster of acute respiratory illness cases in Wuhan. All structural features of the novel SARS-CoV-2 virus particle occur in related coronaviruses in nature, particularly in Rhinolophus sinicus (Chinese horseshoe bats).
Outside the human body, the virus is destroyed by household soap which bursts its protective bubble. Hospital disinfectants, alcohols, heat, povidone-iodine, and ultraviolet-C (UV-C) irradiation are also effective disinfection methods for surfaces.
SARS-CoV-2 is closely related to the original SARS-CoV. It is thought to have an animal (zoonotic) origin. Genetic analysis has revealed that the coronavirus genetically clusters with the genus Betacoronavirus, in subgenus Sarbecovirus (lineage B) together with two bat-derived strains. It is 96% identical at the whole genome level to other bat coronavirus samples (BatCov RaTG13). The structural proteins of SARS-CoV-2 include membrane glycoprotein (M), envelope protein (E), nucleocapsid protein (N), and the spike protein (S). The M protein of SARS-CoV-2 is about 98% similar to the M protein of bat SARS-CoV, maintains around 98% homology with pangolin SARS-CoV, and has 90% homology with the M protein of SARS-CoV; whereas, the similarity is only around 38% with the M protein of MERS-CoV.
SARS-CoV-2 variants
The many thousands of SARS-CoV-2 variants are grouped into either clades or lineages. The WHO, in collaboration with partners, expert networks, national authorities, institutions and researchers, have established nomenclature systems for naming and tracking SARS-CoV-2 genetic lineages by GISAID, Nextstrain and Pango. The expert group convened by the WHO recommended the labelling of variants using letters of the Greek alphabet, for example, Alpha, Beta, Delta, and Gamma, giving the justification that they "will be easier and more practical to discussed by non-scientific audiences". Nextstrain divides the variants into five clades (19A, 19B, 20A, 20B, and 20C), while GISAID divides them into seven (L, O, V, S, G, GH, and GR). The Pango tool groups variants into lineages, with many circulating lineages being classed under the B.1 lineage.
Several notable variants of SARS-CoV-2 emerged throughout 2020. Cluster 5 emerged among minks and mink farmers in Denmark. After strict quarantines and the slaughter of all the country's mink, the cluster was assessed to no longer be circulating among humans in Denmark as of 1 February 2021.
, there are five dominant variants of SARS-CoV-2 spreading among global populations: the Alpha variant (B.1.1.7, formerly called the UK variant), first found in London and Kent, the Beta variant (B.1.351, formerly called the South Africa variant), the Gamma variant (P.1, formerly called the Brazil variant), the Delta variant (B.1.617.2, formerly called the India variant), and the Omicron variant (B.1.1.529), which had spread to 57 countries as of 7 December.
On December 19, 2023, the WHO declared that another distinctive variant, JN.1, had emerged as a "variant of interest". Though the WHO expected an increase in cases globally, particularly for countries entering winter, the overall global health risk was considered low.
Pathophysiology
The SARS-CoV-2 virus can infect a wide range of cells and systems of the body. COVID‑19 is most known for affecting the upper respiratory tract (sinuses, nose, and throat) and the lower respiratory tract (windpipe and lungs). The lungs are the organs most affected by COVID‑19 because the virus accesses host cells via the receptor for the enzyme angiotensin-converting enzyme 2 (ACE2), which is most abundant on the surface of type II alveolar cells of the lungs. The virus uses a special surface glycoprotein called a "spike" to connect to the ACE2 receptor and enter the host cell.
Respiratory tract
Following viral entry, COVID‑19 infects the ciliated epithelium of the nasopharynx and upper airways. Autopsies of people who died of COVID‑19 have found diffuse alveolar damage, and lymphocyte-containing inflammatory infiltrates within the lung.
From the CT scans of COVID-19 infected lungs, white patches were observed containing fluid known as ground-glass opacity (GGO) or simply ground glass. This tended to correlate with the clear jelly liquid found in lung autopsies of people who died of COVID-19. One possibility addressed in medical research is that hyuralonic acid (HA) could be the leading factor for this observation of the clear jelly liquid found in the lungs, in what could be hyuralonic storm, in conjunction with cytokine storm.
Nervous system
One common symptom, loss of smell, results from infection of the support cells of the olfactory epithelium, with subsequent damage to the olfactory neurons. The involvement of both the central and peripheral nervous system in COVID‑19 has been reported in many medical publications. It is clear that many people with COVID-19 exhibit neurological or mental health issues. The virus is not detected in the central nervous system (CNS) of the majority of people with COVID-19 who also have neurological issues. However, SARS-CoV-2 has been detected at low levels in the brains of those who have died from COVID‑19, but these results need to be confirmed. While virus has been detected in cerebrospinal fluid of autopsies, the exact mechanism by which it invades the CNS remains unclear and may first involve invasion of peripheral nerves given the low levels of ACE2 in the brain. The virus may also enter the bloodstream from the lungs and cross the blood–brain barrier to gain access to the CNS, possibly within an infected white blood cell.
Research conducted when Alpha was the dominant variant has suggested COVID-19 may cause brain damage. Later research showed that all variants studied (including Omicron) killed brain cells, but the exact cells killed varied by variant. It is unknown if such damage is temporary or permanent. Observed individuals infected with COVID-19 (most with mild cases) experienced an additional 0.2% to 2% of brain tissue lost in regions of the brain connected to the sense of smell compared with uninfected individuals, and the overall effect on the brain was equivalent on average to at least one extra year of normal ageing; infected individuals also scored lower on several cognitive tests. All effects were more pronounced among older ages.
Gastrointestinal tract
The virus also affects gastrointestinal organs as ACE2 is abundantly expressed in the glandular cells of gastric, duodenal and rectal epithelium as well as endothelial cells and enterocytes of the small intestine.
Cardiovascular system
The virus can cause acute myocardial injury and chronic damage to the cardiovascular system. An acute cardiac injury was found in 12% of infected people admitted to the hospital in Wuhan, China, and is more frequent in severe disease. Rates of cardiovascular symptoms are high, owing to the systemic inflammatory response and immune system disorders during disease progression, but acute myocardial injuries may also be related to ACE2 receptors in the heart. ACE2 receptors are highly expressed in the heart and are involved in heart function.
A high incidence of thrombosis and venous thromboembolism occurs in people transferred to intensive care units with COVID‑19 infections, and may be related to poor prognosis. Blood vessel dysfunction and clot formation (as suggested by high D-dimer levels caused by blood clots) may have a significant role in mortality, incidents of clots leading to pulmonary embolisms, and ischaemic events (strokes) within the brain found as complications leading to death in people infected with COVID‑19. Infection may initiate a chain of vasoconstrictive responses within the body, including pulmonary vasoconstriction a possible mechanism in which oxygenation decreases during pneumonia. Furthermore, damage of arterioles and capillaries was found in brain tissue samples of people who died from COVID‑19.
COVID19 may also cause substantial structural changes to blood cells, sometimes persisting for months after hospital discharge. A low level of blood lymphocytess may result from the virus acting through ACE2-related entry into lymphocytes.
Kidneys
Another common cause of death is complications related to the kidneys. Early reports show that up to 30% of people hospitalised with COVID-19 both in China and in New York have experienced some injury to their kidneys, including some persons with no previous kidney problems.
Immunopathology
Although SARS-CoV-2 has a tropism for ACE2-expressing epithelial cells of the respiratory tract, people with severe COVID‑19 have symptoms of systemic hyperinflammation. Clinical laboratory findings of elevated IL2, IL6, IL7, as well as the following suggest an underlying immunopathology:
Granulocyte-macrophage colony-stimulating factor (GMCSF)
Interferon gamma-induced protein10 (IP10)
Monocyte chemoattractant protein1 (MCP1)
Macrophage inflammatory protein 1alpha (MIP1alpha)
Tumour necrosis factor (TNFα) indicative of cytokine release syndrome (CRS)
Interferon alpha plays a complex, Janus-faced role in the pathogenesis of COVID-19. Although it promotes the elimination of virus-infected cells, it also upregulates the expression of ACE-2, thereby facilitating the SARS-Cov2 virus to enter cells and to replicate. A competition of negative feedback loops (via protective effects of interferon alpha) and positive feedback loops (via upregulation of ACE-2) is assumed to determine the fate of people with COVID-19.
Additionally, people with COVID‑19 and acute respiratory distress syndrome (ARDS) have classical serum biomarkers of CRS, including elevated C-reactive protein (CRP), lactate dehydrogenase (LDH), D-dimer, and ferritin.
Systemic inflammation results in vasodilation, allowing inflammatory lymphocytic and monocytic infiltration of the lung and the heart. In particular, pathogenic GM-CSF-secreting T cells were shown to correlate with the recruitment of inflammatory IL-6-secreting monocytes and severe lung pathology in people with COVID‑19. Lymphocytic infiltrates have also been reported at autopsy.
Viral and host factors
Virus proteins
Multiple viral and host factors affect the pathogenesis of the virus. The S-protein, otherwise known as the spike protein, is the viral component that attaches to the host receptor via the ACE2 receptors. It includes two subunits: S1 and S2.
S1 determines the virus-host range and cellular tropism via the receptor-binding domain.
S2 mediates the membrane fusion of the virus to its potential cell host via the H1 and HR2, which are heptad repeat regions.
Studies have shown that S1 domain induced IgG and IgA antibody levels at a much higher capacity. It is the focus spike proteins expression that are involved in many effective COVID‑19 vaccines.
The M protein is the viral protein responsible for the transmembrane transport of nutrients. It is the cause of the bud release and the formation of the viral envelope. The N and E protein are accessory proteins that interfere with the host's immune response.
Host factors
Human angiotensin converting enzyme 2 (hACE2) is the host factor that SARS-CoV-2 virus targets causing COVID‑19. Theoretically, the usage of angiotensin receptor blockers (ARB) and ACE inhibitors upregulating ACE2 expression might increase morbidity with COVID‑19, though animal data suggest some potential protective effect of ARB; however no clinical studies have proven susceptibility or outcomes. Until further data is available, guidelines and recommendations for people with hypertension remain.
The effect of the virus on ACE2 cell surfaces leads to leukocytic infiltration, increased blood vessel permeability, alveolar wall permeability, as well as decreased secretion of lung surfactants. These effects cause the majority of the respiratory symptoms. However, the aggravation of local inflammation causes a cytokine storm eventually leading to a systemic inflammatory response syndrome.
Among healthy adults not exposed to SARS-CoV-2, about 35% have CD4+ T cells that recognise the SARS-CoV-2 S protein (particularly the S2 subunit) and about 50% react to other proteins of the virus, suggesting cross-reactivity from previous common colds caused by other coronaviruses.
It is unknown whether different persons use similar antibody genes in response to COVID‑19.
Host cytokine response
The severity of the inflammation can be attributed to the severity of what is known as the cytokine storm. Levels of interleukin1B, interferon-gamma, interferon-inducible protein 10, and monocyte chemoattractant protein1 were all associated with COVID‑19 disease severity. Treatment has been proposed to combat the cytokine storm as it remains to be one of the leading causes of morbidity and mortality in COVID‑19 disease.
A cytokine storm is due to an acute hyperinflammatory response that is responsible for clinical illness in an array of diseases but in COVID‑19, it is related to worse prognosis and increased fatality. The storm causes acute respiratory distress syndrome, blood clotting events such as strokes, myocardial infarction, encephalitis, acute kidney injury, and vasculitis. The production of IL-1, IL-2, IL-6, TNF-alpha, and interferon-gamma, all crucial components of normal immune responses, inadvertently become the causes of a cytokine storm. The cells of the central nervous system, the microglia, neurons, and astrocytes, are also involved in the release of pro-inflammatory cytokines affecting the nervous system, and effects of cytokine storms toward the CNS are not uncommon.
Pregnancy response
There are many unknowns for pregnant women during the COVID-19 pandemic. Given that they are prone to have complications and severe disease infection with other types of coronaviruses, they have been identified as a vulnerable group and advised to take supplementary preventive measures.
Physiological responses to pregnancy can include:
Immunological: The immunological response to COVID-19, like other viruses, depends on a working immune system. It adapts during pregnancy to allow the development of the foetus whose genetic load is only partially shared with their mother, leading to a different immunological reaction to infections during the course of pregnancy.
Respiratory: Many factors can make pregnant women more vulnerable to hard respiratory infections. One of them is the total reduction of the lungs' capacity and inability to clear secretions.
Coagulation: During pregnancy, there are higher levels of circulating coagulation factors, and the pathogenesis of SARS-CoV-2 infection can be implicated. The thromboembolic events with associated mortality are a risk for pregnant women.
However, from the evidence base, it is difficult to conclude whether pregnant women are at increased risk of grave consequences of this virus.
In addition to the above, other clinical studies have proved that SARS-CoV-2 can affect the period of pregnancy in different ways. On the one hand, there is little evidence of its impact up to 12 weeks gestation. On the other hand, COVID-19 infection may cause increased rates of unfavourable outcomes in the course of the pregnancy. Some examples of these could be foetal growth restriction, preterm birth, and perinatal mortality, which refers to the foetal death past 22 or 28 completed weeks of pregnancy as well as the death among live-born children up to seven completed days of life. For preterm birth, a 2023 review indicates that there appears to be a correlation with COVID-19.
Unvaccinated women in later stages of pregnancy with COVID-19 are more likely than other people to need very intensive care. Babies born to mothers with COVID-19 are more likely to have breathing problems. Pregnant women are strongly encouraged to get vaccinated.
Diagnosis
COVID‑19 can provisionally be diagnosed on the basis of symptoms and confirmed using reverse transcription polymerase chain reaction (RT-PCR) or other nucleic acid testing of infected secretions. Along with laboratory testing, chest CT scans may be helpful to diagnose COVID‑19 in individuals with a high clinical suspicion of infection. Detection of a past infection is possible with serological tests, which detect antibodies produced by the body in response to the infection.
Viral testing
The standard methods of testing for presence of SARS-CoV-2 are nucleic acid tests, which detects the presence of viral RNA fragments. As these tests detect RNA but not infectious virus, its "ability to determine duration of infectivity of patients is limited". The test is typically done on respiratory samples obtained by a nasopharyngeal swab; however, a nasal swab or sputum sample may also be used. Results are generally available within hours. The WHO has published several testing protocols for the disease.
Several laboratories and companies have developed serological tests, which detect antibodies produced by the body in response to infection. Some have been evaluated by Public Health England and approved for use in the UK.
The University of Oxford's CEBM has pointed to mounting evidence that "a good proportion of 'new' mild cases and people re-testing positives after quarantine or discharge from hospital are not infectious, but are simply clearing harmless virus particles which their immune system has efficiently dealt with" and have called for "an international effort to standardize and periodically calibrate testing" In September 2020, the UK government issued "guidance for procedures to be implemented in laboratories to provide assurance of positive SARS-CoV-2 RNA results during periods of low prevalence, when there is a reduction in the predictive value of positive test results".
Imaging
Chest CT scans may be helpful to diagnose COVID‑19 in individuals with a high clinical suspicion of infection but are not recommended for routine screening. Bilateral multilobar ground-glass opacities with a peripheral, asymmetric, and posterior distribution are common in early infection. Subpleural dominance, crazy paving (lobular septal thickening with variable alveolar filling), and consolidation may appear as the disease progresses. Characteristic imaging features on chest radiographs and computed tomography (CT) of people who are symptomatic include asymmetric peripheral ground-glass opacities without pleural effusions.
Many groups have created COVID‑19 datasets that include imagery such as the Italian Radiological Society which has compiled an international online database of imaging findings for confirmed cases. Due to overlap with other infections such as adenovirus, imaging without confirmation by rRT-PCR is of limited specificity in identifying COVID‑19. A large study in China compared chest CT results to PCR and demonstrated that though imaging is less specific for the infection, it is faster and more sensitive.
Coding
In late 2019, the WHO assigned emergency ICD-10 disease codes U07.1 for deaths from lab-confirmed SARS-CoV-2 infection and U07.2 for deaths from clinically or epidemiologically diagnosed COVID‑19 without lab-confirmed SARS-CoV-2 infection.
Pathology
The main pathological findings at autopsy are:
Macroscopy: pericarditis, lung consolidation and pulmonary oedema
Lung findings:
Minor serous exudation, minor fibrin exudation
Pulmonary oedema, pneumocyte hyperplasia, large atypical pneumocytes, interstitial inflammation with lymphocytic infiltration and multinucleated giant cell formation
Diffuse alveolar damage (DAD) with diffuse alveolar exudates. DAD is the cause of acute respiratory distress syndrome (ARDS) and severe hypoxaemia.
Organisation of exudates in alveolar cavities and pulmonary interstitial fibrosis
Plasmocytosis in bronchoalveolar lavage (BAL)
Blood and vessels: disseminated intravascular coagulation (DIC); leukoerythroblastic reaction, endotheliitis, hemophagocytosis
Heart: cardiac muscle cell necrosis
Liver: microvesicular steatosis
Nose: shedding of olfactory epithelium
Brain: infarction
Kidneys: acute tubular damage.
Spleen: white pulp depletion.
Prevention
Preventive measures to reduce the chances of infection include getting vaccinated, staying at home, wearing a mask in public, avoiding crowded places, keeping distance from others, ventilating indoor spaces, managing potential exposure durations, washing hands with soap and water often and for at least twenty seconds, practising good respiratory hygiene, and avoiding touching the eyes, nose, or mouth with unwashed hands.
Those diagnosed with COVID‑19 or who believe they may be infected are advised by the CDC to stay home except to get medical care, call ahead before visiting a healthcare provider, wear a face mask before entering the healthcare provider's office and when in any room or vehicle with another person, cover coughs and sneezes with a tissue, regularly wash hands with soap and water and avoid sharing personal household items.
The first COVID‑19 vaccine was granted regulatory approval on 2December 2020 by the UK medicines regulator MHRA. It was evaluated for emergency use authorisation (EUA) status by the US FDA, and in several other countries. Initially, the US National Institutes of Health guidelines do not recommend any medication for prevention of COVID‑19, before or after exposure to the SARS-CoV-2 virus, outside the setting of a clinical trial. Without a vaccine, other prophylactic measures, or effective treatments, a key part of managing COVID‑19 is trying to decrease and delay the epidemic peak, known as "flattening the curve". This is done by slowing the infection rate to decrease the risk of health services being overwhelmed, allowing for better treatment of active cases, and delaying additional cases until effective treatments or a vaccine become available.
Vaccine
Face masks and respiratory hygiene
Indoor ventilation and avoiding crowded indoor spaces
The CDC states that avoiding crowded indoor spaces reduces the risk of COVID-19 infection. When indoors, increasing the rate of air change, decreasing recirculation of air and increasing the use of outdoor air can reduce transmission. The WHO recommends ventilation and air filtration in public spaces to help clear out infectious aerosols.
Exhaled respiratory particles can build-up within enclosed spaces with inadequate ventilation. The risk of COVID‑19 infection increases especially in spaces where people engage in physical exertion or raise their voice (e.g., exercising, shouting, singing) as this increases exhalation of respiratory droplets. Prolonged exposure to these conditions, typically more than 15 minutes, leads to higher risk of infection.
Displacement ventilation with large natural inlets can move stale air directly to the exhaust in laminar flow while significantly reducing the concentration of droplets and particles. Passive ventilation reduces energy consumption and maintenance costs but may lack controllability and heat recovery. Displacement ventilation can also be achieved mechanically with higher energy and maintenance costs. The use of large ducts and openings helps to prevent mixing in closed environments. Recirculation and mixing should be avoided because recirculation prevents dilution of harmful particles and redistributes possibly contaminated air, and mixing increases the concentration and range of infectious particles and keeps larger particles in the air.
Hand-washing and hygiene
Thorough hand hygiene after any cough or sneeze is required. The WHO also recommends that individuals wash hands often with soap and water for at least twenty seconds, especially after going to the toilet or when hands are visibly dirty, before eating and after blowing one's nose. When soap and water are not available, the CDC recommends using an alcohol-based hand sanitiser with at least 60% alcohol. For areas where commercial hand sanitisers are not readily available, the WHO provides two formulations for local production. In these formulations, the antimicrobial activity arises from ethanol or isopropanol. Hydrogen peroxide is used to help eliminate bacterial spores in the alcohol; it is "not an active substance for hand antisepsis". Glycerol is added as a humectant.
Social distancing
Social distancing (also known as physical distancing) includes infection control actions intended to slow the spread of the disease by minimising close contact between individuals. Methods include quarantines; travel restrictions; and the closing of schools, workplaces, stadiums, theatres, or shopping centres. Individuals may apply social distancing methods by staying at home, limiting travel, avoiding crowded areas, using no-contact greetings, and physically distancing themselves from others.
In 2020, outbreaks occurred in prisons due to crowding and an inability to enforce adequate social distancing. In the United States, the prisoner population is ageing and many of them are at high risk for poor outcomes from COVID‑19 due to high rates of coexisting heart and lung disease, and poor access to high-quality healthcare.
Surface cleaning
After being expelled from the body, coronaviruses can survive on surfaces for hours to days. If a person touches the dirty surface, they may deposit the virus at the eyes, nose, or mouth where it can enter the body and cause infection. Evidence indicates that contact with infected surfaces is not the main driver of COVID‑19, leading to recommendations for optimised disinfection procedures to avoid issues such as the increase of antimicrobial resistance through the use of inappropriate cleaning products and processes. Deep cleaning and other surface sanitation has been criticised as hygiene theatre, giving a false sense of security against something primarily spread through the air.
The amount of time that the virus can survive depends significantly on the type of surface, the temperature, and the humidity. Coronaviruses die very quickly when exposed to the UV light in sunlight. Like other enveloped viruses, SARS-CoV-2 survives longest when the temperature is at room temperature or lower, and when the relative humidity is low (<50%).
On many surfaces, including glass, some types of plastic, stainless steel, and skin, the virus can remain infective for several days indoors at room temperature, or even about a week under ideal conditions. On some surfaces, including cotton fabric and copper, the virus usually dies after a few hours. The virus dies faster on porous surfaces than on non-porous surfaces due to capillary action within pores and faster aerosol droplet evaporation. However, of the many surfaces tested, two with the longest survival times are N95 respirator masks and surgical masks, both of which are considered porous surfaces.
The CDC says that in most situations, cleaning surfaces with soap or detergent, not disinfecting, is enough to reduce risk of transmission. The CDC recommends that if a COVID‑19 case is suspected or confirmed at a facility such as an office or day care, all areas such as offices, bathrooms, common areas, shared electronic equipment like tablets, touch screens, keyboards, remote controls, and ATMs used by the ill persons should be disinfected. Surfaces may be decontaminated with the following:
62–71% ethanol
50–100% isopropanol
0.1% sodium hypochlorite
0.5% hydrogen peroxide
0.2–7.5% povidone-iodine
50–200 ppm hypochlorous acid
Other solutions, such as benzalkonium chloride and chlorhexidine gluconate, are less effective. Ultraviolet germicidal irradiation may also be used, although popular devices require exposure and may deteriorate some materials over time. A datasheet listing the authorised substances to disinfection in the food industry (including suspension or surface tested, kind of surface, use dilution, disinfectant and inoculum volumes) can be seen in the supplementary material of a 2021 Foods article.
Self-isolation
Self-isolation at home has been recommended for those diagnosed with COVID‑19 and those who suspect they have been infected. Health agencies have issued detailed instructions for proper self-isolation. Many governments have mandated or recommended self-quarantine for entire populations. The strongest self-quarantine instructions have been issued to those in high-risk groups. Those who may have been exposed to someone with COVID‑19 and those who have recently travelled to a country or region with the widespread transmission have been advised to self-quarantine for 14 days from the time of last possible exposure.
International travel-related control measures
A 2021 Cochrane rapid review found that based upon low-certainty evidence, international travel-related control measures such as restricting cross-border travel may help to contain the spread of COVID‑19. Additionally, symptom/exposure-based screening measures at borders may miss many positive cases. While test-based border screening measures may be more effective, it could also miss many positive cases if only conducted upon arrival without follow-up. The review concluded that a minimum 10-day quarantine may be beneficial in preventing the spread of COVID‑19 and may be more effective if combined with an additional control measure like border screening.
Treatment
Prognosis and risk factors
The severity of COVID‑19 varies. The disease may take a mild course with few or no symptoms, resembling other common upper respiratory diseases such as the common cold. In 3–4% of cases (7.4% for those over age 65) symptoms are severe enough to cause hospitalisation. Mild cases typically recover within two weeks, while those with severe or critical diseases may take three to six weeks to recover. Among those who have died, the time from symptom onset to death has ranged from two to eight weeks. The Italian Istituto Superiore di Sanità reported that the median time between the onset of symptoms and death was twelve days, with seven being hospitalised. However, people transferred to an ICU had a median time of ten days between hospitalisation and death. Abnormal sodium levels during hospitalisation with COVID-19 are associated with poor prognoses: high sodium with a greater risk of death, and low sodium with an increased chance of needing ventilator support. Prolonged prothrombin time and elevated C-reactive protein levels on admission to the hospital are associated with severe course of COVID‑19 and with a transfer to ICU.
Some early studies suggest 10% to 20% of people with COVID‑19 will experience symptoms lasting longer than a month. A majority of those who were admitted to hospital with severe disease report long-term problems including fatigue and shortness of breath. On 30 October 2020, WHO chief Tedros Adhanom warned that "to a significant number of people, the COVID virus poses a range of serious long-term effects". He has described the vast spectrum of COVID‑19 symptoms that fluctuate over time as "really concerning". They range from fatigue, a cough and shortness of breath, to inflammation and injury of major organsincluding the lungs and heart, and also neurological and psychologic effects. Symptoms often overlap and can affect any system in the body. Infected people have reported cyclical bouts of fatigue, headaches, months of complete exhaustion, mood swings, and other symptoms. Tedros therefore concluded that a strategy of achieving herd immunity by infection, rather than vaccination, is "morally unconscionable and unfeasible".
In terms of hospital readmissions about 9% of 106,000 individuals had to return for hospital treatment within two months of discharge. The average to readmit was eight days since first hospital visit. There are several risk factors that have been identified as being a cause of multiple admissions to a hospital facility. Among these are advanced age (above 65 years of age) and presence of a chronic condition such as diabetes, COPD, heart failure or chronic kidney disease.
According to scientific reviews smokers are more likely to require intensive care or die compared to non-smokers. Acting on the same ACE2 pulmonary receptors affected by smoking, air pollution has been correlated with the disease. Short-term and chronic exposure to air pollution seems to enhance morbidity and mortality from COVID‑19. Pre-existing heart and lung diseases and also obesity, especially in conjunction with fatty liver disease, contributes to an increased health risk of COVID‑19.
It is also assumed that those that are immunocompromised are at higher risk of getting severely sick from SARS-CoV-2. One research study that looked into the COVID‑19 infections in hospitalised kidney transplant recipients found a mortality rate of 11%.
Men with untreated hypogonadism were 2.4 times more likely than men with eugonadism to be hospitalised if they contracted COVID-19; Hypogonad men treated with testosterone were less likely to be hospitalised for COVID-19 than men who were not treated for hypogonadism.
Genetic risk factors
Genetics plays an important role in the ability to fight off Covid. For instance, those that do not produce detectable type I interferons or produce auto-antibodies against these may get much sicker from COVID‑19. Genetic screening is able to detect interferon effector genes. Some genetic variants are risk factors in specific populations. For instance, an allele of the DOCK2 gene (dedicator of cytokinesis 2 gene) is a common risk factor in Asian populations but much less common in Europe. The mutation leads to lower expression of DOCK2 especially in younger people with severe COVID-19 infections. In fact, many other genes and genetic variants have been found that determine the outcome of SARS-CoV-2 infections.
Children
While very young children have experienced lower rates of infection, older children have a rate of infection that is similar to the population as a whole. Children are likely to have milder symptoms and are at lower risk of severe disease than adults. The CDC reports that in the US roughly a third of hospitalised children were admitted to the ICU, while a European multinational study of hospitalised children from June 2020, found that about 8% of children admitted to a hospital needed intensive care. Four of the 582 children (0.7%) in the European study died, but the actual mortality rate may be "substantially lower" since milder cases that did not seek medical help were not included in the study.
Long-term effects
Around 10% to 30% of non-hospitalised people with COVID-19 go on to develop long COVID. For those that do need hospitalisation, the incidence of long-term effects is over 50%. Long COVID is an often severe multisystem disease with a large set of symptoms. There are likely various, possibly coinciding, causes. Organ damage from the acute infection can explain a part of the symptoms, but long COVID is also observed in people where organ damage seems to be absent.
By a variety of mechanisms, the lungs are the organs most affected in COVID19. In people requiring hospital admission, up to 98% of CT scans performed show lung abnormalities after 28 days of illness even if they had clinically improved. People with advanced age, severe disease, prolonged ICU stays, or who smoke are more likely to have long-lasting effects, including pulmonary fibrosis. Overall, approximately one-third of those investigated after four weeks will have findings of pulmonary fibrosis or reduced lung function as measured by DLCO, even in asymptomatic people, but with the suggestion of continuing improvement with the passing of more time. After severe disease, lung function can take anywhere from three months to a year or more to return to previous levels.
The risks of cognitive deficit, dementia, psychotic disorders, and epilepsy or seizures persists at an increased level two years after infection.
Immunity
The immune response by humans to SARS-CoV-2 virus occurs as a combination of the cell-mediated immunity and antibody production, just as with most other infections. B cells interact with T cells and begin dividing before selection into the plasma cell, partly on the basis of their affinity for antigen. Since SARS-CoV-2 has been in the human population only since December 2019, it remains unknown if the immunity is long-lasting in people who recover from the disease. The presence of neutralising antibodies in blood strongly correlates with protection from infection, but the level of neutralising antibody declines with time. Those with asymptomatic or mild disease had undetectable levels of neutralising antibody two months after infection. In another study, the level of neutralising antibodies fell four-fold one to four months after the onset of symptoms. However, the lack of antibodies in the blood does not mean antibodies will not be rapidly produced upon reexposure to SARS-CoV-2. Memory B cells specific for the spike and nucleocapsid proteins of SARS-CoV-2 last for at least six months after the appearance of symptoms.
As of August 2021, reinfection with COVID‑19 was possible but uncommon. The first case of reinfection was documented in August 2020. A systematic review found 17 cases of confirmed reinfection in medical literature as of May 2021. With the Omicron variant, as of 2022, reinfections have become common, albeit it is unclear how common. COVID-19 reinfections are thought to likely be less severe than primary infections, especially if one was previously infected by the same variant.
Mortality
Several measures are commonly used to quantify mortality. These numbers vary by region and over time and are influenced by the volume of testing, healthcare system quality, treatment options, time since the initial outbreak, and population characteristics such as age, sex, and overall health.
The mortality rate reflects the number of deaths within a specific demographic group divided by the population of that demographic group. Consequently, the mortality rate reflects the prevalence as well as the severity of the disease within a given population. Mortality rates are highly correlated to age, with relatively low rates for young people and relatively high rates among the elderly. In fact, one relevant factor of mortality rates is the age structure of the countries' populations. For example, the case fatality rate for COVID‑19 is lower in India than in the US since India's younger population represents a larger percentage than in the US.
Case fatality rate
The case fatality rate (CFR) reflects the number of deaths divided by the number of diagnosed cases within a given time interval. Based on Johns Hopkins University statistics, the global death-to-case ratio is (/) as of . The number varies by region.
Infection fatality rate
A key metric in gauging the severity of COVID‑19 is the infection fatality rate (IFR), also referred to as the infection fatality ratio or infection fatality risk. This metric is calculated by dividing the total number of deaths from the disease by the total number of infected individuals; hence, in contrast to the CFR, the IFR incorporates asymptomatic and undiagnosed infections as well as reported cases.
Estimates
A December 2020 systematic review and meta-analysis estimated that population IFR during the first wave of the pandemic was about 0.5% to 1% in many locations (including France, Netherlands, New Zealand, and Portugal), 1% to 2% in other locations (Australia, England, Lithuania, and Spain), and exceeded 2% in Italy. That study also found that most of these differences in IFR reflected corresponding differences in the age composition of the population and age-specific infection rates; in particular, the metaregression estimate of IFR is very low for children and younger adults (e.g., 0.002% at age 10 and 0.01% at age 25) but increases progressively to 0.4% at age 55, 1.4% at age 65, 4.6% at age 75, and 15% at age 85. These results were also highlighted in a December 2020 report issued by the WHO.
An analysis of those IFR rates indicates that COVID19 is hazardous not only for the elderly but also for middle-aged adults, for whom the infection fatality rate of COVID-19 is two orders of magnitude greater than the annualised risk of a fatal automobile accident and far more dangerous than seasonal influenza.
Earlier estimates of IFR
At an early stage of the pandemic, the World Health Organization reported estimates of IFR between 0.3% and 1%. On 2July, The WHO's chief scientist reported that the average IFR estimate presented at a two-day WHO expert forum was about 0.6%. In August, the WHO found that studies incorporating data from broad serology testing in Europe showed IFR estimates converging at approximately 0.5–1%. Firm lower limits of IFRs have been established in a number of locations such as New York City and Bergamo in Italy since the IFR cannot be less than the population fatality rate. (After sufficient time however, people can get reinfected). As of 10 July, in New York City, with a population of 8.4 million, 23,377 individuals (18,758 confirmed and 4,619 probable) have died with COVID‑19 (0.3% of the population). Antibody testing in New York City suggested an IFR of ≈0.9%, and ≈1.4%. In Bergamo province, 0.6% of the population has died. In September 2020, the U.S. Centers for Disease Control and Prevention (CDC) reported preliminary estimates of age-specific IFRs for public health planning purposes.
Sex differences
COVID‑19 case fatality rates are higher among men than women in most countries. However, in a few countries like India, Nepal, Vietnam, and Slovenia the fatality cases are higher in women than men. Globally, men are more likely to be admitted to the ICU and more likely to die. One meta-analysis found that globally, men were more likely to get COVID‑19 than women; there were approximately 55 men and 45 women per 100 infections (CI: 51.43–56.58).
The Chinese Center for Disease Control and Prevention reported the death rate was 2.8% for men and 1.7% for women. Later reviews in June 2020 indicated that there is no significant difference in susceptibility or in CFR between genders. One review acknowledges the different mortality rates in Chinese men, suggesting that it may be attributable to lifestyle choices such as smoking and drinking alcohol rather than genetic factors. Smoking, which in some countries like China is mainly a male activity, is a habit that contributes to increasing significantly the case fatality rates among men. Sex-based immunological differences, lesser prevalence of smoking in women and men developing co-morbid conditions such as hypertension at a younger age than women could have contributed to the higher mortality in men. In Europe as of February 2020, 57% of the infected people were men and 72% of those died with COVID‑19 were men. As of April 2020, the US government is not tracking sex-related data of COVID‑19 infections. Research has shown that viral illnesses like Ebola, HIV, influenza and SARS affect men and women differently.
Ethnic differences
In the US, a greater proportion of deaths due to COVID‑19 have occurred among African Americans and other minority groups. Structural factors that prevent them from practising social distancing include their concentration in crowded substandard housing and in "essential" occupations such as retail grocery workers, public transit employees, health-care workers and custodial staff. Greater prevalence of lacking health insurance and care of underlying conditions such as diabetes, hypertension, and heart disease also increase their risk of death. Similar issues affect Native American and Latino communities. On the one hand, in the Dominican Republic there is a clear example of both gender and ethnic inequality. In this Latin American territory, there is great inequality and precariousness that especially affects Dominican women, with greater emphasis on those of Haitian descent. According to a US health policy non-profit, 34% of American Indian and Alaska Native People (AIAN) non-elderly adults are at risk of serious illness compared to 21% of white non-elderly adults. The source attributes it to disproportionately high rates of many health conditions that may put them at higher risk as well as living conditions like lack of access to clean water.
Leaders have called for efforts to research and address the disparities. In the UK, a greater proportion of deaths due to COVID‑19 have occurred in those of a Black, Asian, and other ethnic minority background. More severe impacts upon patients including the relative incidence of the necessity of hospitalisation requirements, and vulnerability to the disease has been associated via DNA analysis to be expressed in genetic variants at chromosomal region 3, features that are associated with European Neanderthal heritage. That structure imposes greater risks that those affected will develop a more severe form of the disease. The findings are from Professor Svante Pääbo and researchers he leads at the Max Planck Institute for Evolutionary Anthropology and the Karolinska Institutet. This admixture of modern human and Neanderthal genes is estimated to have occurred roughly between 50,000 and 60,000 years ago in Southern Europe.
Comorbidities
Biological factors (immune response) and the general behaviour (habits) can strongly determine the consequences of COVID‑19. Most of those who die of COVID‑19 have pre-existing (underlying) conditions, including hypertension, diabetes mellitus, and cardiovascular disease. According to March data from the United States, 89% of those hospitalised had preexisting conditions. The Italian Istituto Superiore di Sanità reported that out of 8.8% of deaths where medical charts were available, 96.1% of people had at least one comorbidity with the average person having 3.4 diseases. According to this report the most common comorbidities are hypertension (66% of deaths), type 2 diabetes (29.8% of deaths), ischaemic heart disease (27.6% of deaths), atrial fibrillation (23.1% of deaths) and chronic renal failure (20.2% of deaths).
Most critical respiratory comorbidities according to the US Centers for Disease Control and Prevention (CDC), are: moderate or severe asthma, pre-existing COPD, pulmonary fibrosis, cystic fibrosis. Evidence stemming from meta-analysis of several smaller research papers also suggests that smoking can be associated with worse outcomes. When someone with existing respiratory problems is infected with COVID‑19, they might be at greater risk for severe symptoms. COVID‑19 also poses a greater risk to people who misuse opioids and amphetamines, insofar as their drug use may have caused lung damage.
In August 2020, the CDC issued a caution that tuberculosis (TB) infections could increase the risk of severe illness or death. The WHO recommended that people with respiratory symptoms be screened for both diseases, as testing positive for COVID‑19 could not rule out co-infections. Some projections have estimated that reduced TB detection due to the pandemic could result in 6.3 million additional TB cases and 1.4 million TB-related deaths by 2025.
History
The virus is thought to be of natural animal origin, most likely through spillover infection. A joint-study conducted in early 2021 by the People's Republic of China and the World Health Organization indicated that the virus descended from a coronavirus that infects wild bats, and likely spread to humans through an intermediary wildlife host. There are several theories about where the index case originated and investigations into the origin of the pandemic are ongoing. According to articles published in July 2022 in Science, virus transmission into humans occurred through two spillover events in November 2019 and was likely due to live wildlife trade on the Huanan wet market in the city of Wuhan (Hubei, China). Doubts about the conclusions have mostly centered on the precise site of spillover. Earlier phylogenetics estimated that SARS-CoV-2 arose in October or November 2019. A phylogenetic algorithm analysis suggested that the virus may have been circulating in Guangdong before Wuhan.
Most scientists believe the virus spilled into human populations through natural zoonosis, similar to the SARS-CoV-1 and MERS-CoV outbreaks, and consistent with other pandemics in human history. According to the Intergovernmental Panel on Climate Change several social and environmental factors including climate change, natural ecosystem destruction and wildlife trade increased the likelihood of such zoonotic spillover. One study made with the support of the European Union found climate change increased the likelihood of the pandemic by influencing distribution of bat species.
Available evidence suggests that the SARS-CoV-2 virus was originally harboured by bats, and spread to humans multiple times from infected wild animals at the Huanan Seafood Market in Wuhan in December 2019. A minority of scientists and some members of the U.S intelligence community believe the virus may have been unintentionally leaked from a laboratory such as the Wuhan Institute of Virology. The US intelligence community has mixed views on the issue, but overall agrees with the scientific consensus that the virus was not developed as a biological weapon and is unlikely to have been genetically engineered. There is no evidence SARS-CoV-2 existed in any laboratory prior to the pandemic.
The first confirmed human infections were in Wuhan. A study of the first 41 cases of confirmed COVID‑19, published in January 2020 in The Lancet, reported the earliest date of onset of symptoms as 1December 2019. Official publications from the WHO reported the earliest onset of symptoms as 8December 2019. Human-to-human transmission was confirmed by the WHO and Chinese authorities by 20 January 2020. According to official Chinese sources, these were mostly linked to the Huanan Seafood Wholesale Market, which also sold live animals. In May 2020, George Gao, the director of the CDC, said animal samples collected from the seafood market had tested negative for the virus, indicating that the market was the site of an early superspreading event, but that it was not the site of the initial outbreak. Traces of the virus have been found in wastewater samples that were collected in Milan and Turin, Italy, on 18 December 2019.
By December 2019, the spread of infection was almost entirely driven by human-to-human transmission. The number of COVID-19 cases in Hubei gradually increased, reaching sixty by 20 December, and at least 266 by 31 December. On 24 December, Wuhan Central Hospital sent a bronchoalveolar lavage fluid (BAL) sample from an unresolved clinical case to sequencing company Vision Medicals. On 27 and 28 December, Vision Medicals informed the Wuhan Central Hospital and the Chinese CDC of the results of the test, showing a new coronavirus. A pneumonia cluster of unknown cause was observed on 26 December and treated by the doctor Zhang Jixian in Hubei Provincial Hospital, who informed the Wuhan Jianghan CDC on 27 December. On 30 December, a test report addressed to Wuhan Central Hospital, from company CapitalBio Medlab, stated an erroneous positive result for SARS, causing a group of doctors at Wuhan Central Hospital to alert their colleagues and relevant hospital authorities of the result. The Wuhan Municipal Health Commission issued a notice to various medical institutions on "the treatment of pneumonia of unknown cause" that same evening. Eight of these doctors, including Li Wenliang (punished on 3January), were later admonished by the police for spreading false rumours and another, Ai Fen, was reprimanded by her superiors for raising the alarm.
The Wuhan Municipal Health Commission made the first public announcement of a pneumonia outbreak of unknown cause on 31 December, confirming 27 casesenough to trigger an investigation.
During the early stages of the outbreak, the number of cases doubled approximately every seven and a half days. In early and mid-January 2020, the virus spread to other Chinese provinces, helped by the Chinese New Year migration and Wuhan being a transport hub and major rail interchange. On 20 January, China reported nearly 140 new cases in one day, including two people in Beijing and one in Shenzhen. Later official data shows 6,174 people had already developed symptoms by then, and more may have been infected. A report in The Lancet on 24 January indicated human transmission, strongly recommended personal protective equipment for health workers, and said testing for the virus was essential due to its "pandemic potential". On 30 January, the WHO declared COVID-19 a Public Health Emergency of International Concern. By this time, the outbreak spread by a factor of 100 to 200 times.
Italy had its first confirmed cases on 31 January 2020, two tourists from China. Italy overtook China as the country with the most deaths on 19 March 2020. By 26 March the United States had overtaken China and Italy with the highest number of confirmed cases in the world. Research on coronavirus genomes indicates the majority of COVID-19 cases in New York came from European travellers, rather than directly from China or any other Asian country. Retesting of prior samples found a person in France who had the virus on 27 December 2019, and a person in the United States who died from the disease on 6February 2020.
RT-PCR testing of untreated wastewater samples from Brazil and Italy have suggested detection of SARS-CoV-2 as early as November and December 2019, respectively, but the methods of such sewage studies have not been optimised, many have not been peer-reviewed, details are often missing, and there is a risk of false positives due to contamination or if only one gene target is detected. A September 2020 review journal article said, "The possibility that the COVID‑19 infection had already spread to Europe at the end of last year is now indicated by abundant, even if partially circumstantial, evidence", including pneumonia case numbers and radiology in France and Italy in November and December.
, Reuters reported that it had estimated the worldwide total number of deaths due to COVID‑19 to have exceeded five million.
The Public Health Emergency of International Concern for COVID-19 ended on May 5, 2023. By this time, everyday life in most countries had returned to how it was before the pandemic.
Misinformation
After the initial outbreak of COVID19, misinformation and disinformation regarding the origin, scale, prevention, treatment, and other aspects of the disease rapidly spread online.
In September 2020, the US Centers for Disease Control and Prevention (CDC) published preliminary estimates of the risk of death by age groups in the United States, but those estimates were widely misreported and misunderstood.
Other species
Humans appear to be capable of spreading the virus to some other animals, a type of disease transmission referred to as zooanthroponosis.
Some pets, especially cats and ferrets, can catch this virus from infected humans. Symptoms in cats include respiratory (such as a cough) and digestive symptoms. Cats can spread the virus to other cats, and may be able to spread the virus to humans, but cat-to-human transmission of SARS-CoV-2 has not been proven. Compared to cats, dogs are less susceptible to this infection. Behaviours which increase the risk of transmission include kissing, licking, and petting the animal.
The virus does not appear to be able to infect pigs, ducks, or chickens at all. Mice, rats, and rabbits, if they can be infected at all, are unlikely to be involved in spreading the virus.
Tigers and lions in zoos have become infected as a result of contact with infected humans. As expected, monkeys and great ape species such as orangutans can also be infected with the COVID‑19 virus.
Minks, which are in the same family as ferrets, have been infected. Minks may be asymptomatic, and can also spread the virus to humans. Multiple countries have identified infected animals in mink farms. Denmark, a major producer of mink pelts, ordered the slaughter of all minks over fears of viral mutations, following an outbreak referred to as Cluster 5. A vaccine for mink and other animals is being researched.
Research
International research on vaccines and medicines in COVID19 is underway by government organisations, academic groups, and industry researchers. The CDC has classified it to require a BSL3 grade laboratory. There has been a great deal of COVID‑19 research, involving accelerated research processes and publishing shortcuts to meet the global demand.
, hundreds of clinical trials have been undertaken, with research happening on every continent except Antarctica. , more than 200 possible treatments have been studied in humans.
Transmission and prevention research
Modelling research has been conducted with several objectives, including predictions of the dynamics of transmission, diagnosis and prognosis of infection, estimation of the impact of interventions, or allocation of resources. Modelling studies are mostly based on compartmental models in epidemiology, estimating the number of infected people over time under given conditions. Several other types of models have been developed and used during the COVID19 pandemic including computational fluid dynamics models to study the flow physics of COVID19, retrofits of crowd movement models to study occupant exposure, mobility-data based models to investigate transmission, or the use of macroeconomic models to assess the economic impact of the pandemic.
Treatment-related research
Repurposed antiviral drugs make up most of the research into COVID‑19 treatments. Other candidates in trials include vasodilators, corticosteroids, immune therapies, lipoic acid, bevacizumab, and recombinant angiotensin-converting enzyme 2.
In March 2020, the World Health Organization (WHO) initiated the Solidarity trial to assess the treatment effects of some promising drugs:
An experimental drug called remdesivir
Anti-malarial drugs chloroquine and hydroxychloroquine
Two anti-HIV drugs, lopinavir/ritonavir and interferon-beta
More than 300 active clinical trials are underway as of April 2020.
Research on the antimalarial drugs hydroxychloroquine and chloroquine showed that they were ineffective at best, and that they may reduce the antiviral activity of remdesivir. , France, Italy, and Belgium had banned the use of hydroxychloroquine as a COVID‑19 treatment.
In June, initial results from the randomised RECOVERY Trial in the United Kingdom showed that dexamethasone reduced mortality by one third for people who are critically ill on ventilators and one fifth for those receiving supplemental oxygen. Because this is a well-tested and widely available treatment, it was welcomed by the WHO, which is in the process of updating treatment guidelines to include dexamethasone and other steroids. Based on those preliminary results, dexamethasone treatment has been recommended by the NIH for peoples with COVID‑19 who are mechanically ventilated or who require supplemental oxygen but not in people with COVID‑19 who do not require supplemental oxygen.
In September 2020, the WHO released updated guidance on using corticosteroids for COVID‑19. The WHO recommends systemic corticosteroids rather than no systemic corticosteroids for the treatment of people with severe and critical COVID‑19 (strong recommendation, based on moderate certainty evidence). The WHO suggests not to use corticosteroids in the treatment of people with non-severe COVID‑19 (conditional recommendation, based on low certainty evidence). The updated guidance was based on a meta-analysis of clinical trials of people critically ill with COVID‑19.
In September 2020, the European Medicines Agency (EMA) endorsed the use of dexamethasone in adults and adolescents from twelve years of age and weighing at least who require supplemental oxygen therapy. Dexamethasone can be taken by mouth or given as an injection or infusion (drip) into a vein.
In November 2020, the US Food and Drug Administration (FDA) issued an emergency use authorisation for the investigational monoclonal antibody therapy bamlanivimab for the treatment of mild-to-moderate COVID‑19. Bamlanivimab is authorised for people with positive results of direct SARS-CoV-2 viral testing who are twelve years of age and older weighing at least , and who are at high risk for progressing to severe COVID‑19 or hospitalisation. This includes those who are 65 years of age or older, or who have chronic medical conditions.
In February 2021, the FDA issued an emergency use authorisation (EUA) for bamlanivimab and etesevimab administered together for the treatment of mild to moderate COVID‑19 in people twelve years of age or older weighing at least who test positive for SARS‑CoV‑2 and who are at high risk for progressing to severe COVID‑19. The authorised use includes treatment for those who are 65 years of age or older or who have certain chronic medical conditions.
In April 2021, the FDA revoked the emergency use authorisation (EUA) that allowed for the investigational monoclonal antibody therapy bamlanivimab, when administered alone, to be used for the treatment of mild-to-moderate COVID‑19 in adults and certain paediatric patients.
Cytokine storm
A cytokine storm can be a complication in the later stages of severe COVID‑19. A cytokine storm is a potentially deadly immune reaction where a large amount of pro-inflammatory cytokines and chemokines are released too quickly. A cytokine storm can lead to ARDS and multiple organ failure. Data collected from Jin Yin-tan Hospital in Wuhan, China indicates that people who had more severe responses to COVID‑19 had greater amounts of pro-inflammatory cytokines and chemokines in their system than people who had milder responses. These high levels of pro-inflammatory cytokines and chemokines indicate presence of a cytokine storm.
Tocilizumab has been included in treatment guidelines by China's National Health Commission after a small study was completed. It is undergoing a PhaseII non-randomised trial at the national level in Italy after showing positive results in people with severe disease. Combined with a serum ferritin blood test to identify a cytokine storm (also called cytokine storm syndrome, not to be confused with cytokine release syndrome), it is meant to counter such developments, which are thought to be the cause of death in some affected people. The interleukin-6 receptor (IL-6R) antagonist was approved by the FDA to undergo a PhaseIII clinical trial assessing its effectiveness on COVID‑19 based on retrospective case studies for the treatment of steroid-refractory cytokine release syndrome induced by a different cause, CAR T cell therapy, in 2017. There is no randomised, controlled evidence that tocilizumab is an efficacious treatment for CRS. Prophylactic tocilizumab has been shown to increase serum IL-6 levels by saturating the IL-6R, driving IL-6 across the blood–brain barrier, and exacerbating neurotoxicity while having no effect on the incidence of CRS.
Lenzilumab, an anti-GM-CSF monoclonal antibody, is protective in murine models for CAR T cell-induced CRS and neurotoxicity and is a viable therapeutic option due to the observed increase of pathogenic GM-CSF secreting Tcells in hospitalised patients with COVID‑19.
Passive antibodies
Transferring purified and concentrated antibodies produced by the immune systems of those who have recovered from COVID‑19 to people who need them is being investigated as a non-vaccine method of passive immunisation. Viral neutralisation is the anticipated mechanism of action by which passive antibody therapy can mediate defence against SARS-CoV-2. The spike protein of SARS-CoV-2 is the primary target for neutralising antibodies. As of 8August 2020, eight neutralising antibodies targeting the spike protein of SARS-CoV-2 have entered clinical studies. It has been proposed that selection of broad-neutralising antibodies against SARS-CoV-2 and SARS-CoV might be useful for treating not only COVID‑19 but also future SARS-related CoV infections. Other mechanisms, however, such as antibody-dependant cellular cytotoxicity or phagocytosis, may be possible. Other forms of passive antibody therapy, for example, using manufactured monoclonal antibodies, are in development.
The use of passive antibodies to treat people with active COVID19 is also being studied. This involves the production of convalescent serum, which consists of the liquid portion of the blood from people who recovered from the infection and contains antibodies specific to this virus, which is then administered to active patients. This strategy was tried for SARS with inconclusive results. An updated Cochrane review in May 2023 found high certainty evidence that, for the treatment of people with moderate to severe COVID‑19, convalescent plasma did not reduce mortality or bring about symptom improvement. There continues to be uncertainty about the safety of convalescent plasma administration to people with COVID‑19 and differing outcomes measured in different studies limits their use in determining efficacy.
Bioethics
Since the outbreak of the COVID‑19 pandemic, scholars have explored the bioethics, normative economics, and political theories of healthcare policies related to the public health crisis. Academics have pointed to the moral distress of healthcare workers, ethics of distributing scarce healthcare resources such as ventilators, and the global justice of vaccine diplomacies. The socio-economic inequalities between genders, races, groups with disabilities, communities, regions, countries, and continents have also drawn attention in academia and the general public.
See also
Coronavirus diseases, a group of closely related syndromes
Disease X, a WHO term
References
Further reading
Scholia Q104287299.
External links
Health agencies
Coronavirus disease (COVID‑19) Facts by the World Health Organization (WHO)
Coronavirus (COVID‑19) by the UK National Health Service (NHS)
Coronavirus 2019 (COVID-19) by the US Centers for Disease Control and Prevention (CDC)
Directories
Coronavirus Resource Center at the Center for Inquiry
COVID‑19 Information on FireMountain.net
COVID‑19 Resource Directory on OpenMD
Medical journals
BMJ's Coronavirus (covid‑19) Hub by the BMJ
Coronavirus (Covid‑19) by The New England Journal of Medicine
Coronavirus (COVID‑19) Research Highlights by Springer Nature
Coronavirus Disease 2019 (COVID‑19) by JAMA
COVID‑19 Resource Centre by The Lancet
Covid‑19: Novel Coronavirus by Wiley Publishing
Novel Coronavirus Information Center by Elsevier
Treatment guidelines
Occupational safety and health
Vaccine-preventable diseases
Viral respiratory tract infections
Zoonoses
Public health
Coronavirus-associated diseases | COVID-19 | [
"Biology"
] | 15,449 | [
"Vaccination",
"Vaccine-preventable diseases"
] |
63,030,703 | https://en.wikipedia.org/wiki/Matching%20in%20hypergraphs | In graph theory, a matching in a hypergraph is a set of hyperedges, in which every two hyperedges are disjoint. It is an extension of the notion of matching in a graph.
Definition
Recall that a hypergraph is a pair , where is a set of vertices and is a set of subsets of called hyperedges. Each hyperedge may contain one or more vertices.
A matching in is a subset of , such that every two hyperedges and in have an empty intersection (have no vertex in common).
The matching number of a hypergraph is the largest size of a matching in . It is often denoted by .
As an example, let be the set Consider a 3-uniform hypergraph on (a hypergraph in which each hyperedge contains exactly 3 vertices). Let be a 3-uniform hypergraph with 4 hyperedges:
Then admits several matchings of size 2, for example:
However, in any subset of 3 hyperedges, at least two of them intersect, so there is no matching of size 3. Hence, the matching number of is 2.
Intersecting hypergraph
A hypergraph is called intersecting if every two hyperedges in have a vertex in common. A hypergraph is intersecting if and only if it has no matching with two or more hyperedges, if and only if .
Matching in a graph as a special case
A graph without self-loops is just a 2-uniform hypergraph: each edge can be considered as a set of the two vertices that it connects. For example, this 2-uniform hypergraph represents a graph with 4 vertices and 3 edges:
By the above definition, a matching in a graph is a set of edges, such that each two edges in have an empty intersection. This is equivalent to saying that no two edges in are adjacent to the same vertex; this is exactly the definition of a matching in a graph.
Fractional matching
A fractional matching in a hypergraph is a function that assigns a fraction in to each hyperedge, such that for every vertex in , the sum of fractions of hyperedges containing is at most 1. A matching is a special case of a fractional matching in which all fractions are either 0 or 1. The size of a fractional matching is the sum of fractions of all hyperedges.
The fractional matching number of a hypergraph is the largest size of a fractional matching in . It is often denoted by .
Since a matching is a special case of a fractional matching, for every hypergraph : Matching-number() ≤ fractional-matching-number()
Symbolically, this principle is written:
In general, the fractional matching number may be larger than the matching number. A theorem by Zoltán Füredi provides upper bounds on the fractional-matching-number() ratio:
If each hyperedge in contains at most vertices, then
In particular, in a simple graph:
The inequality is sharp: Let be the -uniform finite projective plane. Then since every two hyperedges intersect, and by the fractional matching that assigns a weight of to each hyperedge (it is a matching since each vertex is contained in hyperedges, and its size is since there are hyperedges). Therefore the ratio is exactly .
If is such that the -uniform finite projective plane does not exist (for example, ), then a stronger inequality holds:
If is -partite (the vertices are partitioned into parts and each hyperedge contains a vertex from each part), then:
In particular, in a bipartite graph, . This was proved by András Gyárfás.
The inequality is sharp: Let be the truncated projective plane of order . Then since every two hyperedges intersect, and by the fractional matching that assigns a weight of to each hyperedge (there are hyperedges).
Perfect matching
A matching is called perfect if every vertex in is contained in exactly one hyperedge of . This is the natural extension of the notion of perfect matching in a graph.
A fractional matching is called perfect if for every vertex in , the sum of fractions of hyperedges in containing is exactly 1.
Consider a hypergraph in which each hyperedge contains at most vertices. If admits a perfect fractional matching, then its fractional matching number is at least . If each hyperedge in contains exactly vertices, then its fractional matching number is at exactly . This is a generalization of the fact that, in a graph, the size of a perfect matching is .
Given a set of vertices, a collection of subsets of is called balanced if the hypergraph admits a perfect fractional matching.
For example, if and then is balanced, with the perfect fractional matching
There are various sufficient conditions for the existence of a perfect matching in a hypergraph:
Hall-type theorems for hypergraphs - presents sufficient conditions analogous to Hall's marriage theorem, based on sets of neighbors.
Perfect matching in high-degree hypergraphs - presents sufficient conditions analogous to Dirac's theorem on Hamiltonian cycles, based on degree of vertices.
Keevash and Mycroft developed a geometric theory for hypergraph matching.
Balanced set-family
A set-family over a ground set is called balanced (with respect to ) if the hypergraph admits a perfect fractional matching.
For example, consider the vertex set and the edge set is balanced, since there is a perfect fractional matching with weights
Computing a maximum matching
The problem of finding a maximum-cardinality matching in a hypergraph, thus calculating , is NP-hard even for 3-uniform hypergraphs (see 3-dimensional matching). This is in contrast to the case of simple (2-uniform) graphs in which computing a maximum-cardinality matching can be done in polynomial time.
Matching and covering
A vertex-cover in a hypergraph is a subset of , such that every hyperedge in contains at least one vertex of (it is also called a transversal or a hitting set, and is equivalent to a set cover). It is a generalization of the notion of a vertex cover in a graph.
The vertex-cover number of a hypergraph is the smallest size of a vertex cover in . It is often denoted by , for transversal.
A fractional vertex-cover is a function assigning a weight to each vertex in , such that for every hyperedge in , the sum of fractions of vertices in is at least 1. A vertex cover is a special case of a fractional vertex cover in which all weights are either 0 or 1. The size of a fractional vertex-cover is the sum of fractions of all vertices.
The fractional vertex-cover number of a hypergraph is the smallest size of a fractional vertex-cover in . It is often denoted by .
Since a vertex-cover is a special case of a fractional vertex-cover, for every hypergraph :
fractional-vertex-cover-number () ≤ vertex-cover-number ().
Linear programming duality implies that, for every hypergraph :
fractional-matching-number () = fractional-vertex-cover-number().
Hence, for every hypergraph :
If the size of each hyperedge in is at most then the union of all hyperedges in a maximum matching is a vertex-cover (if there was an uncovered hyperedge, we could have added it to the matching). Therefore:
This inequality is tight: equality holds, for example, when contains vertices and contains all subsets of vertices.
However, in general , since ; see Fractional matching above.
Ryser's conjecture says that, in every -partite -uniform hypergraph:
Some special cases of the conjecture have been proved; see Ryser's conjecture.
Kőnig's property
A hypergraph has the Kőnig property if its maximum matching number equals its minimum vertex-cover number, namely if . The Kőnig-Egerváry theorem shows that every bipartite graph has the Kőnig property. To extend this theorem to hypergraphs, we need to extend the notion of bipartiteness to hypergraphs.
A natural generalization is as follows. A hypergraph is called 2-colorable if its vertices can be 2-colored so that every hyperedge (of size at least 2) contains at least one vertex of each color. An alternative term is Property B. A simple graph is bipartite iff it is 2-colorable. However, there are 2-colorable hypergraphs without Kőnig's property. For example, consider the hypergraph with with all triplets It is 2-colorable, for example, we can color blue and white. However, its matching number is 1 and its vertex-cover number is 2.
A stronger generalization is as follows. Given a hypergraph and a subset of , the restriction of to is the hypergraph whose vertices are , and for every hyperedge in that intersects , it has a hyperedge that is the intersection of and . A hypergraph is called balanced if all its restrictions are essentially 2-colorable, meaning that we ignore singleton hyperedges in the restriction. A simple graph is bipartite iff it is balanced.
A simple graph is bipartite iff it has no odd-length cycles. Similarly, a hypergraph is balanced iff it has no odd-length circuits. A circuit of length in a hypergraph is an alternating sequence , where the are distinct vertices and the are distinct hyperedges, and each hyperedge contains the vertex to its left and the vertex to its right. The circuit is called unbalanced if each hyperedge contains no other vertices in the circuit. Claude Berge proved that a hypergraph is balanced if and only if it does not contain an unbalanced odd-length circuit. Every balanced hypergraph has Kőnig's property.
The following are equivalent:
Every partial hypergraph of (i.e., a hypergraph derived from by deleting some hyperedges) has the Kőnig property.
Every partial hypergraph of has the property that its maximum degree equals its minimum edge coloring number.
has the Helly property, and the intersection graph of (the simple graph in which the vertices are and two elements of are linked if and only if they intersect) is a perfect graph.
Matching and packing
The problem of set packing is equivalent to hypergraph matching.
A vertex-packing in a (simple) graph is a subset of its vertices, such that no two vertices in are adjacent.
The problem of finding a maximum vertex-packing in a graph is equivalent to the problem of finding a maximum matching in a hypergraph:
Given a hypergraph , define its intersection graph as the simple graph whose vertices are and whose edges are pairs such that , have a vertex in common. Then every matching in is a vertex-packing in and vice versa.
Given a graph , define its star hypergraph as the hypergraph whose vertices are and whose hyperedges are the stars of the vertices of (i.e., for each vertex in , there is a hyperedge in that contains all edges in that are adjacent to ). Then every vertex-packing in is a matching in and vice versa.
Alternatively, given a graph , define its clique hypergraph as the hypergraph whose vertices are the cliques of , and for each vertex in , there is a hyperedge in containing all cliques in that contain . Then again, every vertex-packing in is a matching in and vice versa. Note that cannot be constructed from in polynomial time, so it cannot be used as a reduction for proving NP-hardness. But it has some theoretical uses.
See also
3-dimensional matching – a special case of hypergraph matching to 3-uniform hypergraphs.
Vertex cover in hypergraphs
Bipartite hypergraph
Rainbow matching in hypergraphs
D-interval hypergraph - an infinite hypergraph in which there is some relation between the matching and the covering number.
Erdős–Ko–Rado theorem on pairwise non-disjoint edges in hypergraphs
References
Hypergraphs
Matching (graph theory) | Matching in hypergraphs | [
"Mathematics"
] | 2,478 | [
"Matching (graph theory)",
"Mathematical relations",
"Graph theory"
] |
63,031,017 | https://en.wikipedia.org/wiki/HD%20101584 | HD 101584 is a suspected post-common envelope binary about 1,800 to 5,900 light-years distant in the constellation of Centaurus. The system is bright at optical wavelengths with an apparent visual magnitude of about 7. The primary is either a post-AGB star, but more likely a post-RGB star. The secondary is a red dwarf or possibly a low-luminosity white dwarf, which orbits the primary every 150-200 days. The system is surrounded by a slowly rotating circumbinary disk, probably with a face-on orientation towards the solar system and a size of about 150 astronomical units.
Variability
In 1991, Jean Manfroid et al. published photometry that showed that HD 101584 is a variable star.
HD 101584 has been given the variable star designation V885 Centauri. The International Variable Star Index states that the star varies between visual magnitude 6.90 and 7.02, over a period of 87.9 days. However Koen and Eyer detected, in the star's Hipparcos data, an oscillation of the star's brightness with a period of 6.744 days and an amplitude of only 0.02 magnitudes.
Nebula
The Hubble Space Telescope image shows a diffuse circumstellar environment with a circular ring around HD 101584. ALMA mapped the nebula around HD 101584 and was able to map the region close to the central binary. The nebula consists of a central compact source, an equatorial density enhancement (disk), a high-velocity bipolar outflow and an hourglass structure surrounding the outflow. The outflow reaches a maximum velocity of about 150 km/s and is inclined to the line of sight by °. There is evidence for a second bipolar outflow with a different orientation from the major outflow. The inner disk, heated to 1540 K, currently has been sublimated by the increasing luminosity of the star.
Evolution
The companion of this system was captured a few hundred years ago, for example when the red giant reached its critical size. It spiralled towards the red giant but stopped before it merged with the core of the primary. During this stage the outer layers of the red giant were ejected. During the common envelope phase the red giant phase of the primary was terminated and the core was revealed. Later, the bipolar jets formed and met the ejected material, forming the hourglass-shaped structure. Ejected material shows prominent spectral features of magnesium, while outer ejected structures contain methanol and formaldehyde.
References
Binary stars
Protoplanetary nebulae
Centauri, V885
046992
IRAS catalogue objects
J11405880-5534258
A-type supergiants
Variable stars
101584
Centaurus | HD 101584 | [
"Astronomy"
] | 568 | [
"Centaurus",
"Constellations"
] |
67,347,207 | https://en.wikipedia.org/wiki/Legion%20Duel%202 | The Lenovo Legion Duel 2, known as the Lenovo Legion 2 Pro in China, is an Android gaming smartphone that was released on April 8, 2021.
Design
The phone features a bump on the back which houses the camera assembly, flash, and dual fans that cool the Qualcomm Snapdragon 888 system-on-a-chip. This bump has been shown to be a weakness. The phone contains dual USB Type C connectors that are used to charge the 5500 mAh battery. The phone comes in both black and white color variations.
References
Mobile phones introduced in 2021
Lenovo Legion
Lenovo smartphones
Mobile phones with multiple rear cameras
Mobile phones with 8K video recording | Legion Duel 2 | [
"Technology"
] | 142 | [
"Mobile technology stubs",
"Mobile phone stubs"
] |
67,348,790 | https://en.wikipedia.org/wiki/National%20Geographical%20Organization%20of%20Iran | The National Geographical Organization of Iran or National Geographical Organization of the Armed Forces of Iran (, or ) is an Iranian government agency affiliated to the Ministry of Defence and Armed Forces Logistics of Iran, which has been established to prepare quick and accurate access spatial information of the country and other areas required by the Armed Forces of Iran.
History
The National Geographical Organization of Iran was officially founded in 1951 to prepare maps and survey geographical activities. Of course, origin of this mapping organization and formation of surveying and cartography branches, was laid in 1921, and in the course of its evolution, it performed responsibilities in accordance with the needs, missions and organizational duties. Finally, it is identified as the National Geographical Organization of Iran or National Geographical Organization of the Armed Forces of Iran. Currently, the National Geographical Organization of Iran, along with the National Cartographic Center, conducts affairs related to surveying and preparation and production of spatial information, but matters related to military maps, national borders and geographical services required by the Armed Forces are performed only through the National Geographical Organization of Iran.
Activities
As the first country in the Middle East, in 1955, the National Geographical Organization of Iran carried out the first analog aerial photography from all over of Iran with a scale of 1: 50,000 and then, using conversion devices (mechanical) and performing engineering steps, was able to prepare and extract topographic maps. Due to the technology conditions that were used at that time, the preparation of the map lasted until 1971 and about 2550 sheets of topographic maps were prepared and produced at a scale of 1: 50,000.
In recent years, the National Geographical Organization of Iran has been able to change the aerial photography system to take the first digital aerial photography with new systems (ULTRA CAM D digital cameras) and done digital aerial photography projects for many cities of Iran.
Among the capabilities and duties of the National Geographical Organization of Iran, the following can be mentioned:
Demarcation of the borders of the country
Production of spatial information in the national and regional areas
Design, implementation and monitoring of satellite and classical geodetic operations
Perform processing, classifying and interpreting aerial and satellite images
Review old maps with different methods of using satellite images and aerial photography
Preparation of thematic and prominent maps and execution of all stages of cartography
Preparation and printing of photo maps (using aerial photographs and satellite images)
Collection and compilation of geographical information
Design and printing (including: typesetting, design, assembly, lithography and printing) types of books and scientific and technical publications
Performing various activities related to remote sensing
implementation of Geographic information system (GIS)
Design and implementation of hydrographic operations
Preparation and construction of scale model from facilities, equipment and natural land features
Design and conversion of all photogrammetric devices from classical (analog) system to analytical and digital system
Holding various advanced courses (theoretical and practical) in the field of surveying engineering
Also, the Surveying Technical School of the Geographical Organization is affiliated with this organization, which present the surveying field in undergraduate and associate degrees.
See also
National Cartographic Center of Iran
Ministry of Defence and Armed Forces Logistics (Iran)
Geology of Iran
National Geoscience Database of Iran
References
External links
National Geographical Organization of Iran on Google Map
Armed Forces Geographical Organization
Examples of the Geographic Services Provided by the Geographical Organization of the Armed Forces of Iran
Ministry of Defence and Armed Forces Logistics of the Islamic Republic of Iran
Geographic data and information organisations in Iran
Geology of Iran
Government agencies of Iran
Technical drawing
Surveying
National mapping agencies | National Geographical Organization of Iran | [
"Engineering"
] | 692 | [
"Surveying",
"Design engineering",
"Technical drawing",
"Civil engineering"
] |
67,349,603 | https://en.wikipedia.org/wiki/Mass%20spectrometry%20at%20Swansea | Swansea University has had a long established history of development and innovation in mass spectrometry and chromatography.
Mass Spectrometry Research Unit
In 1975, John H. Beynon was appointed the Royal Society Research Professor and established the Mass Spectrometry Research Unit at Swansea University (at that time known as the University College of Swansea). In 1986, Dai Games moved from Cardiff University to become the Units new Director.
In 1984, the first observation of He22+ was made at the unit, its the same as molecular hydrogen (isolectronic molecules) except it has lots more energy 3310 kJ per mole.
National Mass Spectrometry Service
A grant of £670,000 was awarded in 1985 by the then Science and Engineering Research Council (SERC) to establish a national Mass Spectrometry Center at Swansea University to provide an analytical service to British Universities. It was officially opened in April 1987 by Lord Callaghan. In 2002, the center was enlarged and the new laboratories were opened by Lord Morgan. Following successful £3,000,000 contract renewal Edwina Hart, the Minister for Economy, Science and Transport, officially re-opened the EPSRC National Research Facility after refurbishment in 2015.
Biomolecular Analysis Mass Spectrometry
A Biomolecular Analysis Mass Spectrometry (BAMS) facility was officially opened in 2003, headed by Professor Newton and Dr Dudley. It was a collaborative entity between the Department of Biological Sciences and the Medical School. It focused on the study of nucleosides, nucleotides and cyclic nucleotides.
Stable isotope mass spectrometry
Stable isotope mass spectrometry is conducted in the Department of Geography, and was recently used by the Landmark Trust to determine very precisely the age of the timber from Llwyn Celyn farmhouse to the year 1420.
References
External links
National Mass Spectrometry Service
EPSRC National Research Facilities
Mass spectrometry
Chromatography
Swansea University | Mass spectrometry at Swansea | [
"Physics",
"Chemistry"
] | 407 | [
"Chromatography",
"Spectrum (physical sciences)",
"Separation processes",
"Instrumental analysis",
"Mass",
"Mass spectrometry",
"Matter"
] |
67,349,932 | https://en.wikipedia.org/wiki/Compagnie%20des%20Autobus%20de%20Monaco | Compagnie des Autobus de Monaco (CAM) is the main public transport operator in Monaco. The company operates 6 regular bus lines, a night service, the Boat-Bus service and several school reinforcements.
History
The Compagnie des Tramways de Monaco (CTM), created in 1897, operated several tramway lines during its existence. The trams circulated for the last time on January 26, 1931, before being replaced by buses. In 1939, the CAM succeeded the network of the former CTM.
In 2019 CAM started collaboration with Canadian company PBSC Solutions Urbaines to provide the Principality with a possibility to get around easily and in an environmentally friendly manner. There are 35 MonaBike stations as of 2020 and if the system works well, other stations will emerge.
CAM's goal by 2030, is to have 100% carbon-free, electric or hydrogen buses.
Routes
There are six bus routes in Monaco, all operated by Compagnie des Autobus de Monaco. There are 143 bus stops through the Principality.
Line 1: Monaco-Ville, Monte-Carlo, Saint Roman and return
Line 2: Monaco-Ville, Monte-Carlo, Exotic Garden and return
Line 4: Place d'Armes, Railway station, Monte-Carlo, Saint Roman and return
Line 5: Railway station, Fontvieille, Hospital and return
Line 6: Larvotto Beach, Fontvieille and return
There are four other bus routes which connect Monaco with neighbouring regions.
Line 11: La Turbie, Monaco and return
Line 100: Nice, Monaco, Menton and return
Line 100X: Nice, Monaco and return
Line 110: Nice Airport, Monaco, Menton and return
There are two night routes.
N1: Albert II - Larvotto Beach and return
N2: Monaco-Ville - Jardin Exotique and return
There is a ferry service "Bateaubus" which operates between both sides of Monaco port. The boat is powered by electricity and operates under the urban bus system tariff.
References
Transport companies established in the 1930s
Transport organizations
Transport in Monaco
International bus transport in Europe | Compagnie des Autobus de Monaco | [
"Physics"
] | 430 | [
"Physical systems",
"Transport",
"Transport organizations"
] |
67,349,962 | https://en.wikipedia.org/wiki/Propagation%20graph | Propagation graphs are a mathematical modelling method for radio propagation channels. A propagation graph is a signal flow graph in which vertices represent transmitters, receivers or scatterers. Edges in the graph model propagation conditions between vertices. Propagation graph models were initially developed by Troels Pedersen, et al. for multipath propagation in scenarios with multiple scattering, such as indoor radio propagation. It has later been applied in many other scenarios.
Mathematical definition
A propagation graph is a simple directed graph with vertex set and edge set .
The vertices models objects in the propagation scenario. The vertex set is split into three disjoint sets as
where is the set of transmitters,
is the set of receivers and
is the set of objects named "scatterers".
The edge set models the propagation models propagation conditions between vertices. Since is assumed simple, and an edge may be identified by a pair of vertices as
An edge is included in if a signal emitted by vertex can propagate to . In a propagation graph, transmitters cannot have incoming edges and receivers cannot have outgoing edges.
Two propagation rules are assumed
A vertex sums the signals impinging via its ingoing edges and remits a scaled version it via the outgoing edges.
Each edge transfers the signal from to scaled by a transfer function.
The definition of the vertex gain scaling and the edge transfer functions can be adapted to accommodate particular scenarios and should be defined in order to use the model in simulations. A variety of such definitions have been considered for different propagation graph models in the published literature.
The edge transfer functions (in the Fourier domain) can be grouped into transfer matrices as
the direct propagation from transmitters to receivers
transmitters to scatterers
scatterers to receivers
scatterers to scatterers,
where is the frequency variable.
Denoting the Fourier transform of the transmitted signal by , the received signal reads in the frequency domain
Transfer function
The transfer function of a propagation graph forms an infinite series
The transfer function is a Neumann series of operators. Alternatively, it can be viewed pointwise in frequency as a geometric series of matrices. This observation yields a closed form expression for the transfer function as
where denotes the identity matrix and is the spectral radius of the matrix given as argument. The transfer function account for propagation paths irrespective of the number of 'bounces'.
The series is similar to the Born series from multiple scattering theory.
The impulse responses are obtained by inverse Fourier transform of
Partial transfer function
Closed form expressions are available for partial sums, i.e. by considering only some of the terms in the transfer function. The partial transfer function for signal components propagation via at least and at most interactions is defined as
where
Here denotes the number of interactions or the bouncing order.
The partial transfer function is then
Special cases:
: Full transfer function.
: Inderect term only.
: Only terms with or fewer bounces are kept (-bounce truncation).
: Error term due to an -bounce truncation.
One application of partial transfer functions is in hybrid models, where propagation graphs are employed to model part of the response (usually the higher-order interactions).
The partial impulse responses are obtained from by the inverse Fourier transform.
Propagation graph models
The propagation graph methodology have been applied in various settings to create radio channel models. Such a model is referred to as a propagation graph model. Such models have been derived for scenarios including
Unipolarized inroom channels. The initial propagation graph models were derived for unipolarized inroom channels.
In a polarimetric propagation graph model is developed for the inroom propagation scenario.
The propagation graph framework has been extended in to time-variant scenarios (such as the vehicle-to-vehicle). For terrestrial communications, where relative velocity of objects are limited, the channel may be assumed quasi-static and the static model may be applied at each time step.
In a number of works including propagation graphs have been integrated into ray-tracing models to enable simulation of reverberation phenomena. Such models are referred to as hybrid models.
Complex environments including outdoor-to-indoor cases. can be studied by taking advantage of the special structure of propagation graphs for these scenarios. Computation methods for obtaining responses for very complex environments have been developed in
The graph model methodology has been used to make spatially consistent MIMO channel models.
Several propagation graph models have been published for high-speed train communications.
Calibration of propagation graph models
To calibrate a propagation graph model, its parameters should be set to reasonable values. Different approaches can be taken.
Certain parameters can be derived from simplified geometry of the room. In particular, reverberation time can be computed via room electromagnetics. Alternatively, the parameters can ben set according to measurement data using inference techniques such as method of moments (statistics), approximate Bayesian computation., or deep neural networks
Related radio channel model types
The method of propagation graph modeling is related to other methods. Noticeably,
Multiple scattering theory
Radiosity
Ray tracing
Geometry-based stochastic channel models (GBSCM)
References
Mathematical modeling | Propagation graph | [
"Mathematics"
] | 1,014 | [
"Applied mathematics",
"Mathematical modeling"
] |
67,351,029 | https://en.wikipedia.org/wiki/Ron%20Cihuat%C3%A1n | Ron Cihuatán is a brand of rum from El Salvador.
History
Licorera Cihuatán S.A. DE C.V., distiller of Cihuatán Rum, was founded in 2004, and is a division of Ingenio La Cabaña, a long established sugar producer. The distillery is located in El Paisnal municipality, El Salvador, and takes its name from a Mayan settlement, now the Cihuatán archaeological site. The company applied for a US trademark in 2014, which was granted in 2016. The first release was an 8 year old rum in 2015, coinciding with their first exports to markets including Lithuania. In 2020 Cihuatán Indigo 8 Years Old Rum won Double Gold in The Fifty Best competition, and also in 2020 the company won Double Gold at the International Spirits Challenge for their rebranding of the Indigo and Cinabrio expressions.
Production
Cihuatán Rum is produced from sugarcane grown in El Salvador and initially processed by parent company Ingenio La Cabaña. The Cihuatán team work with their parent company to select molasses for fermentation and distillation. Cihuatán is distilled in a continuous process using column stills. The rum is matured predominately in former bourbon barrels for at least eight years.
Gabriela Ayala is the brand's master blender.
Products
Cihuatán Jade - matured for 4 years in former bourbon barrels
Cihuatán Indigo - matured for 8 years in former bourbon barrels
Cihuatán Cinabrio - matured for 12 years in former bourbon barrels
Cihuatán Sahumerio - blend of rums matured for between 12 and 14 years
Cihuatán Alux - matured for 15 years, finished in oloroso sherry and cognac casks
Cihuatán Xaman XO - initially matured for 15 years in former bourbon barrels, before finishing for one year in Mayan Ceiba barrels.
References
External links
Cihuatán Rum website
Ingenio La Cabaña website
Rum brands
Distilleries
Salvadoran brands
Rum produced in El Salvador | Ron Cihuatán | [
"Chemistry"
] | 431 | [
"Distilleries",
"Distillation"
] |
67,352,181 | https://en.wikipedia.org/wiki/Tenilapine | Tenilapine is an atypical antipsychotic which has never been marketed in the US.
Pharmacodynamics
Tenilapine has a relatively high affinity for the 5-HT2A receptor, and relatively low (micromolar) affinities for dopamine receptors.
The ratio of D2 to D4 bonding is similar to that of clozapine. Like many other atypical antipsychotics, it is a potent 5-HT2C antagonist.
References
4-Methylpiperazin-1-yl compounds
5-HT2A antagonists
5-HT2B antagonists
Atypical antipsychotics
Heterocyclic compounds with 3 rings
M1 receptor antagonists
M2 receptor antagonists
M3 receptor antagonists
M4 receptor antagonists
M5 receptor antagonists
Nitriles
Thiophenes | Tenilapine | [
"Chemistry"
] | 179 | [
"Nitriles",
"Functional groups"
] |
67,352,502 | https://en.wikipedia.org/wiki/Nano%20tape | Nano tape, also called gecko tape is a synthetic adhesive tape consisting of arrays of carbon nanotubes transferred onto a backing material of flexible polymer tape. These arrays are called synthetic setae and mimic the nanostructures found on the toes of a gecko; this is an example of biomimicry. The adhesion is achieved not with chemical adhesives, but via van der Waals forces, which are weak electric forces generated between two atoms or molecules that are very close to each other.
Explanation
Geckos show a remarkable ability to climb smooth vertical surfaces at high speeds, exhibiting both strong attachment and easy rapid removal, or shear adhesion, of their feet.
On a gecko's foot, micrometer-sized elastic hairs called setae are split into nanometer-sized structures called spatulas. The shear adhesion is achieved by forming and breaking van der Waals forces between these microscopic structures and the substrate.
Nano tapes mimic these structures with carbon nanotube bundles, which simulate setae and individual nanotubes, which simulate spatulas, to achieve macroscopic shear adhesion and to translate the weak van der Waals interactions into high shear forces. The shear adhesion allows the tape to be easily peeled off in the manner a gecko lifts its foot. Since the carbon nanotube arrays leave no residue on the substrate, the tape can be reused many times.
History
Nano tape is one of the first developments of synthetic setae, which arose from a collaboration between the Manchester Centre for Mesoscience and Nanotechnology, and the Institute for Microelectronics Technology in Russia. Work started in 2001 and two years later results were published in Nature Materials.
The group prepared flexible fibers of polyimide as the synthetic setae structures on the surface of a 5 μm thick film of the same material using electron beam lithography and dry etching in an oxygen plasma. The fibres were 2 μm long, with a diameter of around 500 nm and a periodicity of 1.6 μm, and covered an area of roughly 1 cm2 (see figure on the left). Initially, the team used a silicon wafer as a substrate, but found that the tape's adhesive power increased by almost 1,000 times if they used a soft bonding substrate such as Scotch tape. This is because the flexible substrate yields a much higher ratio of the number of setae in contact with the surface over the total number of setae.
The result of this "gecko tape" was tested by attaching a sample to the hand of a 15 cm high plastic Spider-Man figure weighing 40 g, which enabled it to stick to a glass ceiling, as is shown in the figure. The tape, which had a contact area of around with the glass, was able to carry a load of more than . However, the adhesion coefficient was only 0.06, which is low compared with real geckos (8~16).
Commercial use
Commercial nano tape is usually sold as double-sided tape that is useful for hanging lightweight items, such as pictures and decorative items on smooth walls. Using superaligned carbon nanotubes, some nano tapes can stay sticky in extreme temperatures.
Gallery
References
Adhesive tape
Biophysics
Biomimetics
Nanotechnology
Carbon nanotubes | Nano tape | [
"Physics",
"Materials_science",
"Engineering",
"Biology"
] | 679 | [
"Biological engineering",
"Applied and interdisciplinary physics",
"Bionics",
"Materials science",
"Bioinformatics",
"Biophysics",
"Nanotechnology",
"Biomimetics"
] |
67,352,625 | https://en.wikipedia.org/wiki/H.%20E.%20Watson | Herbert Edmeston Watson (17 May 1886 - 24 September 1980) was Ramsay Memorial Professor of Chemical Engineering at University College London and the inventor of the low voltage neon glow lamp.
Education
Watson attended Marlborough School. He completed a Bachelor of Science in chemistry at University College London in 1908 under the tutorship of Sir William Ramsay. In Watson's notes from Ramsay Intermediate Lectures in 1904-05 he said of Ramsay:
While under Ramsay, Watson worked with him on "The refraction and dispersion of neon", while Ramsay presented Watson's work "The spectrum of the lighter constituents of the air" to the Royal Society in 1908, and "The spectrum of radium emanation" to the Royal Society in 1909. Also while at UCL, Watson modified Chick's Law, the relationship between the kill efficiency of organisms and contact time with a disinfectant, that had been created by Harriette Chick, by including the coefficient of specific lethality. The 1908 amendment is known as The Chick-Watson Equation.
Watson studied for his Doctor of Science at several institutions. In 1909 he studied at the University of Berlin under Walter Nernst. During 1910 he was at the University of Geneva under Philippe-Auguste Guye, completing his studies at the Trinity College, Cambridge under Joseph John Thomson in 1911. During this time he was awarded the 1851 Exhibition Scholarship. At Cambridge, he created the first low voltage neon glow lamp which worked at . Thomson presented the work of Watson and Francis William Aston to the Royal Academy in 1912, and Watson' s work on "Some experiments on the electrical discharge in helium and neon" to the Cambridge Philosophical Society. He graduated from his Doctor of Science at University College London in 1912.
Career
In 1911 he joined the Indian Institute of Science in Bangalore as an associate professor, before progressing to the role of Professor of Inorganic and Physical Chemistry at the Institute in 1916. During 1916, Watson and J. J. Sudborough successfully extracted the first sample of sandalwood oil in India at the institute. He resigned from the role in 1933, after the new director of the Institute, Sir C. V. Raman, started to redirect funds from the chemistry department to physics.
In 1934 he became the third Ramsay professor of chemical engineering at University College London after the death of the previous incumbent W. E. Gibbs, and held the position until his retirement in 1951. At the end of the war, Watson fell out with Professor of Chemistry Ingold over the quality of delivery of chemistry to chemical engineering students, which was resolved by Watson hiring his own chemistry lecturer. Upon his retirement he was made Emeritus Professor at UCL, being replaced by M. B. Donald as the Ramsay professor. In 1961, he wrote the paper "The development of the neon glow lamp (1911–61)" which appeared in Nature.
Personal life and death
Watson was born to Arthur Edmeston Watson and Helen Louisa Rumpff, in Kew on the 17 May 1886. He married Kathleen Margaret Rowson in 1917, who died in 1951, and had one son Bruce Edmeston Watson in 1918. Watson died on the 24 September 1980 in Woking.
References
1886 births
1980 deaths
Alumni of University College London
Alumni of Trinity College, Cambridge
Academics of University College London
British chemical engineers
Chemical engineering academics
Fellows of the Institution of Chemical Engineers
Academic staff of the Indian Institute of Science | H. E. Watson | [
"Chemistry"
] | 685 | [
"Chemical engineering academics",
"Chemical engineers"
] |
67,352,985 | https://en.wikipedia.org/wiki/Feminist%20design | Feminist design refers to connections between feminist perspectives and design. Feminist design can include feminist perspectives applied to design disciplines like industrial design, graphic design and fashion design, and parallels work like feminist urbanism, feminist HCI and feminist technoscience. Feminist perspectives can touch any aspect of the design project including processes, artifacts and practitioners.
History
There is a long history of feminist activity in design. Early examples include movements for dress reform (mid–19th century) and concepts for utopian feminist cities (late 19th century to the early 20th century). Over time this work has explored topics like beauty, DIY, feminine approaches to architecture, community-based and grassroots projects, among many examples. Some iconic writing includes Cheryl Buckley's essays on design and patriarchy and Judith Rothschild's Design and feminism: Re-visioning spaces, places, and everyday things.
Scope
Some scholars suggest that all designers should be feminists, as drawn by Chimamanda Ngozi Adichie, approaching feminism not only through gender but through power.
“Not surprisingly, feminist approaches to design have generally been concerned with the relationship between women and design-how they are affected by it and how their contributions to it are regarded. These two inquiries have been thoroughly investigated in existing literature. Historically, they tended to be based on universal accounts of women, which assumed a cisgender, white, heterosexual, able-bodied woman. Only recently has the work expanded to advance our under- standing of the ways in which the impacts of design are felt at the intersections of gender and race, class, and other identities. Most feminist discourse in design seems to imply that the problems raised would not be problems if more designers were women and if their perspectives were valued.”
Feminist insights for design
Isabel Prochner's research explored how feminist perspectives can support positive change in industrial design. She stressed the diversity of feminist perspectives, but also argued that they can help identify systemic social problems and inequities in design and guide socially sustainable and grassroots design solutions. She wrote that feminist perspectives in industrial design often support:
"Emphasizing human life and flourishing over output and growth
Following best practices in labor/ international production /trade
Choosing an empowering workspace
Engaging in non-hierarchical/ interdisciplinary/ collaborative work
Addressing user needs at multiple levels, including support for pleasure/ fun/ happiness
Creating thoughtful products for female users
Creating good jobs through production/ execution/ sale of the design solution"
Related pages
Design justice
FeministDesign.co
Dolores Hayden
Intersectionality
Data feminism
Nina Paim
Futuress
Cyberfeminism
Bibliography
References
Feminism and society
Design | Feminist design | [
"Engineering"
] | 519 | [
"Design"
] |
67,353,049 | https://en.wikipedia.org/wiki/USA-198 | USA-198, known before launch as NRO Launch 24 (NROL-24), is an American communications satellite that was launched in 2007.
Launch
United Launch Alliance (ULA) performed the launch of USA-198 using an Atlas V rocket in the 401 configuration from SLC-41 of the Cape Canaveral Space Force Station at 22:05 UTC on December 10, 2007.
References
Spacecraft launched in 2007
Spacecraft launched by Atlas rockets
Satellites of the United States | USA-198 | [
"Astronomy"
] | 96 | [
"Astronomy stubs",
"Spacecraft stubs"
] |
67,353,527 | https://en.wikipedia.org/wiki/Introgressive%20hybridization%20in%20plants | Introgressive hybridization, also known as introgression, is the flow of genetic material between divergent lineages via repeated backcrossing. In plants, this backcrossing occurs when an generation hybrid breeds with one or both of its parental species.
Source of variation
Although some genera of plants hybridize and introgress more easily than others, in certain scenarios, external factors may contribute to an increased rate of hybridization. The phenomenon known as Hybridization of the Habitat echoes this idea, explaining that disturbances in a natural habitat can lead to species which typically do not hybridize and backcross to do so with relative ease. Plant breeders also manipulate their subjects to hybridize in order to optimize their hardiness, appearance, or whatever desired traits they want to select for. This type of hybridization has been particularly impactful for the production of many crop species, including but not limited to: certain types of rice, corn, wheat, barley, and rye. Natural introgression can occur with many genera and species, but manipulating the gene pool with artificial/forced introgression is useful for honing in on desired characteristics, such as drought tolerance or pest resistance.
Background
In the early days of hybrid research, it was commonly believed that there was insufficient evidence of hybridization in nature because hybridization would mostly produce sterile or unfit offspring. Through experimentation and improved phylogenetic testing capabilities, we now see that the ability to produce fertile hybrid offspring varies by genus, within the plant kingdom. A few examples of species with the capacity to produce fertile hybrids are given below.
Examples of natural introgression
Irises
One of the most significant early studies of plant hybridization involved three species of irises. Although they commonly form crosses where their natural habitats overlap, there is no evidence that Iris fulva, Iris hexagona, or Iris brevicaulis are closely related and their phenotypic differences (color/pattern/size) are distinct. Once introgression occurs, the resulting offspring display a wide array of color combinations, as well as varying flower size. Iris fulva shows a tendency for asymmetrical introgression, where it transfers more genetic material into hybrid offspring than either Iris hexagona or Iris brevicaulis.
Sunflowers
Differential introgression of chloroplasts and nuclear genomes was first seen among the common sunflower (Helianthus annuus ssp. texanus). Within a particular region, the population showed differences in morphological features which indicated there may be hybridization with H. debilis ssp cucumenifolius. Researchers discovered that these H. a. texanus contained chloroplast DNA from H. d. cucumennfolius, indicating introgression had occurred in one direction.
Poplars
Hybridization among poplars is common where ever populations overlap, however the degree of introgression varies greatly depending on the species. One study exploring the extent of introgression among three species of poplar trees (P. balsamifera, P. angustifolia and P. trichocarpa) conducted along the Rock Mountain range in the U.S. and Canada found extensive introgression in areas of species converge. Genomic sequencing even showed a trispecies hybrid in these overlapping areas. Another study found a hybrid zone in Utah where there was a unidirectional flow of introgression between P. angustifolia and P. fremontii.
Examples of artificial introgression
Wheat
Introgression has played a major role in the development of wheat for crop production. One of the ways crop species can be manipulated is by crossing them with wild type species. For instance, the wild wheat relative species Agropyron elongatum has been crossed and introgressed with the domesticated wheat Triticum aestivum. Consequently, the resulting hybrids have a higher water stress adaptation and higher root and shoot biomass. Both of these modifications can improve the fitness of the crop.
Daffodils
Daffodils (genus Narcissus) are able to produce semi-fertile or fertile offspring, even from wide crosses. The ability of daffodils, such as the yellow trumpet Narcissi and Poets’ Narcissi to hybridize and backcross allows for the vast variety of options modern-day gardeners have to select from. Although daffodils do hybridize and introgress in nature, artificial introgression allows for breeders to take species that are geographically separated and make unique crosses that would not appear naturally.
References
Hybridisation (biology)
Plants | Introgressive hybridization in plants | [
"Biology"
] | 939 | [
"Plants"
] |
67,354,408 | https://en.wikipedia.org/wiki/Zero%20register | A zero register is a processor register that always returns the value zero and has no effect when it is written to. It is found in instruction set architectures including the CDC 6600, System/360 and ARM64, among others.
Zero appears as a constant in many instructions, notably "branch if zero", and optimizing these instructions can have a positive benefit on performance. Some architectures accomplish this with dedicated opcodes, specialized variations of their basic instructions. Implementing these requires additional logic in the instruction decoder. The zero register can accomplish the same effect without requiring new opcodes, although at the cost of dedicating a register to this feature, which may have negative impact for architectures with limited number of registers.
The x86 architecture has no zero register, ARM added a zero register for ARM64. The RISC-V architecture includes one with the register name "x0" and the ABI name "zero"; the reason for this inclusion is stated as "Dedicating a register to zero is surprisingly a large factor in simplifying the RISC-V ISA.
note: this is different to zeroing a register such as by xor as it uses phisical harware
"
References
Digital registers | Zero register | [
"Technology"
] | 252 | [
"Computing stubs",
"Computer hardware stubs"
] |
67,354,487 | https://en.wikipedia.org/wiki/Park%20of%20Generous%20Souls | The Park of Generous Souls () is a park in Zvolen, Slovakia dedicated to Slovak citizens who helped save Jews during the Holocaust.
References
Zvolen
Rescue of Jews during the Holocaust
Holocaust memorials | Park of Generous Souls | [
"Biology"
] | 42 | [
"Rescue of Jews during the Holocaust",
"Behavior",
"Altruism"
] |
67,355,372 | https://en.wikipedia.org/wiki/Chloracyzine | Chloracyzine is an antidepressant and coronary vasodilator of the phenothiazine class, invented in Russia and used as an anti-anginal agent. It was found not to have antipsychotic activity, but was instead the first Russian tricyclic drug with antidepressant action.
See also
List of Russian drugs
References
Amides
Chloroarenes
Phenothiazines
Russian drugs
Tertiary amines
Tricyclic antidepressants
Vasodilators | Chloracyzine | [
"Chemistry"
] | 109 | [
"Amides",
"Functional groups"
] |
67,357,614 | https://en.wikipedia.org/wiki/Chromium%28IV%29%20silicide | Chromium(IV) silicide or chromium monosilicide is an inorganic compound of chromium and silicon with a chemical formula of CrSi. It is a metal with an electrical resistivity of ca. 2 Ω·cm.
References
Chromium(IV) compounds
Group 6 silicides
Iron monosilicide structure type | Chromium(IV) silicide | [
"Chemistry"
] | 72 | [
"Inorganic compounds",
"Inorganic compound stubs"
] |
67,357,922 | https://en.wikipedia.org/wiki/Trichromium%20silicide | Trichromium silicide is an inorganic compound of chromium and silicon with the chemical formula Cr3Si.
References
Chromium compounds
Group 6 silicides | Trichromium silicide | [
"Chemistry"
] | 37 | [
"Inorganic compounds",
"Inorganic compound stubs"
] |
67,358,788 | https://en.wikipedia.org/wiki/Galperin%20configuration | Galperin configuration are a particular configuration of sensing elements found in a class of seismic instruments measuring ground motion and are named after Soviet seisomologist Evsey Iosifovich Galperin, who introduced it in 1955 for petroleum exploration.
Description
Common triaxial seismometers provide signal outputs in three orthogonal axes oriented towards east–west (E), north–south (N) and up-down (Z), i.e. in the Cartesian coordinate system. In contrast, the Galperin configuration consists of three orthogonal axes (U, V, W) that are oriented at precisely the same angle with respect to the horizontal plane (α=35.26°). The projection of all three axes onto the horizontal plane are all separated by 120°, which results in the "symmetric triaxial" design. The recordings acquired with the Galperin configuration are brought to the Cartesian coordinate system by the following coordinate transformation, where β=30°:
A main advantage of the Galperin configuration is that all three receivers have identical orientation with respect to the vertical axis and, thus have identical instrument responses. Another advantage is the ability to build smaller packages (i.e., instruments) compared to the Cartesian orientation, which makes the Galperin configuration especially applicable for borehole installations. Other benefits of the Galperin configuration include easier distinction between external and internal noise sources and the fact that the configuration is not sensitive to rotation around the vertical axis. However, the main drawback of the configuration is that all input vectors are linked by the rotational matrix, which causes failure of the entire system when one of the three sensor is malfunctioning. In the Cartesian configuration, for example, both horizontal components still provide useful data in case the vertical (Z) component fails.
The Galperin configuration found wide application in seismometer design, including models for borehole, ocean bottom, and vault installations. The Galperin configuration can also be applied at the source side to simulate three-component seismic sources
References
Seismology instruments
Seismology measurement
Soviet inventions | Galperin configuration | [
"Technology",
"Engineering"
] | 427 | [
"Seismology instruments",
"Measuring instruments"
] |
67,359,130 | https://en.wikipedia.org/wiki/Manganese%20arsenide | Manganese arsenide (MnAs) is an intermetallic compound, an arsenide of manganese. It forms ferromagnetic crystals with hexagonal (NiAs-type) crystal structure, which convert to the paramagnetic orthorhombic β-phase upon heating to . MnAs has potential applications in spintronics, for electrical spin injection into GaAs and Si based devices.
References
Manganese compounds
Arsenides
Nickel arsenide structure type
Ferromagnetic materials | Manganese arsenide | [
"Physics"
] | 108 | [
"Materials",
"Ferromagnetic materials",
"Matter"
] |
67,360,148 | https://en.wikipedia.org/wiki/Tris%282-phenylpyridine%29iridium | Tris(2-phenylpyridine)iridium, abbreviated [Ir(ppy)3] is the organoiridium complex with the formula Ir(C6H4-C5H4N)3. The complex, a yellow-green solid, is a derivative of Ir3+ bound to three monoanionic 2-pyridinylphenyl ligands. It is electroluminescent, emitting green light. The complex is observed with the facial stereochemistry, which is chiral.
The complex is prepared by cyclometalation reactions of 2-phenylpyridine and iridium trichloride, as represented by this idealized equation:
IrCl3 + 3C6H5-C5H4N → Ir(C6H4-C5H4N)3 + 3 HCl
The complex and many analogues have been investigated for application in photoredox catalysis. Its excited state has a reduction potential of −2.14 V, nearly 1 V more negative than the reduction potential of excited [Ru(bipy)3]2+.
References
2-Pyridyl compounds
Photochemistry
Organoiridium compounds | Tris(2-phenylpyridine)iridium | [
"Chemistry"
] | 252 | [
"nan"
] |
67,360,470 | https://en.wikipedia.org/wiki/Suckerin | Suckerins are a type of block copolymer protein that forms the teeth of sucker rings and beaks of cephalopods. These biopolymers form exhibit high elastic modulus and thermoplastic behavior.
Properties
Suckerin proteins have a size range from 5-60kDA with an isoelectric point of pl 7–10.
Applications
Suckerin has a structure similar to spider silk. In the future it could be used to make medical tools, specialty bandages, sutures and artificial ligaments. Additionally, it could be used for commercial and industrial products such as well as body armor, parachutes, sails and airplane components.
References
Structural proteins
Molluscan proteins | Suckerin | [
"Chemistry"
] | 140 | [
"Polymer stubs",
"Organic chemistry stubs"
] |
67,361,137 | https://en.wikipedia.org/wiki/PharmEasy | PharmEasy is an Indian e-pharmacy company that sells medicines, diagnostics and telehealth online.
History
The company was founded in 2015 by Dharmil Sheth and Dhaval Shah in Mumbai with the initial seed funding provided by their parents. The company wanted to expand beyond the Mumbai market and received their Series A funding.
In May 2021, PharmEasy acquired rival e-pharmacy company Medlife for an undisclosed amount. In June 2021, the company acquired a 66.1% stake in diagnostics chain Thyrocare for . In September 2021, it acquired a majority stake in Aknamed, a healthcare supply chain company.
In November 2021, the company filed papers to launch its initial public offering (IPO) of . The company withdrew its IPO plans in August 2022.
Competition
PharmEasy competes with other e-pharmacy companies including Netmeds (which was acquired by Reliance Industries), 1mg (acquired by Tata Group), Apollo 24x7 and Amazon Pharmacy. The Ken questioned the company's positioning as a unified healthtech player and referred to the company's story as "more confusing than convincing".
Criticism
Medlife–PharmEasy merger protests
In 2020, PharmEasy and Medlife were in merger talks which came to the attention of the Competition Commission of India (CCI), which approves such mergers. The merger was protested by The South Chemist and Distributors Association (SCDA), who objected that sales of medicines online was illegal in India. The online sales of medicines was later regulated and the merger was completed in 2021.
PharmEasy advertisement
Members of the Hindu religion criticized one of the company's advertisements and said that religious sentiments were hurt for the sake of marketing and sales. The advertisement in question showed Lakshman being struck and Ram needing Sanjeevani, asking who will bring the medicine from such a long distance. Two PharmEasy employees arrive by scooter to deliver it.
References
Indian companies established in 2015
Retail companies established in 2015
Internet properties established in 2015
E-commerce
Companies based in Mumbai | PharmEasy | [
"Technology"
] | 429 | [
"Information technology",
"E-commerce"
] |
67,361,364 | https://en.wikipedia.org/wiki/Anthony%20Mahowald | Anthony Mahowald (born November 24, 1932) is a molecular genetics and cellular biologist who served as the department chair of the molecular genetics and cellular biology department at the University of Chicago. His lab focused on the fruit fly Drosophila melanogaster, specifically focusing on controlling the genetic aspects of major developmental events. His major research breakthroughs included the study of the stem cell niche, endocycles, and various types of actin.
Personal life
Anthony Mahowald is married and has three children.
Educational career
Anthony Mahowald was born in Albany, Minnesota, on November 24, 1932. Mahowald received a bachelor's degree from Spring Hill College in Mobile, Alabama. Following his undergraduate studies, Mahowald earned his Ph.D. from Johns Hopkins University in 1962. At Johns Hopkins, Mahowald studied the structure of pole cells and polar granules in Drosophila melanogaster. Both his undergraduate and doctoral degrees were in the field of biology.
Professional career
Mahowald has worked in many universities in his academic career. From 1972 to 1982, he started his career at Marquette University, while also working for the Institute of Cancer Research in Philadelphia, Pennsylvania. Then, he accepted a position at Indiana University from 1972 to 1982. He then moved on to Case Western Reserve University from 1982 to 1990. Finally, from 1990 to 2002, Mahowald was employed at the University of Chicago as the department chair for molecular genetics and cellular biology. In 2002, he retired from academia and currently works as an emeritus at the University of Chicago.
Awards and associations
Mahowald is a member of a wide range of prestigious organizations. He is a part of the American Association for the Advancement of Science, Society of Scholars at Johns Hopkins University, American Academy of Arts and Sciences, the Woodrow Wilson Foundation, the Genetics Society of America, the American Society of Cell Biology, the Society of Developmental Biology, and the National Academy of Science.
Research and scientific contributions
The majority of his research centered around the common fruit fly and other insects for developmental and genetic studies.
One of Malhowald's groundbreaking articles involve the study of the stem cell niche, which is a specialized environment where adult stem cells reside in some insects and amphibians. This area helps to keep stem cells in an undifferentiated state through short-range signaling. Mahowald discovered that this area, and specifically the e-cadherin-based stem cell adhesion, is vital in maintaining the Drosophila germline stem cells. These stem cells are important to the reproduction of Drosophila as they turn into sperm cells. In Drosophila testicles, the Leukocyte-antigen-related (LAR) receptor tyrosine phosphatase targets selection and synapse formation with nerve cells. After testing, it was discovered that the receptor expression is increased in the analysis of testicles containing higher numbers of early germ cells and cyst cells. After analysis of this data and further testing of his own, Mahowald discovered that the LAR expressed in the testicles retains germline stem cells at the niche through the increased E-cadherin-based adhesion.
Some of Mahowald's most recent work centers around the study of endocycles. These are cell cycles that do not have a mitotic phase. In other words, cells continuously duplicate their genetic information without division into two cells. This creates very large cells, but their genetic information cannot be organized and separated into chromosomes due to inhibition of cyclin-dependent kinase activity. Mahowald discovered pre-mitotic endocycles in rectal non-cancerous polyploid cells in Drosophila. The endocycling creates a polyploid cell, and these polyploid have high error-rates, suggesting that there will be an accumulation of cells with incorrect number of chromosomes. He argues that pre-mitotic endocycling is essential for non-cancerous polyploid development, specifically in papillary development. While organisms would die from the accumulation of aneuploid, Mahowald found that, in this instance, significant changes in survival rates were not observed. Thus, he and his team directly disproved previous thoughts that aneuploidy decreases survivability in various insects, especially flies.
Mahowald also studied the actin and the various genes that code for very similar types of actin in an organism. Mahowald was concerned as to why organisms have multiple, very similar, genes that encode for the same proteins with only a few amino acids different. To attempt to answer this question, Mahowald and team isolated two actin genes, Act42A and Act5C, with only two amino acids being different between the two genes, and both are present in all cells in the Drosophila during development.
Other researchers had established that multiple isoforms are crucial for development. It was determined that the small differences make actin filaments that do have different functions, such as cytoplasmic functions and muscular functions. Indeed, Mahowald established that there is a need for multiple forms of actin due to the large quantity of actin needed in a cell, along with the fact that some cells have different microfilament-based needs. However, he set out to determine if these actin filaments could be interchanged due to their similarity in structure.
Mahowald focused on cytoplasmic actin genes instead of muscular actin due to the multifunctional nature of cytoplasmic actin when compared to muscular actin. Using genomic DNA and Reverse Transcription PCR Sequences, Mahowald determined that these amino acid substitutions in Act5C and Act42A did not occur in regions of the actin molecule where actin binding proteins interact. By using the Drosophila as an easily controlled genetic system, Mahowald and his team discovered that mutations in the Act5C gene caused organism death, indicating that Act5C did have an important and isolated function. However, a hybrid gene containing Act42A prevented organism death, indicating that the amino acid differences between the two isoforms are not significant. Despite all of this, Mahowald concluded that tissues rich in Act5C gene expression cannot adequately function with only the Act42A isoform. In other words, while very similar in genetic sequencing, the various isoforms of actin are important to the survivability and functionality of the Drosophila.
References
Living people
1932 births
Cell biologists
Molecular geneticists
Biologists from Minnesota
People from Albany, Minnesota
Spring Hill College alumni
Johns Hopkins University alumni
Marquette University faculty
Indiana University faculty
Case Western Reserve University faculty
University of Chicago faculty
Drosophila melanogaster genetics | Anthony Mahowald | [
"Biology"
] | 1,386 | [
"Molecular geneticists",
"Molecular genetics"
] |
71,674,924 | https://en.wikipedia.org/wiki/Albert%20M.%20Gessler | Albert M. Gessler (191918 May 2003) was an ExxonMobil research chemist known for the development of elastomeric thermoplastics.
Personal
Gessler was a resident of Cranford, New Jersey for 58 years. He was active in civic life, founding Cranford's recycling program in 1971. He worked to establish Cranford's Conservation Center, chairing the Environmental Commission for several years. Gessler served as a leader in the Boy Scouts for more than 20 years. He received the Silver Beaver award in 1962. In 1999, the mayor of Cranford recognized Gessler's positive community impact with a resolution of Grateful Appreciation.
Education
Gessler completed his Bachelor of Arts in chemistry at Cornell University in 1941.
Career
Gessler began his career at Esso, joining in 1942. His most cited work is a 1959 patent on regarding a process for preparing a vulcanized blend of crystalline polypropylene and chlorinated butyl rubber. He was a mentor to Edward Kresge and coworker of William J. Sparks. He studied the chemical interaction between carbon black and various polymers. He served as chairman of the New York Rubber group in 1966. He was an organizer of the 1971 Gordon Conference on Elastomers. He is credited among the chief organizers of the popular text Science and Technology of Rubber. He was the 1986 recipient of the Melvin Mooney Distinguished Technology Award. At his retirement with 38 years of service, his title was senior research chemist.
References
1919 births
2003 deaths
Polymer scientists and engineers
20th-century American engineers
People from Cranford, New Jersey
Cornell University alumni
ExxonMobil people | Albert M. Gessler | [
"Chemistry",
"Materials_science"
] | 339 | [
"Polymer scientists and engineers",
"Physical chemists",
"Polymer chemistry"
] |
71,675,950 | https://en.wikipedia.org/wiki/Orthogonality%20%28mathematics%29 | In mathematics, orthogonality is the generalization of the geometric notion of perpendicularity to the linear algebra of bilinear forms.
Two elements and of a vector space with bilinear form are orthogonal when . Depending on the bilinear form, the vector space may contain null vectors, non-zero self-orthogonal vectors, in which case perpendicularity is replaced with hyperbolic orthogonality.
In the case of function spaces, families of functions are used to form an orthogonal basis, such as in the contexts of orthogonal polynomials, orthogonal functions, and combinatorics.
Definitions
In geometry, two Euclidean vectors are orthogonal if they are perpendicular, i.e. they form a right angle.
Two vectors and in an inner product space are orthogonal if their inner product is zero. This relationship is denoted .
A set of vectors in an inner product space is called pairwise orthogonal if each pairing of them is orthogonal. Such a set is called an orthogonal set (or orthogonal system). If the vectors are normalized, they form an orthonormal system.
An orthogonal matrix is a matrix whose column vectors are orthonormal to each other.
An orthonormal basis is a basis whose vectors are both orthogonal and normalized (they are unit vectors).
A conformal linear transformation preserves angles and distance ratios, meaning that transforming orthogonal vectors by the same conformal linear transformation will keep those vectors orthogonal.
Two vector subspaces and of an inner product space are called orthogonal subspaces if each vector in is orthogonal to each vector in . The largest subspace of that is orthogonal to a given subspace is its orthogonal complement.
Given a module and its dual , an element of and an element of are orthogonal if their natural pairing is zero, i.e. . Two sets and are orthogonal if each element of is orthogonal to each element of .
A term rewriting system is said to be orthogonal if it is left-linear and is non-ambiguous. Orthogonal term rewriting systems are confluent.
In certain cases, the word normal is used to mean orthogonal, particularly in the geometric sense as in the normal to a surface. For example, the y-axis is normal to the curve at the origin. However, normal may also refer to the magnitude of a vector. In particular, a set is called orthonormal (orthogonal plus normal) if it is an orthogonal set of unit vectors. As a result, use of the term normal to mean "orthogonal" is often avoided. The word "normal" also has a different meaning in probability and statistics.
A vector space with a bilinear form generalizes the case of an inner product. When the bilinear form applied to two vectors results in zero, then they are orthogonal. The case of a pseudo-Euclidean plane uses the term hyperbolic orthogonality. In the diagram, axes x′ and t′ are hyperbolic-orthogonal for any given .
Euclidean vector spaces
In Euclidean space, two vectors are orthogonal if and only if their dot product is zero, i.e. they make an angle of 90° ( radians), or one of the vectors is zero. Hence orthogonality of vectors is an extension of the concept of perpendicular vectors to spaces of any dimension.
The orthogonal complement of a subspace is the space of all vectors that are orthogonal to every vector in the subspace. In a three-dimensional Euclidean vector space, the orthogonal complement of a line through the origin is the plane through the origin perpendicular to it, and vice versa.
Note that the geometric concept of two planes being perpendicular does not correspond to the orthogonal complement, since in three dimensions a pair of vectors, one from each of a pair of perpendicular planes, might meet at any angle.
In four-dimensional Euclidean space, the orthogonal complement of a line is a hyperplane and vice versa, and that of a plane is a plane.
Orthogonal functions
By using integral calculus, it is common to use the following to define the inner product of two functions and with respect to a nonnegative weight function over an interval :
In simple cases, .
We say that functions and are orthogonal if their inner product (equivalently, the value of this integral) is zero:
Orthogonality of two functions with respect to one inner product does not imply orthogonality with respect to another inner product.
We write the norm with respect to this inner product as
The members of a set of functions are orthogonal with respect to on the interval if
The members of such a set of functions are orthonormal with respect to on the interval if
where
is the Kronecker delta.
In other words, every pair of them (excluding pairing of a function with itself) is orthogonal, and the norm of each is 1. See in particular the orthogonal polynomials.
Examples
The vectors are orthogonal to each other, since and .
The vectors and are orthogonal to each other. The dot product of these vectors is zero. We can then make the generalization to consider the vectors in : for some positive integer , and for , these vectors are orthogonal, for example , , are orthogonal.
The functions and are orthogonal with respect to a unit weight function on the interval from −1 to 1:
The functions are orthogonal with respect to Riemann integration on the intervals , or any other closed interval of length . This fact is a central one in Fourier series.
Orthogonal polynomials
Various polynomial sequences named for mathematicians of the past are sequences of orthogonal polynomials. In particular:
The Hermite polynomials are orthogonal with respect to the Gaussian distribution with zero mean value.
The Legendre polynomials are orthogonal with respect to the uniform distribution on the interval .
The Laguerre polynomials are orthogonal with respect to the exponential distribution. Somewhat more general Laguerre polynomial sequences are orthogonal with respect to gamma distributions.
The Chebyshev polynomials of the first kind are orthogonal with respect to the measure
The Chebyshev polynomials of the second kind are orthogonal with respect to the Wigner semicircle distribution.
Combinatorics
In combinatorics, two Latin squares are said to be orthogonal if their superimposition yields all possible combinations of entries.
Completely orthogonal
Two flat planes and of a Euclidean four-dimensional space are called completely orthogonal if and only if every line in is orthogonal to every line in . In that case the planes and intersect at a single point , so that if a line in intersects with a line in , they intersect at . and are perpendicular and Clifford parallel.
In 4 dimensional space we can construct 4 perpendicular axes and 6 perpendicular planes through a point. Without loss of generality, we may take these to be the axes and orthogonal central planes of a Cartesian coordinate system. In 4 dimensions we have the same 3 orthogonal planes that we have in 3 dimensions, and also 3 others . Each of the 6 orthogonal planes shares an axis with 4 of the others, and is completely orthogonal to just one of the others: the only one with which it does not share an axis. Thus there are 3 pairs of completely orthogonal planes: and intersect only at the origin; and intersect only at the origin; and intersect only at the origin.
More generally, two flat subspaces and of dimensions and of a Euclidean space of at least dimensions are called completely orthogonal if every line in is orthogonal to every line in . If then and intersect at a single point . If then and may or may not intersect. If then a line in and a line in may or may not intersect; if they intersect then they intersect at .
See also
Imaginary number
Orthogonal complement
Orthogonal group
Orthogonal matrix
Orthogonal polynomials
Orthogonal trajectory
Orthogonalization
Gram–Schmidt process
Orthonormal basis
Orthonormality
Pan-orthogonality occurs in coquaternions
Up tack
References
Abstract algebra
Linear algebra
Orthogonality | Orthogonality (mathematics) | [
"Mathematics"
] | 1,567 | [
"Linear algebra",
"Abstract algebra",
"Algebra"
] |
71,676,295 | https://en.wikipedia.org/wiki/Ta%C3%ADno%20creation%20myths | Taíno creation myths are symbolic narratives about the origins of life, the Earth, and the universe, intrinsically shaped from the nature of the tropical islands the Taíno inhabited. The Taíno people were the predominant indigenous people of the Caribbean and were the ones who encountered the explorer Christopher Columbus and his men in 1492. They flourished across much of the Caribbean for nearly 1,000 years before the arrival of Europeans and were one of the region’s most developed cultures.
The creation myths of the Taínos share similarities with other Native American cosmologies. The belief that in ancient mythical times, floods and civilizing heroes befell the world constitutes one of the most widespread concepts in Native American mythology, including in indigenous Taíno myths. Their creation myths are presented in terms of narratives where the events and the actors belong to a remote, primordial cosmos. A common feature of these myths is the expression of social laws that formulate proper and improper behavior; either characters behave in an opposite way from what is expected of an ordinary Taíno, or their behavior establishes proper Taínan behavior to be followed, and often a myth will exhibit an interplay of both kinds of behavior.
Sources
Modern knowledge of Taíno creation myths comes from 16th century Spanish chroniclers investigating the indigenous Caribbean culture. Columbus was very much interested in knowing about the religion of the Taínos; In his original letter to the Queen, he expressed the opinion that the natives had no religion whatsoever, however this was an attempt to persuade Isabella that it would be easy to convert them to Christianity. Nevertheless, he ordered the Hieronymite Friar who accompanied him on his second voyage, to study the religion of the natives of northern Hispaniola; the friar, later acquiring the native language, produced the volume titled as Legends and Beliefs of the Indians of the Antilles. In this work, Ramon Pane recorded not only the Taínos’ religious beliefs but also some of their myths. Because these narratives have an artistic, literary quality, Pane’s work is also considered the beginning of literature in the Americas. Unfortunately, the original Spanish manuscript has been lost, with only the Italian version including its many errors of transliteration surviving to the present day.
Another significant primary source comes from Father Bartolome de Las Casas, who wrote many books about the Taíno, including Historia de las Indias; although it was never finished, it has proved a rich source with a great deal of information about the customs of the natives. Las Casas came to the island in 1502, first as a colonizer using Taíno labor and treating them the same as other Spanish colonizers; however, soon he came to hate how badly these native people were mistreated, and decided to dedicate his life to improving their condition. In his writings he described how many of the cultural practices that Europeans considered objectionable in the Taíno had also been common among the Europeans’ own ancestors; using examples from Greek and Roman mythology, he tried to demonstrate that the thinking of the Taíno were not so different from that of Europe’s early pagans.
Although not all of Taíno myths have been preserved in the Spanish accounts, themes pertaining to their mythology are also symbolically encoded in their ritual material culture, objects such as sculptures, rattle gourds, and petroglyphs; it has been therefore possible for anthropologists to reconstruct some of the lost elements of these myths. For example, modern investigators have compared Pane's descriptions of Taíno art with archeological discoveries and the myths and vocabulary of other present-day Arawak groups. Thanks to these works, such as the research of José Juan Arrom, it has been possible to interpret the most important myths and Antillean divinities.
The Origin of the Sun and the Moon
The cave of Iguanaboina was the primordial den from which the Sun emerges to illuminate the earth and to which it returns to hide as the moon emerges. In the book “An Account of the Antiquities of the Indians,” Arrom provides his account of Friar Ramon Pané’s discussion of Boinayel:
“They also say that the Sun and the Moon emerged from a cave called Iguanaboina, located in the country of a cacique [chief] named Mautiatihuel, and they hold it in great esteem and have it painted in their fashion, without any figures, with a lot of foliage and other such things. And in the said cave there were two zemis [cemis] made from stone, small ones, the size of half an arm, with their hands tied, and they seemed to be sweating. The Taíno valued those zemis very highly; and when it did not rain, they say that they would go in there to visit them, and it would rain at once. And one zemi they called Boinayel and the other Márohu”.
The Origins of Life and the Ocean, or Bagua
The birth of the ocean and the life within it is the first act of creation of the Taíno universe. The tale is told in two different but closely related myths from Hispaniola. The same myths have also been artistically encoded in a sequence of petroglyphs located in the central precinct of the famous ceremonial center of Caguana in Puerto Rico. The first myth speaks of the powerful creator god called Yaya, considered the supreme being of the universe. Considered the life-giving spirit and causal force of creation that presides over the universe, Yaya plays multiple functions in the mythology, as supreme being, cacique, and father. The myth recounts how Yaya's son Yayael was ostracized for wanting to kill his father and consequently banished; afterwards, upon Yayael’s return, his father killed him and placed his bones inside a gourd to hang from the roof of the house, where it remained for a time. One day wishing to see his son, Yaya requested his wife to take down the gourd and empty it to see the bones of his son. From the gourd, many large and small fish gushed out. Seeing that the bones were transformed into fish, they resolved to eat them.
Along with expressing social norms, this first myth also establishes funerary rites and the cult of the dead. Supported by the descriptions provided by Columbus himself during his visit of eastern Cuba, it was a Taíno custom of burning the deceased and selecting the skull and long bones to “bury” them inside a gourd or woven basket that is to be hung from the roof of the house. As many other Amerindians, the Taíno considered bones not simply as symbols for the dead, death, sterility, quite the contrary, they were the source of life itself, and as the myth recounts, Yayael’s dead bones had the power to create ordered life in the primordial world
The second myth recounts the story of the mischievous sons of Itiba Cahubaba, the ‘Great Bleeding Mother’ who died giving birth to her four sons. The first son, named Deminan Caracaracol led his unnamed brothers in misadventures of creation throughout the Caribbean primordial world. These mythic tricksters are known as civilizing heroes in the Taíno mythology. The myth begins with the hungry brothers entering Yaya's house to steal food; after they lowered the gourd where Yayael’s bones were placed and began eating fish, they heard Yaya returning, and while trying to hang the gourd back on the roof in haste, they dropped it and it broke. It is said that so much water came out of the gourd that it covered the earth and with it many fish poured out; and this is the oceans's origins.
The Quadruplets
Similar to Yayaels case, after stealing and breaking the gourd, the punishment was banishment from Yaya’s chiefdom/land. The brothers were condemned to live away from the domain presided by the supreme being. Unlike Yayael, who returns home in defiance of Yaya, the four brothers never tried to return. Because of their compliance with the norm of banishment, the acquisition of culture was possible. It was the banishment that caused these culture heroes to begin the long journey that leads to the discovery of the secrets of culture for the benefit of humankind, such as agriculture, fire, and entheogenic plants.
Taíno myths recount that it was first Deminan and his brothers who learned about fire for cooking, and how to plant and harvest in order to make their staple casabe bread. They were the ones who wrestled from the proverbial mythical wise old man Baymanaco, the rituals and secrets of shamanism, healing, and magic, such as the use of tobacco, digo, and cohoba. Robbing Bayamanaco established the casabe as a basic food in their diet; established the use of fire, which gives heat and light, and allows cooking; and established the knowledge of cohoba, a hallucinogenic plant that makes communication with the gods possible. The centerpiece of the religious ceremony crucial to the Taíno, cohoba is a plant (Anadenanthera peregrina) whose seeds, when crushed and mixed with an alkaline substance (like lime or ground burned shells), produce a powder that can be sniffed to induce hallucinogenic experiences—the effects of which have been discussed in depth by Gerardo Reichel-Dolmatoff (1971, 1975). It was therefore regarded by the Taíno as a sacred substance that permitted the ordinary person to transcend into the extraordinary world of the supernatural. The inhalation of powders from this plant was the most important religious and political ritual.
References
Creation myths
Taíno mythology
Taíno
Caribbean mythology | Taíno creation myths | [
"Astronomy"
] | 2,023 | [
"Cosmogony",
"Creation myths"
] |
71,678,368 | https://en.wikipedia.org/wiki/Beijerinck%20Virology%20Prize | The M.W. Beijerinck Virology Prize (M.W. Beijerinck Virologie Prijs) is a prize in virology awarded every two years by the Koninklijke Nederlandse Akademie van Wetenschappen (KNAW). The prize consists of a medal and a monetary award of €35,000. KNAW's two conditions for the prize nomination are that the nominee must be an internationally recognized researcher who has "made a groundbreaking contribution to research in the field of virology in the broadest sense" and must have an appointment at a university or research institute.
The prize is named in honor of the Dutch microbiologist Martinus Willem Beijerinck. KNAW appoints an advisory committee which gives advice to KNAW concerning the prize nominees. KNAW has regulations for who may submit nominations. Before 2014 the prize was awarded every three years.
Prize winners
1966 Egbertus van Slogteren, Netherlands
1969 , United States
1972 W. Berends, Netherlands
1975 E.M.J. Jaspars and A. van Kammen, Netherlands
1978 Lex van der Eb, Netherlands
1983 B.A.M. van der Zeijst, Netherlands
1986 Walter Fiers, Belgium
1989 , Netherlands
1992 H. zur Hausen, Germany
1996 , Netherlands/Germany
1998 A.D.M.E. Osterhaus, Netherlands
2001 R.A. Weiss, United Kingdom
2004 D.C. Baulcombe, United Kingdom
2007 Charles M. Rice, United States
2010 Eckard Wimmer, United States
2013 Félix Augusto Rey, France
2015 Peter Palese, United States
2017 Raul Andino, United States
2019 Eva Harris, United States
2021 Ralf Bartenschlager, Germany
References
Awards established in 1966
Dutch honorary society awards
Awards of the Royal Netherlands Academy of Arts and Sciences
1966 establishments in the Netherlands | Beijerinck Virology Prize | [
"Technology"
] | 395 | [
"Science and technology awards",
"Science award stubs"
] |
71,679,866 | https://en.wikipedia.org/wiki/Markham%20Moor%20Scorer%20Building | The building designed by Sam Scorer at the Markham Moor services (sometimes known as the Markham Moor Petrol Station, Markham Moor Hypar or Markham Moor Papilo) is a Grade II listed building originally designed as a petrol station. It is beside the A1 south-bound at the Markham Moor junction services and was built between 1959 and 1960 with the aid of engineer Kalman Hajnal-Kónyi. It is currently a Starbucks.
Design
Designed by Lincoln-based architect Sam Scorer, the original structure consisted only of hyperbolic paraboloid - to serve as a petrol station: the building underneath was a later addition. The petrol station was one of a series of buildings designed by Scorer which included hyperbolic structures. These structures (sometimes known as 'hypars') were experimental structures with the intention of making them appear to hover and also in this case a show of engineering efficiency, since the concrete roof structure is only 75mm thick.
The cantilever canopy is constructed using a shell concrete structure which forms a continuous plane developed from two parabolas inverted relative to each other at right angles. The canopy thus acts as two systems of arches with one set of arches under compression and the other under tension.
History
Ownership
Petrol station
The building was designed and built as a petrol station; it was operated by National Benzole from 1960 until it was taken over by Little Chef in 1989. While the canopy was designed as an architectural curiosity, it was also designed to catch the eye of a motorist, giving them plenty of time to pull into the petrol station.
Little Chef
In 1989 the structure was converted to a Little Chef restaurant, and the building beneath the canopy was built. In 2003 the Highways Agency proposed plans for a flyover which would involve the demolition of the Little Chef, however the plans were later revised. The Little Chef on this site closed in 2012.
Interim years
The building was disused between 2012 and 2019. On 27 March 2012, shortly after the Little Chef restaurant closed, Historic England awarded Grade II listed building status to the canopy to the former petrol station and its structural supports.
Starbucks
In 2019 the site was taken over by Starbucks. The building and roof were renovated and converted into a drive-through.
Threat of demolition
In 2003 the Highways Agency proposed a junction improvement which involved the construction of a flyover necessitating the demolition of the building. However, after many objections from the residents of nearby Elkesley and those interested in the welfare of the building, the plans were revised, including improved access to the site.
See also
Listed buildings in West Drayton, Nottinghamshire
References
External links
Images of the original petrol station:
https://englishbuildings.blogspot.com/2020/06/markham-moor-nottinghamshire.html
https://flickr.com/photos/nedtrifle/3657463823
Historic filling stations in the United Kingdom
A1 road (Great Britain)
Bassetlaw District
Hyperboloid structures | Markham Moor Scorer Building | [
"Technology"
] | 597 | [
"Structural system",
"Hyperboloid structures"
] |
71,681,687 | https://en.wikipedia.org/wiki/Carotegrast%20methyl | Carotegrast methyl (trade name Carogra) is a drug used for the treatment of ulcerative colitis.
Carotegrast methyl is a prodrug that has little pharmacological activity itself. The methyl ester, which is designed to enhance oral bioavailability, is hydrolyzed to a carboxylic acid, carotegrast, by the enzyme carboxylesterase 1 in the liver. Carotegrast is an α4-integrin antagonist which prevents the chronic inflammation affecting the gastrointestinal tract in individuals with ulcerative colitis.
Carotegrast methyl received approval in Japan in March 2022 for the treatment of moderate ulcerative colitis in patients who had inadequate response to mesalazine.
References
Prodrugs
Methyl esters
Chlorobenzene derivatives
Benzamides
Dimethylamino compounds
Quinazolinones | Carotegrast methyl | [
"Chemistry"
] | 189 | [
"Chemicals in medicine",
"Prodrugs"
] |
71,682,162 | https://en.wikipedia.org/wiki/Katharina%20Lodders | Katharina Lodders is a German-American planetary scientist and cosmochemist who works as a research professor in the Department of Earth and Planetary Sciences at Washington University in St. Louis, where she co-directs the Planetary Chemistry Laboratory. Her research concerns the chemical composition of solar and stellar environments, including the atmospheres of planets, exoplanets, and brown dwarfs, and the study of the temperatures at which elements condense in stellar environments.
Education and career
Lodders completed her doctorate in 1991 at the University of Mainz, with research on the cosmochemistry of trace elements performed at the Max Planck Institute for Chemistry. She joined Washington University in St. Louis as a postdoctoral researcher in 1992 before continuing there as a research professor.
She served as a program director for galactic astronomy at the National Science Foundation from 2010 to 2013.
Books
Lodders is the coauthor of books including:
The Planetary Scientist's Companion (with Bruce Fegley, Jr., Oxford University Press, 1998)
Chemistry of the Solar System (with Bruce Fegley, Jr., Royal Society of Chemistry, 2010)
Recognition
Lodders won the 2021 Leonard Medal of The Meteoritical Society, its highest award, "for her work on the condensation of presolar grains in stellar atmospheres and her compilation of the Solar System Abundances of the Elements and the condensation temperatures of the elements".
References
External links
Year of birth missing (living people)
Living people
Planetary scientists
Women planetary scientists
Astrochemists
German chemists
German women chemists
American chemists
American women chemists
Johannes Gutenberg University Mainz alumni
Washington University in St. Louis faculty | Katharina Lodders | [
"Chemistry"
] | 335 | [
"Astrochemists"
] |
71,684,705 | https://en.wikipedia.org/wiki/Big%20Stan%20%28drill%20rig%29 | Big Stan is a vehicle-mounted drill rig built in 1986 by Anderson Drilling. The rig has been used on a number of construction projects in which conventional, smaller drilling rigs were unable to be used, particularly when projects call for drilling into hard soil. Notably, Big Stan was used in the construction of the First National Bank Tower in Omaha, the Benicia-Martinez bridge near San Francisco, and on expansions to the I-15/215 Beltway in Las Vegas. The drill rig was featured on Discovery Channel's show “Monster Machines” in 2007.
Big Stan features a two-piece design, significantly lowering the time and manpower needed to assemble it compared to contemporary rigs. Big Stan employs a screw conveyor capable of exerting of torque and of downward force to a maximum depth of . Its drill bit is capable of moving of soil per rotation and its drill bucket is able to move up to of soil per rotation. The rig has been estimated as one of, if not the largest, vehicle-mounted drilling rigs in the world.
History
Big Stan was built in 1986 by Anderson Drilling (Now part of Keller Group PLC) in Lakeside, California. The machine cost $1.5 million to construct and was named after the company president at the time, Stan Anderson, who was given a similar nickname due to his height of 6 ft 3 in (1.91 m). The rig was originally built to meet the demand for a more powerful mobile drilling rig, specifically a demand for rigs capable of boring up to deep. At the time, Big Stan was claimed to be the largest portable drill rig in the United States, with some estimates placing it as the largest vehicle-mounted drill rig in the world.
From May to June 1999, Big Stan was used to drill the caissons for the First National Bank Tower in Omaha, Nebraska. In 2004, while working on an expansion to the Benicia-Martinez bridge near San Francisco, Big Stan was filmed by Discovery Channel's Canadian outlet for the show “Monster Machines”. The episode aired in 2007. In June 2007, Big Stan was used in the construction of the Pacific Street Bridge, in Oceanside, California. Big Stan was selected for its ability to achieve depths of ; conventional rigs were not capable of tunneling deep enough into the soft riverbed soil to earthquake proof the structure. That same year, Big Stan was used for construction work on the Upper Northwest Interceptor sewage system. This project involved Big Stan drilling 41 vertical shafts, to in diameter, and to in depth. These tunnels were later finished by Vadnais Corp. who horizontally connected the segments by micro-tunneling. In January 2009, Big Stan was taken to La Plata County, Colorado to drill at the Ridges Basin Dam. Here, it bored a -deep, diameter shaft as part of a larger project to build irrigation infrastructure to the surrounding homes. That same year, Big Stan was taken to Snyder, Texas to work on the Snyder Wind Energy Project. Here, it was used to drill deep caissons into hard clay and sandstone.
In August 2011, the drill rig was moved to Nevada to work on expansions to Interstate 15 in Las Vegas. The drill was contracted due to the lack of machines capable of breaking up the caliche-laden sedimentary rock present in the region. In addition, it was also used in the construction of the Blue Diamond Road flyover. Later that month, Big Stan was used to drill the foundation for the Gold Line basket bridge in Los Angeles, California. In 2015, Big Stan was used in the construction of the Yucca Loma Bridge in Apple Valley, California.
Design
Big Stan was designed as a vehicle mounted drill rig that is normally mounted on a long, 5-axle truck, but is also compatible with a specially designed continuous track-style carrier. When made fully operational, the top of the drill (the boom arm) can extend to in height when leveled with the ground. The truck Big Stan is normally mounted to is equipped with 5 hydraulic jacks designed to lift, tilt, and lower the drill. These jacks provide the drill with of lifting force and 360 degrees of rotation. These hydraulic jacks can also be used for rig assembly and breakdown. Big Stan can uniquely be split into two pieces which can be transported independently. When split apart, the engine and upper tower are carried by a 7-axle tractor-trailer, while the lower tower and rest of the drill are carried by a 5-axle tractor-trailer. This is in contrast to other contemporary drill rigs, which required being dismantled into 8 to 10 pieces for transport. This design, along with the vehicle mount's built-in hydraulic jacks, allow a team of two people to assemble the rig in 30 minutes, compared to other contemporary rigs that required upwards of a week to properly set up.
Big Stan weighs 125 tons (113.4 metric tons), and is capable of exerting of torque and of downward force (crowd pressure). Big Stan features a screw conveyor, or auger, as its primary means of excavating soil. The drill is capable of boring down at up to 39 rpm and its auger weighs . The drill can accommodate a drill bit that is up to in diameter and move dirt at a rate of up to per rotation, depending on diameter, or drill buckets with capacities up to . The rotary table has a diameter, double-pinion ring gear driven by a six-speed transmission built by Allison transmission, through a drivetrain with two drivebelts made by Clark. Big Stan is powered by a , six-cylinder diesel engine made by Cummins.
See also
Tunnel boring machine
Trenchless technology
Boring (manufacturing)
References
Drilling rigs
Construction | Big Stan (drill rig) | [
"Engineering"
] | 1,166 | [
"Construction"
] |
71,690,154 | https://en.wikipedia.org/wiki/ACM%20Conference%20on%20Hypertext%20and%20Social%20Media | The ACM Conference on Hypertext and Social Media (Hypertext) is one of the oldest international conference series on the crossroads of Human-Computer Interaction and Information Science. The full list of conferences in the series can be found on the Association for Computing Machinery Hypertext Web page, and papers are available through the ACM Digital Library.
History
The modern ACM Hypertext conference has its roots in the US-based Hypertext (HT) conference (1987, 1989) and European Conference on Hypertext (ECHT) (1990), coming together in 1991 under the organisation of Association for Computing Machinery Special Interest Group SIGLINK (renamed ACM SIGWEB in 1998) with the name ACM Hypertext and Hypermedia.
The conference has been notable for being open to literary authors and scholars in addition to computer scientists. This made it an important space for the development of early hypertext fiction and digital poetry. At the first Hypertext conference, in 1987, both the hypertext authoring system Storyspace and one of the first works of hypertext fiction, Afternoon, a story, were presented in public for the first time. In the 1990s, Deena Larsen and other authors of electronic literature hosted pre-conference Hypertext Writers' Workshops that were important community-building events.
The scope of the conference has been gradually expanded to include the World Wide Web and other types of information-linking systems, and in 2012 the conference changed its name to reflect this widened scope to become the ACM Conference on Hypertext and Social Media.
Awards
The ACM Conference on Hypertext and Social Media has two named best paper awards that are given out annually: the Douglas Engelbart Best Paper Award and the Ted Nelson Newcomer Award.
References
Association for Computing Machinery conferences
Computer science conferences
Computer conferences
Electronic literature | ACM Conference on Hypertext and Social Media | [
"Technology"
] | 364 | [
"Computer science",
"Computer science conferences"
] |
71,692,105 | https://en.wikipedia.org/wiki/Entoto%20Observatory%20Space%20Science%20Research%20Center | The Entoto Observatory Space Science Research Center (EORC) is an astronomical observatory station located in Mount Entoto, close to Addis Ababa, Ethiopia. The centre was initiated during the establishment of the Ethiopian Space Science Society (ESSS) and officially began operations in 2012. The Board of Directors appointed Dr. Solomon Belay Tessema as the first Scientific Director in May 2012. The Ethiopian space program was born from EORC, and the strong leadership and commitment of Dr. Solomon Belay Tessema were the reasons for its creation. He has established graduate programs in four areas astronomy and astrophysics, space science, Remote sensing and Geodesy affiliated with AAU with a limited budget and resources. Dr. Solomon is the father of the space program in Ethiopia in particular East African in general.
The Entoto Observatory installed twin 1m telescopes in early 2014, and science operations began in early 2015. Final commissioning was completed by early 2015 after the installation of essential supplemental equipment. Currently, it is financed by a consortium of universities, ESSS, and the Ethiopian government. It plans to expand the center in Lalibela and other towns.
History
The Entoto Observatory and Space Science Research Center (EORC) was initiated during the establishment of the Ethiopian Space Science Society (ESSS) in 2004. The first initiative was conducted by the board members of ESSS and established the Astronomy and Space Science Research center at Entoto and the Ethiopian Highlands. In 2011, the owner was asked by ESSS to develop a draft list of science initiatives to support the establishment of the center. The center was established in 2012, supported by numerous private and public universities around the world.
In 2013, the two domes for the twin telescopes were completed by deserting the trees. The Entoto Observatory has twin 1m telescope installed in early 2014, and science operations began in early 2015. Final commissioning was completed by early 2015 after installment of internet connections, scientific equipment, lighting systems, and testing equipment. Currently it is financed by a consortium of universities, ESSS and the Ethiopian government.
Future benefit
The Entoto Observatory offers benefits to Ethiopian astronomers and those in the East African region. It also intended to boost research programs and a student training center. The initiative also selected a potentially ideal place such as Lalibela for a research center. Two sites have been set up with the requisite equipment (DIMMs, automatic weather stations, all sky cameras, sky brightness monitors), and infrastructure support (roads, housing) has been established.
References
Science and technology in Ethiopia
Astronomical observatories
2012 establishments in Ethiopia | Entoto Observatory Space Science Research Center | [
"Astronomy"
] | 531 | [
"Astronomical observatories",
"Astronomy organizations"
] |
71,693,313 | https://en.wikipedia.org/wiki/HD%2037289 | HD 37289, also known as HR 1916, is a solitary, orange hued star located in the northern circumpolar constellation Camelopardalis. It has an apparent magnitude of 5.61, making it faintly visible to the naked eye under ideal conditions. Based on parallax measurements from the Gaia spacecraft, the object is estimated to be 308 light years distant. It appears to be approaching the Sun, having a heliocentric radial velocity of .
HD 37289 has a stellar classification of K5 III, indicating that it is an evolved red giant. Gaia DR3 stellar evolution models place it on the red giant branch. This means that it is currently fusing a hydrogen shell around an inert helium core. At present it has 3.3 times the mass of the Sun and at the age of 293 million years, it has expanded to a radius of . It radiates at 70 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of . HD 37289 has been calculated to have a metallicity approximately around solar level.
References
Camelopardalis
K-type giants
037289
026882
1916
BD+65 00485 | HD 37289 | [
"Astronomy"
] | 251 | [
"Camelopardalis",
"Constellations"
] |
71,693,639 | https://en.wikipedia.org/wiki/72%20Tauri | 72 Tauri (abbreviated 72 Tau) is a possible binary star in the zodiac constellation of Taurus. It is faintly visible to the naked eye with an apparent visual magnitude of +5.5, although only 0.29° from the brighter υ Tauri. Based upon an annual parallax shift of seen from Earth, it is around 410 light years from the Sun.
Properties
72 Tauri is a B-type main sequence star with a stellar classification of B7V. With a mass of and an estimated age of 38 million years, it is 2.8 times the size of the Sun and 185 times its luminosity.
Occasionally this star system is given the Bayer designation υ2 Tauri with υ Tauri, which is separated from it by 0.29° in the sky. υ Tauri is a foreground star, the two are unrelated, and although 72 Tauri lies near the Hyades open cluster, it is much further away.
72 Tauri lies near the ecliptic and can be occulted by the moon. Observations of an occultation in 1985 showed that it was a binary star with the two components separated by . There has been no confirmation of this finding and other sources list the star as single.
References
B-type main-sequence stars
Tauri, Upsilon
Taurus (constellation)
Durchmusterung objects
Tauri, 072
020789
028149
1399 | 72 Tauri | [
"Astronomy"
] | 294 | [
"Taurus (constellation)",
"Constellations"
] |
71,694,509 | https://en.wikipedia.org/wiki/Engyodontium%20aranearum | Engyodontium aranearum is a species of ascomycete fungus in the family Cordycipitaceae. It parasitizes the long bodied cellar spider (Pholcus phalangioides). It causes 100% mortality in infected spiders.
References
Fungi described in 1984
Cordycipitaceae
Fungus species | Engyodontium aranearum | [
"Biology"
] | 68 | [
"Fungus stubs",
"Fungi",
"Fungus species"
] |
71,695,301 | https://en.wikipedia.org/wiki/Arachnomyces%20bostrychodes | Arachnomyces bostrychodes is a species of infectious ascomycete fungus discovered in 2021 from clinical specimens of fungal strains in Texas, United States.
Etymology
The specific epithet comes from the Greek βοστρυχος-, meaning curl, referencing the curly appearance of the reproductive hyphae.
Morphology and asexual reproduction
A. bostrychodes grows septate, hyaline, branched, vegetative hyphae with smooth and thin walls, between 1 and 2 μm wide. The fertile hyphae are well-differentiated, arising as lateral branches from the vegetative hyphae, successively branching to form dense, tightly curled, sinuous clusters that are also between 1 and 2 μm wide, forming random arthroconidia both intercalary and terminally.
The conidia measure 4–8 x 1–2 μm, are mostly curved and truncated at one or more commonly both ends; they are enteroarthric, hyaline, one-celled, smooth-walled, cylindrical, barrel-shaped; they are finger-shaped when terminal. The conidia are separated from the fertile hyphae by rhexolysis. There have been no observations of chlamydospores, racquet-shaped hyphae, setae, or sexual reproduction.
References
Fungi described in 2021
Eurotiomycetes
Fungus species | Arachnomyces bostrychodes | [
"Biology"
] | 293 | [
"Fungi",
"Fungus species"
] |
47,541,633 | https://en.wikipedia.org/wiki/Sigurd%20Angenent | Sigurd Bernardus Angenent (born 1960) is a Dutch-born mathematician and professor at the University of Wisconsin–Madison. Angenent works on partial differential equations and dynamical systems, with his recent research focusing on heat equation and diffusion equation. The Angenent torus and Angenent ovals are special solutions to the mean curvature flow published by Angenent in 1992; The Angenent torus remains self-similar as it collapses to a point under the flow, and the Angenent ovals are the only compact convex ancient solutions other than circles for the curve-shortening flow.
Angenent was raised in Haarlem, the Netherlands. He obtained his PhD in Mathematics from Leiden University in 1986. In 1996 Angenent became a correspondent of the Royal Netherlands Academy of Arts and Sciences.
At the University of Wisconsin–Madison, he is the director of the Undergraduate Mathematics Program. After becoming frustrated with textbooks' high prices and poor quality, he wrote and made available his own notes for all classes.
References
External links
Profile at the Mathematics Genealogy Project
Profile at University of Wisconsin–Madison
1960 births
Living people
20th-century Dutch mathematicians
21st-century Dutch mathematicians
Dynamical systems theorists
Dutch systems scientists
Leiden University alumni
Members of the Royal Netherlands Academy of Arts and Sciences
Scientists from Haarlem
University of Wisconsin–Madison faculty | Sigurd Angenent | [
"Mathematics"
] | 274 | [
"Dynamical systems theorists",
"Dynamical systems"
] |
47,542,146 | https://en.wikipedia.org/wiki/Scale%20of%20chords | A scale of chords may be used to set or read an angle in the absence of a protractor. To draw an angle, compasses describe an arc from origin with a radius taken from the 60 mark. The required angle is copied from the scale by the compasses, and an arc of this radius drawn from the sixty mark so it intersects the first arc. The line drawn from this point to the origin will be at the target angle.
Mathematics
A chord is a line drawn between two points on the circumference of a circle. Look at the centre point of this line. For a circle of radius , each half will be so the chord will be . The line of chords scale represents each of these values linearly on a scale running from 0 to 60.
Availability
It appears on Gunter's scale and the Foster Serle dialing scales. The commercial company Stanley marketed a metal version (Stanley 60R Line of Chords Rule) in 2015.
See also
Ptolemy's table of chords
References
Notes
Bibliography
Angle
Scientific instruments | Scale of chords | [
"Physics",
"Technology",
"Engineering"
] | 209 | [
"Geometric measurement",
"Scalar physical quantities",
"Physical quantities",
"Measuring instruments",
"Scientific instruments",
"Wikipedia categories named after physical quantities",
"Angle"
] |
47,543,584 | https://en.wikipedia.org/wiki/Etridiazole | Etridiazole is a fungicide and pesticide used for prevention of pythium ultimum on cotton plants.
Synthesis
Etridiazole can be synthesised from acetonitrile as follows:
It can also be is produced by the reaction of trichloroacetamidine hydrochloride with trichloromethanesulfenyl chloride, and then with sodium hydroxide in ethanol.
Reactivity
Etridiazole is stable under normal conditions, but degrades upon continuous exposure to sunlight, and is hydrolysed by alkalis. When heated to decomposition, it emits toxic fumes of hydrogen chloride, sulfur oxides, and nitrogen oxides.
Safety
Etridiazole has been classified as a Group B2 Probable Human Carcinogen.
References
Fungicides
Thiadiazoles
Trichloromethyl compounds
Ethoxy compounds | Etridiazole | [
"Biology"
] | 188 | [
"Fungicides",
"Biocides"
] |
47,546,141 | https://en.wikipedia.org/wiki/Suaeda%20pulvinata | Suaeda pulvinata is an endemic seepweed from Mexico. It lives in the shores of Lake Texcoco and Lake Totolcingo. It lives underwater as an aquatic plant for half of the year and on dry land as a terrestrial plant for the other half due to the changing levels of the lakes that it inhabits. It is a perennial flat herb with prostrate stems. Its leaves and inflorescences are green to reddish in color.
This species is important for people that live in the states of Puebla and Tlaxcala, as it is an edible vegetable. The dish that is prepared using this species is known as romeritos.
It has been found in molecular phylogenetic studies that this taxon is monophyletic. Due to differences in its phylogenetic position in its nuclear ITS tree and its chloroplast rpl32-trnL tree, it is thought this species is the result of hybridization of ancestral species of Suaeda.
The first scientific collector who found this plant was Efraim Hernández Xolocotzi. (Later, it was cited by Guadalupe Ramos in her university degree thesis.) However, he misidentified it for S. nigra. It was in 2013 that Ernesto Alvarado Reyes and Hilda Flores Olvera noticed it was a different species.
References
External links
http://www.tropicos.org/Name/100425076
pulvinata
Halophytes
Flora of Mexico
Edible plants
Barilla plants | Suaeda pulvinata | [
"Chemistry"
] | 311 | [
"Halophytes",
"Salts"
] |
47,546,346 | https://en.wikipedia.org/wiki/Leohumicola%20atra | Leohumicola atra is a species of fungus. It is named after the dark-brown colour of its terminal conidia cells ( is Latin for "dark"). It was found in Crater Lake National Park, Oregon, from heated soil. This species' conidia terminal cell becomes a darker brown compared to its cogenerate species, being nearly black.
Description
Its conidiogenous hyphae are hyaline, measuring approximately 1–2.5 μm wide, often found in fascicles in aerial mycelium. These are reduced to a single denticle that is 0.5–1.0 μm long and 1.0–2.0 μm wide. Conidia are two-celled, either solitary or distributed side by side in clusters. Its terminal cell is 4.5–5.5 by 4.0–5.5 μm, being globose to subglobose, transitioning to a dark brown colour; its conidial walls are slightly thick. Aleurioconidia are sometimes found as single-celled, with a terminal cell directly attached to the hypha, and with no basal cell. Chlamydospores are sparsely produced, being intercalary, single, and the same colour as the conidial terminal cell. The vegetative mycelium often carry swollen, monilioid hyphae that are 1.5 to 2 μm wide, septate, and show thickened walls.
References
Further reading
Chen, Juan, et al. "Leohumicola, a genus new to China." Mycotaxon 108.1 (2009): 337–340.
Shenoy, Belle Damodara. Multigene phylogeny of selected anamorphic ascomycetes. Diss. The University of Hong Kong (Pokfulam, Hong Kong), 2007.
Leotiomycetes
Fungal plant pathogens and diseases
Fungus species | Leohumicola atra | [
"Biology"
] | 406 | [
"Fungi",
"Fungus species"
] |
47,546,353 | https://en.wikipedia.org/wiki/Leohumicola%20incrustata | Leohumicola incrustata is a species of fungus. It was named after the appearance of its terminal conidial cells, incrusted with a crust-like slime. It was first found in the Cape of Good Hope Nature Reserve, from heated soil. Large warts or the production of slime on its terminal cell are this species' defining characteristics. Its conidia are similar to those of L. verrucosa, however in the latter the wall ornamentation forms smaller warts.
Description
Its conidiogenous hyphae are hyaline, measuring approximately 1.5–2.0 μm wide, often found in fascicles in aerial mycelium. These are reduced to a single denticle that is 1.0–3.0 μm long and 1.5–3.5μm wide. Conidia are two-celled, either solitary or distributed side by side in clusters. Its terminal cell is 4.0–5.5 by 4.0–5.0 μm, being globose to subglobose, transitioning to a pale brown to dark brown colour; its conidial walls are slightly thick, smooth or verrucose, with warts measuring 0.75 to 1.5 μm, incrusted with a brown-coloured slime that is 1–2 μm thick around the apex. Its basal cell measures 2.5–4.5 by 2.0–3.0 μm. Chlamydospores are sparsely produced, being intercalary, single, and the same colour as the conidial terminal cell. The vegetative mycelium often carry swollen, monilioid hyphae that are 1.5 to 3 μm wide, septate, and show thickened walls.
References
Further reading
Leotiomycetes
Fungal plant pathogens and diseases
Fungus species | Leohumicola incrustata | [
"Biology"
] | 396 | [
"Fungi",
"Fungus species"
] |
47,546,890 | https://en.wikipedia.org/wiki/Confiture | A confiture is any fruit jam, marmalade, paste, sweetmeat, or fruit stewed in thick syrup. Confit, the root of the word, comes from the French word confire, which literally means 'preserved'; a confit being any type of food that is cooked slowly over a long period of time as a method of preservation.
See also
Fruit preserves – fruits combined with sugar readied in a manner appropriate for long-term storage
Konfyt – South African jam
Spoon sweets – Fruits candied in a syrupy glaze, offered in Greece as a gesture of hospitality
Varenye – Russian preserves made with whole fruits or large fruit pieces
Slatko – a whole-fruit preserve in Eastern European cuisine
List of spreads
References
Condiments
Culinary terminology
Food ingredients
Food preservation
French cuisine
Spreads (food)
Preserved fruit | Confiture | [
"Technology"
] | 176 | [
"Food ingredients",
"Components"
] |
47,547,420 | https://en.wikipedia.org/wiki/Atul%20Kumar%20%28chemist%29 | Atul Kumar is a synthetic organic chemist, Professor & Chief Scientist at the Academy of Scientific and Innovative Research (AcSIR) and Chairperson of Medicinal and Process Chemistry Division Central Drug Research Institute (CSIR-CDRI) at Lucknow, India and a Dean at National Institute of Pharmaceutical Education and Research, Raebareli.
Academic work
Kumar has about 24 years experience in drug design, medicinal chemistry and Green Chemistry
Dr. Kumar's major contributions are the invention of anti-osteoporosis drug candidate CDRI-99/373 (CENTHANK), which is an currently in phase 1 clinical trial and NCE anti-cancer compound CDRI-S-007-1235, is currently in Pre-clinical stage.
References
External links
Official website at CDRI
Year of birth missing (living people)
Living people
Council of Scientific and Industrial Research
Indian organic chemists
20th-century Indian chemists | Atul Kumar (chemist) | [
"Chemistry"
] | 185 | [
"Organic chemists",
"Indian organic chemists"
] |
47,547,936 | https://en.wikipedia.org/wiki/NGC%206115 | NGC 6115 is an open cluster in the constellation Norma. It is located 2 degrees southeast of Gamma Normae. It is 3175 light-years distant and thought to be around 870 million years old.
References
NGC 6115
6115
Norma (constellation) | NGC 6115 | [
"Astronomy"
] | 53 | [
"Norma (constellation)",
"Constellations"
] |
47,547,979 | https://en.wikipedia.org/wiki/NGC%205999 | NGC 5999 is an open cluster in the constellation Norma. Its brightest star is HIP 78355. It is 5310 light-years distant and thought to be around 400 million years old.
References
NGC 5999
5999
Norma (constellation) | NGC 5999 | [
"Astronomy"
] | 54 | [
"Norma (constellation)",
"Constellations"
] |
47,548,229 | https://en.wikipedia.org/wiki/NGC%206005 | NGC 6005 is an open cluster in the constellation Norma. It is 5875 light-years distant and thought to be around 1.15 billion years old.
References
NGC 6005
6005
Norma (constellation) | NGC 6005 | [
"Astronomy"
] | 44 | [
"Norma (constellation)",
"Constellations"
] |
47,548,743 | https://en.wikipedia.org/wiki/NGC%205925 | NGC 5925 is an open cluster in the constellation Norma. It is 5070 light-years distant and thought to be around 316 million years old.
References
NGC 5925
5925
Norma (constellation) | NGC 5925 | [
"Astronomy"
] | 42 | [
"Norma (constellation)",
"Constellations"
] |
47,548,842 | https://en.wikipedia.org/wiki/NGC%206169 | NGC 6169 is an open cluster in the constellations Norma and Scorpius. It is 3280 light-years distant and thought to be around 32 million years old.
References
NGC 6169
6169
Norma (constellation) | NGC 6169 | [
"Astronomy"
] | 51 | [
"Constellations",
"Norma (constellation)",
"Sky regions",
"Asterisms (astronomy)"
] |
47,548,981 | https://en.wikipedia.org/wiki/Alexander%20Barvinok | Alexander I. Barvinok (born March 27, 1963) is a professor of mathematics at the University of Michigan.
Barvinok received his Ph.D. from St. Petersburg State University in 1988 under the supervision of Anatoly Moiseevich Vershik.
In 1999, Barvinok received the Presidential Early Career Award for Scientists and Engineers (PECASE) from President Bill Clinton.
Barvinok gave an invited talk at the 2006 International Congress of Mathematicians in Madrid.
In 2012, Barvinok became a Fellow of the American Mathematical Society.
In 2023, Barvinok left the American Mathematical Society by refusing to renew his membership in protest of its non-opposition to "DEI statements" and "compelled language", referencing his experiences in the Soviet Union.
References
Living people
Fellows of the American Mathematical Society
20th-century American mathematicians
21st-century American mathematicians
Russian mathematicians
University of Michigan faculty
Combinatorialists
Recipients of the Presidential Early Career Award for Scientists and Engineers
1963 births | Alexander Barvinok | [
"Mathematics"
] | 201 | [
"Combinatorialists",
"Combinatorics"
] |
47,549,038 | https://en.wikipedia.org/wiki/Orion%20Live%20Ink | Orion Live Ink is a digitisation method which uses character recognition technology and question paper rubrics to publish examination results. It is an OWASP Top 10 and CERT-IN Standards certified secure application (certificate number SB/OISPL/#3427).
Development
The solution consists of a digital pen, tablet and a special printed paper used as the top sheet on answer booklets. The digital pen is used by an examiner to write marks on the top sheet. The pen digitizes marks in real time and transfers data to the tablet. The allotted marks is displayed on the tablet in handwritten form as well as digitized format. Once the user validates marks in the tablet, the data is encrypted and transferred to the centralized server of the education board.
Features
The tablet handles question paper rubrics application, marks totalling and captures the date and time of evaluation.
Once the marks are validated, the tablet as well as the digital pen does not contain any residual data.
An OLICR pen and tablet set could be shared by several evaluators at an evaluation camp since the set would be required only at the time of writing the marks on the top sheet, which would take approximately less than a minute per answer script.
Evaluators will continue to check and correct answer sheets using traditional pen and paper method of evaluation. So, there is no additional learning cycle required while using OLICR devices.
Once the marks data is transferred to the central servers, it is immediately available for download in the education board's server.
Board exams and entrance tests
Board examination results is a deciding factor for students who aim to apply in reputed colleges and institutes for further studies. The national and state-level competitive entrance examinations are often held at a date convenient to the respective college or institute organising the examination. One of the criteria to apply for these examinations is the board examination results. So, students wait for their tenth or twelfth board examination results to enable them to apply for entrance examinations. To make schools relevant to changing trends, school education boards and councils have started adopting new technology and methods to enable faster and accurate marks publication. By doing this, the boards and councils earn the goodwill of their students and also enhance their credibility in the market.
Reception
The Council of Indian School Certificate Examination (CISCE), a premier private board of school education in India, has utilized OLICR technology for academic year 2016 to publish marks. With the use of this technology, the results was published 2 weeks earlier than expected.
The solution won the National Award for the Most Innovative Product in the Testing & Assessment Category held at the e-India Summit held at Kovalam, Kerala State, India in mid-November 2014.
See also
Character recognition
Rubric (academic)
Tablet computer
Data encryption
Data remanence
List of institutions of higher education in India
Board examination
Matriculation
References
External links
Automatic identification and data capture | Orion Live Ink | [
"Technology"
] | 589 | [
"Data",
"Automatic identification and data capture"
] |
47,550,744 | https://en.wikipedia.org/wiki/Penicillium%20severskii | Penicillium severskii is a species of fungus in the genus Penicillium.
References
severskii
Fungi described in 1981
Fungus species | Penicillium severskii | [
"Biology"
] | 34 | [
"Fungi",
"Fungus species"
] |
47,551,348 | https://en.wikipedia.org/wiki/Piricaudiopsis%20rhaphidophorae | Piricaudiopsis rhaphidophorae is a fungus occurring on dead branches of Rhaphidophora decursiva, hence its name. It was first found in a tropical forest in southern China. It differs from other Piricaudiopsis species in conidial morphology and in the proliferation of its conidiogenous cell. The presence or proliferation of the conidiogenous cells and the conidial appendages, as well as the height of its conidia are considered putative phylogenetic characters of this genus.
References
Further reading
Zhang, Kai, et al. "Xiuguozhangia, a new genus of microfungi to accommodate five Piricaudiopsis species." Mycotaxon 128.1 (2014): 131–135.
张凯.中国海南, 云南两省凋落枯枝暗色丝孢真菌分类研究. MS thesis. 山东农业大学, 2009.
External links
MycoBank
Fungal plant pathogens and diseases
Enigmatic Ascomycota taxa
Fungus species | Piricaudiopsis rhaphidophorae | [
"Biology"
] | 223 | [
"Fungi",
"Fungus species"
] |
47,551,358 | https://en.wikipedia.org/wiki/Piricaudiopsis%20rosae | Piricaudiopsis rosae is a fungus occurring on dead branches of Rosa chinensis, hence its name. It was first found in a tropical forest in southern China. It differs from other Piricaudiopsis species in conidial morphology and in the proliferation of its conidiogenous cell. The presence or proliferation of the conidiogenous cells and the conidial appendages, as well as the height of its conidia are considered putative phylogenetic characters of this genus.
References
Further reading
Zhang, Kai, et al. "Xiuguozhangia, a new genus of microfungi to accommodate five Piricaudiopsis species." Mycotaxon 128.1 (2014): 131–135.
张凯.中国海南, 云南两省凋落枯枝暗色丝孢真菌分类研究. MS thesis. 山东农业大学, 2009.
External links
MycoBank
Fungal plant pathogens and diseases
Enigmatic Ascomycota taxa
Fungus species | Piricaudiopsis rosae | [
"Biology"
] | 212 | [
"Fungi",
"Fungus species"
] |
47,551,381 | https://en.wikipedia.org/wiki/Piricaudiopsis%20punicae | Piricaudiopsis punicae is a fungus occurring on dead branches of Punica granatum, hence its name. It was first found in a tropical forest in southern China. It differs from other Piricaudiopsis species in conidial morphology and in the proliferation of its conidiogenous cell. The presence or proliferation of the conidiogenous cells and the conidial appendages, as well as the height of its conidia are considered putative phylogenetic characters of this genus.
References
Further reading
Zhang, Kai, et al. "Xiuguozhangia, a new genus of microfungi to accommodate five Piricaudiopsis species." Mycotaxon 128.1 (2014): 131–135.
张凯.中国海南, 云南两省凋落枯枝暗色丝孢真菌分类研究. MS thesis. 山东农业大学, 2009.
External links
MycoBank
Fungal plant pathogens and diseases
Enigmatic Ascomycota taxa
Fungus species | Piricaudiopsis punicae | [
"Biology"
] | 215 | [
"Fungi",
"Fungus species"
] |
47,551,734 | https://en.wikipedia.org/wiki/Highest%20temperature%20recorded%20on%20Earth | The highest temperature recorded on Earth has been measured in three major ways: air, ground, and via satellite observation. Air measurements are used as the standard measurement due to persistent issues with unreliable ground and satellite readings. Air measurements are noted by the World Meteorological Organization (WMO) and Guinness World Records among others as the standard to be used for determining the official record. The current official highest registered air temperature on Earth is , recorded on 10 July 1913 at Furnace Creek Ranch, in Death Valley in the United States. For few years, a former record that was measured in Libya had been in place, until it was decertified in 2012 based on evidence that it was an erroneous reading. This finding has since raised questions about the legitimacy of the 1913 record measured in Death Valley, with several meteorological experts asserting that there were similar irregularities. The WMO has stood by the record as official pending any future investigative results. If the current record were to be decertified then the holder would be a tie at , recorded both at Furnace Creek and in Kuwait.
Several unverified temperatures that exceed the current record have also been recorded. These include historical claims that were never authenticated due to the equipment available at the time and unverified scientific claims.
History
The standard measuring conditions for temperature are in the air, above the ground, and shielded from direct sunlight. Global surface temperatures as a whole have been monitored since the 1880s when record keeping began. According to the World Meteorological Organization (WMO), the highest registered air temperature on Earth was in Furnace Creek Ranch, California, located in Death Valley in the United States, on 10 July 1913. This record was surpassed by a reading of , registered on 13 September 1922, in ʽAziziya, Libya. Ninety years later, this record was decertified, making the former reading in Death Valley the world's highest official temperature again. The decertification of the former record in Libya has since cast doubt on the validity of the 1913 recording. If the 1913 record were to be decertified, the highest established recorded air temperature on Earth would be , also recorded in Death Valley on 20 June 2013, and in Mitribah, Kuwait on 21 July 2016. There have since been higher readings of in August 2020 and July 2021, both at Furnace Creek, that are pending validation.
Measurements have also been taken in two other ways via ground and satellite readings. Temperatures measured directly on the ground may exceed air temperatures by . The theoretical maximum possible ground surface temperature has been estimated to be between for dry, darkish soils of low thermal conductivity. While there is no highest confirmed ground temperature, a reading of – the highest ever among unverified claims – was allegedly recorded in Furnace Creek Ranch on 15 July 1972. Temperature measurements via satellite also tend to capture the occurrence of higher records but, due to complications involving the satellite's altitude loss (a side effect of atmospheric friction), these measurements are often considered less reliable than ground-positioned thermometers. Satellite measurements of ground temperature taken between 2003 and 2009, taken with the MODIS infrared spectroradiometer on the Aqua satellite, found a maximum temperature of , which was recorded in 2005 in the Lut Desert, Iran. The Lut Desert was also found to have the highest maximum temperature in 5 of the 7 years measured (2004, 2005, 2006, 2007, and 2009). These measurements reflect averages over a large region and so are lower than the maximum point surface temperature.
Issues
In the early 21st century, prior recordings for the highest temperature on Earth were investigated as probable misreadings. From 1922 until 2012, the WMO record for the highest official temperature on Earth was , registered on 13 September 1922, in ʽAziziya, Libya. This record was decertified by the WMO in January 2012 after investigation concluded that an inexperienced observer probably misread a new instrument that they had not been trained to interpret. The decertification of this former record led researchers to also investigate the former and current recordings made in Death Valley in 1913. One of the earliest objections came in 1949 by Dr. Arnold Court, who concluded that the temperature may have been the result of a sandstorm that occurred at the time. Court stated that "such a storm may have caused superheated surface materials to hit upon the temperature in the shelter." Modern weather historians such as Christopher C. Burt and William Taylor Reid have also claimed that the 1913 Death Valley reading is "a myth", and is at least too high. The WMO has come out in support of the current record stating that "We accept that Death Valley temperature extreme record. If any new materials on it surface, we will be prepared to open an investigation, but at this time all available evidence points to its legitimacy."
Unverified claims
The following are unverified claims of extreme heat over the current world record of . These include historical claims that were never authenticated due to the equipment available at the time and unverified scientific claims. Amateur readings have also been done through social media that claimed extreme temperatures which were later discredited. Videos were posted in one instance that allegedly showed street lights melting or trees bursting into flames. These were later disproven by meteorologists who tied the "evidence" to other unrelated prior events that had taken place. All of the recordings listed before 1972 were allegedly caused by a sudden localized increase in air temperature near the surface, known as a heat burst.
See also
Desert climate
Heat wave
Highest temperatures ever recorded
Lowest temperature recorded on Earth
Lowest temperatures ever recorded
Orders of magnitude (temperature)
Explanatory notes
References
Temperature
Weather extremes of Earth
Climate and weather statistics | Highest temperature recorded on Earth | [
"Physics",
"Chemistry"
] | 1,142 | [
"Scalar physical quantities",
"Temperature",
"Thermodynamic properties",
"Physical phenomena",
"Physical quantities",
"Weather",
"SI base quantities",
"Intensive quantities",
"Climate and weather statistics",
"Thermodynamics",
"Wikipedia categories named after physical quantities"
] |
47,551,794 | https://en.wikipedia.org/wiki/Breast%20crawl | Breast crawl is the instinctive movement of a newborn mammal toward the nipple of its mother for the purpose of latching on to initiate breastfeeding. In humans, if the newborn is laid on its mother's abdomen, movements commence at 12 to 44 minutes after birth, with spontaneous suckling being achieved roughly 27 to 71 minutes after birth.
Background
The Baby Friendly Hospital Initiative, developed by the World Health Organization and UNICEF, recommends that all babies have access to immediate skin-to-skin contact (SSC) following vaginal or Caesarean section birth. Immediate SSC after a Caesarean that used spinal or epidural anesthesia is achievable because the mother remains alert; however, after the use of general anesthesia, the newborn should be placed skin to skin as soon as the mother becomes alert and responsive.
If the mother is not immediately able to begin SSC, her partner or other helper can assist or place the infant SSC on their chest or breast. It is recommended that SSC be facilitated immediately after birth, as this is the time when the newborn is most likely to follow its natural instincts to find and attach to the breast and then breastfeed.
To find the nipple, the newborn uses a variety of sensory stimuli: visual (the sight of the mother's face and areola); auditory (the sound of its mother's voice); and olfactory (the scent of the areola, which resembles that of amniotic fluid).
Nine stages of breast crawl
Newborn babies go through nine distinct stages after birth within the first hour or so:
Birth cry: Intense crying just after birth
Relaxation phase: Infant resting and recovering. No activity of mouth, head, arms, legs or body
Awakening phase: Infant begins to show signs of activity. Small thrusts of head: up, down, from side-to-side. Small movements of limbs and shoulders
Active phase: Infant moves limbs and head, is more determined in movements. Rooting activity, ‘pushing’ with limbs without shifting body
Crawling phase: ‘Pushing’ which results in shifting body
Resting phase: Infant rests, with some activity, such as mouth activity, sucks on hand
Familiarization: Infant has reached areola/nipple with mouth positioned to brush and lick areola/nipple
Suckling phase: Infant has taken nipple in mouth and commences suckling
Sleeping phase: The baby has closed its eyes. Mother may also fall asleep.
References
Breastfeeding
Ethology
Babycare | Breast crawl | [
"Biology"
] | 503 | [
"Behavioural sciences",
"Ethology",
"Behavior"
] |
47,552,191 | https://en.wikipedia.org/wiki/QX%20Normae | QX Normae is an active low mass X ray binary in the constellation Norma. It is composed of a neutron star and a star smaller and cooler than the Sun. The X-ray component, known as 4U 1608–52, was discovered in the early 1970s, while the visual component, QX Normae, was discovered in 1977. By analysing the interstellar extinction between Earth and the system, Güver and colleagues calculated the most likely distance to be 5.8 kpc (19,000 light-years), and the neutron star's mass to be 1.74 ± 0.14 times that of the Sun and radius to be a mere 9.3 ± 1.0 km.
References
Norma (constellation)
Normae, QX | QX Normae | [
"Astronomy"
] | 158 | [
"Norma (constellation)",
"Constellations"
] |
47,552,633 | https://en.wikipedia.org/wiki/List%20of%20people%20associated%20with%20PARC | Many notable computer scientists and others have been associated with the Palo Alto Research Center Incorporated (PARC), formerly Xerox PARC. They include:
Nina Amenta (at PARC 1996–1997), researcher in computational geometry and computer graphics
Anne Balsamo (at PARC 1999–2002), media studies scholar of connections between art, culture, gender, and technology
Patrick Baudisch (at PARC 2000–2001), in human–computer interaction
Daniel G. Bobrow (at PARC 1972–2017), artificial intelligence researcher
Susanne Bødker (at PARC 1982–1983), researcher in human–computer interaction
David Boggs (at PARC 1972–1982), computer network pioneer, coinventor of Ethernet
Anita Borg (at PARC 1997–2003), computer systems researcher, advocate for women in computing
John Seely Brown (at PARC 1978–2000), researcher in organizational studies, chief scientist of Xerox
Bill Buxton (at PARC 1989–1994), pioneer in human–computer interaction
Stuart Card (at PARC 1974-2010), applied human factors in human–computer interaction
Robert Carr (at PARC in late 1970s), CAD and office software designer
Ed Chi (at PARC 1997–2011), researcher in information visualization and the usability of web sites
Elizabeth F. Churchill (at PARC 2004–2006), specialist in human-computer interaction and social computing
Lynn Conway (at PARC 1973–1982), VLSI design pioneer and transgender activist
Franklin C. Crow (at PARC circa 1982–1990), computer graphics expert who did early research in antialiasing
Pavel Curtis (at PARC 1983–1996), pioneer in text-based online virtual reality systems
Doug Cutting (at PARC 1990-1994), creator of Nutch, Lucene, and Hadoop
Steve Deering (at PARC circa 1990–1996), internet engineer, lead designer of IPv6
L Peter Deutsch (at PARC 1971–1986), implementor of LISP 1.5, Smalltalk, and Ghostscript
David DiFrancesco (at PARC 1972–1974), worked with Richard Shoup on PAINT, cofounded Pixar
Paul Dourish (at PARC mid-1990s), researcher at the intersection of computer science and social science
W. Keith Edwards (at PARC 1996–2004), researcher in human-computer interaction and ubiquitous computing
Jerome I. Elkind (at PARC 1971–1978), head of the Computer Science Laboratory at PARC
Clarence Ellis (at PARC 1976–1984), first African American CS PhD, pioneered computer-supported cooperative work
David Em (at PARC 1975), computer artist, first fine artist to create a computer model of a 3d character
Bill English (at PARC 1971–1989), co-invented computer mouse
David Eppstein (at PARC 1989–1990), researcher in computational geometry and graph algorithms
John Ellenby (at PARC 1975–1978), Led AltoII development, 1979 founded GRID Systems
Matthew K. Franklin (at PARC 1998–2000), developed pairing-based elliptic-curve cryptography
Gaetano Borriello (at PARC 1980–1987), developed Open Data Kit
Richard Fikes (at PARC 1976-1983), leader in representation and use of knowledge in computer systems, Professor Emeritus, Stanford University
Sean R. Garner (at PARC circa 2009– ), researcher in photovoltaics and sustainable engineering
Charles Geschke (at PARC 1972–1980), invented page description languages, cofounded Adobe
Adele Goldberg (at PARC 1973–1986), codesigned Smalltalk, president of ACM
Jack Goldman (at PARC 1970–), Xerox chief scientist 1968–1982, founded PARC in 1970
Bill Gosper (at PARC 1977–1981), founded the hacker community, pioneered symbolic computation
Rich Gossweiler (at PARC 1997–2000), software engineer, expert in interaction design
Rebecca Grinter (at PARC 2000–2004), researcher in human-computer interaction and computer-supported cooperative work
Neil Gunther (at PARC 1982–1990), developed open-source performance modeling software
Jürg Gutknecht (at PARC 1984–1985), programming language researcher, designer, with Niklaus Wirth
Marti Hearst (at PARC 1994–1997), expert in computational linguistics and search engine user interfaces
Jeffrey Heer (at PARC 2001-2005), expert in information visualization and interactive data analysis
Bruce Horn (at PARC 1973–1981), member of original Apple Macintosh design team
Bernardo Huberman (at PARC circa 1982–2000), applied chaos theory to web dynamics
Dan Ingalls (at PARC circa 1972–1984), implemented Smalltalk virtual machine, invented bit blit
Van Jacobson (at PARC 2006– ), developed internet congestion control protocols and diagnostics
Natalie Jeremijenko (at PARC 1995), installation artist
Ted Kaehler (at PARC 1972–1985), developed key systems for original Smalltalk, later Apple HyperCard, Squeak
Ronald Kaplan (at PARC 1974–2006), expert in natural language processing, helped develop Interlisp
Jussi Karlgren (at PARC 1991-1992), known for work on stylistics, evaluation of search technology, and statistical semantics
Lauri Karttunen (at PARC 1987–2011), developed finite state morphology in computational linguistics
Alan Kay (at PARC 1971–1981), pioneered object-oriented programming and graphical user interfaces
Martin Kay (at PARC 1974–2002 ), expert on machine translation and computational linguistics
Gregor Kiczales (at PARC 1984–2002), invented aspect-oriented programming
Ralph Kimball (at PARC 1972–1982), designed first commercial workstation with mice, icons, and windows
András Kornai (at PARC 1988-1991), mathematical linguist
Butler Lampson (at PARC 1971–1983), won Turing Award for his development of networked personal computers
David M. Levy (at PARC 1984–1999), researcher on information overload
Jia Li (at PARC 1999–2000), researcher in computer vision and image retrieval
Cristina Lopes (at PARC 1995–2002), researcher in aspect-oriented programming and ubiquitous computing
Richard Francis Lyon (at PARC 1977–1981), built the first optical mouse
Jock D. Mackinlay (at PARC 1986–2004) researcher in information visualization
Cathy Marshall (at PARC circa 1989–2000), researcher on hypertext and personal archiving
Edward M. McCreight (at PARC 1971–1989) co-invented B-trees
Scott A. McGregor (at PARC 1978–1983) worked on Xerox Star, Viewers for Cedar and then Windows 1.0 at Microsoft
Sheila McIlraith (at PARC 1997–1998), researcher in artificial intelligence and the semantic web
Ralph Merkle (at PARC 1988–1999), invented public key cryptography and cryptographic hashing
Diana Merry (at PARC circa 1971–1986), helped develop Smalltalk, co-invented bit blit
Robert Metcalfe (at PARC 1972–1979), co-invented Ethernet, formulated Metcalfe's Law
James G. Mitchell (at PARC 1971–1984), developed WATFOR compiler, Mesa (programming language), Spring (operating system), ARM RISC chip
Louis Monier (at PARC 1983–1989), founded AltaVista search engine
J Strother Moore (at PARC 1973-1976), text editing, Interlisp VM, string searching, theorem proving
Thomas P. Moran (at PARC 1974–2001), founded journal Human-Computer Interaction
James H. Morris (at PARC 1974–1982), co-invented KMP string matching algorithm and lazy evaluation
Elizabeth Mynatt (at PARC 1995–1998), studied digital family portraits and ubiquitous computing
Greg Nelson (at PARC 1980–1981), satisfiability modulo theories, extended static checking, program verification, Modula-3, theorem prover
Martin Newell (at PARC 1979–1981), graphics expert who created the Utah teapot
William Newman (at PARC 1973–1979), Graphics and HCI researcher, developed drawing and page description software
Tina Ng (at PARC 2006–2015), expert on additive manufacture of flexible electronics
Geoffrey Nunberg (at PARC 1987–2001), linguist known for his work on lexical semantics
Severo Ornstein (at PARC 1976–1983), founding head of Computer Professionals for Social Responsibility
Valeria de Paiva (at PARC 2000–2008), uses logic and category theory to model natural language
George Pake (at PARC 1970–1986), pioneer in nuclear magnetic resonance, founding director of PARC
Jan O. Pedersen (at PARC circa 1990-1996), researcher in search system technology and algorithms
Peter Pirolli (at PARC 1991–2016 ), developed information foraging theory
Calvin Quate (at PARC 1983–1994), invented the atomic force microscope
Ashwin Ram (at PARC circa 2011–2016 ), researcher on artificial intelligence for health applications
Trygve Reenskaug (at PARC 1978–1979), formulated model–view–controller user interface design
George G. Robertson (at PARC circa 1988–1995), information visualization expert
Daniel M. Russell (at PARC 1982–1993), AI and UI research; later at Apple, then at Google, where he calls himself a search anthropologist
Eric Schmidt (at PARC 1982–1983), CEO of Google and chairman of Alphabet
Ronald V. Schmidt (at PARC 1980–1985), computer network engineer who founded SynOptics
Michael Schroeder (at PARC circa 1977–1985), co-invented Needham–Schroeder protocol for encrypted networking
Bertrand Serlet (at PARC 1985–1989), led the Mac OS X team
Scott Shenker (at PARC 1984–1998), leader in software-defined networking
John Shoch (at PARC 1971–1980), developed an important predecessor of TCP/IP networking
Richard Shoup (at PARC 1971–1978), invented SUPERPAINT and the first 8 bit Frame Buffer (picture memory), 1979 cofounded Aurora
Charles Simonyi (at PARC 1972-1981), led the creation of Microsoft Office
Alvy Ray Smith (at PARC 1974), cofounded Pixar
Brian Cantwell Smith (at PARC 1982–1996), invented introspective programming and researches computational metaphors
David Canfield Smith (at PARC 1975), invented interface icons, programming by demonstration, worked on graphical user interface, Xerox Star
Robert Spinrad (at PARC 1978–1982), designed vacuum tube computers, directed PARC
Bob Sproull (at PARC 1973–1977), designed early head-mounted display, wrote widely used computer graphics textbook
Jessica Staddon (at PARC 2001–2010), information privacy researcher
Gary Starkweather (at PARC 1970–1988), invented laser printers and color management
Maureen C. Stone (at PARC circa 1980–1998), expert in color modeling
Lucy Suchman (at PARC 1980–2000), researcher on human factors, cybercultural anthropology, and feminist theory
Bert Sutherland (at PARC 1975–1981), brought social scientists to PARC
Robert Taylor (at PARC 1970–1983), managed early ARPAnet development, founded DEC Systems Research Center
Warren Teitelman (at PARC 1972–1984), designed Interlisp
Shang-Hua Teng (at PARC 1991–1992), invented smoothed analysis of algorithms and near-linear-time Laplacian solvers
Larry Tesler (at PARC 1973–1980), developed Object Pascal and Apple Newton
Chuck Thacker (at PARC 1971–1983), chief designer of Alto, co-invented Ethernet
John Warnock (at PARC 1978–1982), cofounded Adobe
Mark Weiser (at PARC 1987–1999), invented ubiquitous computing
Niklaus Wirth (at PARC 1976–1977 and 1984–1985), designed Pascal and other programming languages
Frances Yao (at PARC 1979–1999), researcher in computational geometry and combinatorial algorithms
Nick Yee (at PARC 2005-2012), researcher in psychology and sociology of virtual environments
Annie Zaenen (at PARC 2001–2011), researcher on linguistic encoding of temporal and spatial information
Lixia Zhang (at PARC 1989–1996), computer networking pioneer
References
PARC | List of people associated with PARC | [
"Technology"
] | 2,486 | [
"Computing-related lists",
"Lists of computer scientists"
] |
56,062,910 | https://en.wikipedia.org/wiki/67N6E | 67N6E GAMMA DE is a 3D radar system developed by VNIIRT for the Russian Armed Forces. It is a mobile UHF L band Active electronically scanned array for the purpose of air defense support.
References
Ground radars
Russian military radars
Warning systems
Almaz-Antey products | 67N6E | [
"Technology",
"Engineering"
] | 60 | [
"Warning systems",
"Safety engineering",
"Measuring instruments"
] |
56,064,069 | https://en.wikipedia.org/wiki/Purging%20%28gas%29 | In fire and explosion prevention engineering, purging refers to the introduction of an inert (i.e. non-combustible) purge gas into a closed system (e.g. a container or a process vessel) to prevent the formation of an ignitable atmosphere. Purging relies on the principle that a combustible (or flammable) gas is able to undergo combustion (explode) only if mixed with air in the right proportions. The flammability limits of the gas define those proportions, i.e. the ignitable range.
Purge into service
Assume a closed system (e.g. a container or process vessel), initially containing air, which shall be prepared for safe introduction of a flammable gas, for instance as part of a start-up procedure. The system can be flushed with an inert gas to reduce the concentration of oxygen so that when the flammable gas is admitted, an ignitable mixture cannot form. In NFPA 56, this is known as purge-into-service. In combustion engineering terms, the admission of inert gas dilutes the oxygen below the limiting oxygen concentration.
Purge out of service
Assume a closed system containing a flammable gas, which shall be prepared for safe ingress of air, for instance as part of a shut-down procedure. The system can be flushed with an inert gas to reduce the concentration of the flammable gas so that when air is introduced, an ignitable mixture cannot form. In NFPA 56 this is known as purge-out-of-service.
Benefits of having two purging terms
It is useful with two terms for purging because purge-out-of-service requires much larger quantities of inert agent than purge-into-service. The terminology of German standards refers to purge-into-service as partial inerting, and purge-out-of-service as total inerting, clearly indicating the difference between the two purging practices, although the choice of the term inerting, rather than purging, can be confusing, see below.
Comparison with other explosion prevention practices
Prevention of accidental fires and explosions can also be achieved by controlling sources of ignition. Purging with an inert gas provides a higher degree of safety however, because the practice ensures that an ignitable mixture never forms. Purging can therefore be said to rely on primary prevention, reducing the possibility of an explosion, whereas control of sources of ignition relies on secondary prevention, reducing the probability of an explosion. Primary prevention is also known as inherent safety.
Confusion with inerting
The purge gas is inert, i.e. by definition non-combustible, or more precisely, non-reactive. The most common purge gases commercially available in large quantities are nitrogen and carbon dioxide. Other inert gases, e.g. argon or helium may be used. Nitrogen and carbon dioxide are unsuitable purge gases in some applications, as these gases may undergo chemical reaction with fine dusts of certain light metals.
Because an inert purge gas is used, the purge procedure may (erroneously) be referred to as inerting in everyday language. This confusion may lead to dangerous situations. Carbon dioxide is a safe inert gas for purging. Carbon dioxide is an unsafe inert gas for inerting, as it may ignite the vapors and result in an explosion.
See also
ATEX
Flammability limits
Limiting oxygen concentration
Inerting (gas)
External links
Fighting Smoldering Fires in Silos – A Cautionary Note on Using Carbon Dioxide. Guest post at www.mydustexplosionresearch.com blog, Nov 27, 2017
References
Explosion protection
Fire
Safety | Purging (gas) | [
"Chemistry",
"Engineering"
] | 769 | [
"Explosion protection",
"Combustion engineering",
"Combustion",
"Explosions",
"Fire"
] |
56,064,706 | https://en.wikipedia.org/wiki/Methyl%20dimethyldithiocarbamate | Methyl dimethyldithiocarbamate is the organosulfur compound with the formula (CH3)2NC(S)SCH3. It is the one of simplest dithiocarbamic esters. It is a white volatile solid that is poorly soluble in water but soluble in many organic solvents. It was once used as a pesticide.
Methyl dimethyldithiocarbamate can be prepared by methylation of salts of dimethyldithiocarbamate:
(CH3)2NCS2Na + (CH3O)2SO2 → (CH3)2NC(S)SCH3 + Na[CH3OSO3]
It can also be prepared by the reaction of a tetramethylthiuram disulfide with methyl Grignard reagents:
[(CH3)2NC(S)S]2 + CH3MgBr → (CH3)2NC(S)SCH3 + (CH3)2NCS2MgBr
References
Dithiocarbamates | Methyl dimethyldithiocarbamate | [
"Chemistry"
] | 219 | [
"Dithiocarbamates",
"Functional groups"
] |
56,065,761 | https://en.wikipedia.org/wiki/Inerting%20%28gas%29 | In fire and explosion prevention engineering, inerting refers to the introduction of an inert (non-combustible) gas into a closed system (e.g. a container or a process vessel) to make a flammable atmosphere oxygen deficient and non-ignitable.
Inerting relies on the principle that a combustible (or flammable) gas is able to undergo combustion (explode) only if mixed with air in the right proportions. The flammability limits of the gas define those proportions, i.e. the ignitable range. In combustion engineering terms, the admission of inert gas can be said to dilute the oxygen below the limiting oxygen concentration.
Inerting differs from purging. Purging, by definition, ensures that an ignitable mixture never forms. Inerting makes an ignitable mixture safe by introduction of an inert gas.
Certain inert gases are unsuitable for inerting
Because the mixture by definition is ignitable before inerting commence, it is imperative that the inerting procedure does not introduce a potential source of ignition, or an explosion will occur.
NFPA 77 states that carbon dioxide from high-pressure cylinders or fire extinguishers should never be used to inert a container or vessel. The release of carbon dioxide may generate static electricity with enough energy to ignite the mixture, resulting in an explosion. The release of for fire fighting purposes has led to several accidental explosions of which the 1954 Bitburg explosion may be the most devastating.
Other unsafe processes that may generate static electricity include pneumatic transport of solids, a release of pressurized gas with solids, industrial vacuum cleaners, and spray painting operations.
Other uses
The term inerting is often loosely used for any application involving an inert gas, not conforming with the technical definitions in NFPA standards. For example, marine tankers carrying low-flash products like crude oil, naphtha, or gasoline have inerting systems on board. During the voyage, the vapor pressure of these liquids is so high, that the atmosphere above the liquid (the headspace) is too rich to burn, the atmosphere is unignitable. This may change during unloading. When a certain volume of liquid is drawn from a tank, a similar volume of air will enter the tank's headspace, potentially creating an ignitable atmosphere.
The inerting systems use an inert gas generator to supply inert make-up gas instead of air. This procedure is often referred to as inerting. Technically, the procedure ensures that the atmosphere in the tank's headspace remains unignitable. The gas mixture in the headspace is not inert per se, it's just unignitable. Because of its content of flammable vapors, it will burn if mixed with air. Only if enough inert gas is supplied as part of a purge-out-of-service procedure, will it be unable to burn when mixed with air.
See also
ATEX
Flammability limits
Limiting oxygen concentration
Purging (gas)
1954 Bitburg explosion (jet fuel storage tank)
The 1966 explosion of the naphtha tanker MV Alva Cape
External links
Fighting Smoldering Fires in Silos – A Cautionary Note on Using Carbon Dioxide. Guest post at www.mydustexplosionresearch.com blog, Nov 27, 2017
References
Explosion protection
Fire
Process safety | Inerting (gas) | [
"Chemistry",
"Engineering"
] | 714 | [
"Explosion protection",
"Safety engineering",
"Combustion engineering",
"Combustion",
"Process safety",
"Explosions",
"Chemical process engineering",
"Fire"
] |
56,065,871 | https://en.wikipedia.org/wiki/Berkeley%20SETI%20Research%20Center | The Berkeley SETI Research Center (BSRC) conducts experiments searching for optical and electromagnetic transmissions from intelligent extraterrestrial civilizations. The center is based at the University of California, Berkeley.
The Berkeley SETI Research Center has several SETI searches operating at various wavelengths, from radio, through infrared, to visible light. These include SERENDIP, SEVENDIP, NIROSETI, Breakthrough Listen, and SETI@home. The research center is also involved in the development of new telescopes and instrumentation.
The Berkeley SETI Research Center is independent of, but collaborates with, researchers at the SETI Institute. No unambiguous signals from extraterrestrial intelligence have been found.
Breakthrough Listen
The Berkeley SETI Research Center also hosts the Breakthrough Listen program, which is a ten-year initiative with $100 million funding begun in July 2015 to actively search for intelligent extraterrestrial communications in the universe, in a substantially expanded way, using resources that had not previously been extensively used for the purpose. It has been described as the most comprehensive search for alien communications to date. Announced in July 2015, the project is observing for thousands of hours every year on two major radio telescopes, the Green Bank Observatory in West Virginia, the Parkes Observatory in Australia, and the Automated Planet Finder telescope.
SETI@home
The center also created the SETI@home, an Internet-based public volunteer computing project employing the BOINC software platform, hosted by their Space Sciences Laboratory. Its purpose is to analyze radio data from radio telescopes for signs of extraterrestrial intelligence.
SERENDIP
The SERENDIP program takes advantage of ongoing "mainstream" radio telescope observations and analyzes deep space radio telescope data that it obtains while other astronomers are using the telescope. SERENDIP observations have been conducted at frequencies between 400 MHz and 5 GHz, with most observations near the so-called Cosmic Water Hole (1.42 GHz (21 cm) neutral hydrogen and 1.66 GHz hydroxyl transitions).
SEVENDIP
SEVENDIP, which stands for Search for Extraterrestrial Visible Emissions from Nearby Developed Intelligent Populations, was a project using visible wavelengths to search for extraterrestrial life's intelligent signals from outer space.
NIROSETI
The NIROSETI (Near-InfraRed Optical Search for Extraterrestrial Intelligence) program searches for artificial signals in the optical (visible) and near infrared (NIR) wavebands of the electromagnetic spectrum. It uses the Nickel 1-m telescope at the Lick Observatory in California, USA. The instrument saw its first light on 15 March 2015 and was commissioned in January 2016.
The NIROSETI instrument employs a new generation of near-infrared (900 to 1700 nm) detectors, cooled at -25 °C, that have a high speed response (>1 GHz) and gain comparable to photomultiplier tubes, while also producing very low noise, and significantly reducing false positives. Its field-of-view is 2.5"x2.5" each, and focuses
on detecting short (nanosecond) pulsed laser emissions. The NIROSETI instrument is also being used to study variability of very short natural near-infrared transient phenomena.
See also
References
External links
Berkeley SETI Research Center Highlights, 5 min video by Berkeley University at YouTube.
Search for Extraterrestrial Intelligence at Home (SETI@Home)
Stephen Hawking and Russian tycoon Yuri Milner kick off new search for E.T., $100 million funding to search star catalogue using SETI@home software, July 2015.
Search for extraterrestrial intelligence
Astrobiology
University of California, Berkeley
Radio astronomy
Research institutes in the San Francisco Bay Area | Berkeley SETI Research Center | [
"Astronomy",
"Biology"
] | 751 | [
"Origin of life",
"Speculative evolution",
"Astrobiology",
"Radio astronomy",
"Biological hypotheses",
"Astronomical sub-disciplines"
] |
56,066,481 | https://en.wikipedia.org/wiki/Sara%20Rankin | Sara Margaret Rankin is a professor of Leukocyte and Stem Cell Biology at Imperial College London. She is known for her work in stimulating endogenous bone marrow stem cells to repair the body. Rankin identifies as being neurodiverse.
Personal life
After visiting the Bristol Radiotherapy Centre as a teenager, Rankin knew she wanted a career in research. Since 2011, Rankin has identified as being neurodiverse, with characteristics of dyslexia and dyspraxia.
Education
Rankin received first class honours for a BSc in pharmacology at King's College London in 1985. Rankin continued at the same institution for her PhD, completing in 1989.
Research
After her PhD, Rankin moved to the University of California, San Diego as a postdoctoral research fellow. She joined Imperial as a postdoctoral researcher in 1992.
, Rankin is based in the Faculty of Medicine at the National Heart and Lung Institute (NHLI), where she was appointed Professor in 2010. Rankin and her team are trying to navigate the mesenchymal stem cells found in bone marrow to injured sites around the body, where they can promote regeneration in nearby tissue and dampen the immune system. The regulated movement of stem cells from bone marrow to sites of tissue damage could treat broken bones or heart disease.
She is the lead for biology and therapeutics at the Blast Injury Centre at Imperial College London, where she studies heterotopic ossification. She is a leader of the London Stem Cell Network. Rankin holds research grants from the Wellcome Trust, European Commission and British Legion.
Public engagement
Rankin is the NHLI division lead for Outreach and engagement. She is the co-founder of The Curious Act, a science public engagement initiative who run creative science-based activities for the public. In 2011, she collaborated with Gina Czarnecki, acting as the lead scientist in "Wasted". In 2012 Czarnecki and Rankin created Palaces, a crystal resin sculpture embedded with milk teeth donated by children across the UK.
Rankin and The Curious Act have hosted a number of science-themed pop-up shops. The Heart and Lung Repair Shop, a two-week pop-up science shop in Hammersmith's Kings Mall, opened in July 2014. The Heart and Lung Convenience Store opened in Hammersmith in 2015.
In 2017 Rankin launched 2eMpowerUK, which runs STEM workshops for neurodiverse teenagers.
Honours and awards
Her awards and honours include:
2016 Imperial College London Collaboration Award for Societal Engagement
2011 Wellcome Trust Senior Investigator Award
2010 Imperial College London Rector's Award for Excellence in Pastoral Care
2019 Imperial College Julia Higgins Award for contribution to gender equality
References
21st-century British biologists
21st-century British women scientists
Academics of Imperial College London
Alumni of King's College London
British women biologists
Fellows of the Royal Society of Biology
Living people
Stem cell researchers
Year of birth missing (living people)
Scientists with dyslexia
British scientists with disabilities | Sara Rankin | [
"Biology"
] | 594 | [
"Stem cell researchers",
"Stem cell research"
] |
56,066,767 | https://en.wikipedia.org/wiki/Michael%20Hartshorn | Michael Philip Hartshorn (10 September 1936 – 15 December 2017) was a British-born New Zealand organic chemist. He was awarded the Hector Memorial Medal by the Royal Society of New Zealand in 1973.
Early life and education
Born in Keresley on the outskirts of Coventry, Warwickshire, England, on 10 September 1936, Hartshorn was the son of Bernard Hartshorn and Christine Evelyn Hartshorn (née Bennett). He studied at Imperial College London, from where he graduated BSc and ARCS, and at University College, Oxford, where he obtained a DPhil in 1960. His doctoral thesis was titled Steroid hormone analogues.
Hartshorn married Jacqueline Joll in 1963, and the couple went on to have four sons. He became a naturalised New Zealand citizen in 1965.
Academic and research career
Hartshorn was appointed as a lecturer in the Department of Chemistry at the University of Canterbury in Christchurch in 1960, and rose to become a professor in 1972. When he retired in 1996 he was made a professor emeritus.
Hartshorn's research centred on reaction mechanisms. He investigated the chemical rearrangement of steroids, cyclic sulfites, monoterpenes and acetylenic alcohols. His research included the ipso nitration of aromatic hydrocarbons and phenols, and their reactions with fuming nitric acid and nitrogen dioxide, as well as the chlorination of polysubstituted phenols. He also studied the reactions of cation radicals arising from the photolysis of aromatic hydrocarbons.
Hartshorn was elected a fellow of the New Zealand Institute of Chemistry in 1969, and a fellow of the Royal Society of New Zealand the following year. In 1973, he received the Hector Memorial Medal, at that time the highest honour for scientific excellence awarded by the Royal Society of New Zealand.
Death
Hartshorn died in Christchurch on 15 December 2017.
References
1936 births
2017 deaths
People from Coventry
Alumni of Imperial College London
Alumni of University College, Oxford
English chemists
English emigrants to New Zealand
Academic staff of the University of Canterbury
Naturalised citizens of New Zealand
New Zealand chemists
Organic chemists
Fellows of the Royal Society of New Zealand
Fellows of the New Zealand Institute of Chemistry | Michael Hartshorn | [
"Chemistry"
] | 452 | [
"Organic chemists",
"British organic chemists",
"New Zealand organic chemists"
] |
56,066,942 | https://en.wikipedia.org/wiki/Disc%20cutting%20lathe | A disc cutting lathe is a device used to transfer an audio signal to the modulated spiral groove of a blank master disc for the production of phonograph records. Disc cutting lathes were also used to produce broadcast transcription discs and for direct-to-disc recording.
Overview
Disc cutting lathes utilize an audio signal, sent through a cutting amplifier to the cutter head, which controls the cutting stylus. The cutting stylus engraves a modulated spiral groove corresponding to the audio signal into the lacquer coating of the master disc. The direct metal mastering (DMM) process uses a copper-coated rather than lacquer-coated disc. Before lacquer discs, master recordings were cut into blank wax discs.
Once complete, this master disc is used to produce matrices from which the record is pressed. For all intents and purposes, the finished record is a facsimile of this master disc.
History
Prior to the success of Western Electric's "Westrex" system, master discs were produced acoustically and without electricity. In 1921, John J. Scully, a former Columbia Phonograph Company employee, designed and built a weight-driven lathe specifically designed for use by phonograph manufacturers. The first Scully lathe was sold to Cameo Records. John's son, Lawrence, founded Scully Recording Instruments.
In 1924, Western Electric purchased a Scully weight-driven lathe to demonstrate their "Westrex" cutter head and electronics for both the Columbia Phonograph Company and Victor Talking Machine Company. Both companies began using the Westrex system for recording sessions in 1925 after agreeing to license the system from Western Electric.
In 1931, German manufacturer Georg Neumann & Co. introduced the AM31 disc-cutting lathe, which employed a direct-drive design. Two years later, Neumann introduced a portable lathe capable of making recordings on location. Imports of Neumann lathes into the United States were restricted, however, and Neumann lathes were not imported to the United States until the 1960s. Scully dominated the U.S. marketplace for professional recording lathes from the 1930s to the 1960s, and almost all American lacquer masters were cut using a Scully lathe, often fitted with the Westrex cutter head and electronics.
In 1947, the Presto 1D, Fairchild 542, and Cook feedback cutters represented major improvements in disc-cutting technology. In 1950 Scully Recording Instruments introduced a disc cutting lathe with variable pitch, which made it possible to vary the width of the grooves (i.e. the pitch) of a master disc, simultaneously conserving the available recording space of the disc while preserving the dynamics and fidelity of the recorded material. Five years later, the company introduced automation for this variable pitch feature.
In 1957, Westrex demonstrated the first commercial "45/45" stereo cutter head.
In 1966, Neumann introduced the VMS66, followed by the VMS70 (1970) and the VMS80 (1980), which introduced variable pitch to Neumann's offerings, reducing speed fluctuations to achieve smoother sound and extended dynamic range. Unlike other systems, Neumann's disc cutting system was complete and included the lathe, cutter head, and electronics.
References
External links
Audio Record Magazine: Quick Facts On Disc Recorders (October 1952)
Sound recording technology | Disc cutting lathe | [
"Technology"
] | 676 | [
"Recording devices",
"Sound recording technology"
] |
56,067,306 | https://en.wikipedia.org/wiki/SDS-PAGE | SDS-PAGE (sodium dodecyl sulfate–polyacrylamide gel electrophoresis) is a discontinuous electrophoretic system developed by Ulrich K. Laemmli which is commonly used as a method to separate proteins with molecular masses between 5 and 250 kDa. The combined use of sodium dodecyl sulfate (SDS, also known as sodium lauryl sulfate) and polyacrylamide gel eliminates the influence of structure and charge, and proteins are separated by differences in their size. At least up to 2012, the publication describing it was the most frequently cited paper by a single author, and the second most cited overall.
Properties
SDS-PAGE is an electrophoresis method that allows protein separation by mass. The medium (also referred to as ′matrix′) is a polyacrylamide-based discontinuous gel. The polyacrylamide-gel is typically sandwiched between two glass plates in a slab gel. Although tube gels (in glass cylinders) were used historically, they were rapidly made obsolete with the invention of the more convenient slab gels. In addition, SDS (sodium dodecyl sulfate) is used. About 1.4 grams of SDS bind to a gram of protein, corresponding to one SDS molecule charges per two amino acids. SDS acts as a surfactant, masking the protein's intrinsic charge and conferring them very similar charge-to-mass ratios. The intrinsic charges of the proteins are negligible in comparison to the SDS loading, and the positive charges are also greatly reduced in the basic pH range of a separating gel. Upon application of a constant electric field, the proteins migrate towards the anode, each with a different speed, depending on their mass. This simple procedure allows precise protein separation by mass.
SDS tends to form spherical micelles in aqueous solutions above a certain concentration called the critical micellar concentration (CMC). Above the critical micellar concentration of 7 to 10 millimolar in solutions, the SDS simultaneously occurs as single molecules (monomer) and as micelles, below the CMC SDS occurs only as monomers in aqueous solutions. At the critical micellar concentration, a micelle consists of about 62 SDS molecules. However, only SDS monomers bind to proteins via hydrophobic interactions, whereas the SDS micelles are anionic on the outside and do not adsorb any protein. SDS is amphipathic in nature, which allows it to unfold both polar and nonpolar sections of protein structure. In SDS concentrations above 0.1 millimolar, the unfolding of proteins begins, and above 1 mM, most proteins are denatured. Due to the strong denaturing effect of SDS and the subsequent dissociation of protein complexes, quaternary structures can generally not be determined with SDS. Exceptions are proteins that are stabilised by covalent cross-linking (e.g. -S-S- linkages) and the SDS-resistant protein complexes, which are stable even in the presence of SDS (the latter, however, only at room temperature). To denature the SDS-resistant complexes a high activation energy is required, which is achieved by heating. SDS resistance is based on a metastability of the protein fold. Although the native, fully folded, SDS-resistant protein does not have sufficient stability in the presence of SDS, the chemical equilibrium of denaturation at room temperature occurs slowly. Stable protein complexes are characterised not only by SDS resistance but also by stability against proteases and an increased biological half-life.
Alternatively, polyacrylamide gel electrophoresis can also be performed with the cationic surfactants CTAB in a CTAB-PAGE, or 16-BAC in a BAC-PAGE.
Procedure
The SDS-PAGE method is composed of gel preparation, sample preparation, electrophoresis, protein staining or western blotting and analysis of the generated banding pattern.
Gel production
When using different buffers in the gel (discontinuous gel electrophoresis), the gels are made up to one day prior to electrophoresis, so that the diffusion does not lead to a mixing of the buffers. The gel is produced by free radical polymerization in a mold consisting of two sealed glass plates with spacers between the glass plates. In a typical mini-gel setting, the spacers have a thickness of 0.75 mm or 1.5 mm, which determines the loading capacity of the gel. For pouring the gel solution, the plates are usually clamped in a stand which temporarily seals the otherwise open underside of the glass plates with the two spacers. For the gel solution, acrylamide is mixed as gel-former (usually 4% V/V in the stacking gel and 10-12 % in the separating gel), methylenebisacrylamide as a cross-linker, stacking or separating gel buffer, water and SDS. By adding the catalyst TEMED and the radical initiator ammonium persulfate (APS) the polymerisation is started. The solution is then poured between the glass plates without creating bubbles. Depending on the amount of catalyst and radical starter and depending on the temperature, the polymerisation lasts between a quarter of an hour and several hours. The lower gel (separating gel) is poured first and covered with a few drops of a barely water-soluble alcohol (usually buffer-saturated butanol or isopropanol), which eliminates bubbles from the meniscus and protects the gel solution of the radical scavenger oxygen. After the polymerisation of the separating gel, the alcohol is discarded and the residual alcohol is removed with filter paper. After addition of APS and TEMED to the stacking gel solution, it is poured on top of the solid separation gel. Afterwards, a suitable sample comb is inserted between the glass plates without creating bubbles. The sample comb is carefully pulled out after polymerisation, leaving pockets for the sample application. For later use of proteins for protein sequencing, the gels are often prepared the day before electrophoresis to reduce reactions of unpolymerised acrylamide with cysteines in proteins.
By using a gradient mixer, gradient gels with a gradient of acrylamide (usually from 4 to 12%) can be cast, which have a larger separation range of the molecular masses. Commercial gel systems (so-called pre-cast gels) usually use the buffer substance Bis-tris methane with a pH value between 6.4 and 7.2 both in the stacking gel and in the separating gel. These gels are delivered cast and ready-to-use. Since they use only one buffer (continuous gel electrophoresis) and have a nearly neutral pH, they can be stored for several weeks. The more neutral pH slows the hydrolysis and thus the decomposition of the polyacrylamide. Furthermore, there are fewer acrylamide-modified cysteines in the proteins. Due to the constant pH in collecting and separating gel there is no stacking effect. Proteins in BisTris gels can not be stained with ruthenium complexes. This gel system has a comparatively large separation range, which can be varied by using MES or MOPS in the running buffer.
Sample preparation
During sample preparation, the sample buffer, and thus SDS, is added in excess to the proteins, and the sample is then heated to 95 °C for five minutes, or alternatively 70 °C for ten minutes. Heating disrupts the secondary and tertiary structures of the protein by disrupting hydrogen bonds and stretching the molecules. Optionally, disulfide bridges can be cleaved by reduction. For this purpose, reducing thiols such as β-mercaptoethanol (β-ME, 5% by volume), dithiothreitol (DTT, 10–100 millimolar), dithioerythritol (DTE, 10 millimolar), tris(2-carboxyethyl)phosphine or tributylphosphine are added to the sample buffer. After cooling to room temperature, each sample is pipetted into its own well in the gel, which was previously immersed in electrophoresis buffer in the electrophoresis apparatus.
In addition to the samples, a molecular-weight size marker is usually loaded onto the gel. This consists of proteins of known sizes and thereby allows the estimation (with an error of ± 10%) of the sizes of the proteins in the actual samples, which migrate in parallel in different tracks of the gel. The size marker is often pipetted into the first or last pocket of a gel.
Electrophoresis
For separation, the denatured samples are loaded onto a gel of polyacrylamide, which is placed in an electrophoresis buffer with suitable electrolytes. Thereafter, a voltage (usually around 100 V, 10-20 V per cm gel length) is applied, which causes a migration of negatively charged molecules through the gel in the direction of the positively charged anode. The gel acts like a sieve. Small proteins migrate relatively easily through the mesh of the gel, while larger proteins are more likely to be retained and thereby migrate more slowly through the gel, thereby allowing proteins to be separated by molecular size. The electrophoresis lasts between half an hour to several hours depending on the voltage and length of gel used.
The fastest-migrating proteins (with a molecular weight of less than 5 kDa) form the buffer front together with the anionic components of the electrophoresis buffer, which also migrate through the gel. The area of the buffer front is made visible by adding the comparatively small, anionic dye bromophenol blue to the sample buffer. Due to the relatively small molecule size of bromophenol blue, it migrates faster than proteins. By optical control of the migrating colored band, the electrophoresis can be stopped before the dye and also the samples have completely migrated through the gel and leave it.
The most commonly used method is the discontinuous SDS-PAGE. In this method, the proteins migrate first into a collecting gel with neutral pH, in which they are concentrated and then they migrate into a separating gel with basic pH, in which the actual separation takes place. Stacking and separating gels differ by different pore size (4-6 % T and 10-20 % T), ionic strength and pH values (pH 6.8 or pH 8.8). The electrolyte most frequently used is an SDS-containing Tris-glycine-chloride buffer system. At neutral pH, glycine predominantly forms the zwitterionic form, at high pH the glycines lose positive charges and become predominantly anionic. In the collection gel, the smaller, negatively charged chloride ions migrate in front of the proteins (as leading ions) and the slightly larger, negatively and partially positively charged glycinate ions migrate behind the proteins (as initial trailing ions), whereas in the comparatively basic separating gel both ions migrate in front of the proteins. The pH gradient between the stacking and separation gel buffers leads to a stacking effect at the border of the stacking gel to the separation gel, since the glycinate partially loses its slowing positive charges as the pH increases and then, as the former trailing ion, overtakes the proteins and becomes a leading ion, which causes the bands of the different proteins (visible after a staining) to become narrower and sharper - the stacking effect. For the separation of smaller proteins and peptides, the TRIS-Tricine buffer system of Schägger and von Jagow is used due to the higher spread of the proteins in the range of 0.5 to 50 kDa.
Gel staining
At the end of the electrophoretic separation, all proteins are sorted by size and can then be analyzed by other methods, e. g. protein staining such as Coomassie staining (most common and easy to use), silver staining (highest sensitivity), stains all staining, Amido black 10B staining, Fast green FCF staining, fluorescent stains such as epicocconone stain and SYPRO orange stain, and immunological detection such as the Western Blot. The fluorescent dyes have a comparatively higher linearity between protein quantity and color intensity of about three orders of magnitude above the detection limit (the quantity of protein that can be estimated by color intensity). When using the fluorescent protein dye trichloroethanol, a subsequent protein staining is omitted if it was added to the gel solution and the gel was irradiated with UV light after electrophoresis.
In Coomassie staining, gel is fixed in a 50% ethanol 10% glacial acetic acid solution for 1 hr. Then the solution is changed for fresh one and after 1 to 12 hrs gel is changed to a staining solution (50% methanol, 10% glacial acetic acid, 0.1% coomassie brilliant blue) followed by destaining changing several times a destaining solution of 40% methanol, 10% glacial acetic acid.
Analysis
Protein staining in the gel creates a documentable banding pattern of the various proteins.
Glycoproteins have differential levels of glycosylations and adsorb SDS more unevenly at the glycosylations, resulting in broader and blurred bands.
Membrane proteins, because of their transmembrane domain, are often composed of the more hydrophobic amino acids, have lower solubility in aqueous solutions, tend to bind lipids, and tend to precipitate in aqueous solutions due to hydrophobic effects when sufficient amounts of detergent are not present. This precipitation manifests itself for membrane proteins in a SDS-PAGE in "tailing" above the band of the transmembrane protein. In this case, more SDS can be used (by using more or more concentrated sample buffer) and the amount of protein in the sample application can be reduced.
An overloading of the gel with a soluble protein creates a semicircular band of this protein (e. g. in the marker lane of the image at 66 kDa), allowing other proteins with similar molecular weights to be covered.
A low contrast (as in the marker lane of the image) between bands within a lane indicates either the presence of many proteins (low purity) or, if using purified proteins and a low contrast occurs only below one band, it indicates a proteolytic degradation of the protein, which first causes degradation bands, and after further degradation produces a homogeneous color ("smear") below a band.
The documentation of the banding pattern is usually done by photographing or scanning. For a subsequent recovery of the molecules in individual bands, a gel extraction can be performed.
Archiving
After protein staining and documentation of the banding pattern, the polyacrylamide gel can be dried for archival storage. Proteins can be extracted from it at a later date. The gel is either placed in a drying frame (with or without the use of heat) or in a vacuum dryer. The drying frame consists of two parts, one of which serves as a base for a wet cellophane film to which the gel and a one percent glycerol solution are added. Then a second wet cellophane film is applied bubble-free, the second frame part is put on top and the frame is sealed with clips. The removal of the air bubbles avoids a fragmentation of the gel during drying. The water evaporates through the cellophane film. In contrast to the drying frame, a vacuum dryer generates a vacuum and heats the gel to about 50 °C.
Molecular mass determination
For a more accurate determination of the molecular weight, the relative migration distances of the individual protein bands are measured in the separating gel. The measurements are usually performed in triplicate for increased accuracy. The relative mobility (called Rf value or Rm value) is defined as the distance migrated by the protein band divided by the distance migrated by the buffer front. The distances are each measured from the beginning of the separation gel. The migration of the buffer front roughly corresponds to the migration of the dye contained in the sample buffer. The Rf's of the size marker are plotted semi-logarithmically against their known molecular weights. By comparison with the linear part of the generated graph or by a regression analysis, the molecular weight of an unknown protein can be determined by its relative mobility.
Bands of proteins with glycosylations can be blurred, as glycosylation is often heterogenous. Proteins with many basic amino acids (e. g. histones) can lead to an overestimation of the molecular weight or even not migrate into the gel at all, because they move slower in the electrophoresis due to the positive charges or even to the opposite direction. On the other hand, many acidic amino acids can lead to accelerated migration of a protein and an underestimation of its molecular mass.
Applications
The SDS-PAGE in combination with a protein stain is widely used in biochemistry for the quick and exact separation and subsequent analysis of proteins. It has comparatively low instrument and reagent costs and is an easy-to-use method. Because of its low scalability, it is mostly used for analytical purposes and less for preparative purposes, especially when larger amounts of a protein are to be isolated.
Additionally, SDS-PAGE is used in combination with the western blot for the determination of the presence of a specific protein in a mixture of proteins - or for the analysis of post-translational modifications. Post-translational modifications of proteins can lead to a different relative mobility (i.e. a band shift) or to a change in the binding of a detection antibody used in the western blot (i.e. a band disappears or appears).
In mass spectrometry of proteins, SDS-PAGE is a widely used method for sample preparation prior to spectrometry, mostly using in-gel digestion. In regards to determining the molecular mass of a protein, the SDS-PAGE is a bit more exact than an analytical ultracentrifugation, but less exact than a mass spectrometry or - ignoring post-translational modifications - a calculation of the protein molecular mass from the DNA sequence.
In medical diagnostics, SDS-PAGE is used as part of the HIV test and to evaluate proteinuria. In the HIV test, HIV proteins are separated by SDS-PAGE and subsequently detected by Western Blot with HIV-specific antibodies of the patient, if they are present in his blood serum. SDS-PAGE for proteinuria evaluates the levels of various serum proteins in the urine, e.g. Albumin, Alpha-2-macroglobulin and IgG.
Variants
SDS-PAGE is the most widely used method for gel electrophoretic separation of proteins. Two-dimensional gel electrophoresis sequentially combines isoelectric focusing or BAC-PAGE with a SDS-PAGE. Native PAGE is used if native protein folding is to be maintained. For separation of membrane proteins, BAC-PAGE or CTAB-PAGE may be used as an alternative to SDS-PAGE. For electrophoretic separation of larger protein complexes, agarose gel electrophoresis can be used, e.g. the SDD-AGE. Some enzymes can be detected via their enzyme activity by zymography.
Alternatives
While being one of the more precise and low-cost protein separation and analysis methods, the SDS-PAGE denatures proteins. Where non-denaturing conditions are necessary, proteins are separated by a native PAGE or different chromatographic methods with subsequent photometric quantification, for example affinity chromatography (or even tandem affinity purification), size exclusion chromatography, ion exchange chromatography. Proteins can also be separated by size in a tangential flow filtration or an ultrafiltration. Single proteins can be isolated from a mixture by affinity chromatography or by a pull-down assay. Some historically early and cost effective but crude separation methods usually based upon a series of extractions and precipitations using kosmotropic molecules, for example the ammonium sulfate precipitation and the polyethyleneglycol precipitation.
History
In 1948, Arne Tiselius was awarded the Nobel Prize in Chemistry for the discovery of the principle of electrophoresis as the migration of charged and dissolved atoms or molecules in an electric field. The use of a solid matrix (initially paper discs) in a zone electrophoresis improved the separation. The discontinuous electrophoresis of 1964 by L. Ornstein and B. J. Davis made it possible to improve the separation by the stacking effect. The use of cross-linked polyacrylamide hydrogels, in contrast to the previously used paper discs or starch gels, provided a higher stability of the gel and no microbial decomposition. The denaturing effect of SDS in continuous polyacrylamide gels and the consequent improvement in resolution was first described in 1965 by David F. Summers in the working group of James E. Darnell to separate poliovirus proteins. The current variant of the SDS-PAGE was described in 1970 by Ulrich K. Laemmli and initially used to characterise the proteins in the head of bacteriophage T4.
References
External links
Protocol for BisTris SDS-PAGE at OpenWetWare.org
Electrophoresis | SDS-PAGE | [
"Chemistry",
"Biology"
] | 4,519 | [
"Instrumental analysis",
"Molecular biology techniques",
"Electrophoresis",
"Biochemical separation processes"
] |
56,067,604 | https://en.wikipedia.org/wiki/Higher-order%20operad | In algebra, a higher-order operad is a higher-dimensional generalization of an operad.
See also
Opetope
References
External links
https://ncatlab.org/nlab/show/(infinity%2C1)-operad
Abstract algebra | Higher-order operad | [
"Mathematics"
] | 58 | [
"Abstract algebra",
"Algebra"
] |
56,067,657 | https://en.wikipedia.org/wiki/NIROSETI | The NIROSETI (Near-InfraRed Optical Search for Extraterrestrial Intelligence) is an astronomical program to search for artificial signals in the optical (visible) and near infrared (NIR) wavebands of the electromagnetic spectrum. It is the first dedicated near-infrared SETI experiment. The instrument was created by a collaboration of scientists from the University of California, San Diego, Berkeley SETI Research Center at the University of California, Berkeley, University of Toronto, and the SETI Institute. It uses the Anna Nickel 1-m telescope at the Lick Observatory, situated on the summit of Mount Hamilton, east of San Jose, California, USA. The instrument was commissioned (saw its first light) on 15 March 2015 and has been operated for more than 150 nights, and is still operational today.
Overview
The NIROSETI project is designed to detect infrared pulses. Near-infrared offers a possible way for signal transmission since there is a decrease in both interstellar extinction and Galactic background compared to optical wavelengths. The near-infrared bands remain largely unexplored because instruments capable of capturing short pulses of infrared light have only recently become available.
The NIROSETI instrument makes use of the 1-meter optical Nickel telescope located at the Lick Observatory in California to search for near-infrared (laser) transmissions from extraterrestrial communication or technosignatures. This project was funded by the Bill and Susan Bloomfield Foundation and is based upon a predecessor called Lick Optical SETI instrument, conducted between 2001 and 2006. Professor Shelley Wright leads the team that built and operates the NIROSETI program.
The NIROSETI instrument employs a new generation of near-infrared (900 to 1700 nm) detectors, cooled at -25 °C, that have a high speed response (>1 GHz) and gain comparable to photomultiplier tubes, while also producing very low noise, and significantly reducing false positives. Its field-of-view is 2.5"x2.5" each, and focuses
on detecting short (nanosecond) pulsed laser emissions. The NIROSETI instrument is also being used to study variability of very short natural near-infrared transient stars.
Targets
The NIROSETI survey has been designed for observing several thousand objects over a few years, and commenced full operations on 28 January 2016. During a clear night of observations, about 20 to 30 objects are observed. Because infrared light penetrates farther through gas and dust than visible light, this search will extend to stars thousands of light-years away. The initial target sample is mostly main-sequence and giant stars located within 50 parsecs from Earth, drawn from the Breakthrough Listen program target list.
The sample of targets also includes 82 galaxies for being the nearest representatives of the five major morphological classes of galaxies (20 spirals, 36 ellipticals, 15 dwarf spheroidals, 9 irregulars, and 2 lenticular galaxies), as well as stars that triggered alarms on other targeted SETI surveys.
A significant drawback is that the extraterrestrial laser signals would need to be transmitted in the direction of the Solar System in order to be detected.
See also
Berkeley Open Infrastructure for Network Computing (BOINC)
SETI@home
References
External links
Center for Astrophysics Space Science Optical and Infrared Laboratory
Search for extraterrestrial intelligence
Interstellar messages
University of California, Berkeley
Astrobiology | NIROSETI | [
"Astronomy",
"Biology"
] | 679 | [
"Origin of life",
"Speculative evolution",
"Astrobiology",
"Biological hypotheses",
"Astronomical sub-disciplines"
] |
56,068,490 | https://en.wikipedia.org/wiki/Kosmos%202452 | Kosmos 2452 is a Russian military communications satellite. It was launched July 6, 2009, at 1:26 UTC. It was launched by a Rokot launch vehicle from the Plesetsk Cosmodrome to a 1,400 km circular orbit and a high inclination (~82 degrees).
It was the second Strela 3M satellite and was launched with two other satellites. Strela-3M (also known as Rodnik-S) is an improved version of the Strela-3 military communications satellite.
Satellites of this type record digital information and then forward the stored data when the satellite is in view of a receiving antenna. This approach is used for communications in remote area lacking more traditional ground-based communications channels.
References
Kosmos satellites
Spacecraft launched in 2009
Communications satellites of Russia
2009 in Russia | Kosmos 2452 | [
"Astronomy"
] | 169 | [
"Astronomy stubs",
"Spacecraft stubs"
] |
56,069,261 | https://en.wikipedia.org/wiki/Geeta%20Kashyap%20Vemuganti | Geeta Kashyap Vemuganti (born 1 July 1960) is an Indian ocular pathologist and the head of the department at the Ophthalmic Pathology Service and Stem Cell Laboratory of the L. V. Prasad Eye Institute (LVPEI). She is also a dean and professor at the school of medical sciences of the University of Hyderabad.
Vemuganti is reported to have done pioneering work in stem cell therapy and was a member of the team led by V. S. Sangwan that developed a protocol for transplanting cultured stem cells for restoring vision in humans. She is an elected fellow of the National Academy of Medical Sciences and a recipient of the 2005 Chem Tech Foundation Award. The Department of Biotechnology of the Government of India awarded her the National Bioscience Award for Career Development, one of the highest Indian science awards, for her contributions to biosciences in 2004.
Selected bibliography
See also
Keratitis
Stem cell therapy
Notes
References
Further reading
External links
N-BIOS Prize recipients
Living people
Indian medical academics
All India Institute of Medical Sciences, New Delhi alumni
Academic staff of the University of Hyderabad
Fellows of the National Academy of Medical Sciences
Indian ophthalmologists
Medical doctors from Hyderabad, India
Stem cell researchers
1960 births | Geeta Kashyap Vemuganti | [
"Biology"
] | 258 | [
"Stem cell researchers",
"Stem cell research"
] |
56,069,479 | https://en.wikipedia.org/wiki/Matroid%20parity%20problem | In combinatorial optimization, the matroid parity problem is a problem of finding the largest independent set of paired elements in a matroid. The problem was formulated by as a common generalization of graph matching and matroid intersection. It is also known as polymatroid matching, or the matchoid problem.
Matroid parity can be solved in polynomial time for linear matroids. However, it is NP-hard for certain compactly-represented matroids, and requires more than a polynomial number of steps in the matroid oracle model.
Applications of matroid parity algorithms include finding large planar subgraphs and finding graph embeddings of maximum genus. Matroid parity algorithms can also be used to find connected dominating sets and feedback vertex sets in graphs of maximum degree three.
Formulation
A matroid can be defined from a finite set of elements and from a notion of what it means for subsets of elements to be independent, subject to the following constraints:
Every subset of an independent set should be independent.
If and are independent sets, with , then there exists an element such that is independent.
Examples of matroids include the linear matroids (in which the elements are vectors in a vector space, with linear independence), the graphic matroids (in which the elements are edges in an undirected graph, independent when they contain no cycle), and the partition matroids (in which the elements belong to a family of disjoint sets, and are independent when they contain at most one element in each set). Graphic matroids and partition matroids are special cases of linear matroids.
In the matroid parity problem, the input consists of a matroid together with a pairing on its elements, so that each element belongs to one pair. The goal is to find a subset of the pairs, as large as possible, so that the union of the pairs in the chosen subset is independent. Another seemingly more general variation, in which the allowable pairs form a graph rather than having only one pair per element, is equivalent: an element appearing in more than one pair could be replaced by multiple copies of the element, one per pair.
Algorithms
The matroid parity problem for linear matroids can be solved by a randomized algorithm in time , where is the number of elements of the matroid, is its rank (the size of the largest independent set), and is the exponent in the time bounds for fast matrix multiplication.
In particular, using a matrix multiplication algorithm of Virginia Vassilevska Williams et al., it can be solved in time .
Without using fast matrix multiplication, the linear matroid parity problem can be solved in time . It is also possible to find a minimum-weight solution to the matroid parity problem, or a maximum-weight paired independent set, in linear matroids, in time .
These algorithms are based on a linear algebra formulation of the problem by . Suppose that an input to the problem consists of pairs of -dimensional vectors (arranged as column vectors in a matrix of size ). Then the number of pairs in the optimal solution is
where is a block diagonal matrix whose blocks are submatrices of the form
for a sequence of variables . The Schwartz–Zippel lemma can be used to test whether this matrix has full rank or not (that is, whether the solution has size or not), by assigning random values to the variables and testing whether the resulting matrix has determinant zero. By applying a greedy algorithm that removes pairs one at a time by setting their indeterminates to zero as long as the matrix remains of full rank (maintaining the inverse matrix using the Sherman–Morrison formula to check the rank after each removal), one can find a solution whenever this test shows that it exists. Additional methods extend this algorithm to the case that the optimal solution to the matroid parity problem has fewer than pairs.
For graphic matroids, more efficient matroid parity algorithms are known, based on range searching data structures, with running time on graphs with vertices and edges.
For simple graphs, is , but for multigraphs, it may be larger, so it is also of interest to have algorithms with smaller or no dependence on and worse dependence on . In these cases, it is also possible to solve the graphic matroid parity problem in randomized expected time , or in time when each pair of edges forms a path.
Although the matroid parity problem is NP-hard for arbitrary matroids, it can still be approximated efficiently. Simple local search algorithms provide a polynomial-time approximation scheme for this problem, and find solutions whose size, as a fraction of the optimal solution size, is arbitrarily close to one. The algorithm starts with the empty set as its solution, and repeatedly attempts to increase the solution size by one by removing at most a constant number of pairs from the solution and replacing them by a different set with one more pair. When no more such moves are possible, the resulting solution is returned as the approximation to the optimal solution. To achieve an approximation ratio of , it suffices to choose to be approximately .
Applications
Many other optimization problems can be formulated as linear matroid parity problems, and solved in polynomial time using this formulation.
Hardness
The clique problem, of finding a -vertex complete subgraph in a given -vertex graph , can be transformed into an instance of matroid parity as follows.
Construct a paving matroid on elements, paired up so that there is one pair of elements per pair of vertices. Define a subset of these elements to be independent if it satisfies any one of the following three conditions:
has fewer than elements.
has exactly elements, but is not the union of pairs of elements.
is the union of pairs of elements that form a clique in .
Then there is a solution to the matroid parity problem for this matroid, of size , if and only if has a clique of size . Since finding cliques of a given size is NP-complete, it follows that determining whether this type of matrix parity problem has a solution of size is also NP-complete.
This problem transformation does not depend on the structure of the clique problem in any deep way, and would work for any other problem of finding size- subsets of a larger set that satisfy a computable test. By applying it to a randomly-permuted graph that contains exactly one clique of size , and applying Yao's principle relating expected and average-case complexity, one can show that any deterministic or randomized algorithm for matroid parity that accesses its matroid only by independence tests needs to make an exponential number of tests.
References
Combinatorial optimization
Intersection | Matroid parity problem | [
"Mathematics"
] | 1,367 | [
"Matroid theory",
"Combinatorics"
] |
56,070,044 | https://en.wikipedia.org/wiki/Russell%20Varian%20Prize | The Russell Varian Prize was an international scientific prize awarded for a single, high-impact and innovative contribution in the field of nuclear magnetic resonance (NMR), that laid the foundation for the development of new technologies in the field. It honored the memory of Russell Varian, the pioneer behind the creation of the first commercial NMR spectrometer and the co-founder, in 1948, of Varian Associates, one of the first high-tech companies in Silicon Valley. The prize carried a monetary award of €15,000 and it was awarded annually between the years 2002 and 2015 (except for 2003) by a committee of experts in the field. The award ceremony alternated between the European Magnetic Resonance (EUROMAR) Conference and the International Council on Magnetic Resonance in Biological Systems (ICMRBS) Conference. Originally, the prize was sponsored by Varian, Inc. and later by Agilent Technologies, after the latter acquired Varian, Inc. in 2010. The prize was discontinued in 2016 after Agilent Technologies closed its NMR division.
Russell Varian Prize Awardees
2002 Jean Jeener. Contribution: Multi-dimensional Fourier NMR spectroscopy.
2004 Erwin L. Hahn. Contribution: Spin echo phenomena and experiments.
2005 Nicolaas Bloembergen. Contribution: Nuclear magnetic relaxation.
2006 John S. Waugh. Contribution: Average Hamiltonian theory.
2007 Alfred G. Redfield. Contribution: Relaxation Theory.
2008 Alexander Pines. Contribution: Cross-polarization method for NMR in solids.
2009 Albert W. Overhauser. Contribution: Nuclear Overhauser effect (NOE).
2010 Martin Karplus. Contribution: Karplus equation.
2011 Gareth A. Morris. Contribution: INEPT pulse sequence.
2012 Ray Freeman and Weston A. Anderson. Contribution: Double resonance.
2013 Lucio Frydman. Contribution: Ultrafast NMR.
2014 Ad Bax. Contribution: Homonuclear broad band decoupled absorption spectra.
2015 Malcolm Levitt. Contribution: Composite pulses.
See also
List of physics awards
References
Science and technology awards
Physics awards
Nuclear magnetic resonance
Awards established in 2002
Awards disestablished in 2016 | Russell Varian Prize | [
"Physics",
"Chemistry",
"Technology"
] | 434 | [
"Science and technology awards",
"Nuclear magnetic resonance",
"Physics awards",
"Nuclear physics"
] |
56,071,157 | https://en.wikipedia.org/wiki/V8%20medium | V8 medium is a kind of agar medium which is used to cultivate the spore of Phytophthora sojae. Phytophthora sojae causes soybean blight (Phytophthora root rot of soybeans). Soybean blight can affect the output and quality of soybeans seriously. The spore of phytophthora sojae is difficult to culture in potato dextrose agar; it is generally cultured by V8 medium and lima bean agar at home and abroad. V8 medium can cultivate, separate, reproduce and conserve many kinds spore of phytophthora sojae, but it is not suitable for cultivating the pathogen of potato late blight.
References
Sinclair, J.B.; Dhingra, O.D. (1995). Basic Plant Pathology Methods. Taylor & Francis. p. 36. .
Santamaria, L. (2007). Evaluation of Lima Bean (Phaseolus Lunatus) Germplasm for Resistance to Downy Mildew, and Epidemiological and Biological Studies of Its Causal Agent, Phytophthora Phaseoli. University of Delaware. pp. 39–40. .
Cell culture media
Microbiological media | V8 medium | [
"Biology"
] | 265 | [
"Microbiological media",
"Microbiology equipment"
] |
56,071,248 | https://en.wikipedia.org/wiki/Krtin%20Nithiyanandam | Krtin Nithiyanandam is a British medical researcher. He was awarded the Scientific American Innovator Award at the 2015 Google Science Fair for his work on developing a novel diagnosis test for early-onset Alzheimer's disease. The award came with $25,000. In 2017, Krtin's research on identifying a mechanism to make triple-negative breast cancer more treatable won the Intermediate Science stream at the national Big Bang Fair. Recently, Nithiyanandam was the recipient of the U.K. Junior Water Prize for his project titled "A novel, photocatalytic, lead-sequestering bioplastic for sustainable water purification and environmental remediation". He represented the U.K. at the international Stockholm Junior Water Prize.
In 2017, Nithiyanandam was named as a Rising Star in Science by The Observer and as one of TIME's 30 Most Influential Teens of 2017. Krtin currently attends Stanford University.
Biography
Krtin Nithiyanandam was born in Chennai, India and moved to Britain with his family. Nithiyanandam's interest in the medical sciences started after he suffered from hearing impairment as a child. He studied at Sutton Grammar School. Nithiyanandam has explained his research at TEDxLondon, TEDxGateway, WIRED: Next Generation, and the Royal Society of Medicine, and has advocated for increased student participation in scientific research. Krtin is a member of Stanford University's Class of 2022.
Research
Alzheimer's research
Nithiyanandam's work focused on oligomeric amyloid beta as a biomarker for Alzheimer's disease instead of amyloid beta plaques. Nithiyanandam developed a bispecific antibody composed of two different Fab' fragments: one fragment from an anti-oligomeric amyloid beta IgG molecule and another fragment from an anti-transferrin receptor IgM molecule. Nithiyanandam's bispecific antibody is conjugated to a quantum dot with MRI and fNIR detection capabilities. Nithiyanandam's in vitro studies suggest that the bispecific antibody quantum dot conjugate has little cross-reactivity and could potentially cross the blood-brain barrier. He won the Scientific American Innovator Award at the Google Science Fair for this work.
Cancer research
Nithiyanandam's research sought to develop a novel siRNA mechanism to decrease ID4 expression in aggressive triple-negative breast cancers. Nithiyanandam found that a knockdown in ID4 expression resulted in aggressive triple-negative breast cancers developing primitive oestrogen receptors on their surface, consequently making the cancer susceptible to existing breast-cancer treatments. Moreover, Nithiyanandam found that increasing PTEN expression in several breast cancer cells lines, including MCF-7, resulted in increased chemosensitivity to cisplatin. However, increased PTEN expression in "healthy cell line" MCF10A resulted in decreased chemosensitivity to cisplatin. He was the winner of the Intermediate stream of the Big Bang Fair for his work.
Bioplastic research
Nithiyanandam developed a novel bioplastic capable of sequestering lead and purifying water through photocatalysis. CIWEM, the organisation that awards the U.K. Junior Water Prize, commented that Nithiyanandam's project focused "on meeting global wastewater management challenges, and exhibits wastewater as an opportunity rather than a waste product".
References
Living people
Scientists from Chennai
2000 births
People educated at Sutton Grammar School
21st-century British inventors
Alzheimer's disease researchers
British cancer researchers
Environmental research
Indian emigrants to the United Kingdom | Krtin Nithiyanandam | [
"Environmental_science"
] | 767 | [
"Environmental research"
] |
56,071,996 | https://en.wikipedia.org/wiki/List%20of%20investigational%20antipsychotics | This is a list of investigational antipsychotics, or antipsychotics that are currently under development for clinical use but are not yet approved. Chemical/generic names are listed first, with developmental code names, synonyms, and brand names in parentheses.
This list was last comprehensively updated in December 2017. It is likely to become outdated with time.
Receptor modulators
Monoamine receptor modulators
Brilaroxazine (RP5063; oxaripiprazole) – atypical antipsychotic (D2/3/4 and 5-HT1A partial agonist and 5-HT2A/2B/7 antagonist)
FKF-02SC (TGOF-02N) – atypical antipsychotic (D2 and 5-HT2A receptor antagonist, other actions)
Masupirdine (SUVN-502) – 5-HT6 receptor antagonist
N-Methylamisulpride (LB-102) – D2,3, 5-HT7, receptor antagonist (methylated version of amisulpride)
Ralmitaront (RG-7906, RO-6889450) – TAAR1 agonist
Ulotaront (SEP-856, SEP-363856) – 5-HT1A receptor and TAAR1 agonist
Usmarapride (SUVN-D4010) – 5-HT4 receptor partial agonist
Glutamate receptor modulators
Pomaglumetad methionil (DB-103, LY-2140023, LY-2812223) – mGluR2 and mGluR3 agonist
Iclepertin – glycine transporter-1 inhibitor
Acetylcholine receptor modulators
Emraclidine (CVL-231) – M4 muscarinic acetylcholine receptor positive allosteric modulator.
ML-007 – M1 and M4 muscarinic acetylcholine receptor agonist.
NBI-1117568 (HTL 0016878) – M4 muscarinic acetylcholine receptor agonist.
NS-136 – M4 muscarinic acetylcholine receptor positive allosteric modulator
Cannabinoid receptor modulators
Cannabidiol (CBD; GW-42003, GWP-42003, GWP-42003-P, ECP-012A; Arvisol, Epidiolex) – cannabinoid receptor modulator, antioxidant, other actions
Other/mixed receptor modulators
CVN766 – Orexin receptor type 1 antagonist
Deudextromethorphan (d-DM; AVP-786, CTP-786) – σ1 receptor agonist, serotonin–norepinephrine reuptake inhibitor, uncompetitive NMDA receptor antagonist, muscarinic acetylcholine receptor agonist, other actions
Roluperidone (CYR-101, MIN-101, MT-210) – 5-HT2A and σ2 receptor antagonist
TAK-041 (NBI 1065846) – GPR139 receptor agonist
Enzyme inhibitors
Luvadaxistat (NBI 1065844, TAK-831) – D-amino acid oxidase inhibitor. (DAAO is a pathway to NMDAR.)
MK-8189 – phosphodiesterase 10A inhibitor.
Osoresnontrine (BI-409306, SUB-166499) – phosphodiesterase 9A inhibitor
Sodium benzoate (SND-11, SND-12, SND-13, SND-14; Clozaben, NaBen) – D-amino acid oxidase inhibitor
Ion channel modulators
Evenamide (NW-3509; NW-3509A) – Nav1.3, Nav1.7, and Nav1.8 voltage-gated sodium channel blocker
Others
TS-134 (TS-1341) – undefined mechanism of action
Kratom – Has shown antipsychotic-like effects on par with haloperidol in animal testing
See also
List of investigational drugs
References
External links
AdisInsight – Springer
2016 Medicines in Development for Mental Health – PhRMA
Antipsychotics
Antipsychotics, investigational
Dynamic lists
Experimental psychiatric drugs | List of investigational antipsychotics | [
"Chemistry"
] | 956 | [
"Drug-related lists"
] |
56,072,231 | https://en.wikipedia.org/wiki/Petcube | Petcube is a technology company that designs and develops smart devices for pets which combine cameras with treat dispensers and laser pointer toys.
History
The company was founded in 2012 in Kyiv, Ukraine by Alex Neskin, Yaroslav Azhnyuk, and Andrey Klen. Typically for a startup, Petcube aimed to solve the problem the founders faced on their own: Neskin's dog Rocky suffered and misbehaved due to separation anxiety.
Within two Kickstarter campaigns the project raised $250,000 in 2013 (becoming the best funded pet product by that time) and $315,000 in 2016. In 2017, Petcube announced a treat partnership with Wellness and acquised a Canadian pet-focused startup Petbot. In the following years, Petcube raised over $14 million in seed money and Series A financing from Y Combinator, Almaz Capital, Aventures, and other investors.
Products
Petcube offers three devices: Petcube Camera, Petcube Bites with camera and a treat dispenser, and Petcube Play which features a laser pointer to keep the pet entertained (distracted) while the owner is away.
The devices can stream and record video, toss treats, allow users to communicate with a pet two-way, and connect to Amazon Alexa. Paid subscription enables cloud video storage, automated recording triggered by sound or motion, smart alerts (bark, meow, pet, and human notifications), and adds a web interface.
Charity
Petcube cooperates with shelters and helps to save pets and find them new homes. The company donates its products and organize events for pet activists. As a Ukrainian brand, Petcube joined United24 charity project and donates proceeds from its pet cameras to the future rebuilding of Ukraine.
References
Manufacturing companies established in 2013
Companies based in San Francisco
Technology companies established in 2013
Cameras
Kickstarter-funded products | Petcube | [
"Technology"
] | 393 | [
"Recording devices",
"Cameras"
] |
56,072,400 | https://en.wikipedia.org/wiki/Spin%20squeezing | Spin squeezing is a quantum process that decreases the variance of one of the angular momentum components in an ensemble of particles with a spin. The quantum states obtained are called spin squeezed states. Such states have been proposed for quantum metrology, to allow a better precision for estimating a rotation angle than classical interferometers. However a wide body of work contradicts this analysis. In particular, these works show that the estimation precision obtainable for any quantum state can be expressed solely in terms of the state response to the signal. As squeezing does not increase the state response to the signal, it cannot fundamentally improve the measurement precision.
Mathematical definition
Spin squeezed states for an ensemble of spins have been defined analogously to squeezed states of a bosonic mode. For any quantum state (not necessarily a pure state), let be the direction of its mean spin, so that . By the Heisenberg uncertainty relation,where are the collective angular momentum components defined as and are the single particle angular momentum components.
We say that the state is spin-squeezed in the -direction, if the variance of the -component is smaller than the square root of the right-hand side of the inequality aboveA different definition was based on using states with a reduced spin-variance for metrology.
Relations to quantum entanglement
Spin squeezed states can be proven to be entangled based on measuring the spin length and the variance of the spin in an orthogonal direction. Let us define the spin squeezing parameter
,
where is the number of the spin- particles in the ensemble. Then, if is smaller than then the state is entangled. It has also been shown that a higher and higher level of multipartite entanglement is needed to achieve a larger and larger degree of spin squeezing.
Experiments with atomic ensembles
Experiments have been carried out with cold or even room temperature atomic ensembles. In this case, the atoms do not interact with each other. Hence, in order to entangle them, they make them interact with light which is then measured. A 20 dB (100 times) spin squeezing has been obtained in such a system. Simultaneous spin squeezing of two ensembles, which interact with the same light field, has been used to entangle the two ensembles. Spin squeezing can be enhanced by using cavities.
Cold gas experiments have also been carried out with Bose-Einstein Condensates (BEC). In this case, the spin squeezing is due to the interaction between the atoms.
Most experiments have been carried out using only two internal states of the particles, hence, effectively with spin- particles. There are also experiments aiming at spin squeezing with particles of a higher spin. Nuclear-electron spin squeezing within the atoms, rather than interatomic spin squeezing, has also been created in room temperature gases.
Creating large spin squeezing
Experiments with atomic ensembles are usually implemented in free-space with Gaussian laser beams. To enhance the spin squeezing effect towards generating non-Gaussian states, which are metrologically useful, the free-space apparatuses are not enough. Cavities and nanophotonic waveguides have been used to enhance the squeezing effect with less atoms.
For the waveguide systems, the atom-light coupling and the squeezing effect can be enhanced using the evanescent field near to the waveguides, and the type of atom-light interaction can be controlled by choosing a proper polarization state of the guided input light, the internal state subspace of the atoms and the geometry of the trapping shape. Spin squeezing protocols using nanophotonic waveguides based on the birefringence effect and the Faraday effect have been proposed. By optimizing the optical depth or cooperativity through controlling the geometric factors mentioned above, the Faraday protocol demonstrates that, to enhance the squeezing effect, one needs to find a geometry that generates weaker local electric field at the atom positions. This is counterintuitive, because usually to enhance atom-light coupling, a strong local field is required. But it opens the door to perform very precise measurement with little disruptions to the quantum system, which cannot be simultaneously satisfied with a strong field.
Generalized spin squeezing
In entanglement theory, generalized spin squeezing also refers to any criterion that is given with the first and second moments of angular momentum coordinates, and detects entanglement in a quantum state. For a large ensemble of spin-1/2 particles a complete set of such relations have been found, which have been generalized to particles with an arbitrary spin. Apart from detecting entanglement in general, there are relations that detect multipartite entanglement. Some of the generalized spin-squeezing entanglement criteria have also a relation to quantum metrological tasks. For instance, planar squeezed states can be used to measure an unknown rotation angle optimally.
References
Quantum information science
Quantum optics | Spin squeezing | [
"Physics"
] | 978 | [
"Quantum optics",
"Quantum mechanics"
] |
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