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49,155,297 | https://en.wikipedia.org/wiki/Calder%C3%B3n%20projector | In applied mathematics, the Calderón projector is a pseudo-differential operator used widely in boundary element methods. It is named after Alberto Calderón.
Definition
The interior Calderón projector is defined to be:
where is almost everywhere, is the identity boundary operator, is the double layer boundary operator, is the single layer boundary operator, is the adjoint double layer boundary operator and is the hypersingular boundary operator.
The exterior Calderón projector is defined to be:
References
Potential theory
Partial differential equations
Complex analysis
Operator theory
Numerical analysis | Calderón projector | [
"Mathematics"
] | 106 | [
"Functions and mappings",
"Computational mathematics",
"Mathematical objects",
"Potential theory",
"Mathematical relations",
"Numerical analysis",
"Approximations"
] |
49,155,519 | https://en.wikipedia.org/wiki/Itruvone | Itruvone (; developmental code name PH10), also known as pregn-4-en-20-yn-3-one, is a vomeropherine which is under development by VistaGen Therapeutics as a nasal spray for the treatment of major depressive disorder.
See also
List of investigational antidepressants
List of neurosteroids § Pheromones and pherines
References
Ethynyl compounds
Experimental antidepressants
Ketones
Pregnanes | Itruvone | [
"Chemistry"
] | 104 | [
"Ketones",
"Functional groups"
] |
49,155,874 | https://en.wikipedia.org/wiki/LY-2459989 | LY-2459989 is a silent antagonist of the κ-opioid receptor (KOR) that has been developed by Eli Lilly as a radiotracer of that receptor, labeled either with carbon-11 or fluorine-18. It possesses high affinity for the KOR (Ki = 0.18 nM) and is highly selective for it over the μ-opioid receptor (Ki = 7.68 nM) and the δ-opioid receptor (Ki = 91.3 nM) (over 43-fold selectivity for the KOR over the other opioid receptors). LY-2459989 is a fluorine-containing analogue and follow-up compound of LY-2795050, the first KOR-selective antagonist radiotracer. Relative to LY-2795050, LY-2459989 displays 4-fold higher affinity for the KOR and similar selectivity and also possesses greatly improved central nervous system permeation (brain levels were found to be 6-fold higher than those of LY-2795050). The drug appears to possess a short duration of action, with only 25% remaining in serum at 30 minutes post-injection in rhesus monkeys, making it an ideal agent for application in biomedical imaging, for instance in positron emission tomography (PET).
Earlier analogues of LY-2459989 besides LY-2795050 with similar actions and potential uses have also been described.
See also
κ-Opioid receptor § Antagonists
List of investigational antidepressants
References
Benzamides
Kappa-opioid receptor antagonists
Fluoroarenes
3-Pyridyl compounds
Pyrrolidines
Radiopharmaceuticals
Synthetic opioids
Experimental antidepressants | LY-2459989 | [
"Chemistry"
] | 380 | [
"Chemicals in medicine",
"Radiopharmaceuticals",
"Medicinal radiochemistry"
] |
49,156,968 | https://en.wikipedia.org/wiki/Endocannabinoid%20enhancer | An endocannabinoid enhancer (eCBE) is a type of cannabinoidergic drug that enhances the activity of the endocannabinoid system by increasing extracellular concentrations of endocannabinoids. Examples of different types of eCBEs include fatty acid amide hydrolase (FAAH) inhibitors, monoacylglycerol lipase (MAGL) inhibitors, and endocannabinoid transporter (eCBT) inhibitors (or "endocannabinoid reuptake inhibitors" ("eCBRIs")). An example of an actual eCBE is AM404, the active metabolite of the analgesic paracetamol (acetaminophen; Tylenol) and a dual FAAH inhibitor and eCBRI.
See also
Cannabinoid receptor
Synthetic cannabinoid
Cannabinoid receptor antagonist
References
Endocannabinoids | Endocannabinoid enhancer | [
"Chemistry"
] | 189 | [
"Pharmacology",
"Pharmacology stubs",
"Medicinal chemistry stubs"
] |
49,157,683 | https://en.wikipedia.org/wiki/Sarcodon%20bubalinus | Sarcodon bubalinus is a European species of tooth fungus in the family Bankeraceae. First described by Christian Hendrik Persoon in 1825 as Hydnum bubalinum, it was transferred to the genus Sarcodon by Rudolph Arnold Maas Geesteranus in 1956.
References
External links
Fungi described in 1825
Fungi of Europe
bubalinus
Taxa named by Christiaan Hendrik Persoon
Fungus species | Sarcodon bubalinus | [
"Biology"
] | 86 | [
"Fungi",
"Fungus species"
] |
49,157,777 | https://en.wikipedia.org/wiki/Sarcodon%20quietus | Sarcodon quietus is a species of tooth fungus in the family Bankeraceae. Found in the Congo, it was described as new to science in 1967 by Dutch mycologist Rudolph Arnold Maas Geesteranus.
References
External links
Fungi described in 1967
Fungi of Africa
quietus
Fungus species | Sarcodon quietus | [
"Biology"
] | 60 | [
"Fungi",
"Fungus species"
] |
49,157,833 | https://en.wikipedia.org/wiki/Sarcodon%20procerus | Sarcodon procerus is a species of tooth fungus in the family Bankeraceae. Found in the Democratic Republic of the Congo, it was described as new to science in 1967 by Dutch mycologist Rudolph Arnold Maas Geesteranus. Its spores measure 6.7–8 by 4.5–5.4 μm.
References
External links
Fungi described in 1967
Fungi of Africa
procerus
Fungus species | Sarcodon procerus | [
"Biology"
] | 85 | [
"Fungi",
"Fungus species"
] |
49,157,905 | https://en.wikipedia.org/wiki/Sarcodon%20praestans | Sarcodon praestans is a species of tooth fungus in the family Bankeraceae. Found in Papua New Guinea, it was described as new to science in 1974 by Dutch mycologist Rudolph Arnold Maas Geesteranus.
References
External links
Fungi described in 1974
Fungi of New Guinea
praestans
Fungus species | Sarcodon praestans | [
"Biology"
] | 66 | [
"Fungi",
"Fungus species"
] |
49,157,968 | https://en.wikipedia.org/wiki/Sarcodon%20illudens | Sarcodon illudens is a species of tooth fungus in the family Bankeraceae. It was described in 1976 by Dutch mycologist Rudolph Arnold Maas Geesteranus, from collections made in France.
References
External links
Fungi described in 1976
Fungi of Europe
illudens
Fungus species | Sarcodon illudens | [
"Biology"
] | 59 | [
"Fungi",
"Fungus species"
] |
49,158,025 | https://en.wikipedia.org/wiki/Sarcodon%20ianthinus | Sarcodon ianthinus is a species of tooth fungus in the family Bankeraceae. Found in Papua New Guinea, it was described as new to science in 1974 by Dutch mycologist Rudolph Arnold Maas Geesteranus.
References
External links
Fungi described in 1974
Fungi of New Guinea
ianthinus
Fungus species | Sarcodon ianthinus | [
"Biology"
] | 64 | [
"Fungi",
"Fungus species"
] |
49,158,055 | https://en.wikipedia.org/wiki/Sulfide%20intrusion | In ecology, sulfide intrusion refers to an excess of sulfide molecules (S2-) in the soil that interfere with plant growth, often seagrass.
Seagrass bed sediment (soil) is typically anoxic, containing a reduced form of sulfur: hydrogen sulfide (H2S). H2S is a phytotoxin that results from anaerobic digestion, the decomposition of organic matter in the absence of oxygen. However, seagrass can persist in this environment because of physiological adaptations, as well as functional adaptations of other organisms in the ecosystem. For example, bivalves (clams) in the family Lucinidae host symbiotic bacteria that oxidize sulfides. Lucinid bivalves' gills house the bacteria, and the siphon supplies the bacteria and surrounding pore water with oxygenated water from above the sediment. Bacterial oxidation of the sulfides results in sulfates, reducing toxicity.
See also
Nutrient cycle
Redox
Sulfur cycle
Soil chemistry
Soil biology
Environmental microbiology
Microbial biodegradation
References
Ecology
Sulfur
Soil chemistry | Sulfide intrusion | [
"Chemistry",
"Biology"
] | 222 | [
"Soil chemistry",
"Ecology"
] |
49,158,070 | https://en.wikipedia.org/wiki/Sarcodon%20humilis | Sarcodon humilis is a species of tooth fungus in the family Bankeraceae. Found in Malaysia, it was described as new to science in 1971 by Dutch mycologist Rudolph Arnold Maas Geesteranus.
References
External links
Fungi described in 1971
Fungi of Asia
humilis
Fungus species | Sarcodon humilis | [
"Biology"
] | 59 | [
"Fungi",
"Fungus species"
] |
49,158,131 | https://en.wikipedia.org/wiki/Sarcodon%20harrisonii | Sarcodon harrisonii is a species of tooth fungus in the family Bankeraceae. Found in the southeastern United States, it was described as new to science in 1985 by Richard Baird. The type collection was made near Asheville, North Carolina. The fruit body has a flattened cap up to wide with a leathery surface texture that is reddish brown to dark brown. Spores are more or less spherical, measuring 7–8 by 6–7.5 μm. S. harrisonii is similar in appearance to the Michigan species S. ustalis. The specific epithet honors Canadian mycologist Kenneth A. Harrison for his work on stipitate hydnums.
References
External links
Fungi described in 1985
Fungi of the United States
harrisonii
Fungi without expected TNC conservation status
Fungus species | Sarcodon harrisonii | [
"Biology"
] | 160 | [
"Fungi",
"Fungus species"
] |
49,158,204 | https://en.wikipedia.org/wiki/Sarcodon%20dissimulans | Sarcodon dissimulans is a species of tooth fungus in the family Bankeraceae. Found in Nova Scotia, Canada, it was described as new to science in 1984 by mycologist Kenneth A. Harrison. It is characterized as having an "extremely nauseating" taste. Its spores are roughly spherical to oblong, measuring 5–6 by 4–5 μm.
References
External links
Fungi described in 1984
Fungi of Canada
dissimulans
Fungi without expected TNC conservation status
Fungus species | Sarcodon dissimulans | [
"Biology"
] | 104 | [
"Fungi",
"Fungus species"
] |
49,158,244 | https://en.wikipedia.org/wiki/Hydnellum%20lepidum | Hydnellum lepidum is a species of tooth fungus in the family Bankeraceae. Found in Europe, it was described as new to science in 1975 by Dutch mycologist Rudolph Arnold Maas Geesteranus.
References
External links
Fungi described in 1975
Fungi of Europe
lepidum
Fungus species | Hydnellum lepidum | [
"Biology"
] | 62 | [
"Fungi",
"Fungus species"
] |
49,158,253 | https://en.wikipedia.org/wiki/Thonny | Thonny ( ) is a free and open-source integrated development environment for Python that is designed for beginners. It was created by Aivar Annamaa, an Estonian programmer. It supports different ways of stepping through code, step-by-step expression evaluation, detailed visualization of the call stack and a mode for explaining the concepts of references and heap.
Features
Line numbers
Statement stepping without breakpoints
Live variables during debugging
Stepping through evaluation of the expressions (expressions get replaced by their values)
Separate windows for executing function calls (for explaining local variables and call stack)
Variables and memory can be explained either by using simplified model (name → value) or by using more realistic model (name → address/id → value)
Simple pip GUI
Support for CPython and MicroPython
Support for running and managing files on a remote machine via SSH
Possibility to log user actions for replaying or analyzing the programming process
Availability
The program works on Windows, macOS and Linux. It is available as a binary bundle including the recent Python interpreter or pip-installable package. It can be installed via the operating-system package manager on Debian, Raspberry Pi, Ubuntu, and Fedora.
Reception
Thonny has received favorable reviews from Python and computer science education communities.
It has been a recommended tool in several programming MOOCs.
Since June 2017 it has been included by default in the Raspberry Pi's official operating system distribution Raspberry Pi OS.
See also
List of integrated development environments for Python programming language
Toolbox
Kojo
JUDO
BASIC-256
Microsoft Small Basic
References
External links
Development site
Computer science education
Free integrated development environments for Python
Pedagogic integrated development environments
Python (programming language) software
Software using the MIT license | Thonny | [
"Technology"
] | 359 | [
"Computer science education",
"Computer science"
] |
49,158,311 | https://en.wikipedia.org/wiki/Liulin%20type%20instruments | Liulin-type is a class of spectrometry-dosimetry instruments. The instruments are specific types of semiconductor-based ionizing radiation sensors that are capable of measuring the deposited energy of the particle in silicon PIN diode and also the flux of particles. The measured data output is then a time series of spectral intensity. The data about mixed field radiation (usually the secondary cosmic rays) is then used to calculate radiation dose relevant to the specific mission e.g. for a crew or aerospace equipment.
The main advantages of this type of ionizing radiation detector compared to classical setups with scintillators are a significant reduction in weight, and size together with extremely low power consumption.
History
The first Liulin device was developed in 1986–1988 time period for the scientific program of the second Bulgarian cosmonaut for the flight on MIR space station. After the MIR station deorbit similar experiments with revised versions of detectors continue on ISS.
Since the beginning of 2015, open-source hardware detectors based on the same technology called SPACEDOS have been developed. Then the SPACEDOS instruments in different variants are used on board ISS parallel to Liulin dosimeters.
Principle of function
All Liulin type dosimetric instruments use one or more silicon detectors and measure the deposited energy and number of particles in the period into the detector(s) when especially the charged particles hit the device, the semiconductor material is ionized and the charge is measured allowing to calculate the dose rate and particle flux.
In detail, the signal processing in the original LIULIN instrument was based on a single silicon PIN diode followed by a charge-sensitive shaping amplifier (CSA). The number of pulses at the output of CSA above a given threshold was proportional to the particle flux hitting the detector; the amplitude of the pulses at the output of CSA was proportional to the energy deposited by particles. Further the integral of the energy depositions of the particles accumulated in the detector during the measurement interval allowed calculation of the dose rate.
The original concept has a significant drawback in poor repeatability of original LIULIN instruments because the peak detection threshold was set by a mechanical trimmer, which was sensitive to initial setup and vibrations during usage.
That situation resulted in the design of multiple open-source Liulin-equivalent instruments developed in the Czech Republic called AIRDOS and SPACEDOS, where the given energy threshold is replaced by the invention of a new type of peak detector with analog memory. The improved signal processing circuit improves multiple parameters not only the issue with different energy threshold of different Liulin detector pieces, but at the same time allows to detection of deposited energies down to noise of detector itself.
Use cases
The main usage of the described semiconductor detector type is in cosmic ray dosimetry. There exist multiple variants of Liulin-type detectors which extend its use cases to airliner dosimetry.
For example, there exists a variant of open-source hardware AIRDOS instruments specially designed for multiple types of UAVs.
References
Scientific instruments
Space program of Bulgaria
Interkosmos program | Liulin type instruments | [
"Technology",
"Engineering"
] | 609 | [
"Scientific instruments",
"Measuring instruments"
] |
49,158,860 | https://en.wikipedia.org/wiki/Discontinuous%20electrophoresis | Discontinuous electrophoresis (colloquially disc electrophoresis) is a type of polyacrylamide gel electrophoresis. It was developed by Ornstein and Davis. This method produces high resolution and good band definition. It is widely used technique for separating proteins according to size and charge.
Method
In this method, the gel is divided into two discontinuous parts, resolving and stacking gel, both have different concentrations of polyacrylamide. The one with lower concentration is stacked on top of the one with higher concentration. Discontinuity is based on four parameters: gel structure, pH value of the buffer, ionic strength of the buffer, and the nature of the ions in the gel and electrode buffer. The electrode buffer contains glycine. Glycine has very low net charge at pH 6.8 of stacking gel, so it has low mobility. The proteins are separated according to the principle of isotachophoresis and form stacks in the order of mobility (stacking effect). Mobility depends on net charge, not on the size of the molecule. Proteins move towards anode slowly at constant speed till they reach limit of separation gel. Suddenly, frictional resistance increases but glycine is not affected and it passes the proteins and becomes highly charged in resolving zone. Proteins present in homogeneous buffer start to separate based on principles of zone electrophoresis. Now their mobility depends on size as well as charge. pH value rises to 9.5 and net charge increases.
See also
Affinity electrophoresis
SDS-PAGE
Isotachophoresis
References
External links
Analysis of C14-labeled proteins by disc electrophoresis
Electrophoresis | Discontinuous electrophoresis | [
"Chemistry",
"Biology"
] | 350 | [
"Instrumental analysis",
"Molecular biology techniques",
"Electrophoresis",
"Biochemical separation processes"
] |
49,159,269 | https://en.wikipedia.org/wiki/APC%20Family | The Amino Acid-Polyamine-Organocation (APC) Family (TC# 2.A.3) of transport proteins includes members that function as solute:cation symporters and solute:solute antiporters. They occur in bacteria, archaea, fungi, unicellular eukaryotic protists, slime molds, plants and animals. They vary in length, being as small as 350 residues and as large as 850 residues. The smaller proteins are generally of prokaryotic origin while the larger ones are of eukaryotic origin. Most of them possess twelve transmembrane α-helical spanners but have a re-entrant loop involving TMSs 2 and 3. The APC Superfamily was established to encompass a wider range of homologues.
Members of APC Family
Members of one subfamily within the APC family (SGP; TC# 2.A.3.9) are amino acid receptors rather than transporters and are truncated at their C-termini, relative to the transporters, having 10 TMSs.
The eukaryotic members of another subfamily (CAT; TC# 2.A.3.3) and the members of a prokaryotic subfamily (AGT; TC #2.A.3.11) have 14 TMSs.
The larger eukaryotic and archaeal proteins possess N- and C-terminal hydrophilic extensions. Some animal proteins, for example, those in the LAT subfamily (TC# 2.A.3.8) including ASUR4 (gbY12716) and SPRM1 (gbL25068) associate with a type 1 transmembrane glycoprotein that is essential for insertion or activity of the permease and forms a disulfide bridge with it. These glycoproteins include the CD98 heavy chain protein of Mus musculus (gbU25708) and the orthologous 4F2 cell surface antigen heavy chain of Homo sapiens (spP08195). The latter protein is required for the activity of the cystine/glutamate antiporter (2.A.3.8.5), which maintains cellular redox balance and cysteine/glutathione levels. They are members of the rBAT family of mammalian proteins (TC #8.A.9).
Most S. cerevisiae amino acid permeases are members of the APC family. The majority of these permeases belong to the YAT sub-family (2.A.3.10) and they have a broad range of overlapping specificities. Two additional permeases belong to the LAT sub-family (2.A.3.8.4 and 2.A.3.8.16) and support methionine and cysteine intake. The final one identified is an ACT sub-family (2.A.3.4.3) member, a GABA permease, present in both cell and vacuolar membranes; all others are found only in the cell membrane.
Two APC family members, LAT1 and LAT2 (TC #2.A.3.8.7), transport a neurotoxicant, the methylmercury-L-cysteine complex, by molecular mimicry.
Hip1 of S. cerevisiae (TC #2.A.3.1.5) has been implicated in heavy metal transport.
Subfamilies
Subfamilies of the APC family, and the proteins in these families, can be found in the Transporter Classification Database:
2.A.3.1: The Amino Acid Transporter (AAT) Family
2.A.3.2: The Basic Amino Acid/Polyamine Antiporter (APA) Family
2.A.3.3: The Cationic Amino Acid Transporter (CAT) Family
2.A.3.4: The Amino Acid/Choline Transporter (ACT) Family
2.A.3.5: The Ethanolamine Transporter (EAT) Family
2.A.3.6: The Archaeal/Bacterial Transporter (ABT) Family
2.A.3.7: The Glutamate:GABA Antiporter (GGA) Family
2.A.3.8: The L-type Amino Acid Transporter (LAT) Family (Many LAT family members function as heterooligomers with rBAT and/or 4F2hc (TC #8.A.9))
2.A.3.9: The Spore Germination Protein (SGP) Family
2.A.3.10: The Yeast Amino Acid Transporter (YAT) Family
2.A.3.11: The Aspartate/Glutamate Transporter (AGT) Family
2.A.3.12: The Polyamine:H+ Symporter (PHS) Family
2.A.3.13: The Amino Acid Efflux (AAE) Family
2.A.3.14: The Unknown APC-1 (U-APC1) Family
2.A.3.15: The Unknown APC-2 (U-APC2) Family
Structure and function
Based on 3-D structures of APC superfamily members, Rudnick (2011) has proposed the pathway for transport and suggested a "rocking bundle" mechanism.
Transport reactions
Transport reactions generally catalyzed by APC Superfamily members include:
Solute:proton symport
Solute (out) + nH+ (out) → Solute (in) + nH+ (in).
Solute:solute antiport
Solute-1 (out) + Solute-2 (in) ⇌ Solute-1 (in) + Solute-2 (out).
See also
APC Superfamily
Transporter Classification Database
Membrane transport protein
References
Protein families
Membrane proteins
Transmembrane proteins
Transmembrane transporters
Transport proteins
Integral membrane proteins | APC Family | [
"Biology"
] | 1,285 | [
"Protein families",
"Protein classification",
"Membrane proteins"
] |
71,517,659 | https://en.wikipedia.org/wiki/Time%20in%20Guinea-Bissau | Time in Guinea-Bissau is given by a single time zone, denoted as Greenwich Mean Time (GMT; UTC+00:00). Guinea-Bissau shares this time zone with several other countries, including fourteen in western Africa. Guinea-Bissau does not observe daylight saving time (DST).
IANA time zone database
In the IANA time zone database, Guinea-Bissau is given one zone in the file zone.tab – Africa/Bissau. "GW" refers to the country's ISO 3166-1 alpha-2 country code. Data for Guinea-Bissau directly from zone.tab of the IANA time zone database; columns marked with * are the columns from zone.tab itself:
See also
Time in Africa
List of time zones by country
References
External links
Current time in Guinea-Bissau at Time.is
Time in Guinea-Bissau at TimeAndDate.com
Time by country
Geography of Guinea-Bissau
Time in Africa | Time in Guinea-Bissau | [
"Physics"
] | 201 | [
"Spacetime",
"Physical quantities",
"Time",
"Time by country"
] |
71,519,050 | https://en.wikipedia.org/wiki/Le%20Potier%27s%20vanishing%20theorem | In algebraic geometry, Le Potier's vanishing theorem is an extension of the Kodaira vanishing theorem, on vector bundles. The theorem states the following
In case of r = 1, and let E is an ample (or positive) line bundle on X, this theorem is equivalent to the Nakano vanishing theorem. Also, found another proof.
generalizes Le Potier's vanishing theorem to k-ample and the statement as follows:
gave a counterexample, which is as follows:
See also
vanishing theorem
Barth–Lefschetz theorem
Note
References
Further reading
External links
(OpenContent book)
Theorems in algebraic geometry
Theorems in complex geometry | Le Potier's vanishing theorem | [
"Mathematics"
] | 138 | [
"Theorems in algebraic geometry",
"Theorems in complex geometry",
"Theorems in geometry"
] |
71,519,149 | https://en.wikipedia.org/wiki/Metric%20lattice | In the mathematical study of order, a metric lattice is a lattice that admits a positive valuation: a function satisfying, for any , and
Relation to other notions
A Boolean algebra is a metric lattice; any finitely-additive measure on its Stone dual gives a valuation.
Every metric lattice is a modular lattice, c.f. lower picture. It is also a metric space, with distance function given by With that metric, the join and meet are uniformly continuous contractions, and so extend to the metric completion (metric space). That lattice is usually not the Dedekind-MacNeille completion, but it is conditionally complete.
Applications
In the study of fuzzy logic and interval arithmetic, the space of uniform distributions is a metric lattice. Metric lattices are also key to von Neumann's construction of the continuous projective geometry. A function satisfies the one-dimensional wave equation if and only if it is a valuation for the lattice of spacetime coordinates with the natural partial order. A similar result should apply to any partial differential equation solvable by the method of characteristics, but key features of the theory are lacking.
References
Lattice theory
Metric spaces | Metric lattice | [
"Mathematics"
] | 234 | [
"Mathematical structures",
"Lattice theory",
"Space (mathematics)",
"Metric spaces",
"Fields of abstract algebra",
"Order theory"
] |
71,520,312 | https://en.wikipedia.org/wiki/Lagokarpos | Lagokarpos is an extinct plant genus from the Late Paleocene to early Middle Eocene of North America, Germany and China. Its relationship with modern taxa is unclear.
Etymology
Lago- is from lagós(λαγώς) which means "hare" and karpos is from karpós(καρπός) which means "fruit". The name refers to its rabbit-eared wings.
References
Prehistoric angiosperm genera
Angiosperms
Paleocene plants
Eocene plants | Lagokarpos | [
"Biology"
] | 107 | [
"Plants",
"Angiosperms"
] |
71,520,462 | https://en.wikipedia.org/wiki/NGC%205523 | NGC 5523 is an unbarred spiral galaxy in the constellation of Boötes, registered in New General Catalogue (NGC). The galaxy forms an equilateral triangle with NGC 5641 and NGC 5466 when observed using a telescope from the ground.
Observation history
NGC 5523 was discovered by William Herschel on 19 May 1784 using 18.7-inch f/13 speculum telescope. John Louis Emil Dreyer inside the New General Catalogue, described it as "faint, pretty large, pretty much extended 90°, 10th magnitude star to northwest". It was described in Burnham's Celestial Handbook as "faint, pretty large (5.0'x0.8'), much elongated, nearly edge-on". Steve Coe, an American astronomer, described it as "faint, pretty large, much elongated (3 X 1) in PA 90 and brighter in the middle at 100X."
General
The galaxy was originally thought to be isolated due to its lack of interaction with other galaxies in the past 1 to 3 billion years. However, a 2016 study reported that some irregularities of the contour of the discs and nucleated bulge at the center of the galaxy suggested that the galaxy previously had soft collisions with other galaxies.
Notes
References
Galaxies discovered in 1784
5523
17900519
Unbarred spiral galaxies
NGC 5523
Discoveries by William Herschel | NGC 5523 | [
"Astronomy"
] | 278 | [
"Boötes",
"Constellations"
] |
71,521,240 | https://en.wikipedia.org/wiki/Herbert%20M.%20Sauro | Herbert M. Sauro (born 19 July 1960) is a Welsh biochemist who works in the field of metabolic control analysis and systems biology.
Early and education
Sauro grew up in the village of Llangolman in Pembrokeshire and attended the Welsh comprehensive school Ysgol y Preseli.
After obtaining a B.Sc. in biochemistry with microbiology at the University of Kent Canterbury and an M.Sc. in biological computing at the University of York, Sauro moved to Oxford Brookes University for his Ph.D. (1986) under the direction of David Fell, for a thesis entitled Control analysis and simulation of metabolism, work that led to several publications, including one in which new relationships between elasticities and control coefficients were described. Subsequently he obtained a teaching degree at the University of Aberystwyth.
Research
Sauro carried out post-doctoral research at the University of Edinburgh in association with Henrik Kacser, when he worked on time-dependent systems and enzyme-enzyme interactions.
While a student at Oxford Brookes Sauro wrote a program called SCAMP for modelling metabolic systems, later developed as Jarnac and incorporated in his Systems Biology Workbench.
Together with Hamid Bolouri, Andrew Finney and Michael Hucka he was a member of the development team for the creation of SBML (the Systems Biology Mark-up language),
which has become a major influence on the subject.
In 2018, Sauro's research group published Tellurium, a Python-based modeling environment with applications in system analysis and synthetic biology.
Books
Sauro is the author of books on metabolic control analysis, enzyme kinetics, and Laplace transforms.
Career
After some years, first at Caltech (2000-2005), then at the Keck Graduate Institute in Claremont, California (2004-2007), Sauro moved to the University of Washington as an Associate professor in the department of Bioengineering in 2007. In 2013 he earned the University of Washington College of Engineering, Community of Innovators Awards, Faculty Innovator: Teaching & Learning.
He is currently the director of the NIH Center for Reproducible Biomedical Modeling.
References
Living people
1960 births
Alumni of Aberystwyth University
Alumni of Oxford Brookes University
Alumni of the University of Kent
Alumni of the University of York
People from Pembrokeshire
Systems biologists
Theoretical biologists
Welsh biochemists | Herbert M. Sauro | [
"Biology"
] | 484 | [
"Bioinformatics",
"Theoretical biologists"
] |
71,522,061 | https://en.wikipedia.org/wiki/Meitei%20input%20methods | Meitei input methods are the methods that allow users of computers (desktops, laptops and keyboards) to input texts in the Meitei script (Manipuri script), systematically for Meitei language (officially known as Manipuri language).
Unicode
The Unicode charts of Meetei Mayek script are found in the following PDFs:
https://unicode.org/charts/PDF/UABC0.pdf
https://unicode.org/charts/PDF/UAAE0.pdf
The total number of characters in the Meitei Mayek script are:
56 standard characters
23 extension characters
56 standard characters:
27 mapi characters
8 lonsum characters
8 cheinap characters
3 khudam characters
10 cheising characters (10 digits)
Gboard
The Meitei Mayek Gboard has most of the Unicode characters for the script but it still has some issues. Some characters including (apun), (onap), (eenap/inap) and (lum) are missing. Standard and historical characters are mixed up.
Apple iOS 13
The Apple iOS 13 keyboard system supports the Manipuri language in both Meetei Mayek (Meetei script) as well as Bengali script. Apple users can go to Settings> General>Keyboards>Keyboards> and then tap on Add New Keyboard.
Google Translate
Google Translate supports the phonetic keyboard to type the characters of the Meitei script.
Linux
The Linux software system can render the Meitei Mayek keyboard. To install it, the font file (EPAOMAYEK.ttf) should be copied to fonts:/// in the File Manager of the user.
Macintosh operating systems
Mac OS can render the Meitei Mayek keyboard, in various forms.
It can be installed under Mac OS X as follows : font file (EPAOMAYEK.ttf) >> /Library/Fonts (for all users),
or >> /Users/Your_username/Library/Fonts (for your personal use only).
If the Font Book is present in the user's OS, then: double-click on a font file >> a preview pops with an "Install font" button.
It can also be installed under Mac OS 9 or less as follows: the fonts suitcases should be dragged into the System folder and should be added to the Fonts folder
Microsoft SwiftKey keyboard
In the year 2015, the Microsoft SwiftKey keyboard supported Meitei (Manipuri), during its addition of 9 new Indian languages to the software system.
Windows
The Manipuri Keyboard or Meitei Mayek Keyboard on the Windows was developed by Nongthonbam Tonthoi. Its version is 1.6.0. It can be installed on the Windows by using Android App Players like BlueStacks, Nox, KOPlayer, etc.
It can be installed under the Windows Vista as follows :
Select the font file (EPAOMAYEK.ttf) >> Right-click >> Install.
It can also be installed under any version of Windows as follows :
Place the font file (EPAOMAYEK.ttf) into the Fonts folder, usually C:\Windows\Fonts or C:\WINNT\Fonts
(or by the Start Menu >> Control Panel >> Appearance and Themes >> Fonts).
See also
Meetei Mayek (Unicode block)
Meetei Mayek Extensions (Unicode block)
Wikipedia:Meitei script display help
List of Meitei-language newspapers
Meitei inscriptions
References
External links
Meitei language
Meitei script
Keyboard layouts
Input methods
Indic computing | Meitei input methods | [
"Technology"
] | 749 | [
"Input methods",
"Natural language and computing"
] |
71,522,116 | https://en.wikipedia.org/wiki/Lutetium%20vanadate | Lutetium vanadate is inorganic compound with ferromagnetic and semiconducting properties, with the chemical formula of Lu2V2O7 with the same structure as pyrochlore.
Preparation
Lutetium vanadate can be obtained by the reaction between lutetium oxide, vanadium trioxide and vanadium pentoxide at a high temperature (1400 °C) in an argon atmosphere with oxygen pressure of 2.0×10−5 bar.
2 Lu2O3 + V2O3 + V2O5 → 2 Lu2V2O7
See also
Ytterbium-doped lutetium orthovanadate
References
Lutetium compounds
Vanadates
Vanadium(IV) compounds | Lutetium vanadate | [
"Chemistry"
] | 157 | [
"Inorganic compounds",
"Inorganic compound stubs"
] |
71,522,734 | https://en.wikipedia.org/wiki/Fluorohydride%20salt | Fluorohydride salts are ionic compounds containing a mixture of fluoride and hydride anions, generally with strongly electropositive metal cations. Unlike other types of mixed hydrides such as oxyhydrides, fluorohydride salts are typically solid solutions because of the similar sizes and identical charges of fluoride and hydride ions.
Examples
Fluorohydride salts typically contain one or more alkali or alkaline earth metals whose parent fluorides and hydrides are predominantly ionic. Examples with a single metal counterion include Li(H,F), Na(H,F), Mg(H,F)2, and Ca(H,F)2. More complex fluorohydride salts include the perovskite-structured NaMg(H,F)3 and MCa(H,F)3 (M = Rb or Cs), and the high-pressure pyrochlore compound NaCaMg2(H,F)7.
Applications
Fluorohydride salts have drawn interest as thermoelectric storage materials because their continuous solid-solution range enables balancing of hydrogen-storage capacity with thermal stability. Replacing hydride with fluoride ions in solid solution reduces the hydrogen-storage capacity of the compound but also reduces the hydrogen-dissociation pressure, enabling higher-temperature operation. With sodium fluorohydride, the maximum rate of hydrogen release (and thus pressure buildup) is found to be 443 °C for the solid solution with 1:1 H:F ratio, versus 408 °C for the pure sodium hydride. A cost comparison reveals that a hydrofluoride salt with the composition NaMgH2F can be operated at lower cost than the parent hydride NaMgH3 and other magnesium-hydride based materials, despite its lower hydrogen-storage capacity, because of the improved stability of the fluorohydride salt at high temperature.
References
Fluorides
Mixed anion compounds
Hydrides | Fluorohydride salt | [
"Physics",
"Chemistry"
] | 422 | [
"Matter",
"Mixed anion compounds",
"Salts",
"Fluorides",
"Ions"
] |
71,523,018 | https://en.wikipedia.org/wiki/BG%20Canis%20Minoris | BG Canis Minoris is a binary star system in the equatorial constellation of Canis Minor, abbreviated BG CMi. With an apparent visual magnitude that fluctuates around 14.5, it is much too faint to be visible to the naked eye. Parallax measurements provide a distance estimate of approximately 2,910 light years from the Sun.
In 1981, I. M. McHardy and associates included the X-ray source '3A 0729+103' in their Ariel 5 satellite 3A catalogue. The team used a localized search of those coordinates with the Einstein Observatory to isolate an X-ray source that matched the location of a blue-hued star with a visual magnitude of 14.5. The light curve for this star proved quite similar to other intermediate polars that had been identified as X-ray sources. The overall brightness variation of 3A 0729+103 matched a binary system with an orbital period of 194.1 minutes. It displays a more rapid variation with a period of 913 seconds, which was interpreted as related to a spin period.
The standard model for this category of variable star consists of a magnetized white dwarf in a close orbit with a cool main sequence secondary star. The Roche lobe of the secondary is overflowing, and this stream of matter is falling onto an accretion disk in orbit around the primary. X-ray observations with the EXOSAT observatory in 1984–1985 demonstrated there are two regions of emission. One of these is believed to be at the magnetic poles of the white dwarf component, while the second is located where the accretion stream is striking the white dwarf's magnetosphere. The emission at the pole is partially eclipsed by the rotation of the white dwarf.
In 1987, cyclotron radiation was discovered based on the circular polarization of its near infrared output, the first conclusive identification of this behavior for an intermediate polar. This emission confirmed the model of a magnetic white dwarf that is accreting mass. Measurements suggested a magnetic field strength of . Changes in the rotation period over time indicate that the white dwarf is slowly being spun up due to torque from accreted matter. It has an estimated 78% of the mass of the Sun, while the donor companion has about 38%.
References
Further reading
White dwarfs
Red dwarfs
Intermediate polars
Astronomical X-ray sources
Canis Minor
Canis Minoris, BG | BG Canis Minoris | [
"Astronomy"
] | 488 | [
"Astronomical X-ray sources",
"Canis Minor",
"Astronomical objects",
"Constellations"
] |
71,527,146 | https://en.wikipedia.org/wiki/Soda%20oppositifolia | Soda oppositifolia is a species of halophyte shrub native to the Mediterranean Basin.
Description
This annual, woody plant can grow into shrubs up to 2 m tall. It has cylindrical-linear and opposed leaves. The flowers, which bloom from May to October, are hermphrodyte and have a size of 1 cm.
Taxonomy
Salsola oppositifolia was first described by René Louiche Desfontaines and published in Flora Atlantica 1: 219. 1798.
Uses
This plant has been historically used, along with other Soda species, as a source of soda ash, in the manufacture of lye and soaps.
References
External links
Amaranthaceae
Halophytes
Industrial history
Plants described in 1798
Barilla plants
Flora of Algeria
Flora of Spain
Flora of Tunisia | Soda oppositifolia | [
"Chemistry"
] | 160 | [
"Halophytes",
"Salts"
] |
71,527,412 | https://en.wikipedia.org/wiki/Hepatokine | Hepatokines (Greek heapto-, liver; and -kinos, movement) are proteins produced by liver cells (hepatocytes) that are secreted into the circulation and function as hormones across the organism. Research is mostly focused on hepatokines that play a role in the regulation of metabolic diseases such as diabetes and fatty liver and include: Adropin, ANGPTL4, Fetuin-A, Fetuin-B, FGF-21, Hepassocin, LECT2, RBP4,Selenoprotein P, Sex hormone-binding globulin.
Function
Hepatokines are hormone-like proteins secreted by hepatocytes, and many have been associated with extra-hepatic metabolic regulation. Through processes like autocrinem, paracrinem, and endocrine signaling, hepatokines can influence metabolic processes. It has been stated that, "hepatocytes secrete more than 560 types of hepatokines, many of which regulate metabolic and inflammatory diseases in the liver or at distant organs through circulation delivery." Hepatocytes can secrete multiple hepatokines into the blood. In particular, these hepatokines, similar to hypothalamic hormones and insulin, are structurally polypeptides, and proteins and are transcribed and expressed by specific genes.
The liver may emit hepatokines to influence energy homeostasis and inflammation under pressure on the metabolism like long-term starvation or over-nutrition. If the liver is unable to fulfill this process, the corresponding disease develops like fatty liver disease from, "impaired hepatic insulin-sensitizing substance production." Hepatokines signal energy status and help regulate nutrient availability to multiple peripheral tissues and the central nervous system (CNS). Hepatokines have been described to be involved in the regulation of energy and nutrient metabolism by acting directly on the liver or on distal target tissues. These proteins regulate glucose and lipid metabolism in the liver but also in the skeletal muscle or the adipose tissue. It is now clear that a single session of exercise is accompanied by the production of liver-secreted proteins. Hepatokines can also mediate the beneficial effects of chronic exercise or, at least, represent biomarkers of training-induced metabolic improvements. Hepatokines directly affect the progression of atherosclerosis by modulating endothelial dysfunction and infiltration of inflammatory cells into vessel walls.
Types
Fetuin-A was the first hepatokine to be described and correlated with increased inflammation and insulin resistance.
Fetuin-B significantly increases hepatic steatosis and mediates impaired insulin action and glucose intolerance.
ANGPTL8/betatrophin, initially proposed for its action on beta cell proliferation, although this effect has recently been brought into question.
FGF-21 an insulin-sensitising hormone that is an appealing drug target because of its beneficial metabolic actions.
Adropin is linked to macronutrient intake and estrogen.
ANGPTL4 can inhibit lipoprotein lipase and activate cAMP-stimulated lipolysis in adipocytes.
Clinical significance
Hepatokines can serve as biomarkers and are potential therapeutic targets for metabolic diseases. The liver through execretion of hepatokines regulates the whole bodies metabolism in response to stress signals.
Secreted hepatokines in response to exercise induce favorable metabolic changes in fat, blood vessles, and skeletal muscle that can reduce metabolic diseases.
Although substantial progress has been made in understanding disease-controlled production of hepatokines, there is still so much to discover. There is so much room for discovery. For example, "little is known about the inductive mechanism of transcriptional reprogramming, protein translation, modification, and secretion of hepatokines, particularly through the ER and Golgi, and more. The identification and functional characterization of hepatokines may provide significant insights that could help in better understanding of MetS pathogenesis.
Non-alcoholic fatty liver disease
Hepatokines, sometimes referred to as hepatocytes-derived cytokines have been shown to relate to non-alcoholic fatty liver disease. "Mounting evidence has revealed that the secretory profiles of hepatokines are significantly altered in non-alcoholic fatty liver disease (NAFLD), the most common hepatic manifestation, which frequently precedes other metabolic disorders, including insulin resistance and type 2 diabetes. Therefore, deciphering the mechanism of hepatokine-mediated inter-organ communication is essential for understanding the complex metabolic network between tissues, as well as for the identification of novel diagnostic and/or therapeutic targets in metabolic disease. Not only are they involved with metabolic diseseases but they are also linked to diseases of other organs, such as the heart, muscle, bone, and eyes. Recently, it was reported that hepatokine, a secretory protein released from the liver, could affect muscle and fat metabolic phenotypes in an endocrine-dependent manner.
Metabolic diseases
Early studies in the area reported that a liver-derived protein, alpha2-HS Glycoprotein, also known as Fetuin-A, can inhibit insulin tyrosine kinase activation and might play a role in the pathogenesis of metabolic disorders. Results suggest that hepatokine production could remodel metabolic homeostasis. This is exemplified by a number of studies revealing that hepatokines play a pivotal role in metabolism and contribute to the development of obesity, insulin resistance, T2D, NAFL, and NASH (109, 149). So far, ~20 hepatokines have been described to be involved in the regulation of energy and nutrient metabolism by acting directly on the liver or on distal target tissues. Hepatokines are now considered potential targets for the treatment of cardiometabolic disorders.
See also
Adipokines
Myokines
References
Endocrinology
Liver
Peptide hormones | Hepatokine | [
"Chemistry"
] | 1,243 | [
"Biochemistry stubs",
"Protein stubs"
] |
71,527,563 | https://en.wikipedia.org/wiki/Gadolinium%20diiodide | Gadolinium diiodide is an inorganic compound, with the chemical formula of GdI2. It is an electride, with the ionic formula of Gd3+(I−)2e−, and therefore not a true gadolinium(II) compound. It is ferromagnetic at 276 K with a saturation magnetization of 7.3 B; it exhibits a large negative magnetoresistance (~70%) at 7 T near room temperature. It can be obtained by reacting gadolinium and gadolinium(III) iodide at a high temperature:
Gd + 2 GdI3 → 3 GdI2
It can react with hydrogen at high temperature (800 °C) to obtain gadolinium hydrogen iodide (GdI2H0.97).
References
Gadolinium compounds
Iodides
Electrides
Ferromagnetic materials
Lanthanide halides | Gadolinium diiodide | [
"Physics",
"Chemistry"
] | 197 | [
"Electron",
"Inorganic compounds",
"Electrides",
"Ferromagnetic materials",
"Inorganic compound stubs",
"Salts",
"Materials",
"Matter"
] |
71,528,348 | https://en.wikipedia.org/wiki/ISO%2025119 | ISO 25119, titled "Tractors and machinery for agriculture and forestry – Safety-related parts of control systems", is an international standard for functional safety of electrical and/or electronic systems that are installed in tractors and machines used in agriculture and forestry, defined by the International Organization for Standardization (ISO).
Parts of ISO 25119
ISO 25119 consists of following parts:
General principles for design and development
Concept phase
Series development, hardware and software
Production, operation, modification and supporting processes
See also
IEC 61508
References
25119
Safety engineering | ISO 25119 | [
"Engineering"
] | 109 | [
"Safety engineering",
"Systems engineering"
] |
71,529,348 | https://en.wikipedia.org/wiki/Gaia%20catalogues | The Gaia catalogues are star catalogues created using the results obtained by Gaia space telescope.
The catalogues are released in stages that will contain increasing amounts of information; the early releases also miss some stars, especially fainter stars located in dense star fields. Data from every data release can be accessed at the Gaia archive.
Initial Gaia Source List
The Initial Gaia Source List (IGSL) is a star catalogue of 1.2 billion objects created in support of the Gaia mission. The mission should have delivered a catalogue based entirely on its own data. For the first catalogue, Gaia DR1, a way was needed to be able to assign the observations to an object and to compare them with the objects from other star catalogues. For this purpose, a separate catalog of objects from several other catalogues was compiled, which roughly represents the state of knowledge of astronomy at the beginning of the Gaia mission.
Attitude Star Catalog
The Attitude Star Catalog is a subset of the IGSL, required for the first approximation in the iterative evaluation of the Gaia data. A first version was created in 2013, a more refined version in April 2014. In total, the Attitude Star Catalog contains 8,173,331 entries with information on position, proper motion and magnitude. Starting with Gaia DR2, the Attitude Star Catalog was replaced with a new list generated from the Gaia Main Data Base (MDB), using the same criteria.
Gaia Spectrophotometric Standard Star Catalogue
IGSL contains a list of about 200 stars of different spectral classes and magnitudes needed for calibration of the photometric measurements. It is the result of the Gaia Spectrophotometric Standard Stars Survey (SPSS), a selection of stars using Earth-based data in advance of the Gaia mission. Previous catalogues for calibrating magnitudes could not be used for the mission because many of these objects are too bright for Gaia to detect. It was anticipated that some of the stars selected may be previously unrecognized doubles or variable stars that would need to be deleted from the catalogue; for this reason the list contains more stars than necessary. For Gaia EDR3 (Early Data Release 3), a selection was made from more than 100,000 objects that were used for the calibration. These are well-observed objects selected according to Stetson Secondary Standards, but only Gaia data were used.
Gaia Initial Quasar Catalog
A list of quasars based on the Large Quasar Astrometric Catalog was prepared for IGSL. This in turn goes back to the Sloan Digital Sky Survey. From the more than one million objects, a selection of 150,000 quasars was made, which are in the region of Gaia's magnitude limit. The selected objects are already well observed and documented. In most cases, quasars are very far away, so that their proper motions and parallaxes are negligibly small.
Gaia Ecliptic Pole Catalogue
Gaia Ecliptic Pole Catalogue (GEPC) was created for measuring the poles. The southern part of the catalogue was compiled from observations made with the MPG/ESO telescope at the Max Planck Institute for Astronomy in La Silla, Chile. It contains precise positions, UBV I photometry for the southern field and the corresponding magnitudes. The northern part was created with the Canada–France–Hawaii Telescope on Mauna Kea, Hawaii.
The GEPC v3.0 catalogue contains 612,946 objects from a field of one square degree each at the north and south poles. The north pole is relatively sparse and contains 164,468 objects, while the south pole is still in the region of the Large Magellanic Cloud and contains 448,478 objects. The GEPC data was needed right at the beginning of the mission for the initial calibration. The commissioning phase of the Gaia space probe ended on July 18, 2014. This was followed by a calibration phase of 28 days, during which the ecliptic poles were measured intensively. During this time, Gaia was operated in Ecliptic Poles Scan Law mode (EPSL), in which the two poles were measured twice during each revolution. The initial catalogue was used for Gaia DR1 to match Gaia-found objects to previous star catalogues.
Gaia DR1
Gaia DR1, the first data release based on 14 months of observations made through September 2015, took place on 13 September 2016. It includes "positions and magnitudes in a single photometric band for 1.1 billion stars using only Gaia data, positions, parallaxes and proper motions for more than 2 million stars" based on a combination of Gaia and Tycho-2 data for those objects in both catalogues, "light curves and characteristics for about 3000 variable stars, and positions and magnitudes for more than 2000 extragalactic sources used to define the celestial reference frame".
Gaia DR2
The second data release (DR2), which occurred on 25 April 2018, is based on 22 months of observations made between 25 July 2014 and 23 May 2016. It includes positions, parallaxes and proper motions for about 1.3 billion stars and positions of an additional 300 million stars in the magnitude range g = 3–20, red and blue photometric data for about 1.1 billion stars and single colour photometry for an additional 400 million stars, and median radial velocities for about 7 million stars between magnitude 4 and 13. It also contains data for over 14,000 selected Solar System objects.
The coordinates in DR2 use the second Gaia celestial reference frame (Gaia–CRF2), which is based on observations of 492,006 sources believed to be quasars and has been described as "the first full-fledged optical realisation of the ICRS ... built only on extragalactic sources." Comparison of the positions of 2,843 sources common to Gaia–CRF2 and a preliminary version of the ICRF3 shows a global agreement of 20 to 30 μas, although individual sources may differ by several mas. Since the data processing procedure links individual Gaia observations with particular sources on the sky, in some cases the association of observations with sources will be different in the second data release. Consequently, DR2 uses different source identification numbers than DR1. A number of issues have been identified with the DR2 data, including small systematic errors in astrometry and significant contamination of radial velocity values in crowded star fields, which may affect some one percent of the radial velocity values. Ongoing work should resolve these issues in future releases. A guide for researchers using Gaia DR2, which collected "all information, tips and tricks, pitfalls, caveats and recommendations relevant to" DR2, was prepared by the Gaia Helpdesk in December 2019.
Gaia DR3
Due to uncertainties in the data pipeline, the third data release, based on 34 months of observations, has been split into two parts so that data that was ready first, was released first. The first part, EDR3 (Early Data Release 3), consisting of improved positions, parallaxes and proper motions, was released on 3 December 2020. The coordinates in EDR3 use a new version of the Gaia celestial reference frame (Gaia–CRF3), based on observations of 1,614,173 extragalactic sources, 2,269 of which were common to radio sources in the third revision of the International Celestial Reference Frame (ICRF3). Included is the Gaia Catalogue of Nearby Stars (GCNS), containing 331,312 stars within (nominally) .
The full DR3, published on 13 June 2022, includes the EDR3 data plus Solar System data; variability information; results for non-single stars, for quasars, and for extended objects; astrophysical parameters; and a special data set, the Gaia Andromeda Photometric Survey (GAPS), providing a photometric time series for about 1 million sources located in a 5.5-degree radius field centered on the Andromeda galaxy. The release dates of EDR3 and DR3 were delayed by the effects of the COVID-19 pandemic on the Gaia Data Processing and Analysis Consortium.
Gaia Focused Product Release
Gaia Focused Product Release from October 2023 focused on Omega Centauri and contained more that half a million stars from that region.
Gaia DR4 and DR5
The full data release for the five-year nominal mission, DR4, will include full astrometric, photometric and radial-velocity catalogues, variable-star and non-single-star solutions, source classifications plus multiple astrophysical parameters for stars, unresolved binaries, galaxies and quasars, an exo-planet list and epoch and transit data for all sources. Most measurements in DR4 are expected to be 1.7 times more precise than DR2; proper motions will be 4.5 times more precise. DR4 is expected to be released no earlier than mid-2026.
The last catalogue, DR5, will consist of all data collected during the lifespan of the mission. It will be 1.4 times more precise than DR4, while proper motions will be 2.8 times more precise than DR4. It will be published no earlier than the end of 2030.
Gaia Archive
The Gaia Archive is a catalogue that contains positions and brightnesses for 1.7 billion stars, including distances and proper motions for more than 1.3 billion stars.
An outreach application, Gaia Sky, has been developed to explore the galaxy in three dimensions using Gaia data.
See also
Data Processing and Analysis Consortium
List of astronomical catalogues
References
External links
Gaia DR3 Documentation
Gaia EDR3 Documentation
Gaia DR2 Documentation
Gaia DR1 Documentation
ESA Gaia page
Gaia Archive
Astrometry
Catalogue | Gaia catalogues | [
"Astronomy"
] | 2,044 | [
"Works about astronomy",
"Astrometry",
"Astronomical catalogues",
"Astronomical objects",
"Astronomical sub-disciplines",
"Stellar astronomy"
] |
71,530,439 | https://en.wikipedia.org/wiki/List%20of%20countries%20by%20number%20of%20deaths | The following list sorts sovereign states and dependent territories and by the total number of deaths. Figures are from the 2024 revision of the United Nations World Population Prospects report, for the calendar year 2023.
List of countries by number of deaths
Countries and dependent territories by the number of deaths in 2023 according to the World Population Prospects 2024 of the United Nations Department of Economic and Social Affairs.
See also
List of countries by mortality rate
List of countries by life expectancy
List of countries by number of births
References
External links
United Nations, Department of Economic and Social Affairs – Population Division – World Population Prospects, the 2022 Revision
Deaths
Deaths
Demographic economics
Human geography
Death-related lists | List of countries by number of deaths | [
"Environmental_science"
] | 136 | [
"Environmental social science",
"Human geography"
] |
71,530,764 | https://en.wikipedia.org/wiki/Blackwell%27s%20contraction%20mapping%20theorem | In mathematics, Blackwell's contraction mapping theorem provides a set of sufficient conditions for an operator to be a contraction mapping. It is widely used in areas that rely on dynamic programming as it facilitates the proof of existence of fixed points. The result is due to David Blackwell who published it in 1965 in the Annals of Mathematical Statistics.
Statement of the Theorem
Let be an operator defined over an ordered normed vector space . is a contraction mapping with modulus if it satisfies
Proof of the Theorem
For all and , . Properties 1. and 2. imply that , hence, .
The symmetric follows from a similar argument and we prove that is a contraction mapping.
Applications
The cake eating problem
An agent has access to only one cake for its entire, infinite, life. It has to decide the optimal way to consume it. It evaluates a consumption plan, , by using a separable utility function, , with discounting factor . Its problem can be summarized as
. ()
Applying Bellman's principle of optimality we find ()'s corresponding Bellman equation
. ()
It can be proven that the solution to this functional equation, if it exists, is equivalent to the solution of (). To prove its existence we can resort to Blackwell's sufficient conditions.
Define the operator . A solution to () is equivalent to finding a fixed-point for our operator. If we prove that this operator is a contraction mapping then we can use Banach's fixed-point theorem, and conclude that there is indeed a solution to ().
First note that is defined over the space of bounded functions since for all feasible consumption plans, . Endowing it with the sup-norm we conclude that the domain and co-domain are ordered normed vector spaces. We are just left with verifying that the conditions for Blackwell's theorem are respected:
(monotonicity) then
(discounting) where is a constant function.
References
Fixed-point theorems
Metric geometry
Linear operators | Blackwell's contraction mapping theorem | [
"Mathematics"
] | 401 | [
"Theorems in mathematical analysis",
"Functions and mappings",
"Mathematical objects",
"Fixed-point theorems",
"Linear operators",
"Theorems in topology",
"Mathematical relations"
] |
71,531,231 | https://en.wikipedia.org/wiki/ZOBODAT | ZOBODAT is an online catalogue of taxonomic, bibliographic, author and specimen data, from mainly German language sources. The database is published by and was founded in 1972 by . At August 16, 2022, it contained 3,476,485 occurrence records, 1,089 journal records (together with their contents), 25,379 authors (including their publications, and specimens collected and determined), and information on 62,977 species.
The reader may access the information in German, French, English, Spanish, Portuguese or Hungarian.
References
External links
Biological databases
Taxonomy (biology) | ZOBODAT | [
"Biology"
] | 127 | [
"Bioinformatics",
"Biological databases",
"Taxonomy (biology)"
] |
57,652,073 | https://en.wikipedia.org/wiki/Sensorimotor%20network | The sensorimotor network (SMN), also known as somatomotor network, is a large-scale brain network that primarily includes somatosensory (postcentral gyrus) and motor (precentral gyrus) regions and extends to the supplementary motor areas (SMA). The auditory cortex may also be included, as well as the visual cortex. The SMN is activated during motor tasks, such as finger tapping, indicating that the network readies the brain when performing and coordinating motor tasks.
Clinical significance
Dysfunction in the SMN has been implicated in various neuropsychiatric disorders.
Bipolar Disorder: The psychomotor disturbances that characterize the depressive and manic phases of bipolar disorder may be related to dysfunction in the sensorimotor network (SMN) and its balance with other large-scale networks such as the default mode network.
Amyotrophic Lateral Sclerosis: Altered functional connectivity patterns in the SMN may contribute to various symptoms in the neurodegenerative disease .
Nomenclature
In 2019, Uddin et al. proposed that pericentral network (PN) be used as a standard anatomical name for the network.
References
Neuroscience
Brain | Sensorimotor network | [
"Biology"
] | 247 | [
"Neuroscience"
] |
57,653,635 | https://en.wikipedia.org/wiki/Sterculic%20acid | Sterculic acid is a cyclopropene fatty acid. It is found in various plants of the genus Sterculia, including being the main component of Sterculia foetida seed oil.
Biosynthesis
The biosynthesis of sterculic acid begins with the cyclopropanation of the alkene of phospholipid-bound oleic acid, an 18-carbon cis-monounsaturated fatty acid. This transformation involves two mechanistic steps: electrophilic methylation with S-adenosyl methionine to give a carbocationic reactive intermediate, followed by cyclization via loss of H+ mediated by a cyclopropane-fatty-acyl-phospholipid synthase enzyme. The product, dihydrosterculic acid, is converted to sterculic acid by dehydrogenation of the cis-disubstituted cyclopropane to cyclopropene. An additional step of α oxidation removes one carbon from the carboxy chain to form the 17-carbon-chain structure of malvalic acid.
References
Fatty acids
Cyclopropenes | Sterculic acid | [
"Chemistry"
] | 250 | [
"Organic compounds",
"Organic compound stubs",
"Organic chemistry stubs"
] |
57,653,651 | https://en.wikipedia.org/wiki/Flumezapine | Flumezapine is an abandoned, investigational antipsychotic drug that was studied for the treatment of schizophrenia. Flumezapine failed clinical trials due to concern for liver and muscle toxicity. Flumezapine is structurally related to the common antipsychotic olanzapine—a point that was used against its manufacturer, Eli Lilly and Company, in a lawsuit in which generic manufacturers sought to void the patent on brand name olanzapine (Zyprexa). Although flumezapine does not differ greatly from olanzapine in terms of its structure, the difference was considered to be non-obvious, and Eli Lilly's patent rights on Zyprexa were upheld.
Medical uses
Flumezapine was studied for the treatment of schizophrenia.
Adverse effects
In the clinical trial that lead to the cessation of its development as a drug, flumezapine was noted to be toxic. The administration of flumezapine led to the adverse effects of elevating the plasma concentration of creatine phosphokinase (CPK) and the liver enzymes aspartate transaminase (AST) and alanine transaminase (ALT). These liver enzyme elevation risks are similar to that of the neuroleptic drug chlorpromazine. Flumezapine also induced extrapyramidal symptoms (EPS) in patients during early clinical trials.
Pharmacology
Flumezapine is classified as a second-generation antipsychotic, which includes other drugs such as clozapine.
Mechanism of action
Flumezapine is an antipsychotic, due to its antagonism of dopamine receptors in the brain. However, like other antipsychotics, it also antagonizes other receptors in the brain, such as the muscarinic receptors. In comparison to clozapine, another antipsychotic, flumezapine's antidopaminergic to anticholinergic ratio is 5 times higher, indicating higher dopamine receptor blockade with less anticholingergic properties.
Chemistry
Flumezapine is a thioeno[2,3-b][1,5]benzodiazepine akin to olanzapine, differing only by the substitution of a fluorine atom (F) for a hydrogen atom (H) on the phenyl ring. The fluorine atom acts as an electron-withdrawing substituent; this was the same rationale given in the patent information for the electron-withdrawing chlorine atom on the antipsychotic clozapine.
History
Developed alongside olanzapine by Eli Lilly and Company, the clinical development of flumezapine was halted due to toxicology concerns. Its research designation was LY-120363. The other analogues studied, (1) substituting flumezapine's methyl group for an ethyl group (ethyl flumezapine) and (2) substituting flumezapine's methyl group for an ethyl group and its fluorine atom for a hydrogen atom, also failed due to concerns of granulocyte suppression and elevated cholesterol during in vivo studies on dogs, respectively.
Society and culture
Controversies
In 2005, flumezapine was at the heart of a lawsuit filed by drug manufacturer Eli Lilly against three generic drug manufacturers (Zenith Goldline Pharmaceuticals, Dr. Reddy's Laboratories, and Teva Pharmaceuticals) that sought to develop generic versions of Zyprexa (olanzapine). The generic companies claimed the Eli Lilly's patent on olanzapine was null and void due to the expiration of the similar compound, flumezapine, from which the discovery of olanzapine would be inevitable. In the judge's ruling, the U.S. District Court for the Southern District of Indiana sided with Eli Lilly by upholding Eli Lilly's patent (Patent No. 5,229,382), finding that the substitution of a fluorine atom for a hydrogen atom in olanzapine was a non-obvious difference between the two compounds, which deserved continued patent protection. As Nicole L. M. Valtz writes in her commentary on the case,
The selection patent was also upheld in Canada.
The patent for Zyprexa expired in 2011.
References
External links
Eli Lilly v. Zenith Goldline, 471 F.3d 1369 (Fed. Cir. 2006)
Abandoned drugs
Thienobenzodiazepines | Flumezapine | [
"Chemistry"
] | 920 | [
"Drug safety",
"Abandoned drugs"
] |
57,654,263 | https://en.wikipedia.org/wiki/Museum%20of%20Concrete | The Museum of Concrete is the first museum in Ukraine dedicated to concrete. The museum is in Odesa on the site of an enterprise that produces building materials. The opening of the museum was held on December 5, 2017. At the time of the opening, two thematic halls were organized. Since January 2018, two rooms have been added. As of May 2018, the museum collection numbered about 2500 exhibits, which are associated with concrete and the technology of its production.
Decor
The first place is occupied by an exposition about the history of the appearance of concrete and its development as a building material from Ancient Rome to fiberglass. Separately presented area a wide range of reagents used in the modern production of concrete products, such as hydrophobicity additives, and plasticizers.
The second hall recreates the atmosphere of the Soviet era and demonstrates the working conditions of the engineer of an industrial enterprise for the production of reinforced concrete. In the hall there is also a technical library on construction topics and reinforced concrete products.
Interactive hall
The hall contains interactive stands connected, for example, with the production and storage of reinforced concrete panels, which were used in the construction of houses of Khrushchev's building. Separate exposition: laboratory measuring equipment for metal and metal forms. The exposition demonstrates direct participation in the materials of concrete products and concrete products.
Notes
External links
Museums in Odesa
Concrete | Museum of Concrete | [
"Engineering"
] | 279 | [
"Structural engineering",
"Concrete"
] |
57,654,403 | https://en.wikipedia.org/wiki/Cyanobacterin | Cyanobacterin is a chemical compound produced by the cyanobacteria Scytonema hofmanni. It is a photosynthesis inhibitor with algaecidal and herbicidal effects.
References
Cyanotoxins
Algaecides
Herbicides
Tertiary alcohols
Benzodioxoles
Chloroarenes
Halogen-containing natural products
Isopropyl compounds
Lactones
Haloalkenes | Cyanobacterin | [
"Chemistry",
"Biology"
] | 86 | [
"Herbicides",
"Biocides",
"Algae",
"Algaecides"
] |
57,654,433 | https://en.wikipedia.org/wiki/OpenALPR | OpenALPR is an automatic number-plate recognition library written in C++. The software is distributed in both a commercial and open source version.
History
OpenALPR was originally developed by a two-man team led by Matt Hill. The open source software became available as a free download at the end of 2015. In March 2016, OpenALPR launched paid Cloud API service and in February 2017 introduced the OpenALPR agent for Axis Communications cameras.
In August 2017 an Australian web developer Tait Brown became known by creating an alternative to an 86 million AUD project of Victoria Police by using OpenALPR.
In March 2018 ProgrammableWeb added OpenALPR to its list of Recognition APIs.
Software
OpenALPR is an automatic number-plate recognition library written in C++. The software is distributed in both a commercial cloud based version and open source version. OpenALPR makes use of OpenCV and Tesseract OCR libraries. It could be run as a command-line utility, standalone library, or background process. The software also integrates with video management systems (VMS) such as Milestone XProtect.
References
External links
OpenALPR at GitHub
Automatic number plate recognition
Automatic identification and data capture
2014 software | OpenALPR | [
"Technology"
] | 254 | [
"Data",
"Automatic identification and data capture"
] |
57,654,857 | https://en.wikipedia.org/wiki/Chloroeremomycin | Chloroeremomycin is a member of the glycopeptide family of antibiotics, such as vancomycin. The molecule is a non-ribosomal polypeptide that has been glycosylated. It is composed of seven amino acids and three saccharide units. Although chloroeremomycin has never been used in human medicine, oritavancin, a semi-synthetic derivative of chloroeremomycin, has full FDA approval.
Chloroeremomycin is a type of glycopeptide antibiotic and works by blocking the construction of a cell wall. Chloroeremomycin is naturally produced by Amycolatopsis orientalis.
History
Chloroeremomycin was discovered by Eli Lilly in the 1980s. In the 1990s, researchers at Eli Lilly developed biphenyl-chloroeremomycin, now known as oritavancin, as a functionalized derivative of chloroeremomycin to combat rising antibacterial resistance to vancomycin. The chloroeremomycin gene cluster was sequenced by van Wageningen et al in 1998. After the publication, many groups expressed the genes and conducted experiments to understand how chloroeremomycin and, by extension, vancomycin are biosynthesized.
Structure
Chloroeremomycin is composed of seven amino acids (three non-proteinogenic, and four proteinogenic) and three saccharide units. From N-terminus to C-terminus, the order is: Me-L-Leu, L-Tyr, D-Asn, D-4-hydroxyphenylglycine (HPG), L-HPG, D-Tyr, and D-3,5-dihydroxyphenylglycine (DHPG). When referring to specific amino acids, this article will reference the amino acid in the order it appears within the heptapeptide. Chloroeremomycin is glycosylated at aa4 with a Glc-(2→α1)-epivancosamine disaccharide and at aa6 with a D-BHT-(→α1)-epivancosamine saccharide.
Some amino acids are modified prior to the completion of the heptapeptide (in cis) and some are modified after the heptapeptide is formed (in trans). During the synthesis of the heptapeptide, the stereocenters of aa3, aa4, aa6, and aa7 are changed from L to D. Both Tyr residues are hydroxylated and chlorinated after the amino acids have been incorporated to the growing polypeptide to form 4-chloro-β-hydroxytyrosine (BHT). The now-BHT residues are then crosslinked to the aa4 HPG through aryl-ether linkages. An aryl-aryl bond is formed between aa5 and aa7 at the aa5-C3 and aa7-C2 positions on the aromatic rings. Finally, the N-terminus Leu is methylated.
In addition to the presence of D-amino acids, the molecule has atropisomer chemistry. The orientations of the chloro-substituted phenyl rings add another aspect of stereochemistry to the molecule.
Biosynthesis
Chloroeremomycin was found to be synthesized by Amycolatopsis orientalis.
Non-ribosomal peptide synthase
The non-ribosomal peptide synthase (NRPS) is encoded by three genes: CepA, CepB, and CepC. CepA links the first three amino acids; CepB adds the fourth to sixth amino acids; CepC adds the last amino acid and includes a thioesterase domain to release the heptapeptide from the NRPS complex. The growing peptide chain is passed through modules for each amino acid. The basic organization of each module is A-PCP-C. The A, or adenylation, region activates the domain's amino acid to allow transfer to the PCP, or peptide carrying protein, region. The activated amino acid is transferred to a cysteine residue in the PCP region, which anchors the amino acid and prepares the amino acid to be added to the polypeptide. The C, or condensation, region attaches the amino acid to the polypeptide. In addition, modules 2, 4, and 5 have E regions that epimerize (switch the stereochemistry) of the added amino acid to produce the correct configuration. Module 7, the last module, has an X and TE region. The X region is responsible for recruiting several of the tailoring enzymes that will perform the necessary reactions (halogenation, glycosylation, methylation, oxidative cross-linking, and hydroxylations) to produce chloroeremomycin. Finally, the TE, or thioesterase, region releases chloroeremomycin from the NRPS complex.
Post-peptide modifications
The modification required to biosynthesize mature chloroeremomycin include: oxidative cross-linking of aromatic rings, hydroxylation and chlorination of the two Tyr residues, methylation of Leu, and glycosylation at aa4 and aa6.
The oxidative crosslinks are catalyzed by enzymes OxyA-C. The glycosylations are catalyzed by enzymes GtfA-C (coded by Orf11-13 respectively). The chlorinations are performed by enzymes encoded by Orf10 and 18.
Total synthesis
There is no reported total synthesis of chloroeremomycin, although there are several total syntheses of vancomycin. The structures of vancomycin and chloroeremomycin are very similar, differing only in the glycosylation sites. Vancomycin is glycosylated at aa4 with a (2-beta1)-Glc-vancosamine disaccharide. As mentioned above, chloroeremomycin is glycosylated at aa4 with a (2-beta1)-Glc-epivancosamine disaccharide and at aa6 with a beta1-epivancosamine saccharide.
Pharmacology and chemistry
See also
Glycorandomization
Teixobactin
References
Glycopeptide antibiotics
Halogen-containing natural products
Total synthesis
Drugs developed by Eli Lilly and Company | Chloroeremomycin | [
"Chemistry"
] | 1,383 | [
"Total synthesis",
"Glycopeptide antibiotics",
"Chemical synthesis",
"Glycopeptides"
] |
57,655,202 | https://en.wikipedia.org/wiki/San%20Thang | Thang Hoa San (, ; born 28 August 1954) is an Australian chemist of Chinese-Vietnamese background.
Background
Thang was born in Saigon in 1954 to Chinese parents who migrated to Vietnam in the 1930s. He completed his Bachelor of Science at Saigon University in 1976, and worked as a chemist at SINCO, a sewing machine manufacturer. In 1979, Thang left Vietnam as a refugee from the Vietnam War, and spent five months in a refugee camp in Malaysia before arriving in Brisbane, Australia later in the year. He enrolled at Griffith University where he completed an Honours degree in chemistry and a PhD in organic chemistry.
In 1986, Thang joined the CSIRO, the Australian government's scientific agency. In 1987, he left to join ICI Australia, but returned to CSIRO in 1990. In September 2014, research by Thomson Reuters for their citation laureate prize named Thang as one of a trio of CSIRO scientists (together with Ezio Rizzardo and Graeme Moad) most likely to be contenders for the Nobel Prize in Chemistry for their work in co-developing the reversible addition−fragmentation chain-transfer polymerization (RAFT) process. The three had shared the ATSE Clunies-Ross Award earlier that year. However, in December that year, Thang revealed that he had been laid off by the organisation in September, but had continued to work there unpaid in an honorary position. He later worked as a professor for Beijing University of Chemical Technology, and in May 2015, joined Monash University as a professor of chemistry and was elected as a Fellow of the Australian Academy of Science.
References
1954 births
Living people
21st-century Australian chemists
Australian chemists
Polymer scientists and engineers
Vietnamese scientists
CSIRO people
Griffith University alumni
Academic staff of Monash University
Companions of the Order of Australia
Fellows of the Australian Academy of Science
Fellows of the Australian Academy of Technological Sciences and Engineering
Vietnamese emigrants to Australia
Vietnamese refugees | San Thang | [
"Chemistry",
"Materials_science"
] | 391 | [
"Polymer scientists and engineers",
"Physical chemists",
"Polymer chemistry"
] |
57,655,611 | https://en.wikipedia.org/wiki/AmphibiaWeb | AmphibiaWeb is an American non-profit website that provides information about amphibians. It is run by a group of universities working with the California Academy of Sciences: San Francisco State University, the University of California at Berkeley, University of Florida at Gainesville, and University of Texas at Austin.
AmphibiaWeb's goal is to provide a single page for every species of amphibian in the world so research scientists, citizen scientists and conservationists can collaborate. It added its 7000th animal in 2012, a glass frog from Peru. As of 2022, it hosted more than 8,400 species located worldwide.
Beginning
Scientist David Wake founded AmphibiaWeb in 2000. Wake had been inspired by the decline of amphibian populations across the world. He founded it at the Digital Library Project at the University of California at Berkeley in 2000. Wake came to consider AmphibiaWeb part of his legacy.
Uses
AmphibiaWeb provides information to the IUCN, CalPhotos, Encyclopedia of Life and iNaturalist, and the database is cited in scientific publications.
References
Scientific organizations based in the United States
Science websites
Biodiversity databases
Online taxonomy databases
2000 establishments in California
Herpetology | AmphibiaWeb | [
"Biology",
"Environmental_science"
] | 249 | [
"Biodiversity databases",
"Environmental science databases",
"Biodiversity"
] |
57,655,715 | https://en.wikipedia.org/wiki/Hardware%20watermarking | Hardware watermarking, also known as IP core watermarking is the process of embedding covert marks as design attributes inside a hardware or IP core design itself. Hardware Watermarking can represent watermarking of either DSP Cores (widely used in consumer electronics devices) or combinational/sequential circuits. Both forms of Hardware Watermarking are very popular. In DSP Core Watermarking a secret mark is embedded within the logic elements of the DSP Core itself. DSP
Core Watermark usually implants this secret mark in the form of a robust signature either in the RTL design or during High Level Synthesis (HLS) design. The watermarking process of a DSP Core leverages on the High Level Synthesis framework and implants a secret mark in one (or more) of the high level synthesis phases such as scheduling, allocation and binding. DSP Core Watermarking is performed to protect a DSP core from hardware threats such as IP piracy, forgery and false claim of ownership. Some examples of DSP cores are FIR filter, IIR filter, FFT, DFT, JPEG, HWT etc. Few of the most important properties of a DSP core watermarking process are as follows:
(a) Low embedding cost
(b) Secret mark
(c) Low creation time
(d) Strong tamper tolerance
(e) Fault tolerance.
Process of hardware watermarking
Hardware or IP core watermarking in the context of DSP/Multimedia Cores are significantly different from watermarking of images/digital content. IP Cores are usually complex in size and nature and thus require highly sophisticated mechanisms to implant signatures within their design without disturbing the functionality. Any small change in the functionality of the IP core renders the hardware watermarking process futile. Such is the sensitivity of this process. Hardware Watermarking can be performed in two ways: (a) Single-phase watermarking, (b) Multi-phase watermarking.
Single-phase watermarking process
As the name suggests, in single-phase watermarking process the secret marks in the form of additional constraints are inserted in a particular phase of design abstraction level. Among the all design abstraction level of Electronic design automation process inserting watermarking constraints at High-level synthesis is always beneficial, especially where the applications have complex algorithms (such as Digital signal processor, Media processor). The register allocation phase of High-level synthesis is one of the popular locations where single-phase watermarking constraints are inserted. Mostly the secret marks are inserted in the register allocation phase using the concept of Graph coloring, where each additional constraint is added as an additional edge of the graph. Moreover, the additional constraints are mapped with an encoded variable for providing another layer of security. In binary encoding process the signature is provided in the form of 0 and 1; where each digit indicates a decoded constraints. In multi-variable encoding process the signature is provided in the form of four different variables viz. 'i', 'T', 'I', '!'.
Multi-phase watermarking process
As the name suggests, in the multi-phase watermarking process the additional constraints are inserted in multiple phases of a particular design abstraction level. For example, in High-level synthesis scheduling, hardware allocation and register allocation are used to insert a watermark. The main challenge of the multi-phase watermarking process is the dependence between additional constraints of multiple phases. In an ideal scenario, the watermarking constraints of each phase should not depend on each other. In other words, if somehow the watermarking constraints of a particular phase are tampered or removed, it should not impact the constraints of other phases. In multi-phase encoding process the signature is provided in the form of seven different variables viz. 'α', 'β', 'γ' 'i', 'T', 'I', '!'; where γ inserts watermark in scheduling phase, α and β insert watermark in hardware allocation phase, i, T, I, and ! insert watermark in the register allocation phase.
See also
Hardware obfuscation
Semiconductor intellectual property core
High-level synthesis
Electronic design automation
Graph coloring
References
Electronic design automation
Electronic engineering
Hardware acceleration | Hardware watermarking | [
"Technology",
"Engineering"
] | 870 | [
"Hardware acceleration",
"Computer engineering",
"Computer systems",
"Electronic engineering",
"Electrical engineering"
] |
57,655,879 | https://en.wikipedia.org/wiki/VS%20%28nerve%20agent%29 | VS is a nerve agent of the V-series. Its chemical structure is very similar to the VX nerve agent, but the methyl group on the phosphorus atom is replaced by an ethyl group.
See also
VX (nerve agent)
References
V-series nerve agents
Acetylcholinesterase inhibitors
Diisopropylamino compounds
Ethyl esters | VS (nerve agent) | [
"Chemistry"
] | 74 | [
"Organic compounds",
"Organic compound stubs",
"Organic chemistry stubs"
] |
57,656,729 | https://en.wikipedia.org/wiki/MRS%20Bulletin | MRS Bulletin is published by the Materials Research Society in partnership with Springer Nature. It was established in 1974 as the Materials Research Society Newsletter. There was a year gap in 1981, and then in 1982, it came back as MRS Bulletin.
The current editor is Gopal R. Rao (2011–present). The previous editor was Elizabeth Fleischer (1991 to 2011).
Abstracting and indexing
The journal is abstracted and indexed in
Current Contents Engineering, Technology, and Applied Sciences
Current Contents Physical Chemical and Earth Sciences
SciSearch online database
Research Alert
Science Citation Index
Materials Science Citation Index
Scopus
According to Journal Citation Reports, the journal has a 2020 impact factor of 6.578.
References
Materials science journals
Cambridge University Press academic journals
English-language journals
Academic journals associated with learned and professional societies
Monthly journals
Academic journals established in 1974 | MRS Bulletin | [
"Materials_science",
"Engineering"
] | 170 | [
"Materials science journals",
"Materials science"
] |
57,657,930 | https://en.wikipedia.org/wiki/Ocean%20Nuclear | Ocean Nuclear () is a financial services provider for the nuclear energy industry. It provides capital market services for energy projects worldwide and has negotiated nuclear infrastructure projects in more than 20 countries.
Capital
Ocean Nuclear is currently raising to fund infrastructure projects in nuclear energy.
Global Nuclear Investment Summit
Ocean Nuclear co-organises the Global Nuclear Investment Summit (GNIS). The first was held in Beijing in January 2018. The second took place in London in June 2018, in partnership with the Financial Times.
References
Companies based in Shenzhen
Financial services companies of China
Nuclear industry organizations
Nuclear technology | Ocean Nuclear | [
"Physics",
"Engineering"
] | 114 | [
"Nuclear technology",
"Nuclear industry organizations",
"Nuclear organizations",
"Nuclear physics"
] |
57,658,870 | https://en.wikipedia.org/wiki/Grimpoteuthis%20plena | Grimpoteuthis plena is known from only one specimen, which cannot be easily separated from other species of Grimpoteuthis in the Atlantic Ocean. This species may be a senior synonym to Grimpoteuthis wuelkeri (but has fewer suckers), but the poor condition of the only known specimen (the holotype) hinders comparison. Grimpoteuthis plena, along with G. wuelkeri and G. discoveryi, may all be junior synonyms of G. umbellata, but this also cannot be resolved given the poor condition of the only known G. umbellata specimen.
Description and habitat
Grimpoteuthis plena was found in the northwestern Atlantic Ocean, at 1,963 meters deep. Like other members of Grimpoteuthidae, it could be demersal or bentho-pelagic. Specifically, the single known specimen of G. plena was collected at a latitude of 37º 35’N and a longitude of 71º 18’W in the northwestern Atlantic Ocean, with other species of the same genus being found nearby. The single G. plena specimen was found in the year 1880 by Verrill.
The specimen's mantle reached 57 millimeters long, and its total length reached 185 millimeters. Some of its arms were longer than the others, with between 55 and 60 suckers per arm (largest suckers 2.5 millimeters in diameter). The octopus' cirri are short. Its fins are each 32 millimeters long. The eyes are small: each is 12 millimeters in diameter.
References
Octopuses
Molluscs of the Atlantic Ocean
Cephalopods described in 1885
Species known from a single specimen | Grimpoteuthis plena | [
"Biology"
] | 356 | [
"Individual organisms",
"Species known from a single specimen"
] |
57,660,962 | https://en.wikipedia.org/wiki/GJ%201132 | GJ 1132 is a small red dwarf star away from Earth in the constellation Vela. In 2015, it was revealed to have a hot rocky Earth-sized planet orbiting it every 1.6 days. In 2018, a second planet and a potential third were revealed.
Planetary system
As of June 12, 2018, there are two confirmed exoplanets and one candidate exoplanet orbiting GJ 1132.
GJ 1132 b
GJ 1132 b is the innermost planet of the GJ 1132 system, as well as the smallest. It is very similar in size and mass to Earth, with a radius of 1.13 and a mass of 1.66 . It is slightly denser than Earth with 30% more surface gravity, meaning it has a rocky composition. Despite its physical similarities to Earth, it is considered too hot to be habitable, getting 19 times more sunlight due to its 1.6 day orbital period. , it remains unclear whether the planet has an atmosphere, with some studies finding evidence for an atmosphere, but others finding a flat, featureless spectrum that leaves the presence or absence of an atmosphere inconclusive.
GJ 1132 c
GJ 1132 c was reported by Bonfils and colleagues using the HARPS spectrograph on the ESO 3.6 m Telescope at the La Silla Observatory in Chile in June 2018. No transits of the planet were found, but it has a minimum mass of about 2.6 and gets 1.9 times the amount of sunlight as Earth with an equilibrium temperature of . It orbits outside the inner limit of GJ 1132's habitable zone (which ends at 1.6 times the stellar flux of Earth), but because the exact characteristics of the planet's atmosphere are unknown, it has been mentioned that it could still be potentially habitable. However, with a lack of transits, determining its atmospheric characteristics will be extremely difficult.
GJ 1132 d
An unconfirmed cold super-Earth candidate was also detected, with a minimum mass of about 8.4 and a low equilibrium temperature of . It has been designated GJ 1132 (d) with parenthesis because it is not considered a confirmed planet. Despite the signal having a false alarm probability of less than 0.01%, comparable to GJ 1132 b and c, it is close to the period of the star's magnetic cycle.
See also
Wolf 1061
References
M-type main-sequence stars
Planetary systems with two confirmed planets
Vela (constellation)
1132 | GJ 1132 | [
"Astronomy"
] | 520 | [
"Vela (constellation)",
"Constellations"
] |
57,661,521 | https://en.wikipedia.org/wiki/NGC%203316 | NGC 3316 is a barred lenticular galaxy located about 190 million light-years away in the constellation Hydra. The galaxy was discovered by astronomer John Herschel on March 26, 1835. NGC 3316 is a member of the Hydra Cluster, and appears to have a small companion galaxy known as HCC 15.
See also
List of NGC objects (3001–4000)
References
External links
Hydra Cluster
Hydra (constellation)
Barred lenticular galaxies
3316
031571
Astronomical objects discovered in 1835
Discoveries by John Herschel | NGC 3316 | [
"Astronomy"
] | 105 | [
"Hydra (constellation)",
"Constellations"
] |
57,662,947 | https://en.wikipedia.org/wiki/Rocketry%20SA | Rocketry SA is the official voice and controlling body for all aspects of non-commercial and non-governmental rocketry in South Africa. The organization is registered as a non profit organization in South Africa. Rocketry SA promotes model rocketry, high-power rocketry, amateur rocketry, and aerospace modelling.
History
The organization was established in 2003, under the name South African Amateur Space Association (SAASA).
During the 2013 Annual General Meeting of the Association, members voted in favour of a name change. Due to practical reasons, however, and in line with the legal requirements of registering a non-profit organization in South Africa, the name was only officially changed in 2017 to "Rocketry SA".
Organizational structure
Rocketry SA functions as a member-based, non-profit organization.
In line with South African law, the Organization appoints a CEO (chief executive office), supported by an EXCO (Executive committee).
Rocketry SA co-exists under the government-mandated South African National Space Agency (SANSA), which resides under the Department of Science and Technology (DSC), which in turn reports to the Minister of Science and Technology.
Membership
Rocketry SA membership is open to any with a keen interest in promoting rocketry.
Rocketry SA maintains a database of all registered rocketeers. This database includes information like certification level, which is used to determine which motors may be purchased by the member.
External links
Official website
References
Rocketry
Space program of South Africa | Rocketry SA | [
"Engineering"
] | 301 | [
"Rocketry",
"Aerospace engineering"
] |
57,662,978 | https://en.wikipedia.org/wiki/ScanPyramids | The ScanPyramids mission is an Egyptian-International project designed and led by Cairo University and the French HIP Institute (Heritage Innovation Preservation). This project aims at scanning Old Kingdom Egyptian Pyramids (Khufu, Khafre, the Bent and the Red) to detect the presence of unknown internal voids and structures.
The project, launched in October 2015, combines several non-invasive and non-destructive techniques which may help to get a better understanding of their structure and their construction processes and techniques. The team was using Infrared thermography, muon tomography, 3D simulation and reconstruction techniques.
ScanPyramids is an interdisciplinary project mixing art, science and technology. On November 2, 2017, the ScanPyramids team announced, through a publication in Nature, its third discovery in the Great Pyramid, a "plane-sized" previously unknown void named the "ScanPyramids Big Void".
Discoveries
2016
On October 15, 2016, ScanPyramids confirmed their first unknown void discoveries thanks to muon tomography in the Great Pyramid. A previously unknown cavity was confirmed on the North-Eastern Edge, roughly at high with similar void volume characteristics as a known "cave" located at on the same edge.
A second void was discovered behind the chevrons area of Khufu's North Face above the Descending Corridor (referred to as "SP-NFC" in papers). This area was investigated after thermal anomalies observation that led the team to position muon emulsion plates in the Descending Corridor. This void was further investigated during 2017 to provide more information about its shape, size, and exact position.
2017
In 2017 more muon-sensitive emulsion plates were positioned in the descending corridor and in Al-Mamun's tunnel. The void behind the chevrons could be confirmed through different points of view and its characteristics refined. Named "ScanPyramids North-Face Corridor" (SP-NFC), this void is located between from the Great Pyramid's ground level, between from the North Face. It could be horizontal or sloping upwards and it has a corridor-like shape.
ScanPyramids Big Void (SP-BV)
On November 2, 2017, the ScanPyramids team published its third discovery in Nature, which was named "ScanPyramids Big Void", or "SP-BV" for short. It describes a newly discovered huge void in a circumscribed area above the Grand Gallery. It is estimated to have a length of at least and a similar cross-section as the Grand Gallery. The ScanPyramids Big Void has been observed by three teams of physicists from different points of view (2 points of view in the Queen's Chamber and from outside in front of the North Face).
Three scientific institutions specializing in particle physics have worked independently and each one used a different and complementary muography technique:
Nagoya University, Japan: Nuclear emulsion plates in the Queen's Chamber under the leadership of Professor Morishima Kunihiro
High Energy Accelerator Research Organization (KEK), Japan: Scintillator hodoscope in the Queen's Chamber
Alternative Energies and Atomic Energy Commission (CEA), France: Muon telescopes with gas detectors positioned outside in front of the Great Pyramid's North Face.
Like the work done on the "ScanPyramids North Face Corridor", more muography observations, from new viewpoints, need to be conducted in order to better determine the Big Void's shape, so that functional inferences can be drawn.
As long the exact layout and function of the void is still unknown, the scientists have been cautious about using architectural nomenclature.
North Facing Corridor (SP-NFC)
In March 2023, the team published its finding of the North Facing Corridor (NFC) behind the original entrance; the void is called "SP-NFC" (ScanPyramids - North Face Corridor) in the paper.
Reactions
Egyptologists
On November 2, 2017, the Egyptologist Zahi Hawass told the New York Times: "They found nothing...This paper offers nothing to Egyptology. Zero."
On November 3, 2017, Egypt's Ministry of Tourism and Antiquities said in a statement, "The existence of several void spaces inside the pyramid is not a new thing. Egyptologists and scholars knew about it several years ago," adding, "the ministry sees that the ScanPyramid team should not have rushed to publish their findings in media at that stage of their research because it requires more research and it is too early to say that there was a new discovery."
On November 4, Khaled al-Anany, Egyptian Minister of Antiquities said, during a press conference, that the void space found inside the Great Pyramid of Khufu by the ScanPyramids project is a new revelation that brought the world's attention to Egypt. He added "What was discovered is new and larger than the known cavities, and we'll continue in our scientific steps".
Other Egyptologists have welcomed the discovery. Yukinori Kawae told National Geographic "This is definitely the discovery of the century...There have been many hypotheses about the pyramid, but no one even imagined that such a big void is located above the Grand Gallery."
Peter der Manuelian, from Harvard University, said that "This is an exciting new discovery, and potentially a major contribution to our knowledge about the Great Pyramid."
Physicists
Lee Thompson, an expert in particle physics at the University of Sheffield (UK) told Science: "The scientists have "seen" the void using three different muon detectors in three independent experiments, which makes their finding very robust." Christopher Morris, physicist at Los Alamos National Laboratory called the findings "pretty amazing". Jerry Anderson who worked on Khafre's Pyramid and was a member of the team of Luis Walter Alvarez, the first scientist to use muography inside a pyramid in 1965, said to Los Angeles Times, with a laugh: "I am very excited and very pleased,...I wish we had worked in the Great Pyramid, now that I look back on it".
International media
This discovery has been featured in many international media as one of the top discoveries of the year 2017 (NBC News, Euronews, Physics World, Science News, Global News, Gizmodo, Business Insider, Altmetric, Egypt Today, NBC, MSN News, Le Monde, CTV, The Franklin Institute, Radio Canada, Sciences et Avenir, RTÉ, PBS, Yahoo, La Vanguardia, France Info).
References
Egyptology
Particle physics | ScanPyramids | [
"Physics"
] | 1,358 | [
"Particle physics"
] |
57,663,216 | https://en.wikipedia.org/wiki/Abstract%20differential%20equation | In mathematics, an abstract differential equation is a differential equation in which the unknown function and its derivatives take values in some generic abstract space (a Hilbert space, a Banach space, etc.). Equations of this kind arise e.g. in the study of partial differential equations: if to one of the variables is given a privileged position (e.g. time, in heat or wave equations) and all the others are put together, an ordinary "differential" equation with respect to the variable which was put in evidence is obtained. Adding boundary conditions can often be translated in terms of considering solutions in some convenient function spaces.
The classical abstract differential equation which is most frequently encountered is the equation
where the unknown function belongs to some function space , and is an operator (usually a linear operator) acting on this space. An exhaustive treatment of the homogeneous () case with a constant operator is given by the theory of C0-semigroups. Very often, the study of other abstract differential equations amounts (by e.g. reduction to a set of equations of the first order) to the study of this equation.
The theory of abstract differential equations has been founded by Einar Hille in several papers and in his book Functional Analysis and Semi-Groups. Other main contributors were Kōsaku Yosida, Ralph Phillips, Isao Miyadera, and Selim Grigorievich Krein.
Abstract Cauchy problem
Definition
Let and be two linear operators, with domains and , acting in a Banach space . A function is said to have strong derivative (or to be Frechet differentiable or simply differentiable) at the point if there exists an element such that
and its derivative is .
A solution of the equation
is a function such that:
the strong derivative exists and for any such , and
the previous equality holds .
The Cauchy problem consists in finding a solution of the equation, satisfying the initial condition .
Well posedness
According to the definition of well-posed problem by Hadamard, the Cauchy problem is said to be well posed (or correct) on if:
for any it has a unique solution, and
this solution depends continuously on the initial data in the sense that if (), then for the corresponding solution at every
A well posed Cauchy problem is said to be uniformly well posed if implies uniformly in on each finite interval .
Semigroup of operators associated to a Cauchy problem
To an abstract Cauchy problem one can associate a semigroup of operators , i.e. a family of bounded linear operators depending on a parameter () such that
Consider the operator which assigns to the element the value of the solution of the Cauchy problem () at the moment of time . If the Cauchy problem is well posed, then the operator is defined on and forms a semigroup.
Additionally, if is dense in , the operator can be extended to a bounded linear operator defined on the entire space . In this case one can associate to any the function , for any . Such a function is called generalized solution of the Cauchy problem.
If is dense in and the Cauchy problem is uniformly well posed, then the associated semigroup is a C0-semigroup in .
Conversely, if is the infinitesimal generator of a C0-semigroup , then the Cauchy problem
is uniformly well posed and the solution is given by
Nonhomogeneous problem
The Cauchy problem
with , is called nonhomogeneous when . The following theorem gives some sufficient conditions for the existence of the solution:
Theorem. If is an infinitesimal generator of a C0-semigroup and is continuously differentiable, then the function
is the unique solution to the (abstract) nonhomogeneous Cauchy problem.
The integral on the right-hand side as to be intended as a Bochner integral.
Time-dependent problem
The problem of finding a solution to the initial value problem
where the unknown is a function , is given and, for each , is a given, closed, linear operator in with domain , independent of and dense in , is called time-dependent Cauchy problem.
An operator valued function with values in (the space of all bounded linear operators from to ), defined and strongly continuous jointly in for , is called a fundamental solution of the time-dependent problem if:
the partial derivative exists in the strong topology of , belongs to for , and is strongly continuous in for ;
the range of is in ;
and
.
is also called evolution operator, propagator, solution operator or Green's function.
A function is called a mild solution of the time-dependent problem if it admits the integral representation
There are various known sufficient conditions for the existence of the evolution operator . In practically all cases considered in the literature is assumed to be the infinitesimal generator of a C0-semigroup on . Roughly speaking, if is the infinitesimal generator of a contraction semigroup the equation is said to be of hyperbolic type; if is the infinitesimal generator of an analytic semigroup the equation is said to be of parabolic type.
Non linear problem
The problem of finding a solution to either
where is given, or
where is a nonlinear operator with domain , is called nonlinear Cauchy problem.
See also
Cauchy problem
C0-semigroup
References
Functional analysis | Abstract differential equation | [
"Mathematics"
] | 1,083 | [
"Functional analysis",
"Mathematical objects",
"Functions and mappings",
"Mathematical relations"
] |
57,663,296 | https://en.wikipedia.org/wiki/Jewell%20water%20filter | A Jewell water filter was a system of sand filters for filtering and treating water for drinking purposes that made use of gravity to allow water to percolate through a column of sand inside cylindrical cisterns that was widely used in the early twentieth century. They are named after Omar Hestrian Jewell (1 July 1842 - 19 June 1931) established Jewell Pure Water Company in Chicago in 1890 and managed later by two of his sons. Jewell water filters were used in many city water supply systems across the world and modified versions continue to be in use.
History
Slow sand filters were introduced at a point when the nature of disease causing organisms in typhoid and cholera had been established. Omar Jewell was a mechanical engineer who designed farm equipment and he took an interest in solving some of the problems involved in the filtration of water and established the O.H.Jewell Filter Company and was financed by Chicago-based waterwork dealers James B. Clow and Sons. Omar's son William H. Jewell graduated in 1887 from the College of Pharmacy, University of Illinois and served as a chemist in the company. Another son, Ira worked for a while with the company but sold his stock in 1900 to start a breakaway company I.H. Jewell Filter Company.
The first Jewell filters were built for use at Rock Island, Illinois in 1891. Jewell filters evolved over time to substitute open sand bed filters which had problems in the United States: freezing in winter and algal growth in summer introducing an odour to the water. Over time Omar and his sons owned several patents in water filtration, nearly 50 patents between 1888 and 1900, including novel systems for combining filtering and chlorination. By 1896 nearly 21 plants in the United States of America used Jewell filters. In 1898 the O.H.Jewell Filter Company settled a patent infringement claim over a coagulation process patented by Isaiah Smith Hyatt, brother of John Wesley Hyatt, in 1884 and owned by the New York Filter Manufacturing Company. Other filter companies came up during the period and there were numerous patent litigations and company mergers with Jewell merging with the New York Filter Manufacturing Company in 1900 to become the single major New York Continental Jewell Filtration Company. The resulting company owned the licenses to most of the valuable patents of the day and by 1909 they had nearly 360 plants in operation. Several were built in far away places like India with the largest being in Kolar at Bethamangala with a capacity of 2,000,000 gallons per day. The one in Warsaw was the largest in Europe in its time.
An outbreak of typhoid during the 1890s in the city of Pittsburgh led to calls for improved sanitation and improvements in the quality of drinking water supply. Pittsburgh Filtration Commission was established in June 1896 and it recommended in 1899 a slow-sand filtration system. Once this became operational, the cases of typhoid were greatly reduced. The Filtration commission wrote to several companies but only two agreed to enter the tests. These were the Cumberland manufacturing company and the Morison-Jewell Filtration Company and the committee experimented with a Warren filter and a Jewell filter. Jewell filters underwent further bacteriological tests in Alexandria and Berlin and their approval led to their wider adoption in numerous town water supplies in the early 1900s. The British troops at Alexandria brought down typhoid deaths to zero by 1905 with water treatments that included the use of Jewell filters. Jewell filters became commonplace in British Indian military towns in the plains after around 1910 and their construction had been standardized in engineering manuals.
Construction and working
Jewell filters, unlike their predecessors, open sand filters, were housed indoors and included mechanical action to turn and wash the sand with their key advantages being their ability to work in winter and reduce bacterial counts. The water from a river or lake is first passed through sedimentation beds where a coagulant such as alum is added. The water then goes into the sand bed within cylinders of the Jewell filters and the coagulant forms a film on top of it. The sand beds are cleaned by stirring them with rotary arms and washing with water pumped at pressure from below. The Warren filter also had a similar system for washing sand. The design to carry away the wash effluent however differed between the Warren and Jewell filters. The system also included automatic control the flow of water inflow and devices to control the addition of chemicals such as lime and iron. The company later produced variations that used water under pressure than to merely rely on gravity.
References
External links
Catalog from 1897
New York Continental Jewell Filtration Company 1913
Patents related to the company and the filters
Water treatment | Jewell water filter | [
"Chemistry",
"Engineering",
"Environmental_science"
] | 960 | [
"Water treatment",
"Environmental engineering",
"Water technology",
"Water pollution"
] |
57,664,844 | https://en.wikipedia.org/wiki/G%C3%B6sta%20Ekspong | Anders Gösta Ekspong (born Anders Gösta Carlson on 24 February 1922 in Skogstorp, Husby-Rekarne Township, Södermanland County, – 24 February 2017) was a Swedish physicist and former professor at Stockholm University. His main area of work was atomic physics. Ekspong defended his thesis for doctorate in 1955 at Uppsala University with a dissertation on Cosmic Radiation under supervision of Axel E. Lindh.
Ekspong is considered to be one of the Swedish pioneers in the involvement of the particle physics laboratory at CERN. At CERN, he was chairman of the Emulsion Experiments Committee from the early 1960s as well as member of the Scientific Policy Committee (1969-1975), where he also spent two years as chairman (1972-1974). He made a significant contribution to the search strategies that would later be used in the search of the Higgs boson and participated in the technological development of DELPHI. Ekspong was elected as a member of the Royal Swedish Academy of Sciences in 1969. From 1975 to 1988 he was also a member of the Nobel Committee for Physics where he held the post of chairman between 1987 and 1988. During his career Ekspong published several scientific publications regarding subjects such as particle physics, astrophysics and nuclear physics, some together with researchers at the University of Bristol and the University of California. He is currently buried at Skogskyrkogården in Stockholm.
References
Uppsala University alumni
People associated with CERN
Swedish physicists
Particle physicists
Members of the Royal Swedish Academy of Sciences
1922 births
2017 deaths
Burials at Skogskyrkogården | Gösta Ekspong | [
"Physics"
] | 326 | [
"Particle physicists",
"Particle physics"
] |
44,297,134 | https://en.wikipedia.org/wiki/National%20Authority%20for%20Chemical%20Weapons%20Convention | National Authority for Chemical Weapons Convention or NACWC is an office in Cabinet Secretariat, Government of India, established on 29 April 1997 by a resolution of the Cabinet and was later accorded a statutory status through Chemical Weapons Convention Act, 2000.
References
Cabinet Secretariat of India
Chemical weapons demilitarization | National Authority for Chemical Weapons Convention | [
"Chemistry"
] | 60 | [
"Chemical weapons demilitarization",
"Chemical weapons"
] |
44,297,345 | https://en.wikipedia.org/wiki/List%20of%20largest%20nebulae | Below is a list of the largest known nebulae so far discovered, ordered by actual diameter. This list is prone to change because of inconsistencies between studies, the great distances of nebulae from our stellar neighborhood, and the constant refinement of technology and engineering.
Caveats
Nebulae have no standardized boundaries, so the measurements are subject to revision. Furthermore, scientists are still defining the features and parameters of nebulae. Because of these rapid developments and adjustments, this list may be unreliable.
Lyman alpha nebulae around quasars can have sizes between 15 kpc and 460 kpc. Especially large Enormous Lyα nebula (ELAN) can have large sizes of ≳100 kpc. Farina et al. 2019 table 5 has an extensive compilation of Lyman alpha nebulae around quasars. For now this list contains only the largest ELANs, with sizes larger than 300 kpc.
List
See also
List of largest cosmic structures
List of largest known stars
List of largest planets
List of most massive stars
List of most massive black holes
List of largest galaxies
Notes
References
Sources
Largest
Nebulae, Largest | List of largest nebulae | [
"Astronomy"
] | 224 | [
"Astronomy-related lists",
"Lists of superlatives in astronomy"
] |
44,297,819 | https://en.wikipedia.org/wiki/Hive%20UI | Hive (stylized as HIVE) is a custom ROM developed by Xolo and is built on the Android operating system v 4.4.4 (KitKat). Hive is exclusive to Xolo devices and is not licensed to third-parties.
Hive was designed by Xolo's software design team at Bangalore. Users can interact with the development team and share ideas for new features. The Hive Development Team aims to release over-the-air updates with new features or bug fixes every fortnight.
The first Xolo device (8X-1000) with Hive was launched in August 2014.
Smartphones running Hive UI
Xolo 8X-1000
Xolo Omega 5.0
Xolo Omega 5.5
Xolo Black
Xolo Black 1X
See also
List of custom Android firmware
References
External links
Custom Android firmware
Embedded Linux
Mobile Linux | Hive UI | [
"Technology"
] | 172 | [
"Mobile software stubs",
"Mobile technology stubs"
] |
44,298,007 | https://en.wikipedia.org/wiki/Shield%20lichen | Shield lichen is the common name for lichens in either the genus Heterodermia or genus Parmelia.
References
Fungus common names
Lichenology | Shield lichen | [
"Biology"
] | 34 | [
"Lichenology",
"Fungus common names",
"Fungi",
"Common names of organisms"
] |
44,298,290 | https://en.wikipedia.org/wiki/Discovery%20and%20development%20of%20neuraminidase%20inhibitors | Neuraminidase inhibitors inhibit enzymatic activity of the enzyme neuraminidase (sialidase). These type of inhibitors have been introduced as anti-influenza drugs as they prevent the virus from exiting infected cells and thus stop further spreading of the virus. Neuraminidase inhibitors for human neuraminidase (hNEU) have the potential to be useful drugs as the enzyme plays a role in several signaling pathways in cells and is implicated in diseases such as diabetes and cancer.
History
The first neuraminidase Inhibitors (NAIs) were synthesized in the 1960s by Edmond et al., through an attempt to understand the catalytic mechanism of the neuraminidase enzyme. They discovered that N-substituted oxamic acids had enzyme inhibitory properties. Then it was found that the synthetic compound 2-deoxy-2,3-didehydro-N-acetylneuraminic acid (Neu5Ac2en or DANA) which is an analogue of N-acetylneuraminic acid (Neu5Ac), inhibits the release of virus progeny in tissue culture but no antiviral activity in animals was detected.
In the early 1990s, the determination of biological crystal structure of influenza virus surface protein led to the discovery of the active site and provided the opportunities to discover and design new and specific inhibitors.
Influenza virus
The Influenza virus is an RNA virus that is divided into three serological types: A, B and C. Hemagglutinin (HA) and neuraminidase (NA) are two important glycoproteins on influenza virus membranes. The hemagglutinin is a sialic acid receptor-binding molecule and mediates entry of the virus into the host cell, while neuraminidase cleaves cellular-receptor sialic acid to form new particles. Neuraminidase is an exoglycosidase that destroys the hemagglutinin receptor by cleaving the α(2,6)- or α(2,3)-ketosidic linkage that exists between a terminal sialic acid and a sugar residue of the Neu5Ac containing receptor on the surface of host cells. This helps the spread of the infection by preventing self-aggregation of new viruses at the cell surface and possible immobilisation in the mucin by hemagglutinin (HA) during virus replication. The virus will then be released from the host cells and will subsequently infect other cells. Neuraminidase also helps the invasion of the virus in the upper respiratory tract, possibly by cleaving sialic acid molecules on mucin of epithelial cells. Neuraminidase is found in influenza viruses of types A and B. Neuraminidase has roles in the infection, replication and delivery of Influenza virus A and B. Type C Influenza virus expresses the enzyme esterase instead of neuraminidase.
The substrate
N-acetylneuraminic acid (Neu5Ac) is one of the two most common sialic acid in mammals. It is a monosaccharide with a backbone of 9 carbons. It is usually attached to glycoproteins or gangliosides on a terminal end via α(2,3), α(2,6), and α(2,8) linkage.
Neuraminidase is an enzyme which hydrolyses that bond to produce a free neuraminic acid and a glycoprotein or a sugar chain. Influenza virus will bind via the hemagglutinin protein on these sialic acid attached glycoproteins on the cell membrane.
Mechanism of action
Mechanism of enzyme catalysis
The mechanism of NA has been shown to proceed with the retention of configuration which means it preserves the absolute configuration on the atom in the stereocenter. There are four steps of catalytic pathways. In the first step, the binding step, the carboxylate group changes from the axial position into the pseudo-equatorial position. The second step is the proton donation from water molecule and formation of the endocyclic sialosyl cation transition-state intermediate. Step three involves nucleophilic attack of tyrosine on the sialosyl cation. The fourth step is the formation and release of Neu5Ac. A similar mechanism has been proposed by Janakiraman et al. where the double bond of Neu5Ac2en forces the pyranose of sugar ring into a planar structure were resembled the transition-state structure.
Mechanism of inhibition
There are two types of neuraminidase inhibitors commonly available for treatment and prophylaxis of influenza infections: Zanamivir and Oseltamivir. They interfere with the release of progeny virions from infected host cells, prevent infection process of new host cells and stop spread of infection in respiratory tract by mimicking natural substrate and fitting into active site of neuraminidase enzyme. They interrupt the detachment of progeny virions. Viral replication rate is then reduced and that allows human immune system to destroy the remaining viruses.
Development
Binding site
Viral neuraminidase
Influenza virus neuraminidase (vNEU) consists of 4 co-planar roughly spherical subunits predominantly made of β-sheets, characterized as a 6-fold β-propeller and a hydrophobic region embedded in the virus’ membrane. The active site is located near the middle of the pseudo-symmetric sphere. Influenza virus neuraminidase only cleaves terminal Neu5Ac residues. X-ray crystallography has shown a distorted half-chair arrangement of the Neu5Ac substrate in the active site. This distorted structure forms a sialosyl cation after the release of the aglycon and is then trapped in the active site by a nucleophilic attack of the tyrosine residue. The orientation of the substrate in the active site is facilitated mainly by three strain-preserved Arginine residues binding the C1 acid group with salt bridges. Furthermore, the active site consists of eight other highly conserved amino acid-residues that make direct contact to the substrate or its derivatives. Including a glutamic acid residue binding the C7 and C9 alcohol groups on the glycerol side-chain (at C6) with hydrogen bonds and several hydrophobic residues correlating with the methyl group on the C5 N-acetyl and the hydrophobic backbone of the glycerol.
Human Neuraminidase
Human neuraminidase (hNEU) shares many similar features with vNEU. The human genome has four different neuraminidase enzymes (NEU1, NEU2, NEU3, NEU4) and only one of them (NEU2) is not membrane-associated or in a membrane-complex and has been studied with X-ray crystallography. The three arginine residues that bind the C1 acid-group with salt bridges in vNEU are also present in hNEU. Active site topology and interactions with the substrate are very similar with the exception of the glycerol side chain which offers some strategic options in designing inhibitors targeting either vNEU or hNEU. In hNEU the glycerol hydroxyl-groups are bound via several tyrosine residues but in vNEU the main interaction is with a glutamic acid residue. These overall similarities have called for concerns over potential side effects from drugs targeting vNEU. Nevertheless, most of the well studied vNEU inhibitors have shown very little affinity for hNEU except for the influenza drug Zanamivir which is an effective inhibitor for hNEU2.
Viral neuraminidase inhibitors
2-deoxy-2,3-didehydro-N-acetylneuraminic acid (Neu5Ac2en) is a pan-selective inhibitor for neuraminidase. Neu5Ac2en is a dehydrogenated Neu5Ac and can be synthesized by the hNEU enzyme if Neu5Ac is in high enough concentration. Neu5Ac is also a mild inhibitor for the enzyme but as Neu5Ac2en is a transition-state analogue it is a much better inhibitor.
Zanamivir
In the beginning the X-ray crystallography did not have a very good resolution so the initial focus was on substrate derived inhibitors instead of structurally based. The Neu5Ac-derived 2-deoxy-α-D-N-acetylneuraminic acid (2-deoxy- α-Neu5Ac) was the first template used and also the first inhibitor tried in vivo in a mouse model of an influenza infection. The unsubstituted template showed minor effect. Another template Neu5Ac2en (DANA) was tried under same conditions and showed good in vivo effect. With new crystal structure images of the enzyme and Neu5Ac complex emerging and Neu5Ac2en confirmed as an in vivo inhibitor, the focus was on making structure based DANA derivatives. With better X-ray crystal structure a number of important residues in the active site were identified, specifically C4 hydroxyl group. Better effect was achieved by substituting the C4 hydroxyl group with a more basic group, for example an amino group. Further analysis showed that a larger group could be accommodated in the active site. 4-amino-4-deoxy-Neu5Ac2en and 4-deoxy-4-guanidino-Neu5Ac2en were synthesized and proved to be competitive inhibitors for viral neuraminidase and significantly inhibited both A and B influenza replication in vitro and in vivo. 4-deoxy-4-guanidino-Neu5Ac2en showed not only to be the better inhibitor but also showed considerable lower affinity for other isoforms of neuraminidase. For these reasons 4-deoxy-4-guanidino-Neu5Ac2en was selected as the main drug candidate under the name Zanamivir. High polar nature and rapid excretion contribute to the drugs low bioavailability and rapid elimination.
Oseltamivir
Multiple new inhibitors based on non-carbohydrate templates have been synthesized. With focus on positioning the double bond in the inhibitor to more closely resemble the transition state of the substrate and replacing the glycerol side chain with a lipophilic group on the basis of the hydrophobic backbone of the glycerol interacting with the protein lead to the discovery of GS 4071. GS 4071 is cyclohexene based and has 3-pentyl ether, found to be optimal, instead of the glycerol as the side chain. The GS 4071 inhibitor is more lipophilic than the predecessor Zanamivir but does not have more bioavailability. Oseltamivir, the ethyl ester of GS 4071 was produced as a prodrug and is actively converted to the active drug in vivo.
Peramivir
Peramivir is developed by structure-based drug design. After the influenza NA inhibitor activity of α/β-6-acetyl-amino-3,6-dideoxy -D-glycero-altro-2-nonulofuranosonic acid was reported by Yamamoto et al., the cyclopentane derivatives was designed with a guanidino group replacing C4-hydroxyl position of DANA in the active site, similar to Zanamivir. Babu et al. found that the addition of n-butyl side chain makes the compound fit better to the hydrophobic region of the enzyme. However, the conformation of the n-butyl group was found to be different when bound to influenza virus A from its conformation when bound to influenza virus B.
Since the compound processed similar binding interaction with active site of NA to zanamivir and due to the mutation in some zanamivir-resistance strains, the position of guanidino group was altered and the n-butyl group was replaced in order to change its active site interaction.
Structures of the Viral neuraminidase inhibitors in use
*Only Zanamivir and Oseltamivir are FDA approved. Peramivir is used in Japan and South Korea. Laninamivir is used in Japan only.
Recent development and design of analogues of viral inhibitors
New NA inhibitor analogues were synthesized, based on Zanamivir, Oseltamivir and Peramivir, with rational structure-based drug design and can be categorized into four groups.
Analogues of Zanamivir
Zanamivir analogues are designed to improve the therapeutic use. Replacing the carboxylate group at the C1 to phosphonate group led the drug to be more potent with high affinity to form ionic interaction with the active site. Additionally, the click-chemistry reaction was used to synthesize the C4-triazole-modified zanamivir analogue that shows inhibitory activity close to zanamivir. Laninamivir is designed by replacing C7 hydroxy moiety with small lipophilic group, -OCH3, which resulted in an excellent inhibitory activity. The C8 and C9 diol play an important role in the binding affinity with neuraminidase, prolonging the effect. The polymer scaffolds at the C7 position of zanamivir via an alkyl ether has gained more attention as this showed enhanced antiviral activity.
Analogues of Oseltamivir
The knowledge of transition state structure has been used to design oseltamivir analogues. For example, the triazole-containing carbocycles by Von Itzstein and Pinto group and the phosphonate analogue of oseltamivir has been reported to show stronger activity resulted from a pertinent binding mode of phosphonate with three Arginine residues in the active site.
,
Analogues of Peramivir
Peramivir is the cyclopentane derivative designed with a guanidino group replacing the C-4 hydroxyl group of Neu5Ac2en in the active site, with negatively charged carboxylate group and a n-butyl side chain. 1-ethylpropylamide, diethylamide, dipropylamide and 4-morpholinylamide groups all showed excellent inhibitory activity. Changing the cyclopentane ring to a pyrrolidine ring showed high inhibitory activity as well.
Analogues of Benzoic acid
The replacement of dihydropyran ring with a benzene ring increases the lipophilicity of a drug and makes the drug much more stable and more synthetically accessible. Based on the interaction of DANA and NA, the benzoic derivatives were synthesized. They have shown similar or better inhibitory activity compared to Neu5Ac.
Human neuraminidase inhibitors
Zanamivir and Oseltamivir have been tested as hNEU inhibitors. Only Zanamivir shows moderate inhibition activity for hNEU. Isoenzyme selective inhibitors could potentially be very important. At present there are limited studies for the hNEU substrate specificity. DANA is a pan-selective inhibitor for all hNEU isoenzymes, with a difference from 2 to 10 fold inhibition activity, most effective for hNEU3 and hNEU4. Several reports have tested DANA-derivatives as inhibitors for hNEU2 and hNEU3. Most derivatives showed reduced inhibition in vitro. However, N5-azidoacetate-C9-azido derivative of DANA showed improved inhibition for hNEU2 and hNEU3. These studies concluded that the active site in the enzymes could tolerate large modifications at C9 better than at N5. Testing of C9 amido derivatives of DANA showed hNEU1-selective inhibitors. These compounds showed more activity then DANA and only minor activity for hNEU3 with around 25-fold selectivity for hNEU1. These studies show that the glycerol side-chain pocket in the active site can potentially be manipulated in the design of isoenzyme selective inhibitors for hNEU. A combination of C4 and C7 modified DANA derivatives has been reported with moderate selectivity for hNEU2 and hNEU3. Finally C9-triazole derivatives of DANA containing an alkoxy group with a nanomolar activity against hNEU4 isoenzyme have been reported. With a 500-fold selectivity for hNEU4, this is the highest reported selectivity for a hNEU isoenzyme to date.
Usage
There are 2 subgroups of NA inhibitors that have been approved by regulatory authorities in the US and Europe, Zanamivir and Oseltamivir. Both are for the treatment and prevention of influenza. Furthermore, Peramivir and Laninamivir have been approved by regulatory authorities in some parts of Asia.
Laninamivir
Laninamivir is approved for the treatment of influenza under the tradename Inavir in Japan but it is still in clinical trial in the USA. Laninamivir is a long acting inhaled drug given as a prodrug (laninamivir octanoate). Laninamivir is given as a single dose and remains active for at least 5 days and up to 7 days.
Oseltamivir
Oseltamivir can be found under tradenames such as Agucort®, Antiflu, Fluvir, Fluhalt, GPO-A-Flu™, Omiflu, Rimivat, Virobin, Oseltamivir and Tamiflu®.
Oseltamivir is used for patients 1 year and older. It is given as one dose, twice a day for the treatment of influenza. In the prevention of influenza, oseltamivir is given as one dose, once a day for at least 10 days after contacting with an infected person and up to six months (during influenza epidemic). The most common side effects of Oseltamivir are headache and nausea (in adults) and vomiting, cough and nasal congestion (in children).
Peramivir
Peramivir is approved for the treatment of influenza under the tradenames Rapiacta® in Japan and Peramiflu in South Korea. In the US and elsewhere, peramivir is undergoing the late-phase clinical trial. Peramivir is used as intravenous and was used in the emergency treatment of 2009 H1N1 in select patients.
Zanamivir
Zanamivir can be found under tradenames such as Relenza™, Verenza and Z-Flu DPI.
Zanamivir is used for patients 5 years and older. It is given as one 10 mg dose, twice a day for the treatment of influenza. In the prevention of influenza, zanamivir is given as one 10 mg dose, once a day for 10 days after contacting with an infected person or up the 28 days (during influenza epidemic). The most common side effect of Zanamivir is reported to be rash.
Drug resistance
Currently, there are two classes of antiviral drugs approved for the treatment and prophylaxis of influenza infections. They are the adamantanes and NAIs. The adamantanes only work on influenza A so since 2010 WHO recommended the usage of NAIs for treatment and prophylaxis of influenza A and B infections. In contrast to adamantanes, NAIs are less toxic and less prone to promote drug-resistant influenza. Moreover, they are effective against all neuraminidase subtypes and all strains of influenza. After the influenza pandemic in 2009, there has been great concern about viral resistance to NAIs. Influenza viruses that have reduced sensitivity to NAIs often contain mutation that affect the shape of the NA catalytic site and therefore reduce the binding ability of the inhibitors. The catalytic site of the NA has eight functional residues ( R118, D151, R152, R224, E276, R292, R371, and Y406) surrounded by eleven framework residues (E119, R156, W178, S179, D198, I222, E227, H274, E277, N294, and E425).
Resistance to Oseltamivir
Oseltamivir has a large hydrophobic side chain and the NA must undergo rearrangement to form a pocket for drug binding by rotating aminoacid E276 and bond with R224. Mutations like H274Y, R292K and N294S that affect this forming could reduce the inhibitor's efficiency.
Resistance to Zanamivir
Resistance to zanamivir has been low for both seasonal and pandemic viruses compare to oseltamivir. Molecular structure of zanamivir has a guanidino group, this group interacts with the E119 residue in the active center pocket. Resistance to zanamivir can be because of mutations that effect binding affinity between the enzyme and the inhibitor. Mutation at the E119 residue has been shown to reduce the inhibitors efficiency in vitro.
Resistance to Peramivir
Peramivir has a guanidino group similar to zanamivir and a hydrophobic group similar to oseltamivir. Mutations that effect the efficiency of oseltamivir and zanamivir can also effect peramivir efficiency. Resistances to peramivir have been seen at the mutation of H274Y residue in vitro. One of these resistances is associated with cross-resistance to peramivir and oseltamivir. Peramivir is approved in Japan as Rapiacta and also available in South Korea as Peramiflu.
Resistance to Laninamivir
No laninamivir resistance has been reported. However it is a concern that resistance to laninamivir is similar to that of zanamivir because of the similarity in binding properties with the NA protein. Laninamivir octanoate (CS-8958), which is a prodrug of laninamivir (another inhaled NAI with long-acting properties), has also been approved in Japan and is commercially available under the name of Inavir (Daiichi Sankyo Company Ltd.
See also
Neuraminidase
Neuraminidase inhibitors
Influenza virus
Adamantane
References
neuraminidase inhibitors
Neuraminidase inhibitors | Discovery and development of neuraminidase inhibitors | [
"Chemistry",
"Biology"
] | 4,668 | [
"Neuraminidase inhibitors",
"Life sciences industry",
"Drug discovery",
"Medicinal chemistry",
"Glycobiology"
] |
44,298,369 | https://en.wikipedia.org/wiki/Discovery%20and%20development%20of%20beta2%20agonists | β2-adrenoceptor agonists are a group of drugs that act selectively on β2-receptors in the lungs causing bronchodilation. β2-agonists are used to treat asthma and COPD, diseases that cause obstruction in the airways. Prior to their discovery, the non-selective beta-agonist isoprenaline was used. The aim of the drug development through the years has been to minimise side effects, achieve selectivity and longer duration of action. The mechanism of action is well understood and has facilitated the development. The structure of the binding site and the nature of the binding is also well known, as is the structure activity relationship.
History
The β2-selective agonists were developed in the 20th century and are a very valuable class of drugs. In 1901 Jōkichi Takamine isolated the hormone adrenalin, also known as epinephrine. In 1890 adrenalin was first given to asthma patients orally. It had little or no effect because it is metabolized in the digestive tract and is deactivated. In 1930 epinephrine was for the first time given subcutaneously and was discovered to have a positive effect on asthma. When given subcutaneously adrenalin affects the whole body, giving various side effects and thus reducing the value of this treatment. The inhaled route was later tried and it gave much less adverse effects, but still had inconvenient side effects like fear, anxiety, restlessness, headache, dizziness and palpitation.
In 1940 isoproterenol (isoprenaline) was discovered. This compound had a similar effect as adrenalin but fewer side effects were found. In 1949 isoproterenol was used generally to treat asthma patients, given sublingually or inhaled. The first pressurized metered-dose inhaler was introduced in 1956. This was much more convenient for patients than the previously used squeeze-bulb inhalers. The pressurized metered-dose inhaler technique developed rapidly in the 1970s.
In 1967, it was shown that the β2-receptor was responsible for bronchodilation and this led to development of more selective drugs. In 1961 orciprenaline, a longer acting β2-agonist was found, but it was not as potent as isoproterenol. Orciprenaline does not have the catechol structure which was the reason for the longer action time. In the mid-1960s, albuterol or salbutamol was discovered, followed by tributalin and fenoterol a few years later. Albuterol and terbutaline gave fewer side effects, such as increased heart rate, than isoproterenol. The pharmaceutical company Glaxo discovered salmeterol, a long-acting β2-agonist that had bronchodilation activity for up to 12 hours. It was marketed in 1990. Formoterol, another long-acting β2-agonist, was marketed shortly after. This long duration of action made the treatment for severe asthma and COPD more convenient for the patients because it is inhaled twice a day.
In 2013 an extra long-acting β2-agonist, vilanterol, was marketed. Its duration of action lasts for 24 hours which should improve patients' compliance and make the treatment more convenient.
Clinical use
Asthma
β2-agonists are used to treat asthma, an inflammatory disease in the airways. The inflammation makes the bronchia sensitive to some factors in the environment, which causes bronchoconstriction. When this constriction occurs, the airways get narrow and it causes symptoms like wheezing, chest tightness, shortness of breath, and coughing. The muscles in the airways tighten, and cells in the airway start to produce more mucus than usual, which narrows the airways even more. The symptoms often start in childhood, but it can start at any age
.
Chronic obstructive pulmonary disease
Both short- and long-acting β2-agonists are used to treat chronic obstructive pulmonary disease. COPD causes airflow limitations in the lungs because of inflammation. Smoking is the main risk factor but inhalation of toxic and harmful particles and gases can also cause the disease. The symptoms are abnormal mucus production, inflation in the lungs that causes airflow limitation, abnormal gas exchange and pulmonary hypertension. COPD is most common in people over fifty who have a long history of smoking. The symptoms are at first mild but worsen over time.
Use
There are two types of β2-agonists, long- and short-acting. They are both inhaled and given by aerosol delivery devices.
Long-lasting β2-agonists are often given in a combination with corticosteroids to treat asthma. Short-acting β2-agonists are used to treat exercise-induced asthma,
and for asthma patients to get a quick relief of symptoms. They are taken 10–15 minutes before exercise. The bronchodilation begins few minutes after inhalation of short-acting β2-agonists and lasts from 4 to 8 hours.
Long-lasting β2-agonists are discouraged in treating acute exercise-induced asthma, because their chronic use might mask poorly controlled asthma.
Mechanism of action
Pharmacokinetic
The kinetics of airway smooth muscle relaxation, as long as the onset and duration of bronchodilation in asthmatic patients, are reflected by the difference in the mechanism of interaction of short- (SABAs) and longacting β2-agonists (LABAs) and the β2-receptor.
There are many formulations of selective β2-agonists; inhalation is the route of choice because it is the most rapidly effective and is associated with minimum side effects.
Sulfate conjugates are the main metabolites; protein binding is rather weak and only insignificant interactions have been found with other drugs.
The main enzymes that regulate metabolism of the catecholamines are COMT and MAO. The commercial SABAs, salbutamol and terbutaline are resistant to COMT but are slowly metabolised by MAO, while the LABAs are resistant to both COMT and MAO. Also, the long duration of action for salmeterol is related to increased lipophilicity of the molecules, allowing it to remain for a longer time in the lungs. β2-agonists are mainly eliminated by the renal process after parenteral administration, while after oral administration a more pronounced metabolic clearance (high first pass effect) is responsible for a low bioavailability. The elimination after inhalation has not been studied but the profile is likely somewhere between what we see after parenteral and oral administration.
Binding to β adrenergic receptors
β-receptors are membrane-bound receptors coupled to G-proteins. Three types of β-receptors have been identified by molecular pharmacology. β1 receptors make up to 75% of all beta receptors and are predominantly located in the heart. β2 receptors are found in vascular and bronchial smooth muscle. β3 receptors, which are presumed to be involved in fatty acid metabolism, are located in the adipocytes.
G-protein coupled receptors consist of single polypeptide chains of 300-600 amino acids and span the plasma membrane seven times. There are three extracellular loops, one of them being the amino-terminus, and three intracellular loops with a carboxy-terminus. The hydrophilic pocket is formed within the membrane by the seven alpha-helical transmembrane domains. The ligand binds to the hydrophilic pocket in the receptor protein and activates the receptor, giving rise to the cellular effect.
When the β2-agonist binds and activates the β2-adrenoreceptor intracellular signaling becomes largely affected through cyclic adenosine monophosphate (cAMP) and protein kinase A (PKA). The coupling of the β2-receptor to adenylate cyclase is affected through a trimeric Gs protein, as shown in figure 2, consisting of an α-subunit (which stimulates adenylate cyclase) and βγ-subunits (which transduce other signals). Adenylate cyclase catalyzes the conversion of adenosine triphosphate into cAMP, which is a second messenger, thereby increasing the intracellular cAMP levels, resulting in relaxation of smooth muscles. cAMP levels are regulated through the activity of phosphodiesterase isozymes/isoforms, which degrades it to 5′-AMP.
The mechanism by which cAMP induces relaxation in airway smooth muscle cells is not fully understood. It is believed that cAMP catalyzes the activation of PKA, which in turn phosphorylates key regulatory proteins involved in the control of muscle tone. cAMP also has a role in inhibition of calcium ion (Ca2+) release from intracellular stores, sequestration of intracellular Ca2+, and reduction of membrane Ca2+ entry, leading to relaxation of the airway smooth muscle.
The binding of norephinephrine to the binding site consists of one ionic bond, three hydrogen bonds and van der Waals interaction in two places. Ionic bonding forms between the protonated amine and Asp-113 in helix 3. Hydrogen bonds are formed from the hydroxyl groups, linked to the catechol ring, to Ser-204 and Ser-207 in helix 5. This binding limits configurational and rotational freedom. Van der Waals forces between aromatic catechol ring and Phe-290 in helix 6 residue and Val-114 in helix 3 residue reinforce the binding. It is believed that the N-alkyl substituents fit into a hydrophobic pocket formed between residues in helix 6 and 7. The beta-carbon is chiral and must have the R-configuration so that the beta-hydroxyl group is oriented towards the Asn-293 residue in helix 6 to form a hydrogen bond essential to binding to the beta-2 receptor.
Mechanism of long acting β2-agonists
Two theories explain the long time of action for LABAs. The first explained the long action in terms of a putative “exosite” or “exoceptor” distinct from the β2-adrenoreceptor that long aliphatic tail of salmeterol binds to with high affinity. This allows the active saligenin head to angle on and off the receptor to activate it repeatedly. Formoterol does not have a long side chain like salmeterol to bind to the “exosite”, so this theory has been questioned. In 1994 Anderson. et al. introduced the plasmalemma diffusion microkinetic theory, explaining what happens to the β2- agonist in the cell membrane lipid bilayer and in the aqueous biophase closest to the binding site of the β2-adrenoceptor. It is postulated that the plasmalemma lipid bilayer of airway smooth muscles acts as a depot for β2-adrenoceptor agonists. β2-adrenoceptor agonists remain available to interact with the β2-adrenoceptor active site after having partitioned into the lipid bilayer.
Structure–activity relationships (SAR)
Basic structure of agonists
The fundamental pharmacophore for all adrenergic agonists is a substituted phenethylamine which increases the duration of action.
Activity of β2-adrenoceptor agonists
Adrenergic agonists that are selective for the β2 subtype cause bronchial dilation and might be expected to relieve the bronchospasm of an asthmatic attack. Nonselective β-agonists have stimulatory cardiac effects and therefore have limited use in cardiac patients with asthma.
Administration of higher doses of short-acting β2-agonists increases duration of action but also increases side effects such as cardiac effects. One approach to avoid these side effects is to use structurally different features that may minimize absorption into systemic circulation. For example, one could use drugs that transform into inactive metabolites upon entry into systemic circulation.
Substituents on the pharmacophore influence whether an analog will be direct- or indirect-acting or a mixture of both. It also influences the specificity for the β-receptor subtypes. Direct-acting analog binds the β-adrenergic receptors directly and generates sympathetic response. Indirect-acting analog causes agonistic effect but without a direct binding to the β-adrenergic receptor, for example, by promoting release of norepinephrine (NE) from the presynaptic terminal or by inhibiting reuptake of released NE.
Basic structure for every β2-agonists
Figure 4 shows the phenyl rings that are used for β2-agonists. They are named resorcinol ring, a salicyl alcohol or an m-formamide group. Figure 5 shows where different substituents on phenylethylamine take places marked as different R-groups.
Activity of R-groups listed
The difference between substituents R1-R5 is described below. All marketed β2-agonists have hydroxyl group in position R3 and most often in position R5.
RN: This group determines α- or β-receptor selectivity. The larger the substituent, the greater the selectivity for the β-receptor. If t-butyl is positioned at RN it shows high affinity for the β2-receptor. A long phenylbutoxyhexyl substituent in this position gives high β2-selectivity and also high lipophilicity and therefore a longer duration of action.
Rα: Substituents other than hydrogen would give increased duration of action. An ethyl group would increase the selectivity for the β2-receptor. However, an ethyl group seems to cause increased adverse effects and low β2-receptor potency compared to other β2-selective agonists.
Rβ: A hydroxyl group gives direct action to the β-receptor. As noted earlier, all marketed β2-agonists have a hydroxyl group in this position which makes the compound chiral, and is active when it has the (R)-configuration.
R5 or R3: Hydroxyl group placed on carbon number 5 or 3 (meta position) gives direct action to the β-adrenergic receptor.
R4: Either hydroxyl group or hydrogen group in this position gives direct action to the β-receptor.
Summarizing a few β2-adrenoceptor agonists and their structure activity shows how they act differently referred to potency, selectivity, affinity and duration of action (see table 1):
Synthesis of β2-adrenoceptor agonists
The β2-agonsist that are clinically used are all substituted β-phenethylamine (see figure 5) and they have three kinds of phenyl rings shown in figure 4. They are called resorcinol ring, salicyl alcohol ring or N-formamide ring. The alcohol substituents in the phenyl ring are reactive and complicate the synthesis of the β2-agonists. A protection step is needed while the N-residue is added in position R1 (figure 5). Another thing that complicates the synthesis is obtaining optically pure R (-) enantiomer of the compound. The stereochemistry is very important for activity because only the R (-) enantiomer is able to form the hydrogen bonds necessary to fit in the binding site and activate the β2-receptor.
Salbutamol is usually inhaled in racemic mixtures (for example Ventolin). By treating asthma with optically pure (R)-salbutamol the risk of side effects, such as nervous system stimulatory effects and cardiac arrhythmia, can be minimized. There are several routes for enantioselective synthesis, as well as methods for synthesis of the racemic mixture followed by chiral resolution.
Stereoselective synthesis of tributalin and salbutamol acetal can be done from O-protected-(R)-cyanohydrins. F. Effenberg, et al. describe a way for the synthesis. The main complications are to perform the deprotection step without racemization and to form a pure salt. A Ritter reaction can be used for an N-tertiary butylation. In this experiment deacetylation of (R)-salbutamol acetal was unsuccessful so it can not be used to obtain pure (R)-salbutamol. Figure 6 shows the main steps in the synthesis of salmeterol and tributalin.
See also
Beta2-adrenergic agonist
Alpha-adrenergic agonist
Asthma
Beta blocker
Beta-1 adrenergic receptor
Beta-2 adrenergic receptor
Beta-3 adrenergic receptor
COPD
Inhalation therapy
GPCR
Catecholamine
References
Beta2-adrenergic agonists
beta2 agonists | Discovery and development of beta2 agonists | [
"Chemistry",
"Biology"
] | 3,611 | [
"Life sciences industry",
"Medicinal chemistry",
"Drug discovery"
] |
44,298,481 | https://en.wikipedia.org/wiki/Bucket%20chain%20excavator | A bucket chain excavator (BCE) is a piece of heavy equipment used in surface mining and dredging. BCEs use buckets on a revolving chain to remove large quantities of material. They are similar to bucket-wheel excavators and trenchers. Bucket chain excavators remove material from below their plane of movement, which is useful if the pit floor is unstable or underwater.
History
The first documented use of a bucket chain excavator was in 1859 by Alphonse Couvreux, a French entrepreneur. Several Couvreux BCEs were used in the construction of the Suez Canal.
Overview
A bucket chain excavator works similarly to a bucket wheel excavator, using a series of buckets to dig into the material before dumping it in the bucket chute and depositing it through a discharge boom. The primary difference is that the buckets are mounted on a flexible chain similarly to a chainsaw blade rather than on a rigid wheel. BCEs are used primarily to excavate material below the vehicle's superstructure while bucket wheel excavators focus primarily on excavating top soil overburden and/or resources.
BCEs vary in range and size, although the majority of them are extremely large, with some capable of excavating 14,500 m3/h. The average BCE from Tenova Takraf for example, weighs around 1,150 tons and has a combined length of 58.5 meters, with a 23.5 meter long bucket ladder. The speed of the bucket chain is 1.22 m/s with a digging force of 1,170 kN/m2. BCEs such as the RK 5000 from the Czech Republic weigh up to 5,000 tons. The largest BCE model currently known is the Takraf Type Es 3750, with a length of over 130 meters, a height of around 40 meters and a weight of
Nevertheless, bucket chain excavators are usually smaller than bucket wheel excavators, dragline excavators or conveyor bridges due to the limitations of excavating materials below the base of the vehicle.
Structure
The superstructure of a bucket chain excavator is similar to that of a bucket wheel excavator.
The primary component of bucket chain excavators is the bucket ladder and the bucket-chain. Unlike the buckets on a BWE, the buckets on the chain face downwards, allowing the machine to remove overburden or materials significantly below the bench or travel level.
The excavated materials are deposited through the bucket chute. Material can be transferred to a bench conveyor directly or via a discharge boom or mobile conveyor bridge.
Like the BWEs, bucket chain excavators also feature a fixed or rotating superstructure with a counterweight boom that allows the cutting boom a certain degree of verticality. Likewise have a substructure equipped with either a rail or crawler-mounted undercarriage for mobility and transportation. Some BCEs have 'hopping' pontoons similar to those found on walking dragline excavators.
Gallery
See also
Long reach excavator
References
Engineering vehicles
Excavators
Dredgers
Mining equipment
Articles containing video clips | Bucket chain excavator | [
"Engineering"
] | 653 | [
"Engineering vehicles",
"Mining equipment"
] |
44,299,071 | https://en.wikipedia.org/wiki/Beta%20bulge%20loop | Beta bulge loops are commonly occurring motifs in proteins and polypeptides consisting of five to six amino acids. There are two types: type 1, which is a pentapeptide; and type 2, with six amino acids. They are regarded as a type of beta bulge, and have the alternative name of type G1 beta bulge. Compared to other beta bulges, beta bulge loops give rise to chain reversal such that they often occur at the loop ends of beta hairpins; hairpins of this sort can be described as 3:5 (for a type 1 β bulge loop) or 4:6 (for type 2). Two websites are available for finding and examining β bulge loops in proteins, Motivated Proteins: and PDBeMotif: .
Type I beta bulge loops have two characteristic inter-main-chain hydrogen bonds. One is between the CO of residue i and the NH of residue i+3 (a β-turn); the other is between the CO of residue i+4 and the NH of residue i.
Type 2 beta bulge loops have two characteristic inter-main-chain hydrogen bonds. One is between the CO of residue i and the NH of residue i+4 (an α-turn); the other is between the CO of residue i+5 and the NH of residue i.
Beta bulge loops often have an aspartate, asparagine, serine or threonine at residue i, together with a nest (protein structural motif) at residues i+2 to i+4 (type 1) or residues i+3 to i+5 (type 2), with the side chain oxygen binding to the main chain NH groups of the nest. Site-directed mutagenesis of asx residues within a protein's β bulge loops has been described, showing that the side chain of an asx residue at various alternative positions within a β bulge loop binds to the nest and thereby helps stabilize the loop.
References
Protein structural motifs | Beta bulge loop | [
"Biology"
] | 405 | [
"Protein structural motifs",
"Protein classification"
] |
44,299,208 | https://en.wikipedia.org/wiki/ST%20staple | The ST staple is a common four- or five-amino acid residue motif in proteins and polypeptides with serine or threonine as the C-terminal residue. It is characterized by a single hydrogen bond between the hydroxyl group of the serine or threonine (at residue i + 3 or i + 4) and the main chain carbonyl group of residue i. Motifs are of two types, depending whether the motif has 4 or 5 residues. Most ST staples occur in conjunction with an alpha helix, and are usually associated with a slight bend in the helix. Two websites are available for finding and examining ST staples in proteins: Motivated Proteins and PDBeMotif.
References
Protein structural motifs
Pentapeptides | ST staple | [
"Biology"
] | 153 | [
"Protein structural motifs",
"Protein classification"
] |
44,300,180 | https://en.wikipedia.org/wiki/Limacella%20guttata | Limacella guttata is a mushroom-forming fungus in the family Amanitaceae. Limacella guttata is found in Europe and North America, where it grows in damp woodlands typically dominated by deciduous plants such as ash, beech, and elm. The specific epithet guttata is derived from Latin, meaning "with droplets".
References
External links
Amanitaceae
Fungi described in 1793
Fungi of Europe
Fungi of North America
Fungus species | Limacella guttata | [
"Biology"
] | 93 | [
"Fungi",
"Fungus species"
] |
44,301,018 | https://en.wikipedia.org/wiki/Oroide | Oroide is copper and zinc, or copper and tin, often employed inexpensively for decorative purposes where a gold-colored metal is desirable.
Oroide may refer to:
Brass, an alloy of copper and zinc that has a bright gold-like appearance
Bronze, an alloy of copper and (in modern times) tin
Other gold-colored copper alloys
See also
Iron pyrite, a non-oroide mineral sometimes referred to as "fool's gold"
Copper alloys | Oroide | [
"Chemistry"
] | 96 | [
"Alloys",
"Copper alloys"
] |
44,301,349 | https://en.wikipedia.org/wiki/Point%20of%20care%20medical%20information%20summary | Point of care medical information summaries are defined as "web-based medical compendia specifically designed to deliver predigested, rapidly accessible, comprehensive, periodically updated, and evidence-based information" to healthcare providers.
Products
BMJ Best Practice
DynaMed
UpToDate
See also
Clinical decision support system
References
Evidence-based medicine
Medical databases
Medical websites
Online databases
Health informatics | Point of care medical information summary | [
"Biology"
] | 80 | [
"Health informatics",
"Medical technology"
] |
44,301,737 | https://en.wikipedia.org/wiki/Rote%20Liste | The , full name , is a red list of threatened breeds of domestic animal published annually by the Gesellschaft zur Erhaltung alter und gefährdeter Haustierrassen, the German national association for the conservation of historic and endangered domestic animal breeds.
History
The GEH was founded in Witzenhausen, in Hesse, central Germany, in 1981. In 1987 it established the criteria on which the Rote Liste is based. The list is published annually, and attributes one of four categories of conservation risk to domestic breeds of cattle, dogs, goats, horses, pigs, rabbits and sheep, of chickens, ducks, geese and turkeys, and of bees; listing of domestic pigeon breeds is in preparation. Some breeds from outside Germany are listed separately. The four levels of risk are:
I: , extremely endangered
II: , seriously endangered
III: , endangered
, alert
The risk level is calculated using a formula that takes into account five criteria: the number of breeding animals or breeding females; the percentage of pure-bred matings; the five-year trend in breed numbers; the number of breeders or herds; and the interval between generations of the animal.
The GEH also publishes, in conjunction with the , the German national association of poultry breeders, a separate list of the historic poultry breeds and colour varieties that were raised in Germany before 1930. The same levels of conservation risk are assigned as in the main red list.
Endangered breeds
In 2014 the breeds listed were:
Note
See also
Rare breed (agriculture)
IUCN Red List
References
Agriculture in Germany
Biodiversity
Lists of animals by conservation status
Sustainable agriculture
Rare breed conservation | Rote Liste | [
"Biology"
] | 325 | [
"Biodiversity"
] |
44,301,990 | https://en.wikipedia.org/wiki/MicroSolutions%20Backpack | MicroSolutions Backpack was a line of peripheral devices introduced in 1990 allowing users to attach a peripheral drive, namely hard drives, CD-ROM drives, and DVD±RW drives, to their system. When the original model was released, USB ports did not yet exist, so the drive plugged into a system's printer port. Backpacks could be daisy-chained and still allow for printer usage. Some models also offered audio capability via expansion. Later models introduced faster connectivity to the host system by means of a proprietary PC Card, and later USB. MicroSolutions was located in DeKalb, Illinois, USA.
References
Computer peripherals | MicroSolutions Backpack | [
"Technology"
] | 134 | [
"Computer peripherals",
"Components"
] |
44,302,332 | https://en.wikipedia.org/wiki/Cladornis | Cladornis is an extinct genus of bird from the early Oligocene of Argentina. Known from a single partial tarsometatarsus, its taxonomic placement is uncertain. It has been variously described as some kind of terrestrial penguin, a pelecaniform, and a "very large and extremely weird land bird". The shaft the tarsometatarsus of Cladornis was very flat and short, and the distal head suggests strong development of the toes.
References
Prehistoric bird genera
Oligocene birds
Neognathae
Species known from a single specimen | Cladornis | [
"Biology"
] | 114 | [
"Individual organisms",
"Species known from a single specimen"
] |
44,302,809 | https://en.wikipedia.org/wiki/Ecopop | Ecopop (ECOlogie et POPulation, "Ecology and Population") is a Swiss voluntary association established in 1971 dedicated to the preservation of non-renewable resources and the reduction of overpopulation.
Ecopop is a member of European Population Alliance (founded 2012).
Founded under the mathematical trend of exponential growth of world population and the finiteness of natural resources, and inspired by the Club of Rome, the association is formed as part of the nascent ecology movement as Arbeitsgruppe Bevölkerungsentwicklung ("working group for population development"). It was renamed to its current name in 1987.
It was active throughout the 1970s to 2000s in organising conferences and podiums on population growth.
Popular initiative
In 2011, the general assembly decided to launch a popular initiative
with the aim of reducing population growth in Switzerland.
The initiative was officially declared valid on 4 December 2012. It was submitted to the voters on 30 November 2014, who rejected it (74.1% NO votes).
The initiative proposes to insert two articles into the Swiss Federal Constitution:
reduction of net population growth due to immigration to a maximum of 0.2% of total population per year
at least 10% of Swiss federal development aid is to be invested in programs to encourage voluntary family planning.
Throughout the 40 years of its existence the association had ostensibly been part of the ecology movement, proposing degrowth out of Malthusian concerns mostly aimed at an academic or intellectual public, and during the 1970s it explicitly denounced populist or xenophobic motivation for immigration control advocated by James Schwarzenbach.
Nevertheless, in the political climate of the immigration debate in Switzerland, especially due to the proximity of Ecopop's initiative to the immigration referendum of February 2014, which resulted in widespread fears among the political and economic elite of deteriorating relations with the European Union, critics tended to accuse Ecopop or its supporters of (variously) xenophobic, racist, fascist, selfish or hypocritical motives.
These attacks were mostly based on the initiative's second paragraph dedicated to global rather than national population growth, as the idea of foreign aid invested in curbing population growth in developing countries was attacked as politically incorrect and some leftist critics went as far as equating it with child euthanasia in Nazi Germany.
Recommendations by parties and organisations were predominantly negative,
even Green Party of Switzerland, the Green Liberal Party of Switzerland and Greenpeace Switzerland took a negative stance, as did the notoriously immigration-critical Swiss People's Party (on the national level, with several cantonal sections in support).
While leftist opposition to Ecopop is mostly expressed as criticism of xenophobia, centrist and right-of-center parties oppose it because of its economic repercussions, as a cap on immigrant workers in Switzerland would deprive the economy of flexible recruitment of specialists as well as deteriorate Switzerland–European Union relations.
See also
Environmental movement in Switzerland
Immigration to Switzerland
List of organisations campaigning for population stabilisation
List of population concern organizations
Malthusianism
References
Environmental organisations based in Switzerland
Population concern organizations
Degrowth
Anti-immigration politics in Europe
Politics of Switzerland
Environmental organizations established in 1971
1971 establishments in Switzerland | Ecopop | [
"Environmental_science"
] | 645 | [
"Degrowth",
"Environmental ethics"
] |
44,302,854 | https://en.wikipedia.org/wiki/Chytriomyces | Chytriomyces is the type genus of fungi in the family Chytriomycetaceae. The genus was described by mycologist John Sidney Karling in 1945. The family, created by Peter Letcher in 2011, contains species with a Group I-type zoospore, distinguishing it from Chytridiaceae members, which have a Group II-type zoospore.
Taxonomy
J. S. Karling circumscribed Chytriomyces in 1945 for the species C. hyalinus and C. aureus. The genus was intended to include monocentric chytrids with operculate, apophysate, epibiotic zoosporangia that exhibited vesicular zoospore discharge. Another requirement was resting spores that function as prosporangia during germination. With time and the addition of species, the generic concept was altered to include species lacking one or more of these features. Karling was not clear as to which of his species was the type; C. hyalinus was later designated the type. With the use of molecular phylogenetics, it has been determined that several species in this genus did not belong. For example, it was shown that C. poculatus and C. angularis were better classified in the new genus Lobulomyces.
Species
C. appendiculatus
C. aureus
C. closterii
C. confervae
C. cosmaridis
C. elegans
C. fructicosus
C. gilgaiensis
C. heliozoicola
C. hyalinus
C. laevis
C. lucidus
C. macro-operculatus
C. mammillifer
C. mortierellae
C. multioperculatus
C. nagatoroensis
C. parasiticus
C. reticulatus
C. reticulosporus
C. rhizidiomycetis
C. rotoruaensis
C. stellatus
C. suburceolatus
C. tabellariae
C. vallesiacus
C. verrucosus
C. willoughbyi
References
External links
Chytridiomycota genera | Chytriomyces | [
"Biology"
] | 453 | [
"Fungus stubs",
"Fungi"
] |
44,302,873 | https://en.wikipedia.org/wiki/Chytriomycetaceae | The Chytriomycetaceae are a family of fungi in the order Chytridiales.
Genera
Chytriomyces
Rhizoclosmatium
Rhizidium
Podochytrium
Obelidium
Siphonaria
Entophlyctis
Physocladia
Asterophlyctis
Fayochytriomyces
Avachytrium
Odontochytrium
Rodmanochytrium
References
Fungus families
Chytridiomycota | Chytriomycetaceae | [
"Biology"
] | 98 | [
"Fungus stubs",
"Fungi"
] |
44,303,149 | https://en.wikipedia.org/wiki/Nowakowskiella | Nowakowskiella is the sole genus of fungi in the family Nowakowskiellaceae. The genus was circumscribed by German mycologist Joseph Schröter in 1897, while the family was originally circumscribed by Frederick Kroeber Sparrow in 1942, and then published validly in 2009.
The genus name of Nowakowskiella is in honour of Leon Nowakowski (1847-1918), who was a Polish naturalist and botanist (Algology and Mycology) from Warsau.
The genus was published in Nat. Pflanzenfam. (Engler & Prantl) vol.1 (Issue1) on pages 77, 82 and 134 in 1897.
Species
As accepted by GBIF;
Nowakowskiella atkinsii
Nowakowskiella crassa
Nowakowskiella crenulata
Nowakowskiella delica
Nowakowskiella elegans
Nowakowskiella endogena
Nowakowskiella hemisphaerospora
Nowakowskiella keratinophila
Nowakowskiella macrospora
Nowakowskiella methistemichroma
Nowakowskiella moubasherana
Nowakowskiella multispora
Nowakowskiella pitcairnensis
Nowakowskiella profusa
Nowakowskiella ramosa
Nowakowskiella sculptura
References
External links
Chytridiomycota genera
Taxa named by Joseph Schröter
Taxa described in 1893 | Nowakowskiella | [
"Biology"
] | 300 | [
"Fungus stubs",
"Fungi"
] |
44,305,631 | https://en.wikipedia.org/wiki/Aerosol%20mass%20spectrometry | Aerosol mass spectrometry is the application of mass spectrometry to the analysis of the composition of aerosol particles. Aerosol particles are defined as solid and liquid particles suspended in a gas (air), with size range of 3 nm to 100 μm in diameter and are produced from natural and anthropogenic sources, through a variety of different processes that include wind-blown suspension and combustion of fossil fuels and biomass. Analysis of these particles is important owing to their major impacts on global climate change, visibility, regional air pollution and human health. Aerosols are very complex in structure, can contain thousands of different chemical compounds within a single particle, and need to be analysed for both size and chemical composition, in real-time or off-line applications.
Off-line mass spectrometry is performed on collected particles, while on-line mass spectrometry is performed on particles introduced in real time.
History
In literature from ancient Rome there are complaints of foul air, while in 1273 the inhabitants of London were discussing the prohibition of coal burning to improve air quality. However, the measurement and analysis of aerosols only became established in the second half of the 19th century.
In 1847 Henri Becquerel presented the first concept of particles in the air in his condensation nuclei experiment and his ideas were confirmed in later experiments by Coulier in 1875. These ideas were expanded on between 1880 and 1890 by meteorologist John Aitken who demonstrated the fundamental role of dust particles in the formation of clouds and fogs. Aitken's method for aerosol analysis consisted of counting and sizing particles mounted on a slide, using a microscope. The composition of the particles was determined by their refractive index.
In the 1920s aerosol measurements, using Aitken's simple microscopic method, became more common place because the negative health effects of industrial aerosols and dust were starting to be recognized by health organizations. Technological and instrumentation advancements, including improved filters, led to improvement in the aerosol measurement methods in the 1960s. The introduction of polycarbonate filters, called nucleopore filters, enhanced the collection, storage, and transportation of samples without disturbing the physical and chemical state of the particles.
On-line aerosol measurements methods took a little longer than off-line to be developed and perfected. It wasn't till 1973 with W.D. Davis who developed and patented of the real-time single particle mass spectrometry (RTSPMS) instrument. The setup is quite similar to today's AMS system, with the sample being introduced through a small steel capillary into the ion source region. The sample would ionize after striking a hot rhenium filament. The resulting ions were separated in a magnetic sector and detected by an electron multiplier. The method could only ionize elements with ionization potentials below the work function of the filament (~8 eV), typically alkali and alkaline earth metal. The instrument did yield unit resolution up to a mass-to-charge ratio of 115. The RTSPMS instrument had a particle transmission/detection efficiency of 0.2-0.3%. Davis used the RTSPMS instrument to study samples from calibration aerosols, ambient laboratory air, and aerosols sources. Majority of his studies where focused on inorganic salts created in lab. In Davis's analysis of ambient air, he found a significant increase in lead at the end of the day, which was concluded to be due to automobile emissions. This development was the first step towards, today's modern on-line instruments.
The next major development in technological improvement that came out of the 1970s was in 1976 by Stoffel with the development of a magnetic sector RTSPMS technique that had a direct-inlet mass spectrometry (DIMS) also known as particle-inlet mass spectrometry (PIMS). The PIMS instrument was the first to have a deferentially-pumped direct inlet that consists of a stainless steel capillary, followed by a skimmer and conical collimator that focuses the sample into a particle beam that goes on to the ionization region. This type of inlet system is what modern on-line aerosol mass spectrometer instruments use today. In 1982 Sinha and Fredlander developed the particle analysis by mass spectrometry (PAMS), this method was the first to incorporate the optical detection of particles followed by laser desorption/ionization (LDI) in a RTSPMS technique. Prior to this point all RTSPMS methods used surface desorption/ionization (SDI) which consist of a heated metal that ionized the samples. The LDI method involves the sample being hit with a continuous wave, where the particle absorbs photons, and undergoes both desorption and ionization by the same pulse. LDI has several advantages over SDI for on-line single particle mass spectrometry, as such since its development it has been the primary ionization method for RTSPMS.
The last major step in RTSPMS development was in 1994 by Kimberly A. Prather. Prather developed the aerosol time-of-flight mass spectrometry (ATOFMS), this method was the first that allow for simultaneous measurement of size and composition of single airborne particle. This techniques was different then previous methods in that instead of using the unreliable method of using light scattering signal intensity to measure particle size, this method uses a two laser system that allows for aerodynamic sizing.
Off-line
Off-line is an older method than on-line and involves the chemical analysis of sampled aerosols collected traditionally on filters or with cascade impactors (shown to the right) in the field and analyzed back in the lab. Cascade impactors collects particles as they transverse a series of impaction plates, and separate them based on size. The aerosol samples are analyzed by the coupling of pre-separation methods with mass spectrometry. The benefit of this method relative to on-line sampling is greater molecular and structural speciation. The greater molecular and structural speciation is due to the pre-separation. There are many different types of instrumentation used for the analysis due to various type and combinations of the ionization, separation, and mass detection methods. Not one combination is best for all samples, and as such depending on the need for analysis, different instrumentation is used.
The most commonly used ionization method for off-line instrument is electron ionization (EI) which is a hard ionization technique that utilized 70 eV to ionize the sample, which causes significant fragmentation that can be used in a library search to identify the compounds. The separation method that EI is usually coupled with is gas chromatography (GC), where in GC the particles are separated by their boiling points and polarity, followed by solvent extraction of the samples collected on the filters. An alternative to solvent-based extraction for particulates on filters is the use of thermal extraction (TE)-GC/MS, which utilizes oven interfaced with the GC inlet to vaporize the analyte of the sample and into the GC inlet. This technique is more often used then solvent-based extraction, because of its better sensitivity, eliminates need for solvents, and can be fully automated. To increase the separation of the particles the GC can be coupled with a time of flight (TOF)-MS, which is a mass separation method that separates ions based on their size. Another method that utilizes EI is isotope ratio mass spectrometry (IR-MS) this instrumentation incorporates a magnetic sector analyzer and a faraday-collector detector array and separates ions based on their isotopic abundance. Isotopic abundance of carbon, hydrogen, nitrogen, and oxygen isotopic abundance become locally enriched or depleted through a variety of atmospheric processes. This information helps in determining the source of the aerosols and the interaction it has had.
EI is a universal ionization method, but it does cause excessive fragmentation, and thus can be substituted with chemical ionization (CI) which is a much softer ionization method, and is often used to determine the molecular ion. One ionization method the utilizes CI is atmospheric-pressure chemical ionization (APCI). In APCI the ionization occurs at atmospheric pressure with ions produced by corona discharges on a solvent spray, and it is often coupled with high-performance liquid chromatography (HPLC) which provides quality determination of polar and ionic compounds in the collected atmospheric aerosols. The use of APCI allows for the sampling of the filters without the need of solvents for the extraction. The APCI is typically connected to a quadruple mass spectrometer.
Other ionization methods are often used for off-line mass spectrometer inductively coupled plasma (ICP). ICP is commonly used in the elemental analysis of trace metals, and can be used to determine the source of the particles and their health effects.
There are also a range of soft ionisation techniques available for assessing the molecular composition of aerosol particles in greater detail, such as electrospray ionization, which result in less fragmentation of compounds within the aerosol. These techniques are only beneficial when coupled with a high or ultra-high resolution mass spectrometer, such as an FTICR-MS or an Orbitrap, as very high resolution is needed to differentiate between the high number of compounds present.
On-line
On-line mass spectrometry was develop to solve some of the limitations and problem that develop from off-line analysis, such as evaporation and chemical reactions of particles in the filters during long analysis time. On-line Mass spectrometry solves these problems through the collection and analysis of aerosol particles in real time. On-line instruments are very portable and allow for spatial variability to be examined. These portable instruments can be put on many different platforms such as boats, planes, and mobile platforms (e.g. car trailers). An example of this is in the picture at the beginning with the instrumentation attached to an aircraft. Like off-line, on-line mass spectrometry has many different type of instruments, which can be broken up into two types; instruments that measures the chemistry of the particle ensemble (bulk measurement) and those that measure the chemistry of individual particles (single-particle measurement). Thus based on analytical need different instrumentation is used in analysis of the aerosol particles.
Bulk measurement
Generally speaking bulk measurement instruments thermally vaporize the particles prior to ionization, and there are several different ways that the vaporization and ionization is performed. The main instrument that is used for bulk measurements is Aerodyne aerosol mass spectrometer (AMS).
Aerosol mass spectrometer
The Aerodyne AMS provides real-time aerosol mass spectrometry analysis of size-resolved mass concentration of non-refractory components (Ex. organics, sulfate, nitrate, and ammonium). The term non-refractory is assigned to species that evaporate rapidly at 600 °C under vacuum conditions (e.g. organic matter, NH4NO3 and (NH4)2SO4. The schematic of a typical AMS is shown in the figure to the right. The Aerodyne AMS is made up of three sections; The aerosol inlet, the particle sizing chamber, and the particle detection chamber. The aerosol inlet has a flow limiting orifice entrance that is around 100 um in diameter. Once in the chamber the sample goes through aerodynamic focusing lens system, which consist of several orifice lenses that are mount in sequence of decreasing inner diameter. The lens focuses the particles into a narrow particle beam.
The beam now travels through the particle sizing chamber, where the particle aerodynamic diameter is measured. The particle sizing chamber is made up of a flight tube maintained at (~ 10−5 torr). The entrance of the flight tube is a mechanical chopper that's used to modulate the particle beam; then using both the fixed length of the tube and the time-resolved detection of the arrival at the end, the particles' velocities can be determined. Using the velocity, the particle's diameter is obtained. As the particle beam exits the flight tube, it enters the particle composition detection chamber. In this section, the particles collide with a heated tungsten element (~600 °C). At this tungsten element the non-refractory components of the particle beam are flash vaporized and then ionized by EI. Once ionized, the sample can be analyzed with either a quadruple (Q), time-of-flight (ToF), or high-resolution (HR)-ToF mass analyzer.
Single-particle measurements
Generally speaking single-particle measurement instruments desorb particles one at a time using a pulsed laser. The process is called laser desorption/ionization (LDI) and is the primary ionization method used for single-particle measurements. The main advantage of using LDI over thermal desorption, is the ability to analyze both non-refractory and refractory (e.g., mineral dust, soot) components of atmospheric aerosols. Laser vaporization allows precise laser firing when individual particles fly through the vaporization zone, and the systems are thus dubbed single particle mass spectrometers (SPMS). Several versions of SPMS have been reported, including the aerosol time-of-flight mass spectrometer (AToFMS), the laser mass analyzer for particles in the airborne state (LAMPAS), particle analysis by laser mass spectrometer (PALMS), the rapid single-particle mass spectrometer (RSMS), the bioaerosol mass spectrometer (BAMS) b194 Steele et al., 2003), the nanoaerosol mass spectrometer (NAMS), the single-particle laser ablation time-of-flight mass spectrometer (SPLAT), the single-particle aerosol mass spectrometer (SPAMS), and laser ablation aerosol particle time-of-flight mass spectrometer (LAAP-ToF-MS). Among the most commons of these instruments is the aerosol time-of-flight mass spectrometer (AToFMS).
Aerosol time-of-flight mass spectrometer
The AToFMS allows for the determination of mixing state, or distribution of chemical species, within individual particles. These mixing states are important in the determination of climate and health impact of aerosols. The schematic of a typical AToFMS is shown to the right. The overall structure of ATOF instruments is; sampling, sizing, and the mass analyzer region. The inlet system is similar to the AMS by using the same aerodynamic focusing lens, but it has smaller orifices because of its analysis of single particles. In the sizing region particle passes through the first continuous solid state laser that generates an initial pulse of scattered light. Then the particle passes through the second laser that is orthogonal to the first and produces a pulse of scattered light. The light is detected by a photomultiplier (PMT) that is matched up to each laser. Using the transit times between the two detected pulses and the fixed distance the velocity and size of each particle is calculated. Next the particles travel through to the mass analyzer region where it is ionized by a pulsed LDI laser, which is timed to hit the particle as it reaches the center of the ion extraction region. Once ionized, the positive ions are accelerated towards the positive ToF section and the negative ions are accelerated towards the negative ToF section where they are detected.
Applications
Aerosol science and measurements field, especially aerosol mass spectrometry has grown a lot over the last couple decades. Its growth is partly due to the instruments versatility, it has the ability to analyze a particles size and chemical composition, and perform bulk and single-particle measurements. The versatility of aerosol mass spectrometers allow for them to be used for many different applications in both the lab and field. Over the years aerosols mass spectrometers have been used for anything from determining emissions sources, human exposure to pollutants, radiative transfer and cloud microphysics. Most of these studies have utilized the mobility of the AMS and has been fielded in urban, remote, rural, marine, and forested environments around the world. AMS have also been deployed in mobile platforms such as ships, mobile laboratories, and aircraft.
One recent emission study in 2014 was performed by two NASA research aircraft, a DC-8 and a P-3B, that were outfitted with aerosol instrumentation (AMS). The aircraft were sent to perform analysis of atmospheric samples over the oil sands mining and upgrading facilities near Ft. McMurray, Alberta, Canada. The purpose of the study was to test the emission from the facilities, and determine if they match the requirements. The results of the study was that compared to estimates of annual forest fire emissions in Canada, the oil sands facilities are a minor source of aerosol number, aerosol mass, particulate organic matter, and black carbon.
Aerosol mass spectrometry has also found its way into the field of pharmaceutical aerosol analysis, due to its ability to provide real-time measurements of particle size and chemical composition. People who suffer from chronic respiratory disease commonly receive their medication through the use of either pressurized metered dose inhaler (pMDI) or dry powder inhaler (DPI). In both methods the drug is delivered directly into the lungs by inhalation. In recent years, inhaled products have become available which deliver two types of drug within a single dose. Research has shown that the two drugs inhalers provide an enhanced clinical effect beyond that achieved when the two drugs are administered concurrently from two separate inhalers. It was determined using an AToFMS that the respirable particles in a DPI product and pMDI product were composed of co-associated active pharmaceutical ingredients, which is the reason behind the increased effects of the two drug inhalers.
See also
Laser microprobe mass spectrometer
Particulate matter sampler
Aerosol impaction
Particle size analysis
References
Further reading
External links
Centre for Atmospheric Science
TOF-AMS resources
Q-AMS resources
List of publications using all versions of the AMS
Glossary of AMS terms
Mass spectrometry
Aerosols
Aerosol measurement | Aerosol mass spectrometry | [
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"Chemistry"
] | 3,832 | [
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"Instrumental analysis",
"Mass",
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"Aerosols",
"Mass spectrometry",
"Matter"
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44,305,878 | https://en.wikipedia.org/wiki/Directed%20differentiation | Directed differentiation is a bioengineering methodology at the interface of stem cell biology, developmental biology and tissue engineering. It is essentially harnessing the potential of stem cells by constraining their differentiation in vitro toward a specific cell type or tissue of interest. Stem cells are by definition pluripotent, able to differentiate into several cell types such as neurons, cardiomyocytes, hepatocytes, etc. Efficient directed differentiation requires a detailed understanding of the lineage and cell fate decision, often provided by developmental biology.
Conceptual frame
During differentiation, pluripotent cells make a number of developmental decisions to generate first the three germ layers (ectoderm, mesoderm and endoderm) of the embryo and intermediate progenitors, followed by subsequent decisions or check points, giving rise to all the body's mature tissues. The differentiation process can be modeled as sequence of binary decisions based on probabilistic or stochastic models. Developmental biology and embryology provides the basic knowledge of the cell types' differentiation through mutation analysis, lineage tracing, embryo micro-manipulation and gene expression studies. Cell differentiation and tissue organogenesis involve a limited set of developmental signaling pathways. It is thus possible to direct cell fate by controlling cell decisions through extracellular signaling, mimicking developmental signals.
Source material
Directed differentiation is primarily applied to pluripotent stem cells (PSCs) of mammalian origin, in particular mouse and human cells for biomedical research applications. Since the discovery of embryonic stem (ES) cells (1981) and induced pluripotent stem (iPS) cells (2006), source material is potentially unlimited.
Historically, embryonic carcinoma (EC) cells have also been used. Fibroblasts or other differentiated cell types have been used for direct reprogramming strategies.
Methods
Cell differentiation involves a transition from a proliferative mode toward differentiation mode. Directed differentiation consists in mimicking developmental (embryo's development) decisions in vitro using the stem cells as source material. For this purpose, pluripotent stem cells (PSCs) are cultured in controlled conditions involving specific substrate or extracellular matrices promoting cell adhesion and differentiation, and define culture media compositions. A limited number of signaling factors such as growth factors or small molecules, controlling cell differentiation, is applied sequentially or in a combinatorial manner, at varying dosage and exposure time. Proper differentiation of the cell type of interest is verified by analyzing cell type specific markers, gene expression profile, and functional assays.
Early methods
co-culture with stromal cells or feeder cells, and on specific culture substrates:
support cells and matrices provide developmental-like environmental signals.
3D cell aggregate formation, termed embryoid bodies (EBs): the aggregate aim at mimicking early embryonic development and instructing the cell differentiation.
culture in presence of fetal bovine serum, removal of pluripotency factors.
Current methodologies
Directed differentiation
This method consists in exposing the cells to specific signaling pathways modulators and manipulating cell culture conditions (environmental or exogenous) to mimick the natural sequence of developmental decisions to produce a given cell type/tissue. A drawback of this approach is the necessity to have a good understanding of how the
cell type of interest is formed.
Direct reprogramming
This method, also known as transdifferentiation or direct conversion, consists in overexpressing one or several factors, usually transcription factors, introduced in the cells. The starting material can be either pluripotent stem cells (PSCs), or either differentiated cell type such as fibroblasts. The principle was first demonstrated in 1987 with the myogenic factors MyoD.
A drawback of this approach is the introduction of foreign nucleic acid in the cells and the forced expression of transcription factors which effects are not fully understood.
Lineage/cell type-specific selection
This methods consists in selecting the cell type of interest, usually with antibiotic resistance. For this purpose, the source material cells are modified to contain antibiotic resistance cassette under a target cell type specific promoter. Only cells committed to the lineage of interest is surviving the selection.
Applications
Directed differentiation provides a potentially unlimited and manipulable source of cell and tissues.
Some applications are impaired by the immature phenotype of the pluripotent stem cells (PSCs)-derived cell type, which limits the physiological and functional studies possible.
Several application domains emerged:
Model system for basic science
For basic science, notably developmental biology and cell biology, PSC-derived cells allow to study at the molecular and cellular levels fundamental questions in vitro, that would have been otherwise extremely difficult or impossible to study for technical and ethical reasons in vivo such as embryonic development of human. In particular, differentiating cells are amenable for quantitative and qualitative studies.
More complex processes can also be studied in vitro and formation of organoids, including cerebroids, optic cup and kidney have been described.
Drug discovery and toxicology
Cell types differentiated from pluripotent stem cells (PSCs) are being evaluated as preclinical in vitro models of Human diseases. Human cell types in a dish provide an alternative to traditional preclinical assays using animal, human immortalized cells or primary cultures from biopsies, which have their limitations. Clinically relevant cell types i.e. cell type affected in diseases are a major focus of research, this includes hepatocytes, Langerhans islet beta-cells, cardiomyocytes and neurons. Drug screen are performed on miniaturized cell culture in multiwell-plates or on a chip.
Disease modeling
PSCs-derived cells from patients are used in vitro to recreate specific pathologies. The specific cell type affected in the pathology is at the base of the model. For example, motoneurons are used to study spinal muscular atrophy (SMA) and cardiomyocytes are used to study arrhythmia. This can allow for a better understanding of the pathogenesis and the development of new treatments through drug discovery. Immature PSC-derived cell types can be matured in vitro by various strategies, such as in vitro ageing, to model age-related disease in vitro.
Major diseases being modelized with PSCs-derived cells are amyotrophic lateral sclerosis (ALS), Alzheimer's (AD), Parkinson's (PD), fragile X syndrome (FXS), Huntington disease (HD), Down syndrome, Spinal muscular atrophy (SMA), muscular dystrophies, cystic fibrosis, Long QT syndrome, and Type I diabetes.
Regenerative medicine
The potentially unlimited source of cell and tissues may have direct application for tissue engineering, cell replacement and transplantation following acute injuries and reconstructive surgery. These applications are limited to the cell types that can be differentiated efficiently and safely from human PSCs with the proper organogenesis. Decellularized organs are also being used as tissue scaffold for organogenesis. Source material can be normal healthy cells from another donor (heterologous transplantation) or genetically corrected from the same patient (autologous).
Concerns on patient safety have been raised due to the possibility of contaminating undifferentiated cells. The first clinical trial using hESC-derived cells was in 2011. The first clinical trial using hiPSC-derived cells started in 2014 in Japan.
See also
Dedifferentiation
Pluripotency
References
Developmental biology
Induced stem cells
Stem cells
Biotechnology
Cell biology
Biological engineering
Biomedical engineering
Tissue engineering | Directed differentiation | [
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44,306,108 | https://en.wikipedia.org/wiki/Deconica%20horizontalis | Deconica horizontalis is a species of agaric fungus in the family Strophariaceae.
Fungi described in 1788
Strophariaceae
Taxa named by Jean Baptiste François Pierre Bulliard
Fungus species | Deconica horizontalis | [
"Biology"
] | 41 | [
"Fungi",
"Fungus species"
] |
44,306,181 | https://en.wikipedia.org/wiki/Tricia%20%28elephant%29 | Tricia (24 January 1957 – 6 July 2022) was a female Asian elephant which resided at Perth Zoo in Perth, Western Australia. She was born in 1957 in Vietnam and was transported to Perth in 1963. Tricia was named after Tricia Reschke, the Miss Australia from the previous year. Tricia's health began to decline in 2016 and significantly worsened in 2022. She lived to be one of the oldest Asian elephants in the world.
Life at Perth Zoo
Tricia was born in Saigon, Vietnam, on 24 January 1957 and came to Perth Zoo in Perth, Western Australia, in January 1963. She was acquired from Mayfield Kennels, an animal dealer based in Singapore. Tricia was named after Tricia Reschke, who was Miss Australia in 1962, as part of a newspaper competition. She, along with fellow elephant Tania, was officially christened in 1963 by Australian beauty queen Tania Verstak.
For her first two decades at Perth Zoo, Tricia was kept in a small concrete enclosure, but from 1986 lived in a larger enclosure with a swimming pool, mud wallows and a heated barn. Three elephants, a bull named Putra Mas and females Permai and Teduh, joined Tricia at Perth Zoo in 1992; the three females lived together, while Putra Mas was kept separate due to the solitary nature of male elephants. When Teduh died in 2007, Tricia mourned her death for about a year. Usually the most vocal of the Perth Zoo elephants, Tricia remained silent during her depression and grief. Her keepers were relieved when she eventually regained her playfulness. Tricia's enclosure was made three times larger following exhibit upgrades in 2004 and 2005.
Artwork
Tricia and the other elephants at the Perth Zoo made artwork with their trunks, the proceeds of which went to charity. The elephants painted either by holding paintbrushes in their trunks or blowing paint onto canvas with their snouts. In 2016, a Change.org petition was started by an animal rights activist to stop the elephant-created artwork, claiming that the trainers used bullhooks. The Perth Zoo refuted these claims. Tricia's likeness was captured by artist Ross Potter for the Animaze exhibit at the Fremantle Arts Centre.
Decline and death
In July 2022, Perth Zoo disclosed that Tricia's health had been declining over the past few days and she had been experiencing sleep and mobility issues. Her health decline was suspected to have begun in 2016. On the day before her death, Kristy Carey, one of Tricia's caretakers, said, "She knows how to take a piece of your heart and she doesn't return it. There's going to be a huge hole missing when she does go."
Tricia died on the evening of 6 July 2022, surrounded by her caretakers. A statement from Perth Zoo explained, "Tricia's final moments were peaceful. She was surrounded by her carers in her night quarters on Wednesday evening, July 6, 2022." The cause of her death was "age-related complications" and was expected. She died as one of the world's oldest Asian elephants. Female elephant Permai, who had joined Tricia at Perth Zoo in 1992, stayed by Tricia's side in the hours after her death. Tricia did not have any offspring.
Perth Zoo publicly announced her death not long after, which was met with tributes from the public, her caretakers and the Premier of Western Australia, Mark McGowan. McGowan posted to Instagram:
Tricia wasn't just well-known, she was well-loved. Her stature and her grace were compelling. For many, she was a Perth icon. For six decades, she was an integral part of any visit to Perth Zoo. If you lived in Perth at some point in your life then you probably have a memory of Tricia.
Perth Zoo asked the public to not send flowers, but to instead donate to the Tricia Tribute to Conservation Fund, which was named after her.
Tricia was laid to rest in a private ceremony at Perth Zoo in May 2023.
Legacy
, a ferry built in 2019 and operated by Transperth, is named after the elephant. Following her death, Perth Zoo dedicated the Tricia Tribute to Conservation Fund in honour of her. A memorial walk to remember her legacy opened to the public on 10 July 2022.
In 2018, Perth Zoo announced that it would no longer house any elephants after Tricia died, and would move the other two elephants to other zoos.
See also
List of individual elephants
References
1957 animal births
2022 animal deaths
Individual animals in Australia
Visual arts by animals
Individual Asian elephants | Tricia (elephant) | [
"Biology"
] | 962 | [
"Ethology",
"Behavior",
"Animals",
"Visual arts by animals"
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44,306,711 | https://en.wikipedia.org/wiki/Dendrochytridium | Dendrochytridium is a fungal genus in the order Chytridiales. The genus is monotypic, containing the single saprobic species Dendrochytridium crassum, isolated from detritus collected from an Australian tree canopy. Both the genus and species were described as new to science in 2013. Phylogenetically, Dendrochytridium crassum groups together in a clade with other fungi possessing Group II-type zoospores. These fungi, which include representatives from the genera Chytridium, Phlyctochytrium, Chytriomyces, and Polyphlyctis are classified in the family Chytridiaceae.
The generic name combines dendro (derived from Greek, meaning "tree"), which refers to the origin of the first collection, and Chytridium, the type genus of the order Chytridiales. The specific epithet crassum is Latin for "broad", and refers to the broad rhizoids.
References
External links
Chytridiomycota genera
Monotypic fungus genera | Dendrochytridium | [
"Biology"
] | 222 | [
"Fungus stubs",
"Fungi"
] |
68,592,436 | https://en.wikipedia.org/wiki/WR%20128 | WR 128 is a Wolf–Rayet star located about 9,500 light years away in the constellation of Sagitta. A member of the WN class, WR 128's spectrum resembles that of a WN4 star, but hydrogen is clearly present in the star (hence the h in its spectrum), making it the only known hydrogen-rich WN4 star in the galaxy. However, similar H-rich very early WN stars can be found in the LMC and especially in the SMC, but the only other galactic examples of this are WR 3 and WR 152.
Properties
Analysis of WR 128's spectrum with PoWR shows that it has a temperature of around 70,800 K and is losing mass at a very slow pace (in Wolf-Rayet terms), at 10-5.4 M☉/year, or in other words, 1 solar mass every 250,000 years. All this mass is being carried by a very strong stellar wind with a terminal velocity of 2,050 kilometres per second. Taking its distance into account, WR 128 has a luminosity of , or 105.22 L☉, making it one of the dimmest galactic WN stars. Using the Stefan-Boltzmann Law, we can calculate a radius of 2.69 R☉. A "transformed" radius at an optical depth of 2/3, more comparable to other types of stars, is at about 13 R☉.
References
Wolf–Rayet stars
Sagitta
Sagittae, QT
097456
187282 | WR 128 | [
"Astronomy"
] | 320 | [
"Sagitta",
"Constellations"
] |
68,592,789 | https://en.wikipedia.org/wiki/Robert%20Pickersgill%20Howgrave-Graham | Robert Pickersgill Howgrave-Graham (sometimes Howgrave Graham) F.S.A., M.I.E.E. (9 July 1880 – 25 March 1959) was a British polymath. He trained as an electrical engineer and became a teacher, inventor and author but his lasting legacy, through his interest in archaeology, is his work as an antiquarian, historian and photographer. Often noted as a horologist, he became a specialist in medieval church clocks, and his research work on the clocks of both Wells and Salisbury Cathedrals is considered scholarship standard. Upon his retirement from teaching he pursued both his interest in photography and archaeology, becoming Assistant Keeper of the Muniments of Westminster Abbey.
Early life and education
Robert Howgrave-Graham was born in Hampstead, London to Henry Howgrave Graham and Laura Julia (née Tennant). His father Henry was a registrar of patents, becoming first Secretary of the Chartered Institute of Patent Agents, who died just before the end of World War I. Robert's younger brother Hamilton Maurice Howgrave-Graham, C.B.E. (1882-1963) was a civil servant, a long-standing Secretary of the Metropolitan Police, who wrote two books Light and Shade at Scotland Yard and The Metropolitan Police at War about the service.
Both Robert and Hamilton were educated at Felsted School with Robert going on to study electrical engineering at the Finsbury Technical College under Silvanus P. Thompson between 1896 and 1899.
Career
Howgrave-Graham published his first article while still a student and throughout his life he published books and articles on diverse subjects from x-rays to clocks to funeral effigies, and his work is often referenced.
Electrical engineering
Howgrave-Graham commenced his career at the place he studied, City and Guilds of London Technical College, Finsbury, working as a demonstrator. He moved on to teaching and research work, undertaking experimental work with electric oscillations and on wireless technology. He is acknowledged as a contributor to the early development of wireless telegraphy. The Science Museum, London has, in its collection, an experimental Lodge-Muirhead wireless telegraph receiver, designed and built by Howgrave-Graham in about 1905 which he gave to the museum in 1923. The construction of the receiver is described in his book Wireless Telegraphy for Amateurs.
Due to health issues, Howgrave-Graham did not see active service in the First World War but, alongside his continued teaching duties, he lectured artillery brigades on the principles of gunnery and on field telephony. He also undertook research work on naval wireless telegraphy.
Shortly after the war Howgrave-Graham took up the post of lecturer at Northampton Polytechnic, an institute of technology in Clerkenwell, where he worked from 1919 until his retirement in 1945.
Clocks
Beside his teaching career, Howgrave-Graham pursued his outside interests, one of which was the workings of medieval clocks. In the late 1920s he gave a lecture to a meeting of the St Albans and Herts Architectural and Archaeological Society on Richard of Wallingford’s astronomical clock. At that time, he had already submitted a paper to the Society of Antiquaries of London questioning widely held views concerning the earliest appearance of clocks in Europe and in England.
After visiting Salisbury Cathedral and discovering the workings of an ancient clock, the horologist T. R. Robinson contacted Howgrave-Graham, who he had met while attending a lecture at Northampton Polytechnic that he described as “an inspirational speech on ancient turret clocks” to advise him of the find. After inspecting the clock, Howgrave-Graham worked with the friends of Salisbury Cathedral in having the clock brought down from the Great Tower and exhibited in the north transept of the cathedral. Howgrave-Graham continued to undertake research on the Salisbury clock and was instrumental in having the clock restored. He also undertook considerable research on the Wells Cathedral clock and promoted the theory that the Salisbury and Wells clocks were linked and from a contemporaneous period. The Wells Cathedral clock mechanism, which Howgrave-Graham helped to restore, is now exhibited at the Science Museum. His monograph, Peter Lightfoot - Monk of Glastonbury, and the Old Clock at Wells, was published in 1922.
Westminster Abbey
Howgrave-Graham was appointed assistant keeper of the Muniments at Westminster Abbey in 1945 and continued in the post until his death in 1959.
During his time at the Abbey he worked painstakingly on the restoration of a number of wooden funeral effigies that had been severely damaged after an incendiary bomb attack and the subsequent water ingress. His conservation work on the earliest effigy of Edward III and the effigy of Henry VII is particularly noteworthy and revealed that the features were actual death masks. Various publications detail the work he carried out, for example, in the book Henry VII, the author Stanley B. Chrimes tells us how Howgrave-Graham “undertook with remarkable success the most formidable task of restoring the saturated, partly disintegrated effigies…” and in Funeral Effigies of Westminster Abbey it is acknowledged that his work and photographs together with a subsequent study by the Victoria and Albert Museum “revealed a great deal about the construction of the effigy head (of Henry VII)”.
Howgrave-Graham was made an honorary member of the Art Workers' Guild in 1952, having previously given a lecture on ‘Little Known Sculpture of Westminster Abbey’ to the Guild in 1940. He was also made a Fellow of the Society of Antiquaries of London.
Photography
Both the Science Museum and Westminster Abbey extol Howgrave-Graham's prowess as a photographer. The Science Museum describes him as a “skilled photographer using it to record medieval church architecture” whilst the Abbey, whose library contains a large collection of his negatives, calls him “a gifted photographer”.
As J. Greig remarked in the obituary for Nature “photography was, for him (Howgrave-Graham), handmaiden to archaeology. The art of photographing the interesting and beautiful features of the architecture of medieval buildings was one at which he excelled and many of his photographs, some of striking beauty, have been reproduced in books on Gothic art.” An example being a photograph of Bristol Cathedral that appeared in the 1972 book Mediaeval Architect by John Harvey. Howgrave-Graham also took the photographs for the book Unknown Westminster Abbey by L. E. Tanner published in 1948.
As early as 1915 Howgrave-Graham exhibited and gave a lantern lecture at the annual exhibition of The Royal Photographic Society on Canterbury Cathedral.
The British Library has a set of twelve souvenir photographs of the coronation of King George VI on 12 May 1937, taken by Howgrave-Graham and photographs attributed to him are held in the archives of Historic England and also by the Conway Library whose archive of primarily architectural images is being digitised under the wider Courtauld Connects project.
Private life
Howgrave-Graham married late in life after proposing to his housekeeper, Beatrice Purdy, during a World War II air raid. The couple were married in Westminster Abbey on 7 November 1944.
Robert Howgrave-Graham died on 25 March 1959 and his ashes are buried in the Islip Chapel in Westminster Abbey.
Publications
The Wells Clock, Wells : Friends of Wells Cathedral, 1971
‘The Earlier Royal Funeral Effigies, New Light on Portraiture at Westminster Abbey’ in Archaeologia, Vol. 98 1961, pp. 159–169
The Cathedrals of France, London : B. T. Batsford, 1959
‘Salisbury & the West-Country Clocks’ in Antiquarian Horology, Vol.2/1, 1956
‘Automata at Salisbury’ in Antiquarian Horology, Vol.2/5, 1956
‘Royal Portraits in Effigy: Some New Discoveries in Westminster Abbey’ in Journal of the Royal Society of Arts, Vol. 101, No. 4900, 29 May 1953, pp. 465–474
‘Ancient Turret Clocks’ in Antiquarian Horology, Vol.1/3, 1953
‘New light on Ancient Turret Clocks’ in Antiquarian Horology, Vol.1/5, 1953
‘Westminster Abbey: Various Bosses, Capitals, and Corbels of the Thirteenth Century’ in Journal of the British Archaeological Association, Vol. 8, Iss.1, pp. 1–4, 1943
The Dover Castle Clock; How Old is the Dover Castle Clock’ in The Watch and Clock Maker, Vol 4, 1931, pp. 52–53, 180-182
X-Rays Simply Explained: A Handbook on Röntgen Rays in Theory and Practice, London : Percival Marshall & Co, 1928, Third Edition, London : Forgotten Books, 2018,
‘A Great Cathedral Clock Rediscovered’ in Practical Clock and Watchmaker, November 1929, pp. 445–7
‘Some Clocks and Jacks, with Notes on the History of Horology’ in Archaeologia, Vol. 77 1928, pp. 257–312
Peter Lightfoot - Monk of Glastonbury, and the Old Clock at Wells, Glastonbury : Avalon Press, 1922. Reprinted by Creative Media Partners, LLC, 2015,
Wireless Telegraphy for Amateurs, 1907, London : Percival Marshall & Co, 1907
X-Rays Simply Explained - A Handbook on the Theory and Practice of Radiography, originally published in 1904. Reprinted by Krauss Press, 2011,
‘The Synchronising of Alternators’ with M.R. Gardner in Journal of the Institution of Electrical Engineers, Vol. 28, Issue 131, 1989, pp. 658–664
References
1880 births
1959 deaths
People from Hampstead
British electrical engineers
Horology
Medievalists
Fellows of the Society of Antiquaries of London | Robert Pickersgill Howgrave-Graham | [
"Physics"
] | 1,982 | [
"Spacetime",
"Horology",
"Physical quantities",
"Time"
] |
68,593,751 | https://en.wikipedia.org/wiki/QY%20Puppis | QY Puppis is a K-type supergiant star in the constellation of Puppis. With a radius of , it is on the smaller end of the largest known stars. A variable star, its apparent magnitude varies from 6.24 to 6.71, making it very faintly visible to the naked eye under ideal observing conditions, when it is at its brightest.
Properties
In 1981, Armando Arellano Ferro published an article stating that the star, then called HD 63302, might be a variable star. It was given its variable star designation, QY Puppis, in 1985. QY Puppis has been classified in the General Catalogue of Variable Stars as a semiregular variable star of type SRD. QY Puppis has a temperature of 4,251 K, and has expanded to a radius of . It is approximately 60 million years old, with a mass of .
References
Puppis
K-type supergiants
Semiregular variable stars
3026
063302
038031
Durchmusterung objects
Puppis, QY | QY Puppis | [
"Astronomy"
] | 220 | [
"Puppis",
"Constellations"
] |
68,594,945 | https://en.wikipedia.org/wiki/Enigma%20%28DVB%29 | Enigma2, the second generation of Enigma software, is an application used in Linux-based Digital Video Broadcasting (DVB-S, DVB-C, DVB-T) receivers or TV set-top boxes and Internet Protocol television receivers. It creates a graphical user interface to control the said devices using a remote control and provides features such as tuning available satellite transponders, cable channels and terrestrial television transmitters (according to available tuners) or accessing material via Internet Protocol television (IPTV), watching a TV program or listening to radio, time shifting, Digital video recorder, streaming media programs to other devices (personal computer, mobile phone), etc. Other features are available through plugins – for example Electronic program guide (EPG), Hybrid Broadcast Broadband TV (HbbTV), access to TV archives and movie databases, playback of multimedia files, viewing photos, etc.
The name Enigma2 is often used to refer to the whole Linux distribution designed for TV receivers containing the Enigma2 application. Sometimes the distribution is called Linux E2 or E2 Linux, but usually it is named after the specific distro or development team – OpenATV, OpenPLi, OpenViX, EGAMI, OpenEight, Black Hole, OpenDroid, PurE2, etc. The distribution was originally developed for Dreambox receivers, but after 2010 a number of manufacturers of similar equipment appeared, such as Formuler, GigaBlue, Octagon, Opticum, Unibox, Vu+, Zgemma, etc.
The devices
Devices designed for Enigma2 (i.e. satellite receivers, set-top boxes and IPTV receivers, often simply called boxes) are equipped with one or more DVB-S, DVB-C and DVB-T tuner(s) (unless they are pure IPTV receivers), a Remote control receiver and an Ethernet and/or Wi-Fi network adapter. To receive coded/scrambled programs the box may be equipped with one or more slots for decoding cards. The operating system is usually stored on internal flash memory, whereas to record programs or to play multimedia files a larger, internal or external, hard disk, SSD, USB flash disk or memory card can be used. The device may use Network Attached Storage or a disk volume on a personal computer using Samba or NFS protocol as well. The system is designed to be controlled by a Remote control similar to those used for TV receivers. The TV set usually connected via a HDMI (or SCART) cable works as a multimedia monitor. The device may connect to a home audio system either via TOSLINK or Bluetooth.
The box can be accessed with terminal emulation protocol telnet, ssh, or via FTP. The OpenWebif module implements a web server that allows control of the box from a PC using a web browser. The box can act as a streaming server, streaming material received by its tuners or direct from its hard drive or any mounted device available to it.
History
Enigma is one of the Graphical user interfaces developed for digital satellite receivers DBox-2 during the TuxBox project in 2000-2001. The development was then continued by Dream Multimedia for their receivers. In 2006 Dream Multimedia released a new open source version of the software called enigma2. Around that time many receiver manufacturers who were competitors of Dream Multimedia started using the software developed by Dream Multimedia without contributing to system development. Dream Multimedia therefore decided not to continue system development as free software and introduced its own Dreambox OS. Currently, there are about 20 teams that develop the enigma2 application, control and maintain their own versions of the distribution for dozens types of devices.
Features
The main feature is displaying the received TV program on the TV screen connected usually using an HDMI cable transferring sound as well. At the same time Enigma2 creates graphical user interface controlled using an infrared remote commander, that displays on the TV screen in the form of menu, dialogues and forms allowing control of all basic settings of the set-top box or the receiver.
Plugins
Enigma2 features can be extended by various plugins.
Some plugins offers specific features of smart TVs, like
Electronic program guide (EPG)
Display tuned channel and their switching
Digital video recorder and Time shifting
Playback of video and audio recordings
Teletext
Hybrid Broadcast Broadband TV
KODI multimedia centre
Logical channel number list creation (AutoBouquetsMaker, and others)
Some plugins appear in the Plugins menu and can be customised from there while others blend seamlessly into the graphical user interface in such a way that it is not always clear what is a plugin and what is a built in feature. And, depending on the distro, some plugins are built into the base distribution, for example, Graphical EPG and AutoTimer recordings.
Disk
To use an Enigma2 box as a Digital video recorder, or for time shifting or other features like system backup and setup it is possible to connect an external hard disk or USB flash drive. Some receivers contains a builtin disk or have a pull-out drawer to install an internal hard disk drive. Also use of network-attached storage or a shared disk from a computer is possible.
Network interface
For Internet access, access to network disk storages or to shared folders on computer, stream programs to a computer, mobile phone or other receiver and to control the receiver from a computer using web browser, or other purposes most receivers have builtin interface Ethernet and/or Wi-Fi, or it is possible to connect an external WiFi module. The receiver uses DHCP for dynamic assignment of IP address, but when the user wants to control receiver using web browser, file transfer protocols File Transfer Protocol (FTP) or SFTP or to login interactively to the receiver using telnet or SSH, it is better to configure the receiver to use a fixed IP address.
Decryption card interfaces
Enigma 2 boxes are equipped with interfaces for popular conditional access cards like Common Interface slot and/or smart card reader to allow reception of encrypted content which may be stored or streamed after decryption.
Controlling using a web client
Most of the enigma2 features can be controlled by web browser using interface OpenWebif. It contains a virtual remote control offering the same features as remote control supplied with the receiver. Use of this interface must be enabled in receiver settings and an access password must be generated. Connection to the receiver is usually possible only from within the LAN network as most internet providers assign IP addresses dynamically and do not allow connecting from the public internet to home network.
Video streaming
Enigma2 allows streaming of the received programs as well as multimedia files stored on the disk.
The easiest access to streaming is with OpenWebif. By clicking to the screen icon or mobile phone icon next to the desired program or multimedia file, a *.m3u stream is opened that can be reproduced by VLC or any other application that is compatible with the selected source.
Cheaper receivers with single tuner allow streaming, recording and watching programs from only one multiplex or satellite transponder at a time. Many boxes have multiple tuners which allows streaming, watching or recording programs from more than one multiplex or satellite transponder simultaneously. The latest boxes rather that having multiple tuners have a newer type of tuner module known as Full Band Capture which allow up to 8 multiplexes to be tuned simultaneously, per tuner module. When there are not enough tuners for the current demand, recordings take priority, so while recording a program on single-tuner box it is not possible to switch to channels on other multiplexes or transponders and even while watching a program the receiver may automatically switch to another program when a programmed recording starts.
Feeds
Each distro has its own feeds available from the internet via the network adaptor. The feeds contain a wide array of plugins and other addons that can be downloaded and installed at the click of a button. Package management and versioning is handled by opkg.
Software upgrade
Software update is an extension of the feeds. When a new version or build is available an icon is displayed in the graphical user interface to alert the user. It is recommended to make system backup before the upgrade, to allow reinstating the previous working system version in case of any problem. Some distros, such as OpenViX do this automatically. Upgrades to new builds are normally limited to the same version, and to change version a complete reflash is required.
System backup and setup
Enigma2 allows backing up the system to an attached disk or network-attached storage. It is possible to make a backup of settings only (configuration files, their initial list can be modified), or of the whole system (internal volume, or more exactly one partition of it called a slot), on Multiboot systems also a multiboot loader.
Images
Image is complete disk image. As a record of standard film has gigabyte size, the usual software installation method to a set-top box with enigma2 is installation of a complete disk image, which has usually size of around one hundred megabytes.
Multiboot
Some receivers allow installing on the internal volume a number of different system images (usually max. 4, each to separate space called a slot) and determining before a system restart which slot should be used to boot the system. This feature is useful to evaluate different disk images, either different versions or from different teams, and in case of problems with the receiver (allows distinguishing between hardware and software problems). The receiver can also be reflashed to a different operating system or system version using USB disk or SD/SDHC card.
Skins
The look of the enigma2 application in most distributions is widely configurable. Skin in this context means complete description of the look, that is placement of the menu, its contents, colors, fonts, graphics and icons in individual menu levels, as well as information displayed on information screens etc. Some skins are pre-installed in the base image and others can be downloaded from the feeds. Selecting the skin is done from the menu and after a GUI restart the new skin is displayed.
File transfer
Pro File transfer between receiver and computer in home network is possible using protocols FTP, SFTP or shared directory trees in receiver using protocols Samba or Network File System (NFS). Downloading multimedia files from receiver to a computer can be performed using OpenWebif interface as well.
Picons
Picons (PLi icons) are graphical icons with the logo of individual TV/radio stations. They make visual navigation through channel lists easier and faster.
Command line environment
It is possible to connect to the enigma2 box using terminal emulator protocol telnet or SSH. A password must be generated either using the GUI or SSH. After login the user gets to the Linux Command-line interface, and therefore some knowledge this environment and some specialties of E2 Linux systems is necessary. This access is rather a supplement that is allowed by using system Linux, as greater part of necessary features is realized using the enigma2 GUI application or by plugins.
Technical realization
Enigma2 application implements a Graphical user interface (GUI) to control DVB receivers; it does not use X Window System for graphic output as is usual on Linux systems, but direct access to framebuffer; to run it makes use the Linux kernel and environment, usually in lightweight versions (BusyBox, Dropbear (software), etc.), for software build OpenEmbedded (OE) environment is used. The configuration of the features necessary to manage the system is realized in the form of menu and text dialogues. The Enigma2 core is written in the programming language C++ and creates an API for plugins written in Python (programming language). Tutorials are available on the satsupreme.com website about plugin development including the source code of simple plugins.
See also
E2 Linux
Digital Video Broadcasting
Tuner (radio)
Set-top box
Hybrid Broadcast Broadband TV
Digital video recorder
Streaming media
References
External links
Base web for Enigma2
Satellite television
Set-top box
Television technology
Linux-based devices
Software related to embedded Linux | Enigma (DVB) | [
"Technology"
] | 2,481 | [
"Information and communications technology",
"Television technology"
] |
68,595,679 | https://en.wikipedia.org/wiki/Phylogenetic%20signal | Phylogenetic signal is an evolutionary and ecological term, that describes the tendency or the pattern of related biological species to resemble each other more than any other species that is randomly picked from the same phylogenetic tree.
Characteristics
Phylogenetic signal is usually described as the tendency of related biological species to resemble each other more than any other species that is randomly picked from the same phylogenetic tree. In other words, phylogenetic signal can be defined as the statistical dependence among species' trait values that is a consequence of their phylogenetic relationships. The traits (e.g. morphological, ecological, life-history or behavioural traits) are inherited characteristics – meaning the trait values are usually alike within closely related species, while trait values of distantly related biological species do not resemble each other to a such great degree. It is often said that traits that are more similar in closely related taxa than in distant relatives exhibit greater phylogenetic signal. On the other hand, some traits are a consequence of convergent evolution and appear more similar in distantly related taxa than in relatives. Such traits show lower phylogenetic signal.
Phylogenetic signal is a measure, closely related with an evolutionary process and development of taxa. It is thought that high rate of evolution leads to low phylogenetic signal and vice versa (hence, high phylogenetic signal is usually a consequence of either low rate of evolution either stabilizing type of selection). Similarly high value of phylogenetic signal results in an existence of similar traits between closely related biological species, while increasing evolutionary distance between related species leads to decrease in similarity. With a help of phylogenetic signal we can quantify to what degree closely related biological taxa share similar traits.
On the other hand, some authors advise against such interpretations (the ones based on estimates of phylogenetic signal) of evolutionary rate and process. While studying simple models for quantitative trait evolution, such as the homogeneous rate genetic drift, it appears to be no relation between phylogenetic signal and rate of evolution. Within other models (e.g. functional constraint, fluctuating selection, phylogenetic niche conservatism, evolutionary heterogeneity etc.) relations between evolutionary rate, evolutionary process and phylogenetic signal are more complex, and can not be easily generalized using mentioned perception of the relation between two phenomenons. Some authors argue that phylogenetic signal is not always strong in each clade and for each trait. It is also not clear if all of the possible traits do exhibit phylogenetic signal and if it is measurable.
Aim and methodology
Goal
Phylogenetic signal is a concept widely used in different ecological and evolutionary studies.
Among many questions that can be answered using a concept of phylogenetic signal, the most common ones are:
To what degree are investigated traits in correlation?
How, when and why do certain traits evolve?
Which processes are the driving force of community assembly?
Do niches get conserved along phylogenies?
Is there any relation between vulnerability to climate change and taxa phylogeny?
Techniques
Quantifying phylogenetic signal can be done using a range of various methods that are used for researching biodiversity in an aspect of evolutionary relatedness. With a help of measuring phylogenetic signal one can determine exactly how studied traits are correlated with phylogenetic relationship between species.
Some of the earliest ways of quantifying phylogenetic signal were based on the use of various statistical methods (such as phylogenetic autocorrelation coefficients, phylogenetic correlograms, as well as autoregressive models). With a help of the mentioned methods one is able to quantify the value of phylogenetic autocorrelation for a studied trait throughout the phylogeny. Another method commonly used in studying phylogenetic signal is so-called Brownian diffusion model of trait evolution that is based on the Brownian motion (BM) principle. Using Brownian diffusion model, one can not only study values but also compare those measures between various phylogenies. Phylogenetic signal in continuous traits can be quantified and measured using K-statistic. Within this technique values from zero to infinity are used and higher value also means greater level of phylogenetic signal.
The table below shows the most common indices and associated tests used for analyzing phylogenetic signal.
See also
Phylogenetic niche conservatism
Phylogenetic comparative methods
References
Biodiversity
Phylogenetics | Phylogenetic signal | [
"Biology"
] | 836 | [
"Bioinformatics",
"Phylogenetics",
"Taxonomy (biology)",
"Biodiversity"
] |
68,597,317 | https://en.wikipedia.org/wiki/Republic%20Stamping%20and%20Enameling | Republic Stamping and Enameling was an enamelware manufacturing company in Canton, Ohio. It operated from 1907 until 1952 when it was purchased by Ecko Products of Chicago. The company was founded by a group of investors led by Henry C. Milligan (1853–1940), an inventor who held several patents for improvements in enamelware manufacturing.
Founder
Milligan, a New Jersey native whose father was secretary-treasurer of the Central Railroad of New Jersey, had worked in a variety of metalworking factories, founded the company after working at the Carnahan Stamping & Enameling Co. in Canton, which he had helped found. Milligan was granted a patent in 1884 for one-coat granite ware that would serve as a basis for some of the processes at the company. He also obtained a patent in 1904 for enameling steelware that provided a smoother finish. Milligan was involved in many other civic and business interests in Northeast Ohio, including serving for many years as a director of National City bank of Cleveland. Milligan also chaired a Congressionally-appointed committee that studied the enamelware industry globally after World War I and recommended steep tariffs to protect U.S. plants such as his own.
History and growth
The Republic Enameling Plant initially employed 300 people at a new facility along a rail line at Harrison Ave S.W. and Navarre Road. The company enjoyed robust sales shortly after opening and several real estate developments were launched in the area to house workers, many of whom were European immigrants or had relocated from rural areas. In 1915, Republic Stamping purchased the General Stamping Co. of Canton for $1 million and was able to increase production to 160,000 pieces of enamelware daily. Republic operated the acquisition as an separate plant on the east side of Canton until closing it two years later and consolidating all production at its main location. In 1918, the company completed the addition of 184,000 square feet of floor space in two new facilities, including a conveyor belt system that eliminated miles of manual hauling by workers daily. By that year, Republic Stamping employed 1,000 people and was devoted to World War I government contracts for hospital and mess utensils. By the 1920s – boosted by tariffs that blunted competition from European manufacturers – the company was shipping pots, pans and other affordable kitchen utensils via rail throughout the country, including under the Old English Gray Ware brand.
Republic continued to refine its production processes, replacing coal with oil to power the facility and improving the grounds around the plant to make them more attractive for workers on lunch breaks. Heavy activity at Republic Stamping plant also led to frequent blockages of Harrison Ave. S.W. as trains waited for loading at the factory. This led to the eventual construction of an underpass at that location.
The company was headquartered on the seventh floor of the new First National Bank Building in downtown Canton, which opened in 1924.
From the beginning, Republic Stamping employed many women, especially in the dipping department where pans were coated in liquid enamel, a task considered best suited to female manual dexterity.
The company was unusual in that it gave employees a Christmas bonus of life insurance equal to their annual salary. Like many other Canton-area employers, Republic Stamping also hosted an annual summer picnic for employees at Myers Lake. Labor relations were generally congenial, although there was a brief wildcat strike in 1933 and a walkout in 1941. Republic was represented by the American Federation of Labor’s Council of Fabricated Metal, Dairy Gasoline Utensil & Enamel Workers local of the American Federation of Labor until the United Steelworkers of America became the representative after the company was sold.
The Second World War and decline
During the Second World War, Republic converted to war production and produced canteens, powder cartridges and other items. In 1944, Republic received the Army-Navy “E” award for excellence in the production of war materials.
Throughout its history, the company had expanded into many product lines ranging from Christmas tree holders to aluminum boxes used to haul bulk products at grocery stores.
But with consumer tastes and new materials capturing the houseware market, Ecko Products Inc. bought out Republic Stamping owners and the 400,000-square-foot facility in May, 1952. A few months later Ecko transferred the manufacturing of Ovenex tinware to the Canton plant and dropped enamel production. The plant closed in 1959 with the transfer of housewares production to a sister facility in Massillon. The Canton plant would reopen in 1961. Ecko ceased operations at the Republic site in 1986. The building still stands.
Photo album
Life in the Republic Stamping plant during the mid-1940s is captured in an extensive photo album created by employee Charles Doyne Reese. The 1,400 photos show workers doing their daily tasks plus special events like Christmas parties and the annual summer picnic at Myers Lake.
The album is now part of the William McKinley Presidential Library and Museum.
References
1907 establishments in Ohio
1952 disestablishments in Ohio
Companies based in Canton, Ohio
Manufacturing companies established in 1907
Manufacturing companies disestablished in 1952
Photographic collections
Vitreous enamel | Republic Stamping and Enameling | [
"Chemistry"
] | 1,039 | [
"Coatings",
"Vitreous enamel"
] |
68,597,435 | https://en.wikipedia.org/wiki/COVID-19%20vaccine%20clinical%20research | COVID-19 vaccine clinical research uses clinical research to establish the characteristics of COVID-19 vaccines. These characteristics include efficacy, effectiveness, and safety. , 40 vaccines are authorized by at least one national regulatory authority for public use:
one DNA vaccine: ZyCoV-D
four RNA vaccines: Pfizer–BioNTech, Moderna, Walvax, and Gemcovac
twelve inactivated vaccines: Chinese Academy of Medical Sciences, CoronaVac, Covaxin, CoviVac, COVIran Barekat, FAKHRAVAC, Minhai-Kangtai, QazVac, Sinopharm BIBP, WIBP, Turkovac, and VLA2001.
six viral vector vaccines: Sputnik Light, Sputnik V, Oxford–AstraZeneca, Convidecia, Janssen, and iNCOVACC
sixteen subunit vaccines: Abdala, Corbevax, COVAX-19, EpiVacCorona, IndoVac, MVC-COV1901, Noora, Novavax, Razi Cov Pars, Sanofi–GSK, Sinopharm CNBG, Skycovione, Soberana 02, Soberana Plus, V-01, and ZF2001.
one virus-like particle vaccine: CoVLP
, 353 vaccine candidates are in various stages of development, with 135 in clinical research, including 38 in phase I trials, 32 in phase I–II trials, 39 in phase III trials, and 9 in phase IV development.
Formulation
A wide variety of technologies are being used to formulate vaccines against COVID-19. The development and deployment of mRNA vaccines and viral vector vaccines has been outstandingly rapid and can be described as revolutionary. However, global vaccine equity against COVID-19 has not been achieved. Conventional vaccine manufacturing approaches using whole inactivated virus (WIV), protein-based subunit vaccines, and virus-like particles (VLPs) may offer advantages in the development of vaccines for use in low- and middle-income countries (LMICs) and in addressing vaccine access gaps.
Many vaccine candidates use adjuvants to enhance immunogenicity, as part of the delivery system or as an accompanying immune stimulant. Vaccine adjuvant formulations using aluminum salts or "alum" may be particularly effective for technologies using inactivated COVID-19 virus and for recombinant protein-based or vector-based vaccines.
Status
Clinical trials
The clinical trial process typically consists of three phases, each following the success of the prior phase. Trials are doubly blind in that neither the researcher nor the subject know whether they receive the vaccine or a placebo. Each phase involves randomly-selected subjects who are randomly assigned to serve either as recipients are controls:
Phase I trials test primarily for safety and preliminary dosing in healthy subjects. Dozens of subjects.
Phase II trials evaluate immunogenicity, dose levels (efficacy based on biomarkers) and adverse effects. Hundreds of subjects. Sometimes Phase I and II trials are combined.
Phase III trials typically involve more participants at multiple sites, include a control group, and test effectiveness of the vaccine to prevent the disease (an "interventional" or "pivotal" trial), while monitoring for adverse effects at the selected dose. Safety, efficacy, and clinical endpoints may vary, including the definition of side effects, infection or amount of transmission, and whether the vaccine prevents moderate or severe infection.
A clinical trial design in progress may adopt an "adaptive design". If accumulating data provide insights about the treatment, the endpoints or other aspects or the trial can be adjusted. Adaptive designs may shorten trial durations and use fewer subjects, possibly expediting decisions, avoiding duplication of research efforts, and enhancing coordination of design changes.
Vaccine candidates in human trials
The table below shows various vaccine candidates and the phases which they had completed per the references. Current phases are also shown along with other details.
Homologous prime-boost vaccination
In July 2021, the U.S. Food and Drug Administration (FDA) and the Centers for Disease Control and Prevention (CDC) issued a joint statement reporting that a booster dose is not necessary for those who have been fully vaccinated.
In August 2021, the FDA and the CDC authorized the use of an additional mRNA vaccine dose for immunocompromised individuals. The authorization was extended to cover other specific groups in September 2021.
In October 2021, the FDA and the CDC authorized the use of either homologous or heterologous vaccine booster doses.
Heterologous prime-boost vaccination
The World Health Organization (WHO) defines heterologous prime-boost immunization as the "administration of two different vectors or delivery systems expressing the same or overlapping antigenic inserts." A heterologous scheme can sometimes be more immunogenic than some homologous schemes.
In October 2021, the FDA and the CDC authorized the use of either homologous or heterologous vaccine booster doses.
Some experts believe that heterologous prime-boost vaccination courses can boost immunity, and several studies have begun to examine this effect. Despite the absence of clinical data on the efficacy and safety of such heterologous combinations, Canada and several European countries have recommended a heterologous second dose for people who have received the first dose of the Oxford–AstraZeneca vaccine.
In February 2021, the Oxford Vaccine Group launched the Com-COV vaccine trial to investigate heterologous prime-boost courses of different COVID-19 vaccines. As of June 2021, the group is conducting two phase II studies: Com-COV and Com-COV2.
In Com-COV, the two heterologous combinations of the Oxford–AstraZeneca and Pfizer–BioNTech vaccines were compared with the two homologous combinations of the same vaccines, with an interval of 28 or 84 days between doses.
In Com-COV2, the first dose is the Oxford–AstraZeneca vaccine or the Pfizer vaccine, and the second dose is the Moderna vaccine, the Novavax vaccine, or a homologous vaccine equal to the first dose, with an interval of 56 or 84 days between doses.
A study in the UK is evaluating annual heterologous boosters by randomly combining the following vaccines: Oxford–AstraZeneca, Pfizer–BioNTech, Moderna, Novavax, VLA2001, CureVac, and Janssen.
On 16 December, WHO recommendations on heterologous vaccinations suggested a general trend of increased immunogenicity when one of the doses is of an mRNA vaccine, particularly as the last dose. The immunogenicity of a homologous mRNA course is roughly equivalent to a heterologous scheme involving a vector vaccine and an mRNA vaccine. However, the WHO has emphasized the need to address many evidence gaps in heterologous regimens, including duration of protection, optimal interval between doses, influence of fractional dosing, effectiveness against variants and long-term safety.
Efficacy
Vaccine efficacy is the reduction in risk of getting the disease by vaccinated participants in a controlled trial compared with the risk of getting the disease by unvaccinated participants. An efficacy of 0% means that the vaccine does not work (identical to placebo). An efficacy of 50% means that there are half as many cases of infection as in unvaccinated individuals.
COVID-19 vaccine efficacy may be adversely affected if the arm is held improperly or squeezed so the vaccine is injected subcutaneously instead of into the muscle. The CDC guidance is to not repeat doses that are administered subcutaneously.
It is not straightforward to compare the efficacies of the different vaccines because the trials were run with different populations, geographies, and variants of the virus. In the case of COVID-19 prior to the advent of the delta variant, it was thought that a vaccine efficacy of 67% may be enough to slow the pandemic, but the current vaccines do not confer sterilizing immunity, which is necessary to prevent transmission. Vaccine efficacy reflects disease prevention, a poor indicator of transmissibility of SARS‑CoV‑2 since asymptomatic people can be highly infectious. The US Food and Drug Administration (FDA) and the European Medicines Agency (EMA) set a cutoff of 50% as the efficacy required to approve a COVID-19 vaccine, with the lower limit of the 95% confidence interval being greater than 30%. Aiming for a realistic population vaccination coverage rate of 75%, and depending on the actual basic reproduction number, the necessary effectiveness of a COVID-19 vaccine is expected to need to be at least 70% to prevent an epidemic and at least 80% to extinguish it without further measures, such as social distancing.
The observed substantial efficacy of certain mRNA vaccines even after partial (1-dose) immunization indicates a non-linear dose-efficacy relation already seen in the phase I-II study. It suggests that personalization of the vaccine dose (regular dose to the elderly, reduced dose to the healthy young, additional booster dose to the immunosuppressed) might allow accelerating vaccination campaigns in settings of limited supplies, thereby shortening the pandemic, as predicted by pandemic modeling.
Ranges below are 95% confidence intervals unless indicated otherwise, and all values are for all participants regardless of age, according to the references for each of the trials. By definition, the accuracy of the estimates without an associated confidence interval is unknown publicly. Efficacy against severe COVID-19 is the most important, since hospitalizations and deaths are a public health burden whose prevention is a priority. Authorized and approved vaccines have shown the following efficacies:
Effectiveness
Evidence from vaccine use during the pandemic shows vaccination can reduce infection and is most effective at preventing severe COVID-19 symptoms and death, but is less good at preventing mild COVID-19. Efficacy wanes over time but can be maintained with boosters. In 2021, the CDC reported that unvaccinated people were 10 times more likely to be hospitalized and 11 times more likely to die than fully vaccinated people.
The CDC reported that vaccine effectiveness fell from 91% against Alpha to 66% against Delta. One expert stated that "those who are infected following vaccination are still not getting sick and not dying like was happening before vaccination." By late August 2021, the Delta variant accounted for 99 percent of U.S. cases and was found to double the risk of severe illness and hospitalization for those not yet vaccinated.
In November 2021, a study by the ECDC estimated that 470,000 lives over the age of 60 had been saved since the start of the vaccination roll-out in the European region. According to a June 2022 study, COVID19 vaccines prevented an additional 14.4 to 19.8 million deaths in 185 countries and territories from 8 December 2020 to 8 December 2021.
On 10 December 2021, the UK Health Security Agency reported that early data indicated a 20- to 40-fold reduction in neutralizing activity for Omicron by sera from Pfizer 2-dose vaccinees relative to earlier strains. After a booster dose (usually with an mRNA vaccine), vaccine effectiveness against symptomatic disease was at , and the effectiveness against severe disease was expected to be higher.
According to early December 2021 CDC data, "unvaccinated adults were about 97 times more likely to die from COVID-19 than fully vaccinated people who had received boosters".
A meta-analysis looking into COVID-19 vaccine differences in immunosuppressed individuals found that people with a weakened immune system are less able to produce neutralizing antibodies. For example, organ transplant recipients need three vaccines to achieve seroconversion. A study on the serologic response to mRNA vaccines among patients with lymphoma, leukemia, and myeloma found that one-quarter of patients did not produce measurable antibodies, varying by cancer type.
In February 2023, a systematic review in The Lancet said that the protection afforded by infection was comparable to that from vaccination, albeit with an increased risk of severe illness and death from the disease of an initial infection.
A January 2024 study by the CDC found that staying up to date on the vaccines could reduce the risk of strokes, blood clots and heart attacks related to COVID-19 in people aged 65 years or older or with a condition that makes them more vulnerable to said conditions.
Studies
Real-world studies of vaccine effectiveness measure the extent to which a certain vaccine prevents infection, symptoms, hospitalization and death for the vaccinated individuals in a large population under routine conditions.
In Israel, among the 715,425 individuals vaccinated by the mRNA vaccines from 20 December 2020, to 28 January 2021, starting seven days after the second shot, only 317 people (0.04%) displayed mild/moderate COVID-19 symptoms and only 16 people (0.002%) were hospitalized.
CDC reported that under real-world conditions, mRNA vaccine effectiveness was 90% against infections regardless of symptom status; while effectiveness of partial immunization was 80%.
In the UK, 15,121 health care workers from 104 hospitals who had tested negative for antibodies prior to the study, were followed by RT-PCR tests twice a week from 7 December 2020 to 5 February 2021, a study compared the positive results for the 90.7% vaccinated share of their cohort with the 9.3% unvaccinated share, and found that the Pfizer-BioNTech vaccine reduced all infections (including asymptomatic), by 72% (58–86%) three weeks after the first dose and 86% (76–97%) one week after the second dose, while Alpha was dominant.
In Israel a study conducted from 17 January to 6 March 2021, found that Pfizer/BioNTech reduced asymptomatic Alpha infections by 94% and symptomatic COVID-19 infections by 97%.
A study on the Queensland Population having only ever been exposed to the Omicron strain of COVID-19 found vaccine effectiveness against symptomatic hospitalizations to be 70% in the general population and similar for First Nations peoples.
A study among pre-surgical patients across the Mayo Clinic system in the United States, showed that mRNA vaccines were 80% protective against asymptomatic infections.
A UK study found that a single dose of the Oxford–AstraZeneca COVID-19 vaccine is about effective in people aged 70 and older.
A study finds that nearly all teenagers admitted to intensive care units because of COVID-19 were unvaccinated.
Pregnancy and fertility
Studies have not observed a correlation between COVID vaccination and fertility.
A UK study found COVID vaccination is safe for pregnant women and is associated with a 15% decrease in the odds of stillbirth. Vaccination is recommended for pregnant women because pregnancy increases the risk of severe COVID. Researchers at St George's, University of London, and the Royal College of Obstetricians and Gynaecologists investigated 23 published studies and trials involving 117,552 vaccinated pregnant women. There was no increased risk of complications during pregnancy. Almost all pregnant women admitted to UK hospitals with COVID were unvaccinated.
A US study of 46,079 pregnancies concluded that COVID vaccination is safe and does not raise the risk of preterm birth or small size babies.
Variants
The interplay between the SARS-CoV-2 virus and its human hosts was initially natural but is now being altered by the prompt availability of vaccines. The potential emergence of a SARS-CoV-2 variant that is moderately or fully resistant to the antibody response elicited by the COVID-19 vaccines may necessitate modification of the vaccines. The emergence of vaccine-resistant variants is more likely in a highly vaccinated population with uncontrolled transmission. Trials indicate many vaccines developed for the initial strain have lower efficacy for some variants against symptomatic COVID-19. , the US Food and Drug Administration believed that all FDA authorized vaccines remained effective in protecting against circulating strains of SARS-CoV-2.
Alpha (lineage B.1.1.7)
Limited evidence from various preliminary studies reviewed by the WHO indicated retained efficacy/effectiveness against disease from Alpha with the Oxford–AstraZeneca vaccine, Pfizer–BioNTech and Novavax, with no data for other vaccines yet. Relevant to how vaccines can end the pandemic by preventing asymptomatic infection, they have also indicated retained antibody neutralization against Alpha with most of the widely distributed vaccines (Sputnik V, Pfizer–BioNTech, Moderna, CoronaVac, Sinopharm BIBP, Covaxin), minimal to moderate reduction with the Oxford–AstraZeneca and no data for other vaccines yet.
In December 2020, a new SARS‑CoV‑2 variant, the Alpha variant or lineage B.1.1.7, was identified in the UK.
Early results suggest protection to the variant from the Pfizer-BioNTech and Moderna vaccines.
One study indicated that the Oxford–AstraZeneca COVID-19 vaccine had an efficacy of 42–89% against Alpha, versus 71–91% against other variants.
Preliminary data from a clinical trial indicates that the Novavax vaccine is ~96% effective for symptoms against the original variant and ~86% against Alpha.
Beta (lineage B.1.351)
Limited evidence from various preliminary studies reviewed by the WHO have indicated reduced efficacy/effectiveness against disease from Beta with the Oxford–AstraZeneca vaccine (possibly substantial), Novavax (moderate), Pfizer–BioNTech and Janssen (minimal), with no data for other vaccines yet. Relevant to how vaccines can end the pandemic by preventing asymptomatic infection, they have also indicated possibly reduced antibody neutralization against Beta with most of the widely distributed vaccines (Oxford–AstraZeneca, Sputnik V, Janssen, Pfizer–BioNTech, Moderna, Novavax; minimal to substantial reduction) except CoronaVac and Sinopharm BIBP (minimal to modest reduction), with no data for other vaccines yet.
Moderna has launched a trial of a vaccine to tackle the Beta variant or lineage B.1.351. On 17 February 2021, Pfizer announced neutralization activity was reduced by two-thirds for this variant, while stating that no claims about the efficacy of the vaccine in preventing illness for this variant could yet be made. Decreased neutralizing activity of sera from patients vaccinated with the Moderna and Pfizer-BioNTech vaccines against Beta was later confirmed by several studies. On 1 April 2021, an update on a Pfizer/BioNTech South African vaccine trial stated that the vaccine was 100% effective so far (i.e., vaccinated participants saw no cases), with six of nine infections in the placebo control group being the Beta variant.
In January 2021, Johnson & Johnson, which held trials for its Janssen vaccine in South Africa, reported the level of protection against moderate to severe COVID-19 infection was 72% in the United States and 57% in South Africa.
On 6 February 2021, the Financial Times reported that provisional trial data from a study undertaken by South Africa's University of the Witwatersrand in conjunction with Oxford University demonstrated reduced efficacy of the Oxford–AstraZeneca COVID-19 vaccine against the variant. The study found that in a sample size of 2,000 the AZD1222 vaccine afforded only "minimal protection" in all but the most severe cases of COVID-19. On 7 February 2021, the Minister for Health for South Africa suspended the planned deployment of about a million doses of the vaccine whilst they examine the data and await advice on how to proceed.
In a study reported in March and May 2021, the efficacy of the Novavax vaccine (NVX-CoV2373) was tested in a preliminary randomized, placebo-controlled study involving 2684 participants who were negative for COVID at baseline testing. Beta was the predominant variant to occur, with post-hoc analysis indicating a vaccine efficacy of Novavax against Beta of 51.0% for HIV-negative participants.
Gamma (lineage P.1)
Limited evidence from various preliminary studies reviewed by the WHO have indicated likely retained efficacy/effectiveness against disease from Gamma with CoronaVac and Sinopharm BIBP, with no data for other vaccines yet. Relevant to how vaccines can end the pandemic by preventing asymptomatic infection, they have also indicated retained antibody neutralization against Gamma with Oxford–AstraZeneca and CoronaVac (no to minimal reduction) and slightly reduced neutralization with Pfizer–BioNTech and Moderna (minimal to moderate reduction), with no data for other vaccines yet.
The Gamma variant or lineage P.1 variant (also known as 20J/501Y.V3), initially identified in Brazil, seems to partially escape vaccination with the Pfizer-BioNTech vaccine.
Delta (lineage B.1.617.2)
Limited evidence from various preliminary studies reviewed by the WHO have indicated likely retained efficacy/effectiveness against disease from Delta with the Oxford–AstraZeneca vaccine and Pfizer–BioNTech, with no data for other vaccines yet. Relevant to how vaccines can end the pandemic by preventing asymptomatic infection, they have also indicated reduced antibody neutralization against Delta with single-dose Oxford–AstraZeneca (substantial reduction), Pfizer–BioNTech and Covaxin (modest to moderate reduction), with no data for other vaccines yet.
In October 2020, a new variant was discovered in India, which was named lineage B.1.617. There were very few detections until January 2021, but by April it had spread to at least 20 countries in all continents except Antarctica and South America. Mutations present in the spike protein in the B.1.617 lineage are associated with reduced antibody neutralization in laboratory experiments. The variant has frequently been referred to as a 'Double mutant', even though in this respect it is not unusual. the latter two of which may cause it to easily avoid antibodies. In an update on 15 April 2021, PHE designated lineage B.1.617 as a 'Variant under investigation', VUI-21APR-01. On 6 May 2021, Public Health England escalated lineage B.1.617.2 from a Variant Under Investigation to a Variant of Concern based on an assessment of transmissibility being at least equivalent to the Alpha variant.
Omicron (lineage BA.2 and BA.2.12.2)
COVID-19 vaccine effectiveness was studied in adults without immunocompromising conditions in 10 US states between 18 December 2021 – 10 June 2022, when Omicron was prevalent. 3 doses of mRNA COVID-19 vaccines was 69% against COVID-19–associated hospitalization 7–119 days after the third vaccine dose and 52% against COVID-19–associated hospitalization more than 4 months after the 3rd dose. Among adults aged ≥50 years, COVID-19 vaccine effectiveness against COVID-19–associated hospitalization ≥120 days after receipt of dose 3 was only 32%, increasing to 66% ≥7 days after the fourth dose.
Effect of neutralizing antibodies
One study found that the in vitro concentration (titer) of neutralizing antibodies elicited by a COVID-19 vaccine is a strong correlate of immune protection. The relationship between protection and neutralizing activity is nonlinear. A neutralization as low as of the level of convalescence results in 50% efficacy against severe disease, with resulting in 50% efficacy against detectable infection. Protection against infection quickly decays, leaving individuals susceptible to mild infections, while protection against severe disease is largely retained and much more durable. The observed half-life of neutralizing titers was 65 days for mRNA vaccines (Pfizer–BioNTech, Moderna) during the first 4 months, increasing to 108 days over 8 months. Greater initial efficacy against infection likely results in a higher level of protection against serious disease in the long term (beyond 10 years, as seen in other vaccines such as smallpox, measles, mumps, and rubella), although the authors acknowledge that their simulations consider only protection from neutralizing antibodies and ignore other immune protection mechanisms, such as cell-mediated immunity, which may be more durable. This observation also applies to efficacy against variants and is particularly significant for vaccines with a lower initial efficacy; for example, a 5-fold reduction in neutralization would indicate a reduction in initial efficacy from 95% to 77% against a specific variant, and from a lower efficacy of 70% to 32% against that variant. For the Oxford–AstraZeneca vaccine, the observed efficacy is below the predicted 95% confidence interval. It is higher for Sputnik V and the convalescent response, and is within the predicted interval for the other vaccines evaluated (Pfizer–BioNTech, Moderna, Janssen, CoronaVac, Covaxin, Novavax).
Drug interactions
Methotrexate reduces the immune response to COVID-19 vaccines, making them less effective. Pausing methotrexate for two weeks following COVID-19 vaccination may result in improved immunity. Not taking the medicine for two weeks might result in a minor increase of inflammatory disease flares in some people.
Side effects
All vaccines, including COVID-19 ones, can have minor side effects related to the mild trauma associated with the introduction of a foreign substance into the body. These include soreness, redness, rash, and inflammation at the injection site. Other common side effects include fatigue, headache, myalgia (muscle pain), and arthralgia (joint pain) which generally resolve within a few days.
Serious adverse events that follow the administration of vaccines are of high interest to the public. It is important to recognize that the occurrence of an adverse event following vaccination does not necessarily mean that the vaccine caused the adverse event; the health problem may have been unrelated. Reporting of all adverse events, careful followup and statistical analysis of occurrences are required to determine whether or not a specific health problem is more likely to occur after a vaccine is administered.
More serious side effects are very rare. Before COVID-19 vaccines such as Moderna and Pfizer/BioNTech were authorized for use in the general population, they had to pass phase III studies involving tens of thousands of people. Any serious side effects that did not appear during that testing are likely to occur less often than ~1 in 10,000 cases. It is important that Phase III trials be diverse, to ensure that safety results apply broadly. It is possible that side effects may affect a population that was not adequately represented during the initial testing. Pregnant women, immunocompromised people, and children are usually excluded from initial studies because they may be at higher risk. Further studies may be done to ensure their safety before vaccines are authorized for use in such populations. Subsequent examinations of the use of COVID vaccines in pregnant people and in children have shown similar outcomes to the general population and do not suggest greater risk for these groups.
References
Virus research | COVID-19 vaccine clinical research | [
"Biology"
] | 5,722 | [
"Viruses",
"Virus research"
] |
68,597,933 | https://en.wikipedia.org/wiki/Zhilan%20Feng | Zhilan Julie Feng (born 1959) is a Chinese-American applied mathematician whose research topics include mathematical biology, population dynamics, and epidemiology. She is a professor of mathematics at Purdue University, and a program director in the Division of Mathematical Sciences at the National Science Foundation.
Education and career
Feng studied mathematics at Jilin University in China, earning a bachelor's degree in 1982 and a master's degree in 1985. She came to Arizona State University for graduate study, completing her Ph.D. in 1994. Her dissertation, A Mathematical Model for the Dynamics of Childhood Diseases Under the Impact of Isolation, was supervised by Horst R. Thieme.
After her postdoctoral study at Cornell University, she joined Purdue University as an assistant professor in 1996. She was promoted to full professor in 2005, and became a program director at the National Science Foundation in 2019.
Recognition
Feng was named a Fellow of the American Mathematical Society, in the 2022 class of fellows, "for contributions to applied mathematics, particularly in biology, ecology, and epidemiology".
Books
Feng's books include:
Disease Evolution: Models, Concepts, and Data Analyses (American Mathematical Society, 2006, edited with Ulf Dieckmann and Simon A. Levin)
Applications of Epidemiological Models to Public Health Policymaking: The role of heterogeneity in model predictions (World Scientific, 2014)
Mathematical Models of Plant-Herbivore Interactions (Chapman & Hall / CRC, 2018, with Donald DeAngelis)
Mathematical Models in Epidemiology (Springer, 2019, with Fred Brauer and Carlos Castillo-Chavez)
References
External links
Home page
1959 births
Living people
Chinese biologists
Chinese epidemiologists
Chinese mathematicians
Chinese women biologists
Chinese women mathematicians
American biologists
American epidemiologists
20th-century American mathematicians
21st-century American mathematicians
American women biologists
American women epidemiologists
Applied mathematicians
Theoretical biologists
Jilin University alumni
Cornell University alumni
Purdue University faculty
United States National Science Foundation officials
Fellows of the American Mathematical Society
20th-century American women mathematicians
21st-century American women mathematicians | Zhilan Feng | [
"Mathematics",
"Biology"
] | 425 | [
"Bioinformatics",
"Applied mathematics",
"Applied mathematicians",
"Theoretical biologists"
] |
68,598,414 | https://en.wikipedia.org/wiki/SuanShu%20numerical%20library | SuanShu is a Java math library. It is open-source under Apache License 2.0 available in GitHub. SuanShu is a large collection of Java classes for basic numerical analysis, statistics, and optimization. It implements a parallel version of the adaptive strassen's algorithm for fast matrix multiplication. SuanShu has been quoted and used in a number of academic works.
Features
linear algebra
root finding
curve fitting and interpolation
unconstrained and constrained optimization
statistical analysis
linear regression
probability distributions and random number generation
ordinary and partial differential equation solvers
License terms
SuanShu is released under the terms of the Apache License 2.0
Examples of usage
The following code shows the object-oriented design of the library (in contrast to the traditional procedural design of many other FORTRAN and C numerical libraries) by a simple example of minimization.
LogGamma logGamma = new LogGamma(); // the log-gamma function
BracketSearchMinimizer solver = new BrentMinimizer(1e-8, 10); // precision, max number of iterations
UnivariateMinimizer.Solution soln = solver.solve(logGamma); // optimization
double x_min = soln.search(0, 5); // bracket = [0, 5]
System.out.println(String.format("f(%f) = %f", x_min, logGamma.evaluate(x_min)));
See also
SOCP - Explanation of Second Order Conic Programming
SDP - Explanation of Semidefinite Programming
SQP - Explanation of Sequential quadratic programming
Interior Point Method
Adaptive strassen's algorithm – fast matrix multiplication
Apache License 2.0 - Version 2 of the Apache Software License
References
Numerical libraries
Java (programming language) libraries
Public-domain software with source code
Numerical software | SuanShu numerical library | [
"Mathematics"
] | 392 | [
"Numerical software",
"Mathematical software"
] |
68,598,568 | https://en.wikipedia.org/wiki/Beyond%20Infinity%20%28mathematics%20book%29 | Beyond Infinity : An Expedition to the Outer Limits of Mathematics is a popular mathematics book by Eugenia Cheng centered on concepts of infinity. It was published by Basic Books and (with a slightly different title) by Profile Books in 2017, and in a paperback edition in 2018. It was shortlisted for the 2017 Royal Society Insight Investment Science Book Prize.
Topics
The book is divided into two parts, with the first exploring notions leading to concepts of actual infinity, concrete but infinite mathematical values. After an exploration of number systems, this part discusses set theory, cardinal numbers, and ordinal numbers, transfinite arithmetic, and the existence of different infinite sizes of sets. Topics used to illustrate these concepts include Hilbert's paradox of the Grand Hotel, Cantor's diagonal argument, and the unprovability of the continuum hypothesis.
The second part concerns mathematics related to the idea of potential infinity, the assignment of finite values to the results of infinite processes including growth rates, limits, and infinite series. This part also discusses Zeno's paradoxes, Dedekind cuts, the dimensions of spaces, and the possibility of spaces of infinite dimensions, with a mention of higher category theory, Cheng's research specialty.
The mathematics is frequently lightened and made accessible with personal experiences and stories, involving such subjects as the Loch Ness Monster, puff pastry, boating, dance contests, shoes, "Legos, the iPod Shuffle, snorkeling, Battenberg cakes and Winnie-the-Pooh".
Audience and reception
The Royal Society judges called Beyond Infinity "a very engaging introduction to a forbidding subject". Similarly, reviewer Anne Haworth calls it "engaging and readable", and Wall Street Journal reviewer Sam Kean writes that its "chatty tone keeps things fresh". It is aimed at a popular audience, not assumed to have a significant background in mathematics, including "the young or those brimming with curiosity" as well as college or secondary-school students, although it may be "too elementary for mathematicians or mathematics students".
As similar reading material, reviewer Andrew James Simoson suggests placing this book alongside The Book of Numbers by John Horton Conway and Richard K. Guy (1996),
One Two Three... Infinity by George Gamow (1947), and Really Big Numbers by Richard Schwartz (2014).
References
Popular mathematics books
2017 non-fiction books
Infinity
Basic Books books
Profile Books books | Beyond Infinity (mathematics book) | [
"Mathematics"
] | 491 | [
"Mathematical objects",
"Infinity"
] |
68,598,894 | https://en.wikipedia.org/wiki/5-MeO-DBT | 5-MeO-DBT (5-Methoxy-N,N-dibutyltryptamine, 5-MeO-BET) is a rare substituted tryptamine derivative, which is thought to be a psychoactive substance and was identified in a designer drug sample by a forensic laboratory in Slovenia in March 2021, although only analytical studies have been conducted and no pharmacological data is available. It is nevertheless controlled under drug analogue legislation in a number of jurisdictions.
Legal status
5-MeO-DBT was made schedule I at the state level in Alabama on September 13th, 2024.
See also
Dibutyltryptamine
4-HO-DBT
4-HO-DSBT
5-MeO-DET
5-MeO-EPT
5-MeO-DPT
References
Tryptamines
Methoxy compounds | 5-MeO-DBT | [
"Chemistry"
] | 178 | [
"Pharmacology",
"Pharmacology stubs",
"Medicinal chemistry stubs"
] |
68,600,341 | https://en.wikipedia.org/wiki/Shrawan%20Danda | Shrawan Danda is a hill in the North-eastern part of Butwal city in Nepal. The hill is settled by about 10,000 residents. Geologically, the hill lies in the Siwalik region. The stability of the hill has been questioned by several researchers, however, the settlement has not been moved. The unstable zone of Shrawan Danda vulnerable to landslide has an area of about 1.5 km2. The altitude of the landslide zone from 200 to 750m and is covered by thin vegetation. There are several tension cracks on the crown. The zone is considered highly risky against earthquake due to presence of Main Frontal Thrust and Main Boundary Thrust in the immediate vicinity.
1998 landslide
The torrential rainfall on mid August 1998, triggered a landslide on 29 August and 5 September 1998. One person was killed in the landslide and five people were injured in the Jyotinagar and Laxminagar area. In total about 60 houses were damaged. The loss in infrastructure was calculated to be about NPR 58 millions.
2021 landslide
In August 2021 morning, landslide was triggered due to rainfall. About 11 houses were damaged by the landslide after it hit the settlement.
References
Natural disasters in Nepal
Landslides
Hills of Nepal | Shrawan Danda | [
"Environmental_science"
] | 247 | [
"Landslides",
"Environmental soil science"
] |
68,600,686 | https://en.wikipedia.org/wiki/WR%2069 | WR 69 is a Wolf–Rayet star located 11,350 light years away in the constellation of Triangulum Australe. It is classified as a WC9 star, belonging to the late-type carbon sequence. WR 69 is also a prolific dust maker, hence the "d" in its spectral type.
Binarity
WR 69 is mostly considered as a binary (WC9d+O star), with a supposed period of 2.293 days and an amplitude of 0.044 magnitudes, suggesting it could be a short period Colliding-Wind Binary. However, this period is not in fact due to binary, but due to the fast rotation of the WC9d star, which rotates quickly, once every 2.15 days, and at 40% of its breakup velocity. The WC9d star is likely part of a much longer binary system, hence the absorption lines found in its spectrum.
Properties
WR 69 is quite average for a WC9 star. Modelling WR 69's spectrum gives a temperature of 40,000 K, and a luminosity of ~214,000 L☉ is derived from Gaia DR2's parallax. From this a radius can be derived using the Stefan-Boltzmann Law, which turns out at just under 10 R☉. However, in the visual wavelength, the star is just 13,600 L☉ bright, because most of the 214,000 L☉ is emitted in the ultraviolet wavelength. WR 69 has 12.1 solar masses, but it likely started its life with much more than this, and lost much of it through its powerful stellar wind.
WR 69 has a very strong stellar wind, typical of Wolf-Rayet stars. WR 69 loses 10-4.87 M☉ (about ) per year because of this stellar wind, which has a terminal velocity of 1,089 kilometres per second.
References
Wolf–Rayet stars
075377
136488
Triangulum Australe | WR 69 | [
"Astronomy"
] | 405 | [
"Triangulum Australe",
"Constellations"
] |
68,600,733 | https://en.wikipedia.org/wiki/Aarne%20Heikinheimo | Aarne Silvio Heikinheimo (March 20, 1894 – January 24, 1938) was a Finnish Major General. He is well known for his service in the Finnish Civil War against the Red Guards.
Biography
Early life
Heikinheimo was born on March 20, 1894, in Tornio. His parents were chief forester Johan Henrik Heikel and Sally Armida Thauvón. He was married in 1919 to Sylvi Amalia Jurvelius. Heikinheimo enrolled as a student at the Finnish Co-educational School in Oulu in 1913 and joined the North Ostrobothnian Association. He continued his studies at the Department of Mechanical Engineering of the Helsinki University of Technology in 1913 to 1914. He followed teaching at the Military Academy Commander's Course in 1925 and attended the General Department of the Military Academy from 1926 to 1927.
World War I
Heikinheimo was one of the first volunteers to aim for a Pfadfinder military training course in Germany in the Lockstedter Lager training area in Northern Germany. He enrolled in the camp on February 25, 1915. He was placed in the 1st Company of the group. He was later stationed in the Royal, Prussian Jaeger Battalion in the 1st Company of the 27th. He took part in the fighting in the First World War on the eastern front of Germany on the Misse, the Gulf of Riga and the Aa. He attended the motorboat driver and machine gun station courses in Libya in the summer of 1917 and the car course in Schaulen in August 1917 and the blasting course in Libya in the autumn of 1917.
Finnish Civil War
He arrived in Finland with the command of the oberzugführer Friedel Jacobsson on January 30, 1918, and joined the Perä-Pohjola Conservation Corps in Tervola. He was seconded as a team leader in the battles against Tervola and Tornio. After the conquests of Tervola and Tornio, he was appointed Commander of the City of Kemi on February 7, until on March 5, he was appointed Commander of the Perä-Pohjola Battalion . He led his battalion to battles in Vilkkilä, Haavisto (Orivesi), Tervaniemi, Lempäälä, Vesilahti, Karku and Tyrvää. In the final stages of the Civil War, he was given the task of forming a regiment in Eastern Uusimaa in Lahti.
Life after the Civil War and death
After the Civil War, Heikinheimo was appointed Adjutant of the 1st Division as of July 1, 1918, and later interim Chief of Staff, from which he was transferred on 15 August 1918 as Commander of the Finnish White Guard I Battalion and further Commander on September 11, 1918, to the Vyborg Regiment II Battalion. Heikinheimo served as Chairman of the 2nd Division Court of Honor in 1920 and as Chairman of the 3rd Division Court of Honor in 1921 and 1925. He served as a member of the Bicycle Special Committee in 1922 He served as a member of the Winter Equipment Committee in 1924 and as chairman of the Field Equipment Committee from 1931 to 1934, and as chairman of the Bylaws Committee in 1934. He served as a member of the Mikkeli City Parish's extended church council from 1933 to 1934. He was promoted to commander of the Second Bicycle Battalion on April 27, 1921, and to commander of the Viborg Regiment on August 15, 1924. From August 12, 1926, he served as commander in the Jääkäri Brigade, from where he was promoted to Division 3 on June 9, and was assigned as an infantry inspector. He died accidentally in test firing at Harakka after the explosion of a grenade launcher pipe on January 24, 1938. He has been buried in Intiö Cemetery in Oulu, right next to the heroes' graves.
References
Bibliography
Publications of the Military History Office of the Ministry of Defense IV, Biography of Finnish Jaegers, WSOY Porvoo 1938.
Publications of the Department of Military Science XIV, Biography of Finnish Jaegers 1975, Vaasa 1975 ISBN 951-99046-8-9.
1894 births
1938 deaths
Accidental deaths in Finland
Deaths from explosion
Finnish officers
Jägers of the Jäger Movement
People from Tornio | Aarne Heikinheimo | [
"Chemistry"
] | 886 | [
"Deaths from explosion",
"Explosions"
] |
68,602,461 | https://en.wikipedia.org/wiki/Association%20for%20Materials%20Protection%20and%20Performance | The Association for Materials Protection and Performance (AMPP), is a professional association focused on the protection of assets and performance of materials. AMPP was created when NACE International and SSPC the Society for Protective Coatings merged in 2021. AMPP is active in more than 130 countries and has more than 40,000 members. AMPP is headquartered in the U.S. with offices in Houston, Texas and Pittsburgh, Pennsylvania. Additional offices are located in the U.K., China, Malaysia, Brazil, and Saudi Arabia with a training center in Dubai.
Standards
Both the legacy NACE and SSPC organizations were ANSI-accredited standards developers, which AMPP plans to continue. The merged standards program includes 25 standing standards committees that develop technical standards for industries including cathodic protection, coatings, defense, highways and bridges, rail, maritime, oil and gas, power and utilities, research and testing, tanks and pipelines, and water and wastewater.
Professional training and certifications
AMPP offers individual training and certification programs. Many are merged programs that originated as competing programs under the former NACE and SSPC organizations. Other programs are still being administered under the legacy NACE or SSPC frameworks until the merger is complete.
Contractor accreditation
AMPP administers accreditation programs for contractors working in the protective coatings and linings industries. "QP" stands for "Qualification Procedure", a reference to the technical standard that underlies each program.
QP 1, Field Application to Complex Industrial and Marine Structures
QP 2, Field Removal of Hazardous Coatings
QP 3, Shop Painting (QP 3 is a joint standard also used by AISC for their sophisticated paint endorsement.)
QP 5, Coating and Lining Inspection Companies
QP 6, Metallizing
QP 7, Painting Contractor Introductory Program
QP 8, Installation of Polymer Coatings and Surfacings on Concrete and Other Cementitious Surfaces
QP 9, Commercial Painting and Coating Contractors
QN 1, Nuclear Coating Supplement
QS 1, Advanced Quality Management System (ISO 9001-compliant)
References
External links
Professional associations based in the United States
Organizations established in 2021
Corrosion
Engineering societies | Association for Materials Protection and Performance | [
"Chemistry",
"Materials_science",
"Engineering"
] | 437 | [
"Engineering societies",
"Metallurgy",
"Corrosion",
"Electrochemistry",
"Materials degradation"
] |
68,602,630 | https://en.wikipedia.org/wiki/Fair%20division%20among%20groups | Fair division among groups (or families) is a class of fair division problems, in which the resources are allocated among groups of agents, rather than among individual agents. After the division, all members in each group consume the same share, but they may have different preferences; therefore, different members in the same group might disagree on whether the allocation is fair or not. Some examples of group fair division settings are:
Several siblings inherited some houses from their parents and have to divide them. Each sibling has a family, whose members may have different opinions regarding which house is better.
A partnership is dissolved, and its assets should be divided among the partners. The partners are firms; each firm has several stockholders, who might disagree regarding which asset is more important.
The university management wants to allocate some meeting-rooms among its departments. In each department there are several faculty members, with differing opinions about which rooms are better.
Two neighboring countries want to divide a disputed region among them. The citizens in each country differ on which parts of the region are more important. This is a common obstacle to resolving international disputes.
The "group of agents" may also represent different conflicting preferences of a single person. As observed in behavioral economics, people often change their preferences according to different frames of mind or different moods. Such people can be represented as a group of agents, each of whom has a different preference.
In all the above examples, the groups are fixed in advance. In some settings, the groups can be determined ad-hoc, that is, people can be grouped based on their preferences. An example of such a setting is:
Some 30 people want to use the local basketball court. Each game involves 10 players with different preferences regarding which time is better. It is required to partition the time of day into 3 parts and partition the players into 3 groups and assign a group to each time-slot.
Fairness criteria
Common fairness criteria, such as proportionality and envy-freeness, judge the division from the point-of-view of a single agent, with a single preference relation. There are several ways to extend these criteria to fair division among groups.
Unanimous fairness requires that the allocation be considered fair in the eyes of all agents in all groups. For example:
A division is called unanimously-proportional if every agent in every group values his/her group's share as at least 1/k of the total value, where k is the number of groups.
A division is called unanimously-envy-free if every agent in every group values his/her group's share at least as much as the share of any other group.
Unanimous fairness is a strong requirement, and often cannot be satisfied.
Aggregate fairness assigns to each group a certain aggregate function, such as: sum, product, arithmetic mean or geometric mean. It requires that the allocation be considered fair according to this aggregate function. For example:
A division is called average-proportional if, for each group, the arithmetic mean of the agents' values to the group share is at least 1/k of the total value.
A division is called product-envy-free if, for each group, the product of agents' values of the group share is at least the product of their values of the share of any other group.
Democratic fairness requires that, in each group, a certain fraction of the agents agree that the division is fair; preferredly this fraction should be at least 1/2. A practical situation in which such requirement may be useful is when two democratic countries agree to divide a certain disputed land among them, and the agreement should be approved by a referendum in both countries.
Unanimous-fairness implies both aggregate-fairness and democratic-fairness. Aggregate-fairness and democratic fairness are independent - none of them implies the other.
Pareto efficiency is another important criterion that is required in addition to fairness. It is defined in the usual way: no allocation is better for at least one individual agent and at least as good for all individual agents.
Results for divisible resources
In the context of fair cake-cutting, the following results are known (where k is the number of groups, and n is the number of agents in all groups together).
Unanimous fairness: Unanimous-proportional and unanimous-envy-free allocations always exist. However, they may be disconnected: at least n connected components might be required. With two groups, n components are always sufficient. With k>2 groups, O(n log k) components are always sufficient for a unanimous-proportional allocation, and O(n k) components are always sufficient for a unanimous-envy-free allocation. It is an open question whether or not n components are always sufficient.
Aggregate fairness: Average-proportional and average-envy-free allocations always exist, and require only k connected components (that is, each group may get a connected piece). However, they cannot be found using a finite algorithm in the Robertson–Webb query model.
Democratic fairness: 1/2-democratic proportional and 1/2-democratic envy-free allocations always exist. With two groups, there exist such allocations that are also connected, and they can be found in polynomial time. With k>2 groups, connected 1/2-democratic fair allocations might not exist, but the number of required components is smaller than for unanimous-proportional allocations.
Fairness and efficiency: All three variants of proportionality are compatible with Pareto-efficiency for any number of groups. Unanimous-envy-freeness is compatible with Pareto-efficiency for 2 groups, but not for 3 or more groups. 1/2-democratic envy-freeness is compatible with Pareto-efficiency for 2 groups, but not for 5 or more groups. It is open whether they are compatible for 3 or 4 groups.
The division problem is easier when the agents can be grouped ad-hoc based on their preferences. In this case, there exists a unanimous envy-free connected allocation for any number of groups and any number of agents in each group.
Unanimous proportionality and exact division
In an exact division (also called consensus division), there are n agents, and the goal is to partition the cake into k pieces such that all agents value all pieces at exactly 1/k. It is known that an exact division with n(k-1) always exists. However, even for k=2, finding an exact division with n cuts is FIXP-hard, and finding an approximate exact division with n cuts is PPA-complete (see exact division for more information). It can be proved that unanimous-proportionality is equivalent to consensus division in the following sense:
For every n and k, a solution to unanimous-proportional division among n(k-1)+1 agents grouped into k families implies a solution to consensus division among n agents with k pieces. In particular, it implies that unanimous-proportional division requires at least n-1 cuts (n components), finding a unanimous-proportional division with n-1 cuts is FIXP-hard, and finding an approximate unanimous-proportional division with n-1 cuts is PPA-hard.
For every n and k, a solution to exact-division among n agents and k pieces implies a solution to unanimous-proportional division among n+1 agents grouped into k families. In particular, it implies that exact unanimous-proportional division can be done with (n-1)(k-1) cuts, and that finding an approximate unanimous-proportional division is in PPA. The number of cuts is tight for k=2 families but not for k>2.
Results for indivisible items
In the context of fair item allocation, the following results are known.
Unanimous approximate maximin-share fairness:
When there are two groups, a positive multiplicative approximation to MMS-fairness can be guaranteed if-and-only-if the numbers of agents in the groups are (1,n-1) or (2,2) or (2,3). The positive results are attainable by polynomial-time algorithms. In all other cases, there are instances in which at least one agent with a positive MMS gets a zero value in all allocations.
When there are three or more groups, a positive multiplicative approximation to MMS-fairness can be attained if k-1 groups contain a single agent; in contrast, if all groups contain 2 agents and one group contains at least 5 agents, then no positive approximation is possible.
Unanimous approximate envy-freeness:
When there are two groups of agents with binary additive valuations, a unanimously-EF1 allocation exists if the group sizes are (1,5) or (2,3), but might not exist if the group sizes are (1,6) or (2,4) or (3,3). In general, an EFc allocation might not exist if the group sizes are . Note that, with binary valuations, EF1 is equivalent to EFX, but weaker than EFX0. A unanimously-EFX0 allocation might not exist if the group sizes are (1,2); this is in contrast to the situation with individual agents, that is, group sizes (1,1), where an EFX0 allocation always exists even for monotone valuations.
It is NP-hard to decide if a given instance admits a unanimously-EF1 allocation.
When there are two groups of agents with responsive valuations (a superset of additive valuations), a unanimously-EF1 balanced allocation exists if the group sizes are (1,2). If a certain conjecture on Kneser graphs is true, then a unanimously-EF1 balanced allocation exists also for group sizes (1,4), (2,3) and arbitrary monotone valuations. A unanimously-EFX allocation might not exist if the group sizes are (1,2).
For two ad-hoc groups, with any number of agents with arbitrary monotone valuations, there exists a unanimously-EF1 allocation. There also exists a balanced partition of the agents and a unanimously-EF1 balanced allocation of the goods. The EF1 cannot be strengthened to EFX even with additive valuations.
For k ad-hoc groups, with any number of agents with additive valuations, there exists a unanimously-PROP*1 allocation.
For n agents partitioned arbitrarily into k groups, there always exists an allocation that is envy-free up to c items, where . The same is true for proportionality up to c items. For consensus division the bounds are . All bounds are asymptotically tight when the number of groups is constant. The proofs use discrepancy theory.
Unanimous envy-freeness with high probability:
When all k groups contain the same number of agents, and their valuations are drawn at random, an envy-free allocation exists with high probability if the number of goods is in , and can be attained by a greedy algorithm that maximizes the sum of utilities.
The results can be extended to two groups with different sizes.
There is also a truthful mechanism that attains an approximately-envy-free allocation with high probability.
If the number of goods is in less than n, then with high probability, an envy-free allocation does not exist.
Democratic fairness:
For two groups with binary additive valuations (with any number of agents), there always exists a 1/2-democratic envy-free-except-1 allocation. The constant 1/2 is tight even if we allow envy-free-except-c allocation for any constant c. The same is true also for proportionality-except-c. A different fairness notion, that can be guaranteed to more than 1/2 of the agents in each group, is the ordinal maximin-share approximation. For every integer c, there exists a -democratic 1-out-of-c MMS-fair allocation. These allocations can be found efficiently using a variant of round-robin item allocation, with weighted approval voting inside each group. The upper bound on the fraction of agents that can be guaranteed 1 of their best c items (a property weaker than 1-out-of-c MMS) is . For , the lower bound for 1-out-of-best-c allocation can be improved from 1/2 to 3/5; it is an open question whether the upper bound of 3/4 can always be attained.
It is NP-hard to decide if a given instance admits an allocation that gives each agent a positive utility.
For two groups with general monotone valuations, there always exists a 1/2-democratic envy-free-except-1 allocation, and it can be found by an efficient algorithm.
For three or more groups with binary additive valuations, there always exists a 1/k-democratic envy-free-except-1 allocation; with general monotone valuations, there always exists a 1/k-democratic envy-free-except-2 allocation. The factor 1/k is tight for envy-free-except-c allocation for any constant c. If envy-freeness is relaxed to proportionality or maximin-share, then similar guarantees can be attained using a polynomial-time algorithm. For groups with additive valuations, a variant of round-robin item allocation can be used to find a 1/3-democratic 1-out-of-best-k allocation.
Group fair division of items and money
In the context of rental harmony (envy-free division of rooms and rent), the following results are known.
Unanimous envy-freeness (called strong envy-freeness in the paper) may not exist when the cost-sharing policy is equal or proportional, but always exists with free cost-sharing policy. Moreover, a unanimously-envy-free allocation with free cost-sharing that maximizes the total rent can be found in polynomial time.
With ad-hoc groups, unanimous envy-freeness exists even with equal cost-sharing policy.
Average envy-freeness (called aggregate envy-freeness in the paper) always exists when the cost-sharing policy is equal or proportional or free.
Fair division of ticket lotteries
A practical application of fair division among groups is dividing tickets to parks or other experiences with limited capacity. Often, tickets are divided at random. When people arrive on their own, a simple uniformly-random lottery among all candidates is a fair solution. But people often come in families or groups of friends, who want to enter together. This leads to various considerations in how exactly to design the lottery. The following results are known:
For the setting in which all group members are identified in advance, the Group Lottery mechanism orders groups uniformly at random, and processes them sequentially as long as there is available capacity. This natural mechanism might be unfair and inefficient; there are some better alternatives.
If agents may request multiple tickets without identifying members of their group, the Individual Lottery mechanism orders agents uniformly at random and awards each their request as long as there is available capacity. This common mechanism might yield arbitrarily unfair and inefficient outcomes. The Weighted Individual Lottery is an alternative mechanism in which the processing order is biased to favor agents with smaller requests. It is approximately fair and approximately efficient.
The Iterative Probability Maximization algorithm finds a lottery that maximizes the smallest utility (based on the egalitarian rule and the leximin order). It is group strategyproof, and attains a 1/2-factor approximation of the maximum utilization. It is also Pareto-efficient, envy-free and anonymous. Its properties are maximal in the sense that it is impossible to improve one property without harming another one.
Related concepts
Group envy-freeness is a fairness criterion for fair division among individual agents. It says that, after each individual agent gets his private share, no coalition of agents envies another coalition of the same size.
Club good is a resource that is consumed simultaneously by all members in a single group ("club"), but is excluded from members of other groups. In the group fair division problem, all allocated goods are club goods in the group they are allocated to.
Agreeable subset is a subset of items that is considered, by all people in a certain group, to be at least as good as its complement.
References
Fair division
Voting | Fair division among groups | [
"Mathematics"
] | 3,339 | [
"Recreational mathematics",
"Game theory",
"Fair division"
] |
68,603,783 | https://en.wikipedia.org/wiki/Red%20beryl | Red beryl, formerly known as bixbite and marketed as red emerald or scarlet emerald, is an extremely rare variety of beryl as well as one of the rarest minerals on Earth. The gem gets its red color from manganese ions embedded inside of beryllium aluminium cyclosilicate crystals. The color of red beryl is stable up to . Red beryl can come in various tints like strawberry, bright ruby, cherry, and orange.
The largest crystals of red beryl are about wide and long. However, most crystals are under long. Recently, the red variety of pezzottaite has been sold in markets as red beryl by some sellers.
History
Red beryl was discovered in 1904 by Maynard Bixby in the Wah Wah mountains in Utah. In 1912 the gem was named bixbite by Alfred Eppler after Maynard Bixby. The old synonym "bixbite" is deprecated, since it can cause confusion with the mineral bixbyite.
The greatest concentration of gem-grade red beryl comes from the Ruby-Violet Claim in the Wah Wah Mountains of mid-western Utah, discovered in 1958 by Lamar Hodges, of Fillmore, Utah, while he was prospecting for uranium. This claim was bought by Denise Knoeller as part of Red Emerald Inc. in 2020.
Rarity
Red beryl is very rare and has been reported only from a handful of locations: Wah Wah Mountains, Paramount Canyon, Round Mountain and Juab County, all in the south-western United States. The narrow geographic range suggests that the specific conditions needed for its formation do not occur frequently. This gem is a thousand times rarer than gold.
The Utah Geological Survey estimated that one red beryl is found for every 150,000 diamonds. According to Gemmological Association of Great Britain a 2 carat red beryl is as rare as a 40 carat diamond.
Red beryl is valued roughly the same price or higher than emerald despite being a hundred times rarer. Its rarity has made it less popular but red beryl crystals that are over 1 carat can sell for US$20,000. In 2008, one carat could sell for US$5000 or more.
Limited geographical occurrence means that the Red Emerald Inc controlled world production of natural red beryl as of 2021.
Characteristics
The dark red color of red beryl is attributed to ions. Red beryl rough crystals can be easily distinguished by hexagonal crystal systems. This gem has been known to be confused with pezzottaite, a caesium analog of beryl, that has been found in Madagascar and more recently Afghanistan; cut gems of the two varieties can be distinguished from their difference in refractive index. Red beryl is similar to emerald and dissimilar to other beryls in that it has inclusions like feathers and fractures. Some mineral inclusions include quartz, feldspar, hematite, and bixbyite.
Chemistry
The hexagonal crystal system found in beryls are formed of AlO6 octahedra, as well as BeO4 and SiO4 tetrahedra. The hexagonal chanels of red beryl are primarily unoccupied and no detectable water has been found within Red beryl gets its color from natural chemical doping, whereby Mn3+O6 replaces AlO6 at certain positions. The deep color Mn3+O6 may be in part explained by the Jahn-Teller effect on spin disallowed transitions.
Formation
While gem beryls are ordinarily found in pegmatites and certain metamorphic rock, red beryl forms in topaz-bearing rhyolites. It is formed by crystallizing under low pressure and high temperature from a pneumatolytic phase along fractures or within near-surface miarolitic cavities of the rhyolite. Associated minerals include bixbyite, quartz, orthoclase, topaz, spessartine, pseudobrookite and hematite. Synthetic red beryl is produced using hydrothermal process similar to that used for emeralds, however cobalt and manganese are used as dopants to produce a dark red gem.
References
Beryl group
Hexagonal minerals
Gemstones
Crystals | Red beryl | [
"Physics",
"Chemistry",
"Materials_science"
] | 879 | [
"Crystallography",
"Materials",
"Crystals",
"Gemstones",
"Matter"
] |
42,854,793 | https://en.wikipedia.org/wiki/Norsk%20Novaselskap | Norsk Novaselskap (the Norwegian Nova Society) was a Norwegian society organizing amateur astronomers in Norway. It was founded by Sigurd Einbu. Systematic observations and search for new variable stars was organised by the society. One of the most active members was Nobel laureate in chemistry, Odd Hassel, who for more than 50 years observed comets and variable stars.
References
Astronomy societies
Clubs and societies in Norway | Norsk Novaselskap | [
"Astronomy"
] | 84 | [
"Astronomy societies",
"Astronomy stubs",
"Astronomy organizations",
"Astronomy organization stubs"
] |
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